THE TREATMENT OR THE DISEASE?: Long blamed for post-op cognitive decline, the heart-lung machine may be off the hook as researchers learn more about the long-term impacts of vascular disease on the brain--not just the heart
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In the months after he had surgery to fix his defective heart valve, Bruce Stutz didn't feel quite the same. It wasn't his physical fitness that was subpar, although that did require some post-op retraining, but rather his mental capacity. "I couldn't muster the concentration to deal with the problem," he wrote in a 2003 article for Scientific American.

During surgery, Stutz had been hooked up to a heart–lung machine, also called a cardiopulmonary-bypass pump, for the two-hours of a procedure to keep his blood oxygenated and flowing while his heart was stopped. He found that he was not the only one who, after time on the pump, had felt their brains bogged down by simple tasks.

A 2001 study in The New England Journal of Medicine found that of 261 heart disease patients who had been kept alive during surgery with the pump, 42 percent showed cognitive decline five years after the surgery, even after adjusting for age. "Interventions to prevent or reduce short- and long-term cognitive decline after cardiac surgery are warranted," the authors, led by Mark Newman of the Duke University Medical Center, concluded. And a study published earlier this year in The Annals of Thoracic Surgery, led by James Slater, a cardiothoracic surgeon at the Mid-Atlantic Surgical Associates in Morristown, N.J., supported the previous findings, showing that lowered levels of oxygen in blood flowing to the brain during surgery did correlate to increased risk of suffering from the mental impairment dubbed "pump head".

But some noticed a flaw in these studies. Most that supported the pump head condition had focused only on patients who underwent pump support during surgery for coronary artery bypass grafting (CABG) but had not controlled for those with the disease who had different types of procedures, such as off-pump surgery or no surgery at all. Could there be something missing in the data?

That's what Ola Selnes, a professor of neurology at The Johns Hopkins Hospital in Baltimore, and his colleagues set out to find. Their six-year study—published this month in The Annals of Thoracic Surgery—examined 326 people who had coronary disease and 69 who didn't. Of those who did had the disease: 152 had undergone the CABG procedure using the pump; 75 had off-pump surgery; and 99 had nonsurgical treatment. After testing subjects at several intervals starting before surgery and ending six years later, they found that those with healthy hearts retained their levels of cognitive functioning after the operation, whereas the patients with coronary disease experienced about the same amount of cognitive decline—regardless of the sort of treatment they had. The results call into question years of assumptions about the long-term safety of the pump.