Pre- and postoperative circulatory support employing ventricular bypass with local heparinization and blood filtration for 5 to 72 hours was conducted in 5 patients with myo cardial infarction. All of these patients had critical cardiac conditions due to cardiogenic shock. Postoperative introduction of ven tricular bypass support was not effective in 2 patients because of bleeding due to removal of hemorrhagic infarcted myocardium, or because of failure to gain sufficient blood re turn from the ventricle. However, the pre operative use of ventricular bypass was ef fective in promoting the ultimate survival of 2 of the 3 patients who underwent surgery.