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The experiments were concerned with the coronary capillary circulation of the left atrium in the potassium chloride arrested cat heart, using transillumination. Capillary red cell velocity was measured using cinematography and color films (16 mm 24 frames/s) and frame to frame analysis of red cell progression. Optical magnification on the film was from 20 to 30 times. Capillaries were visualized as lying on either side of the muscle fiber. Numerous intercapillary anastomoses which communicate through interconnecting loops of varying lengths were visualized. Capillary diameter varies from 4 to 8 μm. Constancy of capillary red cell velocity was present at from 75 to 210 mmHg. With increasing perfusion pressure, the number of capillaries with discernible red cell movement increased as perfusion pressure rose (recruitment). In some capillaries, abrupt and extreme changes in red cell velocity were observed at the same perfusion pressure. About 10 to 30% of all capillaries showed counter-current flow in adjacent capillaries.

Stasis in the coronary microcirculation has been proposed as a major factor leading to left ventricular subendocardial hemorrhagic necrosis and low-output syndrome after open-heart operations. In order to test this proposition, anoxic arrest of 60 to 75 minutes' duration was produced in two groups of experimental animals. The control animals all died intraoperatively, while all those whose left coronary artery was flushed with a physiological solution during the experiment survived the procedure without significant hemodynamic or pathological changes. From this and a review of the literature, proposals are advanced on the cause of hemorrhagic necrosis and the protection afforded by coronary flushing during anoxic cardioplegia.

Excerpt Experiments were carried out by high-speed cinematography (400 frames per second) using transillumination of the left atrium of the cat heart. Red cell velocity in capillaries was determine...

Impaired left ventricular (LV) myocardial twisting indicate the presence of subclinical LV dysfunction. Blood pressure, arterial stiffness, LV mass, and impaired coronary microcirculation determine LV function in hypertensives. We investigated the effects antihypertensive treatment on deformation

Intracoronary CDCs increase myocyte proliferation and improve regional function in hibernating myocardium (HM) but their effects on the coronary microcirculation are unknown. Accordingly, swine with collateral–dependent HM from a chronic LAD occlusion (n=12) were studied 4–months after