Adrift in a clueless no-manвЂ™s-land, I felt my moods range from querulous to despondent.

I soon learned that the physicianвЂ™s warning, вЂњYou may be a little depressed for a time afterward,вЂќ would not do justice to the long, dumbfounding struggle against what seemed to be the sudden onset, at 51 years of age, of attention-deficit disorder or incipient senility. Mentally, however, I felt a bit hazy, a little disconnected and sometimes even lost. In a couple weeks I was out and about on slow but successively longer walks. The incision healed quickly and painlessly. An eight-inch incision below my right breast allowed the doctors to pass cameras and instruments between my ribs and then to repair my congenitally defective heart valve. Two liters of cold potassium solution stopped my heart, and for the next two hours the machine took over.

Surgeons inserted an inflatable clamp into my aorta to seal it off. My body temperature lowered to 25 degrees Celsius (77 degrees Fahrenheit)-deep hypothermia. As the venous blood passed through the oxygenator, it was cooled to prevent tissue damage. A dose of heparin kept my blood from clotting as it traversed the machineвЂ™s innards. This tube, and another attached to the artery, was connected to a cardiopulmonary bypass pump, also known as a pump oxygenator or a heart-lung machine. Through the vein they threaded a tube called a cannula into the right atrium, an upper chamber inside my heart. After the anesthesia took effect, surgeons made an incision in my groin to reach my femoral vein and artery. I was about to undergo open-heart surgery, an experience shared by about 500,000 people in the U.S. The last thing I remembered was the cold room with a stainless-steel ceiling. Many factors could be involved, but microscopic cell debris and bubbles generated by the machine are under suspicion. Recently, long-term studies of patients have shown that pumphead may worsen over time and persist for years.The condition, later nicknamed вЂњpumphead,вЂќ was thought to be short-lived and was often attributed to the general trauma of surgery. Since the inception of the machine, medicine has recorded cognitive decline inpatients hooked up to it.Previous techniques allowed only 15 minutes. The heart-lung machine, first used on humans in 1953, revolutionized coronary surgery by giving doctors an hour or more to operate on a still heart.

The long dark difficulties