Transplanted Hearts

Many a surgeon dreams of the day when, like the mechanic faced with a worn-out fuel pump, he will be able to dip into a bank of human spare parts and fix up his patient with a replacement for.an ailing organ -even one so vital to life as a kidney or the heart itself. So far, apart from the difficulty of obtaining such spare organs, two obstacles have seemed insuperable: 1) the surgical difficulties of making all the necessary blood-vessel connections in time, and 2) the immune reaction which causes a recipient to manufacture antibodies that destroy any foreign blood-containing tissue. Last week the American College of Surgeons meeting in Atlantic City heard reports of encouraging progress toward overcoming both obstacles.

Hearts have been transplanted from one dog to another and have taken over the job of pumping the recipient animal's blood, reported Dr. Watts R. Webb, who worked on the project with Dr. Hector S. Howard at the University of Mississippi. The heart alone would be too difficult to move, said Dr. Webb, because of the many blood-vessel connections to the lungs. So his team tried transplanting the heart in combination with both lungs, and then with the left lung only.

Dog to Dog. Their method: in the anesthetized donor animal, after the heart's major blood vessels were closed, the organs were perfused with a solution to wash out all blood which might later cause clotting. Then the organs were cut out and stored in a preservative solution at 40DEG F. while the recipient dog was prepared. This animal was hooked up to a heart-lung machine which did its blood pumping and breathing as long as necessary. Then its heart and lung or lungs were cut out and discarded. Now the surgeons took the chilled organs from the refrigerator and implanted them. The aorta had to be sewn in place with the utmost care--a time-consuming process -but the great veins leading into the right heart could be hooked up with simple surgical couplings.

After the heart and both lungs were transplanted. Dr. Webb reported, the "spare-part" heart soon took over and kept beating as long as 28 hours before the experiment was abandoned. But the animal could not breathe by itself, without the aid of the lung machine, because the transplanted lungs had no nerve connections. If only the left lung was transplanted, the recipient's right lung still had nerve connections to transmit the breathing reflexes. In dogs so treated, the transplanted heart beat normally, and the unmatched lungs breathed, for as long as 18 hours.

Man to Man. If the method is ever to be tried on a human heart-disease victim, where would the spare heart come from? Perhaps, suggest the doctors, from an accident victim. By keeping heart-lung systems chilled for eight hours and getting them to work again, the surgeons have now shown that there would be more than enough time for such a surgical swap. Indeed, as optimistic Surgeon Webb sees it the one major problem remaining is the immune reaction.

On this score, a husband-wife team from Johns Hopkins University, Plastic Surgeon Milton T. Edgerton and Chemist Patricia J. Edgerton report that skin grafts from one strain of mice to another normally died within nine days, but could be made to live as long as 38 days if they were retransplanted several times at four-day intervals. This suggested that an organ donated for spare-part use might be conditioned so that it would no longer stimulate the recipient's system to produce antibodies. And a team at the University of Minnesota reported on work with rats and rabbits suggesting that the recipient might be conditioned not to reject transplanted tissues from another individual, or even another species.

Said Dr. Webb: "When this problem of immunity is overcome, there should be no major obstacle to transplanting human hearts, or even using animal hearts in humans. It will probably take five to ten years, but the surgeons will be ready. In fact, I believe we're ready now."

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