The behavior of antithrombin III, alpha 2 macroglobulin, and alpha 1 antitrypsin during cardiopulmonary bypass

We serially measured concentrations of three protease inhibitors, antithrombin III, alpha 2 macroglobulin, and alpha 1 antitrypsin in patients with coronary artery and valvular heart disease during extracorporeal circulation. Assays for immunoreactive antiproteases and for functional antithrombin III were performed on plasma samples obtained at selected intervals before, during, and after cardiopulmonary bypass. Significant reductions of all protease inhibitors occurred at some time during cardiopulmonary bypass, although patterns of change were dissimilar for the two patient groups. A return toward preoperative levels was observed after cardiopulmonary bypass was discontinued, but antithrombin III remained diminished in the patients with coronary artery disease. The acute serial changes in this group of alpha globulins is evidence of their participation during the dynamic stress of extracorporeal circulation. Their timely intervention as serine protease antagonists deters sustained thrombogenesis and fibrinolysis during cardiopulmonary bypass.