{V_{mitral \times 100\%</math>

where V<sub>mitral</sub> and V<sub>aortic</sub> are, respectively, the volumes of blood that flow forward through the mitral valve and aortic valve during a cardiac cycle.

Methods that have been used to assess the regurgitant fraction in mitral regurgitation include echocardiography, cardiac catheterization, fast CT scan, and cardiac MRI. The echocardiographic technique to measure the regurgitant fraction is to determine the forward flow through the mitral valve (from the left atrium to the left ventricle) during ventricular diastole, and comparing it with the flow out of the left ventricle through the aortic valve in ventricular systole. This method assumes that the aortic valve does not have aortic insufficiency. Another way to quantify the degree of MR is to determine the area of the regurgitant flow at the level of the valve. This is known as the regurgitant orifice area and correlates with the size of the defect in the mitral valve. One particular echocardiographic technique used to measure the orifice area is measurement of the proximal isovelocity surface area (PISA). The flaw of using PISA to determine the mitral valve regurgitant orifice area is that it measures the flow at one moment in time in the cardiac cycle, which may not reflect the average performance of the regurgitant jet.

thumb|PISA method for quantification of mitral regurgitation

{| class="wikitable" style="margin:auto"

|+ Determination of the degree of mitral regurgitation

|-

!Grade

! Degree of mitral regurgitation

! Regurgitant fraction

! width="100px" | Regurgitant Orifice area

|-

|1

|Mild || < 20 percent || rowspan="3" |

|-

|2

|Moderate || 20–40 percent

|-

|3

|Moderate to severe || 40–60 percent

|-

|4

|Severe || > 60 percent || > 0.4&nbsp;cm<sup>2</sup>

|}

Treatment

The treatment of MR depends on the acuteness of the disease and whether there are associated signs of hemodynamic compromise. In general, medical therapy is non-curative and is used for mild-to-moderate regurgitation or in patients unable to tolerate surgery.

Individuals with chronic MR can be treated with vasodilators as well to decrease afterload. The current guidelines for treatment of MR limit the use of vasodilators to individuals with hypertension, however. Any hypertension is treated aggressively,

Indications for surgery for chronic MR include signs of left ventricular dysfunction with ejection fraction less than 60%, severe pulmonary hypertension with pulmonary artery systolic pressure greater than 50 mmHg at rest or 60 mmHg during activity, and new-onset atrial fibrillation.

{| class="wikitable" style="margin:auto"

|+ Indications for surgery for chronic MR

! Symptoms

! LV EF

! LVESD

|-

|NYHA II || > 30 percent || < 55&nbsp;mm

|-

|NYHA III-IV || < 30 percent || > 55&nbsp;mm

|-

|Asymptomatic || 30–60 percent || ≥ 40&nbsp;mm

|-

|Asymptomatic with pulmonary hypertension || colspan="2" | LV EF > 60 percent and pulmonary artery systolic pressure >50-60&nbsp;mmHg

|-

|Asymptomatic and chance for a repair without residual MR is >90% || > 60 percent || < 40&nbsp;mm

|}

Epidemiology

Significant mitral valve regurgitation has a prevalence of approximately 2% of the population, affecting males and females equally. It is one of the two most common valvular heart diseases in the elderly, and the commonest type of valvular heart disease in low and middle income countries.

See also

  • Aortic regurgitation
  • Pulmonary insufficiency
  • Tricuspid regurgitation

References