阅读说明：本技术 体腔中的流动调节 (Flow regulation in body cavities ) 是由 S·卡拉瓦尼 E·泰奇曼 于 2018-05-31 设计创作，主要内容包括：本文描述的装置和方法包括可植入体腔流体流动调节器,其包括由间隙与下游流动减速器隔开的上游流动加速器。间隙是从分支内腔将附加流体夹带到从上游流动加速器流向下游流动减速器的流体流动的路径。(The devices and methods described herein include an implantable lumen fluid flow regulator that includes an upstream flow accelerator separated from a downstream flow reducer by a gap. The gap is the path that entrains additional fluid from the branch lumen to the fluid flow from the upstream flow accelerator to the downstream flow reducer.)

1. An implantable device for modifying fluid flow through a body lumen coupled to a branch lumen, the implantable device comprising:

a flow conditioner configured to be implanted within the body lumen, the flow conditioner comprising an upstream component separated from a downstream component by a gap, the upstream component having an inlet, an outlet, and a cross-sectional flow area that converges from the inlet to the outlet, the downstream component having an inlet, an outlet, and a cross-sectional flow area that diverges from the inlet to the outlet, a distance between the outlet of the upstream component and the inlet of the downstream component being less than 15mm, wherein the gap defines a path that communicates with the branched lumens,

wherein the flow conditioner is configured to accelerate a fluid flow through the upstream component toward the downstream component to generate a low pressure region near the gap and entrain additional fluid into the fluid flow as the fluid flow enters the inlet of the downstream component.

2. The implantable device of claim 1, wherein the cross-sectional flow area at the outlet of the upstream component is less than the cross-sectional flow area at the inlet of the downstream component.

3. The implantable device of claim 1, wherein the outlet of the upstream component is positioned downstream of a location where the branch lumen first intersects the body lumen.

4. The implantable device of claim 1, wherein the gap begins downstream of a location where the branch lumen first intersects the body lumen.

5. The implantable device of claim 1, wherein the upstream and downstream components share a common collinear flow axis with a flow axis of the body lumen.

6. The implantable device of claim 1, wherein the outlet of the upstream component is positioned downstream of the inlet of the downstream component.

7. The implantable device of claim 1, wherein the upstream component is coupled with the downstream component via a fluid flow structure defining the gap,

wherein the upstream component, the downstream component, and the fluid flow structure are formed from a single frame.

8. The implantable device of claim 7, wherein the fluid flow structure extends outwardly from the upstream and downstream components such that the fluid flow structure contacts an inner wall of the body lumen.

9. The implantable device of claim 7, wherein a junction between the fluid flow structure and at least one of the upstream or downstream components has an S-shaped curvilinear shape.

10. The implantable device of claim 1, wherein the downstream component has a length greater than a length of the upstream component.

11. The implantable device of claim 1, wherein an average convergence angle of the upstream component is greater than an average divergence angle of the downstream component.

12. The implantable device of claim 1, wherein the upstream component comprises a nozzle that accelerates the fluid flow through the upstream component and the downstream component comprises a diffuser that decelerates the fluid flow with entrained additional fluid through the downstream component.

13. An implantable device for modifying fluid flow through a body lumen coupled to a branch lumen, the implantable device comprising:

a flow conditioner configured to be implanted within the body lumen, the flow conditioner comprising an upstream component separated from a downstream component by a gap, the upstream component having an inlet, an outlet, and a cross-sectional flow area that converges from the inlet to the outlet, the downstream component having an inlet, an outlet, and a cross-sectional flow area that diverges from the inlet to the outlet, the cross-sectional flow area at the outlet being less than the cross-sectional flow area at the inlet, wherein the gap defines a path that communicates with the branched lumen,

wherein the flow conditioner is configured to accelerate a fluid flow through the upstream component toward the downstream component to generate a low pressure region near the gap and entrain additional fluid into the fluid flow as the fluid flow enters the inlet of the downstream component.

14. The implantable device of claim 13, the outlet of the upstream component being positioned downstream of where the branch lumen first intersects the body lumen.

15. The implantable device of claim 13, wherein the gap begins downstream of a location where the branch lumen first intersects the body lumen.

16. The implantable device of claim 13, wherein the outlet of the upstream component is positioned downstream of the inlet of the downstream component.

17. The implantable device of claim 13, wherein the upstream component is coupled with the downstream component via a fluid flow structure defining the gap.

18. The implantable device of claim 13, wherein the flow modulator is formed from a metal frame.

19. The implantable device of claim 18, wherein the metal frame is coated with a biocompatible material at the upstream and downstream components.

20. A method for modifying fluid flow through a body lumen coupled to a branch lumen, the method comprising:

implanting a flow modulator within a body lumen, the flow modulator comprising an upstream component separated from a downstream component by a gap, the upstream component implanted in a first body lumen portion and having an inlet, an outlet, and a cross-sectional flow area that converges from the inlet to the outlet, the downstream component implanted in a second body lumen portion and having an inlet, an outlet, and a cross-sectional flow area that diverges from the inlet to the outlet, and the gap positioned where the branch lumens intersect the body lumen and the outlet positioned downstream of where the branch lumens first intersect the body lumen; and

accelerating a fluid flow through the upstream component toward the downstream component to create a low pressure region near the gap and entraining additional fluid into the fluid flow as the fluid flow enters the inlet of the downstream component.

21. The method of claim 20, wherein implanting the flow regulator within the body lumen comprises: implanting the upstream component into an inferior vena cava such that the inlet is upstream of a branch of a renal vein and the downstream component is in the inferior vena cava such that the exit port is downstream of the branch of the renal vein, wherein the gap is at the branch of the renal vein, thereby drawing blood into the renal vein and improving renal function.

22. The method of claim 21, wherein drawing the blood into the renal vein to improve renal function further reduces excess fluid to treat heart failure.

23. The method of claim 20, wherein the flow regulator regulates fluid flow without any input from an external energy source.

24. The method of claim 20, wherein the flow conditioner regulates fluid flow without any moving parts.

Technical Field

The present invention relates generally to devices and methods for modifying flow in a body lumen, such as devices and methods for creating a pressure differential at lumens branching off from other lumens and/or entraining fluid for enhancing or regulating fluid flow to treat different disorders or diseases.

Background

Heart failure is a physiological state in which cardiac output is insufficient to meet physical and pulmonary demands. Patients with any of a variety of forms of heart failure are prone to increased fluid accumulation in the body. Congestive Heart Failure (CHF) occurs when cardiac output is relatively low and the body becomes engorged with blood. There are many potential causes of CHF, including myocardial infarction, coronary artery disease, valve disease, and myocarditis. Chronic heart failure is associated with neurohormonal activation and altered autonomic control. While these compensatory neurohormonal mechanisms provide valuable support to the heart under normal physiological conditions, they also play an important role in the development and subsequent progression of CHF. For example, one of the major compensatory mechanisms of the body for reducing CHF blood flow is to increase the amount of salt and water retained by the kidneys. Retaining salt and water rather than excreting it into the urine increases blood volume in the bloodstream and helps maintain blood pressure. However, larger amounts of blood can also stretch the heart muscle, enlarging the heart chamber, especially the ventricles. Over a certain amount of stretching, the contraction of the heart may be reduced and heart failure may worsen. Another compensation mechanism is vasoconstriction of the arterial system. This mechanism, similar to the retention of salt and water, raises blood pressure to help maintain adequate perfusion.

Glomerular Filtration Rate (GFR), the rate at which blood is filtered by the kidney, is commonly used to quantify kidney function and, thus, the extent of renal disease in a patient. Individuals with normal renal function have a GFR of at least 90mL/min with no signs of renal damage. Progression of kidney disease is indicated by decreased GFR, where GFR below 15mL/min generally indicates that the patient has End Stage Renal Disease (ESRD), which is complete failure of the kidney to remove waste or concentrate urine.

Cardiovascular problems, such as, but not limited to, inadequate blood flow or chronic hypertension, can lead to fluid retention in the kidney, chronic kidney disease, reduced GFR, renal failure, or even ESRD. For example, hypertension is considered the second most common cause of renal failure (second only to diabetes). It is estimated that hypertension causes renal impairment and reduces GFR.

Accordingly, it is desirable to provide devices and methods for improving blood flow to prevent disease, improve body function, and/or treat conditions that would benefit from regulated fluid flow. For example, it is desirable to treat heart failure, treat hypertension, prevent renal disease, improve kidney function, and/or prevent blood clots from flowing through the vasculature to sensitive parts of the body, such as the brain, in order to prevent stroke.

Disclosure of Invention

The present invention seeks to provide devices and methods for modifying flow in a body lumen, as described in more detail below. For example, devices and methods are provided for creating pressure differentials and/or fluid entrainment at lumens branching from other lumens for enhancing or regulating fluid flow to treat different disorders or diseases.

The apparatus and method of the present invention have many applications. For example, the device may be used to reduce pressure and improve flow, thereby improving flow in a narrow body lumen. It can also be used in the aortic arch to reduce systolic pressure peaks in the brain or to transfer emboli to other parts of the body (e.g. the legs) and thereby reduce the risk of stroke. The device may also be installed in a bifurcation (e.g., in a brachiocephalic vessel) to reduce peak pressure gradients or to divert emboli with little energy loss.

The devices and methods of the present invention have particular application in the treatment of blood entering and exiting the kidney. According to one embodiment, the device is configured to be installed near one of the renal arteries or near a renal vein branch in the inferior vena cava or in one of the renal veins.

When installed in the inferior vena cava or renal vein, the device can create a region of increased blood flow velocity and decreased pressure (due to bernoulli effect or other factors) in the inferior vena cava or renal vein. In this way, blood may be drawn from the kidney into the renal vein and then into the inferior vena cava, thereby improving kidney function and reducing necrotic damage to the kidney.

When installed in or near the renal vein, the device of the present invention can improve renal function by improving the net filtered overpressure, which is glomerular capillary blood pressure- (plasma-colloid osmotic pressure + bowman capsule hydrostatic pressure), e.g., 55 mmHg- (30mm Hg +15mm Hg) ═ 10mm Hg. Thus, the devices and methods of the present invention provide improvements over existing therapies, such as diuretics (although the present invention may be used in addition to diuretics), Angiotensin Converting Enzyme Inhibitors (ACEIs), and Angiotensin Receptor Blockers (ARBs), which may have deleterious effects on kidney function. When used in conjunction with current treatment modalities such as diuretics, it is expected that the devices and methods of the present invention will improve the response to diuretics and reduce the dosage required to obtain the therapeutic benefits of such previously known therapies without the disadvantages of these prior therapies.

The devices and methods of the present invention can be used to transfer blood flow from the kidney to the inferior vena cava with little energy loss. For example, a significantly greater increase in blood flow may be achieved with less energy loss due to pressure drop and other fluid factors. This flow diversion from the kidneys has little energy loss to increase blood flow, and is expected to treat conditions such as heart failure and/or hypertension.

Note that there is a significant difference between using upstream nozzles without a downstream flow reducer (such as a diffuser). If only one upstream nozzle is placed in the flow path, significant energy losses can occur downstream of the nozzle due to sudden expansion of the flow. However, by using a downstream flow reducer (such as a diffuser), energy losses can be significantly reduced. This brings about another advantage: since the energy loss is significantly reduced, the additional flow into the gap is effectively added to the flow from the upstream flow accelerator.

In addition, when used with a downstream flow reducer, it is desirable that the present invention provide an optimal configuration for an upstream flow accelerator. For example, the distance between the outlet of the upstream flow accelerator and the inlet of the downstream flow reducer should be less than a predetermined length to reduce the pressure at the gap between the outlet and the inlet.

When installed in the renal artery, the device may reduce the pressure applied to the kidney. Without being bound by any theory, hypertension may damage blood vessels and filters in the kidney, making it difficult to remove waste products from the body. By reducing the pressure in the renal artery, the filtration rate improves. Although it may be possible to reduce perfusion pressure, the filtration rate will increase as overall renal function is more effective.

Note that the fluid flow regulator of the present invention can regulate fluid flow without any input from an external energy source such as a fan, motor, etc., and without any moving parts. The structure of the device of the present invention transfers energy from one lumen flow to a different lumen flow with minimal flow energy loss.

According to an aspect of the present invention, an implantable device is provided for modifying fluid flow through a body lumen (e.g., inferior vena cava) coupled to a branch lumen(s) (e.g., renal vein (s)). The implantable device includes a flow regulator configured to be implanted within a body lumen. The flow conditioner preferably has an upstream component separated from a downstream component by a gap. The flow conditioner may be formed as a single unit (e.g., formed from a single frame) or as multiple units. The upstream component has an inlet, an outlet, and a cross-sectional flow area that preferably converges from the inlet toward the outlet. The downstream component has an inlet, an outlet and a cross-sectional flow area that preferably diverges from the inlet toward the outlet. The gap defines a path in communication with the branch lumen,

the flow conditioner preferably accelerates fluid flow through the upstream component toward the downstream component to create a low pressure region near the gap and entrain additional fluid into the fluid flow as it enters the inlet of the downstream component.

The outlet of the upstream component is preferably spaced a suitable distance from the inlet of the downstream component to increase flow within the branching chamber(s) while minimizing pressure losses. For example, the distance from the outlet to the inlet may be less than 15 mm.

According to one aspect, the cross-sectional flow area at the outlet of the upstream component is less than the cross-sectional flow area at the inlet of the downstream component. The outlet of the upstream component may be positioned downstream of the location where the branch lumen first intersects the body lumen. The gap may extend downstream from a location where the branch lumen first intersects the body lumen. The upstream and downstream components may share a flow axis that is collinear with a flow axis of the body cavity. The outlet of the upstream component may be positioned downstream of the inlet of the downstream component.

In one example, an upstream component is coupled to a downstream component via a fluid flow structure defining a gap. The upstream component, the downstream component, and the fluid flow structure may be formed from a single frame. The fluid flow structure may extend outwardly from the upstream and downstream components such that the fluid flow structure contacts an inner wall of the body cavity. The junction between the fluid flow structure and the upstream and/or downstream components may have a curved shape, such as an S-shaped curvilinear shape.

According to one aspect, the length of the downstream component is greater than the length of the upstream component. The average convergence angle of the upstream components may be greater than the average divergence angle of the downstream components. The upstream component may include a nozzle that accelerates the fluid flow through the upstream component, and the downstream component may include a diffuser that decelerates the fluid flow with entrained additional fluid passing through the downstream component.

The flow conditioner may be formed of a metal frame. The metal frame may be coated with a biocompatible material at the upstream and downstream components. In one example, the uncoated portion of the metal frame between the upstream and downstream components defines a gap that allows fluid from the branch lumen(s) to entrain fluid flow through the flow conditioner.

According to another aspect, a method for modifying fluid flow through a body lumen coupled to a branch lumen is provided. The method may include implanting a flow modulator within a body cavity, the flow modulator including an upstream component separated by a gap from a downstream component, the upstream component being implanted in a first body cavity portion and having an inlet, an outlet, and a cross-sectional flow area that converges from the inlet toward the outlet, and the downstream component being implanted in a second body cavity portion and having an inlet, an exit, and a cross-sectional flow area that diverges from the inlet toward the exit. The gap may be positioned where the branch lumen intersects the body lumen, and the outlet may be positioned downstream of where the branch lumen first intersects the body lumen. The method may include accelerating fluid flow through the upstream component toward the downstream component to create a low pressure region near the gap and entraining additional fluid into the fluid flow as the fluid flow enters the inlet of the downstream component.

Implanting the flow regulator within the body lumen may include implanting an upstream component in the inferior vena cava such that the inlet is located upstream of the branch of the renal vein(s) and a downstream component in the inferior vena cava such that the outlet is located downstream of the branch of the renal vein(s), wherein the gap is located at the branch of the renal vein(s), thereby drawing blood from the renal vein(s) into the inferior vena cava and improving kidney function. Drawing blood from the renal vein(s) to the inferior vena cava to improve kidney function can further reduce excess fluid for treating heart failure.

The flow regulator can regulate fluid flow without any input from an external energy source. The flow regulator can regulate fluid flow without the need for any moving parts.

There is thus provided, in accordance with an embodiment of the present invention, a system, including a body cavity fluid flow conditioner including an upstream flow accelerator separated from a downstream flow reducer by a gap, wherein the gap is a path for entrainment of additional fluid with fluid flowing from the upstream flow accelerator to the downstream flow reducer.

The gap may be located in a fluid flow structure that defines a boundary for the path to entrain additional fluid flow downstream of the flow reducer. The upstream flow accelerator may have a flow cross-section that converges in the downstream direction. The downstream flow reducer may have a flow cross-section that diverges in a downstream direction. The fluid flow structure may comprise one or more conduits that are not collinear with the direction of flow from the upstream flow accelerator to the downstream flow moderator. The upstream flow accelerator and the downstream flow reducer may share a common collinear flow axis. The fluid flow structure may or may not connect the upstream flow accelerator to the downstream flow reducer. The fluid flow structure may diverge outwardly in a direction away from a central axis of the fluid flow structure. The junction between the fluid flow structure and at least one of the upstream flow accelerator and the downstream flow reducer may be curved.

According to an embodiment of the invention, there is provided a method for modifying fluid flow through a body cavity, the method comprising installing a fluid flow conditioner in the body, the fluid flow conditioner comprising an upstream flow accelerator separated from a downstream flow reducer by a gap, the upstream flow accelerator being installed in a first cavity portion, the downstream flow reducer being installed in a second cavity portion, and the gap being located in a branch cavity inclined relative to the first and second cavity portions, wherein when fluid flows from the upstream flow accelerator to the downstream flow reducer, additional fluid is entrained into the gap and added to the fluid flowing from the upstream flow accelerator to the downstream flow reducer.

In one method, a fluid flow regulator is installed near the renal artery to improve renal function by reducing renal perfusion pressure.

In one method, a fluid flow regulator is installed near the bifurcation to divert emboli from the bifurcation.

In one approach, a fluid flow regulator is installed in the aortic arch to reduce peak systolic pressure.

Drawings

The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a schematic illustration of a fluid flow regulator constructed and operative in accordance with a non-limiting embodiment of the present invention;

FIG. 2 is a side cross-sectional view of a fluid flow regulator constructed and operative in accordance with another non-limiting embodiment of the present invention;

3A-19 are schematic illustrations of different fluid flow regulators of the present invention, some of which are shown installed in various body lumens, according to a non-limiting embodiment of the present invention;

FIGS. 20 and 21 are side views of an exemplary flow accelerator constructed in accordance with the principles of the present invention;

FIG. 22 is a schematic view of a fluid flow regulator according to another non-limiting embodiment of the present invention, and includes a pump (downstream or upstream);

FIG. 23 is a schematic view of a fluid flow regulator installed in an aneurysm, according to a non-limiting embodiment of the present invention;

FIG. 24 is a schematic view of a fluid flow conditioner according to another non-limiting embodiment of the present invention, wherein the outlet nozzle of the upstream flow accelerator enters the mouth of the downstream flow reducer;

FIG. 25 is a schematic view of a fluid flow conditioner having an upstream flow accelerator with a portion that is not in line with a downstream flow reducer, but is inclined relative thereto and may be mounted in a branch lumen, according to another non-limiting embodiment of the present invention;

FIG. 26 is a schematic view of a lumen support member for use with a fluid flow regulator in accordance with another non-limiting embodiment of the present invention;

FIG. 27 is a schematic view of a fluid flow moderator according to another non-limiting embodiment of the present invention in which the upstream flow accelerator and/or downstream flow reducer may not seal against the internal contours of a body cavity;

FIG. 28 is a schematic illustration of an asymmetric transition between an upstream flow accelerator and a downstream flow reducer in accordance with another non-limiting embodiment of the present invention;

FIGS. 29A and 29B are views of an upstream flow accelerator or a downstream flow reducer whose shape may be modified in accordance with another non-limiting embodiment of the invention, wherein FIG. 29B is a cross-sectional view 29A taken along line B-B in FIG. 29;

FIGS. 30-34 are schematic views of a fluid flow regulator, shown in a delivery and retraction type configuration, according to a non-limiting embodiment of the present invention; and

fig. 35-37E are the results of bench testing used to determine a preferred configuration of a flow conditioner constructed in accordance with the present invention.

Detailed Description

Devices and methods for modifying flow in a body lumen are provided herein. For example, devices and methods for creating pressure differentials and/or fluid entrainment at lumens branching from other lumens may be provided for enhancing or regulating fluid flow to treat different disorders or diseases.

Referring now to FIG. 1, there is illustrated a flow conditioner 10 constructed and operative in accordance with a non-limiting embodiment of the present invention.

The flow conditioner 10 includes an upstream component 12 separated from a downstream component 16 by a gap 14. The gap 14 is a path that diverts or entrains additional fluid into the fluid flow from the upstream component 12 to the downstream component 14. As will be explained below, the upstream and downstream components 12, 16 create a region of lower pressure near the gap 14 that preferably entrains fluid into the fluid flow flowing through the gap 14. Fluid entrainment is the transport of fluid by shear induced turbulence. In accordance with the principles of the present invention, such entrainment may help to transport blood or other bodily fluids to and from the region, thereby promoting better function of the organ (e.g., from the renal vein(s) to the inferior vena cava to promote better function of the kidney(s) to treat disorders and/or diseases, such as heart failure).

The upstream component 12 has an inlet 13 and an outlet 15, and preferably has a cross-sectional flow area that converges in a downstream direction (indicated by arrow 17) along part or all of the length of the upstream component 12, such as, but not limited to, to a nozzle. In this manner, the upstream component 12 acts to accelerate the flow of fluid through the upstream component 12. The downstream component 16 has an inlet 21 and an outlet 23, and preferably has a cross-sectional flow area that diverges in the downstream direction along a portion or the entire length of the downstream component 16, such as, but not limited to, a diffuser. In this manner, the downstream component 16 acts to decelerate the fluid flow through the downstream component 16. The distance between the outlet 15 and the inlet 21 is selected to create a low pressure region near the gap 14 while minimizing pressure losses and reducing resistance to fluid flow, such as renal blood flow, at the branch lumen(s). For example, as the data below indicates, an excessive distance can create significant pressure loss that can actually send flow in the branching lumen in the wrong direction. Applicants have found that using a maximum distance between the outlet 15 and the inlet 21 (e.g. less than 25mm, and more preferably less than 15mm when used at the renal vein) will improve the flow rate in the branch vessel(s) with relatively low pressure loss. The gap 14 also allows the flow conditioner 10 to entrain additional fluid into the fluid flow as it enters the inlet 21 of the downstream component 16.

PCT patent applications WO 2016/128983 and WO 2018/029688, and U.S. provisional application nos. 62/586,258 and 62/630,406, describe several converging and diverging structures that may be used to create a flow conditioner 10 according to the principles described herein, and the disclosure of each of them is incorporated herein by reference in its entirety. Other non-limiting converging and diverging configurations are shown in fig. 2-34. The present invention may be practiced with different types of converging and diverging configurations, such as, but not limited to, a Startleford motive nozzle (e.g., where the flow through the nozzle is at separate edges, which gives the diffuser the best length to efficiency ratio), a Deltaval nozzle (e.g., an asymmetric hourglass shape), a variable cross-sectional area nozzle and venturi, a canted nozzle and venturi, and the like. The central axis of the diverging portion may be aligned with or offset from the central axis of the converging portion.

The gap 14 may be located in a fluid flow structure 18, the fluid flow structure 18 defining a boundary of a path for diverting or entraining additional fluid to flow to the downstream component 16. The fluid flow structure 18 may include one or more conduits that are not collinear with the direction of flow (indicated by arrow 17) from the upstream component 12 to the downstream component 16. For example, the conduits of the fluid flow structure 18 may be perpendicular to the flow direction, or may be inclined at an angle, such as a 30 ° angle, a 45 ° angle, or any other suitable configuration.

In the embodiment of FIG. 1, the upstream and downstream components 12, 16 share a common collinear flow axis 19. However, the present invention is not limited to this configuration, and the upstream component 12 may be inclined with respect to the downstream component 16. The upstream and downstream components 12, 16 may lie along a continuous curved path.

The fluid flow structure 18 may or may not connect the upstream component 12 to the downstream component 16. For example, if the fluid flow structure 18 employs a conduit, the fluid flow structure 18 preferably connects the upstream component 12 to the downstream component 16. However, the fluid flow structure 18 as shown in FIG. 1 may not be a conduit, but two walls that are not connected to each other. In this example, the fluid flow structure 18 does not connect the upstream component 12 to the downstream component 16.

The upstream and downstream components 12, 16 and the fluid flow structure 18 may be constructed of known medically safe materials, such as stainless steel or nitinol grafts, stents (coated or uncoated), stent-grafts (coated or uncoated), catheters, and the like. The outer profile of any of the upstream component 12, downstream component 16, and fluid flow structure 18 may be sealed (such as by expansion against it) relative to the inner wall of the body cavity, or alternatively may not be sealed, depending on the particular application.

The flow modulator 10 is sized and shaped to be implanted in a body cavity. The flow modulator 10 may be compressible for delivery (e.g., percutaneous delivery within a delivery sheath) and may expand upon deployment (e.g., self-expand upon exposure from the tip of the delivery sheath or an expandable balloon). The flow modulator 10 may be inserted into the body cavity in an antegrade or retrograde fashion, and may be removed in an antegrade or retrograde fashion. The flow modulator may be used as an acute device to be removed after a few hours/days, as a long term permanent device or a device that can be implanted/retrieved after a long term. When used as an acute device, the flow modulator 10 may remain coupled to a delivery/retrieval device, e.g., a sheath and/or wire/shaft, throughout a short-term implantation procedure to facilitate delivery and retrieval of the device. The flow modulator 10 may be compressible within the body lumen to allow for flushing of any stagnant flow regions created near the flow modulator 10. For example, the diameter of the flow modulator 10 may be partially or completely reduced within the body lumen to allow blood to flow through stagnant flow regions. Preferably, once inflated, the flow modulator 10 is sized to contact the inner wall of the body lumen to anchor the flow modulator 10 in place. The flow modulator 10 is preferably formed from one or more frames and may be coated with one or more biocompatible materials. For example, the frame(s) may be formed of metal(s) (e.g., shape memory metal) or alloy(s) or a combination thereof (e.g., a stent made of stainless steel or nitinol or cobalt chromium). For some applications, the frame(s) may be formed in the manner of a braided stent. In the case of more than one frame, the frames may be joined together by a suitable technique such as welding. For example, the upstream and downstream components 12, 16 may be formed from a common frame or two frames that may be joined prior to implantation. The flow modulator 10 may be at least partially coated with a biocompatible covering material (although they may also be used as bare metal, uncoated stents). The biocompatible material may be a fabric and/or polymer, such as expanded polytetrafluoroethylene (ePTFE), woven, knitted and/or braided polyester, polyurethane, DACRON (polyethylene terephthalate), silicone, polycarbonate urethane, or pericardial tissue from equine, bovine or porcine origin. The biocompatible coating may impede or impede fluid flow when applied to the frame. The sequence of bonding and coating processes may be bonding prior to coating or coating prior to bonding. The biocompatible material may be coupled to the frame(s) via stitching, spraying, encapsulation, electrospinning, dip molding, and/or different techniques.

In a preferred embodiment, the biocompatible material is fluid impermeable. However, for some applications, the surface need not be impermeable, but rather have a sufficiently low permeability to substantially prevent any blood from flowing through the longitudinal portion of the body lumen via any flow path other than the flow channel defined by the inner surface of the flow modulator 10. For some applications, the permeability per unit length of each of the surfaces is less than 0.25 microns (i.e., between 0 and 0.25 microns), wherein the permeability per unit length is defined based on the following equation according to darcy's law: k/Δ x ═ V μ/Δ P, where k is permeability, Δ x is length (in meters), V is average velocity (in meters per second), μ is fluid viscosity (in pascal-seconds), and Δ P is pressure differential (in pascal).

Although the present invention is not limited by any theory, a simplified engineering explanation is now provided to help understand how the upstream and downstream components 12, 16 operate to create the reduced pressure at the gap 14.

Bernoulli's equation controls the relationship between fluid velocity and pressure (ignoring height differences):

p is pressure

Rho ═ density

Velocity V ═ velocity

Condition at the inlet (upstream part 12)

2-condition at the gap 14

Conservation of mass (same flow rate):

V₁·A₁＝V₂·A₂

a ═ flow cross section

E_LOSSLoss of energy

For example, if the flow regulator 10 is installed near the kidney with the upstream component 12 in the inferior vena cava, V₁And A₁The renal velocity and flow area at the inferior vena cava, respectively.

Flow velocity (V) at the gap₂) Designed to achieve the desired pressure reduction. For example, but not limited to, suction of 6-8mmHg can be achieved at a speed of 0.5 meters per second and 3 area ratios. In the case of installation near the kidney, renal function can be improved by improving renal perfusion pressure.

In another example, the flow conditioner 10 may be mounted near a branch to divert emboli from the branch. In another example, the flow modulator 10 may be installed in the aortic arch to reduce peak systolic pressure.

Referring now to FIG. 2, another version of the flow regulator 10 is shown, wherein like elements are represented by like numerals. In this version, the fluid flow structure 18 includes a central portion 20, which may be cylindrical, that connects the upstream component 12 to the downstream component 16. The fluid flow structure 18 extends outwardly from the outlet 15 of the upstream component 12 and the inlet 21 of the downstream component 16 such that the fluid flow structure 18 is sized to contact an inner wall of a body cavity. The central portion 20 may be formed with one or more apertures 22 to define the gap 14 for fluid communication with the branch lumens, such that additional fluid from the one or more branch lumens flows into the gap 14 and is added to the fluid flowing from the upstream component 12 to the downstream component 16.

Note that the junction 24 between the fluid flow structure 18 and the upstream component 12 and/or the downstream component 16 is curved. This may help simplify flow and prevent the generation of local turbulence or vortices that may adversely affect pressure or flow characteristics. It should also be noted that the fluid flow structure 18 may diverge outwardly (reference numeral 26) in a direction away from a central axis 28 of the fluid flow structure 18. Depending on the application, this divergence may be used to create different flow effects. The divergence also causes the upstream and downstream components 12, 16 to move closer to each other. For example, the junction 24 between the fluid flow structure 18 and the upstream and downstream components 12, 16 may be S-shaped to move the outlet 15 closer to the inlet 21 to minimize the distance between these portions of the fluid regulator 10.

As best shown in fig. 2, the fluid regulator 10 is formed from a frame 25 and coated with a biocompatible material 27. Potential materials for the frame 25 and biocompatible material 27 are as described above. In FIG. 2, the fluid regulator 10 is formed from a frame defining an upstream component 12, a gap 14, and a downstream component 16. The upstream component 12 is coated with a biocompatible material 27 to define a fluid flow path through the upstream component 12 such that fluid flowing through the body cavity enters the inlet 13, accelerates through the converging portion of the upstream component 12, and exits the outlet 15 into the portion of the fluid regulator 10 having the gap 14. At the gap 14, there is a low pressure region formed by the shape of the upstream and downstream components 12, 16. Further, additional fluid from the branch lumen(s) at the gap 12 is entrained into the fluid flow flowing from the outlet 15 to the inlet 21. The downstream component 16 is also coated with a biocompatible material 27 to define a fluid flow path through the downstream component 16 such that fluid flow from the outlet 12 enters the inlet 21 with additional fluid through the gap 14, decelerates through the diverging portion of the downstream component 16, and exits back into the body cavity from the outlet 23. In this example, the gap 14 is created by an uncoated portion of the frame 25.

The upstream component 12 may have a fixation region 29 sized for anchoring the upstream component 12 within a body lumen. The fixation region 29 is sized to contact the inner wall of the body lumen and preferably has a diameter that is sized to be equal to or slightly larger than the diameter of the body lumen. The fixation region 29 may have a constant diameter and a length suitable for anchoring the upstream component 12 in the body lumen. Similarly, the downstream component 16 may have a fixation region 30 sized for anchoring the downstream component 16 within another portion of the body lumen. The fixation region 30 is sized to contact the inner wall of the other portion of the body lumen and preferably has a diameter that is sized to be equal to or slightly larger than the diameter of that portion of the body lumen. The fixation region 30 may have a constant diameter and a length suitable for anchoring the downstream component 16 in a body lumen. Preferably, the fixation regions 29 and 30 are configured to seal the fluid regulator 10 within the body cavity such that fluid flows only into the fluid pathway created by the fluid regulator 10 and does not flow around the fixation region 29 or the fixation region 30. In fig. 2, the fluid flow structure 18 has the same diameter as the fixation regions 29 and 30, which may enhance anchoring immediately proximal and distal of the branch lumen(s) while positioning the gap 14 at the intersection between the body lumen and the branch lumen(s). In this manner, the fluid flow structure 18 forms one or more additional securing regions (illustratively, two additional securing regions) between the securing regions 29 and 30. As shown, the portion of the fluid flow structure 18 that is coated with the biocompatible material 27 (on the opposite side of the uncoated frame 25 that defines the gap 14) serves as a fixation/sealing area. Fluid flowing in the body cavity may be trapped between the outer surface of the upstream component 12 and the wall of the body cavity between the fixation region 29 and the upstream portion of the fluid flow structure 18. Additionally, or alternatively, fluid flowing in the body lumen may be captured between the outer surface of the downstream component 16 and the wall of the body lumen between the fixation region 30 and the downstream portion of the fluid flow structure 18.

Referring now to FIG. 3A, an exemplary flow conditioner according to a preferred embodiment is shown with symbols depicting the dimensions of the flow conditioner 10. The dimensions provided with respect to fig. 3 are for an embodiment in which the flow regulator 10 is configured for implantation in the inferior vena cava such that the inlet 13 of the upstream component 12 is upstream of the branch of the renal vein(s) and the downstream component 16 is in the inferior vena cava such that the exit 23 is downstream of the branch of the renal vein(s) and the gap 14 is at the branch of the renal vein(s). d1 is the diameter of the outlet 15 of the upstream component 12. d1 is selected to produce an injection velocity for a given device resistance. In chronic cases, d1 may be in the range of 4-8 mm. In the acute case, d1 is preferably in the range of 3-7 mm. d2 is the diameter of portal 13 in the deployed, expanded state, and may be in the range of 12-40 mm. l1 is the length of the fixation area 29 and may be in the range of 5-30 mm. l2 is the overall length of the upstream component 12 and may be in the range of 15 to 60 millimeters. x is the distance from the outlet 15 of the upstream part 12 to the inlet 21 of the downstream part. For x, a minimum distance from the outlet 15 to the inlet 21 will provide better performance for the downstream component 16, but the renal flow will be reduced due to the greater resistance to flow from the renal vein(s) to the downstream component 16. The distance x is preferably selected (e.g., in the range of-5-25 mm) to provide improved renal flow rate with minimal pressure loss.

As shown below, the distance x may be negative because the outlet 15 of the upstream component 12 may be positioned downstream of the inlet 21 of the downstream component 16. a is the distance from the outlet 15 of the upstream component 12 to the centerline of the branching lumen, e.g., the right renal vein, and may be in the range of-25-25 mm. L1 is the length of the fixed area 30 and may be in the range of 5-30 mm. L2 is the overall length of the downstream component 16. L2 is preferably greater than L2 because the diverging shape creates a much higher pressure loss than the converging shape. L2: L2 may be in the ratio of 1:1 to 3: 1. D1 is the diameter at the inlet 21 of the downstream component 16 and is preferably greater than d1.. thus, the cross-sectional flow area at the outlet 15 of the upstream component 12 is less than the cross-sectional flow area at the inlet 21 of the downstream component 16. D1 is selected to receive all fluid ejected from the outlet 15. D1: D1 may be 1:1, otherwise the cross-sectional flow area of the downstream component 12 should be less effective to reduce the fluid flow rate in the downstream component (as shown in the downstream component) and may be expected to reduce the fluid flow velocity in the downstream component 16, and may be more effectively in the downstream component 2-2 direction, and may be expected to reduce the flow rate of the fluid ejected from the downstream component 16 as the downstream component 16, and may be more effectively as the downstream component 16, and may be in the downstream component 16, and may be more effectively as shown in the downstream component 16, and may be more effectively as the downstream component 16, and may be more effectively as the downstream component 16, and may be more effectively as the downstream the flow rate of the downstream of the downstream component 16, and may be more effectively as shown, and.

The fluid regulator 10 of FIG. 3A may be formed from a frame defining an upstream component 12, a gap 14, and a downstream component 16. In this example, both the upstream and downstream components 12, 16 are coated with a biocompatible material, while the gap 14 is created by an uncoated portion of the frame.

Fig. 3B shows the flow regulator 10 of fig. 3A implanted in the inferior vena cava at the renal vein. The upstream component 12 is located in the inferior vena cava such that the inlet 13 is located upstream of the left and right renal vein branches, and the downstream component 16 is located in the inferior vena cava such that the outlet 23 is located downstream of the renal vein branches. Although the right and left renal veins are typically at different heights along the inferior vena cava, the gap 14 is typically positioned near the renal vein branches (or other branch lumens when used for other indications). For example, the gap 14 may begin where the renal vein first intersects the inferior vena cava, as shown. Additionally, as shown, the gap 14 may be disposed entirely within the intersection between the renal vein and the inferior vena cava. As shown, the outlet 15 of the upstream component 12 may be located downstream of where the renal vein first intersects the inferior vena cava. Thus, blood enters the fluid regulator 10 only at the inlet 13 and the gap 14 downstream of where the branch lumens first intersect the main lumen. As shown, the inlet 21 of the downstream component 16 may be positioned upstream of the intersection of the renal vein with the end of the inferior vena cava. The flow regulator 10 creates a reduced pressure at the gap 14 and increases the rate of blood flow to the gap 14. Entrainment may also help to transport blood from the kidneys to the gap 14. In this manner, the present invention may draw blood from the kidney into the renal vein and then into the inferior vena cava, thereby improving kidney function, reducing necrotic damage to the kidney, and/or treating heart failure.

Reference is now made to fig. 4-29B, which illustrate various flow regulators of the present invention, in accordance with a non-limiting embodiment of the present invention. Again, like elements are denoted by like numerals.

In FIG. 4, the flow conditioner 10 is configured similarly to the fluid conditioner of FIG. 3A, however, the flow conditioner 10 of FIG. 4 includes one or more openings 31 to prevent stagnant flow areas. Fluid entering the fluid regulator 10 flows out of the opening 31 and into the body cavity. The opening 31 serves as a flash flow passage for the fluid and may surround the entire circumference of the fluid regulator 10 or be a port. Either the upstream component 12 or the downstream component 16 or both (as shown) may include one or more openings 31. As shown, the openings 31 may be on a converging portion of the upstream component 12 and/or a diverging portion of the downstream component 16. When openings 31 are utilized, they are preferably at least on the downstream component 16, as the downstream component 16 is preferably longer than the upstream component 12, such that the downstream component 16 is more prone to larger stagnant flow areas.

Fig. 5 is a cross-sectional view of a fluid regulator 10 having a plurality of openings 31 that function as flash flow passages.

FIG. 6 illustrates the fluid regulator 10 wherein the outlet 15 of the upstream component 12 is positioned downstream of the inlet 21 of the downstream component 16. In this example, the distance x is negative and D1 is greater than D1, e.g., at least 1mm greater. As shown, both the outlet 15 and the inlet 21 may be located downstream of the intersection of the branch lumen(s) and the body lumen.

Fig. 7 shows the manner in which the diameter D1 at the inlet of the downstream component 16 is selected relative to the distance x of the outlet 15 of the upstream component 12 so as to receive all of the fluid ejected from the outlet 15. As shown, for larger distances x, D1 is larger to ensure receipt of the fluid ejected from upstream component 12.

FIG. 8 illustrates the fluid regulator 10 configured similarly to the fluid flow regulator 10 of FIGS. 2 and 3A, although the gap 14 is along a portion that extends radially outward from the outlet 15 of the upstream component 12. The gap 14 is formed along a curved portion (e.g., S-shaped) between the fluid flow structure 18 and the outlet 15. This curvature allows the downstream component 16 to approach the branch lumen(s). In addition, for simplicity and additional anchoring support, the fluid flow structure 18 is located downstream of the intersection between the branch lumen(s) and the body lumen. The fluid regulator 10 may be formed from a common frame (e.g., a single bracket design) that facilitates controlling the distance x between the outlet 15 and the inlet 21. The single structure also facilitates coaxial orientation, particularly for eccentric upstream and downstream components.

FIG. 9 shows a flow conditioner 10 that is similarly configured to the flow conditioner 10 of FIG. 8, except that the downstream component 16 includes a curved portion 32 (e.g., S-shaped) that extends radially outward to contact an inner wall of the body cavity. The downstream second bend in the downstream component 16 provides further radial force to enhance anchoring within the body lumen and also provides a longer diffuser for a given length. The flow modulator 10 may also include additional gap(s) so as not to occlude fluid flow from other branch vessels, such as gap 33 at the downstream end of the downstream component 16.

Referring now to fig. 10 and 11, which illustrate the flow conditioner 10 having a gap 14, the gap 14 is asymmetrically positioned with respect to the upstream and downstream components 12, 16. In other words, the gap 14 is not located along the axis of the main vessel between the upstream and downstream components 12, 16, but rather is offset toward one of the upstream and downstream components 12, 16.

Depending on the application, the left side structure of fig. 10 and 11 may be in an upstream or downstream direction; thus, the left structure is labeled 12 or 16 and the right structure is labeled 16 or 12.

Fig. 12 shows the configuration of the upstream component 12 or the downstream component 16 depending on the flow direction. The structure includes a relatively wide portion 35 that converges into a relatively narrow portion 36. The relatively narrow portion 36 extends into a diverging portion 37 which acts as a sealing portion.

Fig. 13 shows another configuration of the upstream component 12 or the downstream component 16 depending on the flow direction. The configuration of the converging portion 38 includes surfaces that curve back in opposite directions.

Fig. 14A and 14B show another configuration of the upstream component 12 or the downstream component 16. In such a configuration, the first bracket member 39 may be mounted to have converging and diverging portions (fig. 14A), and then the second bracket member 40 may be mounted over the first bracket member 39 to define the final converging and diverging shape. Fig. 14A may also be used as is without an additional bracket member. Note that the first stent member does not necessarily contact the second stent member (diffusion stent), and may be shorter than the stent members shown in the drawings.

Fig. 15 shows an alternative design in which the upstream part 12 is made up of a plurality of discrete objects 41, such as but not limited to spheres, balloons, rods, etc., that gradually increase in size to create a converging effect. Similarly, the downstream component 16 may be constructed from a plurality of discrete objects 41, such as, but not limited to, spheres, balloons, rods, and the like, that gradually decrease in size to produce a diverging effect. The discrete objects 41 may optionally be covered by a film 42 to provide a smooth flow surface.

FIG. 16 shows the flow modulator 10 of FIG. 2 installed in a body lumen 43 such that the gap 14 is located at the bifurcation 44.

FIG. 17 shows another embodiment of the flow modulator 10 installed in a body lumen 43 such that the gap 14 is at a bifurcation 44. In this embodiment, the fluid flow structure 18 includes an extension 46 disposed in the bifurcation 44. Instead of a sleeve-like extension 46, an opening in the stent graft at the bottom of the device (in the sense of fig. 17; it could, of course, be located at a different position than the "bottom") could be used. Alternatively, openings may be used at both the top and bottom, or openings or any other combination may be used at the top and bottom.

Fig. 18 shows the flow modulator of one of the embodiments installed in the aortic arch such that the gap 14 is located at the bifurcation of the carotid artery. This installation can be used to reduce peak pressure gradients or to divert emboli from the carotid artery with little pressure loss.

Figure 19 shows a flow regulator installed near the kidney. For example, the upstream component 12 may be installed in the inferior vena cava below (upstream) the renal vein branch, and the downstream component 16 may be installed in the inferior vena cava above (downstream) the renal vein branch. Gap 14 is located at the renal vein branch. The flow conditioner 10 creates a reduced pressure region near the gap 14 and increases the blood flow velocity at the gap 14. Entrainment may also help draw blood from the kidneys into the gap. In this manner, the present invention can draw blood from the kidney into the renal vein and then into the inferior vena cava, thereby improving kidney function and reducing necrotic damage to the kidney.

Referring now to FIG. 20, another configuration of upstream or downstream components depending on the direction of flow is shown. The structure includes an outer support 90 and an inner support 92. The outer support 90 may be cylindrical. The inner support 92 may include a relatively wide portion 93 that converges into a relatively narrow portion 94. The relatively narrow portion 94 extends with very little energy loss into the slightly diverging portion 95. The two stents may be joined together (such as, but not limited to, by welding or other suitable technique) and at least partially coated with a coating 96 (although they may also be used as bare metal, uncoated stents). The sequence of bonding and coating processes may be bonding before coating or coating before bonding.

Referring now to fig. 21, another version of the embodiment of fig. 20 is shown. In this version, the outer stent 90 is shorter such that the coating 96 is applied over the ends of the outer stent 90.

Referring now to FIG. 22, a flow conditioner 100 is shown according to another non-limiting embodiment of the present invention. The flow conditioner 100 includes a pump 102, such as, but not limited to, an axial flow pump, a centrifugal pump, a booster pump, a chopper pump, and the like. The pump 102 may be held in place by a bracket or may be coupled to a portion of the upstream component 12 or the downstream component 16. The pump 102 may be located downstream or upstream, depending on the particular application. For example, the pump 102 may be used to increase blood flow and filtration.

Any of the embodiments of the present invention may be used to divert emboli or other debris, thus eliminating the need for additional filtering means. One example is the use of upstream or downstream components to divert emboli or other debris at or near the carotid artery.

Referring now to fig. 23, there is shown the flow modulator 10 (or any other flow modulator of the present invention) installed in an aneurysm 101. The flow modulator is installed through the vessel and reduces pressure at the aneurysm site to help prevent the aneurysm from growing or rupturing and possibly reduce the size of the aneurysm. The flow regulator will work even without sealing the aneurysm.

If there are one or more side branch lumens at or near the aneurysm site, the device reduces pressure, but also allows blood flow to the side branch. This is in contrast to prior art circular stent grafts, which disadvantageously occlude the side branch. Without the side branch, the device only reduces pressure and does not increase blood flow.

A filter may optionally be used with the flow regulator to prevent embolic debris from flowing from the aneurysm to other blood vessels.

Referring now to FIG. 24, a flow conditioner 110 is shown according to another non-limiting embodiment of the present invention. The flow conditioner 110 includes an upstream member 112 having an outlet 113 and a downstream member 116 having an upstream diverging inlet 117. The outlet 113 enters the inlet 117 and this area serves as the gap 114. Outlet 113 may be coupled with support 115 to a portion of downstream component 116, e.g., so that outlet 113 is centered with respect to inlet 117. Alternatively, a separate support structure (not obstructing flow) may be used to support the outlet 113.

The straight portion in the downstream component 116 may help straighten the flow prior to flow diffusion and reduce flow separation from the diffuser wall, thereby reducing pressure losses.

Fig. 24 shows an example of the flow modulator 110 installed in a renal application. In this example, the upstream component 112 may be installed in the inferior vena cava upstream of the renal vein branch, and the downstream component 116 may be installed in the inferior vena cava downstream of the renal vein branch. Outlet 113 is also downstream of the renal vein branch. Similar to the embodiment of fig. 19, the flow regulator 110 creates a reduced pressure at the outlet 113 in the gap 114, which increases the blood flow velocity from the renal vein to the gap.

Referring now to FIG. 25, a flow conditioner 120 is shown according to another non-limiting embodiment of the present invention. The flow conditioner 120 includes an upstream component 122 having an outlet 123 and a downstream component 126. The upstream part 122 has a first portion 128 which is not in line with the downstream part 126 but is inclined relative thereto and may be mounted in a branched lumen, as shown in figure 15, the outlet 123 may be directed towards the centre of the inlet of the downstream part 126. The outlet 123 may be coupled with the support 125 to a portion of the downstream component 126, for example, to center the nozzle relative to the inlet. Alternatively, a separate support structure (which does not impede flow) may be used to support the outlet 123.

Referring now to FIG. 26, there is shown a lumen support member 130 with a flow conditioner 10 installed in accordance with another non-limiting embodiment of the present invention. The luminal support member 130 can be a stent body that helps support the body lumen from collapsing inward during decompression.

Reference is now made to fig. 27, which illustrates that in any of the embodiments, the upstream component 12 and/or the downstream component 16 may not seal against, but may be spaced from, the internal contours of the body cavity. This arrangement prevents, for example, blocking flow from the side branch 73. Although this may create a pressure loss, it still reduces the pressure compared to using only a nozzle, and it may improve flow out of the body lumen, for example, out of a vein.

Reference is now made to fig. 28, which illustrates that the transition between the upstream component 12 to the downstream component 16 (in the region of the gap 14) may be offset from the centerline C-C of the body lumen. In such embodiments, the transition between the upstream component 12 to the downstream component 16 is asymmetric with respect to the centerline of the body lumen. For example, if there is only one side branch, this may be advantageous — the asymmetry will favor the flow from the side branch; if there are two side branches, the asymmetry will favor flow from one of the side branches.

Reference is now made to fig. 29A and 29B, which illustrate an upstream or downstream component 80, the shape of which may be varied in accordance with another non-limiting embodiment of the present invention. The upstream and downstream components 80 may combine to form a nozzle/diffuser configuration with gaps between the nozzle/diffuser configurations, similar to the configurations described throughout this disclosure.

The accelerator or decelerator 80 may include one or more expandable members, such as end surfaces 82 and 84 coupled by an intermediate member 85, such as, but not limited to, an expandable balloon or balloon, which may be expanded or contracted by introducing or withdrawing fluid into or from the expandable members 82 and 84 (connected to a suitable fluid source, such as water, saline, air, etc.). Intermediate member 85 may be a covering material and/or may be preformed (e.g., cylindrical, such as a stent) to create radial forces on expandable members 82 and/or 84 to create a better seal. Changing the size of the expandable members 82 and 84 changes the flow characteristics through the device. For example, how much the device diverges or converges may be varied. The expandable members 82 and 84 may be connected by a longitudinal member 86, which longitudinal member 86 may also be expandable and thus may vary in size, such as may vary in length or thickness.

The device may be deployed in a contracted state and then expanded in situ. In examples where the upstream and downstream components are combined into one device, a multi-lumen catheter may be used to inflate/deflate each inflatable member, either simultaneously or separately from a common lumen in the catheter. After the patient reaches a stable condition, the device can be deflated or inflated as needed to accommodate the changing conditions. The device can be collapsed for removal from the body. The fluid reservoir may be implanted with the device for expansion of the device after installation in the body. As described above for other embodiments, the device may be held against the inner walls of the body lumen or may be separate therefrom.

As described above, the flow modulator 10 is sized and shaped to be implanted in a body cavity. The flow modulator 10 may be compressible for delivery (e.g., percutaneous delivery within a delivery sheath) and expandable once deployed (e.g., self-expanding upon exposure from the distal end of a delivery sheath or expandable balloon).

Referring now to fig. 30, the flow modulator 10 is shown in a compressed delivery configuration within a sheath 150, according to another non-limiting embodiment of the present invention. The flow modulator 10 may be coupled to the transition section 152 and/or the wire 154 to facilitate delivery to and retrieval from the body lumen. Transition portion 152 illustratively has a non-concentric conical shape to facilitate compression into sheath 150 and coupling to upstream portion 12, although transition portion 152 may be coupled to downstream portion 16. The wire 154 is coupled to the transition portion.

Fig. 31A and 31B illustrate the flow conditioner 10 in an expanded, deployed configuration outside the sheath 150. When the flow modulator 10 is exposed beyond the distal end of the sheath 150, the flow modulator 10 may transition to the expanded, deployed configuration. For example, the sheath 150 may be pulled proximally against the fixation plug in the sheath 150 to withdraw the flow regulator 10 at a target location within the body lumen (e.g., a location where the renal vein intersects the inferior vena cava).

The flow modulator 10 may be removed from a body cavity (e.g., inferior vena cava). For example, the sheath may be threaded over the wire 154, and the wire 154 may be secured in place (e.g., ex vivo fixation of the proximal end of the wire). The sheath is then pushed toward the transition section 152 to compress the flow conditioner 10 within the sheath. The flow modulator 10 and sheath are then removed from the patient.

Referring now to FIG. 32, a flow conditioner 10 is shown according to another non-limiting embodiment of the present invention. The flow conditioner 10 is similar to the flow conditioner 10 of fig. 3A, although the flow conditioner 10 of fig. 32 further includes a retrieval mechanism 160. The retrieval mechanism 160 may be coupled to the proximal end of the upstream member 12 as shown. In this manner, a retrieval device, such as a hook 166, may be coupled to the retrieval mechanism 160 to pull the retrieval mechanism toward the sheath 164 to compress the flow conditioner 10 into the sheath 164 for retrieval. For example, the retrieval mechanism 160 may be configured like a snare, wherein a plurality of arms are coupled to an end of the upstream member 12 and coupled together near a center of the flow path within the upstream member 12. The flow member 10 may be implanted with a retrieval mechanism 160 coupled thereto, or the retrieval mechanism 160 may be coupled to the flow conditioner 10 during a retrieval procedure. The flow conditioner 10 in fig. 32 also includes a retrieval mechanism 162 at the opposite end of the flow conditioner, for example, the retrieval mechanism 162 is coupled to the end of the downstream component 16. The retrieval mechanism 162 operates in the same manner as the retrieval mechanism 160. The use of two retrieval mechanisms may be particularly helpful when the flow conditioner 10 is formed of a braided structure, as the diameter of the structure decreases as the braid lengthens. Retrieval mechanisms 160 and/or 162 may also be used for partial retrieval. For example, the retrieval mechanisms 160 and/or 162 may be pulled in the direction(s) (simultaneously or non-simultaneously) away from the gap 14 to partially or completely reduce the diameter of the flow conditioner 10 within the body lumen. Such a reduction would allow any stagnant flow areas created adjacent the flow conditioner 10 to be flushed. The flow modulator 10 may then be completely removed, repositioned within the body lumen and expanded, or expanded in a previously deployed position within the body lumen.

Fig. 33A and 33B illustrate the hook 166 in a compressed state within the sheath 164 and in an expanded state outside the sheath 164 coupled to the retrieval mechanism 160.

Referring now to FIG. 34, a flow conditioner 10 is shown according to another non-limiting embodiment of the present invention. The flow conditioner 10 is similar to the flow conditioner 10 of fig. 3A, although the flow conditioner 10 of fig. 34 also includes a ring 172. In this illustration, the frame 168 is formed from a plurality of ribs and defines the upstream component 12 and the downstream component 16. The frame 168 may be formed from a shape memory material, such as a shape memory metal. The frame 168 is coated with a biocompatible material 170 at the upstream and downstream components 12, 16 to define a flow channel, and the uncoated portion of the frame 168 therebetween defines the gap 14. The ring 172 is disposed around a portion of the frame 168 and maintains the portion disposed in the frame 168 in a compressed configuration. For example, in the downward deployment state of FIG. 34, the ring 172 is disposed between the upstream component 12 and the downstream component 16 around a portion of the fluid regulator such that the frame 168 forms a converging cross-sectional flow area at the upstream component 12 and a diverging cross-sectional flow area at the downstream component 16. The ring 172 is configured to move along the frame 168 to transition the portion of the frame 168 disposed within the ring 172 from the expanded state to the contracted state. Shaft 174 may be coupled to ring 172 such that movement of shaft 174 moves ring 172 along frame 168.

The flow modulator 10 can be delivered in a compressed state within a sheath to a target location within a body lumen. Once properly positioned, the flow modulator 10 is exposed from the sheath (e.g., by pulling the sheath proximally while holding the flow modulator 10 in place), and the flow modulator 10 self-expands to the deployed configuration. The flow conditioner 10 may be partially withdrawn (e.g., compressed to allow for cleaning) and/or fully withdrawn by moving the ring 172 proximally (e.g., by pulling the shaft 174 proximally) to compress the upstream or downstream components 12, 16 to a diameter suitable for insertion within the sheath. The remainder of the flow modulator 10 may then be compressed within the sheath and removed from the body via the sheath.

FIG. 35 illustrates a bench test for determining the optimal configuration of a flow conditioner constructed in accordance with the present invention. In bench testing, the flow modulator was placed in the main lumen (to simulate the inferior vena cava) such that the gap was positioned in the branch lumen (to simulate the renal veins). The gantry model utilizes a constant steady flow in the main branch and is connected to an overflow trough to maintain a constant physiologic pressure. Water was used as the fluid and trends were verified using blood analogues. A side branch with controlled resistance was connected to the elevated tank (to simulate the renal filtration pressure). The resistance in the side branch is fixed at a rate to produce normal renal blood flow with normal net filtering pressure. As a result, when the pressure gradient between the renal bath to the main lumen is small, the fluid flow is low.

Three pressure sensors (shown in fig. 35 as P1, P2, and P3) were connected to the simulated IVC (upstream of the side branch, downstream of the side branch). Magnetic flow sensors are used to measure IVC flow. Kidney flow is measured by a digital weight scale with a computer interface via rs 232. Thus, the mass flow rate (or flow rate, since the density can be calculated) can be measured without generating an additional pressure loss.

Fig. 36 is a graph showing the results of one representative IVC flow rate (2 liters per minute (L/min)). The figure shows kidney flow in mL/min versus differential pressure in mmHg for the various configurations shown in figures 37A-37E. Data points 200 are for a nozzle and diffuser configuration (shown in fig. 37E) based on the flow conditioner principles described herein. In this example, the outlet inner diameter of the upstream nozzle is 5mm and the inlet inner diameter of the downstream diffuser is 5.5 mm. As shown in fig. 36, the kidney flow was highest for this configuration and the table below shows that the nozzle and diffuser configuration produced much less pressure loss than all other configurations. Data points 202 are for a single nozzle configuration (shown in fig. 37B). In the nozzle and diffuser configuration, the same upstream nozzle is used as the upstream nozzle. As shown in fig. 36, the kidney flow was lower than the nozzle/diffuser configuration, but higher than the other configurations, and the 11mmHg pressure loss shown in the table below was significantly greater than the pressure loss for the nozzle and diffuser configuration. Data point 204 is used for baseline, which means that the device (shown in fig. 37A) is not used. As shown in fig. 36, the nozzle and diffuser configuration based solely on the principles of the present invention is significantly superior to the baseline. Data points 206 are for two nozzles in the same direction (as shown in fig. 37C). As shown in fig. 36, the kidney flow is negative in nature, which will send blood flow in the renal vein in the wrong direction. In addition, the following table confirms that the pressure loss of 22mmHg is high. The same upstream nozzle as described above was used, and the outlet inner diameter of the downstream nozzle was 5 mm. Data points 208, 210, and 212 are for two nozzles in opposite directions, with distances between the outlet of the upstream nozzle and the inlet of the downstream nozzle of 35mm (shown in fig. 37D), 12mm, and 4mm, respectively. The same upstream nozzle as described above was used, and the inlet inner diameter of the downstream nozzle was 5 mm. For data point 208, which is 35mm away, the kidney flow is effectively negative, similar to data point 206, which would send blood flow in the renal vein in the wrong direction. In addition, the following table confirms that the pressure loss of 22mmHg is high. For data points 210 and 212, the kidney flow was approximately baseline or worse than baseline, and the pressure loss was as high as 14 mmHg.

Configuration of	Pressure loss [ mmHg ]]
		Nozzle and diffuser	5
Nozzle with a nozzle body	11
		2 the same direction of the nozzle	22
2 opposite direction distance of nozzle-35 mm	22
		2 opposite direction distance of nozzle-12 mm	14
2 opposite direction distance of nozzle-4 mm	14

Thus, the applicant has found that using the maximum distance between the outlet of the upstream component and the inlet of the downstream component will improve the flow velocity in the branch vessel(s) with a relatively low pressure loss. Too great a distance can cause significant pressure loss, in effect resulting in the blood flow being sent in the renal vein(s) in the wrong direction. In addition, other structural characteristics of the downstream component improve kidney flow at low pressure losses, such as the inner diameter at the inlet of the downstream component being greater than the inner diameter at the outlet of the upstream component, the length of the diverging region of the downstream component being greater than the length of the converging region of the upstream component, and/or the average diverging angle of the downstream component being less than the average converging angle of the upstream component.

While the preferred exemplary embodiments of the present invention have been described above, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the invention. It is intended that the appended claims cover all such changes and modifications that fall within the true spirit and scope of this present invention.