Women with congenital heart disease experience longer life expectancy and improved general health in recent years. They are reaching reproductive age and considering pregnancy in increasing numbers.1 These women face uncertainty in their reproductive years. Pregnancy presents a challenge due to the hemodynamic stresses of increased blood volume and cardiac output and decreased peripheral vascular resistance. Labor and delivery represents a particularly precarious situation, given the physiologic stress of labor and the fluid shifts that occur at the time of delivery. However, studies have suggested that many women with congenital heart disease experience favorable maternal and fetal outcomes.1–15 The challenge that exists for doctors and patients is determining which patients are still at risk for serious consequences of pregnancy.
Congenital heart disease represents a diverse set of lesions, and thus, a heterogeneous group of patients. It is critical that doctors, women, and their families understand the risk pregnancy poses to the individual patient and her offspring. Care of these lesions has evolved over time, and many women in whom pregnancy previously had been discouraged are experiencing healthy pregnancies. Recent studies on pregnancy outcomes have included both congenital and aquired heart disease2 or included women with mild or completely repaired cardiac lesions in whom good pregnancy outcomes are expected.1,12 Our primary objective was to examine cardiac, obstetric, and neonatal outcomes of pregnancy in a contemporary population of women with complex cardiac anomalies in whom the risk of pregnancy has not been clearly defined. The population was categorized into groups based on the cardiac lesion to identify trends that occur in patients with similar types of altered cardiac structure and physiology and to look for patterns among women with cardiac deterioration or poor obstetric and neonatal outcomes.
MATERIALS AND METHODS
Subjects with congenital heart disease who delivered at Columbia University Medical Center between 2000 and 2007 were identified using birth logs and delivery records maintained by the Department of Obstetrics and Gynecology. This list was cross-referenced with the individual clinic lists maintained by perinatologists and cardiologists. Women were included in our cohort if they had documented congenital cardiac disease and carried the pregnancy to 20 weeks of gestation or longer. Pregnancies that resulted in miscarriage or elective termination before 20 weeks of gestation were excluded from analysis, because ascertainment of these pregnancies from the existing perinatal database is incomplete. Patients were excluded if they had a diagnosis that was attributed to rheumatic heart disease or hypertrophic cardiomyopathy or if they had a minor congenital anomaly such as mitral valve prolapse with mild regurgitation. Also excluded were patients with simple congenital disease that had been completely repaired, such as atrial septal defects or small ventricular septal defects. The underlying primary congenital heart defect was classified by a single board-certified cardiologist after review of medical records and available echocardiograms into the following categories: right and left-sided obstructive lesions, right and left-sided regurgitant lesions, shunts, conotruncal defects, and miscellaneous lesions.
Inpatient and outpatient records of both the mother and infant were reviewed, using electronic and paper charts maintained in the hospital database. Data regarding maternal demographics, including age, race, marital status, and insurance information, was abstracted. Data were collected regarding baseline maternal health, including age, lesion classification, ventricular dysfunction at baseline, degree of valvular regurgitation at baseline, use of anticoagulation, need for cardiac medication throughout pregnancy, a history of prior cardiac or obstetric events, cesarean delivery, or pregnancy complicated by multiple gestation.
Gestational age at delivery, method of delivery, indication for obstetric intervention, and use of invasive monitoring during the labor process were enumerated for the study population. Frequencies of both cardiac events and obstetric outcomes were determined for the entire cohort and compared by the underlying morphology of the congenital defects.
An adverse cardiac event was defined as the occurrence of maternal death, congestive heart failure, myocardial infarction, stroke, sustained arrhythmia requiring treatment or the need for urgent cardiac intervention during the pregnancy, delivery, or the first 6 weeks of the postpartum period. An adverse obstetric outcome was defined as preterm birth, small for gestational age as defined by birth weight less than 10th percentile,16 preeclampsia, stillbirth, or neonatal intensive care unit admission.
Data were evaluated to look for patterns that might describe the experience of this cohort of patients in pregnancy. The sample size was too small to allow for significant statistical evaluation. The study was approved by the Columbia University Medical Center Institutional Review Board.
One hundred thirteen patients with structural congenital heart disease and a completed pregnancy were identified. After review by a cardiologist, 44 patients were excluded due to low-risk lesions. These were defects that had been completely repaired, or were so small as to be considered clinically insignificant: 35 small septal defects, two mild pulmonary stenosis, four bicuspid aortic valves, and three patent ductus arteriosus. After exclusion, 74 pregnancies in 69 women remained in the cohort. These patients were categorized by a single cardiologist based on their primary lesion as illustrated in Table 1. There were four patients with miscellaneous lesions who did not fit into one of these categories. One patient had a history of a Fontan procedure for a single ventricle. In addition, there were several patients with shunts who had secondary lesions as indicated in Table 1.
The median age of the women was 28 years old, and median parity was zero (Table 2). Labor was allowed in 55 (74.3%) patients, and there were 43 vaginal deliveries, eight of which were forceps-assisted. The remaining 31 (41.9%) had cesarean deliveries. Two cesarean deliveries were performed for worsening maternal cardiac status; the rest were for obstetric indications. Eleven deliveries were elective repeat cesareans. There were five cases of nonreassuring fetal status, seven arrest or protraction disorders, five cases of malpresentation, and one placenta previa. Preeclampsia occurred in seven (9.5%) cases, none of which were considered severe. In six patients, five of which were in the shunt category and one with a right-sided obstructive defect, invasive monitoring with Swan-Ganz catheters, arterial lines or central venous lines was employed to monitor volume status and titrate medications. Three patients required pressors during labor and delivery, and four required diuretics.
There were 24 (29.7%) antepartum admissions, which occurred at a median gestational age of 30 weeks. The median length of stay was 11 days, and 3 patients required multiple admissions. The majority of admissions were for obstetric indications, but there were six patients admitted for worsening maternal cardiac status, five patients with shunt-type lesions, and one with a conotruncal defect.
The majority of patients experienced uncomplicated labor and delivery. Median birth weight was 2,905 g, and median 5-minute Apgar score was 9 (Table 3). The rate of preterm delivery was 17.7% overall. For the year 2007, the rate of preterm birth at our institution was 16.5%, and median birth weight was 3,073 g. Sixteen infants (21.6%) were small for gestational age upon delivery. There were four very low birth weight infants (less than 1,500 g), occurring in two patients with shunts and one patient with a left obstructive lesion. Two of these infants were a set of twins born to a patient with a shunt-type lesion. There were 20 complications in 14 patients with shunt-type lesions, occurring at a rate of 73.7%, and there were 12 complications in nine patients (47.4%) with conotruncal defects. The frequency of obstetric complications was greater than 50% in right regurgitant and left obstructive groups as well, although the total number of patients in those groups was smaller.
Adverse cardiac events were most likely to occur in the postpartum period. Of the 21 cardiac events, four occurred antepartum, one intrapartum, and the remaining 16 in the first 6 weeks after delivery (Table 4). Seven out of the 19 patients with shunts experienced cardiac events. The most common required intervention was urgent repair of the original cardiac lesion in the early postpartum period. Several of the patients in the shunts and conotruncal lesion categories had multiple cardiac events. The two maternal deaths were both in patients with shunt-type lesions. One occurred in a patient with an atrial septal defect and pulmonary hypertension who was delivered at 34 weeks for worsening hypoxia. During her induction, she had a cord prolapse and underwent emergent cesarean delivery. After delivery, her symptoms worsened, and she was taken for urgent repair of the atrial septal defect on postoperative day 4. After surgery, she suffered complete cardiovascular collapse. The other death occurred in a patient with an aortopulmonary window who was delivered for worsening maternal oxygenation at 31 weeks by cesarean for malpresentation. She had persistent hypoxia postpartum, and was placed on extracorporeal membrane oxidation on postoperative day 4. She died 15 days postpartum. In both cases, the infants required initial stabilization in the neonatal intensive care unit, but were vigorous and healthy and discharged to the well-baby nursery after a few days.
Given the diverse nature of congenital heart disease, it is difficult for clinicians to generalize outcomes for the individual patient. In this study, we examined patients with significant structural congenital cardiac disease to identify which patients are at greatest risk for adverse outcomes. Other studies have identified risk factors for adverse outcomes, including poor functional status, cyanosis, left heart obstruction, pulmonary hypertension, reduced left ventricular ejection fraction, right ventricular dysfunction, prior congenital heart failure, myocardial infarction, arrhythmia, or stroke.1,3,5–7,11,12 By categorizing these patients according to lesion type, we were able to examine trends based on similar cardiac physiology. In our cohort of women with major congenital heart lesions, the cardiac outcomes of most concern occurred in patients with shunts. Several of the patients in this category had secondary lesions in addition to the primary shunt lesion. A few patients in the conotruncal and left regurgitant categories also experienced serious cardiac events.
Although many patients experienced uncomplicated labor and delivery, we observed an elevated rate of preterm birth (17.7%) and small for gestational age infants (21.6%) compared with the general population.17 The greatest frequency of these events was again seen in the shunts category, although there were also large proportions of the right obstructive, left regurgitant, and conotruncal lesion categories with adverse obstetric outcomes. Cardiac events occurred in 20.2% of pregnancies, which is similar to rates observed in other studies.1,12 The majority of cardiac events occurred during the postpartum period. Although the rate of cesarean delivery was elevated at 41.9 %, compared to a national rate of 30.3%,18 the gestational age at delivery, birth weight, and Apgar scores were similar to those experienced by the general population. A large number of antepartum admissions were required in this population, yet only a minority of those admissions was due to worsening maternal status. It is unclear from these data whether the increased rate of admission for obstetric indications is influenced by concerns about the patient’s underlying cardiac status. There were increased numbers of preterm births and neonatal intensive care unit admissions, similar to what is observed in other populations of patients with congenital heart disease.1,19 These observations are most likely related to iatrogenic prematurity in patients whose delivery is prompted by maternal indications. The increased frequency of small for gestational age infants is of concern and warrants further investigation.
A major strength of this study is that these women were cared for at a single medical center, allowing for consistency of care and interpretation of data. This study presents the experience of a cohort of patients with significant cardiac defects in whom the risks to pregnancy are not well-described. However, there are several potential biases that must be taken into account. Patients with higher functional status are more likely to survive to reproductive age and consider pregnancy, which may lead to selection bias of healthier patients at baseline. Limiting the study to patients with completed pregnancies similarly selects for more favorable outcomes. The small sample size of this cohort limits its ability to specifically identify risk factors and predict outcomes for future patients. In addition, we did not include New York Heart Association (NYHA) class data in our study because it was not consistently available in all of the patients’ records. Although it has been suggested that NYHA class is an important measure in determining the risk of pregnancy, many of these patients are cyanotic at baseline, and NYHA data may not be pertinent in this population. Finally, we did not follow patients beyond the initial postpartum period, and so we do not have information about long-term cardiac function after pregnancy.9
Multicenter prospective cohorts should be established and followed using objective measures of cardiac function to better clarify which patients are at greatest risk of adverse outcomes and who might benefit from invasive cardiac monitoring during labor and delivery.2–3,14 Follow-up beyond the initial postpartum period may also help identify what the long-term effect of the stress of pregnancy is on cardiac function in patients with congenital heart disease.
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