The effect of external pressure diastolic augmentation on regional myocardial perfusion in experimental myocardial...

The effect of external pressure diastolic augmentation on the distribution of coronary blood flow following coronary occlusion was studied in 36 dogs using radionuclide tagged macroaggregated albumin and an electromagnetic flow meter. Collateral flow, approximately 30% of normal flow immediately following occlusion, increased spontaneously by approximately 50% over the first 4 h. Two and 4 h of immediate, maximal external pressure diastolic augmentation resulted in only slightly greater mean increases in collateral flow than that which occurs spontaneously during the same time period. Reduction of the level or delay in onset of diastolic augmentation resulted in even less increase in collateral flow to the ischemic area. Mean coronary flow increased only 6% with external pressure diastolic augmentation. Since neither distribution of coronary blood flow nor total coronary blood flow was significantly altered by external pressure diastolic augmentation, this technique appears to be relatively ineffective in improving oxygen delivery to acutely ischemic myocardium in the dog.