Cardiac Diseases in Pregnancy



Cardiac Diseases in Pregnancy


Ji Eun Park

Charles C. Hong

Susie N. Hong



Introduction

Pregnancy causes significant alterations in the maternal cardiovascular system such as increased circulating blood volume and increased cardiac output. Women who are pregnant and have normal cardiac function can accommodate these physiologic changes without difficulty. However, in the presence of cardiac disease, pregnancy can result in heart failure (HF), arrhythmias, and thromboembolic events, leading to progressive maternal cardiac dysfunction and even death. Advances in cardiovascular medicine and cardiothoracic surgery have improved long-term outcomes in patients with congenital heart disease (CHD), and as such, most patients with CHD reach childbearing age. Given an observed increasing prevalence of pregnancies among women with cardiovascular disease, estimated to range between 0.1% and 4%, the need for obstetricians to be well-versed in proper counseling and management of these conditions is paramount.1 Despite advances in the diagnosis and management of maternal cardiovascular disease, such conditions continue to account for 15% of maternal deaths in pregnancy.2 This chapter focuses on the interaction between structural cardiovascular disease and pregnancy, with an emphasis on the means of achieving optimal maternal and perinatal outcomes.


Clinical Assessment of the Cardiac Patient During Pregnancy

Prepregnancy counseling in women with cardiac disease is ideal to individualize peripartum cardiac risk. The World Health Organization (WHO) classification of maternal cardiovascular risk (Table 28.1) provides a lesion-based maternal risk assessment that is widely utilized.3,4 Low-risk lesions are designated WHO I, medium-risk lesions are WHO II, high-risk lesions are WHO III, and lesions in which pregnancy is contraindicated are WHO IV. The WHO classification takes into account the New York Heart Association (NYHA) classification of HF based on clinical function (classes I-IV, Table 28.2). NYHA class I describes patients whose physical activity is not limited by symptoms such as dyspnea or fatigue. Class II includes those who are comfortable at rest but are limited in their usual activities by symptoms. Class III patients have symptoms with marked limitation in their usual activities, while class IV describes patients with symptoms at rest. In general, women who begin pregnancy as functional class I or II have a better outcome than those initially in class III or IV.5,6

Several large cohort studies have described pregnancy risk indices in an effort to better classify higher risk pregnancies. Of those, the Cardiac Disease in Pregnancy (CARPREG) study identified four predictors of maternal cardiac events: prior cardiac event or arrhythmias, poor functional status (NYHA class III or IV) or cyanosis, high-risk left-sided valvular lesion or obstruction, and left ventricular (LV) systolic dysfunction (ejection fraction [EF] < 40%).7 The predictors were further evaluated in CARPREG II, with the addition of lesion-specific variables (mechanical prosthesis, coronary artery disease, high-risk aortopathy, and pulmonary hypertension [PH]) and late pregnancy assessment into a risk score.8 A score of 0 to 1 points predicted 5% cardiac risk, 2 points predicted 10% risk, 3 points predicted 15% risk, 4 points predicted 22% risk, and >4 points predicted 41% risk or higher. The Boston Adult Congenital Heart group found reduced right ventricular (RV) function and severe pulmonic regurgitation (PR) were predictors of adverse cardiac outcomes in pregnancy.9 Additionally, the ZAHARA (Zwangerschap bij Aangeboren HARtAfwijking) study investigated outcomes with particular interest in women with
CHD, finding that moderate to severe aortic or pulmonic valve regurgitation, presence of a mechanical valve prosthesis, and cyanotic heart disease were independent predictors of adverse outcomes.10 The WHO classification, incorporating these predictors from the above studies, has been validated in pregnant women with heart disease, both in resource-rich and resource-limited settings.11,12








These studies have shown that, although women with cardiac disease have significant morbidity, maternal mortality is rare at <1%.7,8,11,13,14 However, maternal mortality is higher in women with heart disease compared to the general population.13,15,16 Although somewhat dated, a study by de Swiet, reporting on maternal mortality from heart disease in the United Kingdom between 1997 and 1999,
found that all deaths could be accounted for from the following entities: peripartum cardiomyopathy (PPCM) (20%), myocardial infarction (MI) (14%), aortic dissection (14%), cardiomyopathy and myocarditis (14%), primary PH (9%), secondary PH (11%), endocarditis (9%), and dysrhythmia (3%).17 Prior to this, a review of maternal mortality in Utah from 1982 to 1994 revealed 13 cardiac deaths, 4 from PH (31%), 4 secondary to cardiomyopathy (31%), 2 from coronary artery disease (15%), and 3 from sudden arrhythmia (23%), indicating the relative stability of etiologies of maternal mortality.16 Notably, up to 40% of patients developing HF and pulmonary edema during pregnancy are NYHA functional class I before pregnancy. In one review, the majority of maternal deaths during pregnancy occurred in patients who were initially NYHA class I or II, likely representing the small number of pregnant patients with NYHA class III or IV HF.5 However, not all clinical variables can be captured through risk predictors or indices, and individual patient risk assessment based on clinical judgment remains crucial to providing the best possible pre-, peri-, and antenatal patient care.









Specific Maternal Cardiac Diseases Affecting Pregnancy


Arrhythmias


Clinical Presentation

Pregnancy, especially in the setting of cardiac disease, may increase the risk of arrhythmias and arrhythmia exacerbation. Supraventricular tachycardias (SVTs), as well as atrial fibrillation and atrial flutter, are more common in pregnancies in women with CHD than in women without CHD. Importantly, although generally well tolerated (WHO risk class II), adverse maternal and fetal outcomes have been described with SVT in pregnancy, emphasizing the need for treatment.3,18


Epidemiology

In a review of 2491 pregnancies in women with CHD, 4.5% of pregnancies were complicated by clinical significant arrhythmias.19 Of those, 68% were SVTs and 13% were ventricular arrhythmias.



Congenital Cardiac Diseases

The relative frequency of CHD is changing.15,21 With the wide introduction of efficacious penicillin therapy for rheumatic fever, subsequent valvular stenosis is relatively uncommon in the United States. Concomitant advances in cardiovascular intervention and cardiothoracic surgery have enabled the surgical correction of many previously fatal congenital cardiac lesions. Thus, patients with CHD now account for the vast majority of pregnant women with heart disease. In a review in 1954, the ratio of rheumatic to CHD seen during pregnancy was 16:1; the current ratio approximates 1:1.5.14,15,22,23,24 The discussion here focuses on aspects of congenital cardiac disease that are unique to pregnancy. In a review of almost 2500 pregnancies in women with CHD, there were cardiac complications in 11%.19 We preface our discussion regarding congenital
cardiac lesions with the acknowledgment that patients at risk of developing right-to-left shunts with increased PH are at highest risk for unacceptably high maternal and fetal morbidity and mortality; surgical correction prior to the development of increased pulmonary vascular resistance and PH (Eisenmenger syndrome) is the greatest single contributor to improved outcomes observed over the preceding 4 decades.


Atrial Sepal Defects


Clinical Presentation

Atrial septal defects (ASDs) are the most common congenital lesions seen during pregnancy and are generally asymptomatic.25,26 As a result of the disproportionate number of women with ostium secundum defects being asymptomatic until the reproductive years, it is not unheard of to have women present with a sentinel ASD diagnosis in pregnancy.27 The two significant potential complications seen with ASDs are arrhythmias and right atrial and/or ventricular enlargement.

As a result of pregnancy-associated increases in atrial volume, biatrial enlargement and resultant supraventricular dysrhythmias are occasionally encountered. In general, although atrial arrhythmias are not uncommon in patients with ASDs, their onset generally occurs after the fourth decade of life. Thus, such arrhythmias are unlikely to be encountered in the majority of pregnant women. That said, in patients with ASDs, atrial fibrillation is the most common arrhythmia encountered; however, SVT and atrial flutter also may occur.28

In contrast to the high-pressure/high-flow state seen with ventricular septal defect (VSD) and patent ductus arteriosus (PDA), ASDs are characterized by high pulmonary blood flow associated with normal pulmonary artery pressures. Because pulmonary artery pressures are low, PH is unusual.


Clinical Assessment

The hypervolemia and increased cardiac output associated with pregnancy accentuates the left-to-right shunt through the ASD, increasing the burden on the right ventricle. Those with impaired functional capacity, right atrial or RV enlargement, or a left-to-right shunt large enough to cause physiologic sequelae (pulmonary to systemic blood flow ratio Qp:Qs ≥ 1.5:1) should be evaluated for surgical or transcatheter closure prior to conception.1 When taking care of patients with ASDs and VSDs in the setting of Eisenmenger syndrome, a practitioner must be aware of the potential for paradoxical emboli during the prothrombotic peripartum period.


Management of ASDs in Pregnancy

ASD closure is recommended postpartum for most patients who present initially during pregnancy.1,3 Although ASDs are tolerated well by most patients, congestive failure and death have been reported.29,30,31 Thus, peripartum management focuses on avoiding vascular resistance changes that increase the degree of the shunt. The majority of patients with ASDs tolerate pregnancy, labor, and delivery without complication (WHO risk class II, with successfully repaired simple ASDs classified as WHO I).3 Neilson and colleagues reported 70 pregnancies in 24 patients with ASDs; all patients had an uncomplicated ante- and intrapartum course.31 During labor, placement of the patient in the lateral recumbent position, avoidance of fluid overload, oxygen administration, and pain relief with epidural anesthesia to avoid increased cardiac output can be helpful.


Ventricular Septal Defects


Clinical Presentation

VSDs may occur as an isolated lesion or in conjunction with other congenital cardiac anomalies, including tetralogy of Fallot, transposition of the great vessels, and coarctation of the aorta. The size of the septal defect is the most important determinant of clinical prognosis during pregnancy. Small defects are tolerated well, whereas larger defects in the high-pressure/high-flow, left-to-right shunt are associated more frequently with congestive heart failure (CHF), arrhythmias, and the development of PH. In addition, a large VSD is often associated with some degree of aortic regurgitation, which further modifies the risk of CHF.


Management of VSDs in Pregnancy

Management considerations for patients with uncomplicated VSDs are similar to those outlined for ASDs. Pregnancy, labor, and delivery are tolerated well by patients with uncomplicated VSD (WHO risk class II, with successfully repaired simple lesions classified as WHO risk I).3 Schaefer and colleagues compiled a series of 141 pregnancies in 56 women with VSD.29 The only two maternal deaths were in women whose VSD was complicated by PH (Eisenmenger syndrome).




Patent Ductus Arteriosus


Clinical Presentation

Although PDA is one of the most common congenital cardiac anomalies, its almost universal detection and closure in the newborn period make it uncommon during pregnancy.33 As with uncomplicated ASD and VSD, most patients are asymptomatic and pregnancy, labor, and delivery are generally well tolerated in patients with PDA (WHO risk class I).3 As with a large VSD, however, the high-pressure/high-flow, left-to-right shunt associated with a large, uncorrected PDA can lead to PH.


Management of PDA in Pregnancy

Management considerations for patients with uncomplicated PDA without PH are similar to those for patients with ASDs.



PH and Eisenmenger Syndrome


Clinical Presentation

PH is defined as a mean pulmonary arterial pressure (PAP) ≥25 mm Hg at rest, diagnosed by right heart catheterization. PH is classified into five broad categories: idiopathic pulmonary arterial hypertension (PAH, WHO Group I); PH due to left heart disease (WHO Group II); PH due to lung disease (WHO Group III); PH due to thromboembolic disease (WHO Group IV); and PH due to unclear or multifactorial etiologies (WHO Group V). PAH carries a high mortality risk during pregnancy, although this risk is decreasing,34 because the pulmonary circulation is not able to adapt to increased cardiac output seen in pregnancy, leading to further increased PAP and RV failure.34 PH is further exacerbated by the prothrombotic state of pregnancy. Maternal mortality is more favorable in women with idiopathic PAH with recent reports of mortality of 17%, decreased to 9% with therapy, and is associated with RV systolic function.1,34,35 Regardless of the etiology, PH carries a guarded prognosis during pregnancy, although the greatest risk may be seen in women with Eisenmenger syndrome.36,37

Eisenmenger syndrome develops when, in the presence of left-to-right shunt, progressive PH leads to shunt reversal or bidirectional shunting as a result of chronically increased pulmonary vascular blood flow with accompanying pulmonary vascular resistance exceeding systemic vascular resistance. Although this syndrome may rarely occur with ASD, VSD, or PDA, the low-pressure/high-flow shunt seen in ASD is far less likely to result in PH and shunt reversal than is the condition of high-pressure/high-flow symptoms seen with VSD and PDA.

In Eisenmenger syndrome, during the antepartum period, decreased systemic vascular resistance in the setting of fixed, high pulmonary resistance increases both the likelihood and the degree of right-to-left shunting. Pulmonary perfusion decreases, with systemic hypotension resulting in hypoxemia with subsequent maternal, then fetal deterioration. The peripartum development of systemic hypotension leads to decreased RV filling pressures; in the concomitant presence of a fixed cardiac output state (eg, PH), such decreased right heart pressures may be insufficient to perfuse the pulmonary arterial bed, leading to a sudden and profound hypoxemia and death.

Maternal mortality in the presence of Eisenmenger syndrome is approximately 28% and has been reported to decrease to 23% with use of targeted therapies for PH.34,38,39 Eisenmenger syndrome associated with VSDs appears to carry a higher mortality risk than that associated with PDA or ASDs. In addition to the previously discussed problems associated with hemorrhage and hypovolemia, thromboembolic phenomena have been associated with up to 43% of all maternal deaths in Eisenmenger syndrome.37 Sudden delayed postpartum death, occurring 4 to 6 weeks after delivery, has also been reported.37,40 Such deaths may involve a
rebound worsening of PH associated with the loss of pregnancy-associated hormones, causing RV failure, arrhythmias, or thromboembolic events.


Management of PH and Eisenmenger Syndrome in Pregnancy

Recent studies suggest that maternal mortality may be lower in patients with mild PH, lower NYHA class, and PH from left HF.41,42 However, the identification of women at lower risk remains a challenge. Thus, the current American College of Cardiology (ACC) and European Society of Cardiology (ESC) guidelines advise against pregnancy in women with PAH and recommend termination for those who become pregnant due to the high mortality associated with continuing pregnancy (WHO risk class IV).3,35

For patients choosing to continue gestation, management centers on decreasing pulmonary vascular resistance, maintaining RV preload, LV afterload, and RV contractility. Thus, factors that increase pulmonary vascular resistance ought to be avoided, and patients should be routinely monitored for occurrence of symptoms, signs of HF, worsening RV function, and increased levels of brain natriuretic peptide. In general, sympathetic agonists (epinephrine and norepinephrine) and conditions resulting in hypoxia or hypercarbia are associated with a poor outcome. Thus, the mainstays of therapy and management for hypoxia continue to be inpatient care in a tertiary care center with experienced clinicians, with continuous administration of oxygen, use of pulmonary vasodilators, avoidance of hypotension and anemia, judicious diuretic use as necessary, and limited use of operative deliveries requiring general anesthesia, as these have been associated with worse outcomes.39,43,44 Inhaled nitric oxide has been used to decrease pulmonary vascular resistance and improved pulmonary blood flow and oxygenation, in conjunction with supplemental oxygen.35 Anticoagulation for Eisenmenger syndrome in pregnancy outside of the usual indications is controversial and not supported by large trials. Evidence suggests early planned delivery around 32 to 34 weeks for women with moderate to severe PH and 35 to 37 weeks for women with mild PH may be reasonable.34,41,42,45 Prophylaxis for endocarditis with antibiotics should be considered as described in Table 28.3.22 Given the elevated mortality risk postpartum, immediately postdelivery patients should be monitored in an intensive care setting, where careful monitoring of hemodynamics can take place.35 Additionally, current recommendations include at least 1 week of in-hospital monitoring for RV failure and PH medication titration.35








Invasive monitoring with an arterial line and central venous catheter is indicated for close monitoring for hypotension and volume status of the decompensating patient. A pulmonary artery catheter will provide useful information among some patients with moderate to severe PH from interatrial shunts.6,44,47 Reference values are provided in Table 28.4. However, among patients with interventricular shunts, catheter placement is associated with a
high rate of complications, including arrhythmias, embolization, and pulmonary artery rupture.34 In instances in which pulmonary artery catheterization may be of benefit, simultaneous cardiovascular imaging may be helpful in catheter placement. If the possibility of right-to-left shunting exists, balloon inflation with carbon dioxide is preferable to that with air in an effort to avoid systemic air embolus associated with the rare occurrence of balloon rupture.








In consideration of catheter placement, it is of note that, during labor, uterine contractions are associated with a decrease in the ratio of pulmonary to systemic blood flow.48,49 Pulmonary artery catheterization and serial arterial blood gas determinations thus theoretically allow the clinician to detect and treat early changes in cardiac output, pulmonary artery pressure, and shunt fraction. Because the primary concern in such patients is the avoidance of hypotension, any attempt at preload reduction (ie, diuresis) must be undertaken with caution, even in the face of initial fluid overload. Some clinicians prefer to manage such patients on the “wet” side (wedge pressure range of 16-18 mm Hg), maintaining a preload margin of safety against unexpected blood loss with an a priori acknowledged risk of pulmonary edema. Because of the increased risk of significant blood loss and hypotension associated with operative delivery, cesarean delivery should be reserved for standard obstetric indications, although many patients have elected to schedule cesarean deliveries in an attempt to avoid overt hemodynamic fluctuations.35 Similarly, midforceps delivery is not warranted to shorten the second stage but should be reserved for obstetric indications only. Likewise, large volume boluses should be avoided, as these can alter the peripartum hemodynamics.

The issue of pulmonary artery catheterization is controversial in Eisenmenger and specifically advised against in patients with this disorder the most recent ACC Scientific Statement.35

If operative delivery is necessary, meticulous attention to hemostasis and surgical technique with an experienced surgical team minimizes the risk of blood loss, hypotension, and death in these patients. Despite expert management, a substantial risk of maternal mortality remains during labor and delivery. Laparoscopic tubal ligation under local anesthesia has also been described in a group of women with various types of cyanotic cardiac disease.50

Anesthesia for patients with PH is controversial. Theoretically, general and single-dose spinal anesthesia, with its accompanying risk of hypotension, should be avoided. Regional techniques for both vaginal (epidural) and cesarean (spinal) delivery have been described and successfully used.34,51

Although any number of inciting events resulting in systemic hypotension in pregnancy may exist, Eisenmenger syndrome most frequently results from hemorrhage or complications of spinal anesthesia.38 Thus, avoidance of systemic hypotension is the principal clinical concern in the intrapartum management of patients with PH of any etiology. This fact is underscored by the longstanding knowledge that the greatest maternal risk occurs in the peripartum period, and most deaths occur between 2 and 9 days’ postpartum.34 The precise pathophysiology of such decompensation is unclear, and it is uncertain what, if any, therapeutic maneuvers prevent or ameliorate such deterioration.



Coarctation of the Aorta


Epidemiology

Coarctation of the aorta accounts for approximately 9% of all congenital cardiac disease.54 More than 400 patients with coarctation have been reported during pregnancy.29,54,55


Clinical Presentation

The most common site of coarctation is the origin of the left subclavian artery. Associated anomalies of the aorta and left heart, including VSDs and PDA, are common, as are intracranial aneurysms in the circle of Willis.55 Coarctation is usually asymptomatic. Its presence is suggested by hypertension confined to the upper extremities, although Goodwin cites data suggesting a generalized increase in peripheral resistance throughout the body.55 Resting cardiac output may be increased, but increased left atrial pressure with exercise suggests occult LV dysfunction. Aneurysms may also develop below the coarctation, or involve the intercostal arteries, and may lead to rupture. In addition, ruptures without prior aneurysm formation have been reported.54,55


Management of Coarctation of the Aorta in Pregnancy

Patients with coarctation of the aorta uncomplicated by aneurysmal dilation or associated cardiac lesions entering pregnancy as NYHA class I or II have a good prognosis and a minimal risk of complications or death.56,57 Even if uncorrected, uncomplicated coarctation carries with it a risk of maternal mortality of only 3% to 4%.56 In the presence of aortic or intervertebral aneurysm, known aneurysm of the circle of Willis, or associated cardiac lesions, however, the risk of death may approach 15%; therefore, pregnancy termination must be strongly considered.44 Women with repaired coarctation often tolerate pregnancy well and have thus been classified as WHO risk class II to III (Table 28.2).3 Women with coarctation should have close monitoring of blood pressure, and hypertension should be avoided, especially in cases of recoarctation. Percutaneous intervention for recoarctation is feasible but should be avoided, if possible, during pregnancy.3

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Jun 19, 2022 | Posted by in OBSTETRICS | Comments Off on Cardiac Diseases in Pregnancy
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