Of heart and mind

May 2006

The impact of heart surgery on the brain is being tested in a study that could have a major impact on how and under what circumstances the surgery is performed.

Report: Diane Squires

As a cardiac surgeon, Professor Julian Smith is often approached by patients or their relatives who are concerned about subtle changes in personality after they or their loved ones have had heart surgery.

In his role as Monash University's Head of Surgery and Monash Medical Centre's Head of Cardiothoracic Surgery, Professor Smith has encountered family and friends of heart patients who have noticed memory loss, lack of balance or impaired vocabulary. Sometimes the patients do not admit any changes have occurred or they may not be aware of them, he says.

Now, a study being undertaken by Monash's Psychology and Surgery departments is determining whether heart surgery does, in fact, result in subtle changes in brain function and whether certain types of heart surgery may be more likely to affect cognition.

The study, by PhD candidate Ms Kathryn Bruce and her supervisors, Associate Professor Stephen Robinson, Dr Greg Yelland and Professor Smith, assesses cognition before and after heart surgery.

As well as testing motor coordination, memory and verbal fluency, the study uses the Subtle Cognitive Impairment Task (SCIT) test, developed in 2001 by Dr Yelland and Dr Robinson and doctoral students Mr Timothy Friedman and Mr Chris Hutchison, all from the School of Psychology, Psychiatry and Psychological Medicine. See also: Focus on cognitive impairment.

Ms Bruce says the SCIT test, which relies on the subconscious, gives reliable results because participants cannot practise or remember answers from previous sessions.

"We get a clearer picture of whether there have been any changes to cognition because people can't cheat on the test the second or third time they do it," she says.

The tests are performed on heart patients before surgery, then one week and again three months after surgery to determine whether cognitive impairment is present and ongoing.

The study is looking at 90 patients aged over 55 who have undergone coronary artery bypass, valve surgery or keyhole and robotically-assisted surgery.

Initial indications show all surgery has some impact on cognitive function, but the effects of different types of surgery are yet to be assessed.

Professor Smith says his team wants to help guide doctors to use the surgical techniques that provide the best outcomes overall.

The impact of different types of surgical procedures could have major implications for how and under what circumstances they are performed in the future.

"It is important to know whether there are any differences in cognitive function between the ways in which surgery is done to know what overall impact it is having," he says.

"This study may lead to further modifications in the way we do surgery, or further adoption of minimally invasive surgery if we find that other surgeries have a greater cognitive impact.

"It may be that the stress on the body as a whole is less with keyhole surgery, which may in turn have less of an impact on cognitive function, or we may find there is nothing we can do about it and that all surgery results in some cognitive impact."