Healthy Living
Coronary Artery Bypass - Complications
By David Perlmutter, MD, FACN
The coronary artery bypass operation, designed to increase blood flow through compromised coronary arteries, has entrenched itself as one of the most commonly performed surgical procedures in North America. Indeed, roughly 450,000 Americans undergo this procedure annually despite the fact that often times the procedure is simply unnecessary. A recent report in the Journal of the American Medical Association revealed that close to half of the coronary artery bypass operations performed in the United States are done for "inappropriate reasons." A study by Harvard Medical School's department of Public Health recently revealed that 84% of patients who obtained a second opinion after being scheduled to undergo a heart bypass procedure were told that they did not need it. During that study’s two year follow-up there were no deaths in the group of patients who canceled their surgeries based upon the second opinion.
While cardiac surgeons are quick to point out that angina may be completely alleviated in approximately 80% of patients undergoing bypass procedures, the fact that mortality rates as high as 8% are still being reported in some major centers is often downplayed. But perhaps an even more troubling and equally downplayed statistic is the fact that about 25% of patients who undergo the coronary artery bypass procedure will suffer some form of significant neurologic or cognitive complication, with some of these deficits representing permanent abnormalities.
Extensive research by Dr. Ola A. Selnes of the Johns Hopkins University in Baltimore published in the highly respected journal Lancet and presented at the 122nd Annual Meeting of the American Neurological Association has confirmed what has long been suspected regarding neurological consequences of the bypass procedure. As Dr. Selnes has stated, "Both neurologic and cognitive complications continue to be reported after coronary artery bypass despite ongoing refinements in surgical techniques and anesthesiology…." Cognitive deficits are estimated to affect at least 25% of patients after coronary artery bypass surgery. Most deficits are assumed to be transient and relatively minor. The reality, however, is that few long-term studies document this assumption. In this report, Dr. Selnes evaluated various parameters of cognitive function prior to surgery and re-evaluated patients one month, one year, and five years after surgery. Assessments included tests of language skills, both verbal and visual memory, psycho-motor skills, and tests of attention. The results were clearly troubling. As Dr. Selnes stated, "A higher proportion of patients were doing significantly worse five years after coronary artery bypass surgery than we anticipated." The most striking abnormalities were found in tests of visual memory with clearly 23% of patients demonstrating a significant decline in this area. These studies also demonstrated prominent decline in tests of verbal memory and language skills.
During the coronary artery bypass procedure, patients are placed on a cardio-pulmonary bypass machine, allowing oxygenation of the blood while the heart is stopped. Dr. Selnes speculates that micro emboli, or small blood clots, formed while patients are on the bypass pump, may produce microscopic brain lesions that subsequently lead to long term degeneration of brain cells. Further, localized areas of poor blood supply to the brain have long been recognized as consequences of bypass surgery. But the actual mechanisms by which bypass surgery causes subsequent cognitive decline have yet to be fully elucidated. When these mechanisms are better defined, modifications of present surgical technique may allow a reduction in the incidence of these sometimes devastating consequences.
In our efforts to pursue the most advanced, high-tech techniques available for alleviation of our common medical problems, it is important to recognize one of the most fundamental doctrines of medicine - above all, do no harm .