Deep Dive: Cardiovascular Physiology-Core Principles: Left Ventricle Systolic Function

Video Transcription

Video Summary

In this video, James Fang discusses left ventricular systolic function. He explains that systolic function refers to the contraction of the myocardium during the isovolemic and ejection phases of the cardiac cycle. Systolic function is determined by factors such as contractility, preload (Frank-Starling mechanism), and afterload. Contractility is the ability of the myocardium to contract independently of load. Contractility is influenced by factors such as heart rate, afterload, and the adrenergic nervous system. Preload refers to the initial stretch of the myocardium before contraction, and it affects ventricular performance. Afterload refers to the forces opposing ventricular ejection and includes factors such as aortic compliance and systemic vascular resistance. Measurement of systolic function is commonly done using ejection fraction, which is the ratio of stroke volume to end-diastolic volume, but it has limitations. An alternative method is global longitudinal strain, which measures ventricular longitudinal shortening independent of volumes and provides insights into subtle systolic dysfunction.

Asset Caption

James Fang, MD

Keywords

left ventricular systolic function

contractility

preload

afterload

ejection fraction

global longitudinal strain

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