WO2002092150A2

WO2002092150A2 - Bio-mechanical device for supporting revascularization

Info

Publication number: WO2002092150A2
Application number: PCT/IB2002/003389
Authority: WO
Inventors: Eva Hubertova
Original assignee: Eva Hubertova
Priority date: 2001-05-14
Filing date: 2002-05-13
Publication date: 2002-11-21
Also published as: WO2002092150A3; AU2002321762A1; ITTO20010448A1

Abstract

A bio-mechanical revascularization support device is described comprising: means for accelerating blood flow (5); at least one prosthetic blood inflow conduit (1), connected at one end to an inflow artery (15), through which the blood penetrates into the inflow conduit (1), and at the other end to the means for accelerating blood flow (5); and at least one prosthetic blood outflow conduit (3), connected at one end to the means for accelerating blood flow (5) and at the other end, by means of end connectors (18), to at least one outflow artery (20) into which the accelerated blood penetrates.

Description

Bio-mechanical device for supporting revascularization

DESCRIPTION

The present invention concerns a biomechanical revascularization support device which specifically relates to revascularization of the lower limbs in humans. In vascular surgery, stenosis and occlusion in the femoropopliteal axis and of the leg vessels can currently be aided by surgical revascularization performed by means of implanting a vascular bypass graft made of prosthetic material (Goretex®, Dacron®), or the patient's own autologous saphenous veins in situ or reversed, with the aim of restoring proper blood flow below occluded areas, ensuring the vitality of the ischemic limb.

Such bypass grafts are usually performed in patients with disabling claudication or critical limb-threatening (amputation) ischemia, once collateral circulation has been depleted and medical therapy is no longer able to reverse the progression of the pathology and patient's symptoms. A bypass graft is performed using the donor artery axis, which is usually, in the lower limbs, the common femoral artery pre-bifurcation and the recipient artery axis, which can be the above/below-knee popliteal artery (performing an above/below-knee femoropopliteal bypass graft), or the tibial or interosseous arteries in different areas of the leg (performing a femorotibial interosseous artery bypass), which can extend to the malleolus.

The short and long term graft patency, particularly below-knee graft patency, is influenced by the presence of an adequate (vascular) recipient bed, which can be quantified preoperatively either angiographically or surgically through direct monitoring of the run-off quality - poor run-off can generally be a negative indicator in terms of the bypass patency.

In especially serious conditions, as often observed in diabetics or subjects with serious arteriosclerotic impairment, the lower limb arteries, often at thigh level, are so compromised that they perform arteriographic situation of the markedly ischemic areas, where collaterals are lacking and arteries capable of accepting a bypass are almost never present. Such patients who are not suitable candidates for surgical revascularization, currently conclude their course of treatment with hip or thigh-level amputation of the lower limb.

Even in patients with an adequate recipient bed but with a small-caliber recipient artery and a high flow resistance, the pressure thrust of the grafts, deriving from the existing pressure in the femoral artery above, optionally when long conduits are used below the knee or in the ankle, does not allow the flow obstacles to be overcome, which results in premature thrombosis of the graft, making the surgical approach futile. In surgery, therefore, a mechanism capable of increasing flow and pressure in grafts and in native arteries does not exist yet.

The aim of the present invention is to resolve the aforementioned technical problems by providing a biomechanical revascularization support device capable of recreating an adequate vascular bed in markedly ischemic areas via flow and pressure increase systems, and enhancing the quality of the existing vascular bed in order to ensure, afterwards, the technical success of the graft, finally, making technically possible a bypass in the aforementioned ischemic areas of the limbs, which are not currently suitable for revascularization or with several risk of failure. Increased pressure and perfusion could also be applied to peripheral trophic lesion cases, which require long healing time (for example diabetic foot), and also to cases in which a bypass is not necessary due to adequate distal flow.

Such a device, inserted into prosthetic thigh or leg grafts by using traditional surgical techniques, can be operated continuously or periodically in hospitalized patients via external motors under constant medical monitoring until the conditions (collateral circulation) necessary to perform a permanent bypass graft (for example a vein graft) are met.

An additional aim of the present invention is to provide a device similar to the aforementioned device, capable of increasing the blood flow and supplying blood at high pressure where needed, but configured and dimensioned so as to enable it to be implanted directly into a patient's thigh, powered by means of standard small batteries, from the inside of the body and controlled from outside by means of standard equipment, with periodic replacement (after several years) of the batteries and possible replacement of the device in the event of damage. The aforementioned and other aims and benefits of the invention, as will appear from the description below, are accomplished via a biomechanical revascularization support device such as the one described in claim 1. Preferred embodiments and non-obvious variants of the present invention constitute the scope of the dependent claims. Several preferred embodiments of the present invention, provided as a non-limiting example, will better illustrate the invention, with references to attached drawings in which:

- Figure 1 is a schematic view of a preferred embodiment of the device according to the invention, and

- Figure 2 is a schematic view of variant of the device in Fig. 1

- Figure 3 is a schematic view of a part of a device according to a different embodiment of the invention.

With reference to Fig. 1 , a preferred embodiment of the biomechanical revascularization support device according to the present invention is provided purely by way of non-limiting example. Said device substantially comprises:

- Means for accelerating blood flow 5;

- At least one prosthetic blood inflow conduit 1 , which is connected at one end to an inflow artery 15, through which the blood penetrates into the prosthetic blood inflow conduit 1 , and to the means for accelerating blood flow 5 at the other end to enable the blood to flow into said the means for accelerating blood flow 5, and

- At least one prosthetic blood outflow conduit 3, which is connected at one end to the means for accelerating blood flow 5 to enable blood outflow at an increased velocity from the means for accelerating blood flow 5 themselves, and is connected at the other end to at least one outflow artery 20, into which the accelerated blood penetrates, by means of end connectors 18. The main application, in vascular medicine of the device according to the invention is the connection of the femoral artery (as the inflow artery 15) of a human leg 2 to the popliteal artery (as the outflow artery 20), which is connected to the leg vessels (not shown in the figures) located in the part of the leg 2 below the knee. The other main application of the device according to the invention is the connection of the popliteal artery (as the inflow artery 15) to the leg vessels (as the outflow artery 20) located in the part of the leg 2 below the knee.

In particular, in order to allow the flow of the accelerated blood at a pressure which is slightly lower than that of the blood coming from the femoral artery, the means for accelerating blood flow 5 can comprise a paddle wheel rotor 7 connected to a drive motor 11 by means of a drive shaft 9: the drive motor 11 is placed outside of the patient's lower limb at leg or thigh-level, while the paddle wheel rotor 7 and the drive shaft 9 are surgically inserted into the patient's thigh 16 and leg 2, allowing the drive shaft 9 to protrude outside from it. This way, it is possible to periodically connect the hospitalized patient to the motor 11 and activate the rotor 7 to supply blood to the popliteal artery or leg vessels needing it. Through arteriographical monitoring, it is possible to assess whether the device has actually restored an adequate collateral circulation by recruiting capillary potential through increased blood flow and increased perfusion pressure. As an alternative, equivalent to the above-described implementation, the paddle wheel rotor 7 could be replaced by a pump (not shown) with the same blood flow accelerating functions. Also in this case, the pump could be connected to a drive motor (such as 11 in Fig. 1 ) by means of a drive shaft (such as 9 in Fig. 1 ) and again the drive motor 11 could be placed outside the patient's lower limb at leg or thigh- level. In the previous cases (or in other similar cases wherein the means for accelerating flow 5 are equivalent accelerating/pressurizing) the drive motor 11 is preferably equipped with a means for displaying 13 and means be monitoring and controlling (for example of the keyboard or remote control type) in order to display, monitor and regulate the flow and pressure of the blood sent to the device; that is obviously useful during hospitalization of the patient, when continuos and effective monitoring is necessary.

The device according to the invention, being versatile, could also be designed to be implanted into the patient's lower limb at thigh 16 or leg 2 level for continuative use outside the hospital. Also in this case, the device would necessitate external activation and control equipment, of the type used in cardiac pacemakers.

In order to implement this alternative configuration, the means for accelerating blood flow 5 of the device according to the invention, are implemented as a single compact unit 25 (represented schematically in Fig. 2), inside of which are positioned (obviously with a small dimension) for example a paddle wheel rotor (similar to the rotar 7 in Fig. 1 ) connected to a drive motor (not shown) and a battery (not shown), for example a battery with a life of several years.

Again, the paddle wheel rotor may be replaced with a pump or an equivalent accelerating and pressurizing component, without modifying the rest of the configuration of the device. Finally, in order to optimize the connection of the device to the popliteal artery and the leg vessels, the end connectors 18 are preferably common cannulas or small prosthetic conduits, small enough to allow their implantation into the arteries themselves. According to an alternative embodiment, schematically represented in figure 3, said means for accelerating blood flow 5 may comprise a piston pump. Non return valves

31 and 33 are preferably connected to the prosthetic blood inflow 1 and outflow 3 conduit, to allow only blood inflow (valve 31) and outflow (valve 33) and not reverse circulation. The prosthetic inflow 1 and outflow 3 conduits are connected to a chamber 32, whose volume expands or shrinks due to the alternative motion of the piston 30. According to a preferred embodiment, the chamber 32 connected with said prosthetic conduits and able to expand and shrink, comprises at least a deformable wall (of suitable material, flexible and having adequate resistance, preferably bio- compatible, such as, for example, Dacron®), that the piston 30 compresses or releases, alternatively moving according to arrow D. The wall 34 may be suitably designed, for example with a cylinder shape. It will be suitably connected to the casing 36 of said means 5, to delimit the chamber 32. The expansion of the chamber

32 may be due to blood pressure itself, when the piston does not compress it. Alternatively, suitable means may be provided to make said chamber expand. For example, when the wall 34 is cylindrically shaped, its upper surface 40 may be connected to the piston 30, which will be able to drag it in its motion. Otherwise, spring or elastic means may be provided inside the chamber 32, said means acting on the wall 34. According to an alternative embodiment, the wall 34 can have no upper surface, and be connected by its upper edge to the perimeter of the piston 30, upwardly delimiting the chamber 32.

Alternatively, the chamber 32 may be directly delimited by the walls of the casing 36 and the piston 30 itself, which , in this case, should be liquid tight with the lateral walls 35 of the casing. Motion can be again provided by a drive motor, connected to the piston by a shaft 34, transmitting the alternative motion. The drive motor may be placed outside the patient, or be contained in a unit placed inside the patient's body, as previously discussed.

Several ways of implementing the invention have been described, but they may obviously be subjected to variations within the same innovative concept. For example, the device according to the present invention could be used to treat vascular disturbances in other parts of the human body or in animals. In addition, a larger number of prosthetic inflow or outflow conduits could be foreseen, or the device could be produced in a form adapted for direct application to standard vascular bypasses, already available on the market.

Claims

1. A biomechanical revascularization support device characterized by the fact that it includes: - Means for accelerating blood flow (5);

- At least one prosthetic blood inflow conduit (1), said prosthetic blood inflow conduit (1 ) being connectable at one end to an inflow artery (15), through which the blood penetrates into the prosthetic blood inflow conduit (1 ), and at the other, end to the means to increase blood flow velocity (5), to enable the blood to flow into said means for accelerating blood flow (5), and

- At least one prosthetic blood outflow conduit (3), being connectable at one end to the means for accelerating blood flow (5), to enable accelerating blood flow out, from said means for accelerating blood flow (5), and being connectable at its other end by means of end connectors (18), to at least one outflow artery (20), into which the accelerated blood penetrates.

2. The device according to claim 1 , characterized by the fact that said inflow artery (15) is the femoral artery of a human thigh (16) and said at least one outflow artery (20) are the popliteal artery and the leg vessels below the knee.

3. The device according to claim 1 , characterized by the fact that said inflow artery (15) is the popliteal artery of a human leg (2) and said at least one outflow artery (20) are the leg vessels in the part of the leg (2) located below the knee.

4. The device according to claim 2 or 3, characterized by the fact that said means for accelerating blood flow (5) are a paddle wheel rotor (7) connected to a drive motor (11 ) by means of a drive shaft (9), said drive motor (11) being placed outside of patient's limb at leg (2) or thigh (16) level.

5. The device according to claim 2 or 3, characterized by the fact that said means for accelerating blood flow (5) are a pump connected to a drive motor (11) by means of a drive shaft (9), said drive motor (11) being placed outside of a patient's limb at leg (2) or thigh (16) level.

6. The device according to claim 4 or 5, characterized by the fact that said drive motor (11) is equipped with a means for displaying (13) and means for monitoring and controlling to display, control and regulate the flow and pressure of the blood sent to the device.

7. The device according to claim 2 or 3, characterized by the fact that said means for accelerating blood flow (5) are a unit (25) composed of a paddle wheel rotor (7) connected to a battery and drive motor, said unit (25) being placed inside a patient's limb at thigh (16) or leg (2) level.

8. The device according to claim 2 or 3, characterized by the fact that said means for accelerating blood flow (5) are a unit (25) composed of a pump connected to a drive motor and a battery, said unit (25) being placed inside a patient's limb at thigh (16) or leg (2) level.

9. The device according to claim 1 , characterized by the fact that the end connectors (18) are cannula or small prosthetic conduits.