Chapter 201 Cardiovascular Disease in Pregnancy
THE CHALLENGE
Cardiac disease is one of the major causes of nonobstetric maternal mortality. Whereas in the past patients with congenital heart disease did not survive to reproductive age, it is now common for these patients to become pregnant, be it planned or unplanned.
Scope of the Problem: Cardiac disease complicates approximately 1% of all pregnancies. Mitral valve prolapse may be found in 5% to 7% of pregnant women. The type and severity of risk vary with the type of lesion and the functional abilities of the patient (see box). Patients with valvular disease have an increased risk for thromboembolic disease, subacute bacterial endocarditis, cardiac failure, and pulmonary edema during and after pregnancy.
Objectives of Management: Identify patients at risk because of cardiovascular conditions, provide realistic counseling regarding the risk to mother and fetus, and work to reduce this risk. The basis of antepartum management consists of frequent evaluations of maternal cardiac status and fetal well-being, combined with avoidance of conditions or actions that increase cardiac workload. The latter includes the treatment or avoidance of anemia, prompt treatment of any infection or fever, limitation of strenuous activity, and adherence to appropriate weight gain.
TACTICS
Relevant Pathophysiology: By midpregnancy there is a 40% increase in cardiac output; this increase in demand may be fatal. Cardiac output shows an additional increase in the immediate postpartum period, as up to 500 mL of additional blood enter the maternal circulation because of uterine contractions and rapid loss of uterine volume. Cardiac complications, such as peripartum cardiomyopathy, may occur up to 6 months after delivery. Valvular heart disease is the most commonly encountered cardiac complication of pregnancy, with rheumatic valvular disease being the most frequent type. The severity of the associated valvular lesion determines the degree of risk associated with pregnancy. Roughly 90% of these patients have mitral stenosis, which may result in worsening obstruction as cardiac output increases during the pregnancy. When severe or associated with atrial fibrillation, the risk of cardiac failure during pregnancy is increased.
Strategies: The New York Heart Association classification of heart disease is a useful guide to the risk of pregnancy (see box). Patients with class I or II disease, such as those with septal defects, patent ductus arteriosus, or mild mitral or aortic valvular disease, generally do well during pregnancy, although their fetuses are at greater risk for prematurity and low birthweight. Patients with class III or IV disease caused by primary pulmonary hypertension, uncorrected tetralogy of Fallot, Eisenmenger syndrome, or other conditions rarely do well, with pregnancy inducing a significant risk of death, often in excess of 50%. Patients with this degree of cardiac decompensation should be advised to avoid pregnancy or consider termination based on careful consultation with specialists in both cardiology and high-risk obstetrics.
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