Assessment of coronary vasoreactivity and the microcirculation

Summary

Coronary vasoreactivity, both in large epicardial arteries and in the microcirculation, is crucial to adapt blood flow to the requirements of the myocardium. The coronary circulation is regulated by endothelium-derived vasoactive substances as well as circulating hormones and autocoids and the sympathetic nervous system. The endothelium is in a strategic anatomical position between the circulating blood and vascular smooth muscle cells and hence a target of both circulating hormones and autocoids as well as cardiovascular risk factors. The latter cause endothelial dysfunction both in large coronary arteries and in the microcirculation. This is mainly due to an inactivation of the L-arginine-NO pathway and the production of reactive oxygen species, and in turn adhesion molecules, cytokines and chemokines. Endothelial dysfunction can be assessed with various invasive and non-invasive methods allowing for diagnostic studies as well as monitoring the effects of various cardiovascular drugs. Endothelial dysfunction is an early step in the atherosclerotic process preceding structural vascular changes, but predictive of the development of plaques and plaque rupture and in turn clinical events.

Introduction

Since the introduction of coronary angiography by Mason Sones in the 50ties and percutaneous peripheral and later coronary angioplasty by Andreas Grüntzig in the 70ties, these diagnostic and interventional...