Corrosion cast of a canine myocardial microcirculation with capillaries and collecting venules. Blue arrows indicate redistribution of flow into the underperfused microcirculation form larger normal perfused veins, red arrows indicate washout and clearing during balloon release and subsequent inflow from collaterals and the unobstructed coronary arteries. Coronary sinus pressure and the concomitant pressure increase in an occluded coronary artery showing redistribution of venous flow in the underperfused arterial vascular bed during balloon occlusion. As soon as the systolic plateau is reached the occlusion automatically is released and washout and clearing of the microcirculation occurs. Note the ECG on the top showing the heart beat interval. As seen the time of pressure elevation in the venous vascular bed varies according to pathophysiologic conditions of the heart during injury, the heart rate and ventricular force.