阅读说明：本技术 用于基于设备的动态延迟调整的系统 (System for device-based dynamic delay adjustment ) 是由 N.巴迪 C.福尔曼 J.鲁德 A.戈伊尔 于 2019-09-19 设计创作，主要内容包括：提供了用于基于设备的动态AV延迟调整的方法和设备。该方法包括被配置为位于靠近心房(A)位点和右心室(RV)位点的电极。该方法利用一个或多个处理器来检测心房起搏(Ap)事件或心房感测(As)事件,并测量与在Ap事件或As事件与感测心室(Vs)事件之间的间隔相对应的AV间隔。该AV间隔与当前心率(HR)相关联。该方法直接基于测量的AV间隔自动动态调整第一AV延迟,识别与当前HR相关联的比例因子,通过基于比例因子缩放第一AV延迟来计算第二AV延迟,并基于第一AV延迟和第二AV延迟来管理由IMD利用的起搏疗法。(Methods and devices are provided for device-based dynamic AV delay adjustment. The method includes an electrode configured to be positioned proximate to an atrial (a) site and a Right Ventricular (RV) site. The method utilizes one or more processors to detect atrial pacing (Ap) events or atrial sensing (As) events and measure AV intervals corresponding to intervals between the Ap events or As events and sensed ventricular (Vs) events. The AV interval is associated with the current Heart Rate (HR). The method automatically dynamically adjusts the first AV delay based directly on the measured AV interval, identifies a scaling factor associated with the current HR, calculates a second AV delay by scaling the first AV delay based on the scaling factor, and manages pacing therapies utilized by the IMD based on the first AV delay and the second AV delay.)

1. A method for device-based dynamic AV delay adjustment, the method comprising:

providing an electrode configured to be positioned proximate to an atrial (a) site and a Right Ventricular (RV) site;

utilizing one or more processors to:

detecting an atrial pacing (Ap) event or an atrial sensing (As) event;

measuring an AV interval corresponding to an interval between an Ap event or an As event and a sensed ventricular (Vs) event, the AV interval being associated with a current Heart Rate (HR);

automatically dynamically adjusting the first AV delay based directly on the measured AV interval;

identifying a scaling factor associated with the current HR;

calculating a second AV delay by scaling the first AV delay based on a scaling factor; and

managing pacing therapy utilized by the IMD based on the first AV delay and the second AV delay.

2. The method of claim 1, wherein the measured AV interval represents a measured As-Vs interval and the first AV delay represents sensed AV delays (AVDs) calculated by subtracting an offset from the measured As-Vs interval.

3. The method of claim 2, wherein the second AV delay represents a pacing AV delay (AVDp) calculated by multiplying or dividing AVDs by a scaling factor representing a ratio between a base As-Vs interval and a base Ap-Vs interval.

4. The method of claim 1, wherein the measured AV interval represents a measured Ap-Vs interval and the first AV delay represents a pacing AV delay (AVDp) calculated by subtracting an offset from the measured Ap-Vs interval.

5. The method of claim 4, wherein the second AV delay represents sensed AV delays (AVDs) calculated by multiplying or dividing AVDp by a scaling factor.

6. The method of claim 1, further comprising measuring a base As-Vs interval and a base Ap-Vs interval during a common base HR range; calculating a scale factor As a ratio between the base As-Vs interval and the Ap-Vs interval; and storing the scaling factors in association with the base HR range, wherein the identifying operation further comprises identifying the scaling factors based on a correlation between the current HR and the base HR range.

7. The method of claim 6, further comprising repeating the measuring, calculating and storing operations associated with different base HR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with different base HR ranges, wherein the identifying operation includes identifying a selected base HR range corresponding to the current HR from the base HR ranges and calculating the second AV delay using a scaling factor associated with the selected base HR range.

8. The method of claim 1, further comprising, during the search window, extending the first AV delay and the second AV delay to correspond to a default search AV delay (AVD)_search) (ii) a Sensing cardiac activity for a predetermined number of heart beats during a search window; identifying whether cardiac activity is indicative of a conduction block condition or a non-conduction block condition; and repeating the determining, calculating, and adjusting operations only when a non-conduction block condition is identified.

9. The method of claim 8, wherein the identifying operation comprises delaying AVD while searching for AV delay by default_searchWhen less than a selected number of heart beats exhibit sensed ventricular events, cardiac activity is identified as indicative of a conduction block condition.

10. The method of claim 1, wherein the scaling factor is between a base As-Vs interval and a base Ap-Vs interval.

11. An Implantable Medical Device (IMD) comprising:

an electrode configured to be positioned proximate to an atrial (a) site and a Right Ventricular (RV) site;

a memory storing program instructions;

one or more processors configured to implement program instructions to:

detecting an atrial pacing (Ap) event or an atrial sensing (As) event;

measuring an AV interval corresponding to an interval between an Ap event or an As event and a sensed ventricular (Vs) event, the AV interval being associated with a current Heart Rate (HR);

automatically dynamically adjusting the first AV delay based directly on the measured AV interval;

identifying a scaling factor associated with the current HR between the base AS-Vs interval and the base Ap-Vs interval;

calculating a second AV delay by scaling the first AV delay based on a scaling factor; and

managing pacing therapy utilized by the IMD based on the first AV delay and the second AV delay.

12. The IMD of claim 11, wherein the measured AV interval represents a measured As-Vs interval, and the first AV delay represents sensed AV delays (AVDs) calculated by subtracting an offset from the measured As-Vs interval.

13. The IMD of claim 12, wherein the second AV delay represents a pacing AV delay (AVDp) calculated by multiplying or dividing AVDs by a scaling factor.

14. The IMD of claim 11, wherein the measured AV interval represents a measured Ap-Vs interval, the first AV delay represents a pacing AV delay (AVDp) calculated by subtracting an offset from the measured Ap-Vs interval.

15. The IMD of claim 14, wherein the second AV delay represents sensed AV delays (AVDs) calculated by multiplying or dividing AVDp by a scaling factor.

16. The IMD of claim 11, wherein the one or more processors are further configured to measure a basal As-Vs interval and a basal Ap-Vs interval during a common basal HR range; and storing the scaling factors in association with the base HR range, wherein the identifying operation further comprises identifying the scaling factors based on the current HR and the base HR range.

17. The IMD of claim 16, wherein the one or more processors are further configured to repeat the measuring and storing operations associated with different base HR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with different base HR ranges, wherein the identifying operation includes identifying a selected base HR range from the base HR ranges that corresponds to the current HR, and calculating a second AV delay using a scaling factor associated with the selected base HR range.

18. The IMD of claim 11, wherein the one or more processors are further configured to, during a search window, extend the first AV delay and the second AV delay to correspond to a default search AV delay (AVD)_search) (ii) a Sensing cardiac activity for a predetermined number of heart beats during a search window; identifying whether cardiac activity is indicative of a conduction block condition or a non-conduction block condition; and repeating the determining, calculating, and adjusting operations only when a non-conduction block condition is identified.

19. A method for device-based dynamic a-HIS delay adjustment, the method comprising:

providing an electrode configured to be positioned proximate to an atrial (a) site and a HIS bundle (HIS) site;

utilizing one or more processors to:

detecting an atrial pacing (Ap) event or an atrial sensing (As) event;

measuring an A-HIS interval corresponding to an interval between an Ap event or an As event and a sensed HIS bundle event, the AV interval being associated with a current Heart Rate (HR);

automatically dynamically adjusting the first A-HIS delay based directly on the measured A-HIS interval;

identifying a scaling factor associated with the current HR;

calculating a second A-HIS delay by scaling the first A-HIS delay based on a scaling factor; and

managing pacing therapy utilized by the IMD based on the first A-HIS delay and the second A-HIS delay.

20. The method of claim 19, wherein the measured a-HIS interval represents a measured As-HIS interval and the first a-HIS delay represents a sensed a-HIS delay calculated by subtracting an offset from the measured As-HIS interval, wherein the second a-HIS delay represents a paced a-HIS delay calculated by multiplying or dividing a sensed a-HIS delay by a scaling factor representing a ratio between a base As-HIS interval and a base Ap-HIS interval.

Technical Field

Embodiments herein relate generally to implantable medical devices and, more particularly, to adjusting atrioventricular delays associated with intrinsic and paced atrial activity.

Background

Advances in Implantable Medical Device (IMD) and Left Ventricular (LV) lead designs have improved electrical stimulation, delay, and pacing, leading to better patient outcomes. Loss of Atrioventricular (AV) electrical and mechanical synchrony can lead to insufficient ventricular depolarization leading to suboptimal therapy. Optimal AV delay (AVD) can improve electrical synchrony by fusing intrinsic conduction wavefronts with device pacing to produce enhanced ventricular depolarization and increased cardiac output.

Cardiac Resynchronization Therapy (CRT) has been shown to improve the hemodynamics of Heart Failure (HF) patients, particularly when the AVD has been individualized for each patient. When an AVD is selected for each patient based on Echocardiogram (ECG) or blood pressure metrics, AVD programming for each patient is typically done clinically at the time of implantation. This disposable, static AVD option does not account for short-term changes (hourly; e.g., movement, sleep) or long-term changes (monthly; e.g., disease progression) in the patient's electromechanical conduction after the patient leaves the clinic.

At least one scheme for adjusting AVD over time has been proposed. In this conventional scheme, the AV interval (AVI) is measured and the AVD is set equal to the AV interval by a fixed amount programmed by the clinician. Periodically, conventional schemes extend the AVD to re-measure the intrinsic AV interval. This scheme programs two different AV delays in parallel: avd (avds) after sensing atrial events and avd (avdp) after pacing atrial events.

However, conventional schemes experience certain limitations in relation to the two use cases related to AVDs and AVDp. The first example occurs when intrinsic AV intervals are measured during atrial sensing (e.g., As-Vs events: intrinsic atrial beats [ As ] sensed by the RA lead and then intrinsic ventricular beats [ Vs ] sensed by the RV lead). The As related intrinsic AV interval is used to calculate a new value of AVDs for delivering ventricular pacing (Vp) after each subsequent As event. However, the new AVDp value is also programmed to handle any potential atrial pacing event. In the current scenario, AVDp is set equal to AVDs plus a fixed time period set by the clinician. In other words, conventional approaches indirectly calculate a new AVDp by extending the AVDs by the difference between the clinically programmed longer default pacing and sensing AVD values.

The second use case occurs when the intrinsic AV interval (e.g., Ap-Vs event: delivery of a paced atrial beat Ap by the RA lead, and then sensing of intrinsic ventricular beat Vs by the RV lead) is measured during atrial pacing. The Ap-related intrinsic AV interval is used to calculate a new AVDp value that is used to deliver Vp after each subsequent Ap event. Similar to the scenario described above, the new values of AVDs are also programmed to handle any potential atrial sensed event. In the current protocol, AVDs is set equal to AVDp minus a fixed time period set by the clinician.

Typically, clinicians set AVDp-default to be greater than AVDs-default to account for differences between the following intervals: (i) the conduction time (Ap-Vs) from the atrial pacing beat to the ventricular lead, and (ii) the time (As-Vs) from the sinus node proper beating sensed by the atrial lead to the same beating sensed by the ventricular lead. However, the difference between the programmed default AVDs-default and AVDp-default values is typically not based on patient-specific conductance measurements. The nature of the original atrial event (i.e., As or Ap) is important when attempting to provide synchronized therapy. When the conventional approach reprograms both AVDs and AVDp, the device may switch from atrial sensing to atrial pacing (or vice versa) during an extended series of beats (e.g., 32 beats or 256 beats). During the extended beat series in which the device delivers atrial pacing, the device also uses the indirectly calculated AVDp value to determine when to deliver ventricular pacing. AVDp is not directly calculated from the measured Ap-Vs interval, and thus there is a possibility that the device may not time ventricular pacing events in the desired manner. Given that the AVDp is not patient-specific, an indirectly calculated AVDp may not provide adequate AV synchronization. Similarly, conventional solutions program AVDs directly when they measure the Ap-Vs interval associated with atrial pacing events. There is a possibility that the device may not time ventricular pacing events in the desired manner. Given that the AVDs are not patient specific, indirectly calculated AVDs may not provide adequate AV synchronization.

There remains a need for methods and systems that provide dynamic AV timing adjustments that adapt to each patient's continuously changing cardiovascular state.

Disclosure of Invention

According to embodiments herein, a method for device-based dynamic AV delay adjustment is provided. The method includes an electrode configured to be positioned proximate to an atrial (a) site and a Right Ventricular (RV) site. The method utilizes one or more processors for detecting atrial pacing (Ap) events or atrial sensed (As) events and measures AV intervals corresponding to intervals between the Ap events or As events and sensed ventricular (Vs) events. The AV interval is associated with the current Heart Rate (HR). The method automatically dynamically adjusts the first AV delay based directly on the measured AV interval, identifies a scaling factor associated with the current HR, calculates a second AV delay by scaling the first AV delay based on the scaling factor, and manages pacing therapies utilized by the IMD based on the first AV delay and the second AV delay.

Alternatively, the measured AV interval may represent a measured As-Vs interval, and the first AV delay may represent sensed AV delays (AVDs) that may be calculated by subtracting an offset from the measured As-Vs interval. The second AV delay may represent a pacing AV delay (AVDp) that may be calculated by multiplying or dividing AVDs by a scaling factor. The scaling factor may represent a ratio between the base As-Vs interval and the base Ap-Vs interval.

The measured AV interval may represent a measured Ap-Vs interval and the first AV delay may represent a pacing AV delay (AVDp) that may be calculated by subtracting an offset from the measured Ap-Vs interval. The second AV delay may represent sensed AV delays (AVDs) that may be calculated by multiplying or dividing AVDp by a scaling factor.

Optionally, the method may further include measuring the base As-Vs interval and the base Ap-Vs interval during a common base HR range. The method may calculate a scaling factor As a ratio between the underlying As-Vs interval and the Ap-Vs interval, and may store the scaling factor in association with the underlying HR range. The identifying operation may further include identifying a scaling factor based on a correlation between the current HR and the base HR range. The method may further include repeating the measuring, calculating, and storing operations associated with the different base HR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with the different base HR ranges. The identifying operation may include identifying a selected base HR range from the base HR ranges that may correspond to the current HR, and may calculate the second AV delay using a scaling factor associated with the selected base HR range.

Optionally, during the search window, the method may extend the first AV delay and the second AV delay to correspond to a default search AV delay (AVD)_search). The method may sense cardiac activity for a predetermined number of heart beats during a search window, may identify cardiac activityWhether a motion indicates a conduction block condition or a non-conduction block condition, and the determining, calculating, and adjusting operations may be repeated only when a non-conduction block condition is identified. The identifying operation may include delaying AVD while searching for AV delay by default_searchWhen less than a selected number of heart beats exhibit sensed ventricular events, cardiac activity is identified as indicative of a conduction block condition. The scaling factor may be between the base As-Vs interval and the base Ap-Vs interval.

According to embodiments herein, Implantable Medical Devices (IMDs) are provided. The device includes an electrode configured to be positioned proximate an atrial (a) site and a Right Ventricular (RV) site. The memory stores program instructions. The one or more processors are configured to implement program instructions to detect atrial pacing (Ap) events or atrial sensing (As) events and measure AV intervals corresponding to intervals between the Ap events or As events and sensed ventricular (Vs) events. The AV interval is associated with the current Heart Rate (HR). The method automatically dynamically adjusts the first AV delay based directly on the measured AV interval and identifies a scaling factor associated with the current HR between the base As-Vs interval and the base Ap-Vs interval. The method calculates a second AV delay by scaling the first AV delay based on a scaling factor and manages pacing therapies utilized by the IMD based on the first AV delay and the second AV delay.

Alternatively, the measured AV interval may represent a measured As-Vs interval, and the first AV delay may represent sensed AV delays (AVDs) that may be calculated by subtracting an offset from the measured As-Vs interval. The second AV delay may represent a pacing AV delay (AVDp), which may be calculated by multiplying or dividing AVDs by a scaling factor. The measured AV interval may represent a measured Ap-Vs interval and the first AV delay may represent a pacing AV delay (AVDp), which may be calculated by subtracting an offset from the measured Ap-Vs interval. The second AV delay may represent sensed AV delays (AVDs), which may be calculated by multiplying or dividing AVDp by a scaling factor.

Optionally, the one or more processors may be further configured to measure a base As-Vs interval and a base Ap-Vs interval during the common base HR range. The device may store a scaling factor associated with the base HR range. The identifying operation may further include identifying a scaling factor based on the current HR and the base HR range. The one or more processors may be further configured to repeat the measurements and may store operations associated with different base HR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with the different base HR ranges. The identifying operation may include identifying a selected base HR range from the base HR ranges that may correspond to the current HR, and may calculate the second AV delay using a scaling factor associated with the selected base HR range.

Optionally, during the search window, the one or more processors may extend the first AV delay and the second AV delay to correspond to a default search AV delay (AVD)_search). The processor may sense cardiac activity for a predetermined number of heart beats during the search window, may identify whether the cardiac activity is indicative of a conduction block condition or a non-conduction block condition, and may repeat the determining, calculating, and adjusting operations only when the non-conduction block condition is identified.

According to embodiments herein, a method for device-based dynamic a-HIS delay adjustment is provided. The method provides an electrode configured to be positioned proximate to an atrial (a) site and a HIS bundle (HIS) site. The method utilizes detecting atrial pacing (Ap) events or atrial sensing (As) events with one or more processors and measuring a-HIS intervals corresponding to intervals between the Ap events or As events and sensed HIS bundle events. The AV interval is associated with the current Heart Rate (HR). The method automatically dynamically adjusts the first A-HIS delay based directly on the measured A-HIS interval and identifies a scaling factor associated with the current HR. The method calculates a second a-HIS delay by scaling the first a-HIS delay based on a scaling factor and manages pacing therapies utilized by the IMD based on the first and second a-HIS delays.

Alternatively, the measured A-HIS interval may represent a measured As-HIS interval, and the first A-HIS delay may represent a sensed A-HIS delay, which may be calculated by subtracting an offset from the measured As-HIS interval. The second a-HIS delay may represent a pacing a-HIS delay, which may be calculated by multiplying or dividing the sensing a-HIS delay by a scaling factor. The scaling factor may represent a ratio between the base As-HIS interval and the base Ap-HIS interval.

Drawings

Fig. 1 illustrates an Implantable Medical Device (IMD) intended for subcutaneous implantation at a site near the heart according to embodiments herein.

Fig. 2 shows a schematic diagram of an IMD according to embodiments herein.

Fig. 3A illustrates a computer-implemented method for measuring and binning (bin) AV intervals and calculating scale factors according to embodiments herein.

FIG. 3B illustrates a computer-implemented method for setting AVDs and AVDp values directly or by scaling according to embodiments herein.

Fig. 4 illustrates an overall process for implementing AV synchronization according to embodiments herein.

Detailed Description

The term "As-Vs spacing" As used herein refers to the measured intrinsic conduction time from sensing an atrial (As) event to sensing a ventricular (Vs) event. The sensed ventricular event may be a right ventricular event or a left ventricular event. The term "Ap-Vs interval" as used herein refers to the measured intrinsic conduction time from pacing an atrial (Ap) event to sensing a ventricular (Vs) event. The sensed ventricular event may be a right ventricular event or a left ventricular event.

The term "As-RVs interval" As used herein refers to the measured intrinsic conduction time from sensing atrial (As) events to sensing Right Ventricular (RVs) events. The term "Ap-RVs interval" as used herein refers to the measured intrinsic conduction time from pacing atrial (Ap) events to sensing Right Ventricular (RVs) events.

The term "As-LVs spacing" As used herein refers to the measured intrinsic conduction time from sensing atrial (As) events to sensing Left Ventricular (LVs) events. The term "Ap-LVs interval" as used herein refers to the measured intrinsic conduction time from pacing an atrial (Ap) event to sensing a Left Ventricular (LVs) event.

The terms "atrioventricular delay" and "AVD" refer to a programmed time delay to be used by an implantable medical device in connection with delivering therapy.

The term "AVDs" refers to AVDs associated with delivering therapy at a ventricular site subsequent to sensing an atrial event when an intrinsic ventricular event does not occur prior to the expiration of the AVDs.

The term "AVDp" refers to AVDs associated with delivering therapy at a ventricular site following a paced atrial event when an intrinsic ventricular event does not occur prior to AVDp expiration.

The term "a-LVDp" refers to the AVD associated with delivering therapy at the left ventricular site following a paced atrial event when an intrinsic left ventricular event does not occur prior to the expiration of a-LVDp.

The term "A-LVDs" is used to refer to AVDs associated with the delivery of therapy at the left ventricular site following intrinsic sensing of atrial events when intrinsic left ventricular events do not occur prior to the expiration of A-LVDs.

The term "LV-only pacing" refers to the mode of operation of an implanted medical device in which the LV paces but the RV does not pace.

According to embodiments herein, methods and systems are described for dynamic adjustment of AVD while accounting for dependent changes in the nature of atrial events between atrial pacing events and atrial sensing events. The dynamic adjustment of AVDs and AVDp of the embodiments herein while accounting for differences between the As-Vs and Ap-Vs spacing is in a patient-specific manner. The As-Vs and Ap-Vs intervals are measured directly at similar heart rates, and the pace/sense (P/S) scaling factor is calculated As the ratio between the basal AV intervals derived from the measurement of sensed and paced atrial events (R ═ basal Ap-Vs/basal As-Vs). During operation, when the As-Vs spacing is measured in the search window and used to define AVDs, a corresponding scaled AVDp value is calculated based on the AVDs and the scale factor, such As AVDp ═ AVDs × R. Alternatively, when the AP-Vs interval is measured during the search window and used to define AVDp, a corresponding scaled AVDs value is calculated based on AVDp and the scaling factor, such as AVDs ═ AVDp/R. Using the scaling factor to convert between AVDp and AVDs values, embodiments herein account for patient-specific differences in As-Vs and Ap-Vs spacing that depend on the relative positions of the atrial lead, the sinoatrial node, and the atrioventricular node, and the corresponding conduction velocities. In addition, using a scaling factor to convert between AVDp and AVDs values, embodiments herein demarcate any dependence of the As-Vs and Ap-Vs intervals on Heart Rate (HR).

Embodiments herein may be implemented in conjunction with IMDs that provide right-side pacing (e.g., RA and RV leads) and/or IMDs that provide biventricular pacing (e.g., RA, RV, and LV leads such as quadrupolar LV leads).

Fig. 1 illustrates an Implantable Medical Device (IMD)100 according to embodiments herein, intended for subcutaneous implantation at a site near a heart 111. The IMD 100 may be a dual chamber stimulation device capable of treating both fast and slow arrhythmias with stimulation therapies including cardioversion, pacing stimulation, implantable cardioverter-defibrillator, suspended tachycardia detection, tachyarrhythmia therapy, and the like. The IMD 100 may include a housing 101 for housing electronic/computing components. The housing 101 (which is commonly referred to as a "can," "housing," "package," or "housing electrode") may be programmably selectable as a return electrode for certain stimulation modes. The housing 101 also includes a connector 109 having a plurality of terminals 200 and 210 (as shown in fig. 2).

IMD 100 is shown electrically connected to heart 111 by way of a Left Atrial (LA) lead 120, Left Atrial (LA) lead 120 having a right lead 112 and a Left Atrial (LA) ring electrode 128. IMD 100 is also electrically coupled to heart 111 by way of a Right Ventricular (RV) lead 110, which in this embodiment, Right Ventricular (RV) lead 110 has a Left Ventricular (LV) electrode 132 (e.g., P4), an LV electrode 134 (e.g., M3), an LV electrode 136 (e.g., M2), and an LV electrode 138 (e.g., D1). RV lead 110 is inserted intravenously into heart 111 to place RV coil 122 at the RV apex, and SVC coil electrode 116. RV lead 110 is therefore capable of receiving cardiac signals and delivering stimulation to right ventricle 140 (also referred to as the RV chamber) in the form of pacing and shock therapy. IMD 100 includes RV tip electrode 126, as well as Right Atrial (RA) electrode 123. RV lead 110 includes RV tip electrode 126, RV ring electrode 124, RV coil electrode 122, and SVC coil electrode 116.

IMD 100 includes left ventricular 142 (e.g., left chamber) pacing therapy and is coupled to a multipolar LV lead 114, which multipolar LV lead 114 is designed for placement in various locations, such as the "CS region" (e.g., the venous vasculature of the left ventricle, including the Coronary Sinus (CS), the great cardiac vein, the left peripheral vein, the posterior left ventricular vein, the central vein, and/or any portion of the cautious vein or any other cardiac vein accessible to the coronary sinus), the epicardial space, and so forth.

In an embodiment, the LV lead 114 is designed to receive atrial and ventricular cardiac signals and deliver left ventricular pacing therapy using a set of multiple LV electrodes 132, 134, 136, 138. LV lead 114 may also deliver left atrial pacing therapy using at least LA ring electrode 128 and deliver percussive therapy using at least LA ring electrode 128. In an alternative embodiment, LV lead 114 includes LV electrodes 138, 136, 134, and 132, but does not include LA electrode 130. The LV lead 114 may be, for example, a Quartet developed by St.Jude Medical Inc. (headquarters in St. Paul, Minn.)^TMAn LV pacing lead comprising four pacing electrodes on the LV lead. Although three leads 110, 112, and 114 are shown in fig. 1, fewer or additional leads with various configurations of pacing, sensing, and/or shocking electrodes may alternatively be used. For example, LV lead 114 may have more or fewer than the four LV electrodes 132-138.

Referring to the distance of LV electrode 132 (also referred to as P4) from right ventricle 140, this electrode is shown as the most "distal" LV electrode. LV electrode 138 (also referred to as D1) is shown as LV electrode 132-138 "proximal" most to left ventricle 142. LV electrodes 136 and 134 are shown as "intermediate" LV electrodes (also referred to as M3 and M2) between distal LV electrode 138 and proximal LV electrode 132, respectively. Thus, to more closely describe their relative positions, LV electrodes 138, 136, 134 and 132 may be referred to as electrodes D1, M2, M3 and P4, respectively (where "D" represents "distal", "M" represents "intermediate", "P" represents "proximal", and s is arranged from most distal to most proximal as shown in FIG. 1). Optionally, more or fewer LV electrodes than the four LV electrodes D1, M2, M3, and P4 may be provided on lead 114.

LV electrodes 132-138 are configured such that each electrode may be utilized to deliver pacing pulses and/or sense pacing pulses (e.g., monitor the response of LV tissue to pacing pulses). In either the pacing vector or the sensing vector, each LV electrode 132-138 may be controlled to act as a cathode (negative electrode). Pacing pulses may be provided directionally between the electrodes to define a pacing vector. In a pacing vector, the generated pulse is applied to the surrounding myocardial tissue through the cathode. The electrodes defining the pacing vector may be electrodes in the heart 111 or located outside the heart 111 (e.g., on the housing/casing device 101). For example, housing/casing 101 may be referred to as housing 101 and serves as an anode in a unipolar pacing and/or sensing vector. RV coil 122 may also act as an anode in unipolar pacing and/or sensing vectors. LV electrodes 132-138 may be used to provide a variety of different vectors. Some of the vectors are intraventricular LV vectors (e.g., the vector between two of LV electrodes 132-138), while other vectors are interventricular vectors (e.g., the vector between LV electrode 132-138 and RV coil 122 or another electrode away from left ventricle 142). Various exemplary bipolar sensing vectors with LV cathodes may be used for sensing using LV electrodes D1, M2, M3, and P4 and RV coil 122. Various other types of leads and IMD 100 may be used with various other types of electrodes and electrode combinations. The use of an RV coil electrode as the anode is only one example. Various other electrodes may be configured as the anode electrode.

Additionally or alternatively, leads may be implanted with electrodes located near one or more HIS bundles. Optionally, one or more of the leads shown in fig. 1 may be provided with one or more additional electrodes located near the HIS bundle. Electrodes located proximate to the HIS beam may be configured to sense electrical activation at the HIS beam and/or deliver pacing pulses to the HIS beam.

Fig. 2 shows a schematic diagram of an IMD of 100. The IMD 100 may be a dual chamber stimulation device capable of treating both fast and slow arrhythmias with stimulation therapies including cardioversion, pacing stimulation, implantable cardioverter-defibrillator, suspended tachycardia detection, tachyarrhythmia therapy, and the like.

The IMD 100 has a housing 101 for housing electronic/computing components. The housing 101 (which is commonly referred to as a "can," "housing," "package," or "housing electrode" to my new) may be programmably selectable as a return electrode for certain stimulation modes. The housing 101 also includes a connector (not shown) having a plurality of terminals 200 and 210. These terminals may be connected to electrodes located at various locations within or around the heart. For example, the terminal may include: a terminal 200 to be coupled to a first electrode (e.g., a tip electrode) located in the first chamber; a terminal 202 to be coupled to a second electrode located in the second chamber; a terminal 204 to be coupled to an electrode located in the first chamber; a terminal 206 to be coupled to an electrode located in the second chamber; a terminal 208 to be coupled to the electrode; and a terminal 210 to be coupled to an electrode located in the strike circuit 280. The type and location of each electrode may be different. For example, the electrodes may include various combinations of rings, tips, coils, and strike electrodes, among others.

The IMD 100 includes a programmable microcontroller 220, the programmable microcontroller 220 controlling various operations of the IMD 100, including cardiac monitoring and stimulation therapies. Microcontroller 220 includes a microprocessor (or equivalent control circuitry), one or more processors, RAM and/or ROM memory, logic and timing circuits, state machine circuitry, and I/O circuitry. The IMD 100 also includes an atrial and/or ventricular pulse generator 222, which atrial and/or ventricular pulse generator 222 generates stimulation pulses for connecting desired electrodes to appropriate I/O circuitry to facilitate electrode programmability. The switch 226 is controlled by a control signal 228 from the microcontroller 220.

The pulse generator 222 is shown in fig. 2. Optionally, IMD 100 may include a plurality of pulse generators similar to pulse generator 222, wherein each pulse generator is coupled to one or more electrodes and controlled by microcontroller 220 to deliver selected stimulation pulse(s) to the corresponding one or more electrodes. The IMD 100 includes sensing circuitry 244 selectively coupled to one or more electrodes, the sensing circuitry 244 performing sensing operations through the switch 226 to detect the presence of cardiac activity in a chamber of the heart 111. The output of the sensing circuit 244 is connected to the microcontroller 220, which microcontroller 220 in turn triggers or deactivates the pulse generator 222 in response to the absence or presence of cardiac activity. Sensing circuit 244 receives control signals 246 from microcontroller 220 for the purpose of controlling the timing of gain, threshold, polarization charge removal circuits (not shown), and any blocking circuits (not shown) coupled to the inputs of the sensing circuit.

In the example of fig. 2, a sensing circuit 244 is shown. Optionally, IMD 100 may include a plurality of sensing circuits 244 similar to sensing circuits 244, wherein each sensing circuit is coupled to one or more electrodes and controlled by microcontroller 220 to sense electrical activity detected at the corresponding one or more electrodes. The sensing circuit 224 may operate in a unipolar sensing configuration or a bipolar sensing configuration.

The IMD 100 also includes a analog-to-digital (A/D) Data Acquisition System (DAS)250 coupled to one or more electrodes via switches 226 to sample cardiac signals across any desired electrode pairs. The DAS 250 is configured to acquire intracardiac electrogram signals, convert the raw analog data to digital data, and store the digital data for later processing and/or telemetry transmission to an external device 254 (e.g., a programmer, local transceiver, or diagnostic system analyzer). The DAS 250 is controlled by control signals 256 from the microcontroller 220.

Microcontroller 220 includes arrhythmia detector 234 for analyzing cardiac activity signals sensed by sensing circuitry 244 and/or DAS 250. Arrhythmia detector 234 is configured to analyze cardiac signals sensed at various sensing sites.

The microcontroller 220 also includes an AVD adjustment module 235 configured to, among other things, perform the operations of the methods described herein. The AVD adjustment module 235 is configured to implement program instructions to: detecting an atrial pacing (Ap) event or an atrial sensing (As) event; measuring an AV interval corresponding to an interval between an Ap event or an As event and a sensed ventricular (Vs) event, the AV interval being associated with a current Heart Rate (HR); automatically dynamically adjusting the first AV delay based directly on the measured AV interval; identifying a scaling factor between a base As-Vs interval and a base Ap-Vs interval associated with a current HR; calculating a second AV delay by scaling the first AV delay based on the scaling factor; and managing pacing therapy utilized by the IMD based on the first AV delay and the second AV delay. The AVD adjustment module 235 determines the base As-Vs and base Ap-Vs spacing during the calibration mode. After calibration, the AVD adjustment module 235 enters a search mode to detect changes in the AV interval.

When the AVD adaptation module 235 measures the AV interval resulting from sensing atrial events, the AVD adaptation module 235 specifies a first AV delay to represent sensed AV delays (AVDs), and directly calculates the AVDs by subtracting an offset from the measured As-Vs interval. The offset may be a preprogrammed value entered by a physician and/or automatically recognized by the IMD. Alternatively, the offset may represent a percentage-based offset calculated according to one or more embodiments described in the related co-pending applications identified and incorporated herein by reference. AVD adjustment module 235 indirectly sets a second AV delay, representing a pacing AV delay (AVDp). The AVD adjustment module 235 calculates the scaled AVDp by multiplying or dividing the AVDs by a scaling factor determined from the base interval.

Alternatively, during the search mode, AVD adjustment module 235 specifies a first AV delay to represent a pacing AV delay (AVDp) when the measured AV interval results from a pacing atrial event. AVDp is calculated by subtracting an offset from the measured Ap-Vs interval. The AVD adjustment module 235 defines a second AV delay to represent sensed AV delays (AVDs). Scaled AVDs are calculated by multiplying or dividing AVDp by a scaling factor.

During the calibration mode, one or more scaling factors are derived that relate to one or more HR ranges. For each HR range, the AVD adjustment module 235 may be further configured to measure a base As-Vs interval and a base Ap-Vs interval during the heartbeat within the common base HR range. The AVD adjustment module 235 stores a scaling factor associated with each base HR range. Thereafter, during an operation of dynamically adjusting the AV delay (e.g., fig. 3B), the AVD adjustment module 235 identifies one of the scaling factors to use based on the current HR identified during the search mode. The AVD adjustment module 235 may also be configured to repeat the measurements and store operations associated with different base HR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with the different base HR ranges. When multiple scaling factors for different HR ranges are determined, during the operation of fig. 3B, the AVD adjustment module 235 identifies a selected base HR range from the multiple base HR ranges that corresponds to the current HR and calculates a second AV delay using the scaling factor associated with the selected base HR range.

Additionally or alternatively, during the search window, the AVD adjustment module 235 may be further configured to extend the first AV delay and the second AV delay to correspond to a default search AV delay (AVD)_search). The AVD adjustment module 235 senses cardiac activity for a predetermined number of heart beats during the search window, identifies whether the cardiac activity is indicative of a conduction block condition or a non-conduction block condition, and repeats the determining, calculating, and adjusting operations only when the non-conduction block condition is identified.

Additionally or alternatively, AVD is delayed when searching for AV delay in default_searchDuring which beats less than the selected number of heart beats exhibit sensed ventricular events, AVD adjustment module 235 identifies cardiac activity as indicative of a conduction block condition.

Additionally or alternatively, AVD adjustment module 235 may specify the first AV delay and the second AV delay to correspond to sensed AV delays (AVDs) and paced AV delays (AVDp). The AVD adjustment module 235 may also be configured to identify the presence of conduction block and, in response thereto, restore the AVDs and AVDp to the base AVDs-base and AVDp-base programmed lengths, respectively; and maintaining the base AVDp-base and base AVDs-base programmed lengths for a selected second number of heart beats.

Additionally or alternatively, the AVD adjustment module 235 may be configured to perform the operations discussed above and the operations described below in connection with sensing intrinsic activity at HIS beam sites (HIS ss) and delivering pacing pulses at the HIS beam sites. For example, a HIS beam sensing/pacing site may replace one or more right ventricular sensing/pacing sites. As another example, the HIS beam sensing/pacing site may replace one or more left ventricular sensing/pacing sites. When the HIS beam sensing/pacing site is replaced with a left or right ventricular sensing/pacing site, the operations described herein are pre-performed between sensing or pacing atrial events and sensing HIS beam events instead of sensing ventricular events.

The microcontroller 220 is operatively coupled to the memory 260 by a suitable data/address bus 262. The programmable operating parameters used by the microcontroller 220 are stored in the memory 260 and used to customize the operation of the IMD 100 to suit the needs of a particular patient. Operating parameters of IMD 100 may be non-invasively programmed into memory 260 via telemetry communication by telemetry circuitry 264 with external device 254 via communication link 266 (e.g., MICS, low energy bluetooth, etc.).

The IMD 100 may also include one or more physiological sensors 270. Such sensors are commonly referred to as "rate responsive" sensors because they are typically used to adjust the pacing stimulation rate according to the patient's motion state. However, the physiological sensor 270 may also be used to detect changes in cardiac output, changes in physiological conditions of the heart, or diurnal changes in activity (e.g., to detect sleep and wake states). The signal generated by the physiological sensor 270 is passed to the microcontroller 220 for analysis. Although shown as being included within the IMD 100, the physiological sensor(s) 270 may be external to the IMD 100, yet still be implantable in or carried by the patient. Examples of physiological sensors may include, for example, sensors that sense respiration rate, pH of blood, ventricular gradients, activity, position/posture, Minute Ventilation (MV)/and so forth.

Battery 272 provides operating power to all components in IMD 100. Battery 272 can operate at low current drain (current drains) for long periods of time and can provide high current pulses (for capacitive charging) when the patient requires a shock pulse (e.g., a period of time exceeding 2A, voltage above 2V for 10 seconds or more). The battery 272 also desirably has predictable discharge characteristics so that selective replacement times can be detected. As one example, IMD 100 employs a lithium/silver vanadium oxide battery.

The IMD 100 also includes an impedance measurement circuit 274 that may be used for a number of things, including sensing respiratory phase. An impedance measurement circuit 274 is coupled to the switch 226 so that any desired electrodes and/or terminals can be used to measure the impedance associated with monitoring the respiratory phase.

The microcontroller 220 also controls the shock circuit 280 by way of a control signal 282. The shock circuit 280 generates shock pulses of low energy (e.g., up to 0.5 joules), medium energy (e.g., 0.5-10 joules), or high energy (e.g., 11-40 joules) as controlled by the microcontroller 220. Such shock pulses are applied to the heart of the patient via the shock electrodes. It may be noted that the shock therapy circuit is optional and may not be implemented in the IMD 100.

Microcontroller 220 also includes timing control 232 for controlling the timing of such stimulation pulses (e.g., pacing rate, atrial-ventricular (AV) delay, atrial-to-atrial (a-a) delay, or ventricular-to-ventricular (V-V) delay), as well as maintaining timing tracking refractory periods, blanking intervals, noise detection windows, evoked response windows, alert intervals, marker channel timing, and the like. Switch 226 includes a plurality of switches for connecting the desired electrodes to the appropriate I/O circuitry, thereby providing full electrode programmability. Thus, as known in the art. The switch 226 determines the polarity (e.g., unipolar, bipolar, etc.) of the stimulation pulses by selectively closing appropriate switch combinations (not shown) in response to a control signal 228 from the microcontroller 220.

Microcontroller 220 is shown to include timing control 232 to control the timing of the stimulation pulses (e.g., pacing rate, Atrioventricular (AV) delay, atrial-to-atrial (a-a) delay, or ventricular-to-ventricular (V-V) delay, etc.). The AV delay is managed to provide a fused AV delay to fuse the timing of the pacing pulse with the intrinsic wavefront. The timing control 232 may also be used for timing of refractory periods, blanking intervals, noise detection windows, evoked response windows, alert intervals, marker channel timing, and the like. The microcontroller 220 also has a morphology detector 236 to review and analyze one or more characteristics of the morphology of the cardiac signal. Although not shown, the microcontroller 220 may also include other specialized circuitry and/or firmware/software components that assist in monitoring various conditions of the patient's heart and managing pacing therapies.

The IMD 100 is also equipped with a communication modem (modulator/demodulator) 240 to enable wireless communication with other devices, implanted devices, and/or external devices. In one embodiment, the communication modem 240 may use high frequency modulation of the signal transmitted between the electrode pairs. As one example, signals may be transmitted in the high frequency range of about 10-80kHz, as such signals pass through body tissues and fluids without stimulating the heart or being felt by the patient.

Fig. 3A illustrates a computer-implemented method for measuring and binning AV (and/or a-HIS) intervals and calculating scale factors according to embodiments herein. The method is under the control of one or more processors configured with certain executable instructions. The method may be partially or completely implemented by one or more processors of the IMD. Additionally or alternatively, the method may be implemented partially or completely by one or more processors of a local external device (e.g., a smartphone, a bedside monitor, a clinician programmer) and/or a remote server. As explained later, the operations of fig. 3A may be performed during calibration and/or during a search mode associated with AV sync setting operations. Alternatively, the operations of fig. 3A may be performed after termination of the search mode after the patient is experiencing identification of a normal conduction or abnormal conduction block condition. Alternatively, the operations of FIG. 3A may be performed when the heart rate changes and moves from one HR range to another HR range. The operations of FIG. 3A are primarily described in connection with atrial and ventricular events, but it will be understood that operations related to atrial and HIS bundle events may be performed instead of or in addition to those related to atrial and ventricular events.

At 302, one or more processors detect a pacing atrial (Ap) event or a sensing atrial (As) event. One or more AV interval timers are started when a pacing or sensing atrial event is detected.

At 304, the one or more processors monitor the RV sense channel for a sensed ventricular (Vs) event. Vs events may occur at the RV sensing site or the LV sensing site, or both. Alternatively, sensing rv (rvs) events may be detected separately from sensing lv (lvs) events.

At 304, the one or more processors automatically decrease the currently programmed pacing rate, such as by setting the base pacing rate 5-10bpm lower than the pacing rate that would otherwise be set based on the current intrinsic heart rate. The process of fig. 3A allows intrinsic atrial events to occur by reducing the programmed pacing rate. The basal pacing rate is only reduced by a few beats per minute (bpm), so if intrinsic atrial events do not occur, the IMD will eventually deliver therapy even during extended pacing rates. In addition, the one or more processors also set the sensed AV delay to a duration greater than a time interval that would otherwise be set based on intrinsic sensing of atrial and sensed ventricular events. By extending the sensed AV delay, the process of fig. 3A allows intrinsic ventricular events to occur. The sensed AV delay is extended only by a predetermined amount, and thus, if an intrinsic ventricular event does not occur, the IMD will eventually deliver ventricular therapy even during the extended sensed AV delay.

At 306, the one or more processors determine a measured AV interval. The measured AV interval may correspond to the interval between sensing atrial events and sensing ventricular events (As-Vs interval) or the interval between pacing atrial events and sensing ventricular events (Ap-Vs interval). The processor records the measured AV interval As an As-Vs interval or an Ap-Vs interval, respectively, based on whether the atrial event at 302 is a sensed event or a paced event.

Optionally, according to embodiments herein, measurements may be performed between right atrial events and right ventricular events and between right atrial events and left ventricular events in conjunction with multi-point pacing (MPP), through right ventricular and left ventricular leads. When performing left ventricular sensing and pacing according to embodiments herein, the abbreviations and nomenclature herein may refer to Right Ventricular (RV) events and Left Ventricular (LV) events, respectively. For example, embodiments utilizing MPP may measure the interval between sensing atrial events and sensing left ventricular events (As-LVs interval) and/or the interval between pacing atrial events and sensing left ventricular events (Ap-LVs interval).

It is recognized that in some cases, sensing a ventricular event may not occur. When no sensed ventricular event has occurred, flow returns along 303 and the processor waits for a new pace or detection of a sensed atrial event before resetting the timer.

Alternatively, the operation at 302 and 306 associated with obtaining the As-Vs spacing may be performed a plurality of times (e.g., three to five times), and the As-Vs spacing may then be averaged or otherwise mathematically combined to obtain an average or other mathematical combination representing the As-Vs spacing. Similarly, the operation at 302 and 306 associated with obtaining the Ap-Vs interval may be performed multiple times, which is then averaged or otherwise mathematically combined to obtain an average or other mathematical combination representing the Ap-Vs interval. The Ap-Vs interval is automatically measured by increasing the base pacing rate by a predetermined amount (e.g., 5-10bpm) greater than the pacing rate otherwise indicated by the intrinsic heart rate. By increasing the basal pacing rate, the process forcibly paces the delivery of atrial events. In addition, the one or more processors also set the sensed AV delay to a duration greater than a time interval that would otherwise be set based on intrinsic sensing of atrial and sensed ventricular events. By extending the sensed AV delay, the process of fig. 3A allows intrinsic ventricular events to occur.

At 308, the one or more processors identify a current heart rate associated with the As-Vs interval or the Ap-Vs interval. For example, heart rate may be defined in terms of the interval between atrial and ventricular events. Additionally or alternatively, the interval between atrial and ventricular events may be used to calculate a beat per minute heart rate. Additionally or alternatively, the processor may track the beats per minute heart rate separated from the interval measured at 306.

The AES-Vs interval and the Ap-Vs interval measured are heart rate dependent, as a faster heart rate results in a faster conduction velocity during normal AV conduction. Thus, operations at 306 and 308 measure the AES-Vs interval and the Ap-Vs interval during similar heart rates or within a predetermined heart rate range.

At 310, the one or more processors record an As-Vs interval or an Ap-Vs interval, such As in a heart rate bin (bin) corresponding to the heart rate identified at 308. For example, a series of heart rate (FIR) bins may be maintained for different heart rate ranges (e.g., 30-50bpm, 50-65bpm, 65-80bpm, 80-95bpm, etc.). The durations may be the same for different heart rate ranges, or different from each other. For example, the duration of a single heart rate range may vary based on a determination of which conduction times of the As-Vs interval and the Ap-Vs interval are more accurately correlated at different heart rates. As another example, it may be determined that the As-Vs interval and the Ap-Vs interval in the HR range of 60-70bpm should be binned together, but separated from the As-Vs interval and the Ap-Vs interval with heart rates below 60bpm or above 70 bpm. As another example, the As-Vs intervals and the Ap-Vs intervals in the HR range 70-95 may be binned together without significant change to the scaling operations described herein.

At 312, the one or more processors determine whether to repeat the process for additional heart beats. If so, flow returns to 302. Otherwise, the process ends. The process of fig. 3A is repeated until the processor determines that a sufficient number of AV intervals have been measured that are associated with pacing atrial events and sensing atrial events and that are associated with the HR range of interest. For example, it may be desirable to obtain an AV interval of 5 or 10 As and Ap events. Additionally or alternatively, the decision at 312 may be based in part on whether a sufficient number of AV intervals are measured for each HR bin. For example, it may be desirable to measure 2-5 As-Vs intervals and 2-5 Ap-Vs intervals while the heart rate is in each of a selected number of heart rate ranges (e.g., below 60bpm, 60-90bpm, 90-120bpm, above 120 bpm). Once the desired number of AV intervals are measured for each type of atrial event and for each HR range of interest, the process moves to 314.

At 314, the one or more processors calculate a scaling factor between a base AES-Vs interval and a base Ap-Vs interval associated with the current heart rate. The base AES-Vs interval and the base Ap-Vs interval may be obtained during a single iteration by the operations at 302-310. Alternatively, the base AES-Vs interval and the base Ap-Vs interval may be obtained based on an average or other mathematical combination of measurements obtained during multiple iterations through the operations at 302 and 310. The processor stores the scale factors associated with the base HR range and, as explained herein, the stored scale factors are utilized during subsequent adjustments of the AV delay when a subsequent (current) HR is within the base HR range.

To validate the procedure herein, cardiac activity data was analyzed from a QRS assessment study of 100 patients into which a Cardiac Resynchronization Therapy (CRT) device had been implanted. The QRS assessment study included approximately 30 minutes of cardiac activity data collected from each patient. During the 30 minute period for each patient, the patient's heart rate was varied between different HR ranges. With data collection over a 30 minute period, 49 of the patients exhibited Ap-Vs events and As-Vs events at heart rates within a common heart rate bin. For example, 49 patients each exhibited at least one Ap-Vs event and at least one As-Vs event in a common heart rate compartment (e.g., 60-70bpm, 70-80bpm, etc.). The Ap-Vs interval and the As-Vs interval measured at heart rates within the common HR bin are analyzed to calculate an (average) basal Ap-Vs interval and an (average) basal As-Vs interval, respectively. For each heart rate range, a scaling factor is then calculated from the ratio of the basal As-Vs interval and the basal Ap-Vs interval (e.g., R ═ average Ap-Vs)/(average As-Vs)). A scaling factor is calculated for each heart rate bin for which cardiac activity data is collected. For 49 patients in the QRS assessment study, the overall mean scale factor (R) was 1.27+/-0.31, with a range of 0.29 to 1.89. When outliers were removed and scale factors in the range of 5-95 percentiles were retained, the average ratio for the remaining 44 patients was R1.31 +/-0.21, with a range of 0.68 to 1.83. From the foregoing data, it appears clear that for a single patient, a consistent scaling factor can be derived with little variation with respect to As-Vs and Ap-Vs intervals, which are recorded in relation to heart rate within a common heart rate bin.

The process of obtaining the scale factor of fig. 3A may be performed a single time during one calibration operation for each patient. In addition, more complex implementations may involve frequent calibration, where the operations of fig. 3A are repeated based on various criteria. As explained herein, the second AV delay is calculated using one or more scaling factors by scaling the first AV delay based directly on the measured AV interval.

In accordance with the operation of FIG. 3A, the basal As-Vs interval and the basal Ap-Vs interval are measured during different heart beats occurring while the heart rate is within a common basal FIR range. The processor repeats the measuring and storing operations associated with the different base FIR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with the different base FIR ranges. Thereafter, the processor identifies a selected base FIR range from the plurality of base FIR ranges that corresponds to the current FIR. The processor calculates a second AV delay using the scaling factor associated with the selected base FIR range.

The operations of fig. 3A may be performed during a clinical visit, such as with an external programmer device. Additionally or alternatively, the operations of fig. 3A may be performed by the IMD during a clinical visit or at home.

Alternatively, the operations of fig. 3A may be performed between the atrial site and the HIS bundle site. For example, operations at 304 may monitor the HIS beam channels for sensing HIS beam events. Operations at 306 may determine a measured atrial-to-HIS bundle interval, while operations at 310 record either As-HIS intervals or Ap-HIS intervals in the corresponding heart rate bins. Operations at 314 may calculate and save a corresponding scaling factor between the base As-HISs interval and the base Ap-HISs interval associated with the current heart rate.

Alternatively, the operations of fig. 3A may be performed between an atrial site, one or more ventricular sites, and a HIS bundle site.

FIG. 3B illustrates a computer-implemented method for setting AVDs and AVDp values directly or by scaling according to embodiments herein. The method is under the control of one or more processors configured with certain executable instructions. The method may be partially or completely implemented by one or more processors of the IMD. Additionally or alternatively, the method may be implemented partially or completely by one or more processors of a local external device (e.g., a smartphone, a bedside monitor, a clinician programmer) and/or a remote server. As explained later, the operation of fig. 3B may be performed by the IMD during a search mode related to the AV sync setting operation. Alternatively, the operations of fig. 3B may be performed after termination of the search mode after the patient is experiencing identification of a normal conduction or abnormal conduction block condition. Alternatively, the operations of FIG. 3B may be performed when the heart rate changes and moves from one HR range to another HR range. The operations of FIG. 3B are primarily described in connection with atrial and ventricular events, but it will be understood that operations related to atrial and HIS bundle events may be performed instead of or in addition to those related to atrial and ventricular events.

At 350, the one or more processors measure the As-Vs spacing or the Ap-Vs spacing. For example, the processor may perform operations similar to those at 302-306 to detect an As or Ap event, start a timer and measure the time from the As or Ap event to a Vs event.

At 352, the one or more processors identify one or more offsets to be used to set the AVDs and AVDp. The offset may be programmed by a clinician and/or automatically derived by the IMD based on recorded physiological characteristics. Alternatively, the offset may be set equal to a percentage (e.g., 20%) of the measured AV interval, such as Percentage (PB) -based offset (AV interval) × P1%, where P1% corresponds to a percentage programmed by the clinician and/or automatically derived by the IMD based on the recorded physiological characteristics. The offset may be determined based on the procedures described in the above-mentioned related co-pending applications.

At 354, the one or more processors automatically dynamically adjust the first AV delay based directly on the measured AV interval. For example, when the measured AV interval represents the measured As-Vs interval, the first AV delay represents sensed AV delays (AVDs) calculated by subtracting an offset from the measured As-Vs interval. Alternatively, when the measured AV interval represents the measured Ap-Vs interval, the first AV delay represents a pacing AV delay (AVDp) calculated by subtracting an offset from the measured Ap-Vs interval.

At 356, the one or more processors identify a current heart rate associated with the measured As-Vs interval or the Ap-Vs interval.

At 358, the one or more processors identify a scale factor associated with the current heart rate. As explained herein, the scaling factor identifies the relationship between the underlying As-Vs interval and the underlying Ap-Vs interval for a common heart rate or heart rate range/bin. For example, the processor uses the current heart rate to identify the corresponding FIR bins. The processor obtains a scaling factor associated with an HR bin that includes the current HR. As another example, it may be assumed that the process of FIG. 3A generates scale factors of 1.2, 1.3, and 1.4 associated with HR bins of 40-60bpm, 60-70bpm, and 70-90bpm, respectively. The processor obtains a scale factor of 1.3 when the current HR is between 60 and 70 bpm.

At 360, the one or more processors calculate a second AV delay by scaling the first AV delay based on the scaling factor. For example, when the second AV delay represents a pacing AV delay (AVDp), AVDp may be calculated by multiplying or dividing AVDs by a scaling factor. Alternatively, when the second AV delay represents sensed AV delays (AVDs), the AVDs may be calculated by multiplying or dividing AVDp by a scaling factor.

The determination of whether to multiply or divide AVDp by the scale factor depends in part on the contents of the numerator and denominator that make up the scale factor. For example, when the scale factor R is defined by the As-Vs interval divided by the Ap-Vs interval, AVDp scales by AVDs R or AVDs scales by AVDp/R. When the scaling factor R is (Ap-Vs interval)/(As-Vs interval), the AVDs are scaled by AVDp R, or AVDp is scaled by AVDs/R.

At 362, the one or more processors manage the pacing therapy utilized by the IMD based on the first AV delay and the second AV delay.

Using the scaling factor to convert between AVDp and AVDs values, embodiments herein account for patient-specific differences in As-Vs and Ap-Vs spacing that depend on the relative positions of the atrial lead, the sinoatrial node, and the atrioventricular node, and the corresponding conduction velocities. The automatic calculation of the scale factors from direct measurements of the As-Vs interval and the Ap-Vs interval, rather than generalizing the differences in sensed and paced atrial delays, ensures that the transition to/from sensed AV delay and paced AV delay is individualized for each patient. The scaling factor utilizes the ratio between the As-Vs interval and the Ap-Vs interval, in part to cancel the dependency on heart rate. To the extent that heart rate is a function of both intervals, the effect of heart rate is negated by using the As-Vs and Ap-Vs intervals in a common heart rate bin.

As described herein, the scaling factor may be obtained during a single calibration operation for each patient. Alternatively, measurement of the As-Vs and Ap-Vs intervals may be performed by the IMD periodically (e.g., daily) and/or based on other criteria (e.g., exhibiting certain physiological behaviors). By performing calibration periodically, embodiments herein update the scaling factor and account for any potential heart rate dependencies.

In the foregoing embodiment, a separate scaling factor is stored in association with each heart rate range. Additionally or alternatively, the scaling factors for all heart rates and/or a subset of the heart rate ranges may be combined, such as by averaging or some other mathematical operation.

Thereafter, embodiments of an AV synchronization process for utilizing scaling factors and pacing/sensing AV delays as described herein are described. Additionally or alternatively, the scaling factors and pacing/sensing AV delays calculated herein may be utilized in conjunction with other therapy management procedures, such as in conjunction with any IMD features that adjust AV delays and need to account for translation between atrial pacing and atrial sensing.

Alternatively, the operations of fig. 3B may be performed between the atrial site and the HIS bundle site. For example, operations at 350 may determine a measured atrial (paced or sensed) to HIS beam interval, while operations at 350 identify an offset based thereon. The operation at 354 may dynamically adjust the first a-HIS delay directly from the offset. Operations at 358 may identify an HIS scale factor for the current heart rate, and operations at 360 calculate a second a-HIS delay by scaling the first a-HIS delay based on the scale factor. Alternatively, the operations of fig. 3B may be performed between an atrial site, one or more ventricular sites, and a HIS bundle site.

Fig. 4 illustrates an overall process for implementing AV synchronization according to embodiments herein. The AV synchronization process utilizes the device-based dynamic AV delay adjustment process of fig. 3A and 3B.

At 402, when an AV synchronization process is activated, one or more processors enter a search mode for a search window of a predetermined duration. During the search mode, the processor sets the AVDp and AVDs values equal to the corresponding AV search delay (collectively referred to as AVD)_search). The AV search delay is set long enough to wait for an intrinsic RV event that may be delayed after pacing an atrial or sensing an atrial event. However, AV search delay AVD_searchNot too long to avoidPacing is delayed when the patient should be paced in other ways. For example, AVD_searchMay be set to be between 300 and 400ms, and more preferably, AVDp may be set to be equal to 300ms to 350ms, and AVDs may be set to be equal to 325ms to 375 ms. Additionally or alternatively, the first AVD_searchCan be set in relation to measuring As-Vs interval (e.g., 325ms), while the second AVD is set_searchMay be set in relation to the measurement Ap-Vs interval (e.g., 350 ms). The processor may remain in the search mode for a search window corresponding to a predetermined number of beats (e.g., 5 beats, 10 beats) and/or a predetermined period of time (e.g., 10 seconds). Additionally or alternatively, the processor may remain in the search mode until a condition is satisfied, such as a particular physiological mode being detected (e.g., 3 consecutive Vs events being detected). While in the search mode, the processor tracks cardiac activity.

When the search mode is terminated, the one or more processors determine whether the tracked cardiac activity indicates a conduction block or whether a sufficient number of Vs events are detected. For example, all or a selected number of beats are exhibited in the AVD during the search mode_searchUpon a Vs event detected before the expiration of time, the processor may declare the series of beats to exhibit a normal or non-stuck condition, in response to which flow moves to 404. As another example, during a series of 4-8 beats, during AVD_searchBefore the expiration of time, 3 or more consecutive beats may exhibit a sensed ventricular Vs event, in which case the processor declares the series of events as normal.

When the flow proceeds to 404, the one or more processors measure one or more AV intervals and set an AVD based on the measured AV intervals, as described herein (e.g., in connection with the operations of fig. 3A and 3B). For example, As explained in connection with FIG. 3B, the measured AV interval represents the As-Vs interval when associated with intrinsic atrial events. The measured As-Vs interval is used to directly dynamically adjust the AVDs (representing the first AV delay) when the intrinsic atrial event occurs. The AVDs are then multiplied by a scaling factor (corresponding to the current heart rate) to calculate a second AV delay corresponding to AVDp as a scaled version of the AVDs. Alternatively, when a paced atrial event occurs, the measured Ap-Vs interval is used to dynamically adjust the AVDp directly (representing the first AV delay) at 404. The AVDp is then multiplied by the scaling factor to calculate a second AV delay corresponding to the AVDs as a scaled version of the AVDp.

The processor may use the selected end or the middle of the jump measured during the search window As the measured As-Vs or Ap-Vs interval. For example, at the start of search mode (and setting the AV delay to AVD)_searchTime), the processor may use the third or fourth event/beat As the measured As-Vs or Ap-Vs interval to allow the AV interval to be at AVD_searchThe time changes then stabilize.

Alternatively, when two types of atrial events occur during the search window (e.g., one or more beats with intrinsic atrial events and one or more beats with paced atrial events), the processor may select one type of atrial event and utilize the measured AV intervals associated with the selected type of atrial event while ignoring any measured AV intervals associated with non-selected types of atrial events. For example, when at least one event of a selected type occurs during the search window (e.g., sensing an atrial event), the processor may default to using the measured AV interval of the selected type (at 404 and 416). Alternatively, the processor may utilize a particular heart beat (e.g., 3 rd heart beat) from the search window. Alternatively, the processor may utilize measured AV intervals for types of atrial events that occur more frequently during the search window. For example, the As-Vs interval may be measured when 2-3 beats have intrinsic atrial events and only 1-2 beats have paced atrial events.

Alternatively, for a desired number of beats, the As-Vs spacing or the Ap-Vs spacing may be calculated As an average (or other mathematical combination) of a number of As-Vs spacing and Ap-Vs spacing, respectively. For example, when most of the heart beats during the search window include intrinsic atrial events, an average As-Vs interval may be calculated from all or a selected number of the measured As-Vs intervals. Similarly, when a majority of the heart beats during the search window include a pacing atrial event, an average Ap-Vs interval may be calculated from all or a selected number of the measured Ap-Vs intervals. Alternatively, the AVDs and AVDp may be set at 404 in various ways based on the nature of the events that occur during the search mode. For example, as described above in connection with FIG. 3B, both AVDs and AVDp values may be set (at 402) in response to a selected number (e.g., 3-5) of consecutive Vs events occurring during the search mode.

Additionally or alternatively, the AVDs and AVDp delays may be set in alternative manners in response to other combinations of atrial and ventricular events occurring during the seek mode. It may be desirable to utilize selected combinations of atrial and ventricular events as criteria for setting AVDs and AVDp delays, such as to skip single or paired ectopic ventricular premature beats (PVCs). For example, the one or more processors may search for a particular type of atrial event during a selected beat within a search window. For example, the one or more processors may determine the type of atrial event occurring during the third, fourth, or fifth beats during the seek mode and, based thereon, set the AVDs and AVDp delays in a desired manner. As a more specific example, when the processor determines that an atrial As event occurred during the third beat but before the third sensed ventricular event, the processor may set the AV delay As follows: AVDs ═ As-Vs spacing) - (offset) and AVDp ═ AVDs R, where R is the scaling factor between the measured basal Ap-Vs spacing and the measured basal As-Vs spacing (e.g., R ═ average basal Ap-Vs spacing)/(average basal As-Vs spacing)). In the foregoing example, AVDs are directly set based on the As-Vs spacing, while AVDp is offset based on AVDs and the scale factor and PBs. Alternatively, when the processor determines that a paced atrial Ap event occurs before a third sensed ventricular event, the processor may set the AV delay as follows: AVDp ═ AVDp interval) - (offset) and AVDs ═ AVDp/R. By setting the AVDs and AVDp based on the type of atrial event occurring during the third or later beat, the processor skips a single or paired ectopic PVC beat.

The AVDp and AVDs values set at 404 are maintained for a selected first number of heart beats (e.g., 20-40 beats) associated with a normal or non-conduction block condition.

Go back to402, when less than a selected number of beats exhibit a Vs event during the search window, the processor may declare that the series of beats exhibit an abnormal or conduction block condition. When an abnormal or conduction block condition is identified, flow moves to 406. For example, three consecutive Vs events may not occur during the search mode. Alternatively, during a series of 4-8 beats, during AVD_searchLess than 3 consecutive beats may exhibit a Vs event before the time expires.

At 406, the processor identifies the presence of conduction block (or similar abnormal condition) and, in response thereto, restores the AVDs and AVDp delays to the base programmed length (e.g., set AVDp-base equal to 100ms to 150ms and AVDs-base equal to 125ms to 175 ms). The length of the base AVDp-base and AVDs-base is maintained for a selected extended second number of heartbeats (e.g., 200-.

The AVDp and AVDs values set at 404 or 406 are used by the IMD for a corresponding number of heartbeats (e.g., 20-40 or 200- "300), after which the process continues to 410. At 410, the one or more processors reset the AVDp and AVDs values to the AV search delay AVD after a corresponding number of selected heart beats_searchThereby entering the search mode again. The AV search delay set at 410 may be the same as or different from the AV search delay set at 402. The duration of the search pattern at 410 may be the same as or different from the duration of the search pattern at 402. For example, the processor may maintain the search pattern for 5 or more beats at 410, where AVDp is 350ms and AVDs is 325 ms. At 410, the one or more processors determine whether a selected number of consecutive sensed ventricular Vs events have occurred, and based thereon, flow branches along 412 or 414. For example, flow branches along 414 when three or another number of consecutive Vs events are detected during the search window.

At 414, the one or more processors measure one or more AV intervals and set AVDp and AVDs based on the measured AV intervals and PB offset. As explained above in connection with 404, at 416, one of the As-Vs spacing and the Ap-Vs spacing is measured and used to directly adjust the corresponding one of the AVDs and AVDp values. The other of AVD S and VDP is then indirectly computed as a scaled version of the former. More specifically, when the measured AV interval represents the As-Vs interval, the measured As-Vs interval is used to dynamically adjust the AVDs (representing the first AV delay) directly. Then, the AVDs are multiplied by the scaling factor to calculate a second AV delay corresponding to the AVDp as a scaled version of the AVDs. Alternatively, when a paced atrial event occurs, the measured Ap-Vs interval is used to dynamically adjust the AVDp directly (representing the first AV delay) at 410. The AVDp is then multiplied by the scaling factor to calculate a second AV delay corresponding to the AVDs as a scaled version of the AVDp. Thereafter, the AVDp and AVDs values set at 416 are maintained for a selected number of heart beats (e.g., 200 beats and 300 beats).

Returning to 410, when the one or more processors determine that fewer than a selected number of consecutive sensed ventricular Vs events have occurred, the processors determine that the patient exhibits a conduction block condition, and in response thereto, flow branches 412 and returns to 406. For example, when the processor does not detect three or another selected number of consecutive sensed ventricular Vs events during the search mode, the processor may identify a conduction block condition and flow branches along 412. As described above, at 406, the AVDp and AVDs values are restored to the base program length for a longer selected number of beats, such as 300x2N beats, before reentering the seek mode. The variable N is equal to the number of consecutive searches in which the conduction block is identified.

Additionally or alternatively, any time a selected number of consecutive sensed ventricular Vs events occur (e.g., within a 30 or 300 beat window) while the AVDp and AVDs values have decreased, as described above, both the AVDp and AVDs values are further decreased, such as another 30 beats, before reentering the seek mode. Additionally or alternatively, whenever the processor determines that it may be desirable to further reduce the AVDp and AVDs values, after having been reduced, the processor may first enter a search mode for a shortened search window (e.g., after 30 beats rather than 300 beats) to allow the processor to perform a fast AV interval assessment.

The foregoing process of dynamically adjusting pacing and sensing AV delay of fig. 3B is described in connection with one example of an overall synchronization process (fig. 4). Alternatively, the dynamic process of fig. 3B may be implemented in conjunction with other static or dynamic methods for programming pacing and sensing AV delay.

The foregoing operations are described in connection with pacing and sensing events in the right atrium and right ventricle. Additionally or alternatively, embodiments herein may be implemented in connection with pacing and sensing events in the left ventricle. For example, the one or more processors monitor and detect right sensing ventricular RVs events and monitor and detect left sensing ventricular LVs events. RVs events occur at RV sensing sites, and LVs events occur at LV sensing sites. When the LV lead includes multiple electrodes, such as in combination with multi-point pacing (MPP), different ones of the LV electrodes may be designated to serve as LV sensing sites. For example, one of the distal or intermediate LV sensing sites may be utilized to monitor and detect left sensed ventricular events.

The operations of fig. 3B may be repeated or supplemented, where measuring the a-LV interval may correspond to the interval between sensing an atrial event and sensing a left ventricular event (As-LVs interval) and/or the interval between pacing an atrial event and sensing a left ventricular event (Ap-LVs interval). The one or more processors calculate a scaling factor (R) As a ratio of the measured underlying As-LVs interval(s) and the underlying Ap-LVs interval(s) [ R ═ As-LVs interval)/(Ap-LVs interval ]. Additionally or alternatively, the scaling factor may be calculated As a percentage P1% [ R ═ As-LVs interval)/(Ap-LVs interval) × P1% ] of the ratio of the measured base As-LVs interval and the base Ap-LVs interval, where P1% corresponds to the percentage programmed by the clinician and/or automatically derived by the IMD based on the recorded physiological characteristic.

When implemented in conjunction with multi-point pacing, the operations of fig. 3B may be repeated in conjunction with the left ventricular pacing and sensing site. For example, the one or more processors automatically and dynamically directly adjust at least the first A-LV delay and indirectly calculate the second A-LV delay by scaling the first A-LV delay. For example, at 350, when one or more processors measure As-LVs spacing, the processor sets sensed atrial events directly to sensed left ventricular events to a-LVDs ═ As-LVs spacing) - (offset). The processor indirectly sets a delay associated with pacing the atrial event until sensing the left ventricular event to a-LVDp — a-LVDs R based on the scaling factor. Similarly, when one or more processors measure Ap-LVs interval, the processor sets pacing atrial events to sensing left ventricular events directly to a-LVDp ═ Ap-LVs interval) - (offset). The processor indirectly sets a delay associated with sensing atrial events to a-LVDs-a-LVDp R until sensing left ventricular events based on the scaling factor.

Alternatively, the proposed independent a-RV and a-LV delays may be extended for use with multiple LV pace/sense sites. With biventricular MPP, AVDs and AVDp values for three or more pacing sites (RV, LV1, LV2, etc.) can be dynamically programmed: A-RVDs and A-RVDp, A-LVDs1 and A-LVDp1, and A-LVDs2 and A-LVDp 2. Alternatively, with LV-only MPP, only two AVD values will be dynamically programmed: A-LVDs1 and A-LVDp1, and A-LVDs2 and A-LVDp2, such as for the intermediate and distal electrodes.

Final phrase

The various methods as illustrated in the figures and described herein represent exemplary embodiments of methods. These methods may be implemented in software, hardware, or a combination thereof. In various approaches, the order of the steps may be changed, and various elements may be added, reordered, combined, omitted, modified, etc. Various steps may be performed automatically (e.g., without direct prompting by user input) and/or programmatically (e.g., according to program instructions).

Various modifications and changes may be made as will be apparent to those skilled in the art having the benefit of this disclosure. It is intended to embrace all such modifications and changes and, accordingly, the above description to be regarded in an illustrative rather than a restrictive sense.

Various embodiments of the present disclosure utilize at least one network familiar to those skilled in the art to support communications using any of a variety of commercial protocols, such as transmission control protocol/internet protocol ("TCP/IP"), user datagram protocol ("UDP"), protocols operating in layers of the open systems interconnection ("OSI") model, file transfer protocol ("FTP"), universal plug and play ("UpnP"), network file system ("NFS"), universal internet file system ("CIFS"), and AppleTalk. For example, the network may be a local area network, a wide area network, a virtual private network, the Internet, an intranet, an extranet, a public switched telephone network, an infrared network, a wireless network, a satellite network, and any combination thereof.

In embodiments utilizing a web server, the web server may run any of a variety of servers or mid-tier applications, including a hypertext transfer protocol ("HTTP") server, an FTP server, a common gateway interface ("CGI") server, a data server, a Java server, an Apache server, and a business application server. The server(s) may also be capable of executing programs or scripts in response to requests from user devices, such as by executing one or more network applications, which may be implemented in any programming language (such asC. C #, or C + +, or any scripting language (such as Ruby, PHP, Perl, Python, or TCL), and combinations thereof. The server(s) may also include database servers, including but not limited toAndand open source servers such as MySQL, Postgres, SQLite, MongoDB, and any other server capable of storing, retrieving, and accessing structured or unstructured data. The database servers may include table-based servers, document-based servers, unstructured servers, relational servers, non-relational servers, or a combination of these and/or other database servers.

As mentioned above, the environment may include various data stores and other memory and storage media. These may reside in various locations, such as on any or all storage media local to (and/or resident in) one or more of the computers or remote to the computer across a network. In a particular set of embodiments, the information may reside in a storage area network ("SAN") familiar to those skilled in the art. Similarly, any necessary files to perform the functions attributed to a computer, server, or other network device may be stored locally and/or remotely as appropriate. Where the system includes computerized devices, each such device may include hardware elements that may be electrically connected via a bus, including, for example, at least one central processing unit ("CPU" or "processor"), at least one input device (e.g., a mouse, keyboard, controller, touch screen, or keyboard), and at least one output device (e.g., a display device, printer, or speaker). Such a system may also include one or more storage devices, such as magnetic disk drives, optical storage devices, and solid state storage devices, such as random access memory ("RAM") or read only memory ("ROM"), as well as removable media devices, memory cards, flash memory cards, and the like.

Such devices may also include a computer-readable storage media reader, a communication device (e.g., a modem, a network card (wireless or wired), an infrared communication device, etc.), and a working memory as described above. The computer-readable storage media reader can be connected with or configured to receive computer-readable storage media, which represent remote, local, fixed, and/or removable storage devices and storage media for temporarily and/or more permanently containing, storing, transmitting, and retrieving computer-readable information. The system and various devices will also typically include a number of software applications, modules, services or other elements located within at least one working memory device, including an operating system and application programs, such as a client application or web browser. It should be understood that alternative embodiments are possible with many variations from the above description. For example, customized hardware might also be used and/or particular elements might be implemented in hardware, software (including portable software, such as applets), or both. In addition, connections to other computing devices (such as network input/output devices) may be employed.

Various embodiments may also include receiving, transmitting or storing instructions and/or data implemented in accordance with the foregoing description upon a computer-readable medium. Storage media and computer-readable media for containing code or code portions may include any suitable media known or used in the art, including storage media and communication media, such as but not limited to volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage and/or transmission of information such as computer-readable instructions, data structures, program modules or other data, including RAM, ROM, electrically erasable programmable read-only memory ("EEPROM"), flash memory or other memory technology, compact disc read-only memory ("CD-ROM"), Digital Versatile Disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the system devices. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will appreciate other ways and/or methods to implement the various embodiments.

The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims that follow.

Other variations are within the spirit of the disclosure. Accordingly, while the disclosed technology is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined by the appended claims.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the disclosed embodiments (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. The term "connected," when unmodified and referring to physical connection, is to be construed as partially or wholly contained within, attached to, or connected together even if anything intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The use of the term "set" (e.g., "set of items") "or" subset "should be construed as a non-empty set comprising one or more members, unless otherwise indicated or contradicted by context. Furthermore, unless otherwise indicated or contradicted by context, the term "subset" of a corresponding set does not necessarily denote an appropriate subset of the corresponding set, but the subset and the corresponding set may be equal.

The operations of the processes described herein may be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The processes described herein (or variations and/or combinations thereof) may be performed under the control of one or more computer systems configured with executable instructions and may be implemented as code (e.g., executable instructions, one or more computer programs, or one or more applications) executed collectively on one or more processors, by hardware, or combinations thereof. The code may be stored on a computer-readable storage medium, for example, in the form of a computer program containing a plurality of instructions executable by one or more processors. The computer readable storage medium may be non-transitory.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

It is to be understood that the subject matter described herein is not limited in its application to the details of construction and the arrangement of components set forth in the description or illustrated in the drawings herein. The subject matter described herein is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the embodiments described above (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. While the dimensions, types of materials, and physical characteristics described herein are intended to define the parameters of the invention, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in which" are used as the plain-chinese equivalents of the respective terms "comprising" and "in which". Furthermore, in the claims, the terms "first," "second," and "third," etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Furthermore, the limitations of the claims are not written in component-plus-function format and are not intended to be interpreted based on clause 112, clause 6, volume 35 of the U.S. code, unless and until the limitations of these claims expressly use the phrase "component for … …," followed by a statement of function, and no further structure is intended.

The claims (modification according to treaty clause 19)

1. An Implantable Medical Device (IMD) comprising:

electrodes (116, 120) configured to be positioned proximate to an atrial (a) site and a Right Ventricular (RV) site;

a memory (260) storing program instructions;

one or more processors (220) configured to implement program instructions to:

detecting (302, 350) an atrial pacing (Ap) event or an atrial sensing (As) event;

measuring (306, 350, 404, 416) an AV interval corresponding to an interval between an Ap event or an As event and a sensed ventricular (Vs) event, the AV interval being associated with a current Heart Rate (HR);

automatically dynamically adjusting (354, 404, 416) a first AV delay directly based on the measured AV interval, wherein the first AV delay represents one of a pacing AV delay or a sensing AV delay (AVDp or AVDs);

identifying a scaling factor (358) between a base AS-Vs interval and a base Ap-Vs interval associated with a current HR;

calculating (360, 404, 416) a second AV delay associated with a current HR by scaling the first AV delay based on a scaling factor, wherein the second AV delay represents the other of a pacing AV delay or a sensing AV delay; and

managing pacing therapy utilized by the IMD associated with a current HR based on the first AV delay and the second AV delay.

2. The IMD of claim 1, wherein the measured AV interval represents a measured As-Vs interval, and the first AV delay represents sensed AV delays (AVDs) calculated (354) by subtracting an offset from the measured As-Vs interval.

3. The IMD of claim 2, wherein the second AV delay represents a pacing AV delay (AVDp) calculated (360) by multiplying or dividing AVDs by a scaling factor.

4. The IMD of claim 1, wherein the measured AV interval represents a measured Ap-Vs interval, the first AV delay represents a pacing AV delay (AVDp) calculated (354) by subtracting an offset from the measured Ap-Vs interval.

5. The IMD of claim 4, wherein the second AV delay represents sensed AV delays (AVDs) calculated (360) by multiplying or dividing AVDp by a scaling factor.

6. The IMD of claim 1, wherein the one or more processors are further configured to measure (306) a base As-Vs interval and a base Ap-Vs interval during a common base HR range (308); and storing (314) the scaling factor in association with the base HR range, wherein the identifying operation further comprises identifying the scaling factor based on the current HR and the base HR range.

7. The IMD of claim 6, wherein the one or more processors are further configured to repeat (312) the measuring and storing operations associated with different base HR ranges to obtain a plurality of base As-Vs intervals and base Ap-Vs intervals associated with the different base HR ranges, wherein the identifying operation includes identifying a selected base HR range corresponding to the current HR from the base HR ranges and calculating the second AV delay using a scaling factor associated with the selected base HR range.

8. The IMD of claim 1, wherein the one or more processors (235) are further configured to, during a search window, extend (406) the first AV delay and the second AV delay to correspond to a default search AV delay (AVD)_search) (ii) a Sensing cardiac activity for a predetermined number of heart beats during a search window; identifying whether cardiac activity is indicative of a conduction block condition or a non-conduction block condition; and repeating the determining, calculating, and adjusting operations (235) only when a non-conduction block condition is identified.