Trial Balloon in the Aorta

The 45-year-old Brooklyn woman had survived the first few critical hours after a severe heart attack and should have been on her way to recovery. But part of the muscle in the wall of her left ventricle, the heart's main pumping chamber, was too badly damaged to snap back spontaneously. Six hours after the patient reached the hospital, she was in shock--blue in the face and in a cold sweat. Doctors at Brooklyn's Maimonides Medical Center wanted to give her circulation a boost, at least for a few hours. If her heart could be relieved of its work load, and at the same time strengthened by an increased flow of blood through its own coronary arteries, it might regain enough power to carry on by itself. But how to give it that boost?

Maimonides, fortunately, is one of the world's leading centers for research in artificial heart aids. Last year its heart specialists pioneered in implanting temporary plastic ventricles (TIME, June 3, 1966). This time Dr. Adrian Kantrowitz and his colleagues had a new and simpler idea: to put a balloon in the aorta and make it serve as a pump. The balloon had an added attraction. It does not require major chest surgery on an already weakened patient.

Pumping on Signal. Surgeons injected a local anesthetic into the patient's thigh and cut into the femoral artery. They then threaded a flexible plastic tube up the artery and the aorta until a deflated balloon at its end was about level with the heart (see diagram). The outside end of the tube led to an electrically operated pump filled with nonflammable, nonexplosive helium. The patient was connected to an electrocardiograph, whose signals could control the pump.

With the balloon in place, the ECG signals were fed into a relay to regulate the pump's timing. When the patient's left ventricle contracted naturally, it sent a modest amount of blood into the aorta, but under insufficient pressure. A fraction of a second later, when her aortic valve had closed, the ECG signal made the pump fill the balloon with helium. This forced the blood in the aorta not only up and down, but also back to the roots of the coronary arteries, thus increasing the oxygen supply to the heart muscle. Meanwhile the ventricle relaxed and began to refill with blood. The pump emptied the balloon in time to allow a flow of blood from the next heartbeat.

The doctors kept the woman patient on the balloon pump for seven hours, during which her color improved and her skin became warm and dry. Then they removed the balloon. Since then, her heart has performed adequately on its own. Further recovery has been as normal as that of other heart attack victims, and last week, six weeks after the operation, her doctors were considering a date to send her home.

For wide-open future-use possibilities, the Maimonides doctors note that 15% of all heart-attack victims suffer shock complications.

This file is automatically generated by a robot program, so reader's discretion is required.