METHOD OF TREATING COPD WITH ARTIFICIAL ARTERIO-VENOUS FISTULA AND FLOW MEDIATING SYSTEMS

Abstract

A method for treatment of COPD, hypertension, and left ventricular hypertrophy, and chronic hypoxia including creation of an artificial arterio-venous fistula and installation of a flow mediating device proximate the fistula. The flow mediating device is operated to limit flow as medically indicated to provide the optimum amount of bypass flow.

Claims

1. A method of treating COPD in a patient, comprising: implanting a shunt between a first vessel and a second vessel such that an anatomical fistula forms, wherein blood flows through the shunt; evaluating the patient after a stabilization period following the creation of the anatomical fistula, wherein the stabilization period is sufficient to allow for long-term remodeling of a heart of the patient; adjusting the blood flow through the fistula by restricting flow through another region of the vasculature different from the shunt; and controlling bypass blood flow through the fistula to treat COPD.

2. The method of claim 1, further comprising determining a trade-off between a blood level, a cardiac output, and a heart rate of the patient.

3. The method of claim 1, wherein the anatomical fistula is a side-to-side fistula.

4. The method of claim 1, wherein blood flows through the shunt between the first vessel and the second vessel until a blood plasma oxygen level (PaO2) and mixed venous oxygen level (SvO2) increases between 20% to 25% relative to the blood flow without the shunt.

5. The method of claim 1, wherein adjusting the blood flow through the fistula by restricting flow through another region of the vasculature different from the shunt occurs until a blood plasma oxygen level (PaO2) and mixed venous oxygen level (SvO2) level are between 10% to 20%.

6. The method of claim 1, wherein the bypass blood flow is controlled with a flow mediating device, wherein the flow mediating device comprises an inflatable bladder system, and wherein the inflatable bladder system comprises an inflatable cuff configured to substantially surround a portion of the patient's vasculature proximate the fistula.

7. The method of claim 1, wherein the bypass blood flow is controlled with a flow mediating device, wherein the flow mediating device comprises an inflatable bladder, and wherein the inflatable bladder is configured to impinge upon a portion of the patient's vasculature proximate the fistula.

8. The method of claim 1, wherein controlling comprises operating a flow mediating device to mediate flow through the shunt.

9. The method of claim 1, wherein the bypass blood flow is controlled with a flow mediating device, and wherein the flow mediating device is positioned on the first or second vessel downstream from the fistula.

10. The method of claim 1, wherein the bypass blood flow is controlled with a flow mediating device, and wherein the flow mediating, device is positioned on the first or second vessel upstream from the fistula.

11. The method of claim 1, wherein the anatomical fistula forms between a femoral artery and femoral vein of the patient.

12. The method of claim 1, wherein the anatomical fistula forms between one of the following vein/artery pairs: the aorta and inferior vena cava, the femoral vein and the iliopopliteal vein or iliac vein, the carotid artery and the carotid vein or jugular vein, the brachial artery and brachial vein, and the brachio-cephallic artery and subclavian vein.

13. The method of claim 1, wherein the bypass blood flow is controlled with a flew mediating device, and wherein the flow mediating device is positioned on the external surface of the first or second vessel.

14. A method of treating COPD in a patient, comprising: implanting a shunt between a first vessel and a second vessel such that an anatomical fistula forms, wherein blood flows through the shunt; evaluating the patient after a stabilization period following the creation of the artificial fistula; adjusting the blood flow through the fistula by restricting flow through another region of the vasculature different from the shunt; determining a trade-off between a blood level, a cardiac output, and a heart rate of the patient; and controlling bypass blood flow through the fistula to treat COPD.

15. The method of claim 14, wherein the anatomical fistula is a side-to-side fistula.

16. The method of claim 14, wherein controlling comprises increasing the bypass blood flow such that cardiac output is increased.

17. The method of claim 14, wherein adjusting the blood flow comprises throttling the blood flow through the first or second vessel to restrict the bypass blood flow through the fistula.

18. The method of claim 14, wherein the bypass blood flow is controlled with a flow mediating device, and wherein the flow mediating device is positioned on the external surface of the first or second vessel.

19. The method of claim 14, wherein the bypass blood flow is controlled with a flow mediating device, and wherein the flow mediating device does not contact the blood flow of the vein or the artery.

20. A method of treating COPD in a patient, comprising: implanting a shunt between a first vessel and a second vessel of the patient; and installing a flow mediating device separate from the shunt, wherein the flow mediating device is in contact against the first or second vessel such that substantial blood flow through the fistula between the first and second vessels is maintained when the flow mediating device is in use.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 illustrates the method of creating an artificial arterio-venous fistula and controlling flow with a balloon impinging on the artery.

[0010] FIG. 2 is a detail view of the inflatable cuff and its associated components, installed over the femoral vein of the patient.

[0011] FIG. 3 illustrates installation of the cuff over the left femoral artery.

[0012] FIGS. 4, 5 and 6 illustrate use of bladder which merely impinges on the femoral vein to control bypass flow.

[0013] FIGS. 7 and 8 illustrate a bladder assembly which assists in operably coupling the bladder to the blood vessel.

[0014] FIG. 9 shows the bladder assembly of FIG. 8 disposed in impinging relationship with the anatomical fistula.

[0015] FIGS. 10 and 11 illustrate use of shunt with an integral bladder, which may be inflated to control flow through the shunt, as desired to affect the arterial bypass flow as treatment for COPD.

[0016] FIGS. 12 and 13 illustrate another mechanism for regulating fistula bypass flow, in which a membranous wall of the shunt may be magnetically drawn to control the size of the shunt lumen.

DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 illustrates the method of creating an artificial arterio-venous fistula and controlling flow with a balloon impinging on the artery. A portion of the vasculature of the patient 1 is shown, illustrating the left and right femoral artery/external femoral arteries 3L and 3R, the left and right common iliac arteries 4L and 4R, and the abdominal aorta 5. Portions of the venous system are also illustrated the vena cava 6, which runs parallel to the aorta, and is typically contiguous with the aorta, the left and right femoral veins 9L and 9R. An artificial arterio-venous fistula or side-to-side anastomosis 7 may be formed between the femoral vein and femoral artery on either side of the body, indicated as items 10R and 10L, or between the iliac artery and the femoral vein, and at locations within the aorta, as indicated at item 7. The artificial fistula may be maintained as an anatomical fistula, consisting of vascular tissue, if the local anatomy tends to heal to a stable and patent fistula, or it may be maintained by shunt or shunt rivet 8 as illustrated, or by an endoprosthesis (a vascular graft or stent graft) of significant length.

[0018] To regulate flow through the fistula, an inflatable cuff 11 is placed and implanted around the femoral vein, proximal to the fistula (closer to the heart relative to the fistula). The inflatable cuff is further illustrated in FIG. 2, which shows the inflatable cuff assembly which includes the cuff 11, secured around the vein with suture seam 12, a subcutaneous injection port 13 with a resealable membrane 14, and a short conduit 15 providing for fluid communication between the injection port and the cuff (the injection port and resealable membrane may also be formed integrally with the cuff). The cuff may also be installed over the femoral artery 3L, proximal to the fistula, as shown in FIG. 3. Inflation of the cuff results squeezing the blood vessel within the cuff, essentially throttling flow through the blood vessel. The degree to which flow is mediated or throttled depends on the degree to which the cuff is inflated.

[0019] FIGS. 4, 5 and 6 illustrate use of bladder which merely impinges on the femoral vein to control bypass flow. As shown in FIG. 4, a bladder is placed in immediate contact with the femoral vein 9. The fistula 7 is shown in phantom, and may be fitted with a shunt or rivet 8. The bladder 16 is an elongate bladder, which may be conformal or non-conformal, which is inflated through the associated access port 17. FIG. 5 shows a cross section of the leg, with the bladder uninflated, impinging on the femoral vein, while FIG. 6 illustrates the effect of the inflated bladder on the femoral vein. Upon inflation, the bladder further impinges upon the femoral vein to impede flow, and thereby impede bypass flow from the femoral artery to the femoral vein.

[0020] FIGS. 7 and 8 illustrate a bladder assembly which assists in operably coupling the bladder to the blood vessel, so that distention of the bladder is certain to result in impingement on the blood vessel. In FIG. 7, the bladder 16 is coupled to a band 21 which provides an anvil against which the balloon pushes the blood vessel, and prevents the blood vessel from merely moving in response to balder inflation. The band may be attached to the balloon at each end, as shown, or the band may be wrapped completely around both the bladder and the blood vessel. FIG. 8 illustrates another a bladder assembly which assists in operably coupling the bladder 16 to the blood vessel, so that distention of the bladder is certain to result in impingement on the blood vessel. In this figure, a relatively hard and rigid clip 22 is hinged or otherwise rotatably attached to the balloon at hinge point 23, on one end or the other, and is fastened with the hook or other closure mechanism 24 at the other, so that the bladder may be fastened to the blood vessel. The clip is narrow and elongate, so that it may be used as shown in FIG. 9, with the bladder 16 disposed in impinging relationship with the anatomical fistula 25 and the clip disposed on the opposite side of the fistula and closed upon the bladder or an extending structure (in this case, the conduit used to till the bladder). If a graft of significant length is used, the devices of FIGS. 7, 8 and 9 may be placed over contiguous parallel segments of the shunt and artery, or the shunt and the vein.

[0021] Any other adjustable vascular impingement device may be used, including the Flow-watch, pulmonary artery band system which includes a jack screw adjusted by a motor which is powered and controlled telemetrically, as described in Stergiopulis, Flow Control Device and Method, PCT App. PCT/EP00/06907 (Jan. 25, 2001), or screw operated bands such as those disclosed in Schlensak, et al., Pulmonary Artery Banding With A Novel Percutaneously, Bidirectionally Adjustable Device, 12 Eur. J. of Cardio-thoracic Surg. 931-933 (1997).

[0022] The devices and methods described above may be used to treat COPD as follows. First, a surgeon creates a fistula between an artery and a nearby vein. Preferably, the artery and vein are large, such as the femoral artery and the femoral artery. The fistula may he maintained, after artificial creation, either naturally to create an anatomical fistula comprising portions of the contiguous artery and vein healed together, or it may be a mechanically maintained fistula which is supported with a shunt or stent, or it may comprise a distinct shunt from the artery to the vein. After creating and stabilizing the fistula (ensuring that endoprosthesis are securely implanted, or that the anatomical fistula is structurally sound), the surgeon implants the flow restricting device (which may be any one of the devices described or mentioned herein) around the vein downstream from the fistula, or around the artery upstream from the fistula, or across the fistula itself. To control flow through the fistula, the cuff is inflated or deflated as necessary to achieve a desired bypass flaw volume. The desired by-pass flow volume is determined by monitoring blood oxygenation and cardiac function intra-operatively (that is, immediately after creation of the fistula and implantation of the flow restricting device) and/or (that is, before discharge) and adjusting bypass flow to obtain a medically indicated short-term change in such parameters. The desired by-pass flow should also he determined and adjusted post-operatively, after a stabilization period (a few weeks after surgery). The shunt will increase mixed venous oxygenation, (SvO.sub.2), increase the percentage of oxygen bound to hemoglobin (SpO.sub.2), increase the amount of oxygen dissolved in blood plasma (PaO.sub.2), and increase cardiac output and stroke volume (after remodeling). Initially (immediately after opening the shunt) the heart rate increases to provide increased cardiac output. Then, as the heart remodels the stroke volume increases and the heart rate comes back down to normal levels to maintain increased cardiac output. Lower bypass flow in the post-operative and stabilization time period may be desirable to avoid over stressing the heart and allow a more gradual cardiac re-modeling. Thus, the overall procedure may be accomplished by adjusting flow in the peri-operative and stabilization time frame to levels sufficient to increase PaO.sub.2 and/or SvO.sub.2 about 5% or more, and increase cardiac output by about 10% or more, followed by re-evaluation of the patient after stabilization and readjustment of by-pass flow to provide for an increase PaO.sub.2and/or SvO.sub.2 (relative to pre-operative levels) of about 10% to 20% or more, depending on patient tolerance. Should the heart rate increase attendant to the bypass flow be more tolerable, the bypass flow in the peri-operative and stabilization time frame may adjusted to higher levels, to provide for an increase in PaO.sub.2 and/or SvO.sub.2 of about 20% to 25% (for a COPD with low PaO.sub.2 and/or SvO.sub.2), followed by re-evaluation of the patient after stabilization (after long-term remodeling of the heart, the heart may be remodeled in response to the therapy) and reduction of by-pass flow to provide for an increase PaO.sub.2 and/or SvO.sub.2 (relative to pre-operative levels) by about 10% to 20%. The optimal levels of these parameters, and the optimum trade-off between increased blood levels, cardiac output and increased heart rate are expected to be refined with clinical experience.

[0023] Rather than impinging on the blood vessel as described above, the desired flow control may be achieved by providing, a shunt with a variable lumen cross-section or other flow control means which may act as a throttle valve. FIGS. 10 and 11 illustrate use of shunt with an integral bladder which may be inflated to control flow through the shunt, as desired to effect the arterial bypass flow as treatment for COPD. A shunt 26 is installed between the femoral artery and the femoral vein. The shunt additionally comprises a bladder 27 installed within the lumen of the shunt, which is filled as desired through the inflation port 28. As illustrated in FIG. 11, in which the bladder is partially inflated, the bladder partially occludes the shunt, to a degree dependent on the degree to which the bladder is inflated. The bladder may be fully inflated to fully occlude the shunt and prevent bypass flow. The shunt may be made of any suitable shunt material.

[0024] FIGS. 12 and 13 illustrate another mechanism for regulating fistula bypass flow, in which a membranous wall of the shunt may be magnetically drawn to control the size of the shunt lumen. In this embodiment, the shunt is provided with an rigid outer wall 29 and flexible inner wall 30. The dissectible portion of the inner wall which cuts across the lumen may be elastic or merely loose, so that it may be pulled against the outer wall to fully open the lumen. A magnet (or ferromagnetic mass) 31 is fixed to the dissectible portion of the inner wall, such that the magnet, and thus the dissectible portion of the inner wall, may be drawn against the outer by magnetic attraction to an extracorporeal magnet 32. The extracorporeal magnet may he an electromagnet with operating circuitry which is fixed to the patient in proximity to the shunt, or it may be a permanent magnet, the power of which may be selected to effect a desired degree of openness.

[0025] While the devices and methods have been described relative to the femoral artery and femoral vein, they may also be employed in other suitable contiguous or associated artery/vein pairs, including the aorta and inferior vena cava, the femoral vein and the iliopopliteal vein or iliac vein, the popliteal artery and popliteal vein, the carotid artery and the jugular vein, the brachial artery and brachial vein, the brachial artery and brachial vein, and the brachio-cephallic artery and subclavian vein. The artery-to-vein shunt may also be provided between remote anastomosis cites, such as the iliac artery to the inferior vena cava. Also, though discussed in terms of COPD treatment, the method should be useful to treat hypertension (pulmonary hypertension and arterial hypertension), left ventricular hypertrophy, and chronic hypoxia. Thus, while the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.