The present study reveals that, in our experimental infarct model, only left ventricular bypass is effective in reducing the infarct size within the region at risk when pumping is initiated 3 hrs after the onset of acute ischemia. It also confirms that, although high flow through the bypass system is effective in the large infarct model, total left ventricular decompression is not a necessary criterion for the recovery of the infarcted myocardium.