miTRal STenOsiS

Mitral stenosis is characterized by restriction of blood flow from the left atrium (LA) to the left ventricle (LV) as a result of a narrowed mitral passage. It is an acquired valvular defect; it is usually a consequence of rheumatic heart disease, though cases of congenital mitral stenosis are occasionally encountered. Extensive mitral annular calcification (MAC) may result in mitral stenosis, particularly in the aged.

Mitral stenosis is seen more often in women than in men, and it generally develops at an earlier age in developing countries than in Western societies. In the latter, the incidence of rheumatic fever has declined precipitously over the past 4 decades.

Patients with mitral stenosis usually remain symptom-free for years. After the mitral orifice is reduced to one third of its normal size, symptoms typical of left-sided heart failure develop, such as dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea. Right ventricular (RV) failure gradually ensues, causing ascites and edema.Asymptomatic individuals with sinus rhythm on ECG need no treatment.

Symptoms of dyspnea and orthopnea improve with the use of diuretics. As symptoms worsen and pulmonary hypertension occurs, mechanical correction of the stenosis, rather than medical therapy, becomes necessary. These surgical options, which include valvuloplasty and mitral valve replacement, have changed the natural history of mitral stenosis, and terminally bedridden patients with mitral facies, cardiac cachexia, and end-stage congestive heart failure (CHF) are no longer encountered in everyday clinical practice.

Causes of mitral stenosis

• Rheumatic heart disease
• MAC, degenerative
• Congenital conditions
  • Thickened chordae
  • Single papillary muscle
• Miscellaneous conditions
  • Carcinoid
  • Lupus
  • Rheumatoid arthritis
  • Mucopolysaccharidosis (Hurler syndrome)
  • Coxsackie infection
  • Amyloidosis
  • Methysergide

Differential diagnoses

• Atrial myxoma
• Ball-valve thrombus
• Cor triatriatum
• Submitral ring or web

Mitral stenosis with atrial fibrillation

Patients with mitral stenosis and atrial fibrillation frequently present with decompensated congestive heart failure (CHF). The rapid ventricular rate shortens the diastolic filling time to a period insufficient to allow the LA to empty. As a consequence, the LA pressure rises and the forward cardiac output decreases.

Congenital mitral stenosis

Symptoms of mitral stenosis usually appear within the first 2 years of life. Infants have delayed development and breathlessness, caused by heart failure. Cyanosis and pallor may be noted. The heart is enlarged as a result of dilatation and hypertrophy of the RV and LA. Rumbling apical diastolic murmur is usually audible, followed by a loud first sound. The OS is usually absent.

Preferred Examination

Echocardiography, especially Doppler echocardiography, is the procedure of choice for evaluating the degree of mitral stenosis; in most of the patients, echocardiography may be adequate for the planning of therapeutic interventions.