Regurgitant fraction is the percentage of blood that regurgitates

Regurgitation (circulation)

Regurgitation is blood flow in the opposite direction from normal, as the backward flowing of blood into the heart or between heart chambers. Can be categorized by:...

 back through the aortic valve

Aortic valve

The aortic valve is one of the valves of the heart. It is normally tricuspid , although in 1% of the population it is found to be congenitally bicuspid . It lies between the left ventricle and the aorta....

 to the left ventricle

Left ventricle

The left ventricle is one of four chambers in the human heart. It receives oxygenated blood from the left atrium via the mitral valve, and pumps it into the aorta via the aortic valve.-Shape:...

 due to aortic insufficiency

Aortic insufficiency

Aortic insufficiency , also known as aortic regurgitation , is the leaking of the aortic valve of the heart that causes blood to flow in the reverse direction during ventricular diastole, from the aorta into the left ventricle....

, or through the mitral valve

Mitral valve

The mitral valve is a dual-flap valve in the heart that lies between the left atrium and the left ventricle...

 to the atrium due to mitral insufficiency. It is measured as the amount of blood regurgitated into a cardiac chamber divided by the stroke volume

Stroke volume

In cardiovascular physiology, stroke volume is the volume of blood pumped from one ventricle of the heart with each beat. SV is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood in the ventricle at the end of a beat from the volume...

.

This fraction affords a quantitative measure of the severity of the valvular lesion. Normally, no blood regurgitates, so the regurgitant fraction is zero. In patients with severe valvular lesions, regurgitant fraction can approach 80%.