Quo vadis collateral blood flow? A commentary on a highly cited paper.

This text is a commentary on the highly cited paper by Maxwell-Hearse-Yellon describing the amount of collateral blood flow in several species of mammals after coronary artery occlusion. The measurement of collateral blood flow, an academic exercise in previous times because of its invariance and the futility of changing the degree of adaptation under chronic conditions, has reached new importance because collateral vessel growth (presently called arteriogenesis) can now be manipulated with growth factors, their genes or peptides. The early successes and failures are discussed and a plea is made for the rigorous application of goldstandard methods (like in the Maxwell-Hearse-Yellon paper) to avoid disappointments in the new science of 'therapeutic angiogenesis'.