Vascular resistance recent results showing the sheath flow surrounding the plug flow in a vessel, the sheath flow size is not neglectible in the real blood flow velocity profile in a vessel. The velocity profile is directly linked to flow resistance in a vessel. The viscosity variations, according to Thurston, are also balanced by the sheath flow size around the plug flow. The secondary regulators of vascular resistance, after vessel radius, is the sheath flow size and its viscosity. Thurston, as well, shows that the resistance R is constant, where, for a defined vessel radius, the value η(δ)/δ is constant in the
Coronary flow reserve Coronary flow reserve Coronary flow reserve (CFR) is the maximum increase in blood flow through the coronary arteries above the normal resting volume. Its measurement is often used in medicine to assist in the treatment of conditions affecting the coronary arteries and to determine the efficacy of treatments used. When demand for oxygen in the myocardium is increased, the vascular resistance of the coronary arteries has the ability to reduce, and this can increase the volume of blood passing through the blood vessels. This reduction occurs because the arteries dilate, which causes an increase in the diameter of the lumen.