Topic
Cardiac cycle
About: Cardiac cycle is a research topic. Over the lifetime, 3290 publications have been published within this topic receiving 96159 citations.
Papers published on a yearly basis
Papers
More filters
TL;DR: In the presence of an intact pericardium, atrial systole shifts the stroke volume-enddiastolic pressure relation because it shifts the end-diastolics pressure-diameter relation and it improves left ventricular performance by increasing preload.
Abstract: The influence of atrial systole on the left ventricular function curve (stroke volume vs end-diastolic pressure or end-diastolic diameter) and on the left ventricular end-diastolic pressure diameter relation was studied in nine anesthetized, open-chest dogs whose atrioventricular (AV) node had been completely blocked. Measurements were made during volume loading with the pericardium closed and opened and during alternate AV sequential pacing (to permit atrial contribution to ventricular filling) and AV simultaneous pacing (to prevent atrial contribution). When the pericardium was closed, withdrawal of the atrial contribution shifted the stroke-volume end-diastolic pressure relation downward, but did not shift the stroke volume-end-diastolic diameter relation, i.e., it reduced stroke volume for a given end-diastolic pressure according to a reduction in end-diastolic volume. The downward shift of the stroke volume-end-diastolic pressure relation was caused by an upward shift of the end-diastolic pressure-diameter relation, which, for a given end-diastolic pressure, resulted in a smaller end-diastolic diameter and, thus, in a smaller stroke volume. The reason for the upward shift in the end-diastolic pressure-diameter relation was that the atrium remained full and thus increased pericardial pressure by increasing pericardial volume. Opening the pericardium shifted the end-diastolic pressure-diameter relation downward and to the right, shifted the stroke volume-end-diastolic diameter relation upward and abolished the effect of withdrawal of the atrial contribution on these curves. We conclude that in the presence of an intact pericardium, atrial systole shifts the stroke volume-end-diastolic pressure relation because it shifts the end-diastolic pressure-diameter relation and it improves left ventricular performance by increasing preload.
119 citations
TL;DR: The hemodynamic parameters of normal hemodynamic function during early embryonic development are defined: blood flow increases geometrically with each embryo stage but remains constant when normalized for embryo weight, vascular resistance and cardiac work increases in proportion to embryo weight.
Abstract: We report the hemodynamic parameters of stage 18, 21, 24, and 27 chick embryos (from 3 to 5 days of incubation). Dorsal aortic blood velocity and mean vitelline artery blood pressure are measured with a 20 MHz pulsed-Doppler meter and servo-null pressure system respectively. We also measure heart rate, dorsal aortic diameter and embryo weight of each developmental stage. From these data, we calculate mean dorsal aortic blood flow, mean dorsal aortic blood flow per cardiac cycle, mean dorsal aortic blood flow per milligram embryo weight, vascular resistance and cardiac work. Blood flow increases geometrically with each embryo stage but remains constant when normalized for embryo weight. Mean arterial pressure increases linearly and vascular resistance decreases geometrically. Cardiac work increases in proportion to embryo weight. These results define the parameters of normal hemodynamic function during early embryonic development.
118 citations
TL;DR: The severity of heart failure and its prognosis are more closely related to the degree of diastsolic filling abnormalities than the ejection fraction, which underscores the importance of understanding the mechanisms of diastolic abnormalities in heart failure.
118 citations
TL;DR: Open chest three-dimensional echocardiography provides a powerful tool for the quantitative physiologic investigation of the left ventricle and permits the analysis of global and regional volumetric and myocardial thickness changes throughout the cardiac cycle.
116 citations
TL;DR: This technique demonstrates that extraparenchymal pulmonary vein flow is dependent on left atrial pressure events and has major potential applications in patients who are prone to develop pulmonary vein obstruction.
116 citations