Acute Effects of Elevation of Coronary Sinus Pressure

The acute physiologic effects of the aorta to coronary sinus anastomosis of Beck have been studied. The evidence presented shows that arterialization of the coronary sinus results in a small retrograde flow from the sinus through capillaries into the occluded artery and that such retrograde flow supplies from 14 to 25 per cent of the normal myocardial oxygen requirement. It is suggested that this is insufficient to maintain normal myocardial contraction, but probably prevents ventricular fibrillation. However, when the sinus is arterialized in the presence of normal or reduced coronary flow electrocardiographic and coronary inflow data show that there is myocardial anoxia. This is probably due to the restriction in capillary outflow and results in an expansion of the coronary vascular bed.