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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 ...
The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known: Amount of marker substance taken up by the organ per unit time; Concentration of marker substance in arterial blood supplying the organ; Concentration of marker substance in venous blood leaving the organ
Often expressed in cm/s. This value is inversely related to the total cross-sectional area of the blood vessel and also differs per cross-section, because in normal condition the blood flow has laminar characteristics. For this reason, the blood flow velocity is the fastest in the middle of the vessel and slowest at the vessel wall.
For example, if systemic venous return is suddenly increased (e.g., changing from upright to supine position), right ventricular preload increases leading to an increase in stroke volume and pulmonary blood flow. The left ventricle experiences an increase in pulmonary venous return, which in turn increases left ventricular preload and stroke ...
This ultimately leads to a reduction in the haemodynamic response and less blood flow in the brain. This reduced cerebral blood flow not only kills neuronal cells because of shortages in oxygen and glucose but it also reduces the brain's ability to remove amyloid beta. In a healthy brain, these protein fragments are broken down and eliminated.
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 the left ...
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.
Coronary flow reserve is used in diagnostics and treatment of patients with conditions such as coronary artery disease and syndrome X. [7] In the treatment of these conditions, vasodilators are used to allow sufficient blood to flow past a stenosis, for example, and the measurement of CFR enables the efficacy of such interventions to be measured.