Use of heparin to prevent lung microvascular thrombosis in patients administered aprotinin undergoing cardiac surgery for ischemic heart disease

Patients undergoing cardiac surgery administered aprotinin will be enrolled. Patients will be randomised to receive a pre-operative heaprin infusion or placebo. A lung biopsy will be taken to determine if pre-operative heaprin prevents the development of microvascular thrombosis in the lungs. Hypothesis. Heparin prevents the formation of blood clots in the lungs following cardiac surgery. The patients enrolled, the therapists and the data collectors will all be blinded.