Quantitative coronary angiography: evidence of a sustained increase in vascular smooth muscle tone in coronary artery stenoses.

Quantitative analysis of coronary angiograms was performed to evaluate the effect of either 0.8 mg nitroglycerin (NTG, n = 54 stenoses) or 20 mg nifedipine (NIF, n = 42 stenoses) sublingually, or of both drugs combined (n = 50 stenoses) on coronary artery stenosis diameter. The narrowest diameter (DSTEN) in each stenosis was measured in multiple angiographic projections (2-7, mean: 4) before, and 10 min after administration of the drugs. Coronary artery stenoses were defined as concentric with DSTEN differing less than 25%, or as eccentric with greater than 25% in various projections. To establish the long-term effects of the vasodilator drugs measurements were repeated in 36 stenoses after an average 23-day interval in identical projections before and after NIF plus NTG sublingually. NTG dilated DSTEN from 1.19 mm to 1.53 mm (+28%) on average in 25 of 54 stenoses. After NIF, DSTEN increased in 20 of 42 stenoses from 1.21 mm to 1.59 mm (+31%) on average. The combination was most effective with DSTEN increasing from 1.24 mm to 1.85 mm (+49%) on average in 31 of 50 stenoses. The dilatory response was found to be related to stenosis morphology: lesions with an elliptical residual lumen responded significantly more often to NTG plus NIF than did lesions with a circular residual lumen; and of limited duration: interval angiography showed a restored increased vascular tone which could be released again with sublingual administration of NTG plus NIF.(ABSTRACT TRUNCATED AT 250 WORDS)