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An increase in EDV increases the preload on the heart and, through the Frank-Starling mechanism of the heart, ... The right ventricular end-diastolic volume index ...
A blood volume increase would cause a shift along the line to the right, which increases left ventricular end diastolic volume (x axis), and therefore also increases stroke volume (y axis). The Frank–Starling law of the heart (also known as Starling's law and the Frank–Starling mechanism ) represents the relationship between stroke volume ...
In other words, if the end-diastolic volume increases, there is a corresponding increase in stroke volume. The Frank–Starling mechanism can be explained on the basis of preload. As the heart fills with more blood than usual, there is an increase in the load experienced by each myocyte .
Preload can still be approximated by the inexpensive echocardiographic measurement end-diastolic volume or EDV. Preload increases with exercise (slightly), increasing blood volume (as in edema , excessive blood transfusion (overtransfusion), polycythemia ) and neuroendocrine activity (sympathetic tone).
Stroke volume is an important determinant of cardiac output, which is the product of stroke volume and heart rate, and is also used to calculate ejection fraction, which is stroke volume divided by end-diastolic volume. Because stroke volume decreases in certain conditions and disease states, stroke volume itself correlates with cardiac function.
In accordance with the Frank–Starling law of the heart, the myocardium contracts more powerfully as the end-diastolic volume increases. Stretching of the myofibrils in cardiac muscle causes them to contract more powerfully due to a greater number of cross-bridges being formed between the myofibrils within cardiac myocytes. [2]
A reduced stroke volume may occur as a result of a failure of systole, diastole or both. Increased end systolic volume is usually caused by reduced contractility. Decreased end diastolic volume results from impaired ventricular filling; this occurs when the compliance of the ventricle falls (i.e. when the walls stiffen). As the heart works ...
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 ...