Normal pregnancy physiology is characterized by cardiovascular adaptations in the mother. Cardiac output increases markedly as a result of both augmented stroke volume and an increase in the resting heart rate, and the maternal blood volume expands by up to 50%. These changes may not be tolerated well in women with functional or structural abnormalities of the heart. Thus, although only a small number of pregnancies are complicated by cardiac disease, these contribute disproportionately to overall rates of maternal morbidity and mortality. Most cardiac disease in women of childbearing age in the United States is caused by congenital heart disease. Ischemic heart disease, however, is being seen more commonly in pregnant women due to increasing rates of comorbid conditions, such as diabetes mellitus, hypertension, and obesity.
For practical purposes, the best single measurement of cardiopulmonary status is defined by the New York Heart Association Functional Classification (see box). Most pregnant women with cardiac disease have class I or II functional disability, and although good outcomes are generally anticipated in this group, complications such as preeclampsia, preterm birth, and low birth weight appear to occur with increased frequency. Women with more severe disability (class III or IV) are rare in contemporary obstetrics; however, the maternal mortality is markedly increased in this setting and is usually the result of heart failure. Because of these risks, therapeutic abortion for maternal health should be considered in women who are severely disabled from cardiac disease. Specific conditions that have been associated with a particularly high risk for maternal death include Eisenmenger syndrome, primary pulmonary hypertension, Marfan syndrome with aortic root dilatation, and severe aortic or mitral stenosis. In general, these conditions should be considered contraindications to pregnancy.
NEW YORK HEART ASSOCIATION FUNCTIONAL CLASSIFICATION
|Class I ||Uncompromised: No limitation on physical activity. |
|Class II ||Slightly limited: Symptoms present with ordinary physical activity but asymptomatic at rest. |
|Class III ||Markedly limited: Symptoms present with less than ordinary activity but asymptomatic at rest. |
|Class IV ||Severely compromised: Inability to perform any activity without developing symptoms, which may also develop at rest |
The importance of preconceptional counseling for women with heart disease cannot be overstated. A thorough evaluation prior to pregnancy provides an opportunity for comprehensive risk assessment and detailed planning. Once pregnant, women with cardiac disease are best treated by a team of practitioners with experience in caring for such patients. Heart failure and arrhythmias are the most common cardiovascular complications associated with heart disease in pregnancy, and adverse maternal and fetal outcomes are increased when they occur. Symptoms of volume overload should therefore be evaluated and treated promptly. Labor management depends on the underlying cardiac lesion and the degree of disability. Women with a history of arrhythmia should have continuous cardiac monitoring throughout labor, delivery, and the immediate postpartum period. Cesarean delivery is generally reserved for obstetric indications but may be appropriate for ...