Coronary flow reserve (CFR) is the maximum increase in blood flow through the

coronary arteries The coronary arteries are the arterial blood vessels of coronary circulation, which transport oxygenated blood to the heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any other tissue or organ of ...

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.

Overview

When demand for oxygen in the

myocardium Cardiac muscle (also called heart muscle, myocardium, cardiomyocytes and cardiac myocytes) is one of three types of vertebrate muscle tissues, with the other two being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that ...

is increased, the

vascular resistance Vascular resistance is the resistance that must be overcome to push blood through the circulatory system and create flow. The resistance offered by the systemic circulation is known as the systemic vascular resistance (SVR) or may sometimes be ca ...

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 Dilation (or dilatation) may refer to: Physiology or medicine * Cervical dilation, the widening of the cervix in childbirth, miscarriage etc. * Coronary dilation, or coronary reflex * Dilation and curettage, the opening of the cervix and surgic ...

, which causes an increase in the diameter of the lumen. The greatest potential for this change is normally in the branches (

arterioles An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the primar ...

) of the coronary artery that penetrate the myocardium, rather than those on the surface of the heart.

Measurement

Coronary flow reserve can be measured through a variety of methods, including digital subtraction

cineangiography Angiography or arteriography is a medical imaging technique used to visualize the inside, or lumen, of blood vessels and organs of the body, with particular interest in the arteries, veins, and the heart chambers. Modern angiography is perform ...

with

coronary catheterization A coronary catheterization is a minimally invasive procedure to access the coronary circulation and blood filled chambers of the heart using a catheter. It is performed for both diagnostic and interventional (treatment) purposes. Coronary cathet ...

doppler echocardiography Doppler echocardiography is a procedure that uses Doppler ultrasonography to examine the heart. An echocardiogram uses high frequency sound waves to create an image of the heart while the use of Doppler technology allows determination of the spee ...

, and

positron emission tomography Positron emission tomography (PET) is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in Metabolism, metabolic processes, and in other physiological activities including bl ...

(PET).

Medical implications

Coronary flow reserve is used in diagnostics and treatment of patients with conditions such as

coronary artery disease Coronary artery disease (CAD), also called coronary heart disease (CHD), ischemic heart disease (IHD), myocardial ischemia, or simply heart disease, involves the reduction of blood flow to the heart muscle due to build-up of atherosclerotic pla ...

and syndrome X. In the treatment of these conditions,

vasodilator Vasodilation is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. The process is the opposite of vasoconstriction, ...

s are used to allow sufficient blood to flow past a

stenosis A stenosis (from Ancient Greek στενός, "narrow") is an abnormal narrowing in a blood vessel or other tubular organ or structure such as foramina and canals. It is also sometimes called a stricture (as in urethral stricture). ''Stricture'' ...

, for example, and the measurement of CFR enables the efficacy of such interventions to be measured. In patients with

Anderson-Fabry disease Fabry disease, also known as Anderson–Fabry disease, is a rare genetic disease that can affect many parts of the body, including the kidneys, heart, and skin. Fabry disease is one of a group of conditions known as lysosomal storage diseases. T ...

, there is evidence to suggest that CFR can be reduced. When coronary flow reserve is used in medicine, it is often expressed with a numerical value, which is formed by dividing the maximal coronary blood flow by resting blood flow. This allows for an objective view, which can aid diagnosis and treatment.

References

{{DEFAULTSORT:Coronary Flow Reserve Cardiology

Overview

Measurement

Medical implications

See also

References