When Bill Clinton underwent quadruple coronary-bypass surgery on Labor Day, the former president, like most Americans who have similar operations, spent time hooked up to a heart-lung machine while surgeons rerouted blood vessels to his heart. With luck and his relative youth and health going for him, Clinton, 58, hopefully will rebound in both heart and mind from the surgery, in which doctors replace clogged arteries to the heart with veins and arteries taken from elsewhere in his body. But many people who go through the procedure -- as 305,000 Americans did in 2001, the latest year for which figures...