Cardiac disease complicates only 1% to 4% of pregnancies in the United States, yet it is still the most important cause of nonobstetric maternal morbidity and mortality.1 Structural heart disease refers to an interruption of the natural flow of blood through the chambers and valves of the heart. The pathology may be congenital or acquired, typically involving myocardial and valvular lesions. Structural heart disease also includes noncoronary cardiovascular processes and the related interventional procedures to repair the defects.2 Ischemic disease (atherosclerosis of native coronary arteries) and cardiomyopathies presenting with pulmonary edema are discussed separately (see Chapters 6 and 8).
Preconception counseling and planned pregnancy after risk stratification of every woman with structural heart disease in the child-bearing period is important to reduce the maternal and fetal morbidity and mortality.3 Successful pregnancies can be achieved when cardiac complications are managed during pregnancy, using a multidisciplinary team approach for diagnosis and treatment. The team should have a cardiologist, obstetrician, and anesthesiologist with experience in cardiac disease in pregnancy. Higher risk cases may require the immediate availability of a neonatal specialist and a cardiothoracic surgeon. Antenatal care should focus on optimization of cardiovascular function with appropriate dosing of medications, some of which may need to be altered to avoid teratogenicity. The plan for management of labor, delivery, and the postpartum should be in place before the third trimester.
If there is a strong suspicion of structural heart disease during pregnancy, confirmatory tests should be initiated. Echocardiography should be performed in any pregnant patient with unexplained or new cardiovascular signs or symptoms.4 When ventricular function cannot be accurately assessed by echocardiography, magnetic resonance imaging (MRI) should be performed. MRI may be used to evaluate complex heart disease or aortic pathology. Chest radiography and computed tomography (CT), with ionizing radiation risks, are usually not necessary to diagnose structural heart disease. One exception for the use of CT during pregnancy is to diagnose or exclude pulmonary embolism.4
RISK OF HEART DISEASE IN PREGNANCY
Several studies have shown that women with heart disease have an increased risk of maternal and neonatal complications. A registry with patients from 28 countries concluded that most women with structural heart disease have safe pregnancies as long as pre-pregnancy counseling and specialized care are available. Maternal functional status before pregnancy is one of the most important predictors of both maternal and neonatal outcomes. Pregnancy outcome is better in New York Heart Association (NYHA) class I/II women compared with class III/IV and in those with successful cardiac interventions before pregnancy5 (see Table 5-1). Despite high-quality care, these patients must recognize that complication rates are higher and maternal mortality may approach 1% (compared with 0.007% in the normal population).6
TABLE 5-1Classification of Heart Failure