Y. researchers investigate heart surgery side effects

Heart surgery patients typically suffer some neuro-cognitive decline after being put on heart-lung bypass. Now research out of BYU indicates the risk of mental decline may be greater for patients who have a particular blood phenomenon.

In those individuals, when the blood is removed from the body and cooled to reduce the brain's oxygen need during surgery, blood platelets "aggregate rather aggressively," says Ken Solen, professor of chemical engineering at Brigham Young University, who studies how blood reacts to man-made materials.

When the platelet aggregates are sent back into the body's circulatory system, they reduce or stop blood flow, leading to complications like stroke and stroke-related symptoms.

Researchers believe if the findings can be repeated in other studies, patients whose platelets react that way could be given already available medications to prevent or minimize the negative effects, he says. Solen believes physicians could screen for the blood effect before surgery and intervene with one of the anti-platelet medications that will block the abnormal platelet activity.

Working with LDS Hospital's heart surgery team, led by Dr. James Long, the BYU researchers evaluated 339 patients slated for a particular type of open-heart surgery. After controlling for other factors, the number was reduced to 45, who were then given neuro-cognitive tests the day before and several days after heart surgery by BYU associate professor of psychology and neuroscience Ramona Hopkins. Of the 45, 20 were found to have the platelet phenomenon, and those patients also exhibited significantly more decline in verbal fluency and in mental activities related to self-control and goal-directed behaviors following the surgery.

What the researchers don't know, Solen says, is why. He's hoping to identify a more standard lab test that would let clinical labs correlate blood findings with cognitive outcomes.

It has long been standard practice to cool both the patients and the blood that is being recirculated by machine during open-heart and major blood-vessel surgeries.

Although it's generally well-recognized that patients placed on heart-lung bypass suffer some mental decline, there's no definitive answer on how long those effects last or whether they're permanent.

While the BYU study found "significantly greater decline in patients with the blood phenomenon than in patients who did not have it," he says, it's also not clear whether that extra decline continues over the long-term or if it tapers to become more like the typical decline noted in patients whose platelets do not react that way.

Research indicates about a third of the population seems to have the abnormal platelet behavior and researchers believe it has something to do with genes and chromosomes, although they're not sure of the mechanism. It does seem to run in families.

Results of the study are being published today in the journal Perfusion.

Besides Solen, Long and Hopkins, researchers for the study included former BYU graduate student Matthew Hall and pathologist Dr. S. Fazal Mohammad of the University of Utah. The study was funded by a grant from the Deseret Foundation at LDS Hospital.

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