A new study links biomarker of brain injury to microemboli occurring during cardiac surgery
Research Activities, October 2010, No. 362
An increase in blood levels of a biochemical marker of neurologic damage (S100ß) in patients who undergo heart bypass surgery is associated with the number of microemboli (microscopic gaseous, lipid, or thrombus particles) observed in the blood that passes through the cardiopulmonary bypass circuit, a new study finds. Neurologic injury, ranging from subtle behavioral symptoms to stroke, is known to be a complication of cardiac surgery. The formation of microemboli is considered the principal mechanism in causing such damage, according to the researchers. They detected microemboli in blood leaving the bypass circuit in 67 of the 71 patients studied, with a mean of 707 and a median of 341 emboli. Most of the patients had increased blood levels of S100ß after surgery, with the postoperative level of the marker higher for patients in the middle than the lowest third (tercile) in terms of microemboli count, and higher again for patients in the top tercile. Three percent of the patients died after surgery while in the hospital, 1 percent experienced a transient ischemic attack (or mini-stroke), and 1 percent suffered a stroke.
The study enrolled 71 patients undergoing coronary artery bypass surgery at a single hospital between October 2004 and December 2007. Measurement of serum levels of S100ß were taken before and within 48 hours after surgery. Doppler ultrasound was used to measure the number of microemboli exiting the cardiopulmonary bypass circuit. Based on their findings, the researchers suggest that redesign of the cardiopulmonary bypass circuit to prevent microemboli from leaving the circuit may reduce the risk of neurologic injury. The study was funded in part by the Agency for Healthcare Research and Quality (HS15663).
More details are in "Micro-emboli from cardiopulmonary bypass are associated with a serum marker of brain injury," by Robert C. Groom, M.S., Reed D. Quinn, M.D., Paul Lennon, M.D., and others in the March 2010 The Journal of Extra-Corporeal Technology 42(1), pp. 40-44.