Recent dramatic advances in heart surgery have led to the feasibility of human heart transplant and to the realization that the eventual solution to the problem of replacing a failing human heart, or in assisting a failing heart, may lie in the use of a man-made cardiac replacement or assist device.
At the present time, machines are in use in hospitals to take over the function of the natural heart while surgery is being performed on the heart. There have also been some prior art proposals in terms of total cardiac replacement devices and assist devices, but up to now no such means suitable for human usage has been devised, although considerable research and development is being undertaken in this area.
The objective of this invention is to provide a device of the above-mentioned character which hopefully will advance the state of the art a step closer to the time when a man-made heart can be successfully employed inside of the body as a permanent replacement for a human heart which has failed. For such an event to become a reality, a large number of problems must be overcome including such factors as a practical long-lasting power supply, creation of a sufficiently compact, efficient and durable pumping mechanism, discovery of materials which are compatible with human blood and tissue, maintaining hemolysis within acceptable limits, and other known criteria. Substantial progress has been made and is being made toward the solutions of some of these problems while work continues in the medical and engineering communities toward developing an eventually successful device.
It is believed that the present invention constitutes a significant advance in the art by offering a solution to several of the known and as yet unsolved problems in the art. More particularly, the invention provides in one form a total cardiac replacement device and in a second form a left or right ventricular assist means which may be employed while the recipient's heart is left intact. In both forms, the operation of the invention simulates quite closely the activity or functioning of the natural heart in terms of providing for pulsatile flow of blood, synchronous ventricular ejection, filling rate of ventricular sacs being a function of right and left atrial pressure and volume, and independent stroke volume of each simulated ventricle. In the total cardiac replacement embodiment, the device simulates the natural four chambered human heart, while in the ventricular assist embodiment, a single chambered pumping means is employed. Both forms of the invention utilize caged ball-type check valves of a proven commercial design. In both embodiments of the invention, blood is contained in atrial and ventricular blood compatible sacs and does not contact metallic parts of the device.
Other features and advantages of the invention will become apparent during the course of the following detailed description.