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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.
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 ...
This gives an LV stroke volume of 3.14 * 24 = 75.40 cc. Divide the LV stroke volume, 75.40 cc by the Aortic Valve VTI, 50 cm and this gives an aortic valve area of 75.40 / 50 = 1.51 cm 2. The weakest aspect of this calculation is the variability in measurement of LVOT area, because it involves squaring the LVOT dimension.
Ejection fraction. 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] ventricle, [ 2] gall bladder, [ 3] or leg veins, [ 4] although if unspecified it usually refers to ...
Velocity Time Integral is a clinical Doppler ultrasound measurement of blood flow, equivalent to the area under the velocity time curve. The product of VTI (cm/stroke) and the cross sectional area of a valve (cm2) yields a stroke volume (cm3/stroke), which can be used to calculate cardiac output. VTI can be performed across the left ventricular ...
The Frank–Starling law is named after the two physiologists, Otto Frank and Ernest Henry Starling. However, neither Frank nor Starling was the first to describe the relationship between the end-diastolic volume and the regulation of cardiac output. [5] The first formulation of the law was theorized by the Italian physiologist Dario Maestrini ...
The Otto cycle is a description of what happens to a gas as it is subjected to changes of pressure, temperature, volume, addition of heat, and removal of heat. The gas that is subjected to those changes is called the system. The system, in this case, is defined to be the fluid (gas) within the cylinder.
In a piston engine, the static compression ratio ( ) is the ratio between the volume of the cylinder and combustion chamber when the piston is at the bottom of its stroke, and the volume of the combustion chamber when the piston is at the top of its stroke. [ 9] It is therefore calculated by the formula [ 10] where. is the displacement volume.