Atlas of Pathos Chapter 6

Mitral Valve Prolapse

M itral valve prolapse is also called systolic click-murmur syn- drome and floppy mitral valve syndrome . It’s probably a con- genital abnormality. Causes • Autosomal dominant inheritance • Inherited connective tissue disorders, such as Marfan syndrome, Ehlers-Danlos syndrome, and osteogenesis imperfecta • Genetic or environmental interruption of valve develop- ment during week 5 or 6 of gestation Pathophysiology The cusps of the mitral valve are enlarged, thickened, and scal- loped, possibly secondary to collagen abnormalities. The chor- dae tendineae may be longer than usual, allowing the cusps to stretch upward.

Clinical tip The high incidence of mitral valve prolapse (3% to 8% of adults) suggests that it may be a normal variant. It occurs more often in women than in men. Although severe sequelae may occur (such as ruptured chordae tendineae, ventricular fail- ure, emboli, bacterial endocarditis, and sudden death), mortality and morbidity are low. Most affected persons experience no physical limita- tions. The psychological effects of the diagnosis may be more disabling than the disease process itself.

DiagnosticTest Results • Echocardiography reveals mitral valve prolapse with or with- out mitral insufficiency. • ECG (resting and exercise) is usually normal but may show atrial or ventricular arrhythmia. • Holter monitor detects arrhythmias. Treatment • Corresponds to degree of mitral regurgitation • In the presence of regurgitation, antibiotic prophylaxis before invasive procedures to prevent infective endocarditis (considered moderate risk for SBE) • Beta-adrenergic blockers • Measures to prevent hypovolemia, such as avoidance of diuretics, because hypervolemia can decrease ventricular volume, thereby increasing stress on the prolapsed mitral valve • Surgical repair or valve replacement with severe mitral regurgitation

Complications • Mitral regurgitation • Infective endocarditis • Arrhythmias

Signs and Symptoms • Commonly produces no symptoms • Late systolic regurgitant murmur • Midsystolic click • Palpitations, arrhythmias, and tachycardia • Light-headedness or syncope • Fatigue, especially in the morning; lethargy; weakness • Dyspnea and hyperventilation

• Chest tightness and atypical chest pain • Anxiety, panic attacks, and depression

70  Part II • Disorders