Topic
Cardiac cycle
About: Cardiac cycle is a research topic. Over the lifetime, 3290 publications have been published within this topic receiving 96159 citations.
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TL;DR: The lower incidence of return of effective atrial systole on the left side, despite the return of normal atrial excitation, is explained by the more severe left-sided disease.
62 citations
TL;DR: The temporal relationship of flow pulses in the pulmonary artery, capillaries, and veins was investigated in 10 chronic dog preparations with pulsed ultrasonic flowmeters and a nitrous oxide-body plethysmograph for capillary flow.
Abstract: The temporal relationship of flow pulses in the pulmonary artery, capillaries, and veins was investigated in 10 chronic dog preparations with pulsed ultrasonic flowmeters and a nitrous oxide-body plethysmograph for capillary flow. Implanted pressure transducers in the left atrium provided reference to the conventional atrial pulses: A, C, X-descent, V, and Y-descent. Left atrial contraction produced an A-wave pressure transient followed by retrograde flow up the veins. The C-pressure pulse occasionally produced a minimal trough in the venous flow pattern. Early in ventricular systole, X-descent in left atrial pressure preceded a venous flow pulse of modest amplitude, which began prior to the onset of the pulse of capillary flow. On average, right ventricular ejection was followed in 37 msec by the major flow pulse in the capillaries, which in turn was followed 68 msec later by the onset of venous flow. This venous flow pulse was simultaneous with a rise in left atrial pressure, the V-wave. With the onset of diastole, the Y-descent in atrial pressure preceded a major venous flow pulse. With accelerated heart rate, separation of the V and Y venous flow pulses was lost, and a monophasic pulse was found.
62 citations
62 citations
TL;DR: In this article, results of left heart catheterization in two normal individuals and 125 patients with rheumatic heart disease were presented, and the normal pressure curves were described. But no pressure gradients exist across a normal mitral or aortic valve.
62 citations
Patent•
15 Jun 2006TL;DR: In this article, an atrial-based pacing protocol was proposed to promote the intrinsic conduction of the atrial ventricular activity. But, the pacing protocol is not suitable for patients with a high likelihood of a ventricular sensed event.
Abstract: An atrial based pacing protocol promotes intrinsic conduction. An entire cardiac cycle is monitored for ventricular activity and permitted to lapse with ventricular activity. Ventricular pacing is available in a cardiac cycle immediately subsequent to such a skipped beat. When monitoring for intrinsic ventricular events, an event is expected within a given window. If no such event is detected, the cardiac cycle in truncated, leading to a shorter cycle that is devoid of ventricular activity. The subsequent cycle has a high likelihood of a ventricular sensed event and a greater than normal AV interval is provided prior to pacing.
62 citations