All tissues and organs eventually begin to fail. Sometimes they can be repaired. Sometimes it’s possible to compensate for deteriorating function. But the time comes when the only way to preserve health and extend life is to replace worn out body parts.
Some body parts, such as heart valves and knee joints, are eminently replaceable with synthetic equivalents. Others are so complex that transplantation seems the better bet. One organ, the brain, is so entwined with our sense of self and humanity that it defies replacement. To wit, if we could build an artificial brain and upload a stored version of the patient’s personality and memories, then would the recipient be the same person—or even human?
One thing is clear: replacement parts are already saving lives and improving the quality of lives. The benefits of a replacement heart valve are profound and there are few, if any, ethical concerns. Still, we may want to place some limits on body part replacement. Not everything that is technically possible is desirable.
There are different types of replacement parts. There are direct, permanent replacement parts that take the place of the failed organ or tissue. There are indirect replacement parts that take over part or all of the function of the natural organ or tissue. And there are external devices that handle the function of a failed organ—sometimes while waiting for a transplant. Several organs can be transplanted from people who died from unrelated injuries. It may one day be possible to use whole organs harvested from other species (xenografts). We are already able to use acellular material (called small intestine submucosa) harvested from other species.
Blood was one of the first critical body parts to be replaced. (Teeth, discussed in Chapter 12, were another.) The discovery of blood groups, the Rhesus (Rh) factor, anticoagulants, and simple techniques for storage and transfusion enabled today’s blood banks. Let’s hope they don’t need a bailout.
I wrote previously about the seminal contributions of an unlikely trio: oil tycoon John D. Rockefeller, Nobel Prize winning biologist Alexis Carrel, and American adventurer Charles Lindbergh. They laid the foundation for organ transplants and the heart-lung machine.
John Heysham Gibbon, Jr. deserves the lion’s share of credit for bringing the heart-lung machine to fruition. Gibbon came up with the idea independently, pursued it despite others’ skepticism, and devoted nearly two decades of his life to heart-lung machine research and development. He started by experimenting on cats, progressed to dogs, teamed up with IBM Corp., and performed the first successful surgery using a heart-lung machine in 1953. The patient, a young woman named Cecelia Bavolek, reluctantly became a celebrity.
In addition to describing in detail how Gibbon developed the heart-lung machine, the 30-page chapter tells the story of the development of cardiovascular catheterization—initially for diagnostic purposes and eventually enabling procedures that competed with coronary artery bypass graft surgery. The story starts with Werner Forssmann’s unauthorized catheterization of his own heart, additional developments by innovators including André Cournand, Mason Sones, and Charles Dottering, and the development of balloon angioplasty by the flamboyant refugee from East Germany, Andreas Gruentzig.
The chapter wraps up with the development and implantation in 1960 of the first artificial heart valve by surgeon Albert Starr and engineer Lowell Edwards. Today, there are both mechanical and bioartificial replacement heart valves, and their use has become routine. The latest development is minimally invasive implantation of artificial aortic valves using a stent-like device that is delivered via a catheter and pushes the natural valve leaflets aside.
Progress in repairing and replacing body parts—particularly in the cardiovascular system—has been nothing short of amazing. How can we best ensure more of the same? Most of the progress has been driven by individuals. I’m not going to deny reality: today most medical research is conducted by large organizations—and often run by committees. But we need to keep our minds open in case we encounter another Werner Forssmann, the sort of person who does not ask permission to make great discoveries.
Next time: Repair or Replace? Part II
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