Various modalities for evaluation of a fused heart in conjoined twins

Conjoined twins are a rare congenital anomaly with an estimated incidence of 1/50,000 to 1/100,000. Among thoracopagus conjoined twins, 75% have a fused heart. We compare the usefulness of various modalities for evaluating cardiovascular structure in fused-heart conjoined twins. We report a series of 20 sets of thoracopagus conjoined twins as well as the results of a PubMed database literature review literature from 1982 to 2009. Twenty sets of fused-heart thoracopagus conjoined twins were evaluated by echocardiography, cardiac catheterization, magnetic resonance image (MRI), and three-dimensional computed tomography angiography (3D-CTA). Imaging results were compared to findings at surgery or autopsy. All sets of conjoined twins underwent postnatal echocardiography; 11 sets (55%) underwent cardiac catheterization; 4 sets (20%) underwent MRI; and 1 set (5%) underwent 3D-CTA. All intracardiac anatomy (ICA) was identified by echocardiography. Cardiac catheterization, MRI, and 3D-CTA were able to identify extracardiac vascular structures as well as the ICA. 3D-CTA, which can be performed as early as the first week of life, is a noninvasive, less expensive, and the safe examination with minimal risk due to its short procedural time. Three-dimensional CTA is an effective and safe modality for evaluating the cardiovascular anatomy of fused-heart conjoined twins before surgery.