Physiologic--angiographic correlates of coronary arterial stenoses in resting and intensely vasodilated states

The treatment of ischemic heart disease is dependent upon defining the physiologic significance of coronary arterial stenoses demonstrated on coronary arteriograms. Accordingly, physiologic--angiographic correlates were studied in 12 anesthetized dogs prepared with an electromagnetic flowmeter and micrometer-controlled occluder on the circumflex coronary artery, a pair of sonic crystals in the myocardium within the distribution of the circumflex artery, and a catheter in the thoracic aorta. Measurement of arterial diameters on coronary arteriograms was made to define the minimum percent stenosis that caused: (1) decrease in resting coronary blood flow (CBFr); decline in the peak level of coronary blood flow (CBF) produced by intense vasodilatation induced by intracoronary infusion of ATP (CBFATP); and (3) segmental left ventricular (LV) dysfunction. CBFR decreased at an average stenosis of 80.45 +/- 9.13% (SD) (percent reduction in luminal diameter), while CBFATP declined at a stenosis of 31.83 +/- 5.64%. Segmental LV dysfunction was observed at a stenosis of 85.92 +/- 9.83%. In all dogs, the initial stenosis causing decline in CBFATP was a less than or equal to 40% reduction in luminal diameter. The results of this study indicate that coronary arterial stenoses of 40% or less may be hemodynamically significant under situations of augmented CBF. On the other hand, regional contractile function at rest is preserved up to stenosis in excess of 80%.