Calcium Microemboli and Microfilters in Valve Operations

Fatal microemboli occurred in 3 of 100 consecutive patients having aortic valve replacement; 2 occurred during perfusion before the microfilter era, and 1 occurred intraoperatively despite the use of in-line filters. In all 3 patients cerebral symptoms were present immediately postoperatively, and each died of severe brain damage. On postmortem examination cerebral calcium microemboli were verified in only 2 patients, although the brain of each patient contained minute infarctions. However, calcium particles were found in the kidneys of all 3 patients. Thus the kidneys proved to be the best place for detection of calcium emboli on postmortem examination. Although the microfilters currently available effectively prevent microemboli during extracorporeal circulation, the surgeon should be aware that embolization can also occur immediately after discontinuation of perfusion. The means of protecting the patient from this are discussed.