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Part II
• Disorders
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.
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
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
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.