Surgery – Cardiac augmentation
Patent
1998-12-11
2000-04-18
Kamm, William E.
Surgery
Cardiac augmentation
A61M 112
Patent
active
060509325
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a control circuit for an implantable heart-assist pump of the back-pressure balloon type. The technique using an intra-aortic back-pressure balloon is well known for providing effective hemodynamic assistance to the left ventricle in the event of congestive heart failure: the balloon is inserted in the down branch of the aorta and is inflated during the diastolic phase of the heart cycle, and as a result injects an additional volume of blood into the network of arteries both upstream and downstream from its position. Deflated during the following heart systole, it decreases the load on the left ventricle thus enabling blood flow rate to be increased. The hemodynamic balance is positive: an increase in the injection fraction; a decrease in the telediastolic pressure. Thus, the balloon delivers additional energy which the ventricle is not able to supply, and the state of the patient is very significantly improved.
Implanted systems have already been proposed which make it possible to implement that technique in an entirely self-contained manner, for example as described in U.S. Pat. No. 5,222,980, or indeed in French application 96/00949 filed on Jan. 26, 1996 belonging to the same proprietor as the present application and entitled Pompe d'assistance cardiaque implantable du type a ballonnet de contrepression [An implantable heart-assist pump of the back-pressure balloon type].
Both of those documents describe a permanent implantable heart-assist pump inserted in the descending aorta, operating on the above-mentioned principle of a back-pressure balloon constituted by a flexible and elastic membrane in the form of a sleeve whose axis coincides with that of the aorta and which is put in the place of a segment of aorta that has been removed. The membrane is contained in a rigid chamber having substantially the same shape as the membrane at rest, and into which a hydraulic fluid is injected from an external generator, thereby compressing the membrane and thus reducing the volume of blood that it contains. Conversely, extracting the hydraulic fluid causes the inside volume of the membrane to increase, and thus the pump to be filled.
More precisely, an object of the present invention is to provide a control circuit for such an implantable heart-assist pump which controls the appliance so that its behaviour is as physiological as possible, i.e. it mitigates the heart failure without requiring excessive or antinatural effort from the weakened myocardium, and which, throughout the cardiovascular system, generates blood flow having characteristics, in particular pressure wave, that are as close to possible to those of a healthy organism.
Another object of the invention is to provide variable control of the pump that is adapted to the real hemodynamic demand of the patient, firstly to limit he energy consumption of the implanted appliance, and secondly, and above all, to disturb the natural hemeostatic equilibrium as little as possible, thus avoiding possible organic complications in the long term following implantation of the pump.
To this end, the invention provides a circuit for controlling an implantable heart-assist pump of the back-pressure balloon type of the above-specified type, i.e. comprising variable volume means co-operating with a separate volume through which blood flows for the purpose of modifying said volume through which blood flows cyclically and in controlled manner, the circuit being characterized in that it includes at least some of the means in the group comprising: means for sensing data representative of aortic pressure; means for sensing data representative of venous oxygen concentration; means for sensing data representative of aortic oxygen concentration; means for sensing data representative of heartbeat frequency; and means for sensing data representative of the myocardial contractility.
According to a certain number of advantageous characteristics: variable volume means, said control means including at least some of the means in the group comprising: means for c
REFERENCES:
patent: 3698381 (1972-10-01), Federico et al.
Kamm William E.
Synthelabo Biomedical ( Societe Anonyme)
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