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A number of reports have been published in which permanent ischemic sequelae occurred even in the presence of a normal Allen's test. [6] [7] In addition, the results of Allen's tests do not appear to correlate with distal blood flow as demonstrated by fluorescein dye injections. [8] [9]
The instantaneous wave-free ratio (iFR, sometimes referred to as the instant wave-free ratio or instant flow reserve) is a diagnostic tool used to assess whether a stenosis is causing a limitation of blood flow in coronary arteries with subsequent ischemia. iFR is performed during cardiac catheterisation (angiography) using invasive coronary pressure wires which are placed in the coronary ...
In "antegrade" flow, the blood flows according to the normal flow within the circulatory system (e.g. veins flow towards the heart while arteries flows away from the heart). In "retrograde" flow, the flow would reverse (e.g. veins flow away from heart or arteries flow towards the heart). However, "retrograde" flow can be both abnormal or normal.
The normal physiological blood flow is antegrade, flowing from the periphery towards the heart, so evidence of an opposite, retrograde flow might indicate a pathology. The presence of a reflux is likewise of note; a reflux, when not isolated in a vein (as simply retrograde), means that the blood flow is bi-directional where once the flow had ...
Fractional flow reserve (FFR) is a diagnostic technique used in coronary catheterization.FFR measures pressure differences across a coronary artery stenosis (narrowing, usually due to atherosclerosis) to determine the likelihood that the stenosis impedes oxygen delivery to the heart muscle (myocardial ischemia).
White blood cells, carried to the area by the newly returning blood, release a host of inflammatory factors such as interleukins as well as free radicals in response to tissue damage. [2] The restored blood flow reintroduces oxygen within cells that damages cellular proteins, DNA, and the plasma membrane. Damage to the cell's membrane may in ...
Blood viscosity is a measure of the resistance of blood to flow. It can also be described as the thickness and stickiness of blood. This biophysical property makes it a critical determinant of friction against the vessel walls, the rate of venous return, the work required for the heart to pump blood, and how much oxygen is transported to tissues and organs.
The normal oxygen tension in the foot is approximately 60 mmHg, and the normal chest/foot ratio is approximately 0.9. [2] Many factors can limit the accuracy of the test including edema, temperature, inflammation, medications, and stress. In addition for the measurement to be normal, all parts of the oxygenation pathway must be functioning: the ...