Effects of intracoronary nitroglycerin administration on poststenotic vascular diameter before and following transluminal coronary angioplasty

: Percutaneous transluminal coronary angioplasty (PTCA = TCA) was performed in 38 patients with coronary single vessel disease. Coronary angiograms were analysed to detect the influence of mechanical as well as nitroglycerin-induced dilation on organic stenoses, prestenotic and poststenotic coronary segments and non-stenosed reference vessels. 28 patients (group I) were evaluated retrospectively. Bolus injection of 0.5 mg of nitroglycerin (NTG) was followed by an increase in all measured segments: prestenotic segments +15.4%, stenoses +17.9%, poststenotic segments +39.3%, reference segment of a nonstenotic vessel +29.9% above control value before NTG. Subsequent mechanic dilation of stenosis by 108.3% resulted in no further significant increase of poststenotic diameters (+42.6% above control value), while diameters of reference vessels decreased (+9.7% above control value). In order to demonstrate whether this behaviour was due to a loss of NTG activity at the end of TCA, we attempted to reinduce vasodilation in another 10 patients (group II) by a second intracoronary bolus injection of 0.5 mg NTG. In these patients NTG injection before TCA resulted in an increase in poststenotic diameters as well as in reference vessels (21.2% and 14.0% respectively above control value). At the end of TCA an increase in the poststenotic diameter could be found to 22.1% above control value, while diameters of reference vessels had markedly decreased (4.1% above control value). The second injection of NTG resulted in an increase of poststenotic as well as reference segments (39.3% and 17.4% respectively above control value).(ABSTRACT TRUNCATED AT 250 WORDS)