Effects of nifedipine on coronary perfusion; recent assessment by parametric digital subtraction.

The effects of nifedipine on myocardial perfusion abnormalities were investigated in 6 patients with left coronary artery disease using a digital angiographic method. Selective left coronary angiograms were digitized on-line into a 256 x 256 pixel matrix, approximately 20 ECG-gated end-diastolic frames being acquired during each coronary injection. After background subtraction, parametric analysis was undertaken, measuring sequential changes in contrast opacification against time. Isochrone maps were derived showing the distribution of times to attainment of peak contrast density throughout the left ventricle (the Tmax image) reflecting myocardial perfusion, and of times to arrival of half peak opacification (the T1/2max image) as an index of coronary flow. At basal heart rate (fixed by pacing) mean Tmax was attained in well supplied myocardium at the 7th cardiac cycle, and at the 9th cardiac cycle in the least perfused territory. Overdrive pacing reduced arrival times by 2-3 cycles, but inhomogeneity persisted. After sublingual nifedipine, contrast arrival was significantly accelerated by a mean of two cardiac cycles in poorly perfused regions, and by one cardiac cycle elsewhere. After nifedipine, overdrive pacing shortened Tmax and T1/2max most markedly in the least supplied territory. Results with this new technique indicate that nifedipine has beneficial effects on regional malperfusion in coronary disease.