Evaluation of coronary collateral development by regional myocardial function and reactive hyperaemia.

The development of collateral vessels was induced by repeated brief left circumflex coronary artery occlusions in 11 conscious dogs. Subendocardial segment shortening in the central ischaemic area and the ischaemic marginal area and transmural wall thickening in the centre of the ischaemic area were measured together with circumflex coronary flow. Changes in regional myocardial function and reactive hyperaemia were determined daily. The rate of recovery of myocardial function after collateralisation was almost identical in both regions. Before myocardial contractility was restored reactive hyperaemia was greatly attenuated. These data strongly suggest that collateral flow is distributed uniformly over the ischaemic bed and that substantial areas of myocardial tissue at risk are salvaged from ischaemia as a result of effective collateral circulation.