Evaluation of cardiovascular anomalies in conjoined twins: a single-center experience from King Abdulaziz Cardiac Center

The aim of the study is to describe varieties of congenital heart disease (CHD) in different types of conjoined twins (ConTw). This is a retrospective (from 1997 to 2014) analysis of 42 sets of ConTw with different levels of body and/or organ fusion, referred to our center for cardiac evaluation prior to separation. Conjoined twins were classified into Classes 1, 2, and 3 according to heart abnormalities and further subclasses of a, b, and c according to minor or major heart disease. Of the 42 sets, there were 35 sets of twins (83.3%) who were symmetrical including 3 craniopagus, 3 pygopagus, 14 thoracopagus, 11 omphalopagus, 3 ischiopagus, and 1 parapagus. Seven sets of twins (16.7%) were asymmetrical with a variable degree of thoraco-omphalo-ischiopagus fusion. Twenty-six of 40 sets (65%) were female. Overall incidence rate of cardiac abnormalities was 76.2%. Major cardiac abnormalities were common in thoracopagus twins (14 sets). Two sets (14%) shared the pericardium, whereas three sets (21.5%) were fused at atrial level, two sets (14%) at ventricle level, and seven sets (50%) had a severely malformed single heart with fusion at both the atrial and ventricular level. Conjoined twins have a high incidence of CHD. All symmetrical thoracopagus tetrapus twins had major cardiac abnormalities precluding their separation and all of them did not survive. Incidence of major cardiac malformations was less in the other types of ConTw.