Cardiovascular anomalies in conjoined thoracopagus twins

Necropsy findings in 3 cases of conjoined thoracopagus twins are presented. Conjoined hearts were seen lying in a common pericardial cavity. In 2 cases the common atrial complex was incompletely divided into the atrial cavities of the twins by ridges arising from the floor of the cavity. In 1 case the atrial division was better defined and the interatrial septal defect of septum secumdum type was seen. Pulmonary veins opened normally into the atrial chamber only in 1 case, in the other 2 cases, these veins opened into the inferior vena cava and the liver respectively. Ventricular chambers were common in 2 cases with 3 rudimentary atrioventricular openings guarding the inlet and multiple VSD of muscular type. In 1 case one twin had 2 completely separated ventricular cavities and the other twin had partially separated ventricular cavities with a muscular VSD. Great vessels showed transposition in all the cases. In 1 case d-transposition of a rare variety was seen which was associated with a subaortic as well as subpulmonic conus. Persistent ductus arteriosus was a cmmon feature and valvular type of pulmonic stenosis was seen in 2 cases.