Mitral Regurgitation

Key Features

Essentials of Diagnosis

• May be asymptomatic for years (or for life)

• Severe mitral regurgitation may cause left-sided heart failure and lead to pulmonary hypertension and right-sided heart failure

• Pansystolic murmur at the apex, radiating into the axilla; associated with S₃ when regurgitant volume is great

• ECG shows left atrial (LA) abnormality or atrial fibrillation and left ventricular hypertrophy (LVH); radiograph shows LA and left ventricular (LV) enlargement

General Considerations

• Some clinicians use the Carpentier classification regarding mobility of the mitral leaflets

  • Type I is normal

  • Type II reflects increased leaflet motion (as in prolapse or chordal rupture)

  • Type III is related to papillary muscle displacement

    • Type IIIa reflects restricted mitral leaflets in both systole and diastole

    • Type IIIb reflects restricted motion in systole only

• Mitral regurgitation increases preload and reduces afterload, resulting in an enlarged LV with an increased ejection fraction (EF)

• Over time, the stress of the volume overload reduces myocardial contractile function; when this occurs, there is a drop in EF and a rise in end-systolic volume

Clinical Findings

• Characterized by a pansystolic murmur maximal at the apex, radiating to the axilla and occasionally to the base

  • The murmur does not change in intensity after a premature beat because the LV to LA gradient is unaffected

  • The murmur intensity may be modest due to little difference between the LA and LV systolic pressures during ventricular systole

  • When the murmur is due to mitral valve prolapse, it tends to radiate anteriorly in the presence of posterior leaflet prolapse and posteriorly when the prolapse is primarily of the anterior leaflet

• In addition, a hyperdynamic LV impulse and a brisk carotid upstroke may be present along with a prominent third heart sound due to the increased volume returning to the LV in early diastole

• In acute cases,

  • The LA size is not large

  • The LA pressure rises abruptly, leading to pulmonary edema if severe

• In chronic cases,

  • The LA enlarges progressively

  • The increased volume can be handled without a major rise in the LA pressure

  • The pressure in pulmonary veins and capillaries may rise only during exertion

  • Exertional dyspnea and fatigue progress gradually over many years

Diagnosis

• Echocardiography/Doppler

  • Findings may demonstrate the

    • Underlying pathologic process (rheumatic, calcific, prolapse, flail leaflet, endocarditis, cardiomyopathy)

    • LV size and function

    • LA size

    • PA pressure

    • RV function

  • The valvular heart disease guidelines provide details of the classification and measures of severity for primary and secondary mitral valve regurgitation

• Transesophageal echocardiography

  • May help reveal the cause of regurgitation

  • Is especially useful in patients who have had mitral valve replacement, in whom endocarditis is suspected, and in identifying candidates for valvular repair

  • Echocardiographic dimensions and measures of systolic function are critical in deciding the timing of ...