Quantitative study of intramyocardial compression in the fibrillating heart.
Extravascular compression inhibits coronary blood flow in fibrillating hearts. Pressure-flow curves from spontaneously fibrillating hearts whose coronary arteries were maximally dilated were examined to see whether this inhibition involves a vascular waterfall mechanism as has been found in the beating heart. Waterfall behavior is indicated when pressure-flow curves are linear and experience a zero-flow intercept at pressures greater than venous pressure. Regional pressure-flow curves revealed a zero flow intercept of 28.4 mmHg for the inner quarter of the left ventricle, indicating that compression is quite high in that region. A zero-pressure intercept of only 15.1 was found at the outer quarter, which was not significantly different from venous pressure. We conclude that the spontaneously fibrillating heart experiences a gradient of compression falling from 28 mmHg at the subendocardium to near zero at the subepicardium.
D000818:Animals; D003326:Coronary Circulation; D004285:Dogs; D004699:Endocardium; D005260:Female; D008297:Male; D011312:Pressure; D014693:Ventricular Fibrillation / Q000503:physiopathology*