|
Heart disorders account for about 10% of maternal obstetric deaths. In the US, because incidence of rheumatic heart disease has markedly declined, most heart problems during pregnancy result from congenital heart disease. Pregnancy is inadvisable for women with certain high-risk disorders (eg, pulmonary hypertension, severe valvular disorders, prior postpartum cardiomyopathy).
Pathophysiology
Pregnancy stresses the cardiovascular system, often worsening known heart disorders or unmasking occult heart disorders. Stresses include decreased Hb and increased blood volume, stroke volume, and eventually heart rate. Cardiac output increases by 30 to 50%. These changes become maximal between 28 and 34 wk gestation. During labor, cardiac output increases about 20% with each uterine contraction; other stresses include straining during the 2nd stage of labor and the increase in venous blood returning to the heart from the contracting uterus. Cardiovascular stresses do not return to prepregnancy levels until several weeks after delivery.
Symptoms and Signs
Findings resembling heart failure (eg, mild dyspnea, systolic murmurs, jugular venous distention, tachycardia, dependent edema, mild cardiomegaly seen on chest x-ray—see Heart Failure: Introduction) typically occur during pregnancy. However, they may result from a heart disorder or from pregnancy itself. Diastolic or presystolic murmurs are more specific for heart disorders. Mild heart disorders may first become evident during pregnancy.
Heart failure can cause premature labor or arrhythmias. Risk of maternal or fetal death correlates with New York Heart Association functional classification, which is based on the amount of physical activity that causes symptoms of heart failure. Risk is not increased if symptoms do not occur with exertion (class I) or occur only with significant exertion (class II). Risk is increased if symptoms occur with mild exertion (class III) or with minimal or no exertion (class IV).
Diagnosis
and Treatment
Diagnosis is usually clinical and by echocardiography.
Frequent prenatal visits, ample rest, avoidance of excessive weight gain and stress, and treatment of anemia are required. An anesthesiologist familiar with heart disorders in pregnancy should attend the labor. During labor, pain and anxiety are treated aggressively to minimize tachycardia. Women are closely monitored immediately postpartum and are followed for several weeks postpartum by a cardiologist.
Heart
failure:
Before women with class III or IV heart failure conceive, the disorder should be optimally treated medically and, if indicated (eg, if due to a valvular heart disorder), treated surgically.
Pregnant women with heart failure require hospitalization and bed rest. Those with class III heart failure may require digoxin 0.25 mg po once/day plus bed rest beginning at 20 wk. Cardiac glycosides (eg, digoxin , digitoxin ) cross the placenta, but neonates (and children) are relatively resistant to their toxicity. Women with class IV heart failure may be advised to obtain early therapeutic abortion. ACE inhibitors are contraindicated because they may cause fetal renal damage. Other treatments for heart failure (eg, diuretics, nitrates, inotropes) may be continued during pregnancy depending on disease severity and fetal risk, as determined by a cardiologist and a perinatologist.
Arrhythmias:
Atrial fibrillation may accompany cardiomyopathy or valvular lesions. Rate control is usually similar to that in nonpregnant patients, with β-blockers, Ca channel blockers, or digoxin (see Arrhythmias and Conduction Disorders: Drugs for Arrhythmias). Certain antiarrhythmics (eg, amiodarone ) should be avoided. In patients with new-onset atrial fibrillation or hemodynamic instability, cardioversion may be used to restore sinus rhythm. Anticoagulation may be required because the relative hypercoagulability during pregnancy makes atrial thrombi (and subsequent systemic or pulmonary embolization) more likely. Although neither standard heparin nor low mol wt heparins cross the placenta, low mol wt heparins have less risk of thrombocytopenia. Warfarin crosses the placenta and may cause fetal abnormalities (see Table 2: Pregnancy Complicated by Disease: Drugs With Adverse Effects During Pregnancy  ), particularly during the 1st trimester. Warfarin use during the last month of pregnancy also has risks. Rapid reversal of warfarin 's anticoagulant effects may be difficult and may be required due to fetal/neonatal intracranial hemorrhage resulting from birth trauma or due to maternal bleeding (eg, resulting from trauma or emergency cesarean delivery).
Management of acute supraventricular or ventricular tachycardia is the same as for nonpregnant patients.
Endocarditis
prophylaxis:
For pregnant patients with a structural heart disorder, indications and use of endocarditis prophylaxis for nonobstetric events are the same as for nonpregnant patients (see Endocarditis: Prevention); those with rheumatic heart disease are given daily prophylaxis. Although rate of bacteremia with uncomplicated vaginal or caesarean delivery is low and routine prophylaxis is not recommended by the American College of Cardiology, many obstetricians give prophylactic antibiotics shortly before and after delivery for patients with valvular disease.
Valvular
Stenosis
and Insufficiency
Stenosis and regurgitation (insufficiency) in pregnancy most often affect the mitral and aortic valves. Pregnancy amplifies the murmurs of mitral and aortic stenosis but diminishes those of mitral and aortic regurgitation. During pregnancy, mild mitral or aortic regurgitation is usually easy to tolerate; stenosis is more difficult to tolerate and predisposes to maternal and fetal complications. Mitral stenosis is especially dangerous; the tachycardia, increased blood volume, and increased cardiac output during pregnancy interact with this disorder to increase pulmonary capillary pressure, causing pulmonary edema. Atrial fibrillation is also common.
Treatment
Ideally, valvular disorders are diagnosed and treated medically before conception; surgical correction is often recommended for severe disorders. Prophylactic antibiotics are required in certain situations (see Pregnancy Complicated by Disease: Endocarditis prophylaxis).
Mitral stenosis:
Patients must be closely observed throughout pregnancy because mitral stenosis may rapidly become more severe. If required, valvotomy is relatively safe during pregnancy; however, open heart surgery increases fetal risk. During labor, conduction anesthesia (eg, epidural or spinal nerve block by a local anesthetic) is usually preferred.
Aortic stenosis:
During labor, local anesthesia or, if necessary, general anesthesia, is preferred. Conduction anesthesia decreases filling pressures (preload), which may already be decreased by aortic stenosis. Straining, which can suddenly reduce filling pressures and impair cardiac output, is discouraged during the 2nd stage of labor; operative vaginal delivery may be preferred, if feasible. Cesarean section is done if indicated (see Abnormalities and Complications of Labor and Delivery: Cesarean Section).
Other Heart
Disorders
in Pregnancy
Mitral
valve prolapse:
This disorder occurs more frequently in younger women and tends to be familial. Mitral valve prolapse is usually an isolated abnormality but may cause some degree of mitral regurgitation or be accompanied by Marfan syndrome or an atrial septal defect. Women with mitral valve prolapse generally tolerate pregnancy well. The relative increase in ventricular size during normal pregnancy reduces the discrepancy between the disproportionately large mitral valve and the ventricle. Patients with mitral regurgitation may require prophylactic antibiotics during delivery. β-Blockers are indicated for recurrent arrhythmias. Rarely, thrombi and systemic emboli develop and require anticoagulation.
Congenital
heart disease:
For most asymptomatic patients, risk is not increased during pregnancy. However, patients with Eisenmenger's syndrome (now rare), primary pulmonary hypertension, or perhaps isolated pulmonary stenosis are predisposed, for unknown reasons, to sudden death during labor, during the postpartum period (the 6 wk after delivery), or after abortion at > 20 wk gestation. Thus, pregnancy is inadvisable. If patients become pregnant, they should be closely monitored with a pulmonary artery catheter and an arterial line during delivery. For patients with intracardiac shunts, the goal is to prevent right-to-left shunting by maintaining peripheral vascular resistance, and by minimizing pulmonary vascular resistance.
Patients with Marfan syndrome are at increased risk of aortic dissection and rupture of aortic aneurysms during pregnancy. Bed rest, avoidance of Valsalva maneuvers, and measurement of aortic diameter with echocardiography are required.
Peripartum
cardiomyopathy:
Heart failure with no identifiable cause (eg, MI, valvular disorder) can develop between the last month of pregnancy and 5 mo postpartum in patients without a previous heart disorder. Risk factors include multiparity, age ≥ 30, multifetal pregnancy, and preeclampsia. The 5-yr mortality rate is 50%. Recurrence is likely in subsequent pregnancies, particularly in patients with residual cardiac dysfunction; future pregnancies are therefore not recommended. Treatment is as for heart failure (see Pregnancy Complicated by Disease: Endocarditis prophylaxis).
Last full review/revision November 2005
Content last modified November 2005
| 
