WO2002038085A1

WO2002038085A1 - Device and method for reducing blood pressure

Info

Publication number: WO2002038085A1
Application number: PCT/US2001/048106
Authority: WO
Inventors: Kenneth R. Kensey; Young Cho; Harold E. Clupper
Original assignee: Kensey Kenneth R; Young Cho; Clupper Harold E
Priority date: 2000-11-13
Filing date: 2001-11-08
Publication date: 2002-05-16
Also published as: AU2002229026A1

Abstract

An implantable intravascular device for diverting blood flow from the aorta into at least one renal artery of a living being to effect a reduction in the being's blood pressure. The device comprises an anchoring means and a blood flow diverting means located on the anchoring means. The blood flow diverting element is arranged for movement between a stowed position and an extended position to effect the controlled diversion of blood into the at least one renal artery. A method of lowering blood pressure of a living being, the method comprising the steps of introducing a device into the aorta of a living being adjacent at least one renal artery whereupon the device increases the flow of blood to the at least one renal artery.

Description

DEVICE AND METHOD FOR REDUCING BLOOD PRESSURE

SPECIFICATION

This invention relates generally to medical devices and more particularly to devices including implantable devices for diverting and/or regulating blood flow to at least one renal artery.

High blood pressure is a serious health problem. In the United States alone, it is estimated that 60,130,000 patients have hypertension. Conventional methods existing for reducing hypertension usually involve introducing into the body of a living being pharmaceutical compositions or compositions of naturally occurring ingredients to adjust the heart rate. Angiotensin converting enzyme inhibitors are very popular and widely used in treating high blood pressure. These drugs are also often used in the treatment of diabetic kidney disease. Other methods for reducing hypertension include cardiopulmonary bypass surgery.

Considering the large size of the renal arteries, it has been estimated that these vessels carry approximately twenty percent of the total cardiac output to the kidneys. In young adults, approximately 1100 ml of blood pass through the two kidneys each minute. As part of their normal function, kidneys control the various ways oxygen supply to the brain is increased. For example, through the release of certain hormones, the kidneys can elevate blood pressure throughout the body to increase the supply of oxygen to the brain. However, this elevation in blood pressure can also result in hypertension. The manner in which the kidney determines what is happening in the rest of the body is by measuring the amount of blood it is getting. By diverting or increasing the amount of blood flow to the kidneys, one can "fool" the kidneys into thinking that a sufficient amount of oxygen is getting to the brain. Thus, the kidney will produce less hormones resulting in a reduction in hypertension.

Numerous patents have been issued disclosing various devices that are arranged for implantation within the human body for various purposes. For example, United States Patent No. 5,617,878 (Taheri) discloses a method for treating aortic occlusive disease in or around the intersection of the aorta and attendant arteries such as the renal arteries using both a graft and a stent. The graft is placed at the intersection of the two arteries using a balloon catheter. A cauterizing device is used to make an opening in the graft at a point corresponding to the intersection of the aortic and renal arteries. A stent is inserted into the graft and through the graft opening, the stent having an attachment mechanism to attach one end of the stent to the opening in the graft whereby the flow of blood at the intersection of the arteries is ensured. Any occluded area around the intersection of the aorta and renal artery is effectively repaired and strengthened.

United States Patent No. 4,501,263 (Harbuck) discloses a device and method for diverting blood flow from one blood vessel to another, such as from the hepatic artery to the portal vein for reducing hypertension of the liver. This patent also includes a method for implanting this device.

United States Patent No. 4,204,525 (Olson) discloses a method and device for continuously supplementing the flow pressure of venous blood to the liver which may be contained entirely internally of the patient so as to require no participation on his part or supplementary assistance. The method comprises supplying venous blood to the liver at a pressure in excess of the back pressure created by the liver by introducing arterial blood into the flow path of the venous blood in the portal vein.

United States Patent No. 5,643,340 (Nunokawa) discloses a synthetic vascular prosthesis which is formed by a first tube member and a second tube member. Both tube members having inner flow paths for blood. An end of the second tube member is connected with an outer surface of the first tube member and the inner flow path of the second tube member communicates with the inner flow path of the first tube member. The prosthesis is used to replace or bypass a lesioned portion of an in vivo blood vessel affected by an obstructive or distentive lesion.

While the aforementioned patents may be suitable for their intended purposes, the devices disclosed therein are not suitable for, intended for or arranged for placement within the aorta just downstream of the renal arteries for the purpose of lowering blood pressure within a living being by increasing blood flow through the renal arteries and to the kidneys. It would be a significant advance in the art to provide a device for accomplishing that end.

SUMMARY OF THE INVENTION

An implantable intravascular device for diverting blood flow from the aorta into at least one renal artery of a living being to effect a reduction in the being's blood pressure. The device comprises an anchoring means and a blood flow diverting means located on the anchoring means. The blood flow diverting means is arranged for movement between a stowed position and an extended position to effect the controlled diversion of blood into the at least one renal artery.

In a variation of a first exemplary embodiment, the blood flow diverting means may be moved into any one of a plurality of intermediately deployed positions between said stowed and extended positions.

In another variation of the first exemplary embodiment, the position of said at least one blood flow diverting means is controllable.

In another variation of the first exemplary embodiment, the at least one blood flow diverting means comprises a cupped or depressed portion disposed at a first end thereof.

In another variation of the first exemplary embodiment, the anchoring means comprises a generally cylindrical stent having a central axis and the at least one blood flow diverting means comprises a plurality of blood flow diverting elements arranged equidistantly around the central axis of said stent.

In another variation of the first exemplary embodiment, the at least one blood flow diverting means comprises a pair of opposed blood flow diverting elements.

In another variation of the first exemplary embodiment, the anchoring means comprises a generally cylindrical stent having a central axis and wherein when the at least one blood flow diverting element is in the stowed position, the cupped or depressed portion is oriented substantially parallel to the central axis and wherein when the at least one blood flow diverting element is in one of the intermediate deployed positions or is in the fully extended position, the cupped or depressed portion points inwardly towards the central axis.

In another variation of the first exemplary embodiment, the device additionally comprises a threaded adjustment screw for controlling the position of the blood flow diverting means.

In another variation of the first exemplary embodiment, when the blood flow diverting means is moved to any one of the plurality of intermediately deployed positions or to the extended position, the cupped or depressed portion is oriented at an approximately 45 degree angle with respect to the axis. The invention also describes a method of lowering blood pressure within a living being. The method comprises the step of introducing a device into the aorta of a living being adjacent at least one renal artery whereupon the device increases flow of blood to at least one renal artery to lower blood pressure within that living being.

Under a variation, the method comprises the additional step of controlling the amount of blood flow to the at least one renal artery.

Under another variation of the method, the device comprises a blood flow diverting element and the method includes the step of controlling the amount of blood flow to the at least one renal artery by moving the blood flow diverting element from a stowed position to an extended position to increase the flow of blood into the at least one renal artery.

Under another variation, the method includes the sub-step of moving the blood flow diverting element into any one of a plurality of intermediate positions between the stowed position and the extended position.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a longitudinal sectional view of the aorta of a living being at its junction with the renal arteries and showing a first exemplary embodiment of the present invention positioned therein, with the blood flow diverting elements of the embodiment shown in one of their deployed positions;

Fig. 1A is a sectional view taken along line 1A-1A of Fig. 1;

Fig. 2 is an enlarged elevational view of one of the blood flow diverting elements of the present invention shown in its stowed position;

Fig. 3 is a sectional view taken along line 3-3 of Fig. 2;

Fig. 4 is a view similar to Fig. 2 but showing one of the blood flow diverting elements of the present invention in its deployed position;

Fig. 5 is a sectional view taken along line 5-5 of Fig. 4;

Fig. 6 is a plan view of a portion of a stent forming a portion of the present invention shown in its erected state to illustrate its construction; and, Fig. 7 is a view similar to Fig. 6, but showing the stent secured in place at juxtaposed apices according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings where like reference numerals refer to like parts there is shown at 20 in Fig. 1 one exemplary embodiment of an intravascular device constructed in accordance with this invention for reducing blood pressure within a living being. As shown in Fig. 1, when installed within the body of the living being, the device 20 of the present invention is situated between the renal arteries 22 and the aortic-iliac bifurcation 27 just distal to the renal arteries 22. Hereinafter, this location is sometimes referred to as the target site. The device 20 comprises two major components: a self-expanding stent, indicated at 25, and one or more blood diverting assemblies, each indicated at 30.

There are many types of self-expanding stents disclosed in the prior art that would serve well as means for mounting the blood diverting assemblies 30 of the present invention and thus, any such stent may be utilized. In fact any stent, regardless of construction, geometry or operation, which is arranged to be deployed and erected or expanded in place can be used, although self-expanding stents offer the advantage of ease and simplicity of deployment. Moreover, the means for mounting the blood diverting assemblies 30 is not to be limited to stents. In fact, it is contemplated under this invention that a variety of structures and/or components other than stents could also serve well for locating the blood diverting assemblies 30 of the present invention within the aorta at its junction with the renal arteries. In other words, nothing in this disclosure should be construed as limiting the structure utilized for locating the blood diverting assemblies at the target site. The stent 25 is comprised of any suitable biocompatible material and is formed of any suitable construction. The stent shown and discussed in this specification is merely exemplary. For example, the stent 25 could be formed of a material and constructed in accordance with the teachings set forth in U.S. Patent No. 6,051,020 (Goicoechea et al), the disclosure of which is incorporated herein by reference. As shown in Fig. 6, the stent 25 is made by winding a single strand 32 of a shape memory wire, e.g., nitinol wire, onto a mandrel (not shown) to form a plurality of hoops, each hoop having an apex 33. The winding surface of the mandrel (not shown) is provided with a plurality of upstanding pins (not shown) to enable formation of the hoops and their corresponding apices 33. As shown in Fig. 6, the strand 32 is first wound to form a top tier indicated at 36a. Once the strand 32 is wound one full revolution around the mandrel, the top tier 36a is completed. Next, the strand 32 is looped upon itself, as indicated at 31a, and then dropped down to the next tier below, 36b. On the second tier 36b, the winding process is repeated. That is, once the strand 32 is wound one full revolution around the mandrel to complete the second tier 36b, as indicated at 31b, the strand 32 is dropped down to the next tier below, indicated at 36c. Thereafter, the strand 32 is wound as described above to form tiers 36c, 36d, 36e and 36f. Next, the wire 32 is annealed at any suitable temperature, e.g., 500° C for any suitable period of time, e.g., 60 minutes, and is then allowed to cool in air. The purpose of the annealing is so that the wire "remembers" its configuration as wound on the mandrel (not shown). It should be appreciated that other temperatures and durations for the annealing are included within the present invention provided the wire "remembers" its wound configuration.

Referring now to Fig. 7, after annealing and cooling, the wire is immersed in cold water, e.g., less than 10° C for about 5 minutes, and the wire 32 is then removed from the mandrel, and the juxtaposed apices 33 are secured to together by securing ties 40. Exemplary securing ties 40 could be polypropylene filaments. Each apex 33 of each hoop is tied to the juxtaposed apex 33. It will be appreciated, however, that in other embodiments of the invention, only some of the juxtaposed apices 33 may be secured in this way. In addition to polypropylene filaments, the securing ties 40 may comprise a suture material, for example, to tie the juxtaposed apices 33 together. Alternatively, the securing tie 40 may be a ring or staple formed of wire such as nitinol. As best illustrated in Fig. 1 A, once formed, the stent 25 is cylindrical in shape and includes a central axis and an outer wall formed of the wound strand 32.

Referring now to Fig. 1A and Figs. 2 through 5, the details of the blood diverting assembly 30 of the present invention are shown. Each blood diverting assembly 30 comprises one or more blood diverting elements 34 that includes a deflecting portion 50 that is adjoined to a shank portion 55. As best shown in Figs. 1 and 1 A, the deflecting portion 50 may be concave in shape. At this juncture, it is important to mention that the deflecting portion 50 is not limited to a concave shape, or for that matter to any particular construction or geometry. In fact, the deflecting portion 50 may be shaped in a myriad of other ways, e.g., convex, bulbous, rounded, squared, flat, triangular, or any other geometric configuration that results in altering the amount of blood that is diverted from the aorta 27 into the renal arteries 22. Also within the scope of this invention, the deflecting portion 50 could include one or more through openings, perforations or apertures that would affect the amount of blood being diverted from the aorta into the renal arteries. As shown in Figs. 1 through 5, two blood diverting elements 34 are shown mounted to the stent 25 which are oriented face-to-face. At this juncture it is important to mention that although the deflecting portion 50 and shank portion 55 are shown as being integral with each other, these components could also be distinct components joined to one another by any suitable means, e.g., welding. The deflecting portion 50 and the shank portion 55 may be formed of any suitable biocompatible material, e.g., flexible stainless steel.

The shank portion 55 includes an upper slot 60 and a lower slot 65. Referring now to Figs. 2 and 3, a front guide 70 and rear guide 75 are each provided with through openings 70a and 75a to enable passage of a wire 32 of the stent 25 therethrough to enable securement of the front and rear guides 70 and 75 to the stent 25. The front and rear guides 70 and 75 may be formed of any suitable biocompatible material, e.g., stainless steel. As best shown in Figs. 2 and 4, the front guide 70 is situated within the upper slot 60 of the blood diverting assembly 30 and the rear guide 75 is situated within the lower slot 65 of the blood diverting assembly 30 to hold the blood diverting elements 34 captive and to enable translational movement of the blood diverting elements 34 from a stowed position, as best shown in Figs. 2 and 3, to a fully extended position and to any desirable deployed position therebetween. Translational movement of the blood diverting element 34 from the stowed position to the fully extended position is along a path parallel to the central axis of the stent 25. As best shown in Figs. 4 and 5, the blood diverting elements 34 are deployed to a position between said stowed position and said fully extended position.

Referring again to Figs. 2 and 3, the rear guide 75 also serves as a bearing for an externally threaded adjustment screw 80 and permits the adjustment screw 80 to rotate but not translate therein. The adjustment screw 80 may be formed of any suitable biocompatible material, e.g., stainless steel, and is provided with a closed eye-loop 82 at one end to enable grasping and rotation of the adjustment screw 80 by any suitable biocompatible instrument, e.g., a flexible grasper (not shown) inserted into the body. Such a flexible grasper is well known in the art and may be of any suitable construction so long as it is flexible in lateral directions so that it can be steered through the body's vasculature to the aorta 27 at its junction with the renal arteries 22 and is rotatable so that it can be rotated for deployment of the blood diverting elements 34.

Rotation of the adjustment screw causes translational movement of the blood diverting element 34 in a manner to be explained below. An internally threaded block 85, formed of any suitable biocompatible material, e.g., stainless steel, is affixed to an end of the shank portion 55 opposite the deflecting portion 50. The externally threaded adjustment screw 80 is engageable with the internally threaded block 85 such that upon rotation of the adjustment screw, the blood diverting element 34 moves or translates from the stowed position, as best shown in Figs. 2 and 3, to a fully extended position and to any one of a plurality of intermediate deployed positions therebetween. As mentioned previously, Figs. 4 and 5 illustrate the blood diverting element 34 deployed from said stowed position to one of said intermediate deployed positions.

Referring again to Figs. 2 and 3, when the blood diverting element 34 is in the stowed position, the front guide 70 has the additional function of retaining the deflecting portion 50 in an upright orientation and against the framework of the stent 25. With the deflecting portion 50 retained in this upright orientation, the stent may be compressed so that its diameter is reduced so that the device 20 may be placed within a suitable insertion catheter (not shown) to enable delivery of the device 20 at the target site. Once located at the target site within the aorta, the stent 25 may be deployed from the insertion catheter (not shown). Upon deployment, the stent 25, by its natural tendency, will self-expand from its compressed condition and will engage itself against the wall of the aorta at the desired location. Optionally, barbs may be provided to facilitate securement of the stent 25 within the aorta 27. Thereafter, the grasping element (not shown), described above, may be introduced at the target site and used to engage the closed loops 82 of the adjustment screws 80 to deploy the blood diverting elements 34. As each blood diverting element 34 is deployed from the stowed position, the deflecting portion 50 moves from an upright orientation to an inclined orientation pointing towards the central axis of the stent 25. As is evident, each blood flow diverting element is deployable. Thus, one blood flow diverting element could be deployed while the other is retained in the stowed position to effect an increase of blood flow into one renal artery but not the other. The ability to independently deploy any one of the blood diverting elements could be desirable where a kidney associated with one of the renal arteries has been removed and it is desirable to divert blood to one remaining kidney.

As best shown in Figs. 1 and 1 A, once the blood diverting elements 34 are deployed, a significant portion of blood (indicated by arrows 39 ) flowing through the aorta 27 is diverted into the renal arteries 22. This increased flow of blood to the kidneys through the renal arteries 22 has the effect of lowering blood pressure. The position of the deflecting portions 50 may be adjusted by means previously discussed to adjust the amount of diverted flow of blood to the renal arteries. Alternatively, it is contemplated under the invention that a feedback mechanism or system could be employed in combination with the intravascular device 20 in a manner such that the system would monitor or detect blood pressure within the living being and in accordance with predetermined parameters defining a desired blood pressure level or goal, adjust the deployed position of the deflecting portions 50 to adjust upwardly or downwardly the level of blood pressure within the living being towards the desired blood pressure level.

There are several devices and methods shown and described in the prior art for delivering and deploying a self-expanding stent within the vasculature of a living being that would be suitable for delivering and deploying the device of the present invention at the target site. Some of these methods and devices such as insertion catheters are disclosed in U.S. Patent Nos. 5,464,449 (Ryan et al); 5,693,086 (Goicoechea et al); 5,552,883 (Slater et al.); 5,591,226 (Trerotola et al.); and, 5,484,444 (Braunschweiler et al).

When it becomes desirable or necessary, the device 20 may be easily removed from the inner wall of the aorta 27, by introduction of the insertion catheter (not shown) at the target site. Disposed within the insertion catheter are several grasping tools (not shown) each of which is arranged for grasping an apex 33 located on the bottom tier 36f to pull the device 20 of the present invention within the insertion device.

As should be appreciated from the foregoing, devices constructed in accordance with this invention increase the flow of blood through the renal arteries resulting in a reduction in blood pressure. While the disclosed embodiment is used for both renal arteries, if desired, it may be constructed and arranged for use with only one of the renal arteries. In any case, the subject invention accomplishes its end without necessitating the introduction of drugs, chemicals, etc., into the body to adjust the heart rate. Moreover, the device is simple in construction and easy to deploy and position within the aorta of a living being.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to without departing from the scope of the invention. Without further elaboration the foregoing will so fully illustrate my invention that others may, by applying current or future knowledge, adopt the same for use under various conditions of service.

Claims

CLAIMS What is claimed is:

1. An implantable intravascular device for diverting blood flow from the aorta into at least one renal artery of a living being to effect a reduction in the being's blood pressure, the at least one renal artery branching from the aorta to an associated kidney, said intravascular device comprising: a. an anchoring means; and, b. at least one blood flow diverting means located on said anchoring means, said at least one blood flow diverting means being arranged for movement between a stowed position and an extended position, said at least one blood flow diverting means when in said extended position serving to divert blood into the at least one renal artery to effect a reduction in the being's blood pressure.

2. The implantable intravascular device of Claim 1 wherein the position of said at least one blood flow diverting means is controllable.

3. The implantable intravascular device of Claim 1 wherein said blood flow diverting means may be moved into any one of a plurality of intermediately deployed positions between said stowed and extended positions.

4. The implantable intravascular device of Claim 3 wherein the position of said at least one blood flow diverting means is controllable.

5. The device of Claim 1 wherein said at least one blood flow diverting means comprises a cupped portion disposed at a first end thereof.

6. The device of Claim 1 wherein said anchoring means comprises a generally cylindrical stent having a central axis and wherein said at least one blood flow diverting means comprises a plurality of blood flow diverting elements arranged equidistantly around the central axis of said anchoring means.

7. The device of Claim 1 wherein said at least one blood flow diverting means comprises a pair of opposed blood flow diverting elements.

8. The device of Claim 5 wherein said anchoring means comprises a generally cylindrical stent having a central axis and wherein when said at least one blood flow diverting means is in said stowed position, said cupped portion is oriented substantially parallel to said central axis and wherein when said at least one blood flow diverting means is in one of said intermediate deployed positions or is in said fully extended position, said cupped portion points inwardly towards said central axis.

9. The device of Claim 2 additionally comprising an adjustment means for controlling the position of said at least one blood flow diverting means.

10. The device of Claim 9 wherein when said at least one blood flow diverting means is moved to any one of said plurality of intermediately deployed positions or to said extended position, said cupped portion is oriented at an approximately 45 degree angle with respect to said axis.

11. A method of lowering blood pressure of a living being, said method comprising the steps of introducing a device into the aorta of a living being adjacent at least one renal artery whereupon said device increases flow of blood to the at least one renal artery.

12. The method of Claim 11 additionally comprising the step of controlling the amount of blood flow to the at least one renal artery.

13. The method of Claim 12 wherein said device comprises a blood flow diverting means and wherein said step of controlling the amount of blood flow to the at least one renal artery comprises the sub-step of moving the blood flow diverting means from a stowed position to an extended position to increase the flow of blood into the at least one renal artery.

14. The method of Claim 13 wherein said sub-step of moving the blood flow diverting means from a stowed position to an extended position includes the sub-step of moving the blood flow diverting means into any one of a plurality of intermediate positions between said stowed position and said extended position.

15. An implantable intravascular device for diverting blood flow from the aorta into at least one renal artery of a living being to effect a reduction in the being's blood pressure, the at least one renal artery branching from the aorta to an associated kidney, said intravascular device comprising: a. a stent having a generally cylindrical wall and a central axis; and, b. at least one diverter located adjacent to the wall of said stent, said diverter being arranged for movement between a stowed position and an extended position, said diverter when in said extended position serving to divert blood into the at least one renal artery to effect a reduction in the being's blood pressure.

16. The implantable intravascular device of Claim 15 wherein the position of said at least one diverter is controllable.

17. The implantable intravascular device of Claim 15 wherein said at least one diverter may be moved into any one of a plurality of intermediately deployed positions between said stowed and extended positions.

18. The implantable intravascular device of Claim 17 wherein the position of said at least one diverter is controllable.

19. The device of Claim 15 wherein said at least one diverter comprises a cupped portion disposed at a first end thereof.

20. The device of Claim 15 wherein said at least one diverter comprises a plurality of diverters arranged equidistantly around the central axis of said stent.

21. The device of Claim 16 additionally comprising a threaded adjustment screw for controlling the position of said at least one diverter.