Total Artificial Heart

Doctors also continue to work with the concept of implanting totally artificial hearts, which would alleviate the shortage of donor organs.

In some cases, the heart is so damaged by disease that adequate support can only be obtained with a total artificial heart. Earlier versions of the total artificial heart included two single pumps, one to replace the right ventricle and one to replace the left ventricle, and the power source was outside the body.

The first implantation of a total artificial heart into a human was done by Cooley on April 4, 1969, in a 47-year-old man who could not be weaned from the heart – lung machine following left ventricular aneurysm resection. The intent was to support the patient until a donor heart could be found. The total artificial heart itself was connected to a large external power unit, which unfortunately severely restricted patient mobility. The total artificial heart performed adequately for 64 hours until transplantation. The donor heart also functioned well, but the patient died of severe lung infection 32 hours after transplantation. This case clearly demonstrated that a total artificial heart could be used safely and effectively in a human as a bridge to transplantation.

Other implantations of permanent artificial hearts soon followed. These implantations were fraught with complications, and the devices and power consoles were large and cumbersome .However, researchers continued to develop a smaller implantable device in which electrical power is transmitted across rather than through the skin. These pumps are quieter and appear to be less likely to create the blood clots that plagued recipients of the earlier devices. Because this newly developed totally artificial heart can be nearly, if not completely, implanted under the skin, the risk of infection should be lower.

Abiocor Total Artificial Heart

On July 2, 2001, as part of an FDA sponsored clinical trial, surgeons performed the first implantation of the AbioCor total artificial heart in a 59-year-old man suffering from end-stage heart failure. The AbioCor totally implantable replacement heart is designed to sustain the circulation and extend the lives of patients with end stage heart failure who have suffered irreversible left and right ventricular failure, for whom surgery or medical therapy is inadequate, and who would otherwise soon die. The AbioCor is the first total artificial heart to be used clinically that is fully implantable and communicates to external hardware without penetrating the skin. The device utilizes special communication system that allows it to be powered and controlled by signals transmitted across intact skin. 14 patients received the AbioCor as a final therapy. Thromboembolism was a significant side effect in this group of patients, and there were two pump failures. However, compared with the known rates of infection for implantable systems, infections in this trial were relatively rare. The longest surviving patient was supported for 512 days; most of these days lived at home with a good quality of life.

Use of a total artificial heart is associated with serious complications. The most frequent complications are infection, severe bleeding after surgery, and thromboembolism. Potentially serious but less frequent complications are kidney, liver, lung, and brain dysfunction.

Life-threatening infections have been the most important complication for patients being supported permanently by a total artificial heart. Factors that invites this infection include the tissue trauma associated with surgical implantation, contamination of the implanted device,  depression of the body’s immune defenses,  the large amount of foreign material present on the surface of the device; and use of  tubes, catheters, and other devices that are necessary for the care of these patients. Infections can occur at any point during total artificial heart support.

Postoperative bleeding is a frequent and serious complication of total artificial heart implantation. It generally occurs in half of total artificial heart recipients. factors that contribute to this high bleeding incidence include associated liver dysfunction, the extensive surgery and long time required for implantation, and the necessity for postoperative anticoagulation therapy. The necessity for postoperative anticoagulation therapy requires that a proper balance be established between preventing thrombosis and allowing blood to clot, through the careful management of anticoagulant therapy.

Many advances have been made in the field of mechanical circulatory support, and future generations of these devices hold great promise. Although heart transplantation remains an alternative for a select group of patients, it is currently not available to the vast majority of patients who are dying from heart failure.In the next few years, a long term device should be widely available for the treatment of heart disease and terminal heart failure, hopefully sparing many of these patients from an untimely death.