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An increase in contractility tends to increase stroke volume and thus a secondary increase in preload. An increase in preload results in an increased force of contraction by Starling's law of the heart; this does not require a change in contractility. An increase in afterload will increase contractility (through the Anrep effect). [4]
An increase in contractility is manifested as an increase in dP/dt max during isovolumic contraction. However, dP/dt max is also influenced by preload, afterload, heart rate, and myocardial hypertrophy. Hence, the relationship between ventricular end-diastolic volume and dP/dt is a more accurate index of contractility than dP/dt alone.
End-systolic volume (ESV) is the volume of blood in a ventricle at the end of contraction, or systole, and the beginning of filling, or diastole. ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle. The main factors that affect the end-systolic volume are afterload and the contractility of the heart.
An ejection fraction (EF) is the volumetric fraction (or portion of the total) of fluid (usually blood) ejected from a chamber (usually the heart) with each contraction (or heartbeat). It can refer to the cardiac atrium , [ 1 ] cardiac ventricle , [ 2 ] gall bladder, [ 3 ] or leg veins, [ 4 ] although if unspecified it usually refers to the ...
Major factors influencing cardiac output – heart rate and stroke volume, both of which are variable. [1]In cardiac physiology, cardiac output (CO), also known as heart output and often denoted by the symbols , ˙, or ˙, [2] is the volumetric flow rate of the heart's pumping output: that is, the volume of blood being pumped by a single ventricle of the heart, per unit time (usually measured ...
In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood in the ventricle at the end of a beat (called end-systolic volume [note 1]) from the volume of blood just prior to the beat (called end-diastolic volume).
Contractility refers to the ability for self-contraction, especially of the muscles or similar active biological tissue Contractile ring in cytokinesis;
There are different ways to measure the regional function of the wall. It has been proposed to measure the speed of the LV wall motion, the thickening of the wall, or other changes in the shape of small regions of the wall as it contracts and relaxes. The latter is best measured using the mechanical quantity called “strain."