Transcatheter balloon atrial septostomy in thoraco-omphalopagus conjoined twins

Introduction

Conjoined twinning is a rare congenital anomaly with a reported incidence of 1 in 50,000-200,000 births [1, 2]. Fusion at the thoracic level (thoracopagus) is the most common variety (40% of cases) followed by the abdomen (omphalopagus, 32%) [1]. Cardiac anomalies are common in these patients and range from shared pericardium to fused atria and ventricles [1]. Congenital heart disease (CHD) is common in addition to cardiac fusion in these children [3]. Perinatal outcomes are determined by the severity of cardiac involvement. Overall survival for conjoined twins is dismal at 25% [4]. Survival after successful separation for a conjoined twin with fused hearts is even more rare, with reported survival of 10% if fused at the atrial level and 0% if fused at the ventricular level [3, 5].
Cardiac catheterization has been used in diagnosis of CHD in these patients [3]. We report a case of thoraco-omphalopagus twins with atrial fusion, where the index twin had CHD and required transcatheter balloon atrial septostomy (BAS) at 3 months of age prior to surgical separation. Balloon atrial septostomy played a key role in medical management and successful cardiac surgery.

Case report

There was prenatal diagnosis of thoraco-omphalopagus conjoined twinning of two female fetuses with union from just cranial to the manubria, to just caudal to a common umbilicus, with a shared liver but otherwise separate intraabdominal and intrathoracic contents. Fetal echocardiography and post-natal transthoracic echocardiography identified separate cardiac masses with a shared pericardial sac. In this case, the index twin (twin B) had levocardia with a levoposed cardiac apex, tricuspid atresia with dextro-transposition of the great vessels and a large bulboventricular foramen, and secundum atrial septal defect. The co-twin (twin A) had dextroversion of the heart, but otherwise normal cardiac structure. In addition, there was a small vermiform vascular communication between the right atrial appendage of the index twin and the dextroverted/anterior left atrium of the co-twin. Flow across this tiny connection could only be demonstrated consistently well in the fetal echocardiograms. The twins were born by Caesarean section at 33 + 6/7 weeks gestational age.
The hemodynamics in the conjoined pair were complex. Using a combination of transthoracic echocardiography and CT angiography, arterial communications between the twins in the hepatic artery...


View full text...