WO1999004833A1

WO1999004833A1 - Ventricular cardiac aid device with counter-pulsation

Info

Publication number: WO1999004833A1
Application number: PCT/FR1998/001631
Authority: WO
Inventors: Jean-Antoine Gruss; Pierre Serre-Combe; Alain Bouvier; Iraj Gandjbakhch; Daniel Guilmet; Pierre Squara
Original assignee: Commissariat A L'energie Atomique
Priority date: 1997-07-24
Filing date: 1998-07-23
Publication date: 1999-02-04
Also published as: FR2766373B1; FR2766373A1

Abstract

The invention concerns a ventricular cardiac aid device with counter-pulsation, comprising the following implanted elements: an aortic sleeve (1) placed on the ascending aorta (10) and capable of producing a counter-pulsation on the blood in the aorta by the effect of an intermediate fluid flowing into the sleeve; an electrohydraulic actuator (2) acting upon the intermediate fluid for producing said counter-pulsation; a compliance chamber (3) for accommodating the variation in volume of the intermediate fluid when the actuator (2) is operating; electric supply means for powering the electrohydraulic actuator (2).

Description

VENTRICULAR HEART ASSISTANCE DEVICE A

COUNTER-PULSATION

Technical area

The present invention relates to a heartbeat ventricular assist device. This device acts as a storage and generation system for pulsating hydraulic energy. It is designed to be used as a component of an autonomous cardiac assistance device operating in counter-pulsation.

State of the art

The heart assist devices currently used, such as the system NOVACOR ^® NP 100 of BAXTER company and IP ^® HeartMate TCI company uses a heart pump comprising an actuator and a flexible chamber or pocket. The flexible chamber periodically fills or empties of blood under the action of the actuator. This actuator is either an electromagnet or an electric motor with transformation, by means of a cam, of the circular movement provided by the electric motor into linear movement. The mechanical action is done on the pocket (in polyurethane) placed in diversion on the patient's left ventricle. Valves, allowing a unidirectional circulation of blood, are placed at the entry and exit of the bag.

These devices pose a number of problems. Their operation, in parallel with the native heart, leads to a non-synergistic functioning of the latter with the consequence, in most case, a degradation of the functions of the heart. The assistance device must therefore completely replace the left ventricle of the patient, which, associated with an average efficiency of the actuators, implies a high electrical power (of the order of 25). As a result, the electrical power required to ensure one day's autonomy must be supplied by relatively large batteries, which cannot be implanted in the human body. These batteries are external to the body. They are worn over the shoulder or on the belt, the electrical connection with the implanted device being made by a transcutaneous cable.

These devices also cause micro or macro-thromboembolisms which are due in particular to the large synthetic exchange surface and the hydraulic design inducing zones of turbulence or stasis. The actuators and valves induce significant noise, causing discomfort for the patient and those around him. The security of these devices is questionable. A tear in the pocket can lead to hemorrhage or gas embolism. Any failure can have fatal consequences in seconds because the native heart no longer works.

The installation of such a device requires total extracorporeal circulation as well as an incision of the apex of the heart for the placement of a cannula. These operations are always disabling for the native heart.

There are also known projects for devices using skeletal muscles such as the latissimus dorsi as an actuator. Muscle can be wrapped around the aorta

(aortomyoplasty) or heart (cardiomyoplasty). It can also indirectly activate a blood bag using a mechanical or hydraulic transformation. In this case, the muscle is actuated periodically using a stimulator-type device so as to exert a mechanical action on the cardiovascular system. These devices have a number of drawbacks. Their installation requires a heavy and disabling surgical operation for an already weakened patient. The physiological transformation of the muscle to make it suitable for rapid cyclical operation requires learning for several weeks, which means that the cardiac assistance device is not operational immediately after the operation. Two operations under general anesthesia are necessary to definitively set up the system. Ultimately, muscle fatigue problems may appear. Finally, the effectiveness of the system from the perspective of long-term mortality is controversial.

It has also been proposed, in particular in patent US-A-5 290 227, to place a centrifugal pump in series on the ascending aorta and operating in phase with the native heart. The functioning of the pump in this part of the aorta makes it possible to nourish well the brain and the upper body whose ramifications lead to the aortic arch. However, the installation of the centrifugal pump requires total extra-corporal circulation, always disabling. The left and right coronary arteries being located immediately at the outlet of the heart after the aortic valve, and therefore upstream of the assistance turbine, the systolic operation of the centrifugal pump causes a reduction in coronary pressure and therefore a left coronary deficit and above all right.

We also know of centrifugal pumps placed in diversion on the left ventricle. These devices potentially allow better reliability due to the absence of diaphragm or bag made of polymer material, the resistance of which over time, with repeated stresses, is always problematic. In addition, they also make it possible to overcome the delicate problem constituted by pressure compensation resulting from variations in the volume of the pockets. Nevertheless, serious problems remain concerning: the reliability of the bearings or bearings, problems of thrombus on the bearings, noise problems, the need for extra-corporal circulation for the installation of these devices. In addition, a failure of the pump can lead to closed circuit operation of the heart because there is no valve. In addition, there is a risk of coagulation in the branch in diversion.

There are also known cardiac assist devices operating in counter-pulsation. Intra-aortic balloon pumps (IABP) have been used clinically since the 1960s in recovery from heart shock. The balloon is inserted into the patient's aorta, usually through the femoral artery. An external console makes it possible to inflate and deflate the balloon, with helium, in synchronism with the heart. The balloon is inflated in diastole and deflated in systole. Deflating the balloon decreases the afterload of the heart, which therefore ejects more blood. The inflation of the balloon in diastole raises the aortic pressure and forces the blood in the arterial circuit. However, IABPs are not suitable for long-term assistance for at least two reasons. On the one hand, the balloon would not resist it from a mechanical point of view. On the other hand, operation requires a console and an external gas storage not very compatible with normal life. Of moreover, the percutaneous passage of pneumatic tubing constitutes an important source of infection.

One can also use aortomyoplasty to exert the action of counter-pulsation, by wrapping a skeletal muscle (generally the latissimus dorsi) around the aorta. This method has the drawbacks mentioned above with regard to the use of skeletal muscles. In addition, there is a risk of damage to the aortic wall due to repeated compressions of the aorta.

The article by A. KANTRO ITZ et al. entitled "A Mechanical Auxiliary Ventricle. Histologie Responses to Long-term, Intermittent Pumping in Calves", published in the journal Trans. Am. Soc. Artif. Intern. Organs, Vol. 41, pages M340-M345, 1995, describes a project experimented in animals. An extra-aortic balloon is activated according to the same principle as the IABP. This system always has the disadvantage of requiring a portable, but external, pneumatic energy source.

Other projects, using the principle of counter-pulsation, have been disclosed. They are described in documents WO 93/05827, EP-A-0 216 042, WO 92/08500 and US-A-4 979 936. In US-A-4 938 766, RK JARVIK describes devices implanted on the aorta and performing passive hydraulic storage with transfer of hydraulic energy between the systole phase and the diastole phase. The storage systems described are either mechanical (using a spring structure) or magnetic (using permanent magnets). These devices have apparently not been practically tested. In any case, the actual gain in cardiac output should be limited, as the devices provide no energy to the cardiac system. Statement of the invention

To overcome the drawbacks of the prior art mentioned above, according to the present invention, a cardiac assistance device is proposed using the following elements:

- an aortic prosthesis performing the counter-pulsation action on the aorta. This prosthesis is in the form of an aortic sleeve placed on the descending aorta and in which the blood circulates.

- an intermediate fluid external to the sleeve, ensuring the cyclic compression of the sleeve in the diastolic phase and providing the counter-pulsation effect. - an electro-hydraulic actuator transforming stored electrical energy into hydraulic energy delivered to the intermediate fluid.

- a compensation chamber, also called compliance chamber, making it possible to accommodate the variation in volume of intermediate liquid.

- an electrical energy storage device allowing complete energy autonomy of the cardiac assistance device.

- a system of energy and data transmission between the outside and the inside of the body allowing the recharging of the batteries and the remote control of the device.

The subject of the invention is therefore a heartbeat ventricular assist device, comprising the following implanted elements:

means capable of performing a counter-pulsation action on the blood circulating in the aorta under the effect of an intermediate fluid, - an electro-hydraulic actuator exerting its action on the intermediate fluid to perform said counter-pulsation action,

- electrical supply means for supplying the electro-hydraulic actuator, characterized in that:

the means capable of performing a counter-pulsation action consist of an aortic sleeve placed on the descending aorta and into which the intermediate fluid penetrates,

- The device further comprises a compliance chamber for accommodating the change in volume of the intermediate fluid during the operation of one actuator. According to a first alternative embodiment, the aortic sleeve is inserted on the descending aorta. In this case, the aortic sleeve may comprise a tubular membrane of flexible material, replacing a section of the aorta, the membrane being enclosed within a rigid shell sealed on the aorta so as to define a chamber. annular around the membrane, the intermediate fluid entering the annular chamber through an orifice provided in the shell.

According to a second alternative embodiment, the aortic sleeve is attached to the descending aorta. In this case, the aortic sleeve may comprise an element made of flexible material enclosing the aorta and constituting a closed volume with an orifice for the introduction of the intermediate fluid, the sleeve also comprising a rigid shell to contain said element made of flexible material.

The actuator can be a centrifugal pump. It can also use a ferrofluid as a driving element. The power supply means may include one or more rechargeable batteries.

Preferably, the device further comprises implanted means allowing the reception of an electromagnetic signal for recharging said battery.

It may also further include implanted means allowing data transmission by induction or by infrared radiation with an external device.

The compliance chamber may include means making it possible to introduce, while the compliance chamber is already implanted, gas for charging or discharging it.

Brief description of the drawings

The invention will be better understood and other advantages and features will appear on reading the description which follows, given by way of nonlimiting example, accompanied by the appended drawings among which:

FIG. 1 represents a heartbeat ventricular assist device according to the present invention and shown in position on a patient,

FIG. 2 represents an aortic sleeve according to the present invention, inserted on the descending aorta of the patient,

FIG. 3 represents an aortic sleeve according to the present invention, attached to the descending aorta of the patient,

FIG. 4 is a sectional view along the axis IV-IV of FIG. 3, - Figure 5 shows another aortic sleeve according to the present invention, attached to the descending aorta of the patient.

Detailed description of embodiments of the invention

The cardiac assistance device shown in FIG. 1 comprises an aortic sleeve 1 placed on the descending aorta 10 of the patient, an electro-hydraulic actuator 2, a compliance chamber 3 and an electrical circuit 4 comprising one or more batteries of food. The electro-hydraulic actuator 2 is in fluid communication with the aortic sleeve 1 through the flexible conduit 5. It is also in fluid communication with the compliance chamber 3 through the flexible conduit 6. The electric circuit 4 supplies the actuator electro-hydraulic 2 thanks to the electrical cord 7. All these elements are of course made of biocompatible materials.

The aortic sleeve 1 is described in more detail in Figure 2 which is a partial view. In section to show the inside of the sleeve. As shown in Figure 2, this aortic sleeve replaces a section of the aorta. It comprises a membrane 11 located between two tubular ends 12 and 13 intended to be grafted onto corresponding parts of the aorta. The membrane 11 is made of flexible material. The aortic sleeve 1 also comprises a rigid shell 14, of generally cylindrical shape, sealingly sealed on the tubular ends 12 and 13. Between the rigid shell 14 and the assembly constituted by the membrane 11 and the tubular ends 12 and 13 exists so a space elongated annular 15. The flexible conduit 5 (see FIG. 1) terminates in this annular space 15.

The aortic sleeve performs the counter-pulsation action on the blood under the effect of the intermediate fluid introduced into the annular space 15 thanks to the flexible conduit 5. In FIG. 2, the membrane 11 has been shown in solid lines during the systolic phase, that is to say while the intermediate fluid flows back towards the actuator. The membrane is shown in dashed lines during the diastolic phase, that is to say while the intermediate fluid flows towards the annular space 15.

This type of sleeve (prosthetic sleeve) must have a lower compliance than that of the natural aorta so as to decrease the afterload of the heart and increase its ejection, therefore its flow. However, compliance must not be zero either. It can typically be of the order of 1 to 3.10 ⁸ Pa.m ³ . Compliance can be achieved at the source, that is to say at the level of the prosthetic sleeve, by giving a certain elasticity to the latter. This can be achieved for example using metallic reinforcements overmolded in the wall of the membrane 11 and forming a spring, such as the reinforcements 16. The compliance can also be transferred further in the actuation chain, after the intermediate fluid , and integrated at the level of the electro-hydraulic actuator.

Another example of an aortic sleeve is described in Figure 3 in a perspective view. Unlike the aortic sleeve described above, this sleeve is attached to the descending part of the aorta 9 and not inserted into the aorta. The sleeve 20, shown in Figure 3, comprises an element 21 of flexible material here taking the form of a sheath when it is wound around the aorta 10. This flexible element constitutes a closed volume in which the flexible conduit 5 terminates. A rigid shell 22 encloses the element 21 so that this element can act directly on the aorta as a function of the pressure exerted by the intermediate fluid. As shown in Figure 4, the rigid shell 22 has a hinge 23 and a clasp 24 facilitating its implementation.

Another example of an added aortic sleeve is shown in partially sectional view in FIG. 5. In this example, the element 31 made of flexible material takes the form of a serpentine when it is wound around the aorta 10. This flexible element constitutes a closed volume in which the flexible conduit 5 terminates. A rigid shell 32, similar to the shell 22 of FIGS. 3 and 4, encloses the element 31 so that the action of the intermediate fluid is exerted directly on the 'aorta.

The inserted and attached aortic sleeves do not have the same properties and their use will be depending on the implantation conditions. Compared to an inserted sleeve, an added sleeve makes it possible to obtain excellent hemo-compatibility since there is no synthetic material in contact with the blood. Its implantation is simplified since it is possible to install it, and possibly remove it without damaging the aorta and the intercostal arteries. In addition, no interruption of blood flow is necessary during the procedure. On the other hand, we only raise the diastolic pressure without increasing overall arterial compliance, which is less favorable at the synergistic level for the heart and limits the increase in blood flow. Finally, there is, at the long, a risk of compressing damage to the aortic wall.

The intermediate fluid provides compression towards the inside of the aortic sleeve and therefore of the arterial circuit.

The volume of the arterial circuit is reduced in the diastolic phase, and increased in the systolic phase, thus ensuring the increase in blood flow by physiological effect on the heart. This intermediate fluid is preferably physiological saline, or a blood substitute, such as DEXTRAN, so as not to create a problem in the event of leakage of this fluid inside the body or in the arterial circuit. The electro-hydraulic actuator 2 makes it possible to supply hydraulic energy to the aortic sleeve using the intermediate fluid. The actuator can advantageously use ferrofluids as the driving element. This actuator can also be constituted by a centrifugal pump.

The compliance chamber 3 (or compensation chamber), represented in FIG. 1, makes it possible to compensate for the variations in volume of the intermediate fluid. It is filled with a gas such as air, argon, nitrogen, SF ₆ . Variations in the volume of the intermediate fluid in the actuator cause, depending on the type of electro-hydraulic actuator, variations in the volume of gas present in the actuator. The compliance chamber makes it possible to accommodate these variations in volume in the human body, without physical communication with the outside.

Access to the interior of the compliance chamber may be provided by means of a flexible tube 8, for example made of silicone polymer, connecting the interior of the compliance chamber has a chamber 9, for example made of polyoxymethylene, provided with a septum, for example made of silicone. We can then load or reload gas, transcutaneously, the compliance chamber.

The ventricular cardiac assistance device according to the invention is completely autonomous thanks to one or more rechargeable batteries implanted in the body. The battery or batteries are housed in the electrical circuit 4.

An autonomy of 24 hours minimum can be ensured thanks, on the one hand to the very principle of the counter-pulsation device which works in synergy with the heart, and requires little energy, on the other hand thanks to a good efficiency of the actuator coupled to high-performance batteries. Typically, an electrical energy of the order of 2 W is necessary for the operation of the device. Given the yields, a 24-hour autonomy requires Cd-Ni batteries weighing approximately 1.2 kg (mass energy 40 Wh / kg) or lithium-ion batteries weighing approximately 0 , 8 kg (mass energy 60 Wh / kg), which is compatible with complete implantation.

The device can also be provided with a remote power supply and remote control system. This system ensures the recharging of the batteries implanted preferentially during the patient's rest periods, as well as the data transmission and the remote control of the device. The techniques of data transmission by induction or infrared are well known and have been successfully tested in animals. Such a system is shown in Figure 1. It includes an organ 40 located just under the skin of the patient and performing two roles vis-à-vis an external device 41. The organ 40, connected to the circuit electric 4 by the electric cord 42, can be receiver of an electromagnetic wave making it possible to charge by induction the batteries housed in the electric circuit 4. It can be transmitter of data provided in the form of electric signals by a device housed in the electric circuit 4 and transmitting information on the state of the cardiac assist device and on the state of the patient.

The present invention provides the following advantages. The use of an intermediate fluid makes it possible to decouple the aortic sleeve from the actuator, therefore to better distribute the implanted volumes, and not to overstress the aorta mechanically. It provides high reliability because there are no moving mechanical parts, so no risk of wear, seizure, etc. The implantation does not require total extra-corporeal circulation, nor an incision in the apex, operations always disabling for the native heart. The device is intrinsically safe, a failure of the device causing no risk of blood clotting and thromboembolism, nor any reduction in blood flow ensured by the natural heart. Any tearing of the aortic sleeve by fatigue would not have any unfortunate consequences, since the fluid external to the sleeve is hemocompatible and ensures a double sealing barrier. In addition, since pressure compensation is done internally, the risks of infectious complications due to the passage of a percutaneous tube are eliminated. The design of the device in counter-pulsation allows operation in synergy with the heart, which is not the case with most current assistance devices that operate in complete bypass of the ventricle. We can hope for more cases of recovery of functions of the native heart, because the heart works in better conditions, and the device promotes coronary perfusion. Under these conditions, the device is designed to be easily removed. Operating noise is lower than for current devices, leading to a better quality of life for the patient and those around him. The patient benefits from a better quality of life due to a complete implantation of the cardiac assistance device, in particular he no longer needs bags or an external belt to house the supply batteries.

Claims

1. Counter-pulsating ventricular cardiac assistance device, comprising the following implanted elements: - means capable of performing a counter-pulsing action on the blood circulating in the aorta under the effect of an intermediate fluid,

- an electro-hydraulic actuator (2) exerting its action on the intermediate fluid to perform said counter-pulsation action,

- electrical supply means for supplying the electro-hydraulic actuator (2), characterized in that:

- The means capable of performing a counter-pulsation action consist of an aortic sleeve

(1, 20, 30) placed on the descending aorta (10) and into which the intermediate fluid penetrates,

- The device further comprises a compliance chamber (3) for accommodating the change in volume of the intermediate fluid during the operation of the actuator (2).

2. Device according to claim 1, characterized in that the aortic sleeve (1) is inserted on the descending aorta (10).

3. Device according to claim 2, characterized in that the aortic sleeve (1) comprises a tubular membrane (11) made of flexible material, replacing a section of the aorta, the membrane being enclosed inside a rigid shell (14) sealed on the aorta so as to define an annular chamber (15) around the membrane (11), the intermediate fluid penetrating into the annular chamber through an orifice provided in the shell (14).

4. Device according to claim 1, characterized in that the aortic sleeve (20.30) is attached to the descending aorta (10).

5. Device according to claim 4, characterized in that the aortic sleeve (20.30) comprises an element of flexible material (21.31) enclosing the aorta and constituting a closed volume with an orifice for the introduction of the intermediate fluid , the sleeve also comprising a rigid shell (22,32) to contain said element made of flexible material.

6. Device according to any one of claims 1 to 5, characterized in that the actuator (2) is a centrifugal pump.

7. Device according to any one of claims 1 to 5, characterized in that the actuator (2) uses a ferrofluid as a driving element.

8. Device according to any one of claims 1 to 7, characterized in that the electrical supply means comprise at least one rechargeable battery.

9. Device according to claim 8, characterized in that it further comprises implanted means (40) allowing the reception of an electromagnetic signal for recharging said battery.

10. Device according to any one of claims 1 to 9, characterized in that it further comprises implanted means (40) allowing data transmission by induction or by infrared radiation with an external device (41).

11. Device according to any one of claims 1 to 10, characterized in that the compliance chamber comprises means (8,9) making it possible to introduce, while the compliance chamber is already implanted, gas for charging it or recharge it.

12. Device according to claim 3, characterized in that said membrane (11) is provided with flexible reinforcements (16).

13. Device according to claim 5, characterized in that the element made of flexible material (31) of the aortic sleeve is capable of being wound around the aorta (10) in the manner of a serpentine.

14. Device according to claim 5, characterized in that the element made of flexible material (21) of the aortic sleeve is capable of being wound around the aorta (10) in the manner of a sheath.

15. Device according to any one of claims 5, 13 and 14, characterized in that the rigid shell (22,32) comprises a hinge (23) and a closure means (24) allowing it to be arranged around the element made of flexible material (21,31) to contain it.