Ventricular filling pressure as a determinant of coronary blood flow during ischemia.

The role of ventricular filling pressure (VFP) as a determinant of coronary blood flow (CBF) in the acutely ischemic ventricle was examined in the open-chest dog under conditions of a reduced, constant coronary artery pressure and an unstable VFP. Blood delivery to different layers of the ventricle and ischemic metabolic changes occurring in these layers were also determined and compared with appropriate control data. A close, inverse, linear relationship between VFP and CBF was found in animals exhibiting a progressive rise in VFP from 6 +/- 0 to 25 +/- 1 mmHg (r = 0.99). A lower endocardial-to-epicardial ratio of delivered blood and a steeper transmural gradient in ischemic metabolic changes were noted in these animals compared with similarly prepared animals exhibiting a stable VFP. The findings demonstrate the importance of VFP as a determinant of CBF during ischemia, and they lend support to the concept that blood flow in the ischemic ventricle is regulated by a preload-dependent transmural gradient in coronary driving pressure.