Angiographic determination of disease-produced alterations of vasomotor tone in large coronary arteries.

Quantitative coronary arteriography was done before and after ergonovine and/or nitroglycerin in 24 patients. After nitroglycerin there was an average 18.6 +/- 3.9% increase in diameter of normal vessels over 2 mm in diameter, and a similar 19.3 +/- 8.7% increase in diameter of the same sized, normal appearing segments in subjects with coronary disease. In individual cases the luminal response to the drug was significantly more variable in "normal" segments of diseased vessels than in entirely normal arteries. Twenty-eight of thirty seven coronary stenoses dilated an average of 18 +/- 10.8% (range 3 to 43%) after nitroglycerin. Unequal dilation of stenosis and normal reference segment caused a 10% or greater change in calculated percent diameter stenosis in 16 lesions. Because they dilated less than would be predicted using a hypothetical geometric model to assess vessel reactivity, most of the lesions could be considered hyporeactive. Ergonovine predictably constricted normal coronary vessels in a relatively uniform fashion. Response of diseased arterial segments was more variable in a limited number of observations. Ergonovine partially antagonized the vasodilating effect of subsequently administered nitroglycerin, and larger than average or intracoronary doses of nitroglycerin had to be used to achieve the same degree of dilation seen with smaller doses in the absence of ergonovine. Disease of large coronary arteries focally alters their vasomotor tone and reactivity as gauged by responsiveness to nitroglycerin and ergonovine. Some implications of this are discussed.