FR2550086A1 - Auxiliary artificial heart - Google Patents

Abstract

The auxiliary artificial heart is an apparatus intended to allow functioning of a heart suffering from a myocardial insufficiency such that it is incapable of fulfilling its functions, and that the only currently possible alternative is transplanting. It is composed of a pump, a single cavity of variable volume weighing a few hundreds of grams driven by a low electric power, the whole being easily transportable by the receiver. Only one easily performable operation which causes little trauma is necessary, which operation consists in covering the pericardium with a flexible fabric of low elasticity which is biologically acceptable and in joining up the pericardium thus reinforced to the skin. It can allow normal life, and help to cure a long-time myocardial disorder. It can also allow a practically normal life while waiting for a transplant. It can ensure prolonged survival in the case of an irreversible terminal insufficiency.

Description

I - PRINCIPLE
The heart behaves like a suction and pressure pump controlling the
always moving in the same direction, from the veins and atria to the
ventricles, and ventricles to the arteries.

The direction of circulation is determined by the valves separating
atria and ventricles, and those separating ventricles and aorta or artery
pulmonary.

If the valve system is in working order, it is possible to ensure
circulation, even if the heart is inert, by cardiac massage
external.

Indeed, a resting heart has its activities dilated to the maximum. Compression
externally has the same effects as a contraction, and sends the content of
ventricles in the arterial system. When the compression stops, the heart re
laced, expands, filling its cavities, its ventricles in particular
due to the valve clearance. A new compression is then equivalent to a new
systole.

The purpose of the system we are proposing is to induce rhythmic compressions
ques followed by periods of rest on the heart in place of the subject, by a mechanism
reliable, inexpensive, on, replacing manual compressions of cardia massage
than external.

II - DESCRIPTION
The compressor unit consists of a pump, single cavity of variable volume,
the variations in volume being caused by the displacement of a piston or
a membrane, driven by a motor.

The cavity is connected, via a pipe, to the space included
between the heart and the pericardium, and filled with physiological fluid.

Each reduction in the volume of the cavity, which sends the liquid between the heart and the pericardium, corresponds to compression of the heart. When the piston or membrane returns to their rest position, they cause the heart to relax and fill, through the play of valves as in the case of an external cardiac massage.

III - PRACTICAL IMPLEMENTATION 10) The pump comprises a body, with a capacity slightly greater than the volume of the two ventricles of the heart. It can be made of metal or plastic.

The body is closed by a movable piston or membrane, the displacement of which causes a reduction in the internal volume equal to the capacity of the two ventricles, ie on average 160 ml.

20) The motor can be a rotary or reciprocating motor, driving the movements of the piston or of the membrane, or else an electromagnet opposing the action of a spring and receiving rhythmic pulses. These pulses can be triggered by the repolarization wave of the heart itself, amplified electronically, and the pump then has its rhythm synchronized with the heart's own rhythm in place.

The maximum power required must be that giving the maximum pressure supplied by the right ventricle (i.e. 25 mm of mercury) so as to avoid pulmonary hypertension, sufficient however to ensure oxygenation of the elongated subject in the event of complete arrest of the autonomous cardiac activity.

30) The interior of the pump is placed in communication with the intra-pericardial cavity, via an orifice with a cross-sectional area equal to the sum of that of the aorta and the pulmonary artery, so as to ensure the same ejection time as the ventricles.

40) It is necessary to strengthen the pericardium, to avoid its dilation, with a non-elastic tissue, either appneurotic or bio-tolerated synthetic.

IV - FUNDING
When the heart failure is decompensated, the dilation of the cavities no longer causes sufficient strengthening of the contraction to empty the ventricles which, therefore continue to dilate. The circulation is no longer assured, anoxia sets in, and the anoxic myocardium deteriorates until it reaches the irreversible stage.

If the proposed system is installed before this final stage, the auxiliary heart provides help for myocardial contractions in the form of compression by physiological fluid which can reach up to 25 mm of mercury, i.e. 100% of the work of the ventricle right, and 29% of the work of the left ventricle in normal, ambulatory work.

This is equivalent to putting the heart to rest while normalizing its oxygenation, and this can allow healing of a transient episode.

In the most severe case, the proposed system can allow for an ambiguous ambulatory survival, and allow to wait the time it takes for a transplant.

V - ADVANTAGES 10) This artificial heart consists of a single cavity with variable volume, without valve. It is easy to carry out. Small in volume (that of normal heart chambers), it can be attached to the outside of the body. The electrical equipment is simple, and energy can be supplied by rechargeable batteries or rechargeable batteries.

 It is therefore inexpensive.

20) It requires only a much less traumatic intervention than a transplant; the risks of rejection of the communication channel and reinforcement of the pericardium are much less, do not require the heavy immunosuppressive treatment.

30) I1 can be produced in large series at low cost and allow many awkward patients to wait a long time for a transplant, in relatively satisfactory comfort.

40) In the event of a breakdown of the electrical system, it can be operated manually by the patient or his entourage, pending repair.

50) I1 leaves the heart in place, putting it to rest, and may perhaps allow its recovery.

Claims (1)

 R E V E N b I C A T I O N S  N "1 - Auxiliary artificial heart characterized by a unibody pump without valve or valve, whose interior volume filled with physiological saline or any other physiological liquid communicates with the cavity between heart and pericardium. - The variations in the interior volume of the pump cause compressions and decompressions of the heart muscle in the same way as an external cardiac massage. - These volume variations are controlled rhythmically by an electromagnet which, under the effect of electric pulses, lowers the diaphragm or the piston of the pump, reducing the internal volume of the pump and compressing the heart. A spring located under the membrane or the piston of the pump, compressed by the electromagnet, returns to the pump, by relaxing, its initial volume, decompressing the heart. - The electrical pulse is sent to the electromagnet by the closing of an electrical circuit triggered by the depolarization wave of the heart itself. The pump, actuated at the same time as the contraction of the ventricles, brings to these ventricles the assistance of the pressure which it brings, thus reinforcing this contraction in a proportion which can be 100% for the right ventricle, and 29% for the left ventricle. The heart nevertheless retains all its autonomy and its possibilities of adaptation to the requested effect.  N0 2 - Auxiliary artificial heart, according to claim NO 1, characterized in that the pump motor is a rotary electric motor driving at a desired rate increase and decrease in the volume of the pump, usable in the case where the heart does not no longer has any autonomous possibility of contraction.