26: Cardiovascular disease

Cardiovascular disease

Megan L. Jones1 and Michael R. Foley2

1The University of Ohio Wexner Medical Center, Columbus, OH, USA

2Banner University Medical Center Phoenix, Obstetrics and Gynecology, University of Arizona College of Medicine Phoenix, Phoenix, AZ, USA


Physiologic changes of pregnancy

The physiologic changes of pregnancy create a state of high flow and low resistance. Beginning in the first trimester, cardiac output rises due to an increased stroke volume, and the addition of an increased heart rate by the second trimester intensifies this value [1]. By mid‐second trimester cardiac output has increased by 25–50%, and this remains stable throughout the duration of pregnancy [2]. Additionally, preload is increased due to a 40–50% increase in blood volume [1]. Systemic vascular resistance (SVR) falls by six weeks gestation, which accounts for the fall in systolic and diastolic blood pressure by 5 and 10 mmHg, respectively, throughout the first half of pregnancy. This subsequently rises to pre‐pregnant values in the third trimester [1, 2].

Normal physical exam findings in pregnant women reflect the state of high flow and low resistance. Distended neck veins, prominent left and right ventricular impulses, systolic ejection murmur, peripheral edema, and trace pulmonary edema can be normal. However, given the similarity of normal findings with heart failure, evaluation of a patient with cardiac disease in pregnancy can be complicated [3].

The hemodynamic changes in pregnancy will also be reflected in imaging and electrical studies. Frontal axis leads in an electrocardiogram (ECG) will show mild left axis deviation (15–20%), and nonspecific ST segment and T wave abnormalities are seen in 4–14% of pregnancies [4, 5]. During echocardiography, pregnant women should be positioned in the left lateral decubitus to avoid inferior vena cava (IVC) compression by the gravid uterus, which can alter measurements. In general, eccentric hypertrophy is seen with a stable increase in the ratio of wall thickness to ventricular radius. Left ventricular systolic and diastolic function is relatively stable, but a slight increase in ejection fraction (EF) can be observed. Physiologic regurgitation is common due to the increase in blood volume and chamber dimensions. Asymptomatic pericardial effusions have been observed in up to 40% of pregnant women, especially primigravidas and those with more than 12 kg weight gain [6].

During labor, the effects of pain, sympathetic tone, and uterine contractions further increase cardiac output, SVR, and blood pressure. Relief of IVC compression and auto‐transfusion following delivery promotes a further increase in cardiac output. The hemodynamic changes of pregnancy will typically resolve by two weeks postpartum but can take up to six weeks in some patients [1].

Epidemiology of cardiac disease

The prevalence of cardiac disease among reproductive age women in the United States is 1%, and pregnancy can create significant morbidity and mortality for these women. With regards to pregnancy, cardiac disease is identified in 0.1% of those in developed countries and 0.6% in developing countries [7]. Cardiac disease can be divided into acquired and congenital lesions, and the prevalence of each of these categories varies among developing versus developed countries. Acquired valvular lesions from the sequelae of rheumatic heart disease account for 60–80% of cardiac disease in pregnancy in developing countries. Whereas this held true for developed countries also until the last decade, there has been a shift toward a higher prevalence of congenital cardiac disease in pregnancy in developed regions. This is attributed to advancements in technology and success of reparative surgery, which has allowed more women to live to reproductive ages [8]. Despite this shift, acquired cardiac disease is still rising in developed regions due to prolongation of pregnancy and the increased prevalence of hypertension, diabetes, and hypercholesterolemia in women of advanced maternal age, which places further risk for the onset of cardiac disease during pregnancy [9]. Regardless of etiology, cardiac disease is collectively the most common indirect cause of maternal death, contributing to 9% mortality in developing countries, 36% mortality in developed countries, and 18% of ICU admissions across the United States [7, 10]. Therefore, thoughtful assessment, counseling, and management must be employed for optimal care of these pregnant women.

Risk assessment models for pregnant women with cardiac disease

The New York Heart Association (NYHA) created a classification system in 1994 to categorize functional status related to cardiac disease in a general population. Class I describes those with cardiac disease who have no limitations of physical activity and minimal symptoms with ordinary activity. Class II describes those with slight limitation in activity and significant symptoms with ordinary activity. Class III describes those with marked limitation in activity and significant symptoms with less than ordinary activity. Class IV describes those with discomfort performing any activity and significant symptoms at rest [11].

Risk assessment of cardiac disease in pregnancy is a priority for the obstetrician. The NYHA functional classification remains useful to assess and describe women who become pregnant; however, risk assessment models specific to pregnant women with cardiac disease have been proposed to aid in predicting the risk of maternal cardiac events given the condition, maternal history, and current functional status.

The risk for complications associated with pregnancy in women with heart disease (CARPREG risk score) was created from a retrospective evaluation of risks and predictors of cardiac complications in pregnant women with cardiac disease [12].

Four predictors were identified, and each was given 1 point:

  • Poor functional class (NYHA class III or IV) or cyanosis.
  • Previous cardiovascular event including heart failure, transient ischemic attack, stroke, or arrhythmia.
  • Left heart obstruction (mitral valve area <2 cm2, aortic valve area <1.5 cm2, or peak left ventricular (LV) outflow gradient >30 mmHg).
  • Left ventricular systolic dysfunction (EF <40%).

Subsequently, these findings were applied prospectively to a group of 562 women with 617 pregnancies who had congenital or acquired cardiac disease. The overall rate of cardiac events (pulmonary edema, arrhythmia requiring treatment, stroke, cardiac arrest, or death) was 13%, and about half of these occurred in the antepartum period. The rate of events predicted by the risk score of 0, 1, or >2 points was very congruent with the rates observed in the retrospective analysis: 0 points (4% versus 5%); 1 point (26% versus 27%); >2 points (62% versus 75%) [13]. Furthermore, specific analysis of the CARPREG risk score in 53 women with congenital cardiac disease in 90 pregnancies elicited an overall rate of cardiac events to be 25%. Congruency with no statistical difference was observed among the actual incidence of events and rates predicted by the CARPREG risk score [14] (Table 26.1).

Table 26.1 CARPREG risk prediction score for a cardiac event during pregnancy

Risk predictors Points
Poor functional class (NYHA class III or IV) or cyanosis 1
Previous cardiovascular event: heart failure, transient ischemic attack, stroke, or arrhythmia 1
Left heart obstruction:
Mitral valve area <2 cm2, aortic valve area <1.5 cm2, or peak left ventricular outflow gradient >30 mmHg
Left ventricular systolic dysfunction (ejection fraction <40%) 1

Score: 0 points = 5% risk; 1 = 27% risk; ≥2 = 75% risk.

The risk score for cardiac complications during completed pregnancies in women with congenital heart disease (Zwangerschap bij vrouwen met een Aangeboren HARtAfwijking‐II; ZAHARA risk score) was created from a retrospective cohort study of 714 women with congenital cardiac disease in 1302 pregnancies [15]. This risk score has not been validated in further studies, however (Table 26.2).

Table 26.2 ZAHARA risk prediction score for a cardiac event during pregnancy

Risk predictors Points
Mechanical heart valve 4.25
Severe left heart obstruction (mean pressure gradient >50 mmHg or aortic valve area <1.0 cm2) 2.5
History or arrhythmia 1.5
History of cardiac medication use before pregnancy 1.5
History of cyanotic heart disease – corrected and uncorrected 1
Moderate‐to‐severe pulmonary or systemic atrioventricular valve regurgitation 0.75
Symptomatic heart failure before pregnancy (NYHA class ≥2) 0.75

Score: 0–0.5 points = 3% risk; 0.51–1.5 = 8% risk; 1.51–2.5 = 18% risk; 2.51–3.5 = 43% risk; ≥3.51 = 70% risk.

The following factors are scored from a weighted system:

  • Mechanical heart valve (4.25 points).
  • Severe left heart obstruction (mean pressure gradient >50 mmHg or aortic valve area <1.0 cm2) (2.5 points).
  • History of arrhythmia (1.5 points).
  • History of cardiac medication use before pregnancy (1.5 points).
  • History of cyanotic heart disease – corrected and uncorrected (1.0 points).
  • Moderate‐to‐severe pulmonary or systemic atrioventricular valve regurgitation (0.75 points).
  • Symptomatic heart failure before pregnancy (NYHA class >2) (0.75 points).

The summation of an individual score is used to predict the risk of a cardiac event that is divided into five categories: 0–0.5 points (3%); 0.51–1.5 points (8%); 1.51–2.5 points (18%); 2.51–3.5% (43%); >3.51 (70%) [15].

The World Health Organization (WHO) created a classification system that separates cardiac disease into four categories, and specific risks are assigned for each category. A large prospective study from the European Registry on Pregnancy and Heart Disease applied the WHO classification system to 1321 pregnancies, and this model showed statistical significance in comparing maternal morbidity among classes. Although statistical significance was not observed among classes for maternal mortality, risk prediction was still considered excellent [16]. The European Society of Cardiology (ESC) adopted this classification system into their guidelines for management of cardiac disease in pregnancy, which were published in 2011 [17].

Class I includes conditions associated with no detectable increased risk of maternal mortality and no/mild increase in morbidity. Cardiology follow‐up should occur one or two times during pregnancy.

  • Uncomplicated, small patent ductus arteriosus (PDA), mild pulmonic stenosis, or mitral valve prolapse.
  • Successfully repaired simple lesions (atrial septal defect or ventricular septal defect (ASD/VSD), PDA, or anomalous pulmonary venous drainage).
  • Isolated atrial or ventricular ectopic beats.

Class II includes conditions associated with a small increased risk of maternal mortality or a moderate increase in morbidity. Cardiology follow‐up should occur every trimester.

  • Unrepaired ASD/VSD.
  • Repaired tetralogy of Fallot (TOF) or coarctation.
  • Arrhythmias.
  • Mild LV dysfunction.
  • Hypertrophic cardiomyopathy (HCM).
  • Native or bioprosthetic valvular heart disease not considered WHO I or IV.
  • Marfan syndrome with aortic diameter <40 mm without aortic dissection.
  • Bicuspid aortic valve with ascending aortic diameter <45 mm.

Class III includes conditions associated with significant increased risk of maternal mortality or severe morbidity. Cardiology follow‐up should occur every four to eight weeks.

  • Mechanical valve.
  • Systemic right ventricle.
  • Fontan circulation.
  • Unrepaired cyanotic heart disease.
  • Complex congenital cardiac disease.
  • Bicuspid aortic valve with ascending aortic diameter 45–50 mm.
  • Marfan syndrome with aortic root diameter 40–45 mm.

Class IV includes conditions associated with extremely high risk of maternal mortality or severe morbidity, for which pregnancy is contra‐indicated. If pregnancy occurs and termination is declined, then cardiology follow‐up every four to eight weeks should occur.

  • Severe mitral stenosis or symptomatic severe aortic stenosis.
  • Bicuspid aortic valve with ascending aortic diameter >50 mm.
  • Marfan syndrome with aortic root diameter >45 mm.
  • Severe systemic ventricular systolic dysfunction (LV EF <30% or NYHA class III–IV).
  • Native severe coarctation.
  • Significant pulmonary arterial hypertension (pulmonary artery systolic pressure >25 mmHg at rest or >30 mmHg with exercise).

During comparison of these risk assessment models, the WHO classification system has proven superiority in risk prediction. In a prospective study of 203 women with congenital cardiac disease in 213 pregnancies, CARPREG and ZAHARA risk scores were calculated for each pregnancy along with identification of WHO classification. Each risk assessment model performed sufficiently for risk estimation, but the WHO classification had the best performance [18]. Similarly, a retrospective study applied each of the three assessment models to 190 women with congenital cardiac disease in 268 pregnancies from 1985 to 2011 and found excellent performance of each model with superiority of the WHO classification system in discrimination and calibration [19].

Acquired cardiac disease

Clinical questions and critical review of the literature

  1. What are the common etiologies for acquired valvular lesions in pregnant women?

Search Strategy: MEDLINE: pregnancy AND heart valve AND maternal.

Mitral and aortic diseases are common acquired lesions, which can be stenotic or regurgitant, in contrast to pulmonic disease, which is largely congenital. Mitral stenosis is the most common valvular lesion in pregnancy, with a majority of cases attributed to rheumatic disease, especially in developing countries [8]. These lesions can go unnoticed throughout a lifetime, but the increased blood volume and hemodynamic changes of pregnancy can initiate new symptoms and exacerbate the condition [6]. Rheumatic disease can also cause mitral regurgitation, but the most common etiology of this lesion in reproductive age women is mitral valve prolapse. Others include infective endocarditis (IE) and functional regurgitation from left ventricle dilation during pregnancy [20]. Aortic stenosis and regurgitation are most frequently caused by congenital bicuspid aortic valve, but they have also been associated with IE and rheumatic disease. Among all cases of mitral lesions caused by rheumatic disease, 5% will also have aortic lesions. Aortic regurgitation can be acquired from connective tissue disorders such as Marfan syndrome as well [21].

  1. 2. What should pre‐conception counseling entail for women with cardiac disease?
  2. Search Strategy: MEDLINE: pregnancy AND heart disease AND maternal AND counseling.

Young girls with cardiac disease should be counseled regarding effective contraception to avoid the morbidity and mortality associated with pregnancy. Once a woman is contemplating pregnancy, further discussion should include the risks of maternal mortality and cardiac complications during pregnancy along with obstetric complications, risks of fetal and neonatal morbidity and mortality, risks of inheritance of cardiac disease to the offspring, and the anticipated course of antepartum surveillance [22]. Each patient will have a unique risk profile based upon the type of lesion, severity, and current functional status. This lends to the importance of a detailed history and physical exam, with attention focused on functional status, signs and symptoms of cardiac dysfunction (dyspnea, orthopnea, and peripheral edema), prior cardiac events, and prior surgery. The risk assessment models discussed previously can aid in providing accurate predictions of expected complications in pregnancy.

Additionally, structural and functional assessment of the heart should be performed with an echocardiogram prior to pregnancy before hemodynamic changes alter the study. Specifically, valve structure and function, lesion severity, ventricular function, and pulmonary artery systolic pressure should be evaluated. Cardiac surgery during pregnancy should be avoided; therefore, women should perform any necessary procedure or surgery prior to pregnancy if indications are present. These interventions can also help improve fertility, tolerance of the physiologic changes of pregnancy, and maternal and fetal morbidity and mortality [20].

  1. 3. What is the appropriate antepartum management for a woman with an acquired cardiac lesion?
  2. Search Strategy: MEDLINE: pregnancy AND heart valve AND maternal.

Women achieving pregnancy with acquired cardiac disease or valvular lesions should have ongoing evaluation and care by an obstetrician trained and skilled for managing these conditions, a cardiologist, and anesthesiology consultation to confirm plans and recommendations for labor and delivery management. Typically, prenatal evaluation occurs every four weeks until 28 weeks gestation, then every two weeks until 36 weeks gestation and weekly thereafter. Cardiology evaluation every four to eight weeks is recommended with echocardiogram to assess cardiac structure and function. If a woman has severe disease or is symptomatic, more frequent assessment is necessary [2].

Evaluation of a symptomatic patient with cardiac disease can be challenging in pregnancy given the similarity of normal physiologic symptoms of pregnancy, such as fatigue, dyspnea, and peripheral edema. Onset of symptoms due to cardiac pathology tends to be highest in the second half of pregnancy and peripartum period when cardiac output and blood volume are highest. Echocardiography is imperative in the evaluation to assess valvular and ventricular function for comparison with prior studies [7]. Most lesions are known ahead of time, but echocardiography can distinguish a new cardiac diagnosis if pregnancy physiology has revealed an unrecognized lesion [20]. Chest X‐ray and ECG are reasonable alternatives when echocardiogram is unavailable, but these are also optimal studies to use in conjunction with echocardiogram for assessment of lung fields and chamber morphology. If cardiac assessment is reassuring, then other etiologies of infection, pulmonary embolus, or asthma exacerbation should be evaluated [7].

If pre‐conception genetic counseling was not performed, then arranging this early in pregnancy is ideal. Fetal echocardiography from 19 to 22 weeks gestation should be offered to a pregnant woman when either parent is affected. Nuchal fold thickness measurement in the first trimester has a 99% negative predictive value for ruling out cardiac disease with a reassuring value [23]. Both studies can help distinguish those fetuses at risk for inherited cardiac disease.

  1. 4. What are the maternal and obstetric risks associated with valvular lesions in pregnancy?
  2. Search Strategy: MEDLINE: pregnancy AND valve disease AND maternal AND risks.

Acquired valvular lesions can create a myriad of maternal and obstetric complications in pregnancy, which can be related to the type and severity of lesion in addition to the alteration in hemodynamics from the physiologic changes of pregnancy. Risk assessment models can help predict the onset of these complications, but prompt assessment and treatment must be employed.

Mitral stenosis is graded on the measurement of the valve diameter, which is obtained from echocardiography. A normal mitral valve diameter is 4–6 cm2, and abnormalities are diagnosed with the following values: >1.5 cm2 (mild disease), 1–1.49 cm2 (moderate disease), and <1.0 cm2 (severe disease) [24]. Mild disease is typically associated with NYHA class I–II (symptoms with strenuous activity). Moderate disease is most frequently associated with NYHA class III (symptoms with ordinary or less than ordinary activity), and severe disease is associated with NYHA class IV (symptoms at rest) [7].

Generally, stenotic lesions are poorly tolerated in pregnancy due to the increased volume and intensification of gradients across valves. Multiple small studies have shown that a decreased mitral valve area and more advanced functional class before pregnancy are strongly associated with decompensation and maternal complications [2527]. Mild disease rarely precipitates symptoms, but those with moderate or severe disease (mitral valve area <1.5 cm2) are at a significantly increased risk for arrhythmias, pulmonary edema, and heart failure, which can be progressive and typically onset in the second half of pregnancy. If an arrhythmia onsets, then the additional risk of a thromboembolic event arises [26, 27]. Overall mortality for mitral stenosis is 1–3% in developed nations, but developing countries can observe maternal mortality up to 30% [20]. Therefore, avoidance of pregnancy or treatment prior to pregnancy should occur in women with moderate to severe disease.

Similarly, maternal complications linked to aortic stenosis depend on the severity of the lesion and presence of symptoms. Those with mild to moderate disease without symptoms can generally tolerate pregnancy well, and the rate of complications is extremely low [28, 30]. Severe disease is characterized by an aortic diameter <1 cm2 or gradient >50 mmHg, and this carries significant risk for heart failure (10%) and arrhythmias (3–25%) [20, 29]. Mortality is actually rare given the escalation of appropriate management [26, 28, 29]. Careful attention to symptoms in women with severe aortic stenosis guides management. Even in women with critical measurements that remain asymptomatic, have a normal blood pressure response to exercise testing, no evidence of severe LV hypertrophy or a progressive lesion, pregnancy can be tolerated well, and pre‐pregnant treatment might not be necessary. However, if any of these factors are identified, then pregnancy should be avoided until proper treatment is employed [2931].

Regurgitant lesions are often better tolerated in pregnancy than stenotic lesions. The physiologic changes of pregnancy create a decrease in SVR and increased cardiac output, which aid in propagating blood flow in a forward direction [6, 20]. Maternal cardiac risk associated with aortic and mitral regurgitation is dependent upon symptoms, regurgitation severity, and LV function. Increased symptoms and suboptimal LV function can precipitate heart failure in pregnancy [7, 32]. Arrhythmias are of more concern in an asymptomatic woman with preserved LV function, and progressive worsening of regurgitation is always a risk in any woman with baseline disease [15, 33]. If severe symptoms or LV dysfunction are present, then valve repair or replacement prior to pregnancy is warranted. Otherwise, pregnancy can be advised with close observation and risk counseling [20].

  1. 5. When is intervention necessary for valvular lesions in pregnancy? What treatment options are available?
  2. Search Strategy: MEDLINE: pregnancy AND valve disease AND treatment.

Proper assessment of valvular function prior to pregnancy is vital to properly plan for treatment interventions necessary before conception occurs. If indicated, procedures performed prior to pregnancy can optimize functional status, decrease symptoms, and help avoid obstetrical complications. When lesions are mild and symptoms are minimal, medical management and intensive follow‐up throughout pregnancy can be maintained. There are no randomized controlled trials to evaluate the efficacy of interventions for cardiac disease in pregnancy. Most recommendations are made from observational studies, which have limitations and selection bias to account for [8].

When symptoms of volume overload present in women with stenotic lesions, primary goals are to reduce activity, volume, and cardiac workload. Pulmonary and peripheral edema, pulmonary hypertension, dyspnea and fatigue from an inadequate cardiac output due to cardiac dysfunction, and arrhythmias from dilated chambers with blood flow stasis are signs and symptoms of significant decompensation. These women should be counseled to minimize activity, which exacerbates symptoms, and to rest. Oral diuretics, such as thiazides and furosemide, may be initiated along with β1‐specific receptor antagonists. If a woman develops atrial fibrillation, anticoagulation, along with a β‐receptor antagonist or non‐dihydropyridine calcium channel antagonist for rate control, should commence [21, 34]. Digoxin can be used in refractory cases [7, 35]. If echocardiography shows significantly dilated chambers (left atrium >40 ml m−2), low cardiac output or a woman has symptoms of congestive heart failure, then anticoagulation should also be considered [21, 34].

If women with moderate to severe mitral stenosis (mitral valve area <1.2 cm2) are considered NYHA class III–IV, perform pathologic exercise tests or have pulmonary arterial pressures >50 mmHg, then intervention prior to pregnancy is recommended. These women have a 60% risk for deterioration in pregnancy, and treatment helps optimize functional status and obstetric outcomes [27]. If not performed prior to pregnancy, then treatment during pregnancy is reserved for women meeting the same criteria or having progressive disease despite medical therapy optimization [7, 21, 34].

Percutaneous balloon mitral commissurotomy is the preferred treatment option if echocardiography confirms a mobile, non‐calcified valve and no left atrial thrombus, which are contra‐indications to the procedure [6]. Fluoroscopy is necessary for the technique, so optimal timing for treatment is beyond 14 weeks, abdominal shielding is recommended, and using the Inoue balloon catheter can facilitate a shorter procedure time. All these factors help minimize radiation effects to the fetus. Total fetal radiation exposure <5 rad is optimal for an entire pregnancy, and approximately 0.2 rad is administered with abdominal shielding and an average fluoroscopy time of 16 minutes [7, 21, 34, 36]. There has been tremendous success with balloon commissurotomy performed in pregnancy. Mitral valve area has been shown to increase from 1 to 2 cm2, which is similar to the efficacy seen in non‐pregnant patients [3740]. Additionally, functional status, pulmonary artery pressure, and pressure gradient across the valve have shown improvement [7, 38, 4143].

The fewest complications are observed with balloon commissurotomy. Maternal mortality is rare, with rates as low as <1%. However, minor risks of tamponade, hemorrhage, transient atrial fibrillation, worsening mitral regurgitation, and pulmonary edema have been reported [37, 4143]. Fetal effects have been favorable [44, 45], but most studies report increased risks of stillbirth, growth restriction, and preterm birth, despite treatment [27, 46, 47]. This might be related to the underlying disease or late timing of intervention that prevents the fetus from gaining all the physiologic benefit in such a short time. Nevertheless, offspring have shown normal growth and development following the procedure for up to seven years [44, 45, 4852]. In developing countries or when percutaneous procedures are unavailable, closed mitral commissurotomy is preferred, with a slightly higher maternal mortality (2.5%) [7]. Fetal mortality for percutaneous and closed procedures remains <10%, but this rises to 10–30% when open‐heart surgery is performed for commissurotomy or valve replacement. These procedures should be reserved for refractory cases when a mother’s life is threatened [7, 21, 34, 53, 54].

In severe aortic stenosis (aortic valve area <1 cm2), an additional factor of symptoms, significant LV dysfunction or hypertrophy, or progressive stenosis will merit the need for intervention prior to conception to avoid the high probability of deterioration and to optimize maternal, fetal, and obstetric outcomes. Additionally, valve gradient >50 mmHg should prompt pre‐conception treatment [21, 34]. Otherwise, pregnancy is usually tolerated well in women with severe aortic stenosis without any additional complications [28, 34]. If pregnancy commences prior to intervention, rest and medical management should be maximized. If no improvement is observed, nonetheless, balloon valvuloplasty can be performed in non‐calcified valves with minimal regurgitation [57]. The same principles apply to timing of the procedure and precautions taken for fetal radiation exposure as for mitral valve balloon commissurotomy, but there is little data that reports efficacy and maternal and fetal outcomes following this procedure [7, 21, 55, 56]. If valvuloplasty is unable to be performed, then early delivery of the fetus followed by valve replacement should be executed due to the 30% fetal mortality risk associated with valve replacement surgery [2, 57].

Regurgitant lesions are better tolerated than stenotic lesions in pregnant women; therefore, thresholds for intervention are much higher. Volume overload can be managed with oral diuretics, and symptoms can be minimized with rest and limitations of activity. If severe regurgitation stimulates compromised LV function or significant symptoms of heart failure (NYHA class III–IV) refractory to medical management, then surgery is an option. Valve repair is preferred over replacement to avoid the risks of thrombosis and anticoagulation [20, 34]. Fetal mortality can reach 30% with open surgery and cardiopulmonary bypass, so the risks and benefits of early delivery prior to surgery should be discussed [21, 34].

  1. 6. What are the key principles in managing women with artificial valves?
  2. Search Strategy: MEDLINE: pregnancy AND mechanical valve.

When artificial valves function appropriately, pregnancy can be hemodynamically tolerated well, but there is a baseline risk of 1–4% maternal mortality. Valve thromboses can increase this mortality risk to 65%, and the type of valve material and anticoagulation regimen used play a significant role in predicting thrombosis risk. Compared to donor and bioprosthetic valves, mechanical valves are more frequently used due to their durability and longevity, but anticoagulation must be used concomitantly due to the high propensity of thrombosis. Risk of hemorrhage, obstetric complications, and fetal teratogenicity in addition to valve thrombosis and the potential sequelae raise concern for pregnant women [2].

There are no randomized controlled trials to evaluate methods of anticoagulation, but smaller cohort studies and systematic reviews provide data for recommendations. Most recent reports suggest that warfarin used throughout the pregnancy elicits a 2% risk for thrombosis and also maternal mortality compared to substitution of unfractionated heparin (UFH) during the first trimester (6–12 weeks gestation), which carries a 10% risk for thrombosis and 4% risk for maternal mortality [58]. UFH used exclusively throughout the pregnancy conveys a 33% risk for thrombosis and 15% risk for maternal mortality [59]. Undoubtedly, warfarin seems to be the ideal anticoagulant; however, risks of embryopathy limit its use in the first trimester. Warfarin crosses the placenta and can create effects such as a depressed nasal bridge, bone stippling, congenital cardiac disease, growth restriction, developmental delay, and seizures, which describe the fetal warfarin syndrome. When doses <5 mg are used, the risks of embryopathy remain similar to that of the general population for congenital anomalies (2.5%); conversely, doses >5 mg can increase this risk up to 10% [5964]. Use beyond the first trimester still carries a risk of central nervous system abnormalities and fetal hemorrhage given the immature liver enzymes and low levels of vitamin K dependent clotting factors in the fetus [2]. At delivery, fetal intracranial bleeding is a risk if a mother has a vaginal delivery while concurrently taking warfarin; therefore, transition to UFH nearing delivery is ideal or cesarean is necessary [2, 63].

If doses of warfarin remain <5 mg, then continuation throughout pregnancy is recommended. Alternatively, intravenous (IV) or IM UFH can be used 6–12 weeks gestation to avoid the risks of embryopathy if warfarin dose rises above 5 mg, but the increased risk of thrombosis must be accepted. UFH does not cross the placenta, but the risks of thrombocytopenia and osteoporosis do exist [65, 66]. Although low molecular weight heparin (LMWH) has fewer side effects and seems more convenient for home administration, use in pregnancy with mechanical valves is controversial due to the lack of supporting data regarding frequency of dosing, timing and goals of anti‐Xa levels, and outcomes compared to warfarin and heparin. Small studies have reported thrombosis risks of 4% and 9% when LMWH was used only in the first trimester and throughout the pregnancy, respectively [58, 6769]. Therapeutic dosing should begin at 1 mg kg−1 twice daily, and multiple studies have shown that fixed dosing compared to dose adjustments throughout pregnancy has a significantly higher risk for thrombosis [66, 70]. Increased renal clearance and volume of distribution as pregnancy progresses necessitates continued titration to a peak goal of 0.8–1.2 U ml−1 (four to six hours following dose). Some suggest that even three times daily dosing might be advantageous [38]. Currently, there is no official approval for LMWH use in pregnant women with mechanical heart valves, and it should be used judiciously.

Anticoagulation certainly helps protect against the risk for thrombosis in mechanical valves, but any regimen still carries obstetric and neonatal risks. Women must be counseled regarding the risk for miscarriage and retro‐placental hemorrhage, which can precipitate preterm birth and fetal death [2, 59, 6163, 70]. After appropriate counseling, a regimen must be devised for monitoring goals and frequency. The American College of Cardiology (ACC), American Heart Association (AHA), and ESC suggest warfarin be continued until pregnancy is achieved. Either continuing warfarin or transitioning to UFH from 6 to 12 weeks gestation is appropriate, with resumption of warfarin in the second and third trimesters. The AHA and ESC endorse the use of LMWH from 6 to 12 weeks gestation if peak anti‐Xa level can be maintained 0.7–1.2 U ml−1. International normalized ratio (INR) and activated partial thromboplastin time (aPTT) must be kept twice the control level, and weekly monitoring is suggested for any regimen [34, 71].

  1. 7. What are the fetal and neonatal risks associated with valvular lesions in pregnancy?
  2. Search Strategy: MEDLINE: pregnancy AND valve disease AND maternal AND risks.

Among all the acquired cardiac and valvular lesions, common risks of fetal growth restriction, stillbirth, and preterm birth are observed and related to the severity of the disease and cardiac complications that arise, such as heart failure and arrhythmias. Women with stenotic lesions who are symptomatic or who have moderate to severe disease have a 5–25% risk for fetal growth restriction, 1–3% risk for stillbirth, and 30% risk for preterm birth [27, 29, 46]. Regurgitant lesions are better tolerated in pregnancy, but the overall risk for fetal growth restriction, stillbirth, and preterm birth are still slightly increased [13]. Beyond the baseline risks associated with decompensation of cardiac disease in pregnancy, medical therapy adds a trivial amount of increased risk to the fetus. Surgery can increase fetal mortality risk up to 30% depending on the type performed; percutaneous procedures are preferred over open heart surgery for valve replacement [2, 57].

  1. 8. During labor and delivery, what is the preferred mode of delivery, anesthesia method, and intrapartum monitoring for women with acquired or valvular lesions?
  2. Search Strategy: MEDLINE: pregnancy AND valve disease AND delivery.

In general, women with acquired and valvular lesions should attempt a vaginal delivery with regional anesthesia whenever possible. Vaginal delivery has less risk of bleeding, infection, and venous thromboembolism, which can significantly impact a woman with cardiac disease [72]. There is limited data comparing outcomes following vaginal and cesarean delivery, but small studies have reported vaginal delivery success in women that even have moderate to severe disease. Those women with mild disease or repaired valvular lesions should undergo management similar to normal pregnant women. In most women with cardiac disease, spontaneous labor is preferred, and decision for induction of labor should take into account a woman’s Bishop score, fetal status, maternal functional status, and timing of anticoagulation [1, 21, 30].

Short and pain‐free labor is ideal to avoid hemodynamic changes associated with pain, contractions, and pushing. In women with stenotic lesions, caution with regional anesthesia to avoid a substantial drop in SVR and sufficient IV fluids to maintain adequate preload is urged. Volume should be carefully balanced in women with regurgitant lesions to avoid pulmonary edema and volume overload. Continuous monitoring of oxygen saturation, blood pressure, ECG, and arterial pressure in isolated cases are warranted during the labor and delivery course along with fetal monitoring that will display a direct reflection of placental perfusion and oxygenation. An assisted second stage is recommended to minimize pushing effort and expedite delivery. In isolated situations of severe stenosis with significant symptoms or pulmonary hypertension, it is reasonable to perform a cesarean under general anesthesia. Otherwise, cesarean is reserved for obstetric indications [1, 21, 30]. Delivery of all high‐risk women with moderate to severe disease or significant symptoms should be performed in a tertiary care center with collaborative management by skilled obstetricians, cardiologists, and anesthesiologists [71, 73].

  1. 9. Is antibiotic prophylaxis necessary for pregnant women with cardiac disease?
  2. Search Strategy: MEDLINE: pregnancy AND heart disease AND endocarditis.

IE in pregnancy is extremely rare with an incidence of 1/100 000 pregnancies (0.006%) [74], and there is just a slight increase for women with valvular or congenital cardiac disease [75]. Drug addiction, prosthetic valves, prior endocarditis, and untreated cyanotic heart disease are factors that place patients in the highest risk categories, but recommendations for antibiotic prophylaxis during pregnancy and invasive procedures for even the highest risk patients have evolved since early 2000 [76].

Previous recommendations for antibiotic prophylaxis were developed from a multitude of case reports and animal models that revealed transient bacteremia following invasive procedures. Nevertheless, the principle that antibiotic prophylaxis should decrease bacteremia, attachment of bacteria to the endocardium and subsequent IE has only been proven in animal models, and efficacy in humans is controversial [7779]. Very few studies have correlated IE with invasive procedures, such as dental, which provokes the theory that the risk for IE is more likely to occur from cumulative low‐grade bacteremia from daily activities, such as tooth‐brushing or flossing, than from isolated high‐grade bacteremia following dental procedures [80]. Furthermore, antibiotic use has been shown to be cost‐ineffective, to intensify the emergence of resistant microorganisms, and to transmit a risk of anaphylaxis [7779]. Beginning in 2002, restriction of antibiotic prophylaxis to the highest risk patients during dental procedures was propagated by the AHA, ACC, ESC, and National Institute for Health and Care Excellence (NICE), and no increase in IE has been observed [8184]. Pregnant women with cardiac disease do not require antibiotic prophylaxis during labor and delivery, regardless of vaginal or cesarean mode. If these women have a high‐risk characteristic, then the ESC supports considering prophylaxis during dental procedures [76, 85].

  1. 10. What care should be employed in the postpartum period for women with valvular lesions?
  2. Search Strategy: MEDLINE: pregnancy AND valve disease AND delivery.

The largest hemodynamic changes and fluid shifts occur within 12–24 hours following delivery, so hemodynamic monitoring should persist for 24 hours. Fluid balance and monitoring for heart failure symptoms are important in this immediate postpartum time period. Following delivery, IV oxytocin infusion should ensue to prevent postpartum hemorrhage, and it has minimal effect on SVR. If additional uterotonics are necessary, then prostaglandin F analogues can be used. Misoprostol is supported as well, but there is a small increased risk of coronary vasospasm and arrhythmia. Methylergonovine is contra‐indicated due to the 10% risk for vasoconstriction and hypertension [21, 86, 87]. Breastfeeding is recommended unless women are extremely symptomatic and critically ill.

Graded recommendations for the management of acquired valvular cardiac disease in pregnancy [176] :

  • Prepregnancy counseling and risk assessment is indicated in all women with known or suspected congenital or acquired cardiovascular disease (I‐C).
  • High‐risk women with cardiac disease should be cared for by a multidisciplinary team involving an obstetrician, cardiologist, and anesthesiologist, and delivery should occur at a specialized center (I‐C).
  • Cardiology follow‐up should be outlined at the beginning of pregnancy; typical schedules range from twice to monthly (I‐C).
  • Echocardiography should be performed in any pregnant woman with new or unexplained cardiovascular signs or symptoms (I‐C).
  • Pregnant women with mechanical valves should utilize anticoagulation throughout pregnancy (I‐C).
  • Vaginal delivery with regional anesthesia is recommended as first choice for most women with cardiac disease (I‐C).
  • Management to prevent IE in pregnancy is the same as that for non‐pregnant patients (I‐C).
  • In women undergoing a vaginal delivery, regional anesthesia and an elective operative delivery should be considered (IIa‐C).
  • Cesarean delivery should be considered for women with severe aortic stenosis, continued oral anticoagulation at time of delivery or severe symptomatic heart failure (IIa‐C).
  • If gestational age is >28 weeks, then delivery prior to cardiac surgery should be considered (IIa‐C).
  • Valvular or reparative cardiac surgery may be considered when conservative therapy has failed, a mother’s life is threatened, and percutaneous treatment is not an option (IIb‐C).
  • Antibiotic therapy for the prevention of IE is not recommended during delivery (III‐C).

Congenital cardiac disease

Jul 20, 2020 | Posted by in GYNECOLOGY | Comments Off on 26: Cardiovascular disease
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