Morphological change in myocardium in goat recovered from profound left ventricular failure with cardiac assist device.

With left ventricular assist device (LVAD) pumping, goats having induced-heart-failure were salvaged. LVAD was weaned off when the heart seemed to recover, and animals were kept alive for about 1 month after the pump removal. After termination of the experiments, infarction area was 10 to 50% of the left ventricular wall including the septum. The longer pumping period against severe infarction resulted in the thinner wall thickness of normal myocardial area. The myocyte diameter (Dm) was microscopically measured in 3 layers: sub-epicardium, middle myocardium and sub-endocardium. Subendocardial Dm was largest, and followed by Dm in middle myocardium, and then Dm in subepicardium. These results coincided with results obtained from a control-heart experiment except that Dm in the normal area of recovered hearts was thicker. The relation between Dm and left ventricular external mechanical work computed from left ventricular pressure-volume relation showed an adaptive control mechanism of myocardium.