(HealthDay is the new name for HealthScoutNews.)
TUESDAY, June 10 , 2003 (HealthDayNews) -- A new study gives visual evidence that doing coronary bypass surgery "off the pump" is better for the brain than conventional surgery, researchers say.
"The pump" is medical slang for a heart-lung bypass machine. Until recently, all coronary bypass operations -- about 500,000 will be done in the United States this year -- were done by stopping the heart and having the machine support the body's circulation.
But many patients undergoing such surgery have complained about mental confusion, memory loss and other neurological problems afterwards. Some have suffered strokes. So in recent years, more and more of these operations have been done while the heart is still beating, a technique that requires considerable surgical skill.
The new report, delivered June 10 to the American Heart Association's Second Asia Pacific Scientific Forum in Honolulu, says off-the-pump surgery dramatically reduces the incidence of micro-emboli, tiny blood clots that can block arteries and kill brain cells.
The study included 60 bypass patients, half of whom were put on the pump, while the other half had off-pump surgery, says Dr. Jeffrey D. Lee, an associate professor of surgery at the University of Hawaii and leader of the research group.
All were outfitted with Doppler ultrasound probes on each side of the head, directly over the arteries that feed the brain. Micro-emboli produce high-pitched chirps, whose number and timing were painstakingly recorded by listening sonographers.
Off-the-pump patients averaged 26 micro-emboli, compared to an average of 771 for those on the pump, Lee reports.
"Others have looked at the bypass pump and have shown that the pump does originate emboli," Lee says. But a critical part of the study was the time when those emboli were produced -- not during important phases of the operation, such as the moment when a tube was placed in an artery or when the bypass operation was concluded.
In both groups of patients, only about 20 percent of the emboli were produced at such times, while 80 percent were generated at random times. "This takes the surgery out of the loop and shows that it is the heart-lung machine that is responsible," Lee says.
The study provides more support for a growing trend to use off-the-pump surgery for bypasses, Lee says. Nationally, about 30 percent of bypasses are being done off the pump, the American Heart Association estimates, and the percentage is growing.
Lee says he is doing more and more off-pump procedures in his practice "as my experience and comfort level has increased." The same is true across the country, he says.
In addition to avoiding brain damage, other studies have shown that off-pump surgery also reduces blood loss and gets patients out of the hospital quicker, thus reducing the cost of the procedure, Lee says.
The report adds a step to the evolution of off-pump surgery, says Dr. Richard C. Pasternak, director of preventive cardiology at Massachusetts General Hospital and a spokesman for the American Heart Association. It went "from a good theoretical idea to something that was doable, but without evidence that it would make a difference, to getting that evidence," he says.
"This adds clear evidence of what the mechanism is," Pasternak says. "It fits the original theory."
And Pasternak adds a word of reassurance to people who have had or will have operations using the heart-lung machine. "The vast majority of people who have had bypass surgery over the years have not had neurological problems," he says.