Abstract 16619: The Role of Capillary Disorder in Coronary Ischemic Congestive Heart Failure in Rats

Abstract

The aim of present study is to explore the role of capillary disorder in coronary ischemic congestive heart failure (CHF). Methods: CHF was induced in rats by aortic banding plus ischemia/reperfusion followed by aortic de-banding. Coronary arteries were perfused with plastic polymer containing fluorescent dye. Multiple fluorescent images of casted heart sections and scanning electric microscope of coronary vessels were conducted to characterize changes in the heart. Cardiac function was assessed by echocardiography and in vivo hemodynamics. Results: Stenosis was found in all levels of coronary artery in CHF. Coronary vasculature volume and capillary density in remote myocardium were significantly increased in CHF compared with control. This occurred largely in micro-vessels with diameter ≤ 3 μm. Capillaries in CHF had a tortuous structure, while normal capillaries were linear. Capillaries in CHF had inconsistent diameters, with assortments of narrowed and bulged segments. Their surfaces appeared rough, likely indicating endothelial dysfunction in CHF. Segments of main capillaries between bifurcations were significantly shorter in CHF than in control. Transiently increasing preload by injecting 50 μl of 30% NaCl demonstrated that the CHF heart has lower functional reserve; this is likely associated with congestion in coronary microcirculation. Conclusions: Ischemic coronary vascular disorder is not limited to main arteries, but also occurs in arterioles and capillaries. Capillary disorder in CHF included stenosis, deformed structure, proliferation and roughened surfaces, and is perhaps a primary contributor to the energy starvation which leads to reduction of myocyte intrinsic contractility.