Artificial Heart
There is no doubt that cardiac transplantation has a role and provides beneficial relief of suffering in selected individuals. The one-year survival rate is more than 80% and the 10-year survival rate is close to 50% for transplantation. This far exceeds the dismal survival rate obtained with the left ventricular assist devices that at two years is less than 20%. Following left ventricular assist device a transplant is necessary within one to six months. This calls for two operations within six months in very sick individuals. This is a major disadvantage of assist devices. Most important, there are fewer than 4000 donor organs available worldwide per year. The cost of two operations within six months is prohibitive as well as physically and mentally traumatic. A functional total arti¬ficial heart would be a dream come true.
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- I. ELECTRIC TOTAL ARTIFICIAL HEART
The first artificial heart implant was carried out by Dr. Denton Cooley in Houston, Texas, in a 47-year-old man with intractable heart failure using the Liotta artificial heart developed by Domingo Liotta. This artificial heart was based upon the laboratory work of Dr. Michael DeBakey. - II. LEFT VENTRICULAR ASSIST DEVICE A. Systems
Left ventricular assist devices are implanted only in patients who are eligible for cardiac transplantation. These devices are used as bridges to transplantation. There are three left ventricular assist devices presently available: - III. IS THERE A LOGICAL ROLE FOR VENTRICULAR ASSIST DEVICES?
There are approximately fewer than 3000 donor organs available worldwide per year. In the United States alone, in 1999, 2184 patients with heart failure underwent heart transplantation. When a left ventricular assist device is implanted a donor heart must be available within approxi¬mately 3 months for the patient to maintain survival and quality of life. - IV. NEW FRONTIERS
A ray of hope has been generated by the work of Dr. M. H. Yacoub, who describes a novel strategy: a com¬bination of surgery and physiologic hypertrophy. The surgical process involves implantation of a left ventricular assist device and medical therapy with a drug, clenbuterol, a beta-2-agonist which induces reverse remodeling of the left ventricular myocardium and subsequent physiologic myocardial hypertrophy. This strategy improves left ven¬tricular contractility and ejection fraction sufficiently to allow explantation of the assist device (the Harefield protocol). - BIBLIOGRAPHY
Brown, B. G., Crowley, J. et al. Is there any hope for vitamin E? JAMA,