Coronary vasomotion in response to sympathetic stimulation in humans: importance of the functional integrity of the endothelium

Abstract

The coronary vasomotor response to the cold pressor test was studied with use of quantitative coronary angiography in 32 patients without evidence of coronary artery disease and 55 patients with such disease; in a subset of 22 patients (9 with normal coronary arteries and 13 with coronary artery disease), the effects of the cold pressor test were compared with the effects of the endothelium-dependent vasodilator acetylcholine with simultaneous intracoronary Doppler flow velocity measurements to assess the influence of endothelial dysfunction. The cold pressor test induced vasodilation of 8.9 +/- 5.7% in all 77 analyzed vessel segments of the group with normal arteries (p less than 0.01). In contrast, in patients with coronary artery disease, the 52 analyzed stenotic segments were constricted by -12.1 +/- 9.5% (p less than 0.01), the 57 analyzed vessel segments with luminal irregularities were constricted by -8.9 +/- 5.2% (p less 0.01) and 40 (85%) of 47 angiographically normal segments also were constricted by -7.0 +/- 4.9% (p less than 0.05). Preserved vasodilating capability was demonstrated by intracoronary nitroglycerin in all analyzed segments. In nine patients with normal coronary arteries, the analyzed vessel segments were dilated in response to both the cold pressor test and intracoronary acetylcholine by 10.9 +/- 5.4% and 13.4 +/- 4.7%, respectively. In contrast, in all 13 patients with coronary artery disease, vasoconstriction of identical vessel segments by -9.1 +/- 3.7% and -23 +/- 10.4%, respectively, was observed after both the cold pressor test and intracoronary acetylcholine. Intracoronary propranolol did not significantly affect either the vasodilative response in 11 normal coronary arteries (11.3 +/- 4.4% before and 8.6 +/- 4.3% after beta-blockade) or the vasoconstrictor response in 8 atherosclerotic coronary arteries (-11.4 +/- 4.6% before and -14.6 +/- 5.3% after beta-blockade). The dilation of normal and the constriction of atherosclerotic coronary arteries with cold pressor testing exactly mirror the response to the endothelium-dependent dilator acetylcholine. Endothelial dysfunction in coronary atherosclerosis resulted in a loss of normal dilator function and permitted vasoconstrictor responses to sympathetic stimulation. Thus, coronary vasomotion of large epicardial arteries in response to sympathetic stimulation by the cold pressor test in humans is intimately related to the integrity of endothelial function.