Surgery – Cardiac augmentation – Aortic balloon pumping
Patent
1998-12-11
2000-02-29
Kamm, William E.
Surgery
Cardiac augmentation
Aortic balloon pumping
600 16, A61N 1362
Patent
active
060303360
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a pressure generator/regulator device 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, in such a system, the present invention provides a generator for controlling variations in the pressure of the hydraulic fluid, and thus for controlling the operation of the pump.
One of the objects of the invention is to provide a generator structure which optimizes the overall energy balance of the pump firstly to limit the consumption of energy by the implanted appliance, and secondly and above all to make the pump operate in as physiological manner as possible by generating blood flow in the cardiovascular system as a whole having characteristics that are as close as possible to those of a healthy organism. It can be seen below that the generator of the invention makes it possible to achieve these objects while, mechanically speaking, it remains simple, robust, and compact in structure, which characteristics are essential for a system that is implanted.
In another aspect, it can also be seen that the device of the invention can be used in a purely passive manner, i.e. without delivering net additional energy to the system (it does not have drive means, or said means are inactive), the heart providing all of the energy demand on its own. Under such circumstances, it is shown that the device of the invention nevertheless makes it possible to modify in advantageous manner the pressure wave while behaving essentially as additional elastance (elasticity factor) serving, for example, to compensate for deterioration in the natural elasticity of the arterial network.
Under such circumstances, the device of the invention behaves essentially as a pressure regulator, and that is why the general term "generator/regulator devices" is used to cover both possible ways of implementing the invention, respectively actively and passively. It will also be observed that the same device can be used at different times either in active mode or
REFERENCES:
patent: 4439186 (1984-03-01), Kuhl
patent: 4938766 (1990-07-01), Jarvik
patent: 5814102 (1998-09-01), Guldner et al.
patent: 5924975 (1999-07-01), Goldowsky
Kamm William E.
Layno Carl H.
Synthelabo Biomedical ( Societe Anonyme)
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