Special Feature
Mitral Valve Prolapse in Pregnancy
By Steven G. Gabbe, MD
Mitral valve prolapse (mvp) is the most common abnormality of the cardiac valves and the most common cause of severe mitral regurgitation in the United States.1 However, there is considerable controversy about its prevalence, diagnosis, and management in pregnancy. This review describes the anatomic and physiologic changes associated with MVP in pregnancy, including echocardiographic characteristics and the differences in risk associated with anatomic vs. functional. A plan for the care of the pregnant woman with MVP will be suggested.
MVP has been defined as billowing of the mitral leaflets into the left atrium during systole.2 The mitral leaflets do not close completely and regurgitation develops. Two phenotypic patterns have been described—an anatomic form with thickened leaflets, which may lead to progressive valvular pathology that is seen in 15-20% of patients, and a functional form characterized by a dynamic expansion or enlargement of the mitral annulus during systole. On auscultation, MVP is characterized by a nonejection systolic click that corresponds to filling of the relaxed mitral valve leaflets.1 A late systolic murmur of mitral regurgitation may be heard. With progression to severe mitral regurgitation, the click may disappear and an S3 gallop and rales and dyspnea may be observed.
The diagnosis of MVP must be made with two-dimensional echocardiography. Classic MVP, which corresponds to the anatomic form, is characterized by displacement of the mitral valve leaflets into the left atrium by more than 2 mm and a maximum thickness of the leaflets of at least 5 mm. In contrast, the nonclassic form of MVP, which corresponds to the functional form, reveals displacement of the leaflets by at least 2 mm into the left atrium but without leaflet thickening.2 Functional MVP is observed in 80% of patients and usually resolves with age. It is characterized by reduction in left ventricular size with a relatively larger mitral valve annulus and mitral leaflets. In contrast, the anatomic or classic form is most often seen in men after the age of 45 and is often associated with connective tissue disorders such as Marfan syndrome. It is this form of MVP that leads to elongation and rupture of the valvular chordae tendinae and is associated with atrial fibrillation, infective endocarditis, and embolic complications. A variety of symptoms have been associated with the functional form of MVP, including chest pain, palpitations, arrhythmias, fatigue, dyspnea, and syncope. However, recent studies have shown that these symptoms are not specific for or increase in individuals with MVP. In fact, echocardiography has not been recommended in individuals with these noncardiac symptoms.3
The prevalence of MVP was reported to be as high as 17% among young women. However, more recent studies, using carefully defined echocardiographic characteristics, have documented this valvular abnormality in approximately 3% of women.2 Should a patient report a history of MVP, it is important to confirm the diagnosis by two-dimensional echocardiography if that study has not been performed in the past.
During pregnancy, the auscultatory findings of MVP are usually less prominent. The increased intravascular volume of pregnancy and decreased systemic vascular resistance lead to an increase in the dimensions of the left ventricle and mitral valve annulus with a reduction in prolapse.1 Patients with MVP can be reassured that pregnancy will not increase the risk for antepartum or intrapartum complications. Establishing the diagnosis of MVP will again require a careful clinical examination and echocardiography. During labor, epidural anesthesia can be used safely. Antibiotic prophylaxis during labor remains controversial.4 The American Heart Association does not recommend endocarditis prophylaxis for vaginal delivery or for cesarean section in patients with MVP, either with or without mitral regurgitation. On the other hand, some cardiologists and obstetricians believe the benefit of antibiotic prophylaxis outweighs the potential risks. I prefer to use antibiotics for patients with a diagnosis of MVP established by echocardiography, administering ampicillin (2 g IV or IM) and gentamicin (1.5 mg/kg IV or IM) in the active phase of labor followed by a second dose 8 hours after the initial dose. For those allergic to ampicillin, vancomycin is used (1 g IV over 1 hour with gentamicin, 1.5 mg/kg IV or IM) in the active phase of labor, with the second dose eight hours later.
In summary, MVP is a common valvular abnormality in women, although the prevalence is lower than originally thought. Most patients will have the functional form of MVP, which is not associated with serious complications and will improve with age. Pregnancy in the patient with MVP is not associated with an increase in antepartum or intrapartum complications. The use of antibiotic prophylaxis to prevent infective endocarditis in these patients remains controversial.
References
1. Hanson EW, et al. Mitral valve prolapse. Anesthesiology 1996;85:178-195.
2. Freed LA, et al. Prevalence and clinical outcome of mitral-valve prolapse. N Engl J Med 1999;341:1-7.
3. Nishimura RA, McGoon MD. Perspectives on mitral-valve prolapse. N Engl J Med 1999;341:48-50.
4. Teerlink JR, Foster E. Valvular heart disease in pregnancy. A contemporary perspective. Cardiol Clin 1998; 16:573-598.
The prevalence of mitral valve prolapse in women is:
a. 1%.
b. 3%.
c. 10%.
d. 15%.
e. 20%.
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