The effect of graded coronary flow reduction in the left anterior descending and septal arteries on left ventricular function in the canine heart.

WE quantitatively analyzed the effect of graded left anterior descending and septal coronary flow (LAD + septal flow) reduction on left ventricular function with a left ventricular end-diastolic pressure (LVEDP) of 6 mm Hg and 12 mm Hg. We used an isolated, ejecting, canine heart preparation ( n = 8), the coronary flow of which could be controlled independently of the aortic pressure. We kept the other hemodynamic variables - heart rate, left circumflex coronary flow, right coronary flow and aortic input impendance - constant within their normal physiologic range. We considered this reduction in LAD + septal flow to be analogous to that of the most frequent lesion in ischemic heart disease. There was no plateau in the left ventricular work caused by this reduction of the regional coronary flow. Therefore, the plateau commonly reported in previous studies may be partially a result of the compensatory elevation of LVEDP, which is necessary to maintain the left ventricular work.