Pregnancy in the Woman With Preexisting Cardiovascular Disease

Hemodynamic changes of pregnancy in women with preexisting cardiovascular disease may complicate the course of pregnancy. Historically, underlying rheumatic heart disease was the cause of cardiac complications in pregnancy. However, currently women after complex congenital heart disease surgery or with acquired myocardial disease earlier in life may be at risk during pregnancy.¹ Many of these women are able to sustain a successful pregnancy with careful management. Congenital heart disease in this age group is becoming more common than rheumatic heart disease in developed countries such as the United States and Great Britain.¹

The expected hemodynamic changes of pregnancy, may complicate the course of the pregnancy, labor, delivery, or postpartum recovery in the women with heart disease. This chapter focuses on pregnancy in women with a history of heart disease, including valvular, congenital, aortic, and myocardial diseases. Women with heart disease may be able to have uncomplicated pregnancies. However, potential risks need to be identified, discussed, and treated to facilitate a successful pregnancy. Therapeutic intervention may be necessary to improve the patient's clinical status for a planned pregnancy; therefore, women should undergo preconception evaluation to identify potential problems.

The literature regarding cardiovascular complications of pregnancy is replete with numerous case reports and expanded case reports. At best there are very small series of patients. These are cited in this discussion when a significant potential risk is highlighted, although it is difficult to quantify the incidence or prevalence of the complication.

During pregnancy

The normal hemodynamic alterations that occur during pregnancy are summarized in Table 1. These changes result from the physiologic 40% increase in blood volume with increased cardiac output. These changes begin in early pregnancy peaking at approximately 20 weeks' gestation. Blood volume expands during pregnancy, and plasma volume increases far more than the erythrocyte volume, resulting in relative anemia of pregnancy. The increase in cardiac output, especially in the latter half of pregnancy, is maintained by a 10–20% augmentation in the heart rate. Deconditioning with decreased activity and vigorous exercise may cause further heart rate increases, even with nonstrenuous daily activities.

Table 1. Summary of hemodynamic changes of pregnancy

Stroke volume increases, also, thereby contributing to the increased cardiac output early in pregnancy. Stroke volume increases preload on the heart. Augmented preload may not be tolerated by obstructive cardiac lesions, such as mitral or aortic stenosis, or with impaired ventricular function. Normal pulmonary compliance can accommodate this additional blood volume and preload burden. However, in the setting of pulmonary hypertension when there is reduced pulmonary vascular compliance, right-side heart failure may ensue and left-to-right shunting within the heart reverses, causing decreased oxygen saturation of the blood and cyanosis.

Systemic blood pressure decreases because systemic vascular resistance decreases beginning in early pregnancy. Peripheral vasodilation caused by circulating estrogen and direct arteriovenous connections within the placenta contribute to the decrease in systemic vascular resistance. This effect is maximal in the second trimester. There is a decrease in the mean aortic pressure and a widening of the pulse pressure. This decrease in afterload from systemic vasodilation in a woman with aortic stenosis may further increase the gradient across the aortic valve, adding to the left ventricular work. Conversely, certain cardiac lesions may benefit from afterload reduction, such as mitral regurgitation and aortic insufficiency. These murmurs may soften and the echocardiographic severity of regurgitation decreases during pregnancy.

In the supine position, the gravid uterus compresses the inferior vena cava, acutely decreasing preload and causing the syndrome of supine syncope. Many of the hemodynamic changes of heart rate and stroke volume are attenuated when the patient lies in the left lateral decubitus position. Often, this position is recommended for labor when hemodynamic fluctuations occur over a short period of time and may be deleterious for patients with certain types of cardiac lesions.

Labor and delivery

The hemodynamic changes of labor and delivery pose potential problems for the woman with heart disease, and should be anticipated. With each uterine contraction during labor, there is a bolus of fluid into the intravascular space.² This change, although transient, is repetitive and may exacerbate certain cardiac problems by augmenting cardiac output by 15–20%, with a 10% increase in mean systemic arterial blood pressure.² A reflex bradycardia may occur. These changes have been shown to be attenuated with the patient lying in the left lateral decubitus position.³ Pain and anxiety stimulate the sympathetic nervous system, causing an increase in blood pressure and heart rate. The prolonged Valsalva maneuver required during the second stage of labor may increase blood pressure and afterload, potentially complicating aortic disease. Epidural anesthesia is instituted slowly with proper rehydration to provide pain control and to prevent marked fluctuations in blood pressure. The vasodilatation from the epidural may result in a precipitous decrease in blood pressure, and the woman with obstructive valvular disease or a cardiomyopathy may experience pulmonary edema with vigorous fluid resuscitation.

There is some information about the circulatory changes that occur during pregnancy, labor, and delivery; but, relatively little is known about what occurs after the time of delivery. Postpartum hemodynamic changes may resolve by 6 weeks, but it may take up to 12 weeks for the cardiovascular changes of pregnancy to resolve.⁴ No hemodynamic differences have been noted between women who breastfeed and those who do not.

Preconception evaluation

Ideally, women with cardiac disease should undergo a thorough preconception evaluation to identify risks of pregnancy and need for immediate treatment to improve her cardiac status. This evaluation helps the health professionals and the patient anticipate potential problems that may arise. Specific diagnostic modalities are outlined to help focus diagnostic testing for specific clinical problems. How hemodynamic consequences of pregnancy may impact assessed specific cardiac lesions needs to be addressed. Valvular regurgitation may improve during pregnancy, whereas stenotic lesions become complicated and pose a greater risk to the patient during pregnancy.

Congenital heart disease complicated by pulmonary hypertension or primary pulmonary hypertension is an absolute contraindication to pregnancy.⁵ Absolute and relative contraindications and the associated specific risks to the patient are summarized in Table 2. Women with primary pulmonary hypertension or secondary pulmonary hypertension of Eisenmenger's syndrome are at considerable risk for maternal mortality. Women with pulmonary hypertension lack sufficient pulmonary compliance to accommodate increased preload; therefore, heart failure or shunt reversal may occur during pregnancy. Pregnancy can increase cyanosis, complicating fetal growth and development.

A woman with an impaired ventricle and reduced functional status may not withstand the hemodynamic changes of pregnancy and be at risk for cardiac decompensation during and after pregnancy. Specifically, at risk are women with New York Heart Association (NYHA) functional class III–IV, which denotes symptoms of heart failure with minimal activity or at rest. Women with Marfan syndrome or other causes of aortic dilatation, for example, are at risk for aortic dissection and rupture during the third trimester. Women with severe mitral or aortic stenosis may not be able to accommodate the increased preload and might experience pulmonary edema and/or severe tachyarrhythmias.⁶ Because of these potentially dangerous situations, women with significant cardiac disease should undergo preconception evaluation to identify and stratify risks. When counseling a woman before conception, her long-term survival and whether pregnancy may alter the natural history of her cardiac disease must be considered and discussed.

Table 2. Cardiovascular contraindications to pregnancy and potential problems

*NYHA III–IV New York Heat Association functional class.

Previous diagnostic evaluation and record of interventions and surgeries are important to review to determine the current cardiovascular status in the woman with preexisting heart disease and the feasibility pregnancy. This analysis helps to anticipate the effect of pregnancy on residual disease. It is important to probe the woman's functional capacity, her exercise history, and her ability to perform daily activities. The woman with normal function status (NYHA I) and normal ventricular function despite the presence of cardiovascular disease is more likely to sustain a normal pregnancy. Current medications must be evaluated for potential maternal or teratogenic risk (Table 3). Medications with known fetal risks, such as angiotensin-converting enzyme (ACE) inhibitors and angiotensin-receptor blockers (ARBS), should be changed to another vasodilator, such as hydralazine, either before conception or as early in pregnancy as possible.

Table 3. Common cardiovascular medications and pregnancy

*unfractioned and low-molecular weight forms.

Full cardiac evaluation includes diagnostic tests appropriate to assess feasibility and safety of pregnancy. This may include stress-testing to quantify functional capacity. Cardiac catheterization may be indicated to assess hemodynamics, valve disease severity, and need for catheter-based interventions. Evaluation may conclude that cardiac surgery is indicated to actually improve the outcome of a future pregnancy. Genetic evaluation counseling may be indicated for the woman with congenital heart disease.

Evaluation during pregnancy

Symptoms that arise during the course of a normal pregnancy are similar to those reported by patients with cardiac disease (Table 4). Certain symptoms may occur during the course of a normal pregnancy, whereas other symptoms may be abnormal and require further investigation. When obtaining a history from a pregnant woman with cardiovascular disease or from a patient who wishes to become pregnant, the clinician must specifically establish whether there are symptoms related to pulmonary hypertension, left ventricular dysfunction, or a hemodynamically significant arrhythmia.

Table 4. Cardiovascular symptoms during pregnancy

Physical findings detected during a normal pregnancy may be similar to those of patients who present with cardiac disease (Table 5). Abnormal cardiovascular signs during pregnancy may be due to pulmonary hypertension, cyanosis, left ventricular dysfunction, or a hemodynamically significant arrhythmia. The physical findings of pregnancy are caused by expected hemodynamic alterations with increase in heart rate, fluid retention, expanded blood volume, and decreased afterload. Inappropriate sinus tachycardia may be present at rest, especially during the third trimester. The cardiac examination in pregnancy may be notable for a hyperdynamic, diffuse precordial impulse that becomes displaced to the left as pregnancy progresses. The right ventricular impulse may be more prominent. The first and second heart sound may increase. Heart murmurs are heard in nearly 96% of pregnant women; classically, it is a mid-systolic murmur that is heard best along the left sternal border. This is probably the result of increased transvalvular flow from expanded blood volume. There may be a venous hum or a supraclavicular systolic murmur from the brachiocephalic arteries. Tricuspid regurgitation has been noted during pregnancy. As noted, murmurs of mitral and aortic regurgitation may soften because of the decrease in afterload that occurs during the pregnancy. Because of increased preload and increased flow across the stenotic valve, murmurs of mitral stenosis and aortic stenosis are intensified. Peripheral edema caused by fluid retention and decreased plasma oncotic pressure also is seen during pregnancy and may increase with maternal age. The pedal edema caused by pregnancy improves with rest, the lateral decubitus position, elevation of the feet, and support hose. Neck veins may be prominent during pregnancy because of the generalized vasodilation and increased stroke volume.

Table 5. Cardiovascular examination during pregnancy

Electrocardiographic evaluation

The resting electrocardiogram may change with pregnancy (Table 6). The QRS axis may shift leftward as the heart becomes displaced laterally in the thorax, and nonspecific ST-T wave changes may be noted. There also may be frequent atrial or ventricular premature beats. Women have increased atrial and ventricular ectopy during pregnancy and may experience palpitations. For detection of an arrhythmia not documented on a standard 12-lead electrocardiogram, a 24-hour or 48-hour ambulatory Holter monitor may detect the presence of arrhythmia daily. If the arrhythmia is sporadic but is associated with symptoms, then a 30-day event monitor may be more useful to capture the arrhythmia when it occurs.

Table 6. Cardiac diagnostic testing during pregnancy

An electrocardiographic stress test may be performed during pregnancy to assess functional capacity, identify ischemia, or provoke suspected arrhythmias. Stress testing can be performed safely during pregnancy, usually to the predetermined heart rate endpoint of 120–140 beats/min, depending on the patient's functional state and her exercise history. In a study of maximal stress testing during the third trimester, cardiac work efficiency was preserved but a blunted respiratory response was noted.⁷ Exercise stress testing should not be performed in conjunction with radionuclide isotopes imaging, because these agents concentrate in the bladder and constitute a risk to the developing fetus. Stress testing combined with echocardiography may be useful to detect ischemia occurring with exercise.

Echocardiographic evaluation

Echocardiography can be used during pregnancy without risk to the mother or fetus. There has been concern regarding the use of ionizing radiation for the diagnosis of cardiac disorders in pregnancy; therefore, echocardiography provides an excellent diagnostic modality for most cardiac conditions during pregnancy. Serial two-dimensional echocardiography can help to detect changes in cardiac chamber dimensions, wall thickness, or the presence of a pericardial effusion occurring or changing during pregnancy. Chamber enlargement may occur in a normal pregnancy, with an increase in the fractional shortening. Left ventricular muscle mass as determined by echocardiography may increase during a normal pregnancy and may increase further in the setting of preeclampsia.^{8, 9, 10} Doppler echocardiography can help to diagnose and follow the course of stenotic or regurgitant valvular lesions and estimate right-side cardiac pressures to detect pulmonary hypertension. Mitral and tricuspid valve regurgitation have been noted during pregnancy in the structurally normal heart.¹¹ Physiologic mitral regurgitation has been thought to be secondary to annular dilatation with the expected ventricular enlargement.^{2, 11} The transesophageal echocardiogram is useful for the diagnosis of atrial thrombus, atrial septal defect, and aortic disease, such as thoracic aortic dissection.¹²

Hemodynamic and angiographic evaluation

Cardiac catheterization and angiography may be required to diagnose the severity of coronary artery disease in patients with anginal symptoms. Right-side heart catheterization may be needed to definitively diagnose the severity of pulmonary hypertension, quantify intracardiac shunts, and assess severe valvular disease. This procedure should be performed only when clinically indicated. It should be performed with abdominal shielding.

Magnetic resonance imaging

Magnetic resonance imaging defines the cardiac anatomy and is particularly useful in the diagnosis of congenital heart disease and aortic disease.¹³ It usually is performed after the first trimester. Gadolinium is commonly not used during pregnancy.

Historically, rheumatic heart disease was the major cause of valvular heart disease in women of childbearing age. Although rheumatic heart disease occurs less commonly in developed countries, the sequelae of rheumatic heart disease remain a problem in the third world; therefore, it becomes a significant health issue for patients who have immigrated to North America and present during pregnancy.¹ In recent years, congenital valvular heart disease has been increasingly recognized.¹⁴ This includes valvular disease diagnosed at birth or during childhood, with its sequelae diagnosed during adulthood in the young woman. Valvular heart disease, despite the etiology, is discussed later. Potential complications are summarized in Table 7. The clinical differences between rheumatic or congenital etiology are highlighted. Valvular heart disease in general is associated with not only increased risk for cardiovascular complications but also obstetric complications. There is increased incidence of preterm delivery, intrauterine growth retardation, and lower birth weight in women with valvular heart disease.¹⁴

Table 7. Valvular heart disease in pregnancy

Tricuspid valve

Tricuspid valve involvement in rheumatic heart disease usually is mild and occurs with multivalvar involvement. The tricuspid valve is often involved in complex congenital cardiac disease or after surgical repair. In general, tricuspid regurgitation is well tolerated during pregnancy unless it is secondary to a cardiomyopathy or associated with forms of repaired congenital heart disease (see tetralogy of Fallot).¹⁵ Severe tricuspid valve regurgitation caused by previous endocarditis is rare but has been associated with illicit intravenous drug use.

Rheumatic tricuspid stenosis usually occurs with mitral and/or aortic valve involvement. This occurs more commonly in women and is often well tolerated, even when intervention has been required for mitral or aortic disease.¹⁶

Pulmonic valve

Pulmonic valvar stenosis is most often congenital in origin. In adults, it is well tolerated when of mild or moderate severity.¹⁷ There is an increased risk in pregnancy if the woman is asymptomatic and has normal exercise tolerance.⁵ Severe pulmonic stenosis may require percutaneous balloon valvotomy, which is best performed before pregnancy. The woman with severe pulmonic stenosis may become symptomatic, with the increased preload of pregnancy, and may have secondary tricuspid regurgitation. Pulmonic stenosis is often associated with other congenital heart disease such as tetralogy of Fallot. It may also be present after tetralogy of Fallot repair. Branch pulmonary artery stenosis may cause an increased gradient across the pulmonic valve and, if severe, may require percutaneous stent placement. Pulmonic insufficiency usually is well tolerated during pregnancy as long as right ventricular function is normal and tricuspid regurgitation is minimal.^{5, 17}

Mitral valve

MITRAL STENOSIS

Mitral stenosis is the most common rheumatic valvular lesion diagnosed during pregnancy.¹ Rheumatic carditis can result in mitral stenosis, mitral regurgitation, or both. In uncomplicated mitral stenosis, pulmonary venous hypertension develops as a result of the gradient required to maintain adequate transvalvar blood flow. Increased pulmonary pressure causes right ventricular dilation with dysfunction and tricuspid regurgitation. Patients may present with overt right heart failure. Because of obstruction to outflow from the left atrium, the increased volume load during pregnancy may cause a woman to have symptoms for the first time in her life. The expanded stroke volume, augmented cardiac output, and increased heart rate of pregnancy hemodynamically challenge the woman with mitral stenosis. Expanded blood volume and left atrial enlargement enhance the risk of atrial fibrillation. Atrial dilation and atrial fibrillation in the hypercoaguable pregnant patient can promote thrombus formation in the left atrial appendage, necessitating therapeutic anticoagulation to prevent systemic embolization. The best drug for anticoagulation during pregnancy remains controversial, but atrial fibrillation with mitral stenosis requires full, systemic anticoagulation.⁶ Prophylactic doses (for prevention of deep venous thromboses) are inadequate in this setting. Poor cardiac output or atrial fibrillation with increased ventricular response rate may compromise blood flow to the uterus. Previously, it had been noted that infants had lower birth rates when born to mothers with mitral stenosis. During pregnancy, it is important to continue rheumatic fever prophylaxis with daily penicillin.⁶

After auscultation of a diastolic rumble and opening snap, the diagnosis of mitral stenosis can be confirmed by two-dimensional and Doppler echocardiography. Left atrial size and ventricular function can be assessed. Pulmonary arterial pressure can be estimated by the velocity of the tricuspid regurgitation jet and the transmitral gradient assessed with Doppler echocardiography. Thrombi of the left atrial appendage are best visualized with transesophageal echocardiogram. The transmitral gradient by echocardiography may appear higher because of the increased cardiac output and velocity of blood flow that occurs in the latter half of pregnancy.¹⁸ This higher assessed gradient may translate into a smaller calculated valve area.¹⁸ During pregnancy, echocardiography is helpful to monitor left atrial size, left ventricular function, or worsening of the mitral stenosis.

The major risks during pregnancy are atrial fibrillation, embolic events, and pulmonary edema. This usually occurs in women who have NYHA functional class II or III¹⁹ or in those who have impaired left ventricular function.⁶ The severity of mitral stenosis correlated with adverse fetal outcome in one study of 74 women.¹⁹ Women with mild symptoms may respond to limitation of physical activity and restriction of dietary sodium. Selective beta-adrenergic blockade (metoprolol) may help maintain sinus rhythm and slow the heart rate in atrial fibrillation.²⁰ With the use of beta-adrenergic blockers in pregnancy there is the risk of sinus bradycardia, congestive heart failure, bronchospasm, central nervous system effects, nausea, diarrhea, abdominal discomfort, and hypoglycemia. These drugs pass through the placenta and are secreted in breast milk. Adverse fetal effects usually are described when the mother has been treated for hypertension and include intrauterine growth restriction, maternal and fetal bradycardia, delayed neonatal breathing, neonatal hyperglycemia, and neonatal hyperbilirubinemia.

Atrial fibrillation in a pregnant woman with mitral stenosis may result in pulmonary edema or systemic embolization, causing a cerebrovascular event. If atrial fibrillation leads to hemodynamic compromise, electrical cardioversion may be required after adequate systemic anticoagulation.²¹ Adenosine, a naturally occurring substance with a brief half-life, may be administered acutely to treat paroxysmal supraventricular tachycardia.²² Calcium channel blockers, such as verapamil and diltiazem, can be used orally.

Percutaneous transseptal mitral balloon valvuloplasty has been performed in pregnant women with symptoms refractory to medical therapy.²³ This procedure may forestall the need for surgical valve replacement.^{23, 24, 25, 26, 27} Several series of patients have been reported in recent years. In one series there were no deleterious effects of radiation in the child at 5 years.²⁷ Balloon mitral valvuloplasty may not be performed if significant mitral regurgitation or if a left atrial thrombus is present.

Cardiac surgery is indicated when women's symptoms do not resolve, despite medical therapy, and if balloon valvuloplasty is not an option.²⁸ Cardiopulmonary bypass may impact placental circulation and systemic hypothermia may precipitate uterine contractions.²⁹ Surgery, if necessary, is best performed during the second trimester with high-flow, high-pressure, normothermic perfusion and continuous fetal heart rate monitoring.²⁹

Endocarditis prophylaxis at the time of labor and delivery is considered optional for an uncomplicated vaginal or cesarean delivery.³⁰ Labor and delivery may further challenge maternal hemodynamic status in the setting of mitral stenosis. With each contraction, cardiac output increases. Electrocardiographic monitoring for arrhythmia facilitates rapid intervention for tachyarrhythmias to control heart rate. Hemodynamic monitoring with a pulmonary artery catheter can help avoid excessive fluid administration while maintaining adequate perfusion pressure. The pulmonary artery catheter placed during labor and delivery should remain into the early postpartum period because rapid volume shifts also may have adverse hemodynamic effects. The safety of breastfeeding while using medications required during the postpartum period should be carefully evaluated by the pediatrician. For example, heparin is not secreted in breast mild, and warfarin apparently is inactive.

MITRAL REGURGITATION

Mitral regurgitation may be the result of mitral valve prolapse, previous endocarditis, ruptured chordae tendineae, rheumatic disease, or after congenital cardiac repair. Mitral regurgitation and mitral valve prolapse occur as part of the Marfan syndrome. In the presence of normal left ventricular function, pregnancy is well tolerated. Because of the decrease in systemic vascular resistance, the severity of mitral regurgitation may decrease during pregnancy. The ventricular enlargement often decreases mitral valve prolapse and the characteristic “click” may not be auscultated as pregnancy progresses.

The woman with severe mitral regurgitation and limited exercise capacity may benefit from mitral valve repair before conception. Severe symptomatic mitral regurgitation in a woman with NYHA functional class III–IV who does respond to afterload reduction with hydralazine and diuresis may require surgical intervention.⁶

Aortic valve

AORTIC STENOSIS

Severe aortic stenosis is not common in women of childbearing age. It can be a result of rheumatic disease, or previous endocarditis. More often it has been due to a congenitally bicuspid aortic valve that may not have been detected before adulthood. The bicuspid aortic valve may be clinically silent or, if stenotic, symptoms may first develop during pregnancy. This is often associated with coarctation of the aorta, which is discussed later. As seen in mitral stenosis, the severely stenotic lesion may not tolerate the increased cardiac output, stroke volume, and heart rate of pregnancy, resulting in congestive heart failure. A study of 49 pregnancies in 29 women born with aortic stenosis focused upon the outcome of pregnancy.³¹  Severe stenosis defined as valve area <1 cm² or peak gradient >64 mmHg was present in 29 pregnancies (59%). The aortic stenosis was associated with a prior coarctation repair in 29%. Only 6% had cardiac complications: pulmonary edema and atrial arrhythmias occurred in women with sever stenosis. The cesarean section rate was 33%. Mild to moderate aortic stenosis may be well tolerated.^{31, 32} Clinical symptoms often appear after 20 weeks' gestation, when cardiac output is maximal in severe aortic stenosis and is defined as a transvalvular gradient of greater than 64 mmHg.³¹ Chest pain, syncope, or heart failure may occur. Echocardiography delineates the anatomy of the valve, the thickness of the left ventricular walls, and left ventricular function. Doppler echocardiography is used to measure the gradient and to detect regurgitation. The gradient across the aortic valve increases because the velocity of blood flow increases during pregnancy; therefore, the valve may appear more stenotic despite preserved valve area.³³ Congenital aortic stenosis is associated with an increased risk for congenital disease in the offspring.³⁴

Women with critical aortic stenosis, a valve area of less than 1.0 cm², should be discouraged from becoming pregnant, especially if forward cardiac output is compromised, causing symptoms and/or reduced functional capacity. Critical aortic stenosis that is identified before conception may benefit from surgical repair. The Ross procedure has been performed in recent years in young patients with aortic valve pathology. The pulmonic valve is placed in the aortic position and a homograft replaces the pulmonic valve. This obviates the need for long-term anticoagulation. Postoperative complications include pulmonic graft stenosis and neo-aortic insufficiency. There are reports of successful pregnancy after the Ross procedure.³⁴ The choice of valve replacement should be considered carefully in a woman of childbearing age, although this remains controversial.³⁵

A woman of childbearing age who requires porcine valve replacement may face a reoperation, in the future.³⁵ The benefit of a porcine valve or homograft is that therapeutic anticoagulation is not required.³⁵ Currently women of childbearing age with critical aortic disease (stenosis and/or insufficiency) may have had a Ross procedure. A pulmonary autograft replaces the aortic valve and a homograft is placed in the aortic position. The coronary arteries are re-implanted. This surgery obviates the need for a mechanical prosthesis.  Successful pregnancy after pulmonary autograft valve replacement has been described.³⁶ A mechanical valve requires full therapeutic anticoagulation, which further complicates pregnancy by posing risks to mother and fetus. Percutaneous balloon aortic valvuloplasty has been reported during pregnancy when symptoms develop in the second or third trimester.³⁷ This may be a palliative measure to alleviate symptoms during pregnancy. Radiation exposure should be kept to a minimum and the abdomen should be shielded with lead. Surgical intervention may be required if medical management fails and the patient is not a candidate for percutaneous valvuloplasty.^{29, 38} Therefore, if moderate aortic stenosis is identified before pregnancy, it may be best to advise the patient to proceed with pregnancy before stenosis progresses and surgery is required.

Pregnant women with aortic stenosis are particularly dependent on adequate but not excessive preload; however, in the setting of tachycardia, they can experience congestive heart failure. During labor and delivery, a hemodynamic monitoring catheter may facilitate management by maintaining adequate cardiac filling pressures while avoiding excessive preload, which may result in pulmonary edema. Anesthetic agents that would result in significant vasodilation should be used with care, because this would increase the gradient across the aortic valve. Prophylactic antibiotics for endocarditis are no longer medicated in this patient population for a normal vaginal delivery.³⁰

AORTIC INSUFFICIENCY

Aortic insufficiency may be the result of rheumatic fever, endocarditis, vasculitis, aortic dilation, Marfan syndrome, or commonly a congenitally bicuspid aortic valve. Severe aortic insufficiency results in left ventricular dilation, which ultimately causes decreased left ventricular function. The woman with marked left ventricular dilation and left ventricular dysfunction secondary to aortic insufficiency would not tolerate the further volume load of pregnancy. Conversely, mild to moderate aortic insufficiency with normal ventricular size and function is often well tolerated because of the expected vasodilatation and decrease in systemic vascular resistance. Therefore, the murmur of aortic insufficiency may decrease as pregnancy progresses along with the severity of regurgitation by echocardiography.

Women who are treated with ACE inhibitors or angiotensin receptor blockers should be changed to hydralazine for vasodilatation instead in anticipation of pregnancy if possible. Adverse fetal affects of ACE inhibitors have been reported during all trimesters. The medication should be stopped or changed as soon as pregnancy is verified. Antibiotic prophylaxis at the time of labor and a vaginal delivery is no longer indicated.³⁰ Aortic regurgitation caused by active endocarditis during pregnancy may require surgery if the infection cannot be controlled or if hemodynamic deterioration ensues despite medical therapy.⁶

PROSTHETIC VALVES

Thromboembolic events, bleeding, and endocarditis are the major pregnancy risks for women with mechanical prosthetic valves.^{39, 40, 41} Other risks include heart failure, atrial fibrillation, and prosthetic valve thrombosis/dysfunction.⁴¹ The estimated risk of valve thrombosis despite anticoagulation varies between 4% and 14%, and thrombolytic therapy with streptokinase during pregnancy has been described.⁴²

Multiple cutaneous heparin injections may not provide adequate anticoagulation for a mechanical prosthetic heart valve.^{40, 41, 43, 44} There are varying experiences and opinions regarding adequate anticoagulation.^{34, 40, 43, 45, 46, 47} Heparin is a large molecule that does not cross the placenta. The maternal risks of heparin include osteoporosis and bleeding. Subcutaneous administration should be changed to intravenous administration near the time of delivery to allow more precise control, especially when cesarean section is required.⁴⁷ Low molecular weight heparin may be more appropriate and requires less monitoring throughout pregnancy to maintain adequate, therapeutic anticoagulation; however, this drug has been studied only in women at risk for thromboembolic events.^{48, 49} There has been recent controversy surrounding the use of low molecular weight heparin for prosthetic valve anticoagulation during pregnancy. Cases of maternal death despite anticoagulation have been reported and clinicians have been cautioned against its use for this indication.^{50, 51}

Warfarin sodium crosses the placenta and may produce serious adverse and teratogenic effects. This drug, however, offers more reliable therapeutic anticoagulation and has been used in the second and third trimesters.⁵² The warfarin embryopathy includes nasal hypoplasia, saddle nose, and stippled epiphysis.⁴⁵ It has been associated with a high rate of spontaneous abortions and stillbirth risks.⁴⁵ Administered in the second and third trimesters, it has been associated with serious central nervous system defects, including optic atrophy, Dandy-Walker malformation, and agenesis of the corpus colostrum. Hemorrhagic complications may occur during the neonatal period. Warfarin provides effective anticoagulation but causes an embryopathy. A Canadian study indicates that the risk is 6.4%.⁴⁰ The risk was noted to be increased when the dose was more than 5 mg of coumadin.⁵³ Warfarin is associated with a risk of miscarriage that is higher than that associated with heparin.⁵⁴ Despite warfarin use in pregnant women with mechanical valves, thromboembolic events still occurred.⁴⁹ The use of bioprostheses (porcine) may eliminate the need for anticoagulation in the aortic position but not in the mitral position.^{35, 45} Structural valve deterioration has been described in the teenage years and young adulthood, but pregnancy may not contribute to this phenomenon.⁵⁵ The changes in the bioprostheses appear to be independent of pregnancy.^{56, 57} These risks must be considered in any woman of childbearing age who requires valve replacement.^{34, 35}

Due to the advances in the medical and surgical treatment of congenital heart disease more women are reaching childbearing age. In the United States and Europe congenital heart disease complications are more commonly seen than those due to rheumatic disease. McFaul and colleagues¹ reported that congenital heart disease in women with heart disease complicated pregnancy increased from 20% to 40% during the period from 1970 to 1983. The risks and outcome of pregnancy in women with congenital heart disease will vary with the type of congenital heart disease, whether there has been surgical repair, the type of repair, and the sequelae of intervention.^{5, 14, 58} In this population, information regarding the course of pregnancy often is anecdotal or comes from large, observational studies. As the surgical and interventional options improve, there may be different problems that potentially will arise during pregnancy.

Congenital heart diseases that may remain unrepaired seen in the adult patient include atrial septal defects, ventricular septal defect, patent ductus arteriosus, and Ebstein's anomaly (Table 8). Unrepaired complex cyanotic congenital heart disease rarely presents in adults. These patients will usually have undergone palliation or, more often, repair. Although they have had a physiologic (but not necessarily anatomic) correction or repair as a child, residual heart disease and/or surgical sequelae may persist into childbearing age. Residual problems postoperatively may be related entities that were not corrected by surgery whereas sequelae are complications from surgery.⁵ These may be manifest by tachyarrhythmias, heart block, valvular stenosis or insufficiency, ventricular dysfunction, or vascular abnormalities.^{5, 58, 59} The type of surgery and subsequent cardiac status need to be thoroughly assessed and treated before conception. Pregnancy in a woman with repaired or unrepaired congenital heart disease in the presence of secondary pulmonary hypertension is contraindicated. Pulmonary hypertension is associated with a 50% maternal mortality.¹⁷

Table 8. Potential complications of unrepaired congenital heart disease in pregnancy

Alterations in maternal hemodynamics, effects of maternal medication, and maternal cyanosis all directly affect fetal outcome. Maternal cyanosis is associated with higher incidence of abortion, still birth, and small-for-gestational-age babies.⁵⁹ In addition, the offspring of women (or men) with congenital heart disease are at increased risk for congenital heart disease.^{34, 60} Studies have shown an increased incidence of between 3.7% and 16.1%.^{34, 58, 60, 61} The father with a history of congenital heart disease confers a risk estimated to be from 2.1% to 14%.^{34, 58} A trend toward higher risk was demonstrated if the mother had a pulmonary or aortic outflow heart lesion.³⁴ Fetal echocardiography, optimally performed at 22 weeks' gestation, can identify most major cardiac malformations to help anticipate and treat problems in the neonatal period.⁶² Fetal echocardiography has been shown to detect major congenital cardiac anomalies in the fetus.⁶¹

Atrial septal defect

Atrial septal defect is one of the most common congenital heart lesions found in adults. If undetected or unrepaired during childhood, a secundum-type defect is more common that a primum or sinus venous type of defect.⁵⁸ The secundum atrial septal defect usually persists or enlarges in the region of the fossa ovalis. This defect is more common in females, and mitral valve prolapse is often seen. The sinus venous defect is located at the junction between the upper portion of the intraatrial septum and the point of origin of the superior vena cava and commonly is associated with partial anomalous pulmonary venous drainage. The ostium primum defect usually is detected and closed during childhood; however, after surgery a shunt may persist and often is associated with cleft mitral valve, which can be regurgitant in adults even after valvular repair.

The theoretical risk of an uncorrected atrial septal defect during pregnancy would be volume overload, which would further enlarge the right atrium and ventricle.^{17, 58} Theoretically, in any of the shunt lesions complicated by pulmonary hypertension, when systemic blood pressure decreases to less than that of the right-side pressure, there could be shunt reversal and cyanosis.¹⁷ Atrial septal defects complicated by severe pulmonary hypertension usually are detected before pregnancy and constitute a contraindication to pregnancy. A woman with an unrepaired atrial septal defect prescribed prolonged bed rest for obstetric reasons requires anticoagulation prophylaxis for deep venous thrombosis, because she is at risk for a paradoxical embolus. In one study of 80 patients there was a higher incidence of cesarean section and need for medical therapy for women with unreparied atrial septal defects compared with a postoperative population.⁶³ Atrial septal defects are currently closed by catheter-based devices. Pregnancies should be delayed 6 months after the procedure to allow for endothelialization of the device.

Atrial septal defects without associated pulmonary hypotension that have been closed may not constitute a risk to the patient and do not necessitate antibiotic prophylaxis.³⁰ The woman with residual pulmonary hypertension may not tolerate the increased blood volume of pregnancy. The risk of atrial arrhythmia may persist despite previous surgery.

Ventricular septal defect

The ventricular septal defect is the most common congenital heart disease lesion identified at birth; however, it is less common in adults. The defect may close spontaneously within the first 5 years of life. Uncorrected ventricular septal defects are less often associated with pulmonary hypertension, and other congenital lesions may be present. The most clinically significant associated defect is aortic regurgitation, in which the aortic leaflet prolapses into a membranous ventricular septal defect in an attempt to close the defect.⁵⁸ When diagnosed in adults, this is an indication for closure of the ventricular septal defect. An indication for closure would be increasing pulmonary artery pressure. This is a high-risk lesion for endocarditis patients who generally require antibiotic prophylaxis, which is optional for an uncomplicated vaginal delivery.³⁰

After closure of the ventricular septal defect, the patient may have residual shunting from multiple muscular defects, which all may not have been closed during surgery. Residual shunting or pulmonary hypertension can be detected on examination and confirmed by Doppler echocardiography during pregnancy. After surgical closure, pregnancy is not of increased risk if pulmonary pressures are normal; however, it is of markedly increased risk if pulmonary hypertension is present (see Eisenmenger's syndrome).¹⁷

Patent ductus arteriosus

When diagnosed during childhood, a patent ductus arteriosus is usually ligated. It rarely has been detected during adulthood. Elevation of pulmonary artery pressure and potential reversal of the shunt with profound systemic hypotension pose the same risks as do septal defects.⁵⁸ Previous repair without another congenital lesion, normal pulmonary pressures, and preservation of left ventricular function usually do not impact the course of pregnancy.

Eisenmenger's syndrome

Eisenmenger's complex is the hemodynamic consequence of a shunt lesion. Eisenmenger's syndrome occurs when an intracardiac shunt results in severe pulmonary vascular disease, increasing right ventricular pressure and causing right-to-left shunting of deoxygenated blood. The patient becomes cyanotic and experiences digital clubbing and polycythemia. Pregnancy is contraindicated in women with Eisenmenger's syndrome and associated pulmonary hypertension, which confers a maternal mortality rate up to 50%.^{17, 58} A recent series compiling experience from three referral centers found a maternal mortality of 27%.⁶⁴ During pregnancy, right ventricular enlargement may result in heart failure or arrhythmia. Right-to-left shunting may increase, thus worsening hypoxemia.⁶⁵ For women presenting in the first trimester of pregnancy, termination should be considered for the sake of maternal health. Later in pregnancy, termination can pose substantial risk and should be monitored carefully.⁵⁹

Pregnant women with Eisenmenger's syndrome should limit their physical activities, avoid the supine position, especially late in pregnancy, and possibly undergo prophylactic anticoagulation.⁶⁶ At the time of labor and delivery, there should be placement of hemodynamic monitoring to closely monitor the fluid status and intracardiac pressures.^{67, 68} Oxygen saturation should be monitored, and oxygen monitoring should be continued through labor and delivery and into the postpartum period.⁶⁶ The risk to the mother appears to be increased with cesarean section.⁶⁹ The fetal mortality can exceed 40%, even if the mother survives. Prematurity, small size, and low birth weight have been associated with the severity of maternal cyanosis.^{59, 70}

Coarctation of the aorta

Coarctation of the aorta involves a focal narrowing of the distal aorta arch or descending aorta, typically after the left subclavian, and usually is diagnosed during childhood. In adults, it can be complicated by hypertension, aortic dissection, and arteritis.⁵⁸ It is most often associated with a bicuspid aortic valve, ventricular septal defect, or patent ductus arteriosus. Coarctation of the aorta is associated with aneurysms of the circle of Willis, which may manifest as an intracranial hemorrhage. After childhood repair, a woman who wishes to conceive should be evaluated for significant restenosis (gradient >20 mmHg). After surgical repair, patients often require antihypertensive medication, which also should be assessed before conception. Hypertension may worsen during pregnancy and preeclampsia may occur.^{71, 72} Theoretically, in the setting of an unrepaired coarctation of the aorta, there is a question about whether uteroplacental perfusion is adequate. There have been reports of aortic dissection during pregnancy.⁷¹

Ebstein's anomaly

Ebstein's anomaly is characterized by a malformed, elongated tricuspid valve with distal displacement of the septal leaflet of the valve into the right ventricle. There is atrialization of the right ventricle by the downward placement of the tricuspid valve and the extent of viable right ventricular tissue remaining determines the patient's functional capacity. In women of childbearing age who are asymptomatic, it is usually a less severe form of the anomaly. Tricuspid regurgitation is commonly seen, and there may be an associated atrial septal defect or patent foramen ovale. Cyanosis can occur in adults and can worsen with exercise, fatigue, or exposure to cold (Table 8).

Tetralogy of Fallot

Tetralogy of Fallot is the most common cyanotic congenital heart disease. It is a complex cardiac defect that includes a large ventricular septal defect (malignment type), infundibular pulmonic stenosis, right ventricular hypertrophy, and an overriding aorta.⁵⁸ The woman with an unrepaired tetralogy of Fallot may have bidirectional shunting through the ventricular septal defect, and the severity of cyanosis could increase with a dramatic decrease in systemic vascular resistance or systemic blood pressure after hemorrhage or profound vasodilatation.^{17, 58} As the expected decrease in systemic vascular resistance occurs throughout pregnancy, there is increased right-to-left shunting, and arterial oxygen blood saturation decreases. Prolonged Valsalva maneuvers, such as those performed during the second stage of labor, may further decrease systemic blood flow, thus favoring right-to-left shunting and worsening cyanosis.

A woman who has undergone correction and has mild residual hemodynamic abnormalities, such as tricuspid regurgitation, pulmonic stenosis, or pulmonic regurgitation, should tolerate pregnancy well.^{17, 73} Patients with tricuspid regurgitation and right ventricular volume overload, may experience right ventricular failure with pregnancy. It is important to evaluate these women with Doppler echocardiography to assess baseline pulmonary pressures and valvular abnormalities before conception. Significant pulmonary insufficiency and/or right ventricular outflow tract obstruction cause right ventricular dilatation and dysfunction. This hemodynamic abnormality is strongly associated with supraventricular and ventricular arrhythmias.⁷⁴ There is a long-term risk for tachyarrhythmia and bradyarrhythmias postoperatively; therefore, Holter monitoring should be part of the preconception assessment and repeated during pregnancy if symptoms of palpitations, near-syncope, or syncope arise. Antiarrhythmic medications may need to be continued throughout pregnancy. Limited data are available regarding the use of antiarrhythmic agents during pregnancy, although case reports have been performed with pregnancies in the setting of nearly every commonly used agents (Table 3).

A large, observational report was made of women with Ebstein's anomaly who have successfully undergone pregnancy.⁷⁵ The outcome correlated with preconception maternal cardiac status. It was expected that tricuspid regurgitation would increase during pregnancy and the right ventricle would enlarge and possibly fail. Cyanosis may appear for the first time as systemic blood pressure decreases, promoting right-to-left shunting through the atrial septal defect or patent foramen ovale. These patients may have an accessory bypass tract, as seen in the Wolff-Parkinson-White syndrome, resulting in a supraventricular tachycardia that may first occur during pregnancy.⁷⁵ Women may not have symptoms and complete pregnancy successfully. There are limited data available regarding pregnancy after tricuspid valve reconstruction, but the risk for complications during pregnancy depend on the amount of residual tricuspid regurgitation, right ventricular function, and presence of arrhythmias. Tricuspid regurgitation may increase with prolonged Valsalva maneuver, as performed in the second stage of labor.

Complex cyanotic congenital heart disease

The woman of childbearing age born with complex cyanotic congenital heart disease (which includes tricuspid stenosis atresia,^{76, 77} double-outlet right ventricle,^{78, 79} single ventricle,⁸⁰ transposition of the great arteries,^{81, 82} or a variation of these entities) most likely has undergone surgical palliation or repair.⁸³ There have been case reports of women born with these defects who have had successful pregnancies.^{56, 83} The likelihood of an uncomplicated pregnancy is associated with normal or near-normal pulmonary artery pressures, normal systemic ventricular function, and absence of cyanosis.^{56, 83} Electrophysiologic sequelae of surgery may include bradyarrhythmias, heart block, supraventricular arrhythmias, or ventricular arrhythmias and necessitate continuation of antiarrhythmic therapy throughout the pregnancy.

Women born with tricuspid atresia may have undergone a Fontan procedure in which a conduit is placed to direct venous blood into the pulmonary artery. Although it has been shown that such patients have a subnormal response to exercise and limited cardiac reserve, there have been reports of successful pregnancies.⁸⁴ There are limited reports of complications of pregnancy in women after a Fontan surgery. Potential complications include atrial fibrillation/flutter, peripheral edema, hepatomegaly, and ascites.⁸⁵

Transposition of the great arteries

D-Transposition of the great arteries results in the aorta arising from the right ventricle and the pulmonary artery from the morphologic left ventricle. This was repaired historically by an atrial switch procedure to redirect incoming venous flow to the appropriate ventricle referred to as the Mustard or Senning procedure. Women currently nearing childbearing age will have undergone the arterial switch procedure (Jatene) to reattach the great vessel to the appropriate ventricle and reimplantation of the coronary arteries. Few pregnancies been reported in survivors of the arterial switch procedure surgery. After the Mustard or Senning repair, there are two clinical issues pertinent to pregnancy. First is whether the morphologic right ventricle, acting as the systemic ventricle, can withstand the additional volume load of pregnancy and, once dilated, whether it will return to its original size and function after pregnancy. Second, arrhythmias commonly occur years after the atrial switch operation and may cause complications such as junctional rhythms with the loss of sinus mechanism, atrial fibrillation, and heart block. Normal functional capacity, sinus rhythm, and an intact repair contribute to a favorable outcome of pregnancy.^{81, 82} A registry in the Netherlands reported 28 patients with 49 (71%) completed pregnancies.⁸¹ There were 17 spontaneous miscarriages (25%). Arrhythmias occurred in 54% of the 11 patients with cardiac complications. Medications were most often administered for arrhythmias. A decline in NYHA functional class occurred in 77% but only two patients developed heart failure. This highlights an important concern regarding future pregnancies and the need for full evaluation prior to successive pregnancies. Pregnancy after arterial switch for transposition should be uncomplicated and feasible but limited data are available at the present time.⁸⁶

L-transposition of the great vessels is characterized by the aorta arising from the morphologic right ventricle which receives blood from the left atrium and the pulmonary artery arising from a morphologic left ventricle.⁵⁸ A woman may reach adulthood without known cardiac problems. Cardiac complications of L-transposition of the great arteries include heart block, systemic, or A-V valve regurgitation or systemic ventricular failure. There is a concern whether the impaired systemic ventricle could accommodate the volume load of pregnancy. A report of 22 patients having 60 pregnancies noted congestive heart failure during pregnancy related to severe systemic A-V valve regurgitation.⁸⁷ Other reported complications included toxemia, endocarditis, cyanosis, cerebrovascular accident, and myocardial infarction in a patient with anomalous coronary artery anatomy.^{87, 88} Heart block may limit cardiac adaptation to the hemodynamic changes of pregnancy.⁸⁸

Preexisting aortic disease in pregnant women is rare and most often occurs in the setting of a bicuspid aortic valve or the Marfan syndrome.⁸⁹ It has been previously suggested in the medical literature that women may be more susceptible to aortic dilation dissection and rupture in the last trimester of pregnancy, however, more recent information disputes this finding. A study did not find an increased incidence of aortic disease in women of childbearing age who had experienced pregnancy.⁹⁰ The hormonal changes mediate monthly muscle relaxation within the aortic wall.

Marfan syndrome

Marfan syndrome is a rare disorder of connective tissue that has autosomal dominant genetic transmission with a high degree of penetrance. Clinical manifestations of the syndrome include skeletal, ocular, pulmonary, and cardiovascular abnormalities. Aortic dilatation may be present in childhood, first manifesting in young adulthood as aortic dissection, aortic rupture, or aortic valve regurgitation.^{90, 91, 92, 93, 94} Aortic dissection occurs when there is a sudden tear separating the intima from the adventitia. There often are associated, marked, myxomatous changes of the mitral valve resulting in prolapse and mitral regurgitation. Nearly all patients with Marfan syndrome have myxomatous changes of the aortic and mitral valves.

A woman with Marfan syndrome should consider several issues when considering pregnancy.^{91, 92, 93, 94} There is a 50% risk that her offspring will inherit the syndrome, which necessitates preconception genetic counseling. There is an increased risk for aortic rupture and dissection in the third trimester.^89,92 Structural changes in the aortic wall are hormonally mediated during pregnancy, because high estrogen levels may interfere with collagen deposition in the media and predispose to aneurysm formation or dissection.^{6, 92} It has been shown that aorta in women with Marfan syndrome are specifically at risk of complication if the aorta is greater than 45mm.⁹⁴ Therefore, it is recommended that patient be counseled to avoid pregnancy if she has an aortic diameter exceeding 40 cm, as measured by echocardiography.^{93, 94} Noninvasive imaging with transesophageal echocardiography, computed tomography, or magnetic resonance imaging may be used to evaluate such patients for preconception aortic size. Late during pregnancy, if aortic pathology is suspected, transesophageal echocardiography eliminates the risk of ionizing radiation and can be performed at the bedside to visualize the thoracic aorta and diagnose, if it is a dissection. Obstetric complications including premature delivery have been described.⁹³

Medical therapy of the aortic dissection includes intravenous beta-adrenergic blockade and sodium nitroprusside infusion. Sodium nitroprusside is a potent vasodilator used in pregnancy for aortic dissection or hypertensive crisis unresponsive to conventional therapy. This drug is metabolized to cyanide and thiocyanate and crosses the placenta, raising the concern of its potential fetal toxicity. In animal studies, fetal deaths occurred during administration of very high (25 mg/kg per minute) doses, but no such effects were observed with standard therapeutic doses (less than 10 mg/kg per minute). Therefore, maternal cyanide levels need to be monitored during extended therapy. Adverse maternal effects include flushing, hypotension, and cyanide toxicity. Surgical intervention is indicated for ascending aortic dissection, as it is in the nonpregnant patient. Prophylactic use of beta-adrenergic blockade in the patient with Marfan syndrome has been recommended to prevent dilation and should be continued during pregnancy.

Women with Turner's syndrome have bicuspid aortic valves and are at risk for aortic dilatation and dissection during pregnancy but few data are available regarding their management.⁹⁵ Also, at risk for enlargement are woman with bicuspid aortic valves and they, too, may benefit from prophylactic beta-blockade during pregnancy to prevent further enlargement.⁸⁹

Although rare, women of childbearing age may have acquired myocardial disease before pregnancy. It is critical to evaluate women with a history of any form of myocardial disease before conception. There may be several causes of myocardial disease, with each requiring a specific clinical approach. Ischemia or myocardial infarction caused by coronary artery disease, although uncommon, may increase in prevalence as mothers become older and the childbearing years become extended. Especially at risk are women with familial hypercholesterolemia or diabetes mellitus.⁹⁶ Intrinsic systolic dysfunction caused by a previous viral myocarditis is the most likely etiology in this age group, hypertrophic cardiomyopathy is less common, and it is rare that a woman who has undergone cardiac transplantation will undergo preconception evaluation. Currently, women of childbearing age may have received chest radiation therapy and/or cardiotoxic chemotherapy for a childhood malignancy and have residual cardiac dysfunction with impaired functional reserve.

Pregnancy after peripartum cardiomyopathy has become an important clinical issue. Although clinical improvement may be apparent there is a risk of recurrence in successive pregnancies.^97,98,99 One study recommended a 3-year interval after complete recovery.⁹⁸ In a national survey, heart failure was more common in patients without complete normalization of ventricular function.⁹⁷ Other etiologies of cardiopathy may be associated with better outcomes of subsequent pregnancies.⁹⁹

Women with a history of cardiomyopathy require careful evaluation and counseling before pregnancy. Such women may be able to sustain successful pregnancies, but preconception counseling and evaluation must anticipate the effects of pregnancy on baseline cardiac function and whether pregnancy will impact the patient's functional capacity and her future physical ability to care for the child after birth and as the child grows.

Coronary artery disease is rare in women of childbearing age. However, coronary disease may be caused by long-standing diabetes mellitus, hypercholesterolemia, previous thoracic radiation therapy, smoking, or oral contraceptive use while smoking. When coronary artery disease is suspected during pregnancy or in the preconception evaluation of a woman with a history of coronary artery disease, stress echocardiography is a safe diagnostic modality. The stress component may be limited to a specific heart rate during pregnancy, but combining cardiac ultrasound with submaximal exercise improves the diagnostic yield. Radionuclide agents should not be used during pregnancy unless absolutely necessary. If cardiac catheterization is deemed necessary for a clinical indication, it should be performed with abdominal shielding during pregnancy.

Angina and myocardial infarction rarely occur during pregnancy.¹⁰⁰ In women with risk factors, the evaluation of chest pain during pregnancy must consider coronary artery disease as the cause. Previously quiescent coronary artery disease may first become symptomatic during pregnancy. Coronary artery spasm has been postulated as the mechanism of angina in the presence of normal coronary arteries, although thromboembolic events may play a role because the pregnant patient is hypercoagulable. Coronary artery dissection has also been described as an etiology.¹⁰¹ The medical management of symptomatic coronary artery disease during pregnancy should be similar to that in the nonpregnant patient. Beta-adrenergic blockers, specifically the selective agents such as atenolol and metoprolol, are indicated for ischemic disease, hypertension, and arrhythmia and should be continued throughout pregnancy. Nitrates should be reserved for symptomatic control of angina because of their potential side effects of headache, dizziness, weakness, and postural hypotension. Calcium-channel blockers, such as nifedipine, verapamil, diltiazem, and amlodipine, may also be used, especially if there is vasospastic component to the angina. These agents may cause significant hypotension, peripheral edema, and constipation. Verapamil and diltiazem also are used for the treatment of supraventricular arrhythmias. Low-dose aspirin may be tolerated, although there are risks of bleeding during pregnancy and premature closure of the ductus arteriosus near term. Intravenous heparin can be used in the patient with unstable angina. There have been anecdotal, rare reports of percutaneous transluminal coronary angioplasty and coronary artery bypass surgery performed during pregnancy.^{29, 38}

Myocardial infarction has been reported either during pregnancy or during the postpartum period.^{100, 102} Women with myocardial infarction tend to be older, and there has been an association with preeclampsia. Other case reports suggest that coronary artery thromboembolism may be the mechanism for the infarct. Medical therapy should be the same as in the nonpregnant state, although thrombolytic therapy should be avoided and direct angioplasty is preferred.¹⁰³ Aspirin should be administered.

During labor, women with symptomatic ischemic heart disease should continue their medication, unless contraindicated, and should receive supplemental oxygen. Nitrates and the beta-adrenergic blocker esmolol may be administered intravenously. Vaginal delivery is preferred; cesarean section is reserved for obstetric indications. There have been case reports of women who have had successful pregnancies after myocardial infarction¹⁰⁴ and even anecdotal experience with pregnancy after coronary artery bypass surgery. After bypass surgery, aspirin is continued to maintain graft patency. Lipid-lowering medications, such as nicacin, gemfibrozil, lovastatin, pravastatin, simvastatin, and atorvastatin, should not be continued during pregnancy.¹⁰⁵ Normal functional capacity, the absence of angina, and normal ventricular reserve are the best predictors of pregnancy outcome.

Left ventricular systolic dysfunction

Women with left ventricular systolic dysfunction usually have had viral myocarditis; other causes include previous peripartum cardiomyopathy,¹⁰⁶ severe hypertensive disease, and valvular heart disease. It is crucial to evaluate these patients before conception to assess their functional reserve. In women with a history of myocarditis, if the cardiac function appears normal at rest and there is a normal response to exercise off medications, a successful pregnancy may be possible. Historical information regarding New York Heart Association functional class is important because patients with normal functional capacity are most likely to sustain successful pregnancies. Pregnancy is contraindicated in women with functional class III or IV disease, specifically those who have symptoms of congestive heart failure occurring with minimal activity or at rest.⁹⁷ The dilated ventricles with systole dysfunction can expect to enlarge further with pregnancy, and it is unknown whether the heart will revert to normal size and function after the pregnancy is over, as is expected in women with normal hearts. Preconception evaluation includes assessment of prescribed medications; for example, ACE inhibitors, such as captopril, fosinopril, benazepril, and enalapril, are contraindicated during pregnancy and should be discontinued either before conception or as soon as possible in the first trimester. However, abrupt discontinuation of this medication may worsen the patient's clinical status. Hydralazine is an alternative therapy for vasodilation during pregnancy and has been used for hypertension therapy during pregnancy; its risks include reflex tachycardia and hypotension.

Augmented preload during pregnancy puts the patient with cardiomyopathy at risk for pulmonary edema, which most often occurs after week 20 of gestation. Therefore, limitation of dietary salt intake, restriction of physical activity, and digoxin and hydralazine should be used when clinically indicated. Digoxin can be used during pregnancy to improve systolic function, although the volume of distribution is increased; therefore, higher levels may be required. Diuretic therapy should be reserved for congestive heart failure because of the risk for electrolyte loss and excessive volume contraction. Thiazide diuretics may be used, but in women with pulmonary edema, furosemide may be required. Beta-adrenergic blockers at low doses also are important to institute once pulmonary edema as resolved. Pregnancy is a hypercoagulable state, and prophylactic anticoagulation may be considered in the woman who is not ambulatory. When severe pulmonary edema occurs, intravenous inotropic agents, such as dopamine, dobutamine, or amrinone, may be required. These agents may cause tachycardia and ventricular ectopy. They are used in a critical care setting often in conjunction with hemodynamic monitoring (Swan-Ganz catheter). Amrinone, a vasodilator and inotropic agent, is administered intravenously. The major risks are thrombocytopenia, arrhythmia, and hypotension. These patients are at risk for atrial fibrillation or ventricular arrhythmias. Amiodarone, a potent antiarrhythmic with a prolonged half-life is often needed. It has been associated with maternal and fetal thyroid dysfunction and with maternal pulmonary and dermatologic complications.

During labor and delivery, invasive hemodynamic monitoring helps to assess intracardiac filling pressures and to treat efficiently. The impaired ventricle is dependent on adequate preload; however, excessive preload results in pulmonary edema. These fluids shifts may occur after delivery, so the monitor should remain in place for 24–48 hours.

Left ventricular diastolic dysfunction

A hypertrophic cardiomyopathy may be present in women of childbearing age; in this disorder, the heart muscle is thickened and has limited compliance.^{9, 107, 108} It may manifest as asymmetric hypertrophy of the septum or as a global, left ventricular hypertrophy. Hypertrophy of the ventricle may be seen as a result of long-standing hypertension but in this age and group may be a primary problem.⁸ In idiopathic hypertrophic subaortic stenosis with asymmetric septal hypertrophy there may be associated mitral regurgitation as the mitral valve moves against the septum during systole. Women with this disorder require adequate volume; therefore, the increased preload of pregnancy does not usually pose a problem for these women. Theoretically, the decrease in afterload that occurs with systemic vasodilation in pregnancy may be more problematic, although this has not been seen clinically. Arrhythmias may occur and atrial fibrillation with the loss of the atrial component of ventricular filling may result in pulmonary edema.¹⁰⁸ Although these women present with heart failure and excessive volume overload, in this setting inotropic agents such as digitalis should be avoided.¹⁰⁷ Sympathomimetic agents may increase heart rate, further decreasing outflow from the heart. Therefore, tocolytic therapy must be used carefully in this patient population. The second stage of labor, because of the Valsalva maneuver, should be avoided. Women who require beta-adrenergic blockade therapy to prevent the risk of sudden death should be counseled during preconception evaluation regarding the fact that it is important to continue this medication throughout pregnancy.^{107, 109}

A woman with a symptomatic cardiomyopathy many years before pregnancy may have undergone cardiac transplantation. Patients of this age require transplantation because of congenital heart disease, hypertrophic cardiomyopathy, postpartum cardiomyopathy, or the presence of a cardiac tumor.^{109, 110, 111, 112} There have been case reports of successful deliveries after cardiac transplantation and also after combined heart and lung transplantation.^{109, 111, 112} The transplanted heart is denervated, although normal contractility is seen. The ventricle may be functioning normally, and preconception evaluation should assess cardiac function both anatomically and physiologically with stress testing. The absence of rejection needs to be established firmly in these patients before pregnancy. Blood pressure should be well controlled throughout pregnancy, because there are reports of increased blood pressure in these patients.^{109, 111} Immunosuppressive agents must be continued, although fetal complications have been reported with prednisone and cyclosporine.^{113, 114} Cyclosporine levels must be monitored to avoid toxicity.^{113, 114} Periodic assessment for the presence of rejection with no myocardial biopsy may be required. All of these issues should be discussed in preconception counseling. Breastfeeding is discouraged in women using immunosuppressive agents.¹¹³

In conclusion, preconception counseling facilitates successful pregnancy outcomes in women with preexisting cardiovascular disease. Although some women with severe, debilitating forms of cardiovascular disease may be further compromised by the hemodynamic changes of pregnancy, most can sustain pregnancy. Successful outcome often requires a multidisciplinary strategy formulated by the obstetrician, cardiologist, and anesthesiologist, who can anticipate, treat, and even prevent cardiovascular complications.