The effect of graded coronary stenosis on myocardial blood flow and left ventricular wall motion.

The effect of graded coronary stenosis on resting regional myocardial flow and left ventricular (LV) wall motion was studied in 18 anesthetized dogs. The left circumflex coronaary artery (LC) was constricted. The degree of LC stenosis and the changes in LV wall motion were determined by cineangiography of the coronary artery and LV. Regional myocardial flow was determined by tracer microspheres (TM), labeled with two different isotopes, Sr85, Sc46 or Ce141. The first TM1 and the second TM2 were infused after LC stenosis, and during a temporary complete LC occlusion respectively. Resting flow in areas with 70% stenosis was reduced, with a greater reduction of subendocardium and posterior papillary muscle, but minimum impairment of LV wall motion. No ST elevation was found. Animals with 80--90% stenosis showed a marked reduction of flow and wall motion, a significant ST-elevation and a delayed antegrade run-off in coronary arteriography.