A single-center experience with 12 consecutive cases of pregnancy among patients with membranous ventricular septal aneurysm

Membranous ventricular septal aneurysm (MVSA) is an uncommon anomaly of the membranous portion of the cardiac septum. Aneurysmal bulging begins in a weak or incomplete cardiac septum that is unable to overcome the differential pressure between the left and right ventricles. MVSA occurs as an isolated abnormality or being associated with other cardiac malformations. MVSA is a well-recognized risk factor for outflow tract obstruction and embolisms, and is related (either directly or secondary to) to rupture, bacterial endocarditis, and arrhythmia. However, most patients with this cardiac anomaly were asymptomatic, and the aneurysms were discovered incidentally on echocardiography. Without diagnosis, unforeseen problems or unexpected deaths may occur in patients who are under a conditions of increased cardiovascular stress, such as pregnancy. The outcome of pregnancy and delivery in patients with MVSA has not been reported in the literature. We present 12 cases of pregnant women with incidentally discovered MVSA and discussed our experience in managing these cases.

This was a retrospective study approved by the Institutional Review Board of West China Second University Hospital. We reviewed the medical records of 591 pregnant women with congenital heart disease (CHD) who were admitted at West China Second University Hospital, a tertiary referral center, between May 2008 and March 2015. Prevalence of CHD in pregnancy was 0.88% (591/66988). Among 591 pregnant women with CHD, 12 cases of MVSA (2.03%) were diagnosed.

Ventricular septal aneurysms are extremely rare clinicopathological entities that include congenital muscular interventricular septal aneurysm (CMISA) and membranous ventricular septal aneurysm (MVSA) [2, 3]. Membranous ventricular septal aneurysm was first described as a congenital malformation in 1826 by Laennec [4]. It is thought that the membranous septum remains weak during embryonic development, and forms an aneurysm of the membranous septum—bulging toward the right under the pressure of left ventricle. It has also been proposed that MVSA could be acquired—the consequence of delayed natural closure of a ventricular septal defect after birth [5‐7]. Indeed, MVSA is primarily associated with a history of spontaneous closure of a small membranous ventricular septal defect in childhood [2]. Patients with MVSA may incur potential cardiac complications, such as aortic valve prolapse, right ventricular outflow obstruction, tricuspid valve insufficiency, arrhythmia, rupture, thromboembolism, and bacterial endocarditis [8‐12]. However, most MVSA patients are asymptomatic, the physical examination and electrocardiogram may fail to identify MVSA in the absence of ventricular arrhythmia or other complications [13]. MVSA may provide an occult cardiac source of cerebral or systemic embolus [14]. Furthermore, congestive heart failure may occur because of adverse effects of MVSA on systolic function [9].

Our subjects were asymptomatic before conception, or experienced mild symptoms, and physician did not pay enough attention to them. During pregnancy, the most common complications in our cases were pulmonary arterial hypertension, atrioventricular valve diseases and arrhythmia. No incidence of thromboembolism was found, and this may have assisted our clinical outcomes, which were basically good in spite of varied degrees of pulmonary arterial hypertension in 7 patients. The numbers of patients in the subgroups were too small to conduct further statistical analysis.

Asymptomatic patients with MVSA should be followed closely for potential cardiac complications. This is especially important for the cases in the setting of pregnancy [15‐17]. Pregnancy places extra load on the heart, and can affect cardiac function, leading to increased maternal morbidity and perinatal morbidity [18, 19]. In general, women with NYHA class > III have a relatively poor prognosis during pregnancy [20]. In our study, one case with NYHA class IV and severe pulmonary hypertension had to terminate pregnancy at 17 weeks of gestation; and one case with NYHA class IV expired.

We assumed that pregnant women with MVSA were at risk for maternal and neonatal complications, although the outcome in pregnancy with MVSA has not been reported in the literature. There was indeed a high rate (> 80%) of obstetric events involving prematurity, PROM, preeclampsia, breech presentation, GDM and postpartum hemorrhage. Mothers with CHD also have a high incidence of fetal complications such as miscarriage, premature births, low birth weights, respiratory distress syndrome, and cardiac anomalies [21]. In this study, neonatal congenital heart disease (Tetralogy of Fallot) and SGA at birth (1550 g at 34 + 4 weeks, survived) occurred in a twin gestation, the former expired and the latter survived. An additional singleton baby was born with SGA (1095 g at 30 + 4 weeks gestation) and expired on day 2 post birth.

Due to high risk of complications during vaginal delivery, a cesarean section delivery is usually recommended for woman with cardiac disease, since extra cardiac burden from prolonged laboring process may be avoided [17, 22]. In the current study, except one terminated pregnancy in the second trimester, all of the remaining patients delivered by cesarean section under combined spinal epidural anesthesia, epidural anesthesia or general anesthesia. Except one maternal death from pulmonary infection and heart failure (also with severe pulmonary arterial hypertension, NYHA class IV), all other patients survived. Almost all of them suffered cardiac complications such as mild-to-moderate pulmonary arterial hypertension, atrioventricular valve diseases and arrhythmia, but none of them developed thromboembolism. The relative good outcomes in our patients may be at least partially owing to the absence of severe hypertension, cardiac failure and cerebral and pulmonary embolism. In addition, comprehensive interdisciplinary management among the cardiologist, obstetrician, anesthetist, and neonatologist, and detailed plans for delivery may have improved the prognosis [23].

Pregnancy with MVSA presents an increased risk of cardiac complications. Maternal and neonatal risks seem to be associated with heart functional classification, pulmonary hypertension and history of serious cardiac arrhythmia. Accurate diagnosis and care by a multidisciplinary team should be the best approach in order to improve prognosis in these patients.