ABSTRACT
INTRODUCTION Long before the era of interventional cardiology, Heberden was the first to describe the phenomenon of angina pectoris, already including the walking-through phenomenon. This symptom was later attributed to recruitment of collateral vessels during exercise. However, the following two centuries favored the concept of coronary end-arteries rather than that of a functional human coronary collateral circulation.1 With the advent of percutaneous coronary intervention (PCI) in 1977, antegrade revascularization of stenotic vessels became a mainstay for treatment of coronary artery disease (CAD). Because one-third to one-fifth of CAD patients are not amenable to PCI and some are not candidates for surgical revascularization either, the need for alternative methods like promotion of collateral growth has arisen. In parallel, invasive methods for the assessment of coronary collaterals have been introduced and evaluated.2,3
Quantitative collateral assessment by invasive means has markedly advanced insight into the functional relevance of the coronary collateral circulation: In CAD, the amount of collateral flow is a pivotal protective factor with respect to infarct size4,5 and mortality (Fig. 14.1).6 Infarct size is determined by the duration of coronary occlusion, the anatomic area (or myocardial mass) at risk for infarction, collateral flow to the infarct-related artery, myocardial preconditioning and oxygen consumption at the time of occlusion.7
