Acquired Mitral Stenosis Clinical Presentation

Patients with mild mitral stenosis (MS) may deny all symptoms. They may provide a history consistent with acute rheumatic fever; however, in a given patient, an inverse relationship between the severity of rheumatic heart disease and the severity of rheumatic arthritis is often observed.

The most prominent symptom of severe MS is dyspnea. This results from pulmonary congestion. Patients with severe MS may also experience orthopnea as well as significant exercise limitation.

MS due to rheumatic heart disease rarely occurs in childhood in the United States. When it does occur, the history generally reveals the insidious onset of exercise limitation. These patients may present with certain signs.

• Pulmonary congestion is evidenced by increasing severity of dyspnea (depending on the degree of MS), ranging from dyspnea only during exercise to paroxysmal nocturnal dyspnea, orthopnea, or even symptoms related to frank pulmonary edema.
• Dyspnea may be precipitated or worsened by an increase in blood flow across the stenotic mitral valve (eg, pregnancy, exercise) or a reduction in diastolic filling time because of increased heart rate (eg, emotional stress, fever, respiratory infection, atrial fibrillation with rapid ventricular rate).
• Signs of right heart failure, including peripheral edema and fatigue, may appear late.
• Approximately 30-40% of patients with MS eventually develop atrial fibrillation. This rarely occurs in the pediatric age group. Atrial fibrillation may cause the following:

  • Loss of the atrial kick to the LV filling that may further diminish cardiac output
  • Thromboembolic events, occurring in 10-20% of patients with MS, approximately 75% of which cause stroke
  • Infective endocarditis, which should be suspected if embolization occurs during sinus rhythm
• Hemoptysis may be caused by rupture of dilated bronchial veins, and pink frothy sputum may be a manifestation of pulmonary edema. Both are associated with endstage and severe MS.
• Chest pain, possibly related to RV hypertension, occurs in approximately 15% of patients with MS.
• Rarely, dysphagia may occur from compression of the esophagus by an enlarged left atrium. Hoarseness may occur if the enlarged left atrium impinges on the recurrent laryngeal nerve.

Physical examination findings vary according to the severity of MS.

• Mild-to-moderate MS

  • Normal peripheral pulses and good perfusion
  • Loud S₁ because of abrupt closure of a stenotic, but still pliable, mitral valve
  • Long A₂ to opening snap interval: In mild MS, left atrial pressure is mildly increased; as a result, the mitral valve opens at a more normal interval after closure of the aortic valve (A₂).
  • Diastolic murmur: The diastolic murmur of MS begins at the time of mitral valve opening and accentuates following atrial contraction (presystolic accentuation) as long as the patient is in sinus rhythm. The murmur is low frequency and rumbling in quality. In mild MS, the mid diastolic murmur may be difficult to hear. As MS becomes more severe, murmur duration increases, and, to some extent, intensity also increases.
  • No S₃
  • Pulmonic component of S₂: The pulmonic component of the second heart sound increases in intensity in direct proportion to elevation of left atrial (and, consequently, pulmonary artery) pressure. Similarly, the A₂ -P₂ splitting interval narrows as pulmonary artery pressure increases.
• Severe MS

  • Diminished peripheral perfusion and pulses because of decreased cardiac output
  • Palpation of an RV impulse (enlarged RV) because of pulmonary hypertension
  • Soft S₁ because of decreased mobility of the mitral leaflets as they become more thickened and/or calcified: Decreased cardiac output with severe stenosis also decreases the intensity of the S₁, particularly with a faster heart rate.
  • Shorter A₂ to opening snap interval: As left atrial pressure increases, the mitral valve opens earlier in relation to aortic valve closure (S₂).
  • Diastolic rumble: A long, low-frequency diastolic rumble with presystolic accentuation is best heard at the apex. Murmur intensity decreases as cardiac output decreases.
  • Increased intensity of pulmonic component of S₂ (P₂) secondary to pulmonary hypertension
  • RV S₃ or RV S₄: RV S₃ or RV S₄ may occur; however, an RV S₃ is rare in the presence of tricuspid valve regurgitation.
  • Systolic murmur: A systolic murmur of tricuspid regurgitation may occur as right ventricular function deteriorates. This murmur is best heard at the lower left sternal edge. It accentuates with inspiration.
  • Diastolic murmur: A high-frequency early diastolic murmur of pulmonic valve regurgitation may be heard immediately following an accentuated P₂. Eponymously called the Graham Steell murmur, this finding reflects severe pulmonary hypertension.

In order for MS to develop from acute rheumatic fever, two conditions are required: infection with group A streptococcus and genetic susceptibility to develop valvular disease.

• Epidemiology: Acute rheumatic fever is an immunologic disease that occurs in 0.3-3% of patients as a complication of group A streptococcal infection of the pharynx. It is very rarely observed after group A streptococcal infection of the skin.
• Inheritance: A distinct genetic susceptibility to rheumatic fever is observed, with studies suggesting a single recessive gene. Other studies identified an allotypic marker on B lymphocytes, present in almost all patients with rheumatic fever but in only a small proportion of healthy controls. Investigations also revealed a significantly higher percentage of certain human leukocyte antigens (HLAs) in patients with rheumatic fever than in controls.
• Risk factors: Family history of rheumatic fever is a risk factor and is consistent with genetic factors. Poverty, poor hygiene, and medical deprivation are predisposing factors for rheumatic fever, probably because they identify a population less likely to obtain proper treatment of streptococcal pharyngitis.
• Acquired MS: Acquired MS results from long-term damage to the mitral valve and its supporting structures.

  • In rheumatic heart disease, autoimmune responses occur secondary to beta-hemolytic streptococci group A antigens. Damage to the heart is postulated to result from antiheart antibodies (eg, gamma globulins, complement C3). An initial pancarditis, which involves the pericardium, epicardium, myocardium, and endocardium, may result in long-term changes with damage along the free edges of a heart valve with deposition of platelets that result in inflammation plus subsequent fibrosis, and, finally, contracture of the valve leaflets. If inflammation is severe, cusps are damaged, and valvar insufficiency ensues. The mitral and aortic valves are the most commonly affected.
  • Poststreptococcal reactive arthritis (PSRA) is an arthritic condition that does not fulfill the Jones criteria for acute rheumatic fever. Therefore, patients have elevated acute phase reactants and serologic evidence of recent group A streptococcal infection; however, arthritis is additive rather than migratory, responds poorly to salicylates and nonsteroidals, and persists for a mean of 2 months. PSRA is associated with the HLA-DRB1*01.^[5] As many as 6% of patients with PSRA develop mitral valve disease.
  • Systemic lupus erythematosus may induce pericarditis, myocarditis, and endocarditis (ie, Libman-Sacks endocarditis), which consists of verrucous vegetations on the valves composed of proliferating and degenerating cells, fibrin, and occasional hematoxylin body deposits. The most commonly affected valve is the mitral valve, but these lesions rarely cause either valvar insufficiency or stenosis.
  • Amyloidosis, which is rare in childhood, is secondary to an underlying inflammatory process. Extracellular deposits of insoluble proteins (amyloid) in the myocardium, pericardium, and conducting tissue produce a restrictive or hypertrophic cardiomyopathy. When amyloid deposits in the valves, valvar insufficiency and/or stenosis can ensue.
  • Postsurgical acquired MS, such as MS occurring after mitral valve annuloplasty for severe mitral valve regurgitation, is caused by fibrosis along the annulus. These patients may require mitral valve replacement with a prosthetic mitral valve if the MS is severe enough to cause symptoms (eg, pulmonary edema). Improper repair of the cleft mitral valve in an endocardial cushion defect can also result in MS.