Minimization of trauma to the aorta during cardiac bypass surgery can significantly reduce cognitive problems after surgery, according to an article in the January issue of the Journal of Thoracic and Cardiovascular Surgery.

“A surgical strategy designed to minimize aortic manipulations can significantly reduce the incidence of cognitive deficits in coronary artery bypass graft patients compared with traditional techniques,” said John W. Hammon Jr., M.D., lead author of the study.

The multidisciplinary team based at Wake Forest University concluded that surgical technique is the primary cause of cognitive problems after coronary artery bypass grafting. The team included psychologists as well as surgeons, anesthesiologists, and neuroradiologists.

In 1997, the same research team reported that they had reduced stroke and other acute complications following coronary artery bypass surgery from the national average of six percent of patients to less than one percent of patients at their institution.

In the new study of 237 patients, the team compared the standard method of coronary artery bypass using the heart-lung machine with surgical techniques that minimized movement of the aorta while still using the machine. Movement was reduced by using a single clamp that exerted significantly less force on the aorta than the standard cross clamp. Surgery without the machine was also compared.

The researchers gave the patients a battery of 11 psychological tests before surgery, at three to five days after surgery, and again between three and six weeks and at six months. The tests measured such things as fine motor function, verbal and nonverbal memory, attention and concentration.

In the week after surgery, at least 60 percent of the patients in all three groups showed neurological deficits. The number of patients with deficits declined steadily in both the group without the heart-lung machine and the group with minimal movement of the aorta. By six months, only 32 percent of the patients who didn’t use the machine and 30 percent of the patients who had minimal aortic movement had deficits, suggesting less permanent injury in both groups.

However, 57 percent of patients who had the traditional surgery had deficits at six months.

Based on monitoring techniques developed over the past 10 years, the team tracked emboli and gaseous bubbles going to the brain during the surgery. Team members believe the emboli are the cause of the neurological deficits.

Patients on whom the heart-lung machine was not used had significantly fewer emboli than patients who had traditional surgery - but that option is generally reserved for younger patients. Among patients who had the machine, those with minimal movement of the aorta had fewer emboli than those who had the traditional operation, but the difference did not reach statistical significance.