Abstract
In 12 patients with exertional chest pain, coronary angiography was periormed and quantitative measurements of coronary artery (CA) diameters were made before and during cold stimulation (four normal CA patients and eight fixed CA stenosis patients). The left main CA; proximal, middie and distal anterior descending and circumflex segments; and small intramyocardial CAs (0.4 to 1.0 mm) usually showed only minimal and similar degree of vasoconstriction (average diameter reduction 6%) during cold stimulation in both normals and CA disease (CAD) patients. Magnitude of vasoconstriction differed among some CA segments measured; the left main CA segment (0 ± 2%, mean ± SD) usually did not change while distal segments (−10 ± 10%) usually demonstrated greatest percentage vasoconstriction. Coronary stenoses and CAs filled by collaterais did not demonstrate increased magnitude of vasoconstriction compared to other CAs. Results of other CA segments were also similar comparing patients with and without CAD. The minimal degree of vasoconstriction observed in these CA segments does not appear to account for the large increase in coronary resistance reported during cold stimulation in CAD patients.
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