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CURRENT Diagnosis & Treatment in Cardiology > Chapter 31. Cardiovascular Disease in Pregnancy >

Essentials of Diagnosis

  • Pregnancy.
  • History of heart disease.
  • Symptoms and signs of heart disease.
  • Echocardiographic or other objective evidence of heart disease.

General Considerations

Cardiovascular disease occurs in approximately 1% of pregnancies, but the incidence is increasing due to improved prognosis of women with congenital heart disease and a trend toward older maternal age. The unique hemodynamic changes associated with pregnancy make diagnosis and management of heart disease in pregnant patients a challenge to the physicians, who must consider not only the patient but also the risks to the fetus.

In general, the normal hemodynamic changes associated with pregnancy are well tolerated by those who have a normal cardiovascular system, valvular regurgitation, and left-to-right intracardiac shunts. On the other hand, the highest maternal and fetal morbidity and mortality is seen with severe obstructive valvular lesions, severe aortic disease (dilated thoracic aorta or uncorrected coarctation), New York Heart Association (NYHA) class III or IV heart failure, uncontrolled hypertension, and cyanotic congenital heart disease. As a rule, spontaneous vaginal delivery, often with use of vacuum extraction or forceps to facilitate stage 2 of labor to avoid the hemodynamic stress associated with pushing, is preferred. Cesarean section, with few exceptions, should be reserved for obstetric indications.

Stout KK et al. Pregnancy in women with valvular heart disease. Heart. 2007 May;93(5):552–8. [PMID: 16905631]

Cardiovascular Physiology of Normal Pregnancy

Normal pregnancy is accompanied by significant physiologic changes, although underlying mechanisms remain virtually unknown (Table 31–1). The normal signs and symptoms associated with pregnancy, such as shortness of breath, fatigue, and exercise intolerance, may obscure the diagnosis of heart disease. The clinician must, therefore, have a thorough knowledge of these normal changes and the aspects of the history and physical examination that suggest the presence of heart disease.

Table 31–1. Cardiovascular Changes in Normal Pregnancy.

  First Trimester Second Trimester Third Trimester At Term
Blood volume + + + + + + 30–50%
Heart rate + + + + + (+) 15–20 beats/min
Stroke volume + + + (+) +  
Cardiac output + + + (+) + 30–50%
Systolic blood pressure No change 5–10 mm Hg mid pregnancy
Diastolic blood pressure – –
Pulse pressure + ++ +
Systemic vascular resistance – – – – –  
Pulmonary vascular resistance – –  
Left ventricular end-diastolic pressure + + + No change  
Venous compliance and volume + + + +  
Red blood cell mass + + + 15–20%

Data from Fujitan S. Crit Care Med. 2005;33:S354.

Blood Volume

The increase in maternal blood volume begins as early as the sixth week of pregnancy, peaks at approximately 32 weeks of gestation, and stays at that level (40–50% higher than pregestational levels) until delivery. The plasma volume shows a more rapid and significant rise than the red blood cell mass, accounting for the appearance of physiologic anemia during pregnancy. The increased blood volume is maintained until after delivery, when a spontaneous diuresis occurs. At the same time, there is an increased venous return due to the relief of vena caval compression after delivery. These rapid postpartum changes in blood volume are critical for patients with underlying heart disease.

Cardiac Output

One of the most significant changes during pregnancy is the increase in cardiac output, which begins to rise during the first trimester and peaks around the twenty-fifth week of gestation and then levels off. Total cardiac output increases up to 50% over pregestational levels. Cardiac output is the product of stroke volume and heart rate. During the early part of pregnancy, the increase in cardiac output is predominantly the result of an increase in stroke volume, augmented by increased intrinsic myocardial contractility. Numerous studies have shown a gradual increase in left ventricular systolic function attributed to left ventricular afterload reduction due to the low-resistance runoff of the placenta. The rise in left ventricular systolic function begins in early pregnancy, peaks in the twentieth week, and then remains constant until delivery. As pregnancy advances, heart rate increases and stroke volume mildly decreases. The increased cardiac output in late pregnancy is maintained because of the increased heart rate.

A unique aspect of pregnancy is the hemodynamic changes induced by a change in a patient’s position. When the patient is in the supine position, the gravid uterus induces profound mechanical compression of the inferior vena cava, decreasing venous return to the heart, and thus, cardiac output. A change from the supine to the left lateral position results in a 25–30% increase in cardiac output because of an increase in stroke volume.

Intravascular Pressures and Vascular Resistance

Systolic and diastolic pressures drop during pregnancy. A small decrease in systolic blood pressure begins in the first trimester, peaks at midgestation, and returns to near prepregnancy levels at term. The diastolic blood pressure decreases more than the systolic blood pressure, due to a significant fall in systemic vascular resistance, and results in a wider pulse pressure. The systemic blood pressure increases during pregnancy with the patient’s age and parity. It also varies with the patient’s position. The highest levels are recorded early in the pregnancy when the patient is upright, and lowest when she is supine. During the latter part of pregnancy, the effect of position on systemic blood pressure depends on the relative degrees of inferior vena cava and aortic compression. Total vascular resistance, including both the systemic and the pulmonary, decrease during pregnancy. The mechanism for the fall in resistances is poorly understood but is attributed to the low-resistance circulation of the pregnant uterus and to hormonal changes associated with pregnancy.

Fujitani S et al. Hemodynamic assessment in a pregnant and peripartum patient. Crit Care Med. 2005 Oct;33(10 Suppl):S354–61. [PMID: 16215359]

Etiology & Symptomatology

Congenital Heart Disease

Because the medical and surgical treatment of uncorrected or surgically corrected congenital heart diseases has improved, more women are surviving into adulthood and may become pregnant. Cardiac complications occur in approximately 11% of these patients, most commonly due to heart failure (in 4.8%) and arrhythmias (in 4.5%). Maternal mortality primarily occurs in women with Eisenmenger syndrome. Obstetric complications are not increased, except in cases of hypertension and thromboembolic disease (2%). Premature delivery occurs in about 16%, and children small for gestational age are also common. Overall, offspring mortality is around 4%. The risk of recurrence of congenital malformations in the offspring depend on the type and range from 0.6% to 8%.

Only a few conditions place a patient at a high risk to advise against pregnancy (Table 31–2). High-risk patients with severe cyanotic congenital heart disease, marked decreased functional capacity, or Eisenmenger syndrome should be advised against pregnancy.

Table 31–2. High-Risk Conditions That Warrant Advice against Pregnancy.

Condition Maternal Risk Fetal Risk
1.   Cyanotic congenital heart disease 4–34% MI/stroke/death 12–40% miscarriage
2.   Eisenmenger syndrome 35% MI/stroke/death 30% miscarriage
3.   Severe pulmonary hypertension (> 75% of systemic blood pressure) 30–40% death 10% fetal loss
4.   NYHA class III/IV symptoms 10–56% death 30% fetal loss
5.   Severe symptomatic obstructive valvular lesions 56–78% CHF or pulmonary edema 11% death
33–66% preterm delivery
6.   Marfan syndrome with thoracic aorta > 4.0 cm 11–50% risk of dissection 50% risk of inheriting the syndrome
4–20% risk of fetal/neonatal death
7.   Loeys-Dietz syndrome 9% death in non-pregnant with aorta < 4.5 cm 50% risk of inheriting the syndrome

Data from Crawford MH. Cardiology. 2001; Drenthen W. J Am Coll Cardiol. 2007;49:2303–2311; Hameed A. J Am Coll Cardiol. 2001;37:893–899; Silversides CK. Am J Cardiol. 2003;91:1382–1389; Elkayam U. J Am Coll Cardiol. 2005;46:223–230; Lind J. Eur J Obstet Gynecol Reprod Biol. 2001;98:28–35; Elkayam U. Ann Intern Med. 1995;123:117–122; Sliwa K. Lancet. 2006;368:687–693; Williams JA. Ann Thorac Surg. 2007;83:757–763.

Acyanotic Heart Disease

Atrial Septal Defect

Secundum atrial septal defect is the most common congenital cardiac abnormality encountered during pregnancy. Patients with uncomplicated atrial septal defects usually tolerate pregnancy with little problem. Patients may not be able to tolerate the acute blood loss that can occur at the time of delivery because of increased shunting from left to right caused by systemic vasoconstriction associated with hypotension. The incidence of supraventricular arrhythmias may increase in older pregnant patients, which may result in right ventricular failure and venous stasis leading to paradoxical emboli. Low-dose aspirin, once daily after the first trimester until delivery may help prevent clot formation. Pulmonary hypertension from an atrial septal defect usually occurs late in life, past the childbearing years. Bacterial endocarditis prophylaxis is not recommended. Vaginal delivery is preferred over cesarean section. Risk of occurrence in the offspring is about 2.5%.

Ventricular Septal Defect

Most isolated ventricular septal defects have closed by adulthood. Women with ventricular septal defects generally fare well in pregnancy if the defect is small and pulmonary artery pressure is normal. Congestive heart failure and arrhythmia are reported only in patients with decreased left ventricular systolic function prior to pregnancy. Endocarditis prophylaxis during delivery is not recommended.

Congenital Aortic Stenosis

This is most commonly caused by a congenital bicuspid aortic valve. The prevalence in the general population is 1–2% but may be as high as 9–21% in some families, where the condition appears to be autosomal dominant with reduced penetrance. The condition is usually more common in men (2:1 ratio). In patients with congenital aortic stenosis, the outcome during pregnancy depends on the severity of the obstruction. Pregnancy is usually well tolerated in mild-to-moderate aortic stenosis (aortic valve area [AVA] 1.0–2.0 cm2). Patients with severe aortic stenosis with a valve area of < 1.0 cm2 and mean transvalvular gradients greater than 50 mm Hg may experience an increased risk of complications (from 10% to 44%) and fetal morbidity is increased. The increased cardiac output and decreased systemic vascular resistance of pregnancy creates an additional hemodynamic burden in these patients. Syncope, cerebral symptoms, dyspnea, angina pectoris, and even heart failure may occur for the first time during pregnancy. The rate at which valve replacement is necessary after pregnancy is markedly increased. Ideally, balloon valvuloplasty or valve replacement should be performed before pregnancy in symptomatic patients with severe aortic stenosis. Valvuloplasty, if needed, is preferred over surgery during pregnancy. Hemodynamic monitoring during labor and delivery should be performed in patients with moderate to severe aortic stenosis. Endocarditis prophylaxis is not recommended for vaginal delivery. As part of the bicuspid aortic valve syndrome, the aortic root often will be dilated, evidence that the condition is not only a disease of the valve but of the connective tissue as well. When the aortic root is dilated there is an increased risk of aortic dissection during pregnancy, and such events have been reported when the aorta is greater than 40 mm, although the true incidence is unknown. Obtaining serial echocardiograms at least every 3 months to monitor progression of root dilatation appears prudent. The risk for the condition in the offspring is variable but at least 4%.

Pulmonic Stenosis

The natural history of pulmonic stenosis favors survival into adulthood even with severe obstruction to right ventricular outflow. Mild-to-moderate pulmonic stenosis (peak gradient < 50 mm Hg) usually presents no increased risk during pregnancy. Patients with severe pulmonic stenosis may occasionally tolerate pregnancy without the development of congestive heart failure. Vaginal delivery is tolerated well. Ideal treatment consisting of balloon valvuloplasty should be performed before conception but may be performed safely during pregnancy if necessary. The risk in the offspring is about 3.5%.

Coarctation of the Aorta

In uncomplicated coarctation of the aorta, pregnancy is usually safe for the mother but may be associated with fetal underdevelopment because of the diminished uterine blood flow. The blood pressure may decrease slightly, as during normal pregnancy, but still remains elevated. Maternal deaths in these patients are usually the result of aortic rupture or cerebral hemorrhage from an associated berry aneurysm of the circle of Willis. Patients with the greatest risk during pregnancy are those with severe hypertension or associated cardiac abnormalities, such as bicuspid aortic valves. Treatment consists of limitation of physical activity and maintenance of systolic blood pressure around 140 mm Hg for fetal circulation; -blockers are preferred and should be continued through delivery. Patients with severe uncorrected coarctation and poorly controlled hypertension should undergo cesarean section. Surgical treatment should be reserved for patients in whom complications develop, eg, aortic dissection, uncontrollable hypertension, and refractory heart failure.

Patent Ductus Arteriosus

Most patients with a patent ductus arteriosus undergo repair in childhood. A normal pregnancy can be expected in patients with small-to-moderate shunts and no evidence of pulmonary hypertension. Patients with a large patent ductus arteriosus, elevated pulmonary vascular resistance, and a reversed shunt are at greatest risk for complications during pregnancy. The decreased systemic vascular resistance associated with pregnancy increases the right-to-left shunt and may cause intrauterine oxygen desaturation. Patients in whom heart failure develops are treated with digoxin and diuretics. Closure of the patent ductus arteriosus may be done safely during pregnancy using a percutaneous ductal occluder device. The preferred mode of delivery is vaginal in most patients, with hemodynamic monitoring considered at the time of delivery. The risk of patent ductus arteriosus occurring in an offspring is about 4%.

Cyanotic Heart Disease

Tetralogy of Fallot

This is the most common cyanotic congenital heart disease found in pregnant patients. The syndrome consists of pulmonary stenosis, right ventricular hypertrophy, an overriding aorta, and a ventricular septal defect. The decrease in systemic vascular resistance, the increased cardiac output, and the increased venous return to the right heart augment the amount of right-to-left shunt and further decrease the systemic arterial saturation. Acute blood loss during postpartum hemorrhage is particularly dangerous because venous return to the right heart is impaired. The labile hemodynamics during labor and the peripartum period may precipitate cyanosis, syncope, and even death in surgically untreated women. Patients with uncorrected or partially corrected tetralogy of Fallot are advised against becoming pregnant because they have a high rate of miscarriages (12–40%) as well as a high risk of heart failure (15–25%); arrhythmias (5%) and stroke, myocardial infarction (MI), or death (4–34%). Patients who have had good surgical repair may anticipate successful pregnancies, although the risk of arrhythmias may be increased. Antibiotic prophylaxis is recommended for patients with uncorrected tetralogy of Fallot and those in whom prosthetic material has been placed within 6 months. The risk in the offspring is approximately 4%.

Eisenmenger Syndrome

This syndrome may occur due to several types of congenital heart disease and is characterized by systemic level pulmonary hypertension with right-to-left or bidirectional shunt with deoxygenation. The risk of maternal and fetal morbidity and mortality is so high that patients are advised against becoming pregnant. There is a 35% chance of MI, stroke, or death in the mother and almost 30% offspring mortality.

Surgically Corrected Congenital Heart Disease

The obstetric care of patients who have had surgical correction of a congenital heart disease requires an understanding of the type of surgical procedure, the sequelae, and the hemodynamic consequences. Although atrial flutter may occasionally develop following surgical closure, the successful closure of an uncomplicated atrial septal defect results in no increased maternal risk during pregnancy. Surgical closure of a patent ductus arteriosus that is not associated with pulmonary hypertension is also not associated with maternal complications during pregnancy. In pulmonary hypertension that develops before surgical closure, the decrease in the pulmonary vascular resistance may not be complete, and complications during pregnancy will depend on its severity. Correction of congenital pulmonary stenosis with either surgery or balloon dilatation that leaves little or no transvalvular gradient presents no difficulty to pregnant patients. Surgical correction of coarctation of the aorta with complete relief of the obstruction decreases the development of associated hypertension and the risk of aortic rupture during pregnancy. Successful repair of tetralogy of Fallot with little residual gradient across the pulmonary outflow tract and relief of the cyanosis should result, with careful management, in a normal pregnancy. Pregnancy after repair of complex congenital heart disease is increasingly encountered. In such patients, the outcome depends on the mother’s functional status, the type of repair, the sequelae, and the cardiovascular response to an increase in stress.

Drenthen W et al. Outcome of pregnancy in women with congenital heart disease: a literature review. J Am Coll Cardiol. 2007 Jun 19;49(24):2303–11. [PMID: 17572244]

Elkayam U et al. Valvular heart disease and pregnancy: part I: native valves. J Am Coll Cardiol. 2005 Jul 19;46(2):223–30. [PMID: 16022946]

Valvular Heart Disease

No randomized controlled trial data are available to guide decision making for pregnant women with valvular heart disease. However, many patients with valvular heart disease can be treated successfully through their pregnancy with conservative medical treatment, focusing on optimization of intravascular volume and systemic load. Ideally, symptomatic patients should be treated before conception. Drugs, in general, should be avoided whenever possible. Antibiotics for infective endocarditis prophylaxis for uncomplicated vaginal delivery are not indicated, unless a prosthetic valve was placed within 6 months. Although there is little supportive data, antibiotic prophylaxis is often given for complicated vaginal deliveries.

Mitral Valve Disease

Mitral Stenosis

Mitral stenosis is the most commonly encountered acquired valvular lesion in pregnancy and is almost always caused by rheumatic heart disease. Mitral stenosis may be first diagnosed during pregnancy and is the valvular disorder most likely to develop serious complications during pregnancy. Increased left atrial pressure and even pulmonary edema due to a decrease in diastolic filling time during the tachycardia of pregnancy may develop in women who were previously asymptomatic. In critical mitral stenosis, due to a large diastolic gradient (even at rest), any demand of increased cardiac output results in a significant elevation in the left atrial pressure and pulmonary edema. The most common symptoms include dyspnea, fatigue, orthopnea, and dizziness or syncope. Signs and symptoms of mitral stenosis may develop for the first time during pregnancy. The greatest danger is in late pregnancy and labor due to increased heart rate and cardiac output, blood volume expansion, and intensified oxygen demand. Mild-to-moderate mitral stenosis (mean diastolic pressure gradient less than 10 mm Hg) may be managed safely with the use of diuretics to relieve pulmonary and systemic congestion and -blockers to prevent tachycardia to optimize diastolic filling. Diuretics, -blockers, digoxin, or DC cardioversion for atrial fibrillation should be instituted in cases of hemodynamic compromise, taking into consideration maternal safety. Refractory cases and patients with severe mitral stenosis with heart failure prompt mechanical relief, either by percutaneous balloon valvuloplasty or surgery, preferably before conception if the valve is anatomically suitable. Patients with a history of acute rheumatic fever and carditis should continue receiving penicillin prophylaxis.

Mitral Regurgitation

Mitral regurgitation (most commonly due to mitral valve prolapse) in the absence of NYHA class III or IV heart failure symptoms is generally tolerated well during pregnancy, even if severe. The decrease in systemic blood pressure in pregnancy may reduce the amount of mitral regurgitation. Left ventricular dysfunction, if severe, may precipitate heart failure. Medical management includes use of diuretics; in rare instances, surgical management is necessary, preferably mitral valve repair, which is indicated for severe, acute regurgitation or ruptured chordae and uncontrollable heart failure symptoms. In the future, percutaneous mitral valve repair may be an option for severe, symptomatic mitral regurgitation during pregnancy.

Mitral Valve Prolapse

Mitral valve prolapse is the most common heart disease encountered in pregnancy. Patients without comorbidity, such as a connective tissue, skeletal, or other cardiovascular disorders, tolerate pregnancy. The click and murmur become less prominent during pregnancy. No special precautions for isolated mitral valve prolapse are required. Antibiotic prophylaxis is not recommended. The incidence of complications of the mitral valve prolapse (3%) is similar in pregnant and nonpregnant patients.

Aortic Valve Disease

Aortic Stenosis

Aortic stenosis in pregnancy is most commonly caused by a congenital bicuspid aortic valve (see previous section).

Aortic Regurgitation

Isolated chronic aortic regurgitation without left ventricular dysfunction is usually tolerated well. Even if patients are symptomatic, they can often be treated medically with salt restriction, diuretics, and vasodilators. The most common causes are rheumatic disease, bicuspid aortic valve, endocarditis, and a dilated aortic root. Surgery is only indicated for patients with refractory (NYHA class III or IV) symptoms. Acute aortic regurgitation is not well tolerated and should be regarded as a surgical emergency.

Pulmonic and Tricuspid Valve Disease

Pulmonic Valve Regurgitation

Pulmonic valve regurgitation may occur in isolation or in combination with other heart lesions. Isolated pulmonic regurgitation can be managed conservatively.

Tricuspid Valve Disease

Tricuspid valve disease may be congenital or acquired. Isolated tricuspid valve disease can be managed successfully with diuretics. Special care should be given to diuretic-induced hypoperfusion.

Prosthetic Heart Valves

Females with a prosthetic heart valve can usually tolerate the hemodynamic burden of pregnancy without difficulty. The function of the prosthesis can be evaluated and monitored throughout the pregnancy with noninvasive Doppler echocardiography. Two types of heart valves are available with their own distinct risks and advantages: tissue valves and mechanical prostheses. The main differences between the types are durability, risk of thromboembolism, valve hemodynamics, and effect on fetal outcome.

Tissue valves (bioprostheses) may be selected for a pregnant patient to avoid anticoagulation and risk of thromboembolism and should be considered in women of childbearing age who desire a pregnancy if there are no other indications for anticoagulation, and if the patient accepts the eventual need for replacement of the prosthesis. Bioprostheses in young women are associated with an increased risk of structural valve deterioration, which in some reports appear further accelerated in pregnancy. The risk of failure is estimated to be at least 50% in 10 years and higher if in the mitral position. Therefore, most women of childbearing age will need reoperation and the risk of a second open heart surgery should be considered when discussing the risk with the patient. The newer pericardial bioprostheses may offer better durability, but not enough data are available at the moment to make an estimate of the risk. Homografts appear to have a very low risk of failure even in younger patients and also offer superior hemodynamic profiles over other valves and should therefore be considered when possible.

Mechanical valves are indicated in pregnant patients with other coexisting heart disorders requiring anticoagulation, eg, atrial fibrillation, apical thrombus, or history of thromboembolism. Maternal thromboembolism complicates 4–14% of pregnancies in women with mechanical valves despite a therapeutic international normalized ratio (INR). This complication is more likely in patients with the older generation valves (caged-ball, tilting disk) in the mitral position but is also reported in the newer bileaflet valves. The choice of prosthetic valve and the safe method of anticoagulation are therefore still of concern in pregnant patients and need further study.

Unfortunately, significant maternal and fetal risk of either hemorrhage or thrombosis with the accompanying use of warfarin or heparin remains a major problem. The decision on the choice of anticoagulation should therefore be made with both the patient and the physician after full discussion of potential risks and benefits, and the risk of pregnancy in patients with prosthetic heart valves should be discussed in detail with the patient and the family prior to conception.

The incidence of warfarin embryopathy has been estimated to be 4–10% and occurs after the embryo has been exposed to warfarin during the first trimester. Heparin, which does not cross the placenta, was believed to be safe for use during pregnancy; however, studies have reported the risk of thromboembolism, including fatal valve failure, may be as high as 12–24% in high-risk patients receiving either subcutaneous unfractionated heparin or low-molecular-weight heparin (LMWH). More recently, an 8.6% risk of valve thrombosis in pregnant patients treated with a subcutaneous LMWH was demonstrated. Many of these cases may be attributed to either inadequate dose, lack of monitoring, or subtherapeutic anti-Xa levels. In studies where anti-Xa levels were monitored, the risk of thromboembolism was very low (2%). High-risk cases may benefit from addition of low-dose aspirin. Table 31–3 shows a recommended regimen for anticoagulation in mechanical prosthetic heart valves taking into account the risk of the patient as well as the risk of side effects from the drugs.

Table 31–3. Recommended Approach for Anticoagulation Prophylaxis in Women with Prosthetic Heart Valves during Pregnancy.

  Higher Risk Lower Risk
Conditions   First-generation prosthetic heart valve (eg, Starr-Edwards, Bjork Shiley) in the mitral position. Second-generation prosthetic heart valve (eg, St. Jude Medical, Medtronic-Hall) in mitral position.
Atrial fibrillation. Any mechanical prosthetic heart valve in the aortic position.
History of thromboembolism while receiving anticoagulation therapy.
Treatment   Warfarin (INR 2.5–3.5) to 35th week, then UFH (mid-interval aPTT > 2.5) or LMWH (pre-dose anti-Xa ~0.7) + ASA 80–100 mg per day. Subcutaneous UFH (mid-interval aPTT 2.0–3.0) or LMWH (pre-dose anti-Xa ~0.6) for 12 weeks, followed by warfarin (INR 2.5–3.0) to 35th week, then subcutaneous UFH (mid-interval aPTT 2.0–3.0) or LMWH (pre-dose anti-Xa ~0.6).
OR OR
UFH (aPTT 2.5–3.5) or LMWH (pre-dose anti-Xa ~0.7) for 12 weeks, followed by warfarin (INR 2.5–3.5) to 35th week, then UFH (aPTT > 2.5) or LMWH (pre-dose anti-Xa ~0.7) + aspirin 80–100 mg/day. Subcutaneous UFH (mid-interval aPTT 2.0–3.0) or LMWH (pre-dose anti-Xa ~0.6) throughout pregnancy.

aPTT, activated partial prothrombin time; INR, international normalized ratio; LMWH, low-molecular-weight heparin; UFH, unfractionated heparin.

Modified, with permission, from Elkayam U. JACC. 2005;46:403–10.

Infective Endocarditis

Underlying structural abnormalities of the heart predispose patients to the development of infective endocarditis. The most common cause is rheumatic heart disease, with others being mitral valve prolapse, injecting drug abuse, and iatrogenic procedures. The estimated incidence of infective endocarditis during pregnancy is 0.005–1.0% of all pregnancies. Although it is rare, the development of infective endocarditis during pregnancy can have devastating consequences, with maternal and fetal mortality rates estimated to be 22% and 15%, respectively. The clinical diagnosis and the management of infective endocarditis in pregnancy is the same as for nonpregnant patients (see Chapter 29); however, special consideration must be given to the diagnostic and therapeutic approaches during pregnancy to reduce the risk to the fetus.

Rheumatic Heart Disease

Despite an overall decline in the incidence of rheumatic heart disease in Europe and North America, rheumatic valvular disease remains common in women of childbearing age.

The cardiac involvement in acute rheumatic fever is a pancarditis involving the endocardium, myocardium, and pericardium. It is the involvement of the endocardium, including the valvular and the subvalvular apparatus that gives rise to the acute manifestations as well as causes the development of chronic rheumatic valvular heart disease. The specific valvular conditions are described in previous sections. The mitral valve is most commonly affected, followed by the aortic valve, and less frequently the tricuspid and pulmonic valves.

Mild rheumatic fever may be difficult to diagnose in pregnancy due to tachycardia, functional murmur, and anemia. The management of acute rheumatic fever is similar in pregnant and nonpregnant patients and consists of bed rest, anemia correction, and penicillin. In severe cases, vasodilators, positive inotropes, or even surgery may be required. Echocardiography can be performed safely during pregnancy to delineate myocardial and heart valve function.

American College of Cardiology/American Heart Association Task Force on Practice Guidelines; Society of Cardiovascular Anesthesiologists; Society for Cardiovascular Angiography and Interventions; Society of Thoracic Surgeons, Bonow RO et al. ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing committee to revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): developed in collaboration with the Society of Cardiovascular Anesthesiologists: endorsed by the Society for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons. Circulation. 2006 Aug 1;114(5):e84–231. [PMID: 16880336]

Campuzano K et al. Bacterial endocarditis complicating pregnancy: case report and systematic review of the literature. Arch Gynecol Obstet. 2003 Oct;268(4):251–5. [PMID: 12728325]

Elkayam U et al. Valvular heart disease and pregnancy: part I: native valves. J Am Coll Cardiol. 2005 Jul 19;46(2):223–30. [PMID: 16022946]

Elkayam U et al. Valvular heart disease and pregnancy: part II: prosthetic valves. J Am Coll Cardiol. 2005 Aug 2;46(3):403–10. [PMID: 16053950]

Reimhold SC et al. Clinical practice. Valvular heart disease in pregnancy. N Engl J Med. 2003 Jul 3;349(1):52–9. [PMID: 12840093]

Stout KK et al. Pregnancy in women with valvular heart disease. Heart. 2007 May 5;93(5):552–8. [PMID: 16905631]

Myocarditis

This inflammatory process is either focal or diffuse and involves the heart musculature. Of all the infectious and noninfectious causes, viral infection with coxsackie B virus is the most common, accounting for nearly 50% of cases. Acute rheumatic fever is discussed in the previous section. Other important causes include AIDS and Chagas disease due to Trypanosoma cruzi, which is the most common cause in South and Central America. Only a few cases of myocarditis have been reported in pregnancy. Clinical manifestations range from incidental finding of silent myocarditis to overt heart failure with hemodynamic collapse. In the acute stage, the electrocardiogram (ECG) is almost always abnormal, showing Q waves with ST and T wave changes, which may mimic acute MI. The erythrocyte sedimentation rate (ESR) and cardiac enzymes are usually elevated. Viral cultures may or may not be helpful. Noninvasive imaging studies may reveal regional wall motion abnormalities. Although endomyocardial biopsy is the gold standard for the diagnosis of myocarditis, a negative result does not rule it out and rarely does the biopsy aid in diagnosing the etiology or guide management. Therefore, endomyocardial biopsy is not routinely recommended. All pregnant women in whom myocarditis is suspected should be hospitalized. Therapy is supportive, with bed rest; avoidance of strenuous activity; and treatment of heart failure with digoxin, diuretics, and vasodilators. Angiotensin-converting enzyme (ACE) inhibitors should be avoided because of the risk of fetal anomalies. Administration of corticosteroids and immunosuppressive therapy has been controversial and has demonstrated no proven benefit. Potential complications of myocarditis include arrhythmia, heart blocks, and cardiogenic shock. Anticoagulation should be seriously considered, especially for patients with severe left ventricular dysfunction.

Cardiomyopathy

Peripartum Cardiomyopathy

This rare but distinct form of heart failure with left ventricular dysfunction occurs during pregnancy or postpartum. Classically, it is described as occuring between the last month of pregnancy and 5 months postpartum, but cases that do not appear different have been reported from week 17 of pregnancy to 6 months postpartum. Peripartum cardiomyopathy remains a diagnosis of exclusion. The prevalence appears to be increasing, but this is most likely due to increased diagnosis with the common use of echocardiography. Its estimated incidence in the United States is 1 in 4000 and may be higher in other countries. Its cause is unknown but is probably multifactorial. Histopathology reveals a dilated heart with pale myocardium, but myocardial biopsy is of little value. Because signs and symptoms of normal pregnancy resemble heart failure, peripartum cardiomyopathy is easily missed or diagnosed late in the course. Peripartum cardiomyopathy usually presents with dyspnea, cough, orthopnea, paroxysmal nocturnal dyspnea, fatigue, palpitations, and chest pain. Echocardiography is central to diagnosis. The echocardiogram demonstrates dilated left ventricle with marked overall impairment of systolic function. Pulmonary artery catheter placement should be considered for optimized treatment of these patients. Medical therapy is essentially supportive and similar to that for other forms of heart failure and includes salt restriction, diuretics, digoxin, and afterload reduction with hydralazine (the drug of choice). Angiotensin-converting enzyme inhibitors are contraindicated during pregnancy because of associated fetal central nervous system anomalies but can be used after delivery. Heparin should seriously be considered for treating possible thromboembolic phenomena in pregnant patients with very low left ventricular ejection fraction (< 35%). In cases refractory to medical therapy, use of an intra-aortic balloon pump for temporary stabilization and left ventricular assist device as a bridge to transplant are indicated. Most patients recover partially or even completely. However, mortality rates of 10–56% have been reported. Nevertheless, women with a history of peripartum cardiomyopathy have a significant risk of deleterious fetal and maternal outcome in subsequent pregnancies, even if their left ventricular function has returned to normal. Patients who have had fulminant courses and whose left ventricular function has remained depressed should be advised against becoming pregnant again. Recovery of left ventricular function may continue beyond 6 months, and repeat echocardiograms are recommended.

Hypertrophic Cardiomyopathy

This primary myocardial disease shows a characteristic hypertrophy of the left or right ventricular myocardium. The hypertrophy is asymmetric and most commonly involves the intraventricular septum (asymmetric septal hypertrophy). Pathophysiologic mechanisms include presence of a hyperdynamic left ventricle, obstruction of left ventricular outflow tract, mitral regurgitation, and myocardial ischemia. Prevalence in the young population (aged 23–35 years) is 2 per 1000. A large number of patients are asymptomatic. Severe illness is manifested by poor functional capacity, heart failure, and sudden death.

Dyspnea is the most common symptom, with others being chest pain (which may be postprandial), dizziness, syncope, and palpitations. In younger patients, sudden death may be the first manifestation, with an annual incidence in the population being 6%. Physical examination varies from normal to characteristic findings in patients with high gradients. The auscultatory hallmark is a diamond-shaped, grade 3–4/6 systolic murmur, heard best at apex radiating to the left sternal border. The murmur increases in intensity during the strain phase of the Valsalva maneuver. Electrocardiogram shows ventricular hypertrophy, ST and T changes, and Q waves in inferolateral leads. Ventricular arrhythmias are commonly seen on Holter monitoring. Echocardiography diagnostically demonstrates asymmetric septal hypertrophy (with a ratio of septum to posterior wall thickening exceeding 1.5) and decreased septal motion.

Most patients do well during pregnancy. High-risk pregnant patients with a higher likelihood of worsening symptoms during pregnancy include those who were symptomatic prior to pregnancy and asymptomatic patients with left ventricular dysfunction. Increased incidence of supraventricular as well as ventricular arrhythmia in pregnancy has been reported. Maternal hypertrophic cardiomyopathy does not influence fetal outcome, although in about half of the patients it is familial with autosomal-dominant inheritance and confers a 50% risk for affection of the child. Genetic counseling is therefore recommended and a detailed discussion regarding risks and a thorough evaluation of the patient is required prior to conception.

In asymptomatic patients, outcome is usually good, but close monitoring is recommended. Therapy needs to be individualized in symptomatic patients. -Blockers have been used most frequently and relatively safely in symptomatic patients but are not recommended for routine use. Of the calcium channel blockers, verapamil has been used sporadically in pregnant patients. Dual-chamber pacing for arrhythmia has been shown beneficial but is reserved for severely symptomatic cases refractory to medical therapy. Surgical myectomy has not yet been reported in pregnancy. Atrial fibrillation occurs in 10% of the patients, leading to an increased risk of systemic emboli and hemodynamic worsening. Sotalol, procainamide, and DC cardioversion have all been used to treat pregnant patients. Prophylactic placement of an implantable cardioverter-defibrillator should be considered in patients with high-risk features similar to nonpregnant patients. Alcohol septal ablation may reduce symptoms but does not alter prognosis. Hemodynamic monitoring with a pulmonary catheter is recommended for clinical deterioration encountered during labor and delivery and should be considered even in asymptomatic patients. Fortunately, the strain of vaginal delivery is well tolerated in women with hypertrophic cardiomyopathy. Cesarean section is reserved for obstetric indications. Epidural anesthesia should be avoided. Magnesium should be used for tocolysis if needed.

Autore C et al. Risk associated with pregnancy in hypertrophic cardiomyopathy. J Am Coll Cardiol. 2002 Nov 20;40(10):1864–9. [PMID: 12446072]

Elkayam U et al. Maternal and fetal outcomes of subsequent pregnancies in women with peripartum cardiomyopathy. N Engl J Med. 2001 May 24;344(21):1567–71. [PMID: 11372007]

Pearson GD et al. Peripartum cardiomyopathy: National Heart, Lung, and Blood Institute and Office of Rare Diseases (National Institutes of Health) workshop recommendations and review. JAMA. 2000 Mar 1;283(9):1183–8. [PMID: 10703781]

Sliwa K et al. Peripartum cardiomyopathy. Lancet. 2006 Aug 19;368(9536):687–93. [PMID: 16920474]

Coronary Artery Disease

Coronary artery disease is a leading cause of death in women in the United States. Coronary artery disease kills more women than the next 16 leading causes of death combined. The incidence of MI during pregnancy and postpartum is estimated to be 3–7 in 100,000 and predominantly antepartum or intrapartum. Because of a trend toward older childbearing age, the incidence of coronary artery disease may be increasing. Earlier studies reported a mortality rate of 37–50% due to MI during pregnancy. However, recent data suggest the rate is much lower at 5–8%, possibly due to improved diagnosis and treatment. The risk of MI in pregnancy is increased threefold to fourfold in comparison with the nonpregnant state. Risk factors include age (30-fold increased if older than 40 years compared with younger than 20 years), hypertension, diabetes mellitus, smoking, and thrombophilia (Table 31–4). The causes of MI in pregnancy include atherosclerosis, congenital lesions (anomalous origin of coronary artery), inflammatory diseases of coronary arteries (Kawasaki disease), connective tissue or vasospastic disorders, and spontaneous coronary artery dissection, which may account for up to 20% of cases. Up to 30% of the women who undergo coronary angiography will have normal or nonobstructive coronary arteries indicating that vasospasm and spontaneous lysis of thrombus play a role in the process.

Table 31–4. Risk Factors for Pregnancy-Related Acute Myocardial Infarction.

Risk Factor Univariate Risk Odds Ratio P Value  Multivariate Risk Odds Ratio P Value 
Age, years  
< 20 (Ref) 1   1  
20–24 2.4 NS 1.9 NS
25–29 4.3 0.02 3.3 NS
30–34 9.5 < 0.01 6.7 < 0.01
35–39 20.5 < 0.01 16.0 < 0.01
40 31.6 < 0.01 15.2 < 0.01
Race  
White (Ref) 1   1  
Black 1.4 NS 1.4 NS
Hispanic 0.5 0.02 0.8 NS
Condition  
Hypertension 11.7 < 0.01 21.7 < 0.01
Diabetes 3.2 < 0.01 3.6 < 0.01
Smoking 6.2 < 0.01 8.4 < 0.01
Anemia 2.0 < 0.01 1.6 NS
Thrombophilia 22.3 < 0.01 25.6 < 0.01
Preeclampsia 1.6 0.03 0.1 < 0.01
Postpartum bleeding 2.1 0.02 1.8 NS
Transfusion 7.4 < 0.01 5.1 < 0.01
Postpartum infection 2.5 0.04 3.2 0.02

Modified, with permission, from James AH. Circulation. 2006;113:1564–1571.

Most MIs that occur during pregnancy are anterior and transmural, involving the left anterior descending artery. Successful treatment of acute MI during pregnancy with thrombolytic therapy has been reported, but given the risk of placental and fetal bleeding, percutaneous coronary intervention is the preferred treatment for acute ST-elevation MI in pregnancy. -Blockers are the mainstay of medical therapy. Efforts should be made to limit myocardial oxygen consumption, particularly during late pregnancy and delivery, in women with known coronary artery disease.

The most common presentation is angina pectoris. Patients with high index of suspicion should undergo a stress test for risk stratification. Left ventricular function needs to be assessed to determine the choice of therapy and predict likelihood of survival. The normal physiologic changes of pregnancy may precipitate myocardial ischemia and heart failure in women with left ventricular impairment caused by an infarct. Troponin I remains the most useful marker for monitoring pregnant women for a myocardial injury because it is undetectable during normal labor and delivery. Lipid-lowering drugs of the statin-type are contraindicated during pregnancy due to reported teratogenicity, and the risk clearly outweighs the potential benefit.

Ladner HE et al. Acute myocardial infarction in pregnancy and the puerperium: a population-based study. Obstet Gynecol. 2005 Mar;105(3):480–4. [PMID: 15738011]

James AH et al. Acute myocardial infarction in pregnancy: a United States population-based study. Circulation. 2006 Mar 28;113(12):1564–71. [PMID: 16534011]

Arrhythmias

Most arrhythmias occurring during pregnancy are benign. Sinus tachycardia, sinus arrhythmia, sinus bradycardia, atrial premature beats, and ventricular premature beats are relatively common during pregnancy. These arrhythmias are hemodynamically insignificant and require no treatment, and the patient can be reassured of their innocence. The occurrence of more complex arrhythmias should, however, raise the suspicion of underlying cardiac disease. Symptomatic arrhythmias, which are rare during pregnancy, may develop during an otherwise uncomplicated pregnancy or in association with underlying cardiac disease. In fact, cardiac arrhythmias may be the first manifestation of cardiac disease during pregnancy.

Supraventricular Arrhythmias

Paroxysmal Supraventricular Tachycardia

The most common arrhythmia encountered during pregnancy is paroxysmal supraventricular tachycardia (PSVT); it has been estimated to occur in approximately 3% of pregnant patients. In patients with a previous history of PSVT, the frequency and severity of the episodes may increase during pregnancy. The symptoms of PSVT are dyspnea, lightheadedness, and anxiety in patients without underlying cardiac disease. In patients with underlying cardiac abnormalities, angina, heart failure, and syncope may occur as a result of myocardial ischemia and decreased cardiac output. Although there is concern about the effects of hypotension on the fetus during these episodes, women with PSVT do not have an increase in perinatal complications.

Atrial Flutter and Atrial Fibrillation

Atrial flutter, which is uncommon during pregnancy, and atrial fibrillation are usually found in patients with underlying cardiac disease. The hemodynamic consequences and the associated symptoms depend on the underlying cardiac status. During pregnancy, atrial fibrillation is most commonly found in association with mitral stenosis. The development of this arrhythmia in these patients may precipitate congestive heart failure and embolic events. Consideration should be given to anticoagulation therapy if persistent. -Blockers and digoxin are preferred for rate control.

Atrioventricular Nodal Reentrant Tachycardia

This arrhythmia may present the first time during pregnancy. Structural heart disease needs to be excluded with an echocardiogram. Adenosine can be safely given and usually terminates the arrhythmia. In recurrent cases, a -blocker can be given, but drugs should be avoided if possible. The patients should be instructed in the Valsalva maneuver, which may terminate the tachycardia.

Wolff-Parkinson-White Syndrome

This preexcitation syndrome usually occurs in patients without underlying cardiac disease. Patients with Wolff-Parkinson-White (WPW) syndrome may have recurrent arrhythmias—most commonly, atrioventricular (AV) reentry tachycardia, atrial fibrillation, or atrial flutter. The hemodynamic effects of the associated arrhythmias are related to the type of arrhythmia and the ventricular rate. Many patients with WPW syndrome are asymptomatic, but pregnancy is associated with an increased incidence of arrhythmias in women with this syndrome.

Ventricular Arrhythmias

Premature Ventricular Complexes

Premature ventricular complexes (PVCs) are relatively common in pregnant women and are associated with complaints of palpitations. Pregnant women with PVCs and no underlying cardiac disease have an excellent prognosis and require no treatment. Reassurance to the patient is frequently all that is required, along with avoidance of such aggravating factors as smoking and stimulants.

Ventricular Tachycardia

Defined as the occurrence of three or more consecutive ventricular complexes, ventricular tachycardia is a serious cardiac arrhythmia that, if sustained, can lead to death. Ventricular tachycardia is rare during pregnancy, but when it occurs, it is usually associated with underlying cardiac disease. The most common cardiac abnormalities associated with ventricular tachycardia are mitral valve prolapse, valvular disease, and cardiomyopathy. The prognosis for patients with nonsustained ventricular tachycardia (less than 30 seconds in duration) and no underlying cardiac disease is excellent. In such patients, the ventricular tachycardia is catecholamine-sensitive, and extreme exercise should be avoided. In some patients, therapy with -adrenergic blocking drugs may be indicated. Sustained ventricular tachycardia (more than 30 seconds in duration) or hemodynamically significant ventricular tachycardia is usually associated with underlying cardiac disease, and therapy with antiarrhythmics is usually indicated. Such patients should also undergo evaluation for such precipitating factors as myocardial ischemia, electrolyte imbalance, congestive heart failure, digitalis intoxication, stimulants, and hypoxia. Drugs that can be used are procainamide, lidocaine, or sotalol. Amiodarone should be avoided. In hemodynamically unstable patients, immediate DC cardioversion should be performed. Patients with aborted sudden death, syncopal ventricular tachycardia, ventricular fibrillation or flutter should have an implantable cardioverter-defibrillator implanted, preferably under echocardiographic guidance.

Heart Blocks

First-degree heart block is evident as PR prolongation on the ECG and results from an increased time of conduction through the AV junction. First-degree heart block is primarily associated with rheumatic heart disease or digitalis therapy and does not usually require therapy. Second-degree heart block can may be divided into two types: Mobitz type I (Wenckebach) and Mobitz type II. Mobitz type I is characterized by progressive lengthening of the PR interval until an impulse is blocked. It is a relatively benign disorder and occurs when vagal tone is increased. Treatment is seldom indicated. Mobitz type II is a sudden block of conduction without previous prolongation of the PR interval. It often precedes the development of complete heart block. It is rare during pregnancy but may occur in association with rheumatic heart disease or infections. If the ventricular rate is slow and the patient is symptomatic, treatment with permanent pacing is indicated.

Complete heart block can be congenital or acquired. Its onset is usually prior to the pregnancy, and it rarely progresses. Approximately half the cases of complete heart block occurring during pregnancy have an associated ventricular septal defect. Other causes include ischemic heart disease, myocarditis, and rheumatic heart disease. The need for pacemaker therapy depends on the ventricular escape rate. Symptoms are rare at a rate of 50–60 beats/min; if the rate suddenly slows, however, syncope may develop. Permanent pacing is indicated in such patients.

Trappe HJ. Acute therapy of maternal and fetal arrhythmias during pregnancy. J Intensive Care Med. 2006 Sep–Oct;21(5):305–15. [PMID: 16946446]

Pericardial Diseases

Pericarditis is usually a mild, self-limited disease. Its incidence, diagnosis, and treatment are similar in pregnant and nonpregnant patients. Most pregnancies, even the complicated ones, may safely reach full term. Idiopathic pericarditis is the most common cause of pericardial disease, others being trauma, infections (viral, bacterial, fungal, tuberculosis), radiation, and collagen vascular diseases.

Sharp, stabbing chest pain that is exacerbated in the supine position and relieved by leaning forward is the most common complaint. Pathognomonic finding of pericardial friction rub is best heard with the diaphragm of the stethoscope over the second and fourth intercostal spaces in midclavicular line or the left sternal border, with the patient leaning forward and inspiring deeply. Characteristic ST-segment elevations with upward concavity and upright T waves have been reported in 80% of patients with acute pericarditis. Echocardiography is an important diagnostic modality and may reveal thickened pericardium, pericardial effusion and, most importantly, cardiac tamponade.

Pregnant patients in whom pericarditis is suspected should be hospitalized for complete bed rest. Nonsteroidal antiinflammatory drugs (NSAIDs), aspirin, and indomethacin are effective analgesics. Corticosteroids should be avoided in tuberculosis. Pericardiectomy is reserved for severe, relapsing pericarditis, refractory to medical treatment. Symptoms of a complicating pericardial effusion with cardiac tamponade mimics the symptoms of pregnancy and includes shortness of breath, dyspnea on exertion, and fatigue. Echocardiogram will quickly establish the diagnosis. Treatment for symptomatic cardiac tamponade is percutanous drainage with surgical pericardial window reserved for refractory cases.

Asymptomatic pericardial effusion is frequently encountered in all trimesters, most commonly in the third, but resolves postpartum. Pericardial constriction has been rarely reported in pregnancy, although it could occur as a pericarditis sequel. Most patients have dyspnea, marked edema, and ascites in the latter half of pregnancy. Diuretics, corticosteroids, and pericardiectomy (reserved for refractory cases, and associated with reasonable maternal and fetal risk) have all been used to treat pericardial constriction in pregnant patients. Preterm delivery and fetal death have been reported.

Pulmonary Hypertension

Primary Pulmonary Hypertension

This uncommon although distinct entity is defined as mean pulmonary artery pressure by right heart catheter of more than 30 mm Hg at rest, or more than 40 mm Hg during exercise, without a demonstrable cause. Primary pulmonary hypertension poses a significant risk to pregnant women, with mortality approaching 40%, warranting prevention of pregnancy or early therapeutic abortion. The most common presenting symptoms are dyspnea, fatigue, chest pain, palpitations, syncope or near syncope, and Raynaud phenomenon. Characteristic physical findings are a result of markedly increased pulmonary pressures, leading to right ventricular hypertrophy and failure with decreased cardiac output. The echocardiogram reveals elevated pulmonary artery pressures, right atrial enlargement, right ventricular hypertrophy, and tricuspid regurgitation. A new onset or worsening of symptoms is commonly seen in the second and third trimesters.

Treatment with prostacyclin infusion for short periods to lower pulmonary artery pressure in pregnancy has been reported to be safe and effective. Incidents of premature labor and delivery are high. Patients should lie in the left lateral decubitus position to improve cardiac output. Planned vaginal delivery seems to be safe in stable patients. Epidural anesthesia has been used in most reported cases. Patients should be monitored for 7–10 days postpartum prior to discharge to ensure stability. Due to its grave prognosis and a high incidence of maternal and fetal morbidity and mortality, pregnancy is contraindicated in patients with primary pulmonary hypertension (see Table 31–2). Therapeutic abortion is indicated as soon as possible if pregnancy occurs. Adequate counseling should be provided to all patients regarding sterilization.

Stewart R et al. Pregnancy and primary pulmonary hypertension: successful outcome with epoprostenol therapy. Chest. 2001 Mar;119(3):973–5. [PMID: 11243988]

Thromboembolic Disease

Venous thromboembolic disease is a leading cause of morbidity and mortality during pregnancy and postpartum. Venous thromboembolism affects pregnant women five times more frequently than nonpregnant women. It is estimated to complicate 2 in 1000 pregnancies. The diagnosis is complicated by symptoms similar to usual pregnancy symptoms such as shortness of breath, tachycardia, and leg swelling. As many as up to 33% of deep venous thrombosis may occur in the first trimester, although the risk is highest postpartum (five times higher than during the pregnancy). The immediate postpartum period risk for pulmonary embolism is 15 times greater than during the pregnancy. Risk factors for venous thromboembolism includes age > 35 years, weight > 165 lbs, a family or personal history of deep venous thrombosis or pulmonary embolism, varicose veins, smoking, or any known hypercoagulable state as well as multiple previous pregnancies. Pulmonary embolism will occur in 15–24% of patients with untreated deep venous thrombosis and may be fatal in 15%. Diagnosis of deep venous thrombosis should be made with compression ultrasound or impedance plethysmography. Magnetic resonance imaging (MRI) can be performed to diagnose iliac thrombosis. The diagnosis of pulmonary embolism is complicated by the need to avoid radiation in the pregnant patient. However, ventilation-perfusion scannning is considered safe throughout pregnancy and should be the first step in the diagnosis of a pulmonary embolism. To further decrease radiation, consideration should be given to performing perfusion scan alone. If there is no defect, then pulmonary embolism would be very unlikely. The gold standard for pulmonary embolism is pulmonary angiogram. Except in the first trimester, pulmonary angiogram exposes the fetus to less radiation than a helical CT scan. An echocardiogram may support the diagnosis of acute embolus by demonstrating right heart enlargement without hypertrophy and elevated pulmonary artery pressure. Hypokinesis with relative sparing of the right ventricular apex may be seen. The main treatment for deep venous thrombosis during pregnancy consists of heparin, although warfarin can be given after the first trimester until 35 gestation weeks. If unfractionated heparin is used, a target activated partial prothrombin time level should be 2.0–2.5. If an LMWH is used, the patient should be monitored with anti-Xa levels. Pulmonary embolism, if stable, should be treated with intravenous heparin for at least 5 days. Oral anticoagulation should be continued for 6 months thereafter. In unstable pulmonary embolism, consideration to thrombolysis and embolectomy should be given. An inferior vena caval filter may also be needed.

Heit JA et al. Trends in the incidence of venous thromboembolism during pregnancy or postpartum: a 30-year population-based study. Ann Intern Med. 2005 Nov 15;143(10):697–706. [PMID: 16287790]

Stone SE et al. Pulmonary embolism during and after pregnancy. Crit Care Med. 2005 Oct;33(10 Suppl):S294–300. [PMID: 16215350]

Diseases of the Aorta

Marfan Syndrome

Marfan syndrome is an inheritable autosomal-dominant connective tissue disorder of the fibrillin gene on chromosome 15 with a prevalence of 1 in 3000–5000 individuals. It involves the ocular, skeletal, and cardiovascular systems. Patients are predisposed to aortic dissection or actual rupture of the aorta most commonly originating in the ascending portion during pregnancy, most likely in the third trimester. High-risk patients have significant associated cardiac abnormalities, such as mitral valve prolapse, mitral and aortic regurgitation, and an aortic root greater than 4.0 cm in diameter. All women with Marfan syndrome planning to become pregnant should undergo a screening transthoracic echocardiogram. High-risk patients (aortic root > 4.0 mm or rapidly progressive dilatation) should have elective surgery before conception, preferably with valve-sparing surgery if no significant aortic regurgitation is present. If the diagnosis is made during pregnancy, -blockers are strongly recommended, with some authorities advocating prompt termination of pregnancy with aortic repair. Close follow-up with echocardiography should be performed. Women at increased risk for complications during pregnancy should be advised against attempting a pregnancy that may be associated with a 50% maternal mortality rate (Table 31–2). Patients with no dissection or aortic root enlargement can deliver vaginally with epidural anesthesia and facilitated stage 2 of labor. However, if there is aortic root enlargement, aortic regurgitation, or rapid progression of the aorta size, caesarean delivery is recommended. The risk of the offspring inheriting the disorder is 50%.

Loeys-Dietz Syndrome

This is a recently recognized syndrome caused by genetic mutation in transforming growth factor (TGF)- with autosomal dominant inheritance with variable clinical expression. The most common manifestations are aortic aneurysms with a high risk of dissection, hypertelorism, bifid uvula or cleft palate, generalized arterial tortuosity, and aneurysms throughout the arterial tree. Loeys-Dietz syndrome may be misdiagnosed as Marfan syndrome, but patients with Loeys-Dietz syndrome will have normal fibrillin gene. Women with this syndrome should be advised against pregnancy due to the risk of aortic dissection with normal aortic diameter and a risk for uterine rupture during pregnancy.

Immer FF et al. Aortic dissection in pregnancy: analysis of risk factors and outcome. Ann Thorac Surg. 2003 Jul;76(1):309–14. [PMID: 12842575]

Milewicz DM et al. Treatment of aortic disease in patients with Marfan syndrome. Circulation. 2005 Mar 22;111(11):e150–57. [PMID: 15781745]

Williams JA et al. Early surgical experience with Loeys-Dietz: a new syndrome of aggressive thoracic aortic aneurysm disease. Ann Thorac Surg. 2007 Feb;83(2):S757–63. [PMID: 17257922]

Hypertension

Hypertension affects 12% of pregnancies and is responsible for 18% of maternal deaths in the United States. Hypertension in pregnancy is defined as an increase in systolic blood pressure of 30 mm Hg or more or in diastolic pressure of 15 mm Hg or more. The hypertension may be chronic (> 135/85 mm Hg before pregnancy or before 20 weeks gestation and persistent more than 6 weeks postpartum), transient, or part of preeclampsia or eclampsia (hypertension after 20 gestation weeks with new proteinuria > 300 mg over 24 hours and edema). The drug treatment of choice for mild hypertension is methyldopa. For severe hypertension drugs such as hydralazine, labetalol, and nifedipine can be used. Target diastolic blood pressure is just below 100 mm Hg for severe cases and lower to 85 mm Hg for nonemergencies.

Vidaeff AC et al. Acute hypertensive emergencies in pregnancy. Crit Care Med. 2005 Oct;33(10 Suppl):S307–12. [PMID: 16215352]

Clinical Findings

History

The evaluation of heart disease in pregnancy is difficult due to the normal anatomic and physiologic changes of pregnancy. A careful history taking therefore is very important and should include a history of rheumatic fever, valvular disorder, arrhythmia, congenital heart disease, coronary risk factors or established coronary artery disease, and cardiac surgery.

Symptoms and Signs

Reduced exercise tolerance and fatigue are the most common symptoms reported in pregnant women, probably due to increased body weight and anemia. Dizziness, light-headedness, or even syncopal episodes may occur during the latter part of pregnancy because mechanical compression of the uterus on the inferior vena cava decreases venous return, and thus the cardiac output. Palpitations are also a frequent complaint but usually are not associated with a significant arrhythmia. Dyspnea and orthopnea, probably due to hyperventilation, are also reported.

Physical Examination

The physical examination of pregnant patients with normal cardiovascular systems changes because of the increased hemodynamic burden. The evaluation of patients with suspected heart disease during pregnancy requires a thorough knowledge of the normal physiologic changes (see Table 31–1).

A normal pregnant patient has a slightly fast resting heart rate, large pulse, slightly widened pulse pressure, and warm extremities. Jugular venous distention is seen starting at the twentieth week. Edema of the ankles and legs is commonly encountered in late pregnancy. A prominent but unsustained left ventricular impulse may be palpated in late pregnancy and may simulate the volume overload seen in aortic or mitral regurgitation. The auscultatory findings of normal pregnancy begin late in the first trimester and usually disappear 2–4 weeks after delivery. During cardiac auscultation, the first heart sound is loud and exhibits an exaggerated splitting. The second heart sound during late pregnancy is often increased and may exhibit persistent expiratory splitting, especially with the patient in the left lateral position. A third heart sound has been reported to be frequent in late pregnancy. However, because of its association with heart failure, the presence of a third heart sound should lead to further investigation of underlying heart disease, especially in women with symptoms and other signs suggestive of heart disease. A fourth heart sound is rarely heard during a normal pregnancy.

Systolic murmurs are common during pregnancy and result from the increased blood volume and hyperkinetic state. Most frequently they are innocent early systolic murmurs, grade 1–2/6, that are best heard at the lower left sternal border and over the pulmonary area, radiating to the suprasternal notch or to the left of the neck. They usually represent vibrations created by ejection of blood into the pulmonary trunk. A cervical venous hum or mammary souffle heard best in the right supraclavicular area in a supine position is a benign systolic, or a continuous, murmur occurring in late pregnancy (Table 31–5). Diastolic heart murmurs are unusual and usually represent valvular abnormalities.

Table 31–5. Cardiovascular Signs and Symptoms in Normal Pregnancy.

Symptoms  
Fatigue
Orthopnea
Dyspnea
Decreased functional capacity
Dizziness
Syncope
Physical signs  
Jugular venous distention
Displaced left ventricular apical impulse
Right ventricular heave
Palpable pulmonary impulse
Increased intensity of the first heart sound
Persistent splitting of the second heart sound
Systolic ejection murmur at the left lower sternal border or pulmonary area with radiation to the neck
Cervical venous hum, mammary souffle

Diagnostic Difficulties

Although systolic murmurs are common, the finding of a diastolic murmur is rare during a normal pregnancy and should warrant further diagnostic evaluation. Both systolic and diastolic murmurs associated with cardiac disease can increase or decrease in intensity during pregnancy. Innocent flow murmurs and benign vascular murmurs usually decrease in the sitting position. The systolic murmurs of aortic or pulmonic stenosis usually increase in intensity because of the increased cardiac output and blood volume. The diastolic murmur of mitral stenosis is also increased and may even be first detected during pregnancy. The augmented blood volume and the increased heart rate of pregnancy shorten the diastolic filling period and increase the rate of blood flow across the mitral valve. In contrast, murmurs of mitral or aortic regurgitation may soften or even disappear during pregnancy as a result of the decrease in peripheral vascular resistance. The circulatory changes of pregnancy also affect the auscultatory findings in cardiac abnormalities, such as mitral valve prolapse and hypertrophic cardiomyopathy, which are dependent on volume. The increase in left ventricular volume during pregnancy may attenuate or abolish the click and late systolic murmur typical of mitral valve prolapse. The systolic murmur of hypertrophic obstructive cardiomyopathy may also decrease or disappear as the left ventricular volume increases during pregnancy.

Diagnostic Studies

Electrocardiography

The ECG is an important diagnostic technique that can indicate the presence of underlying cardiac abnormalities. Cardiac chamber hypertrophy, myocardial ischemia and infarction, pericarditis, myocarditis, conduction abnormalities, and the presence of atrial and ventricular arrhythmias may be detected by electrocardiography. In patients with suspected cardiac arrhythmias, ambulatory Holter monitoring may be indicated. During normal pregnancy, sinus tachycardia, a shift of the axis to the left or right may be observed, and transient ST abnormalities are common.

Echocardiography

Transthoracic echocardiography is an important diagnostic noninvasive study, which can be performed safely in pregnancy. The intracardiac structures can be evaluated for abnormalities of the great vessels, cardiac chambers, and heart valves. Chamber sizes and ventricular function can also be measured.

During the echocardiographic examination, the normal physiologic changes that occur with pregnancy should be kept in mind. When the patient is evaluated in the left lateral position, an increase in the diastolic dimensions of the right and left ventricles is common because of volume increases that occur with a normal pregnancy. Because of the increase in the left ventricular dimensions, mitral valve prolapse may improve or disappear during pregnancy. Right and left atrial dimensions may also increase slightly; these changes increase as the pregnancy progresses. Small pericardial effusions have been noted in late pregnancy in healthy women.

Doppler echocardiography provides reliable quantitative and qualitative information regarding the presence and severity of valvular stenosis and regurgitation. Doppler echocardiography can measure the valve area and gradients across stenotic valves. Small degrees of pulmonary, tricuspid, and mitral regurgitation have frequently been found in normal individuals, whether pregnant or not. In patients with congenital heart disease (corrected or uncorrected) Doppler echocardiography can detect the presence of intracardiac shunts and estimate the shunt ratios by determining the right and left cardiac outputs. It can measure pulmonary artery systolic pressure to assess the effects of the valvular lesions and intracardiac shunts on the pulmonary circulation.

Transesophageal echocardiography (TEE) provides superior images of the intracardiac structures and great vessels, providing the same detailed analysis of cardiac structure, function, and hemodynamic assessment possible with transthoracic echocardiography. Transesophageal echocardiography can be used for patients in whom the transthoracic examination is technically suboptimal and for those with suspected prosthetic or native valve dysfunction, infective endocarditis, congenital heart disease, or aortic dissection. Although experience with TEE during pregnancy has been limited, the procedure should be considered in pregnant patients for whom the risks are less than the possible benefit. The procedure should be performed by an experienced echocardiographer, and fetal monitoring, in addition to the routine monitoring of the patient, should be available (Table 31–6).

Table 31–6. Normal Diagnostic Test Findings in Pregnancy.

Electrocardiogram  
Sinus tachycardia
Increased incidence of arrhythmias
QRS axis deviation
Increased amplitude of R wave in lead V2
 
ST segment and T wave changes
Small Q waves
Echocardiogram  
Mildly increased biatrial size
Increased biventricular dimensions
Mildly increased left ventricular systolic function
Small pericardial effusion
Increased tricuspid valve diameter
Mild tricuspid, pulmonic, and mitral regurgitation
Chest roentgenogram  
Increased lung markings
Horizontal positioning of the heart
Straightened left upper cardiac border

Exercise Tolerance Test

Little is known about the safety of an exercise test to establish ischemic heart disease in pregnancy. Fetal bradycardia, marked hypoxia, acidosis, and severe hypothermia at peak exercise have been reported. In light of these facts, the use of a submaximal stress test (approximately 70% of the maximal predicted heart rate) with close fetal monitoring is recommended, until more information regarding its safety is available. Maximal oxygen consumption, unchanged in pregnancy, could be used for the assessment of the functional status in cardiac patients during pregnancy.

Chest Radiography

The usefulness of chest films during pregnancy is limited because of the potential hazard to the fetus from radiation exposure. Whenever a chest film is believed necessary, the abdominopelvic area should be shielded with lead to minimize exposure. The normal cardiac changes of pregnancy, such as chamber enlargement and the horizontal position of the heart because of the elevation of the diaphragm, should not be misinterpreted as cardiac disease. Newer and more accurate techniques such as Doppler echocardiography have largely replaced chest films in the evaluation of cardiac structure and function.

Radionuclide Studies

Myocardial perfusion scans and radionuclide ventriculography should be avoided, if possible, especially in the first trimester of pregnancy because of the risk of rare but possible fetal malformations. Also, in women of childbearing age, the incidence of coronary heart disease is low and other noninvasive techniques, such as exercise echocardiography, can be used to assess coronary artery disease. In cases of suspected pulmonary embolism, a limited ventilation-perfusion scan (only performing the perfusion phase) may be performed weighing out the risks and the benefits.

Magnetic Resonance Imaging

Magnetic resonance imaging provides multiplanar images of the body with excellent soft-tissue contrast without the use of ionizing radiation. Magnetic resonance imaging is in general regarded safe in pregnancy. However, safety data are limited. Therefore, MRI should be limited to cases where ultrasonography are inconclusive and where patient care depends on further imaging. Gadolinium contrast appears to be safe. However, the safety is not very well proven in the fetus, and therefore, should be reserved for cases where this type of study is important for the health of the mother.

Pulmonary Artery Catheterization

Bedside hemodynamic monitoring can be performed with a balloon-tipped pulmonary artery catheter. In most patients, inflating the balloon permits flotation of the catheter through the right heart without the need for fluoroscopy. With the catheter in the pulmonary artery, the balloon is inflated until it occludes a small vessel; the pulmonary artery wedge pressure obtained reflects the left ventricular end-diastolic pressure. Pulmonary artery pressures and cardiac output can also be measured. The placement of a balloon flotation catheter should be considered during the early stages of labor in any patient with cardiac disease who has been symptomatic during the pregnancy. Furthermore, because of postpartum hemodynamic changes, hemodynamic monitoring should be continued for up to 48 hours following delivery.

Cardiac Catheterization

In some patients with cardiac disease who decompensate during pregnancy, complete diagnostic information cannot be obtained by noninvasive methods alone. This is particularly important when surgical intervention is contemplated. Cardiac catheterization in these patients may need to be performed during pregnancy. Because the radiation required for the performance of this technique has potentially adverse effects on the fetus, cardiac catheterization should be performed only if the needed information cannot be obtained by any other means. Whenever possible, cardiac catheterization should be performed after major organogenesis has occurred (more than 12 weeks after the last menses). The brachial approach is the preferred method to minimize the risk of radiation exposure to the abdomen, which should be lead shielded. The exposure to x-rays should be reduced to a minimum; catheter position can be guided in some cases by Doppler and contrast echocardiography.

Treatment

Pharmacologic Treatment

Treatment of the pregnant patient with cardiac disease requires the collaborative consultation of the obstetrician and cardiologist at regular intervals during gestation and careful planning for delivery with the anesthesiologist. All cardiovascular drugs during pregnancy should be avoided, if possible, especially in the first trimester. Most cardiovascular drugs cross the placenta and are secreted into the breast milk, mandating a detailed evaluation of risk-to-benefit ratio (Table 31–7).

Table 31–7. Alphabetical List of the Commonly Used Cardiovascular Medications, Their Potential Fetal Side Effects, and Overall Safety.

Drugs Potential Side Effects Safety
ACE-I IUGR, prematurity, low birth weight, neonatal renal failure, bony malformations, limb contractures, patent ductus arteriosus, death Contraindicated
Adenosine Limited data (in first trimester only) Safe
Amiodarone IUGR, prematurity, hypothyroidism, prolonged QT in the newborn Unsafe
ARB Same as ACE-I Contraindicated
-Blockers Fetal bradycardia, hypoglycemia and apnea at birth, IUGR, uterine contraction initiation Safe
Calcium channel blocker Maternal hypotension leading to fetal distress, birth defects Verapamil safe
Digoxin Low birth weight Safe
Disopyramide Uterine contraction initiation Safe
Diuretics Hyponatremia, bradycardia, jaundice, low platelets, impaired uterine blood flow Potentially unsafe
Heparin None reported Probably safe
Hydralazine None reported Safe
Lidocaine CNS depression due to fetal acidosis with high blood levels Safe
Mexiletine IUGR, fetal bradycardia, neonatal hypoglycemia, and hypothyroidism Safe
Nitrates Fetal bradycardia Probably safe
Nitroprusside Thiocyanate toxicity Potentially unsafe
Procainamide None reported Safe
Quinidine Premature labor, fetal VIII cranial nerve damage with high blood levels Safe
Sotalol Limited data; bradycardia, reports of death Probably safe
Warfarin Embryopathy, in utero fetal hemorrhage, CNS abnormalities Unsafe

ACE-I, angiotension-converting enzyme inhibitor; ARB, angiotensin receptor blockers; CNS, central nervous system; IUGR, intrauterine growth retardation.

Heart Failure

Treatment of heart failure is more challenging in pregnant patients than in nonpregnant women. Salt restriction and activity limitation are extremely important. In patients with pulmonary congestion, medical therapy should begin with digoxin. Although digoxin has been safely used during pregnancy for many years, blood levels should be monitored to avoid toxicity. Diuretics, although not teratogenic may cause impaired uterine blood flow and placental perfusion, and hence should only be used in severely symptomatic patients. Thiazide diuretics have been associated with neonatal thrombocytopenia, jaundice, hyponatremia, and bradycardia.

Afterload is already reduced during pregnancy, hence further reduction in afterload may only be beneficial in selected cases. Hydralazine, the most frequently used afterload-reducing agent during pregnancy, is a direct arteriolar dilator and has not been associated with adverse fetal effects. Angiotensin-converting enzyme inhibitors are contraindicated in pregnancy due to their associated increased risk of premature delivery, low birth weight, fetal hypotension, renal failure, bony malformations, persistent patent ductus arteriosus, respiratory distress syndrome, and even death. Angiotensin II receptor blockers have similar adverse reactions and are thus rendered unsafe. Data on nitrates are limited and require further evaluation. -Blockers may be used safely.

Arrhythmias

During pregnancy, any precipitating factors of arrhythmia should be avoided or corrected. In general, conservative treatment of cardiac arrhythmias is indicated. DC cardioversion is the treatment of choice in patients with hemodynamic compromise due to arrhythmia. Although no antiarrhythmic is completely safe during pregnancy, most are tolerated well and are relatively safe. Drugs with the longest record of safety should be used as first-line therapy. Digoxin, although one of the safest drugs for treating arrhythmia during gestation, may cause increased risk of prematurity and intrauterine growth retardation. Adenosine has been reported safe and successful in terminating supraventricular tachycardias during pregnancy.

Quinidine, with minimal fetal risk, has the longest record of being used safely and effectively in the treatment of both atrial and ventricular tachycardia during pregnancy. When quinidine is indicated during pregnancy, blood levels should be closely monitored because of drug interactions with warfarin may develop excessively prolonged prothrombin time, with the potential for hemorrhage. Procainamide has also been used safely and is the drug of choice in the treatment of wide-complex tachycardias.

Amiodarone is associated with fetal hypothyroidism, smaller size at birth for date of gestation, and prematurity, and is also secreted in breast milk. Amiodarone is thus reserved only for treating life-threatening arrhythmias or those refractory to other medical therapy. Verapamil, although used during pregnancy, should be discontinued at the onset of labor to avoid dysfunctional labor and postpartum hemorrhage.

-Adrenergic blocking agents are relatively safe and have frequently been used in pregnant patients to treat arrhythmia, hypertrophic cardiomyopathy, and hyperthyroidism. Propranolol is a nonselective -blocker that has been used frequently during pregnancy. Fetal and newborn heart rate, blood glucose levels, and respiratory status should be monitored closely.

Lidocaine may be used for ventricular tachycardia, especially in the setting of an acute MI, but it requires close monitoring of blood levels.

Thrombosis and Thromboembolism

Even though increased concentrations of clotting factors and platelet adhesiveness, and decreased fibrinolysis in pregnancy result in an overall increased risk of thrombosis and embolism, the actual incidence of venous thromboembolism during pregnancy is lower than previously reported. The gestational age at presentation appears to be equally distributed. Pulmonary embolism cases are reported to occur most commonly in the postpartum period and are strongly associated with a cesarean section. About 40% of asymptomatic patients with deep venous thrombosis may indeed have a pulmonary embolism.

The major indications for anticoagulants during pregnancy include the presence of mechanical heart valves and prophylaxis for recurrent pulmonary thromboembolism. Some patients with rheumatic heart disease with atrial fibrillation and cardiomyopathies may also be candidates for anticoagulation during pregnancy. The best method of anticoagulation in a pregnant patient is still controversial. A recommended regimen is suggested in Table 31–3.

Warfarin has been associated with fetal wastage due to spontaneous abortion and stillbirths, optic nerve atrophy and blindness, microcephaly, mental retardation, and even death due to intracranial hemorrhage. Its use in the first trimester is associated with warfarin embryopathy in 4–10% of newborns, a syndrome comprising nasal bone hypoplasia and epiphyseal stippling. Warfarin poses significant risks to both the mother and the fetus during labor and delivery; however, breast-feeding women can be prescribed warfarin because it is not secreted in the breast milk. In the second trimester, warfarin is the treatment of choice, with INR monitoring. Therefore, warfarin should be given only after the 12th gestational week and should be stopped before delivery around 35th week.

Heparin is generally the drug of choice for anticoagulation in pregnant patients, unless there is a very high risk for thromboembolism (see section on Prosthetic Heart Valves). As soon as pregnancy is diagnosed, oral anticoagulants should be discontinued and subcutaneous heparin, with a goal partial thromboplastin time (PTT) of 2–2.5 times normal, should be initiated. If LMWH is used, anti-Xa levels should be monitored. Complications of heparin administration include abdominal wall hematoma or abscess, thrombocytopenia, alopecia, and osteoporosis. At the 36th week of gestation, subcutaneous heparin should be switched to intravenous route. To avoid the risk of bleeding during labor and delivery, heparin should be discontinued 24 hours prior. Anticoagulation should then be resumed 4 hours after delivery.

Low-dose aspirin has been safely used in pregnancy. Dipyridamole should not be used in a pregnant patient. Thrombolytic therapy has been used safely and effectively but should be avoided whenever possible.

Endocarditis Prophylaxis

The American Heart Association does not recommend prophylaxis for infective endocarditis in pregnant patients expected to have an uncomplicated course of pregnancy and labor and delivery. However, because of the unpredictability of labor and delivery, many clinicians opt to treat. Women undergoing urinary catheter placement in established urinary tract infection, and vaginal delivery in vaginal infection should receive intramuscular or intravenous antibiotics. The conservative approach is to administer endocarditis prophylaxis in pregnant patients with mechanical prosthetic heart valves, a history of infective endocarditis, those with most congenital heart disorders, obstructive hypertrophic cardiomyopathy, and those with mitral valve prolapse with mitral regurgitation who are undergoing interventions likely to cause septicemia.

Joglar JA et al. Antiarrhythmic drugs in pregnancy. Curr Opin Cardiol. 2001 Jan;16(1):40–5. [PMID: 11124717]

Surgical Treatment

Ideally, most cardiac diseases requiring surgical correction are diagnosed and treated before the patient becomes pregnant, so the data are anecdotal. In general, cardiac surgery in pregnant patients is not associated with significant maternal risk but may cause fetal wastage. Fetal risk has been reported to be as high as 33%. Pregnant women requiring cardiac surgery need utmost care, adequate valve selection, and anticoagulation to ensure a good outcome.

Surgery should be reserved for severely symptomatic patients and those who are refractory to medical therapy, and it should be avoided in the first trimester, if possible. Procedures not involving cardiopulmonary bypass are preferred because of associated risks of fetal bradycardia and hypoperfusion.

Labor and Delivery

Labor and delivery are periods of maximal hemodynamic stress during pregnancy. Pain, anxiety, and uterine contractions all contribute to altered hemodynamics. Oxygen consumption is higher, and cardiac output is increased up to 50%. Both systolic and diastolic pressures are increased significantly during uterine contractions, especially in the second stage. Anesthesia and analgesia during labor and delivery may affect oxygen consumption, but they do not reduce increased cardiac output secondary to uterine contractions.

Acute decompensation may develop in patients with preexisting cardiac disease. This increase in preload and cardiac output can be devastating in a patient with limited cardiac reserve or an obstructive valvular lesion. Patients at greatest risk for complications during labor and delivery include those with significant pulmonary hypertension and those in NYHA functional class III or IV.

The preferred method of delivery is vaginal, with careful attention paid to pain control by regional anesthesia to avoid tachycardia. Postpartum hemorrhage and excessive fluid intake should be prevented. Invasive hemodynamic monitoring may be needed in some cases to guide treatment rapidly during labor and delivery. In these patients, the monitoring should be continued for at least 24–48 hours after delivery or until hemodynamic stability is ensured. Cesarean section, with few exceptions, should be performed only for obstetric indications because it can also create blood loss and fluid shifts. Regardless of the delivery method, however, effective pain control is absolutely essential. Antibiotic prophylaxis should be administered when indicated.

Prognosis

Maternal mortality and morbidity rates during pregnancy depend on the underlying cardiac lesion and the functional status of the patient (see Table 31–2). The greatest risk of maternal mortality (25–50%) is for patients with pulmonary hypertension, Eisenmenger syndrome, NYHA class III and IV, and Marfan syndrome with a dilated aorta. Pulmonary vascular disease prevents the adaptive mechanisms of normal pregnancy and makes labor, delivery, and the early postpartum period particularly problematic. Moderate-to-severe mitral stenosis, aortic stenosis, the presence of mechanical prosthetic valves, uncomplicated coarctation of the aorta, uncorrected congenital heart diseases (without Eisenmenger syndrome), and Marfan syndrome with a normal aorta are associated with a 5–10% mortality rate. Left-to-right shunts, pulmonary valve disease, corrected congenital heart disease, bioprosthetic valves, and mild-to-moderate mitral stenosis have a mortality rate of less than 1%.

The functional status of a patient should be classified according to the NYHA classification system. Patients in class I or II can be expected to undergo pregnancy with a less than 0.5% risk of death.

Mauri L et al. Valvular heart disease in the pregnant patient. Curr Treat Options Cardiovasc Med. 2001 Feb;3(1):7–14. [PMID: 11139785]

Sadler L et al. Pregnancy outcomes and cardiac complications in women with mechanical bioprosthetic, and homograft valves. BJOG. 2000 Feb;107(2):245–53. [PMID: 10688509]

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