Cardiac Disease during pregnancy

CARDIAC DISEASE

With earlier diagnoses and more effective treatments, more women with congenital and acquired heart disease reach adulthood and may become pregnant. Patients with rheumatic heart disease (caused by untreated or delayed treatment of group A–hemolytic streptococcal [GAS] ton-sillopharyngitis) and acquired infectious valvular heart dis-ease (often associated with drug use) comprise only 50% of pregnant cardiac patients. The remainder consists of other cardiac conditions that traditionally have been less commonly seen in pregnancy. Because pregnancy is itselfassociated with an increase in cardiac output of 40%, the risks to mother and fetus are often profound for women with pre-existing cardiac disease. Ideally, cardiac patients should havepreconceptional care directed at maximizing cardiac func-tion. They should also be counseled about the risks their particular heart disease poses in pregnancy.

Classification of Heart Diseases in Pregnancy

The classification of heart disease by the New York Heart Association is useful to evaluate all types of cardiac patients with respect to pregnancy (Table 14.2). It is a functional classification and is independent of the type of heart dis-ease. Patients with septal defects, patent ductus arteriosus, and mild mitral and aortic valvular disorders often are in classes I or II and tend to do well throughout pregnancy. Primary pulmonary hypertension, uncorrected tetralogy of Fallot, Eisenmenger syndrome, Marfan syndrome with significant aortic root dilation, and certain other conditions are associated with a much worse prognosis (frequently death) through the course of pregnancy. For this reason, patients with such disorders are strongly advised not to become pregnant.

Management

General management of the pregnant cardiac patient con-sists of avoiding conditions that add additional stress to the workload of the heart beyond that already imposed by preg-nancy, including prevention and/or correction of anemia, prompt recognition and treatment of any infections, a de-crease in physical activity and strenuous work, and proper weight gain. Adequate rest is essential. For patients with class I or II heart disease, increased rest at home is advised; and in cases of higher class levels, hospitalization and treatment of cardiac failure may be required. Coordinated management between obstetrician, cardiologist, and anes-thesiologist is especially important for patients with sig-nificant cardiac dysfunction.

The fetuses of patients with functionally significant cardiac disease are at increased risk for low birth weight and prematurity. A patient with congenital heart disease is1% to 5% more likely to have a fetus with congenital heart disease than is someone without this condition; antepartum fetal cardiac assessment using ultrasound is recommended.

The antepartum management of pregnant cardiac pa-tients includes serial evaluation of maternal cardiac status as well as fetal well-being and growth. Anticoagulation, antibiotic prophylaxis for subacute bacterial endocarditis, invasive cardiac monitoring, and even surgical correction of certain cardiac lesions during pregnancy can all be ac-complished if necessary. The intrapartum and postpartum management of pregnant cardiac patients includes consid-eration of the increased stress of delivery and postpartum physiologic adjustment. Labor in the lateral position to fa-cilitate cardiac function is often desirable. Every attempt is made to facilitate vaginal delivery because of the in-creased cardiac stress of cesarean section. Because cardiac output increases by 40% to 50% during the second stage of labor, shortening this stage by the use of forceps or vac-uum extractor is often advisable. Epidural anesthesia to re-duce the stress of labor is also recommended. Even with patients who are stable at the time of delivery, cardiac out-put increases in the postpartum period because of the ad-ditional 500 mL added to the maternal blood volume as the uterus contracts. Indeed, most obstetric patients who die with cardiac disease do so following delivery.

Rheumatic heart disease remains a common cardiacdisease in pregnancy. As the severity of the associated valvu-lar lesion increases, the risk for thromboembolic disease, subacute bacterial endocarditis, cardiac failure, and pulmonary edema increases. A high rate of fetal loss also occurs in women with rheumatic heart disease. Approximately 90% of these pa-tients have mitral stenosis, whose associated mechanical obstruction worsens as cardiac output increases during pregnancy. Women with mitral stenosis associated with atrial fibrillation have an especially high risk of develop-ing congestive heart failure.

Maternal cardiac arrhythmias are occasionally en-countered during pregnancy. Paroxysmal atrial tachycardia is the most commonly encountered maternal arrhythmia and is usually associated with overly strenuous exercise. Underlyingcardiac disease such as mitral stenosis should be suspected when atrial fibrillation and flutter are encountered.

Peripartum cardiomyopathy is an unusual but espe-cially severe cardiac condition identified in the last month of pregnancy or the first 6 months following delivery. It is difficult to distinguish from other cardiomyopathies (e.g., myocarditis) except for its association with pregnancy. In many cases, no apparent cause can be determined. Treatment is generally unchanged from cardiac failure un-associated with pregnancy, except that the use of angiotensin-converting enzyme inhibitors is avoided if the patient is pregnant. Management includes bed rest, digoxin, diuretics, and, in some cases, anticoagulation. The mortality rate is high and is related to cardiac size 6 to 12 months later. If cardiac size returns to normal, prognosis is improved, although it remains guarded. Sterilization counseling is warranted for patients with cardiomyopathy.