Heart Disease in Pregnancy

Maternal Hemodynamics

Hemodynamics refers to the relationship between blood pressure, cardiac output, and vascular resistance. Blood pressure is measured by auscultation, use of an automated cuff, or directly with an intraarterial catheter. Cardiac output is measured by dilutional techniques requiring central venous access, by Doppler or two-dimensional echocardiographic techniques, or by electrical impedance. Peripheral resistance is calculated using Ohm's law:

where TPR is total peripheral resistance (dyne • s • cm ⁻⁵ ), MAP is mean arterial pressure (mm Hg), and CO is cardiac output (L/min).

Pregnancy and events unique to pregnancy, such as labor and delivery, are associated with significant and frequently predictable changes in these parameters. The hemodynamic changes of pregnancy, although well tolerated by an otherwise healthy woman, may be tolerated poorly by a woman with significant cardiac disease. Therefore the importance of understanding these changes and placing them in the context of a specific cardiac lesion cannot be overstated.

The maternal hemodynamics of 89 nulliparous women who remained normotensive throughout pregnancy are described in Fig. 42.1 . MAP falls sharply in the first trimester, reaching a nadir by midpregnancy. Thereafter, blood pressure increases slowly, reaching near nonpregnant levels by term. CO rises throughout the first and second trimesters, reaching a maximum by the middle of the third trimester. In the supine position, a pregnant woman in the third trimester may experience significant hypotension due to venacaval occlusion by the gravid uterus. In normal pregnancy, venacaval occlusion may produce symptoms such as diaphoresis, tachycardia, or nausea but will rarely result in significant complications. Fetal heart rate decelerations may be observed but usually resolve when the mother, often spontaneously, shifts to a more comfortable position. Women with significant right or left ventricular outflow obstruction, such as aortic stenosis, may seriously decompensate in the supine position due to poor ventricular filling.

CO is the product of heart rate (HR) and stroke volume (SV):

HR and SV increase as pregnancy progresses to the third trimester. After 32 weeks, SV falls, with the maintenance of CO becoming more and more dependent on HR. Vascular resistance falls in the first and early second trimesters. The magnitude of the fall is sufficient to offset the rise in CO, resulting in a net decrease in blood pressure.

Labor, delivery, and the postpartum period are times of acute hemodynamic changes that may result in maternal decompensation. Labor itself is associated with pain and anxiety. Tachycardia is a normal response. Significant catecholamine release increases afterload. Each uterine contraction acutely redistributes 400 to 500 mL of blood from the uterus to the central circulation. In Fig. 42.2 , Robson and colleagues describe the hemodynamic changes associated with unmedicated labor. HR, blood pressure, and CO all increase with uterine contractions, with the magnitude of the change increasing as labor advances. Obstructive cardiac lesions impede the flow of blood through the heart, blunting the expected rise in CO at the expense of increasing pulmonary pressures and pulmonary congestion. In Fig. 42.3 , intrapartum hemodynamic changes of a patient with aortic stenosis and a peak gradient of 160 mm Hg are shown. In this individual, pulmonary pressures rise in parallel with uterine contractions.

Immediately after delivery, blood from the uterus is returned to the central circulation. In normal pregnancy, this compensatory mechanism protects against the hemodynamic effects that may accompany postpartum hemorrhage. In the context of cardiac disease, this acute centralization of blood may increase pulmonary pressures and pulmonary congestion. During the first 2 postpartum weeks, extravascular fluid is mobilized, diuresis ensues, and vascular resistance increases, returning to nonpregnant norms. Decompensation during postpartum fluid mobilization is common in women with mitral stenosis. Volume loading coupled with vasoconstriction may also unmask maternal cardiomyopathy. Unsuspected cardiac disease may be diagnosed when a woman returns to the emergency room several days postpartum with dyspnea and oxygen desaturation. Maternal CO usually normalizes by 2 weeks postpartum.

Three key features of the maternal hemodynamic changes in pregnancy are particularly relevant to the management of women with cardiac disease: (1) increased CO, (2) increased HR, and (3) reduced vascular resistance. In conditions such as mitral stenosis, in which CO is relatively fixed, the drive to achieve an elevated CO may result in pulmonary congestion. If a patient has an atrial septal defect, the incremental increase in systemic flow associated with pregnancy will be magnified in the pulmonary circulation to the extent that pulmonary flow exceeds systemic flow. If, for example, a shunt ratio of 3 : 1 is maintained in pregnancy, pulmonary flow may be as high as 20 L/min and may be associated with increasing dyspnea and potential desaturation.

Many cardiac conditions are HR dependent. Flow across a stenotic mitral valve is dependent on the proportion of time in diastole. Tachycardia reduces left ventricular filling and CO. Coronary blood flow is also dependent on the length of diastole. Patients with aortic stenosis have increased wall tension and, therefore, increased myocardial oxygen requirements. Tachycardia reduces coronary perfusion time in diastole while simultaneously further increasing myocardial oxygen requirements. The resulting imbalance between oxygen demand and supply may precipitate myocardial ischemia. Patients with complex congenital heart disease can experience significant tachyarrhythmias. The increasing HR in pregnancy may be associated with a worsening of tachyarrhythmias.

Reduction in vascular resistance may be beneficial to some patients; afterload reduction reduces cardiac work. Cardiomyopathy, aortic regurgitation, and mitral regurgitation all benefit from reduced afterload. Alternatively, patients with intracardiac shunts, in which right and left ventricular pressures are nearly equal when not pregnant, may reverse their shunts during pregnancy and desaturate because of right-to-left shunting.

Blood Volume

Very early in the first trimester, pregnant women experience an expansion of renal blood flow and glomerular filtration rate. Filtered sodium increases by about 50%. Despite physiologic changes that would promote loss of salt and water and contraction of blood volume, the pregnant woman will expand her blood volume by 40% to 50%. In part, the stimulation to retain fluid may be a response to the fall in vascular resistance and reduction in blood pressure. The renin-angiotensin system is activated, and the plasma concentration of aldosterone is elevated. Although the simplicity of this explanation is attractive, the actual process is probably much more complicated.

As plasma volume expands, the hematocrit falls, and hematopoiesis is stimulated. Red cell mass will expand from 18% to 25% depending on the status of individual iron stores. Physiologic anemia with a maternal hematocrit between 30% and 35% does not usually complicate pregnancy in the context of maternal heart disease. More significant anemia, however, may increase cardiac work and induce tachycardia. Microcytosis due to iron deficiency may impair perfusion of the microcirculation of patients who are polycythemic because of cyanotic heart disease because microcytic red blood cells are less deformable. Iron and folate supplementation may be appropriate.

In a similar fashion, serum albumin concentration falls by 22% despite an expansion of intravascular albumin mass by 20%. Hence serum oncotic pressure falls in parallel by 20%. In normal pregnancy, intravascular fluid balance is maintained by a fall in interstitial oncotic pressure. However, if left ventricular filling pressure becomes elevated or if pulmonary vascular integrity is disrupted, pulmonary edema will develop earlier in the disease process than in nonpregnant women.

Diagnosis and Evaluation of Heart Disease

Many women with heart disease have been diagnosed and treated before pregnancy with available records for review. Others report only that they have a murmur or a “hole in my heart.” Alternatively, heart disease may be diagnosed for the first time during pregnancy owing to symptoms precipitated by increased cardiac demands.

The classic symptoms of cardiac disease are palpitations, shortness of breath with exertion, and chest pain. Because these symptoms also may accompany normal pregnancy, a careful history is needed to determine whether the symptoms are out of proportion to the stage of pregnancy. Symptoms are of particular concern in a patient with other reasons to suspect underlying cardiac disease, such as being native to an area where rheumatic heart disease is prevalent.

A systolic flow murmur is present in 80% of pregnant women, most likely due to the increased flow volume in the aorta and pulmonary artery. Typically, a flow murmur is grade 1 or 2, midsystolic, loudest at the cardiac base, and not associated with any other abnormal physical examination findings. A normal physiologic split second heart sound is heard in patients with a flow murmur. Any diastolic murmur and any systolic murmur that is loud (grade 3/6 or higher) or radiates to the carotids should be considered pathologic. Careful evaluation for elevation of the jugular venous pulse, for peripheral cyanosis or clubbing, and for pulmonary crackles is needed in women with suspected cardiac disease.

Indications for further cardiac diagnostic testing in pregnant women include a history of known cardiac disease, symptoms in excess of those expected in a normal pregnancy, a pathologic murmur, evidence of heart failure on physical examination, or arterial oxygen desaturation in the absence of known pulmonary disease. The preferred next step in evaluation of pregnant women with suspected heart disease is transthoracic echocardiography. A chest radiograph is helpful only if congestive heart failure is suspected. An electrocardiogram (ECG) may be nonspecific but could have changes suggestive of the underlying heart disease, such as right ventricular hypertrophy and biatrial enlargement, seen in patients with significant mitral stenosis. If symptoms are consistent with a cardiac arrhythmia, a 24- to 48-hour ECG monitor or long-term event monitoring may be indicated. Cardiac catheterization is rarely needed for full diagnosis of valvular or congenital heart disease, although it may be indicated for acute coronary syndrome during pregnancy; the risk for radiation exposure with cardiac catheterization is small compared with the benefit of early diagnosis and early revascularization to prevent myocardial infarction (MI).

Echocardiography provides detailed information on cardiac anatomy and physiology that allows optimal management of women with heart disease. Basic data obtained on echocardiography include left ventricular ejection fraction, pulmonary artery systolic pressure, qualitative evaluation of right ventricular systolic function, and evaluation of valve anatomy and function. When valvular stenosis is present, the pressure gradient (Δ P ) across the valve is calculated from the Doppler-derived velocity (v) of flow across the valve: Δ P = 4v ² . Similarly, pulmonary artery systolic pressure can be calculated from the maximal Doppler velocity obtained across a tricuspid regurgitant jet.

Aortic valve area is calculated using the continuity equation. SV is calculated from the product of the cross-sectional area of the left ventricular outflow tract and the time-velocity integral derived from Doppler evaluation of the outflow tract. A time-velocity integral is then derived from the stenotic valve. Because the left ventricular outflow tract and the aortic valve are in continuity, SVs across each are equal. Therefore valve area can be derived by dividing the stroke volume by the aortic valve time-velocity integral. Mitral valve area is measured directly by two-dimensional planimetry or by the Doppler pressure half-time method. In patients with congenital disease, detailed evaluation of anatomy and previous surgical repair is possible. When complex congenital heart disease is present or when image quality is suboptimal, transesophageal imaging provides improved image quality. Cardiac magnetic resonance imaging may be used to define complex anatomy that is not well evaluated by echocardiography, but caution must be taken with magnetic resonance contrast agents such as gadolinium.

Serum levels of B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP) rise in response to volume loading conditions and have been used outside pregnancy as predictors of adverse outcomes in patients with cardiac disease. Serum levels of BNP ≤100 pg/mL and NT-proBNP ≤125 pg/mL have been demonstrated to have strong negative predictive values for adverse cardiac outcomes in pregnant women with heart disease. In our practice, we use BNP to identify potentially adverse effects of volume loading in pregnancy and to guide therapy. Fig. 42.4 describes the course of serum BNP levels across two pregnancies in a woman with hypertrophic cardiomyopathy. The time frame of each of the pregnancies is easily identifiable by marked rise in BNP. The impact of the initiation and dose adjustments in diuretic therapy with furosemide can be identified by sharp reductions in BNP.

General Care

Management of cardiac disease in pregnancy is frequently complicated by unique social and psychologic concerns. Children with congenital heart disease may have experienced multiple hospitalizations and be fearful of the medical environment. Some have been cautioned against pregnancy and, therefore, have never expected to bear children. Women with rheumatic heart disease have frequently lived outside the traditional medical care system owing to conditions of poverty, immigration, and cultural differences. Care must be exercised to facilitate their access to care and their comfort with the environment of care. Their practitioner must be patient but persistent in the face of deviations from more traditional standards of compliance and medical care.

Deterioration in cardiac status during pregnancy is frequently insidious. Continuity of care with a single provider facilitates early intervention before overt decompensation. Regular visits should include particular attention to HR, weight gain, and oxygen saturation. An unexpected increase in weight may indicate the need for more aggressive outpatient therapy. A fall in oxygen saturation often precedes a clearly abnormal chest examination or radiograph. Regular use of a structured history of symptoms ( Box 42.1 ) alerts the physician to a change in condition. Regular review also educates the patients and reinforces their collaborative roles as “partners in care.”

The physiologic changes of pregnancy are usually continuous and, therefore, offer adequate time for maternal compensation despite cardiac disease. Intercurrent events superimposed on pregnancy in the context of maternal heart disease are usually responsible for acute decompensation. The most common significant intercurrent events during the antepartum period are febrile episodes. Screening for bacteriuria and vaccination against influenza and pneumococcus are appropriate. Patients should be instructed to report symptoms of upper respiratory infection, particularly fever. Many women with heart disease (adolescents, recent immigrants, and those living in poverty) are also at risk for iron deficiency. Prophylaxis against anemia with iron and folate supplementation may decrease cardiac work.

A strategy of standard cardiac care for labor and delivery is described in Box 42.2 . The peripartum management of women with significant heart disease requires a multidisciplinary team that generally includes a maternal-fetal medicine specialist, obstetric anesthesiologists, and cardiologists. Given their complexity, these women should be delivered at higher-level facilities; the general principles for care are similar for most cardiac diagnoses. Physiologically, the ideal labor for a woman with heart disease is short and pain free. Although induction of labor facilitates organization of care and early pain control, one must balance the risks of prolonged induction with benefits of earlier delivery. Induction of labor with a favorable cervix is, therefore, preferred. Some patients with severe cardiac disease benefit from invasive hemodynamic monitoring with an arterial catheter and a pulmonary artery catheter. These methods are discussed in detail later. Cesarean delivery is usually reserved for obstetric indications. The American Heart Association (AHA) does not recommend routine antibiotic prophylaxis for the prevention of endocarditis.

Women with significant heart disease should be counseled before pregnancy regarding the risk of pregnancy, interventions that may be required, and potential risks to the fetus. In this situation, the risks and benefits of termination of pregnancy versus those of continuing a pregnancy should be addressed. The decision to become pregnant or carry a pregnancy in the context of maternal disease is a balance of two forces: (1) the objective medical risk, including the uncertainty of that estimate, and (2) the value of the birth of a child to an individual woman and her partner. The first goal of counseling is to educate the patient and her partner. Only a few cardiac diseases represent an overwhelming risk for maternal mortality: Eisenmenger syndrome, pulmonary hypertension with right ventricular dysfunction, and Marfan syndrome with significant aortic dilation and severe left ventricular dysfunction. Most other conditions require aggressive management and significant disruption in lifestyle. Intercurrent events such as antepartum pneumonia or obstetric hemorrhage pose the greatest risk for initiating life-threatening events. Fastidious care can reduce but not eliminate the risk for these events. Fetal risks of heart disease should also be discussed. Maternal congenital heart disease increases the risk for congenital heart disease in the fetus from 1% to about 4% to 6%. Marfan syndrome and some forms of hypertrophic cardiomyopathy are inherited as autosomal dominant conditions; the offspring of these women carry a 50% chance of inheriting the disease. The second goal of counseling is to help each woman integrate the medical information into her individual value system and her individual desire to become a mother. Many women with significant but manageable heart disease choose to carry a pregnancy.

Risk Scoring Strategies

Pregnancy in women with heart disease is associated with an increased risk for deterioration of maternal cardiac status and adverse pregnancy outcomes. These risks include maternal arrhythmias, heart failure, preterm birth, fetal growth restriction, and a small but notable risk of maternal and fetal mortality. Accurate quantification of maternal and fetal risks could be used to counsel patients and to direct care. Three risk models have been suggested.

The CARPREG score was derived from a prospective descriptive study of 562 pregnant women with cardiac disease with congenital or acquired lesions including arrhythmias. The scoring system was created to estimate risk of experiencing a primary cardiac event. The predictors in this scoring system include: (1) a prior cardiac event (heart failure, transient ischemic attack or stroke before pregnancy); (2) baseline New York Heart Association (NYHA) class greater than II or cyanosis; (3) mitral valve area less than 2 cm ² , aortic valve area less than 1.5 cm ³ , or peak left ventricular outflow tract gradient greater than 30 mm Hg by echocardiography; and (4) reduced systemic ventricular systolic function with an ejection fraction of less than 40%.

The ZAHARA score was derived from a nationwide database of 1302 pregnant women with congenital heart disease. Predictors identified to be associated with maternal cardiac complications included (1) prior arrhythmia, (2) NYHA class III/IV, (3) LVOT gradient greater than 50 mm Hg or aortic valve area less than 1.0 cm ² , (4) mechanical valve prosthesis, (5) systemic AV valve regurgitation (moderate/severe), (6) pulmonary AV valve regurgitation (moderate to severe), (7) cardiac medication prior to pregnancy, and (8) cyanotic heart disease, both corrected and uncorrected. This study also externally validated the prior CARPREG study and noted that the CARPREG score overestimated the risk.

The modified World Health Organization (WHO) classification uses four categories determined largely by diagnosis: class I—uncomplicated, mild pulmonary stenosis; class II—unoperated ASD or VSD and repaired tetralogy of Fallot; class III—mechanical valves, systemic right ventricle, Fontan circulation, unrepaired cyanotic heart disease, other complex congenital heart disease, Marfan syndrome with an aorta 40 to 45 mm in width, and bicuspid aortic valve with aorta 45 to 50 mm; and class IV—pulmonary hypertension/Eisenmenger syndrome, systemic EF less than 30%, systemic dysfunction NYHA class III–IV, severe mitral stenosis, severe symptomatic aortic stenosis, Marfan syndrome with aorta greater than 45 mm, bicuspid valve with aorta greater than 50 mm, and native severe coarctation ( Table 42.1 , Box 42.3 ).

The ZAHARA II study was performed to validate and compare CARPREG, ZAHARA 1, and the modified WHO risk models for pregnant women with congenital heart disease. ZAHARA II enrolled 234 women and included only patients with congenital structural heart disease. Overall, primary cardiovascular events were observed in 22 of the pregnancies (10.3%). The most frequent events included clinically significant arrhythmias, followed by heart failure and thrombotic events. It was noted that the ZAHARA 1 and CARPREG scores overestimated risk. The modified WHO classification performed as the best available risk assessment model for estimating cardiovascular risk.

From the scoring systems, common features can be identified that individually or collectively may predict adverse outcome. For patients with several risk factors, the impact on outcome may be more than additive as suggested by the structures of the scoring systems: (1) prior cardiac event, (2) NYHA class III/IV, (3) LVOT obstruction, (4) reduced systemic EF, (5) mechanical prosthesis, (6) moderate to severe AV valve regurgitation, (7) cardiac medications prior to pregnancy, and (8) cyanotic heart disease. The WHO system based on diagnoses incorporates risk associated with pulmonary hypertension and right ventricular dysfunction, severe mitral stenosis, dilated aortas, and single ventricle repairs not specifically captured by CARPREG or ZAHARA.

Although it seems optimal to be able to assign a direct risk score to a woman in counseling her during pregnancy, all of the studies above highlight the challenge in being able to create the ideal scoring system. Each category of congestive heart failure carries varied risks based on maternal hemodynamic and cardiovascular function findings. Therefore, although it is important to understand the different risk scores, ultimately individual cardiovascular functional parameters and overall hemodynamic stability of each patient are necessary to provide the most individualized care for each woman.

Valvular Disease

The American College of Cardiology (ACC) and the AHA have published guidelines for the management of valvular heart disease, including some guidelines for management during pregnancy. These guidelines create a general framework for preconception care and counseling, and care during pregnancy, realizing that treatment of a specific patient must be individualized.

Mitral Stenosis

Mitral stenosis is most commonly caused by rheumatic heart disease and is the most common acquired valvular lesion in pregnant women . Valvular dysfunction progresses continuously throughout life. Deterioration may be accelerated by recurrent episodes of rheumatic fever. Rheumatic fever itself is an immunologic response to group A β-hemolytic streptococcus infections. The incidence of rheumatic fever in a population is heavily influenced by conditions of poverty and crowding. These same individuals are at risk for having reduced access and use of healthcare resources and may present undiagnosed or untreated.

Patients with asymptomatic mitral stenosis have a 10-year survival rate of greater than 80%. Once a patient is significantly symptomatic, the 10-year survival rate without treatment is less than 15%. In the presence of pulmonary hypertension, mean survival falls to less than 3 years. Death is due to progressive pulmonary edema, right-sided heart failure, systemic embolization, or pulmonary embolism.

Stenosis of the mitral valve impedes the flow of blood from the left atrium to the left ventricle during diastole. The normal mitral valve area is 4 to 5 cm ² . Symptoms with exercise can be expected with valve areas less than or equal to 2.5 cm ² . Symptoms at rest are expected at less than or equal to 1.5 cm ² . The left ventricle responds with Starling mechanisms to increased venous return with increased performance, elevating CO in response to demand. The left atrium is limited in its capacity to respond. Therefore CO is limited by the relatively passive flow of blood through the valve during diastole; increased venous return results in pulmonary congestion rather than increased CO. Thus the drive for increased CO in pregnancy cannot be achieved, resulting in increased pulmonary congestion. The relative tachycardia experienced in pregnancy shortens diastole, decreases left ventricular filling, and, therefore further compromises CO and increases pulmonary congestion.

The diagnosis of mitral stenosis in pregnancy before maternal decompensation is uncommon. Fatigue and dyspnea on exertion are characteristic symptoms of mitral stenosis but are also ubiquitous among pregnant women. Although the presence of a diastolic rumble may suggest mitral stenosis, this finding is subtle and may be overlooked or not appreciated. Not uncommonly, an intercurrent event such as a febrile episode will result in exaggerated symptoms and the diagnosis of pulmonary edema or oxygen desaturation. Under these circumstances, particularly in the context of a patient from an at-risk group, an echocardiogram should be performed to rule out mitral-valvular disease.

Echocardiographic diagnosis of mitral stenosis is based on the characteristic appearance of the stenotic, frequently calcified valve. Calculation of valve area from pressure half-time of the Doppler wave or by two-dimensional planimetry provides an objective measure of severity. Valve areas of 1 cm ² or less usually require pharmacologic management during pregnancy and invasive hemodynamic monitoring during labor. Valve areas of 1.4 cm ² or less usually require careful expectant management. Recent data from the Registry of Pregnancy and Cardiac Disease (ROPAC) evaluated 273 women with mitral stenosis, of whom 19.8% had severe disease. Although the mortality rate was only 1.9% during pregnancy, 50% of the women had heart failure or had a significant cardiac event, suggesting that prepregnancy counseling and consideration of valve interventions are crucial.

Left atrial enlargement identifies a patient at risk for atrial fibrillation, subsequent atrial thrombus, and the potential for systemic embolization. Embolic complications have been reported in pregnant women with atrial enlargement without atrial fibrillation. Pulmonary hypertension, a complication of worsening mitral disease, can be diagnosed and quantified with Doppler evaluation of the regurgitant jet across the tricuspid valve. Elevated pulmonary pressures may be due to hydrostatic forces associated with elevated left atrial pressures or, in more advanced disease, may result from pathologic elevations of pulmonary vascular resistance (PVR). Hydrostatic pulmonary hypertension may respond to therapy that lowers left atrial pressure. Pulmonary hypertension due to elevated PVR is life threatening in pregnancy and may precipitate right-sided heart failure in the postpartum period.

Pregnancy itself does not negatively affect the natural history of mitral stenosis. Chesley reviewed the medical histories of 134 women with functionally severe mitral stenosis who survived pregnancies between 1931 and 1943. These women lived before modern management of mitral stenosis and, therefore, represent the natural history of the disease. By 1974, only nine of the cohort remained alive. Their death rate was exponential; during each year of follow-up, the rate for the remaining cohort was 6.3%. Women with subsequent pregnancies had comparable survival to those who did not again become pregnant, allowing the authors to conclude that pregnancy itself did not negatively affect long-term outcome.

The goal of antepartum care in the context of mitral stenosis is to achieve a balance between the drive to increase CO and the limitations of flow across the stenotic valve. Most women with significant disease require diuresis with a drug such as furosemide. In addition, β-blockade reduces HR, improves diastolic flow across the valve, and relieves pulmonary congestion . Al Kasab and associates evaluated the impact of β-blockade on 25 pregnant women with significant mitral stenosis. Fig. 42.5 describes the functional status of women before pregnancy, during pregnancy before β-blockade, and after β-blockade. The deterioration associated with pregnancy and the subsequent improvement with treatment is evident. Fastidious antepartum care as described earlier should supplement pharmacologic management.

Women with a history of rheumatic valvular disease, who are at risk for contact with populations with a high prevalence of streptococcal infection, should receive prophylaxis with daily oral penicillin G or monthly benzathine penicillin. Most pregnant women live in close contact with groups of children and usually are considered at risk.

Atrial fibrillation is a complication associated with mitral stenosis due to left atrial enlargement. Rapid ventricular response to atrial fibrillation may result in sudden decompensation. Digoxin, β-blockers, or calcium channel blockers can be used to control ventricular response. In the context of hemodynamic decompensation, electrical cardioversion may be necessary. Anticoagulation with heparin should be used before and after cardioversion to prevent systemic embolization. Patients with chronic atrial fibrillation and a history of an embolic event should receive prophylactic anticoagulation. Anticoagulation may be considered in women with a left atrial dimension of 55 mm Hg or greater.

Labor and delivery can frequently precipitate decompensation in patients with critical mitral stenosis. Pain induces tachycardia. Uterine contractions increase venous return and, therefore, pulmonary congestion. Women frequently cannot tolerate the work of pushing in the second stage. Clark and coworkers described the abrupt elevation in pulmonary artery pressures in the immediate postpartum period associated with return of uterine blood to the general circulation ( Fig. 42.6 ). Aggressive, anticipatory diuresis will reduce pulmonary congestion and the potential for oxygen desaturation.

The hemodynamics of women with symptomatic stenosis or a valve area of 1 cm ² or less may benefit from management with the aid of a pulmonary artery catheter. Ideally, hemodynamic parameters are assessed when the patient is well compensated, early in labor. These findings serve as a reference point to guide subsequent therapy. Pain control is best achieved with an epidural. HR control is maintained through pain control and β-blockade. To avoid pushing, the second stage is shortened with low or outlet forceps or vacuum delivery. Aggressive diuresis is initiated immediately postpartum. Cesarean delivery is reserved for obstetric indications. In a series of 80 pregnancies managed with a range of severity, the most common complications were pulmonary edema (31%) and arrhythmia (11%). When valve area was 1 cm ² or less, the rate of pulmonary edema was higher (56%), as was the rate of arrhythmia (33%). These rates will be dependent on the effectiveness of medical management and the timing of presentation and diagnosis.

Aggressive medical management, including inpatient antepartum admission, is sufficient to manage most women with mitral stenosis. The woman with uncommonly severe disease may require surgical intervention. Although successful valve replacement and open commissurotomy have been reported in pregnancy, they are now rarely needed. Successful mitral valvuloplasty in pregnancy has been reported: two recent reports detail successful balloon valvotomy in a series of 38 and 71 women with minimal complications. Outside of pregnancy, complications occur at the following rates: mortality (0.5%), cerebrovascular accident (1%), and mitral regurgitation requiring surgery (2%). However, despite the overall success rates of valvuloplasty in pregnancy, medical management should be clearly exhausted before assuming these risks during pregnancy, when emergent intervention such as valve replacement is more complicated and carries a significant risk to the fetus.

Rheumatic disease can also affect the aortic valve. Management of significant mitral stenosis, which limits ventricular filling, in the context of aortic stenosis that is critically dependent on ventricular filling, is particularly complicated.