Williams Manual of Pregnancy Complications, 23 ed.

CHAPTER 48. Heart Disease in Pregnancy

Heart disease is the leading cause of death in women who are 25 to 44 years of age. Because it is relatively common in women of childbearing age, heart disease of varying severity complicates about 1 percent of pregnancies. Although maternal mortality related to cardiovascular disease has decreased remarkably over the past 50 years, heart disease still contributes significantly to maternal mortality. Between 1991 and 1999, for example, cardiomyopathy alone was responsible for 8 percent of the 4200 pregnancy-related maternal deaths in the United States.

PHYSIOLOGICAL CONSIDERATIONS

The marked hemodynamic changes stimulated by pregnancy have a profound effect on underlying heart disease in pregnant women. The most important consideration is that during pregnancy cardiac output is increased by as much as 50 percent. Almost half of the total increase occurs by 8 weeks, and it is maximized by midpregnancy. The early increase in cardiac output results from an augmented stroke volume associated with decreased vascular resistance and corresponding diminished blood pressure. Later in pregnancy, there is also an increased resting pulse, and stroke volume increases even more, presumably related to increased diastolic filling from augmented blood volume.

Because significant hemodynamic alterations are apparent early in pregnancy, women with severe cardiac dysfunction may experience worsening of heart failure before midpregnancy. In other women, heart failure develops in the third trimester when the normal hypervolemia of pregnancy becomes maximal. In the majority, however, heart failure develops peripartum when there are additional hemodynamic burdens. This is the time when the physiological capability for rapid changes in cardiac output is frequently overwhelmed in the presence of structural cardiac disease.

DIAGNOSIS OF HEART DISEASE

As shown in Figure 48-1, many of the physiological changes of normal pregnancy tend to make the diagnosis of heart disease more difficult. For example, systolic heart murmurs, accentuated respiratory effort, and edema may occur during normal pregnancy as well as in association with cardiac disease. Listed in Table 48-1 are symptoms and clinical findings that may be suggestive of heart disease during pregnancy. Pregnant women who have none of these findings rarely have serious heart disease.

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FIGURE 48-1 Normal cardiac examination findings in the pregnant woman. S1, first sound; M1, mitral first sound; S2, second sound; P2, pulmonary second sound. (Reproduced, with permission, from Cunningham FG, Leveno KJ, Bloom SL, et al (eds). Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010.)

TABLE 48-1. Clinical Indicators of Heart Disease during Pregnancy

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Diagnostic Studies

Most diagnostic cardiovascular studies are noninvasive and can be conducted safely in pregnant women. Conventional testing typically includes electrocardiography, echocardiography, and chest radiography. If indicated, heart catheterization can be performed with limited x-ray fluoroscopy.

Electrocardiography

There are several pregnancy-induced changes that need to be considered when interpreting an electrocardiogram. As the diaphragm is elevated in advancing pregnancy, for example, there is an average 15-degree left-axis deviation in the electrocardiogram, and mild ST changes may be seen in the inferior leads. Moreover, atrial and ventricular premature contractions are relatively frequent. Pregnancy does not alter voltage findings.

Echocardiography

The widespread use of echocardiography has allowed accurate and noninvasive diagnosis of most heart diseases during pregnancy. Some normal pregnancy-induced changes seen on echocardiography include tricuspid regurgitation and significantly increased left-atrial size and left-ventricular outflow cross-sectional area.

Chest X-Ray

Anteroposterior and lateral chest radiographs may be very useful when heart disease is suspected clinically. When used with a lead apron shield, fetal radiation exposure is minimized. Slight heart enlargement cannot be detected accurately by x-ray because the heart silhouette normally is larger in pregnancy; however, gross cardiomegaly can be excluded.

Clinical Classification

Two clinical classification schemes are commonly used for the evaluation of pregnant women with a history of heart disease. Shown in Table 48-2 is the classification system developed by the New York Heart Association. The classification system is useful to evaluate functional capacity and to aid in counseling the woman regarding advisability of conception or continuation of pregnancy.

TABLE 48-2. New York Heart Association Classification Scheme

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MANAGEMENT

Classes I and II

With rare exceptions, women in class I and most in class II go through pregnancy without morbidity, and mortality is rare. Throughout pregnancy and the puerperium, however, special attention should be directed toward both prevention and early recognition of heart failure. The onset of congestive heart failure is generally gradual. The first warning sign is likely to be persistent basilar rales, frequently accompanied by a nocturnal cough. A sudden diminution in ability to carry out usual duties, increasing dyspnea on exertion, and attacks of smothering with cough are symptoms of serious heart failure. Clinical findings may include hemoptysis, progressive edema, and tachycardia.

Infection has proved to be an important factor in precipitating cardiac failure. Each woman should receive instructions to avoid contact with persons who have respiratory infections, including the common cold, and report at once any evidence for infection. Pneumococcal and influenza vaccines are recommended. Bacterial endocarditis, moreover, is a deadly complication of valvular heart disease.

Cigarette smoking is prohibited, both because of its cardiac effects as well as the propensity to cause upper respiratory infections. Illicit drug use, especially intravenous, may be particularly harmful because of the direct cardiovascular effects as well as the risk of infective endocarditis.

Labor and Delivery

In general, delivery should be accomplished vaginally unless there are obstetrical indications for cesarean delivery. In some women with severe heart disease, pulmonary artery catheterization may be indicated for continuous hemodynamic monitoring. This may be performed electively when labor begins or planned cesarean delivery is performed. In our experiences, such monitoring is rarely indicated in women who have remained in functional class I or II throughout pregnancy.

Cardiovascular decompensation during labor may manifest as pulmonary edema and hypoxia, hypotension, or both. The proper therapeutic approach will depend upon the specific hemodynamic status and the underlying cardiac lesion. For example, decompensated mitral stenosis with pulmonary edema due to absolute or relative fluid overload is often best approached with aggressive diuresis, or if precipitated by tachycardia, by heart rate control with β-blocking agents. On the other hand, the same treatment in a woman suffering from decompensation and hypotension due to aortic stenosis could prove fatal. Unless the underlying pathophysiology is understood and the causes of the decompensation clear, empirical therapy is hazardous.

During labor, the mother with significant heart disease should be kept in a semirecumbent position with lateral tilt. Vital signs should be taken frequently between contractions. Increases in pulse rate much above 100 per minute or in the respiratory rate above 24, particularly when associated with dyspnea, may suggest impending ventricular failure. With any evidence of cardiac decompensation, intensive medical management must be instituted immediately. It is essential to remember that delivery itself will not necessarily improve the maternal condition. Moreover, emergency operative delivery may be particularly hazardous. Clearly, both maternal and fetal conditions must be considered in the decision to hasten delivery under these circumstances.

Anesthesia

Relief from pain and apprehension is especially important. Although intravenous analgesics provide satisfactory pain relief for some women, continuous epidural analgesia is recommended for most situations. The major danger of regional analgesia is maternal hypotension. This is especially dangerous in women with intracardiac shunts, in whom blood may flow from right-to-left within the heart and bypass the lungs. Hypotension can also be very hazardous with pulmonary hypertension or aortic stenosis because ventricular output is dependent upon adequate preload. In women with these conditions, narcotic regional analgesia or general anesthesia may be preferable.

For vaginal delivery in women with only mild cardiovascular compromise, epidural analgesia given along with intravenous sedation often suffices. This has been shown to minimize intrapartum cardiac output fluctuations and allows forceps or vacuum-assisted delivery. Subarachnoid blockage—spinal analgesia or saddle block—is not generally recommended in women with significant heart disease.

For cesarean delivery, epidural anesthesia is preferred by most clinicians with caveats for its use in patients with pulmonary hypertension. Spinal anesthesia is contraindicated with some lesions. Finally, general endotracheal anesthesia with thiopental, succinylcholine, nitrous oxide, and at least 30-percent oxygen has also proved satisfactory.

Puerperium

Women who have shown little or no evidence of cardiac distress during pregnancy, labor, or delivery may still decompensate after delivery. Therefore, it is important that meticulous care be continued into the puerperium. Postpartum hemorrhage, anemia, infection, and thromboembolism are much more serious complications with heart disease. Indeed, these factors frequently act in concert to precipitate postpartum heart failure in women with underlying heart disease.

If tubal sterilization is to be performed after vaginal delivery, it may be best to delay the procedure until it is obvious that the mother is afebrile, not anemic, and has demonstrated that she can ambulate without evidence of distress. Women who do not undergo tubal sterilization should be given detailed contraceptive advice.

Classes III and IV

The important question in these women is whether pregnancy should be undertaken. Those who choose to become pregnant must understand the risks and cooperate fully. If seen early enough, women with some types of severe cardiac disease should consider pregnancy termination. If the pregnancy is continued, prolonged hospitalization or bed rest will often be necessary.

As for less severe disease, epidural analgesia for labor and delivery is usually recommended. Vaginal delivery is preferred in most cases, and cesarean delivery is limited to obstetrical indications. The decision for cesarean delivery must take into account the specific cardiac lesion, overall maternal condition, and availability and experience of anesthetic support. These women often tolerate major surgical procedures poorly, and should be delivered in a facility having experience with complicated cardiac disease.

Surgically Corrected Heart Disease

A number of reproductive-aged women have had a prosthesis implanted to replace a severely damaged mitral or aortic valve. Successful pregnancies have followed prosthetic replacement of even three heart valves.

Women with a mechanical valve prosthesis must be anticoagulated, and when not pregnant, warfarin is recommended. Thromboembolism involving the prosthesis and hemorrhage from anticoagulation are of extreme concern. Overall, maternal mortality is 3 to 4 percent with mechanical valves, and fetal loss is common. Porcine tissue valves are much safer because anticoagulation is not required; however, valvular dysfunction, deterioration, or failure develop in 5 to 25 percent of pregnancies.

Contraception

Because of their possible thrombogenic action, estrogen–progestin oral contraceptives are relatively contraindicated in women with prosthetic valves. Sterilization should be considered because of the pregnancy risks faced by women with serious heart disease.

VALVULAR HEART DISEASE

Rheumatic fever is uncommon in the United States because of less crowded living conditions, availability of penicillin, and evolution of nonrheumatogenic streptococcal strains. Still, it remains the chief cause of serious mitral valvular disease.

Mitral Stenosis

Rheumatic endocarditis causes three-fourths of cases of mitral stenosis. The contracted valve impedes blood flow from the left atrium to the ventricle. With tight mitral stenosis, the left atrium is dilated. As shown in Table 48-3, left-atrial pressure is chronically elevated and may result in significant passive pulmonary hypertension as well as a fixed cardiac output. The increased preload of normal pregnancy, as well as other factors that require increased cardiac output, may cause ventricular failure with pulmonary edema. Indeed, 25 percent of women with mitral stenosis have cardiac failure for the first time during pregnancy.

TABLE 48-3. Major Cardiac Valve Disorders

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The normal mitral valve surface area is 4.0 cm2. When stenosis narrows this area to less than 2.5 cm2, symptoms usually develop. The most prominent complaint is dyspnea due to pulmonary edema and venous hypertension. Other common symptoms are fatigue, palpitations, cough, and hemoptysis.

In patients with significant mitral stenosis, tachycardia of any etiology shortens ventricular diastolic filling time and increases the mitral gradient, which raises left-atrial and pulmonary venous and capillary pressures and may result in pulmonary edema. Thus, sinus tachycardia is often treated prophylactically with β-blocking agents. Atrial tachyarrhythmias, including fibrillation, are common in mitral stenosis and are treated aggressively with cardioversion if necessary. Atrial fibrillation also predisposes to mural thrombus formation and aortic embolization, which may lead to a thrombotic cerebrovascular accident.

Management

Limited physical activity is generally recommended. If symptoms of pulmonary congestion develop, activity is restricted even more, dietary sodium is restricted, and diuretic therapy started. A β-blocker drug is often given to slow heart rate response to activity and anxiety. If new-onset atrial fibrillation develops, intravenous verapamil, 5 to 10 mg, is given, or electrocardioversion is performed. For chronic fibrillation, digoxin or a β- or calcium-channel blocker is given to slow ventricular response. Anticoagulation with heparin is also indicated (see Chapter 52).

Labor and delivery are particularly stressful for women with tight mitral stenosis. Pain, work, and anxiety cause tachycardia, with increasing chances of rate-related heart failure. Epidural analgesia for labor, with strict attention to avoid intravenous fluid overload, is ideal. Pulmonary capillary wedge pressures usually increase even more immediately postpartum. This is likely due to loss of the low-resistance placental circulation as well as “autotransfusion” from the lower extremities and pelvic veins and the now empty uterus. Abrupt increases in preload may also lead to increased pulmonary capillary wedge pressure and pulmonary edema. Thus, care must be taken to avoid fluid overload.

Vaginal delivery is preferable, and some authors recommend elective induction so that labor and delivery can be monitored and attended by the most knowledgeable team. In women with severe stenosis and chronic heart failure, insertion of a pulmonary artery catheter may help guide management decisions. Intrapartum endocarditis prophylaxis may be required (Table 48-4).

TABLE 48-4. American Heart Association Guidelines for Endocarditis Prophylaxis with Dental Procedures

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Mitral Insufficiency

Mitral regurgitation develops when there is improper coaptation of mitral-valve leaflets during systole, and this is eventually followed by left-ventricular dilatation and eccentric hypertrophy (see Table 48-3). Chronic mitral regurgitation may be due to a number of causes, including rheumatic fever, mitral-valve prolapse, or left-ventricular dilatation of any etiology—for example, dilated cardiomyopathy. Less common causes include a calcified mitral annulus, possibly some appetite suppressants, and in older women, ischemic heart disease. Acute mitral insufficiency is caused by rupture of a chorda tendineae, infarction of papillary muscle, or by leaflet perforation from infective endocarditis.

In nonpregnant patients, symptoms from mitral-valve incompetence are rare, and valve replacement is seldom indicated, except for infective endocarditis. Likewise, mitral regurgitation is well tolerated during pregnancy, probably due to decreased systemic vascular resistance, which actually results in less regurgitation. Heart failure only rarely develops during pregnancy, and occasionally tachyarrhythmias need to be treated. Intrapartum prophylaxis against bacterial endocarditis may be indicated (see Table 48-4).

Mitral-Valve Prolapse

The diagnosis of mitral-valve prolapse implies the presence of a pathological connective-tissue disorder—often termed myxomatous degeneration—which may involve the valve leaflets themselves, the annulus, or the chordae tendineae. The etiology of isolated myxomatous degeneration is unknown. Most women with mitral-valve prolapse are asymptomatic and are diagnosed by routine physical examination or as an incidental finding at echocardiography. The small percentage of women with symptoms has anxiety, palpitations, dyspnea, atypical chest pain, and syncope. Severe prolapse may increase the risk of sudden death, infective endocarditis, or cerebral embolism.

Effects on Pregnancy

Pregnant women with mitral-valve prolapse rarely have cardiac complications. In fact, pregnancy-induced hypervolemia may improve alignment of the mitral valve. For women who are symptomatic, β-blocking drugs are given to decrease sympathetic tone, relieve chest pain and palpitations, and reduce the risk of life-threatening arrhythmias. Mitral-valve prolapse with regurgitation, thickened leaflets, or both is considered to be a risk factor for bacterial endocarditis (see Table 48-4). Patients without evidence of pathological myxomatous change may, in general, expect excellent pregnancy outcome.

Aortic Stenosis

Stenosis of the aortic valve is a disease of aging, and in a woman younger than 30 years old, it is most likely due to a congenital lesion. The most common congenital stenotic lesion is a bicuspid valve. Stenosis reduces the normal 2 to 3 cm2 aortic orifice and creates resistance to ejection. A systolic pressure gradient develops between the left ventricle and the systemic arterial outflow tract. Concentric left-ventricular hypertrophy follows, and if severe, end-diastolic pressures become elevated, ejection fraction declines, and cardiac output is reduced (see Table 48-3). Characteristic clinical manifestations develop late and include chest pain, syncope, heart failure, and sudden death from arrhythmias. Life expectancy after exertional chest pain develops averages only 5 years, and valve replacement is indicated for symptomatic patients.

Clinically significant aortic stenosis is uncommonly encountered during pregnancy. Mild-to-moderate degrees of stenosis are well tolerated, but severe disease is life threatening. The principal underlying hemodynamic problem is the fixed cardiac output associated with severe stenosis. During pregnancy, a number of factors may be encountered that commonly decrease preload further and thus aggravate the fixed cardiac output. Some examples include blood loss, regional analgesia, and vena caval occlusion. Importantly, all of these factors decrease cardiac, cerebral, and uterine perfusion. Because of these considerations, severe aortic stenosis may be extremely dangerous during pregnancy. Patients with valve gradients exceeding 100 mm Hg appear to be at greatest risk.

Management in Pregnancy

For the asymptomatic pregnant woman, no treatment except close observation is required. Management of the symptomatic woman includes strict limitation of activity and prompt treatment of infections. If symptoms persist despite bed rest, valve replacement or valvotomy using cardiopulmonary bypass must be considered.

For women with critical aortic stenosis, intensive monitoring during labor is important. Pulmonary artery catheterization may be helpful because of the narrow margin separating fluid overload from hypovolemia. Patients with aortic stenosis are dependent upon adequate end-diastolic ventricular filling pressures to maintain cardiac output and systemic perfusion. Abrupt decreases in end-diastolic volume may result in hypotension, syncope, myocardial infarction, and sudden death. Thus, the key to the management of these women is the avoidance of decreased ventricular preload and maintenance of cardiac output. During labor and delivery, such women should be managed on the “wet” side, maintaining a margin of safety in intravascular volume in anticipation of unexpected hemorrhage.

During labor, narcotic epidural analgesia seems ideal, thus avoiding potentially hazardous hypotension, which may be encountered with standard regional analgesia techniques. Forceps or vacuum delivery is used for standard obstetrical indications in hemodynamically stable women. Bacterial endocarditis prophylaxis may be indicated during labor (see Table 48-4).

Aortic Insufficiency

Aortic regurgitation is the backward (diastolic) flow of blood from the aorta into the left ventricle. Common causes of aortic valvular incompetence are rheumatic fever, connective tissue abnormalities, and congenitally acquired lesions. With Marfan syndrome, the aortic root may dilate, resulting in aortic insufficiency. Acute insufficiency may develop with bacterial endocarditis or aortic dissection. Aortic as well as mitral-valve insufficiency have been linked to the appetite suppressants fenfluramine and dexfenfluramine.

With chronic disease, left-ventricular hypertrophy and dilatation develop (see Table 48-3). This is followed by slow-onset fatigue, dyspnea, and edema, although rapid deterioration usually follows. Aortic insufficiency is generally well-tolerated during pregnancy. Like mitral valve incompetence, diminished vascular resistance is thought to improve the lesion. Symptoms necessitate therapy for heart failure, including bed rest, sodium restriction, and diuretics. Epidural analgesia is used for labor as well as vaginal or cesarean delivery. Intrapartum bacterial endocarditis prophylaxis may be indicated (see Table 48-4).

INFECTIVE ENDOCARDITIS

This infection involves the cardiac endothelium and produces vegetations that usually deposit on a valve. Infective endocarditis can involve a native or a prosthetic valve, and it may be associated with intravenous drug abuse. Children and adults who survive corrective surgery for congenital heart disease are at greatest risk.

Acute Endocarditis

This is usually caused by coagulase-positive staphylococci. Staphylococcus aureus is the predominant organism in a third of native valve infections, and it causes half of those in intravenous drug abusers. In those not associated with drug use, the left side is involved in 80 percent of cases, and mortality is nearly 50 percent. Staphylococcus epidermidis commonly causes prosthetic valve infections. Streptococcus pneumoniae and Neisseria gonorrhoeaemay cause acute, fulminating disease.

Symptoms of endocarditis are variable and often develop insidiously. Fever is virtually universal, and a murmur is heard in 80 to 85 percent of cases. Anorexia, fatigue, and other constitutional symptoms are common, and the illness is frequently described as “flu-like.” Other findings are anemia, proteinuria, and manifestations of embolic lesions, including petechiae, focal neurological manifestations, chest or abdominal pain, and ischemia in an extremity. In some cases, heart failure develops. In the usual case, symptoms persist for several weeks before the diagnosis is made. Thus, a high index of suspicion is necessary to diagnose endocarditis. Diagnosis is confirmed by excluding other causes of febrile illnesses and recovering positive blood cultures. Echocardiography is useful, but lesions only 2 mm in size or those on the tricuspid valve may be missed. A negative echocardiographic study does not exclude endocarditis.

Treatment is primarily medical with appropriate timing of surgical intervention if this becomes necessary. Knowledge of the infecting organism is imperative for antimicrobial selection. Most viridans streptococci are sensitive to penicillin G given intravenously along with gentamicin for 2 weeks. Complicated infections are treated longer, and women allergic to penicillin are either desensitized or given intravenous ceftriaxone or vancomycin for 4 weeks. Staphylococci, enterococci, and other organisms are treated according to microbial sensitivity for 4 to 6 weeks. Prosthetic valve infections are treated for 6 to 8 weeks. Persistent native valve infection may require replacement, and this is even more commonly indicated with an infected prosthetic valve. Right-sided infections caused by methicillin-resistant S. aureus (MRSA) are treated with vancomycin.

Subacute Bacterial Endocarditis

This diagnosis refers to a low-virulence bacterial infection superimposed on an underlying heart lesion. These are usually native valve infections. Organisms that cause indolent bacterial endocarditis are most commonly viridans group streptococci or Enterococcus species.

Antimicrobial Prophylaxis

The American Heart Association recommends prophylaxis based on risk stratification (Table 48-4). The recommended prophylaxis regimens include intravenous or intramuscular administration of 2 g of ampicillin or 1 g of cefazolin or ceftriaxone. For penicillin-sensitive patients, one of the latter regimens is given, or if there is a history of anaphylaxis, then clindamycin, 600 mg is given intravenously. The recommended oral regimen is 2 g of amoxicillin. If enterococcus infection is of concern, vancomycin is also given.

PERIPARTUM CARDIOMYOPATHY

This is a diagnosis of exclusion and is similar to idiopathic dilated cardiomyopathy that occurs in nonpregnant adults. Although the term peripartum cardiomyopathy has been used widely to describe women with peripartum heart failure with no readily apparent etiology, it is doubtful that there is a specific pregnancy-induced cardiomyopathy. Diagnostic criteria are shown in Table 48-5. Because other causes must be excluded, careful evaluation of new-onset ventricular dysfunction is essential. In most cases, heart failure will ultimately be attributed to an underlying cause such as hypertensive heart disease, clinically silent mitral stenosis, obesity, or myocarditis. Regardless of the underlying condition that causes cardiac dysfunction, women who develop peripartum heart failure often have obstetrical complications (preeclampsia, acute anemia, infection) that either contribute to or precipitate heart failure.

TABLE 48-5. Diagnostic Criteria for Peripartum Cardiomyopathy

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Therapy consists of treatment for heart failure. Sodium intake is limited and diuretics are given to reduce preload. Afterload reduction with hydralazine or another vasodilator is accomplished; however, angiotensin-converting enzyme inhibitors should be avoided if the woman is undelivered. Digoxin is given for its inotropic effects unless complex arrhythmias are identified. Because there is a high incidence of associated pulmonary embolism, prophylactic heparin is often recommended.

Women with peripartum cardiomyopathy who regain ventricular function within 6 months have a good prognosis. But those who do not, however, have high morbidity and mortality rates.

Arrhythmias

Bradyarrhythmias, including complete heart block, are compatible with a successful pregnancy outcome. Some women with complete heart block have syncope during labor and delivery. Women with permanent artificial pacemakers usually tolerate pregnancy well.

Tachyarrhythmias are relatively common and should prompt consideration of underlying cardiac disease. Paroxysmal supraventricular tachycardia is encountered most frequently. If vagal maneuvers do not stimulate conversion, treatment consists of adenosine followed by calcium-channel or β-blocking drugs. Adenosine is safe and effective for cardioversion in hemodynamically stable pregnant women. Although these drugs do not appear to harm the fetus, fetal bradycardia with adenosine has been described. Electrical cardioversion is not contraindicated in pregnancy.

Atrial flutter or fibrillation is more likely associated with underlying disease, such as thyrotoxicosis or mitral stenosis. Major complications include stroke. Heparin is recommended by some if fibrillation is chronic and persists during pregnancy, especially if there is mitral stenosis. If atrial fibrillation is associated with mitral stenosis, pulmonary edema may develop in late pregnancy if the ventricular rate is increased.

PULMONARY HYPERTENSION

Primary pulmonary hypertension is rare and usually idiopathic. Suspected risk factors include certain appetite suppressants, human immunodeficiency virus, collagen-vascular disorders, antiphospholipid antibody syndrome, and thyrotoxicosis. Pulmonary hypertension—a hemodynamic observation and not a diagnosis—is defined in nonpregnant individuals as a mean pulmonary pressure greater than 25 mm Hg. Currently, classification of the World Health Organization is used. There are important prognostic and therapeutic distinctions between the classes. Class I indicates a specific disease that affects pulmonary arterioles. Class II disorders are more commonly encountered in pregnant women. These are secondary to pulmonary venous hypertension caused by left-sided atrial, ventricular, or valvular disorders. Class III is associated with lung disease, and class IV is due to chronic thromboembolic disease. Class V is a miscellaneous category.

Symptoms may be vague, and dyspnea with exertion is the most common. With class II disorders, orthopnea and nocturnal dyspnea are usually also present. Angina and syncope occur when right ventricular output is fixed, and they suggest advanced disease. Chest radiography commonly shows enlarged pulmonary hilar arteries and attenuated peripheral markings. It also may disclose parenchymal causes of hypertension. Diagnosis is by echocardiography and is confirmed by right-sided catheterization, which usually may be deferred during pregnancy.

Longevity depends on the cause and severity at discovery. For example, although invariably fatal, idiopathic pulmonary hypertension has a 3-year survival rate of 60 percent, whereas for collagen-vascular diseases, this rate is only 35 percent. Some disorders respond to pulmonary vasodilators, calcium-channel blockers, prostacyclin analogs, or endothelin-receptor blockers, all of which may improve quality of life. The prostacyclin analogs, epoprostenol and trepostinil, significantly lower pulmonary vascular resistance but must be given parenterally.

Eisenmenger syndrome refers to secondary pulmonary hypertension that develops with any cardiac lesion in which pulmonary vascular resistance becomes greater than systemic vascular resistance, resulting in right-to-left shunting. Patients are asymptomatic for years. After it develops, survival is 20 to 30 years. The prognosis for pregnancy depends on the severity of pulmonary hypertension. Women with Eisenmenger syndrome tolerate hypotension poorly, and the cause of death usually is right ventricular failure with cardiogenic shock.

Effects on Pregnancy

Maternal mortality is appreciable, especially with idiopathic pulmonary hypertension. Prognosis is dependent upon the etiology. Pregnancy is contraindicated with severe disease, especially those with pulmonary arterial changes—most class I. With milder degrees of other causes—class II being common—the prognosis is much better. Treatment of symptomatic pregnant women includes limitation of activity and avoidance of the supine position in late pregnancy. Diuretics, supplemental oxygen, and vasodilator drugs are standard therapy for symptoms.

Management of labor and delivery is particularly problematic. These women are at greatest risk when there is diminished venous return and right-ventricular filling. Regional analgesia is also problematic because of possible hypotension. Careful attention is given to blood loss at delivery.


For further reading in Williams Obstetrics, 23rd ed.,

see Chapter 44, “Cardiovascular Disease.”