“…Myocardial blood flow, measured with microspheres, is highly heterogeneous under basal conditions without coronary obstruction, even within the same myocardial layer, and regional flow varies by a factor up to seven from one area to the other (1,2,4,5,12,15,21,25,31). Regional matching of O 2 supply to demand was demonstrated by a fair correlation between regional coronary blood flow and oxygen uptake in the normal pig heart without obstructed coronary vessels (2).…”