Device for assisting or supplementing the heart.

Abstract

The invention relates to a device for temporary circulatory assistance or replacement of a patient's heart, the reservoir (11) having a pear shape with a base of large diameter d1 reducing in its height to end at a top of small diameter d2 such that d1 is at least equal to seven times d2, i.e. d1 > 7d2, and a deformable membrane (70) is fixed under the base (60) of the reservoir (11), said membrane (70) having an upper surface movable under the action of an actuating means so as to increase or reduce the internal volume of the reservoir (11), the membrane (70) forming one of the surfaces of the reservoir (11) with variable internal volume, said upper surface extending, in an initial state, along the plane of the base (60) of the reservoir (11). Figure to be published with the abstract: Fig. 2

Description

Title of the invention: Device for assisting or replacing the heart. Technical field.

[0001] The present invention relates to a device for assisting or supplementing the heart and advantageously the lungs (oxygenator).

[0002] The invention thus also relates to a device for assisting or replacing the heart comprising or using such an admission and ejection cannula. The term assistance is used when a portion of the blood arriving at the heart is removed while the term replacement is used when all, or almost all (> 90%), of the blood arriving at the heart is removed by the heart replacement device.

[0003] It concerns the technical field of devices used for extracorporeal circulatory assistance / supplementation which maintain hemodynamics compatible with life, in the context of a failure of the cardiac muscle threatening the patient's life prognosis, following acute or chronic heart failure (coronary insufficiency and / or cardiovascular disease, or other associated pathology). State of the art.

[0004] Severe heart failure, or the inability of a person's heart to produce enough blood to meet the body's needs, causes a very poor quality of life, very high medical treatment costs, and mortality for hundreds of thousands of patients each year. Many pharmacological, biological, and implanted device interventions have been developed to treat this condition (failure), many of which are patented, but despite these efforts, heart failure remains a major public health problem.

[0005] The cardiovascular system is a closed, pressurized hydraulic circuit, internally lined by endothelial cells. The endothelium (four kilos for seventy kilos) is continually subjected to the tangential forces of shear stress which are essential for maintaining endothelial function including vascular tone through nitric oxide synthesis (NOS), blood coagulation, the inflammatory response, atherosclerosis, angiogenesis and apoptosis.

[0006] Extracorporeal circulation (ECC) is a medical device used as a replacement for the heart and lungs in operating rooms, cardiac catheterization laboratories or intensive care units, for pediatric or adult patients.

[0007] As a source of energy, a CEC console or central unit comprises a mathematical model designed from physical laws governing the movement of a fluid in a closed circuit.

[0008] This circuit is concretely composed of a pump, a heat exchanger, a flow meter, a blood gas and electrolyte analyzer, a pressure recorder as well as biocompatible material such as tubing, arterial and venous cannulas, venous reservoir, oxygenator, arterial filter. Usually a centrifugal or peristaltic pump is used as an arterial head pump and four other peristaltic pumps are used for cardiotomy suction, cardiac chamber circulation, cardioplegia administration and a backup pump.

[0009] CEP is necessary to maintain organ perfusion and metabolic functions, oxygen transport during surgical cardioplegia or to assist the heart muscle during surgery. If failure persists, ECMO ("Extracorporeal Membrane Oxygenation") or ECLS ("Extracorporeal Life Support") is indicated. These systems are simpler than standard CEP and are transportable, with a usage time of several days, unlike conventional CEP. Indeed, unlike conventional CEP, both ECMO and ECLS are maintained until the patient's cardiopulmonary recovery or as a relay before transplantation.

[0010] The heart's function is to distribute blood throughout the body to transport the oxygen and nutrients necessary for the functioning of the various organs. It is divided into two parts: the right heart, which receives venous blood (depleted in oxygen) through the vena cavae and sends it through the pulmonary artery to the respiratory system (where it is replenished with oxygen), and the left heart, which receives oxygenated blood through the pulmonary veins to eject it through the aorta to the various organs.

[0011] Contractions of the heart muscle (pump) allow blood flow to be generated in the body. They allow continuous control of blood flow to the physiological needs of the body and each organ (for example, they increase in heart rate and flow with physical effort).

[0012] The coronary arteries continuously irrigate the heart muscle and ensure its oxygenation and energy supply, enabling its pumping function.

[0013] When these arteries narrow (induced by risk factors such as hypercholesterolemia, hypertension, smoking, diabetes, heredity and others), the heart muscle is no longer sufficiently irrigated and therefore oxygenated and it can become necrotic. The major consequence of this coronary insufficiency is mainly characterized by the inability of the heart muscle to generate a blood flow adapted to the vital needs of the body (ischemic heart failure).

[0014] In the presence of a failure of the cardiac muscle (in the case of a myocardial infarction for example), it is necessary to temporarily supplement the pumping function of said cardiac muscle with a mechanical circulatory assistance system.

[0015] Among the circulatory assistance systems currently in use, extracorporeal circulation devices are known which make it possible to bypass the failing heart by using a controlled pump placed outside the body, which receives blood at the level of the vena cava and injects it at the level of the (thoracic) aorta, to mechanically generate a continuous blood flow compatible with the vital needs of the organism.

[0016] Although these systems have demonstrated their effectiveness in their conventional circulatory support functions, they are not satisfactory:

[0017] - there is no modularity possible depending on the pathology treated, only a right heart / left heart placement is offered;

[0018] - the integration of external oxygenation may be obligatory;

[0019] - the components of these assistance systems are sterile, pre-assembled and pre-conditioned. Due to this type of assembly, the possible modularity of the patient and / or pathology remains limited;

[0020] - the installation of these devices is complex. It requires intervention heavy surgery, in an operating room, surrounded by specialized human resources that are only found in large hospital centers and which have an advanced technical platform;

[0021] - the floor space is very large;

[0022] - the purchase price is very high;

[0023] - the possibility of mechanical stress on the formed elements of the blood (for example red blood cells) suggests a significant risk of hemolysis; - the control of the generated blood flow does not take into account the patient's physiology;

[0024] - finally, it is extremely important to be able to suck up and eject the exact quantity of blood needed, and at the precise moment when this quantity aspirated or injected is desired for the benefit of the patient.

[0025] The present application intends firstly to propose a solution to this latter problem, which current CECs cannot achieve effectively, it being understood that the blood flow rate in such CECs is significant, even very significant, at least 2 to 3 or even 5 liters per minute. In other words, the device according to the invention has the primary aim of enabling better performance and increased pumping precision in the case of circulatory assistance.

[0026] Document FR 2872707 can be considered to constitute the state of the art that the present invention seeks to improve.

[0027] The invention aims to remedy this state of affairs.

[0028] It also aims to allow a modular installation depending on the failure of the blood flow generating function, an oxygenation system not necessarily being integrated into the device which is the subject of the invention.

[0029] The invention also aims to allow the use of the device which is the subject of the invention without the need for major surgical intervention and in an operating theatre. In this way, the device which is the subject of the invention can be used both in an operating theatre and in a coronary and / or vascular angioplasty room or an intensive care and / or resuscitation unit.

[0030] The invention also aims to facilitate the adaptation of the system which is the subject of the invention to the different types of pathologies encountered and to the clinical situation of the patient in order to maintain hemodynamics compatible with the life of said patient.

[0031] The invention also aims to minimize mechanical stresses on the blood-forming elements.

[0032] Another essential objective is to propose a more efficient technical solution.

[0033] A complementary objective is to propose a simpler and easier to manage technical solution for the operator(s).

[0034] The invention also aims to propose a circulatory assistance device of simple design, mobile, easy to implement and use, thus contributing to a significant reduction in the associated costs.

[0035] The invention also aims to propose a circulatory assistance device of simple design, mobile, easy to implement and use, thus contributing to a significant reduction in the associated costs. Presentation of the invention.

[0036] It has thus been noted by the applicant, after various experiments and manipulations, that it is particularly interesting to propose a reservoir of specific shape as well as a membrane, forming a wall of said reservoir, movable under the action of an actuating means so that each step of movement of this actuating means corresponds exactly to an internal volume of the reservoir. Of course, this movable membrane will adapt, during its movement, to the internal walls of the reservoir.

[0037] The solution proposed by the invention is a device for temporary circulatory assistance or replacement of a patient's heart, the device comprising a circuit for diverting blood arriving at the heart to bring it out of the patient's heart, the diversion circuit using tubes connecting the following elements of said device together:

[0038] - at the level of the intake portion of the bypass circuit, a cannula inlet intended to be introduced into a patient's vena cava to withdraw blood from the venous system,

[0039] - at the ejection portion of the bypass circuit, an ejection cannula intended to be introduced into the patient's aorta or pulmonary artery to inject blood into the patient's arterial system,

[0040] - a pumping system comprising a reservoir with variable internal volume, located between the intake portion and the ejection portion, for the intake of the collected blood and then the ejection of this blood, said pumping system being controlled by control means so that the pumping of the blood, from its intake to its ejection, takes into account in real time the physiological needs of the patient and the hemodynamic state of said patient, the pumping system comprising at least a first pressure sensor, connected to the control means, arranged in the blood bypass circuit.

[0041] The device is remarkable in that the reservoir has a pear shape with a base of large diameter di reducing in its height to end at a top of small diameter d2 such that di is at least equal to seven times d2, i.e. di > 7d2, and in that a deformable membrane is fixed under the base of the reservoir, said membrane having an upper surface movable under the action of an actuating means so as to increase or reduce the internal volume of the reservoir, the membrane forming one of the surfaces of the reservoir with variable internal volume, said upper surface extending, in an initial state, along the plane of the base of the reservoir.

[0042] The term "pear" is understood to mean, in relation to the shape of the tank, that this tank has a relatively high diameter dl at its base, this diameter dl reducing in height - depending on the extension of the tank which is placed or oriented vertically, with its base in its lower part - slightly in the first millimeters then strongly to end at the top and its diameter d2. This tank is advantageously symmetrical with respect to a vertical plane passing through the center of its base and its top.

[0043] Thanks to the invention, the device according to the invention very precisely controls the speed of aspiration and ejection of the patient's blood as well as the quantities aspirated and ejected.

[0044] Advantageously, the above-mentioned control means are capable of imposing a force greater than 500 N (Newton) to suddenly accelerate or slow down a column of blood.

[0045] Other advantageous characteristics of the apparatus which is the subject of the invention are listed below. Each of these characteristics can be considered alone or in combination with the remarkable features defined above. Each of these features contributes, where appropriate, to the resolution of specific technical problems defined further in the description and in which the remarkable features defined above do not necessarily contribute. The latter may be the subject, where appropriate, of one or more divisional patent applications:

[0046] Preferably, the means for actuating the membrane is an (electric) cylinder, each step of the cylinder corresponding to an internal volume of the tank. The cylinder acts on the membrane via a central insert, embedded in the elastomer.

[0047] This central insert ensures the transmission of the movement imposed by the cylinder and imposes the deformation of the membrane via an optimal and deterministic profile. The cylinder is advantageously an electric cylinder allowing both significant power / force availability with a reactivity of the order of a hundredth of a second, which hydraulic or pneumatic cylinders do not currently allow to be achieved. Furthermore, an electrical system does not require significant maintenance.

[0048] Advantageously, the deformable membrane consists of an elastomer, preferably said membrane consists of a silicone.

[0049] Advantageously, the intake portion enters the tank, via an inlet conduit, oriented obliquely at an angle of between 10° and 60°, preferably an angle of between 30° and 50°, relative to the surface of the tank and upwardly - i.e. towards the aforementioned summit - at an angle of between 10° and 50°, preferably an angle of between 20° and 40°.

[0050] Preferably, the ejection portion enters the reservoir, via an outlet duct, through the top so that the outlet duct has the diameter d2 as its diameter. According to a different interpretation, the ejection portion comes from the reservoir which forms the outlet duct.

[0051] Thanks to this characteristic, associated with that of the reservoir and the inlet conduit, any bubbles generated when the blood enters the reservoir or when it is sucked in will be naturally led to escape through the ejection conduit and eliminated in or by a clean extraction circuit.

[0052] Advantageously, the tank is arranged vertically, the base extending along a horizontal plane, and the outlet conduit being located symmetrically, along a plane perpendicular and vertical to the extension plane of the base, at the top of the tank.

[0053] Of course, this vertical orientation of the reservoir associated with the presence of the ejection conduit at the top of the reservoir contributes to the effective elimination of air bubbles likely to appear in the blood diversion circuit.

[0054] Advantageously, the internal volume of the tank is between 80 cm3 (cubic centimeter) and 120 cm3, preferably between 95 cm3 and 105 cm3.

[0055] According to a preferred embodiment, the tank comprises at least two tabs intended to engage on a base for fixing the tank.

[0056] According to a preferred embodiment, the diameter d1 at the base of the reservoir is between 8 and 12 centimeters (cm), preferably between 9 cm and 11 cm, while at the top, the diameter d2 is between 0.9 and 1.3 cm, preferably between 1 m and 1.2 cm.

[0057] We understand with this example that di can be equal to more than ten times d2, or di > 10 d2 or even equal to more than eleven or 12 times d2 (di > 11 d2 or di > 12 d2).

[0058] According to a preferred embodiment, the first pressure sensor is arranged in the intake portion and in that this pressure sensor has a measurement time constant of less than 20 milliseconds, preferably less than 10 milliseconds, so that the control means modulate or stop the pumping of the blood taken when the pressure detected by the sensor reaches a threshold pressure value and / or the pressure increases / decreases beyond or below a threshold pressure acceleration / deceleration slope.

[0059] Advantageously, the first pressure sensor is located in or on the intake cannula, at a distance of at most 15 centimeters from the proximal end of said cannula, or in the bypass circuit between the intake cannula and the pumping system.

[0060] Indeed, by using the pressure information from the first sensor and the pressure information from the second sensor, it is possible to calculate, according to a method known to those skilled in the art, the viscosity of the blood at the level of the vena cava, that is to say at the location where the blood is taken, thanks to the measurements of the dynamic pressure losses.

[0061] This second sensor is possibly used to confirm the pressure measurement of the first sensor, in particular if the latter is defective or returns clearly erroneous information. In this case of a malfunction of the first pressure sensor, then the second pressure sensor located in the tank will fulfill the function of the first pressure sensor.

[0062] Advantageously, the pumping system comprises a third pressure sensor located in the ejection portion.

[0063] This third measurement of blood pressure makes it possible to refine the measurement of the patient's blood viscosity, this viscosity being used to slightly reduce or increase the two threshold values ​​(absolute and acceleration slope).

[0064] According to an advantageous possibility of the invention, the pumping system also comprises a blood oxygenation system, preferably this blood oxygenation system allowing the oxygenation of the blood at the ejection portion.

[0065] Advantageously, the distal end of the inlet cannula is located at a distance of at most 5 centimeters from the right atrium of the heart.

[0066] The present invention also relates to an admission cannula of a device for temporarily assisting or replacing the heart of a patient, the admission cannula being intended to be introduced at least partially into a vena cava of the patient up to a final position for withdrawing blood from the venous system by means of a pumping system to which said admission cannula is connected, the cannula comprising:

[0067] - a flexible, elongated main body for sucking up blood, and

[0068] - a lateral channel in particular for the introduction of a guide mandrel intended for to allow the intake cannula to be brought into its final position for blood aspiration,

[0069] the main body and the side channel being fixed to each other,

[0070] characterized in that:

[0071] - the main body is at least hollow on its distal portion in which said body comprises at least one blood suction orifice, the distal portion having a diameter dr when said distal portion is not filled, and

[0072] - the side channel is brought into an initial position against the main body thus constituting a first retracted position, and

[0073] - said retracted position is maintained by a temporary envelope housing said main body and said channel until the final position of the cannula,

[0074] wherein the temporary envelope, once removed, allows the main body and the side channel to occupy a second developed position in which the side channel is now distant from the main body and the distal portion of said main body is filled with a fluid so that the distal portion has a diameter dd.

[0075] Advantageously, the temporary envelope comprises at least one preformed tear line allowing said envelope to be torn and then removed.

[0076] Preferably, the diameter dd is at least equal to twice the diameter dr (dd > 2dr), preferably is equal to at least three times the diameter dr (dd > 3dr).

[0077] According to an advantageous embodiment, the main body is hollow over its entire length so that said main body has a diameter dr over its entire length when said body is not filled with fluid.

[0078] According to an advantageous embodiment, the side channel is fixed to the main body in the expanded position. Thus, the side channel is always connected and fixed to the main body, whether it is in its retracted position or in its expanded position.

[0079] Advantageously, the main body comprises a plurality of blood suction orifices, an end orifice and a plurality of side orifices arranged on the circumference of the main body.

[0080] Very advantageously, a rod - or semi-rigid guide - for piercing the septum, said rod being introduced into the lateral canal when this canal is in its developed position.

[0081] Thanks to the lateral channel of the cannula, a septum piercing rod can be introduced. Currently, with state-of-the-art cannulas, during ECMO ("Extracorporeal membrane oxygenation"), as soon as the left heart does not empty due to the absence of systole, clinicians are obliged to introduce a cannula into the left atrium to unload it (left unloading to avoid the risk of hemorrhagic pulmonary edema and the death of the patient). Thanks to this piercing rod and the lateral channel, the blood from the left unloading will be reinjected (recovered) into the blood bypass circuit of the heart support and replacement device.

[0082] Preferably, the main body is made of plastic or elastomer.

[0083] Advantageously, the fluid filling the distal portion of the main body or the main body consists of a liquid, preferably consists of water. Brief description of the figures.

[0084] Other advantages and characteristics of the invention will appear more clearly on reading the description of a preferred embodiment which follows, with reference to the appended drawings, produced as indicative and non-limiting examples and in which:

[0085] [Fig.l] is a schematic view of the device for temporary circulatory assistance or replacement of a patient's heart according to the invention.

[0086] [Fig.2] is a representation of an embodiment of the reservoir of the device temporary circulatory assistance or replacement of a patient's heart according to the invention.

[0087] [Fig.3] is a side view of the tank of [Fig.2].

[0088] [Fig.4] is another side view, from another angle, of the tank of [Fig.2].

[0089] [Fig.5] is a bottom view of the tank visible in [Fig.2].

[0090] [Fig.6] is a schematic top view of the tank visible in [Fig.2].

[0091] [Fig.7] is a representation of the reservoir of [Fig.2] connected or arranged in a base maintenance.

[0092] [Fig.8] is a view of the holding base used to hold the tank in a vertical position, from its base to its top.

[0093] [Fig.9] is a schematic sectional view of the membrane mounted on the piston, the membrane then being in its initial or resting position.

[0094] [Fig. 10] is a schematic view showing the upper surface of the membrane rising under the action of the central insert itself actuated by the piston and the cylinder.

[0095] [Fig. 11] is a schematic top view illustrating the central insert (and its diameter) relative to the membrane or the upper surface of the membrane (and its diameter).

[0096] [Fig. 12] is a schematic view from below of the membrane mounted on the piston.

[0097] [Fig. 13] is a sectional view of the membrane with its central insert mounted or installed in a dedicated cavity of the membrane.

[0098] [Fig. 14] is a representation of an embodiment of the various constituent elements of an admission cannula of the device for temporary circulatory assistance or replacement of the heart of a patient according to the invention.

[0099] [Fig. 15] is a view illustrating the intake cannula in its temporary envelope and an indication of its release for deployment of the intake cannula. Description of the embodiments.

[0100] The present invention will be described below in connection with a temporary circulatory assistance device for the heart of the type using a linear displacement cylinder 10 to suck and eject blood into a reservoir 11.

[0101] The device which is the subject of the invention is intended to be used during a degraded hemodynamic situation directly threatening the vital prognosis of the patient 12 (tissue perfusion pressure - PF - less than 50 mm Hg). It makes it possible to assist or supplement the heart 13 of a patient 12.

[0102] Referring to [Fig.l] or 2, the device which is the subject of the invention comprises a pumping system making it possible to partially or totally supplement the cardiac muscle by admitting a sufficient quantity of blood during the diastole phase of the cardiac cycle and by reinjecting it during the systole phase of said cycle.

[0103] The operator introduces an admission cannula (21 or 23 French or “Fr”, the FRENCH representing 1 / 3 of a millimeter) capable of drawing blood from the venous system of the patient 12 and an ejection cannula capable (17 or 19 French) of injecting the blood into the arterial system of said patient 12. We will see below that a specific admission cannula is advantageously used in the context of the present invention. Nevertheless, the admission and ejection cannulas that are usually used on the extracorporeal circulation market (CEC, ECMO, ECLS) are also compatible with the invention.

[0104] The operator can perform:

[0105] - a left heart / left heart setup for partial assistance in case left heart failure, by positioning the inlet cannula at the level of the right atrium, if the septum is pierced, the left atrium and the ejection cannula are discharged at the level of the abdominal aorta;

[0106] - a right heart / right heart setup for partial assistance in case of right heart failure, by positioning the inlet cannula at the level of a vena cava and the outlet cannula at the level of the pulmonary artery ([Fig.l] or 2);

[0107] - a right heart / left heart setup in case of right heart failure and the left heart, by positioning the inlet cannula at the level of a vena cava and the ejection cannula at the level of the aorta. In the latter case, the lungs are also bypassed and an oxygenation system 17 is placed in the bypass circuit to remove CO2 from the blood and charge it with O2 before reinjecting it into the body. This oxygenation system 17 is advantageously arranged after the reservoir 11, i.e. on the ejection portion 18 of the bypass circuit.

[0108] The cannulas can be placed percutaneously, in a cardiac and / or vascular catheterization room or in a resuscitation unit or by a UMAC SAMU unit (Mobile Circulatory Assistance Unit for UMAC and Emergency Medical Aid Service for SAMU), by introducing them through a peripheral blood vessel and bringing them close to the heart 13, at the level of the targeted veins or arteries. They can also be placed surgically in a surgical block, mixed implantation percutaneous puncture and surgical opening of the vessels.

[0109] These cannulas are connected to the pumping system by catheter-type tubes, also compatible with those usually used for a CEC to form on the one hand the inlet portion 19 and the ejection portion 18 of the bypass circuit.

[0110] Associated with this tube system of the portions 18, 19, an intelligent and independent purge system allows the elimination of air, this system being known in the state of the art. As we will see later, the reservoir has a shape and an arrangement also allowing the elimination of bubbles, that is to say to evacuate them through the outlet conduit 30 of the reservoir 11.

[0111] The pumping system consists of a tank 11 for storing momentarily a volume of blood necessary for the generation of the blood flow and a piston 31 arranged with an actuator 10, of the linear motor type or any other equivalent means making it possible to transmit a linear forward / backward translational movement to said piston 31 so as to vary the volume of said reservoir 11 and pump the blood. Control means 40 are provided to automatically control the actuator 10. In the same way as for the admission cannula, a specific reservoir 11 as well as a specific membrane 41, actuated by the piston 31, will be described below because they are advantageously implemented in the device for temporary circulatory assistance or replacement of the heart 13 of a patient 12.

[0112] The control means 40, controlling or commanding in particular the pumping system, are set up or implemented with a central unit 42 consisting of a computer, calculator or the like.

[0113] In the context of the present application, the object of the invention lies in providing a reservoir 11 having a specific shape as well as a membrane 70, the upper surface 71 of which forms the surface of the base 60 of the reservoir 11; said surface 71 being mounted to move under the action of an actuating means advantageously consisting of a central insert 72 set in motion by the action of a jack 10 extended by a piston 31.

[0114] The attached figures illustrate a preferred embodiment of the reservoir.

[0115] The attached figures illustrate a preferred embodiment of the reservoir.

[0116] This reservoir 11 thus has a pear shape with a wide base 60 of diameter d1 much greater than the diameter d2 at its apex 61, with a slight reduction in this diameter d1 from the base 60 over a first elevation portion of the reservoir 11 then a significant / rapid reduction until reaching the diameter d2. The inlet conduit 65, for the introduction of the aspirated blood, is oriented upwards, i.e. in the direction of the apex 61 of the reservoir 11, with an angle relative to this apex 61 of between 30° and 70°.Furthermore, this inlet conduit 65 penetrates obliquely into the reservoir 11, either with an angle relative to the surface of the reservoir of between 10° and 80°, this inlet conduit 65 not being perpendicular to the surface of the reservoir 11 and advantageously as tangential as possible, or at the smallest possible angle, less than 40° or even 30°. Such designs are taken to avoid the risks of hemolysis and to evacuate the air bubbles towards the top 61.

[0117] At the top 61 of the reservoir 11 enters the outlet or ejection conduit 62, with therefore its diameter d2. The reservoir 11 is arranged vertically, resting on its base 60 and its top 61 constitutes or determines the height of said reservoir 11. The reservoir 11 here has two ears 66 making it possible to mechanically block, by rotation in a blocking slot 67, the reservoir 11 on a base 68, visible in [Fig.6].

[0118] Finally, the reservoir 11 comprises a membrane 70 fixed under the base 60 of the reservoir 11, the upper surface 71 of this membrane 70 forming the lower internal surface of the reservoir. This membrane 70 is made of a flexible and elastic material, elastomer or other, at least at the level of its face or its upper surface 71, corresponding to the lower internal surface of the reservoir 11. Advantageously, the membrane 70 is entirely made of the same flexible and elastic material, such as an elastomer. This membrane 70 houses a central insert, not visible in the attached figures, provided with an actuating arm consisting of the piston 31, this piston 31 being fixed to a cylinder 10, hydraulic or pneumatic, capable of linearly moving this insert. The piston 31 is fixed to a jack 10 by means of a mechanical means 73 for engagement, fixing or connection to said jack 10.

[0119] Advantageously, the central insert has a diameter representing between 40% and 60% of the diameter of the membrane 70, or of the upper surface 71 of the membrane 70. It is recalled here that the diameter of the membrane 70 or the upper face / surface 71 of the membrane 70 is equal, or substantially equal, to the diameter dl of the base of the reservoir 11.

[0120] Thus, each step of movement of the cylinder 10 corresponds to an internal volume of the reservoir 11, this correspondence between the step of the cylinder 10 and the internal volume of the reservoir 11 being stored or recorded in the control means 40. Compared to an initial position in which the face or the upper surface 71 of the membrane 41 is not moved by the central insert, corresponding to a maximum internal volume of the reservoir 11, the insert is moved under the action of the cylinder 10 so that the upper surface 71 of the membrane 70 rises in the reservoir 11, thereby reducing the internal volume of the reservoir 11. As shown in [Fig. 10], the upper surface 71 of the membrane 70 rises in the reservoir 11 so as to reduce the internal volume and expel blood.When, on the contrary, one seeks to suck blood from the cylinder 10, via the piston 31 and the central insert 72, the internal volume of the reservoir 11 is increased by lowering or descending the upper surface 71 of the membrane 70, in other words by lowering / descending the central insert 72.

[0121] The initial position of the upper surface 71 of the membrane 70 occupies its initial position when this surface 71 is flat (see for example figures 11 and 12), at rest without any lifting action of the insert 72. This initial position of the membrane 70 or of its upper surface 71 corresponds to the internal volume of the reservoir 11, otherwise its maximum volume capacity.

[0122] Given the nature of the membrane 70 and the shape of the central insert 72, when the upper surface of the membrane 70 is raised, the contours of the latter 70 follow the internal walls of the reservoir 11 in a manner that is impervious to any liquid.

[0123] According to another advantageous aspect of the invention, the admission cannula measures approximately 70 centimeters (cm) - between 60 and 80 cm - and is introduced at the level of the upper part of the leg, as can be seen schematically in [Fig.l]: once fully introduced, it arrives in the immediate vicinity of the heart 13.

[0124] In [Fig. 13] the different elements making up such an intake cannula are visible, some in duplicate or according to two embodiment variants.

[0125] The intake cannula comprises at least one guide mandrel 80 for pushing the cannula for its introduction to its final position close to the heart 13 of the patient 12, one or other of these mandrels 80 (depending on the length desired) being used to serve with the septum piercing and suction tools 81.

[0126] This intake cannula also comprises two septum piercing and suction tools 81, each having a slightly different shape from the other in order to facilitate the work of the operator on the one hand to pierce the septum and then on the other hand to suck the blood from the patient 12. This piercing of the septum is envisaged to evacuate the excess blood in the left ventricle, the blood risking penetrating into the lungs which are nearby and thus causing pulmonary edema.

[0127] The guide elements 80 as well as the piercing and suction tools 81 are intended to be introduced into a lateral channel 82 fixed to the main body 83 of the intake cannula. This lateral channel 82 is fixed to the main body 83 by plastic connection, using a metal connection insert or by any other suitable means.

[0128] A particularity of the intake cannula according to the invention lies in its capacity to take two states: a first state called retracted in which on the one hand the lateral channel 82 is present contiguous to the main body 83 of the cannula and on the other hand the main body 83, being in the form of a hollow element, is not filled with fluid.

[0129] The main body 83 is in fact a hollow longitudinal body which can be filled and emptied, via the end wire conduits 84, with a fluid, advantageously a liquid. The main body 83 comprises at its distal end 85, close to the heart 13 when arranged in the vena cava, a longitudinal suction opening 86 and at its opposite proximal end 87, an opening 88 to allow the aspirated blood to enter the inlet portion 19 of the bypass circuit up to the reservoir 11.

[0130] The piston 31 and its central insert can rise so that the upper surface 71 of the membrane 70 reaches near the top 61 of the reservoir 11 so as to empty the entirety of the latter 61.

[0131] The main body 83 of the intake cannula also has the particularity of a plurality of lateral openings 89 - of the order of several tens - on the circumference of this body 83 from the longitudinal suction opening 86.

[0132] Furthermore, connection elements 90 are visible in this [Fig. 13] to be mounted on the proximal 87 and distal 85 ends of the main body 83. Two connection elements 91 can be noted between the main body and the lateral channel, these connection elements 91 making it possible to complete the connection or the fixing between the main body 83 and the lateral channel 82.

[0133] As stated previously, a major feature of the invention lies in the ability of the intake cannula according to the invention to adopt two states, one retracted and the other expanded. The retracted state of the main body 83 with the suction channel 82 is maintained using a mechanical means 100 capable of being destroyed or reabsorbed. so as to automatically release the main body 83 and the side channel 82 to the expanded state. In this case, this mechanical means 100 consists of a temporary envelope in which the empty hollow main body 83 and the side channel 82 attached against said body 83 are forced when in the retracted position.

[0134] The temporary envelope 100 comprises a longitudinal breakable line 101. This breakable line 101 makes it possible to cut the envelope 100 into two substantially equal parts and to remove the envelope 100 by pulling on a portion accessible to the operator, directly because the proximal end 87 of the cannula is not inserted into the body of the patient 12 or thanks to a protruding part of the envelope 100, not shown in the attached figures, from said body 83 making it possible to remove said envelope simply by pulling on it. The breakable line 101 is easily triggered by being initiated at the proximal end 87 simply by pulling on the two parts of this temporary envelope 100 or even using a pulling net, not shown in the attached figures, to release the breakable line 101.

[0135] This breakable line 101 consists of a tear line pretreated in terms of thickness, the nature of the material of the envelope and pre-piercing of this line. This tear line 101 causes or allows a fragility allowing or authorizing the peeling of the temporary envelope into two or more parts if there are a plurality of such breakable lines 101 on the envelope 100. The temporary envelope 100 is advantageously made of plastic.

[0136] Of course, this breakable line 101 is a means for releasing or removing this temporary envelope 100 maintaining the retracted state of the intake cannula, but any other mechanical means can be envisaged for tearing, cutting and / or removing the temporary envelope 100 so as to automatically allow or authorize the expanded state of the intake cannula.

[0137] An object of the invention also lies in having a minimum of pressure sensors 50, 51, 52 to anticipate any risk of collapse at the level of the vena cava during the blood aspiration phase.

[0138] The pumping system is controlled by the control means 40 and its central unit 42, in other words the flow rate of blood pumped by this system is controlled by the central unit 42. The present invention thus provides for arranging at least one pressure sensor 50 at the level of the inlet portion 19 of the bypass circuit, as close as possible to the vena cava. Obviously, this pressure sensor 50 is connected to the central unit 42 / control means 40, that is to say that the central unit 42 instantly receives the measurements from / coming from this pressure sensor 50.

[0139] Thus, if a pressure sensor 50 is available that can be arranged in the intake cannula, such a sensor 50 is arranged there. More surely, the pressure sensor pressure 50 can be installed on or in the bypass circuit, between the inlet nozzle and the reservoir 11.

[0140] In addition to the location of the pressure sensor 50, the important thing is that this pressure sensor 50 must have a measurement time constant of less than 20 milliseconds, advantageously less than 10 milliseconds, in order to detect very quickly and very regularly over time the blood pressure and any modification thereof.

[0141] The central unit 42 has computer means in which two types of alert have been programmed relative to the pressure detected in the inlet portion 19 of the patient's blood bypass circuit 12. First of all, a threshold level in absolute pressure value which, if reached, triggers a modification of the blood pumping, conventionally by reducing the pumping flow rate. Then, the second alert consists of the acceleration / deceleration of the pressure, between two pressure measurements over time: again, if this threshold slope (of acceleration / deceleration) is reached, the aspiration of the blood is modified, conventionally by reducing it or stopping it. Concerning the threshold slope, the predictive program of the evolution of the pressure conventionally uses the Reynolds number or the Reynolds wave. The Reynolds number corresponds to a dimensionless number which is used in fluid mechanics.This quantity makes it possible to characterize a flow, in particular the nature of its regime. It is thus possible to know whether a flow is laminar, transient or turbulent.

[0142] At each pulse, an order of magnitude of the volume of blood taken is of the order of 50 ml (milliliter) but this can rise to 100 ml, depending on the patient. A natural cardiac output is between 2.5 and 4.5 1 / mn / m2 (liter per minute per square meter). In other words, the larger the surface area of ​​a human body (and therefore its weight), the greater the blood circulation. In practice, to adjust the weight or volume of blood to be drawn at each pulse, the doctor considers the patient's weight 12 and deduces the volume at each pulse.

[0143] For a heart beating at 70 bpm (beats per minute), the suction time is approximately 0.56 seconds so that a normal flow rate is approximately 90 ml / s (milliliter per second per systole) or 5 1 / min (liter per minute). However, in practice, for a pulsating CEC / ECMO / ECLS, the doctor aims for an average flow rate of 3 or 4 1 / min. Thanks to the device according to the invention, it is possible to increase (or possibly reduce) the quantities of blood aspirated to correspond as closely as possible to the actual functioning of a heart, without risking collapse at the level of the vena cava.

[0144] The evolution of venous pressures at the level of the vena cavae and the atrium is very complex due to the very low pressures (2 to 4 millimeters of mercury on average) and the strong variations in pressure in the near atrial zone. The profile atrial pressure (right atrium) follows a curve with 3 maxima per cycle - with a maximum considered among these 3 maxima - corresponding to different events such as contractions of the right heart or relaxation of the tricuspid valves. The admission of blood into the device according to the invention is shifted relative to natural diastole by a shift of the order of approximately 0.25 seconds (i.e. between 0.2 and 0.3 seconds).

[0145] Thus, as an example, for the pressure threshold value (first alert) and the pressure slope or acceleration threshold value (second alert): - if the slope or acceleration of the measured pressure is 50% lower than it should be during a suction cycle, then this means that there is an imminent risk of collapse, and the central unit immediately slows down the suction flow; - if the absolute pressure falls below the threshold pressure value of 1 mm Hg (millimeter of mercury), then the central unit 42 immediately stops pumping for this suction cycle because the risk of collapse is very / too significant. Pumping restarts at the next suction cycle.

[0146] Of course, these slope and absolute threshold values ​​are variable depending on the patients 12. Furthermore, it should be noted here that the device according to the invention can operate with a quantity of physiological serum - adapted to its mixture in or with the blood of the patient 12 - present or not in the reservoir 11, when the aspiration in the bypass circuit begins. If this physiological serum is initially present in the reservoir 11, the operating cycle of the device according to the invention begins with the introduction of this quantity or a part of it into the body of the patient 12, which amounts to slightly increasing the overall pressure in the blood and therefore venous system of the patient 12. Whereas if the device begins to aspirate the patient's blood, without the presence of this quantity or this volume of physiological serum in the reservoir 11, the overall venous pressure of the patient will fall slightly due to the aspiration of the blood.

[0147] Another important factor for these threshold values ​​of pressure slope and absolute pressure lies in the determination of the viscosity of the blood of the patient 12. This is made possible by the presence of a second pressure sensor 51 present in the reservoir 11. Indeed, the dynamic pressure losses at the ends of a non-compliant resistive circuit correspond to the following formula:

[0148] sq = L [(Pi - Po) - Rq)]

[0149] where Pi and Po are the pressures at the inlet and outlet of the circuit, L the inertance of the system, q the flow rate and s the Laplace variable.

[0150] In the device according to the invention, the flow rate is very precisely measurable thanks to the position of the piston 31 in the reservoir 11. From this, the viscous friction resistance Rq proportional to the flow rate can easily be deduced. R is directly proportional to the viscosity (Poiseuille's law in laminar flow). It can also be noted that knowing the viscosity of the blood of the patient 12 makes it possible to determine the pressure at a location in the circuit, in this case the blood bypass circuit of the patient 12, knowing the pressure at another location in the circuit.

[0151] Thus, a third pressure sensor 52 is advantageously positioned in the ejection portion 18 of the bypass circuit so as to confirm or refine the calculated value of the viscosity of the blood of the patient 12.

[0152] This viscosity value of the blood of the patient 12 exerts a direct influence on the threshold values ​​of absolute pressure and slope to be defined to alert of a risk of collapse at the level of the vena cava, that is to say of the place of collection of the patient's blood. It is easily understood that the more viscous the blood of a patient 12 is, independently of the pressure, the greater the risk of collapse. In this case, the first and second alert values ​​are modified / lowered to integrate this characteristic into the risk of collapse at the level of the vena cava.

[0153] Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it includes all the technical equivalents of the means described as well as their combinations if these fall within the scope of the invention.

[0154] The arrangement of the various elements and / or means and / or steps of the invention, in the embodiments described above, should not be understood as requiring such an arrangement in all implementations. In any event, it will be understood that various modifications may be made to these elements and / or means and / or steps, without departing from the spirit and scope of the invention. In particular: - the shape of the membrane 70, it being understood that it can be imagined that there is only one upper surface 71 constituting in itself the membrane 70; - in the same way the insert 72 used to move the upper surface 71 of the membrane 70 can take any form or any manner as long as it allows this surface 71 or membrane 70 to be moved by increasing or decreasing the internal volume of the reservoir by a constant volume for each step of the cylinder 10 / piston 31 / insert 72.

[0155] The use of the verb “comprise”, “comprise” or “include” and its conjugated forms does not exclude the presence of other elements or other steps than those stated in a claim.

[0156] In the claims, any reference sign in parentheses cannot be interpreted as a limitation of the claim.

[0157]

Claims

1. Claims Device for temporary circulatory assistance or replacement of the heart (13) of a patient (12), the device comprising a circuit for diverting blood arriving at the heart (13) to bring it out of the patient's heart, the diversion circuit using tubes connecting the following elements of said device together: - at the inlet portion (19) of the bypass circuit, an inlet cannula intended to be introduced into a vena cava of the patient (12) to withdraw blood from the venous system, - at the ejection portion (18) of the bypass circuit, an ejection cannula intended to be introduced into the aorta or the pulmonary artery of the patient (12) to inject the blood into the arterial system of the patient (12), - a pumping system comprising a reservoir (11) with variable internal volume, located between the intake portion (19) and the ejection portion (18), for the intake of the collected blood and then the ejection of this blood, said pumping system being controlled by control means (40) so that the pumping of the blood, from its intake to its ejection, takes into account in real time the physiological needs of the patient (12) and the hemodynamic state of said patient (12), the pumping system comprising at least a first pressure sensor (50), connected to the control means (40), arranged in the blood bypass circuit, characterized in that the reservoir (11) has a pear shape with a base of large diameter di reducing in its height to end at a top of small diameter d2 so that di is at least equal to seven times d2, i.e. di > 7d2, and in that a deformable membrane (70) is fixed under the base (60) of the tank (11),said membrane (70) having an upper surface (71) movable under the action of an actuating means (72) so as to increase or reduce the internal volume of the reservoir (11), the membrane (70) forming one of the surfaces of the reservoir (11) with variable internal volume, said upper surface (71) extending, in an initial state, along the plane of the base (60) of the reservoir (11), in which the reservoir (11) comprises at least two tabs (66) intended to engage on a base (68) for fixing the reservoir (11).,

2. Circulatory assistance or replacement device according to claim 1, in which the actuating means (72) of the membrane (70) is a jack (10), each step of the jack corresponding to an internal volume of the reservoir (11).

3. Circulatory assistance or replacement device according to claim 1 or 2, in which the deformable membrane (70) consists of an elastomer, preferably said membrane (70) consists of a silicone.

4. Circulatory assistance or replacement device according to any one of the preceding claims, in which the inlet portion (19) enters the reservoir (11), via an inlet conduit (65), oriented obliquely at an angle of between 10° and 60°, preferably an angle of between 30° and 50°, relative to the surface of the reservoir (11) and upwardly - i.e. towards the above-mentioned (61) - at an angle of between 10° and 50°, preferably an angle of between 20° and 40°.

5. Circulatory assistance or replacement device according to any one of the preceding claims, in which the ejection portion (18) enters the reservoir (11), via an outlet conduit (62), through the top (61) so that the outlet conduit (62) has the diameter d2 as its diameter.

6. Circulatory assistance or replacement device according to any one of the preceding claims, in which the reservoir (11) is arranged vertically, the base (60) extending along a horizontal plane, and an outlet conduit (62) being located symmetrically, along a plane perpendicular and vertical to the plane of extension of the base (60), at the top (61) of the reservoir (11).

7. Circulatory assistance or replacement device according to any one of the preceding claims, in which the internal volume of the reservoir (11) is between 80 cm3 and 120 cm3, preferably between 95 cm3 and 105 cm3.

8. Circulatory assistance or replacement device according to any one of the preceding claims, in which the diameter d1 at the base of the reservoir is between 8 and 12 centimetres (cm), preferably between 9 cm and 11 cm, while at the top, the diameter d2 is between 0.9 and 1.3 cm, preferably between 1 m and 1.2 cm.

9. Circulatory assistance or replacement device according to any one of the preceding claims, in which the first pressure sensor (50) is arranged in the inlet portion (19) and in that this pressure sensor (50) has a measurement time constant of less than 20 milliseconds, preferably less than 10 milliseconds, so that the control means (40) modulate or stop the pumping of the blood taken when the pressure detected by the sensor (50) reaches a threshold pressure value and / or the pressure increases / decreases beyond or below a threshold pressure acceleration / deceleration slope.

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