Noncoronary collateral myocardial blood flow.

This study shows that noncoronary collateral flow occurs in normal hearts after chronic coronary occlusion and with left ventricular hypertrophy in variable amounts (0.2 to 16 ml/100 gm/min). Luminal--left ventricular flow is greatest when the heart is arrested by aortic cross-clamping, falls significantly when perfusion pressure is lowered to 50 mm Hg, and increases slightly when blood viscosity is reduced (hemodilution). Our findings indicate that the heart which is arrested by aortic cross-clamping may not be anoxic.