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MITRAL STENOSIS (MS)

ETIOLOGY

Most commonly rheumatic, though history of acute rheumatic fever is now uncommon; rare causes include congenital MS and severe calcification of the mitral annulus with extension onto the leaflets.

HISTORY

Symptoms most commonly begin in the fourth decade, but MS often causes severe disability at earlier ages in developing nations. Principal symptoms are dyspnea and cough precipitated by exertion, excitement, fever, anemia, tachycardia, pregnancy, sexual intercourse, and thyrotoxicosis.

PHYSICAL EXAMINATION

Right ventricular lift; palpable S1; opening snap (OS) follows A2 by 0.05–0.12 s; OS–A2 interval inversely proportional to severity of obstruction. Diastolic rumbling murmur, best heard at apex in left lateral decubitus position, with presystolic accentuation when in sinus rhythm. Duration of murmur correlates with severity of obstruction.

COMPLICATIONS

Hemoptysis, pulmonary embolism, respiratory infections, systemic embolization; endocarditis is uncommon in pure MS.

ECG

Typically shows atrial fibrillation (AF) or left atrial (LA) enlargement when sinus rhythm is present. Right-axis deviation and RV hypertrophy in the presence of pulmonary hypertension.

CXR

LA and RV enlargement, pulmonary artery prominence, and Kerley B lines.

ECHOCARDIOGRAM

Shows reduced separation, thickening and calcification of mitral leaflets and subvalvular apparatus, LA enlargement. Doppler assessment provides estimation of transvalvular peak and mean gradients, mitral valve area, and degree of pulmonary hypertension (Chap. 114).

TREATMENT

TREATMENT Mitral Stenosis

At-risk pts should receive prophylaxis for recurrent rheumatic fever (penicillin V 250–500 mg PO bid or benzathine penicillin G 1–2 M units IM monthly) (see Fig. 116-1). For dyspnea, prescribe sodium restriction and oral diuretic therapy; beta blockers, rate-limiting calcium channel antagonists (i.e., verapamil or diltiazem), or digoxin are used to slow ventricular rate in AF. Warfarin (with target INR 2.0–3.0) for pts with AF or history of thromboembolism (direct acting oral anticoagulants [DOACs, e.g., apixaban, rivaroxaban, dabigatran] are not approved for pts with rheumatic MS). For AF of recent onset, consider conversion (chemical or electrical) to sinus rhythm, ideally after ≥3 weeks of anticoagulation. Mitral valvotomy in the presence of symptoms and mitral orifice ≤∼1.5 cm2. In uncomplicated MS, percutaneous balloon valvuloplasty is the procedure of choice; if not feasible, then open surgical valvotomy (Fig. 116-1).

FIGURE 116-1

Management of rheumatic mitral stenosis. MR, mitral regurgitation; MS, mitral stenosis; MVA, mitral valve area; MVR, mitral valve surgery (repair or replacement); NYHA, New York Heart Association; PCWP, pulmonary capillary wedge pressure; PMBC, percutaneous mitral balloon commissurotomy; T½, pressure half-time. (Adapted from Nishimura RA et al: 2014 AHA/ACC Guideline for the Management of Patients with Valvular Heart Disease. J Am Coll Cardiol 63:e57, 2014.)

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