Doctors delivered an electric shock to Vice President Dick Cheney's heart on Monday, jolting it back into a normal rhythm after they discovered an irregular heartbeat. This is the latest entry in an astonishing résumé of cardiac problems for the 66-year-old, who was back at work on Tuesday. Cheney has endured four heart attacks, two angioplasties, quadruple bypass surgery, a defibrillator implanted in his heart, aneurysms behind both knees, and a blood clot in his left leg. Isn't it time the vice president had a heart transplant?
Nope, he's way too healthy. Transplants are considered a last-ditch effort to save a patient. If the procedure works, he must take powerful immunosuppressants for the rest of his life. To be a transplant candidate, Cheney would have to suffer from end-stage heart failure, where the heart muscle is too weak to deliver blood to the rest of the body. A normal heart pumps out about two-thirds of the blood it holds, or in medical-speak, it has an ejection fraction of 65 percent. (This amounts to pushing a gallon of blood through the arteries each minute.) As of 2001, Cheney's ejection fraction was 40 percent—not great, but not sick enough to warrant a transplant.
According to the guidelines at most transplant centers, only the weakest patients can get a new heart. Most have an ejection fraction of just 10 percent or 15 percent. This is commonly the result of multiple heart attacks, in which portions of cardiac muscle die off from a lack of oxygen. (The heart enlarges to compensate for the diminished pumping capacity, but it still can't push out enough blood to keep the patient healthy.) Anyone with this much heart damage becomes a cardiac cripple: He'll be short of breath after taking just a few steps.
For a man who had his first heart attack at the age of 37 and went on to have three more, Cheney's not in bad shape. In fact, he's sustained only moderate heart muscle damage, thanks to attentive doctors and advances in cardiac care. He did land in the hospital with minor heart failure last year, but that was caused by medication he was taking for a foot problem. The drug caused him to retain fluid, and his heart couldn't handle the extra volume in his blood vessels. Unless Cheney's heart is severely weakened by something like a major heart attack, a viral infection, or deteriorating valves—and doctors have tried all the conventional treatments—he won't have any reason to queue for a transplant.
Many of Cheney's heart problems have to do with the organ's electrical system, which controls the rate of cardiac contractions. Because of all his heart attacks, it's likely that some of his heart cells no longer conduct electrical signals normally. But patients with irregular heartbeats almost never require transplants because there are much simpler treatments, which Cheney has already received. His defibrillator, which is also a pacemaker, monitors the lower chambers of his heart for fast, abnormal beats—say 300 a minute—that can bring on sudden cardiac death. (If his heart beats out of control, the device will jump-start the rhythm; this feels like being kicked in the chest.) As of this week, Cheney's doctors know that the upper chambers of his heart—i.e., the atria—can also have rhythm problems. But atrial fibrillation isn't fatal; at worst, it can cause stroke. Besides, Cheney's doctors patched him right up on Monday, as they have many times before.
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Explainer thanks Christopher Cannon of Brigham & Women's Hospital, Kenneth Ellenbogen of the Medical College of Virginia, and Hasan Garan of NewYork-Presbyterian Hospital.