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

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1 European Heart Journal Supplements (2014) 16 (Supplement B), B32 B36 The Heart of the Matter doi: /eurheartj/suu008 Evaluation of cardiovascular anomalies in conjoined twins: a single-center experience from King Abdulaziz Cardiac Center Abdulsalam Alsayad 1, Abdu AlKhatabi 1, Mohammed H. Alghamdi 1,2, Abdullah Al Rabeeah 3, Fahad Alhabshan 1,4, and Riyadh M. Abu-Sulaiman 1,4 * 1 Division of Pediatric Cardiology, King Abdulaziz Cardiac Center, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, PO BOX 22490, Riyadh 11426, Kingdom of Saudi Arabia 2 Pediatric and Fetal Echocardiography Laboratory, King Fahad Cardiac Center, King Saud University, Riyadh, Kingdom of Saudi Arabia 3 Division of Pediatric Surgery, Department of Surgery, King Abdulaziz Medical City, Ministry of National Guard - Health Affairs, Riyadh, Kingdom of Saudi Arabia 4 King Saud bin Abdulaziz University for Health Sciences, Riyadh, Kingdom of Saudi Arabia KEYWORDS Conjoined twins; Congenital heart disease 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. Introduction The incidence of conjoined twins (ConTw) is rare, ranging from one in to one in , which accounts for 1% of monochorionic twin pregnancies. 1,2 About 60% of these twins are stillborn or die shortly after birth. 3 A higher incidence was observed in girls with a female-to-male ratio * Corresponding author. Tel: , Fax: abusulaiman@mailzone.com of 3 : 1. 4 Twins are classified according to the major site of union. Thoracopagus (joined at the thorax) twins are the most common type, accounting for 40% of cases, followed by omphalopagus (joined at upper abdomen + lower thorax), accounting for 32%. Other forms are: pygopagus (joined at the sacrum and coccyx), ischiopagus (joined at the lower abdomen below umbilicus down to the pelvis/perineum), and craniopagus (joined at the cranial vault). The term parapagus is used to describe a variable degree of side-to-side fusion. 2,5 Published on behalf of the European Society of Cardiology. All rights reserved. & The Author For permissions please journals.permissions@oup.com

2 Evaluation of cardiovascular anomalies in conjoined twins B33 Table 1 Type of conjoined twins and classification of congenital heart disease Classification of CHD Conjoined twins (42) Total Symmetrical (35; 83.3%) Asymmetrical (7; 16.7%) Ventral/lateral conjunction (29; 69%) Thoraco-omphalo-ischiopagus (variable degrees of conjunction) Dorsal conjunction (6; 4.3%) Craniopagus Pygopagus Thoracopagus Omphalopagus Ischiopagus Parapagus Class 1 (both are normal) 2 (66.7%) 3 (100%) 2 (18.2%) 1 (33.3%) 2 (28.6%) 10 (23.8%) Class 2 (both are abnormal) Both minor (2a) 3 (27.25%) 2 (66.7%) 1 (100%) 2 (28.6%) 8 (19%) Both major (2b) 13 (92.85%) 13 (31%) One minor and one major (2c) 1 (7.15%) 2 (18.2%) 1 (14.27%) 4 (9.5%) Class 3 (one normal and one abnormal) Minor (3a) 1 (33.3%) 3 (27.25%) 1 (14.27%) 5 (11.9%) Major (3b) 1 (9.1%) 1 (14.27%) 2 (4.8%) Total 3 (7.15%) 3 (7.15%) 14 (33.3%) 11 (26.2%) 3 (7.15%) 1 (2.35%) 7 (16.7%) 42 (100%) Bold values indicate the total for both numbers and percentages. The overall incidence rate of congenital heart disease (CHD) in ConTw is 66%. 5 Thoracopagus twins carry the highest incidence rate of cardiac malformations reaching up to 94.4% for major CHD and 72.2% for cardiac defects with single-ventricle physiology. 6 The extent of cardiac fusion and the severity of cardiac abnormalities play a major role in the medical decision of surgical separation and in long-term survival. We report the association of cardiovascular anomalies in 42 sets of ConTw who have been referred over a period of 17 years from 1997 to 2014 at our center for cardiac evaluation with regard to their potential separation. To the best of our knowledge, this is the largest single-center series of ConTw that describe the presence of CHD in this challenging population. Methods Between 1997 and 2014, 42 sets of ConTw with different levels of fusion were referred to our institution to be assessed for the feasibility of surgical separation. Twenty-six of 40 sets (65%) were female. In two sets of ConTw, gender was not confirmed since diagnosis was made during fetal life. Thirty-five sets of twins (83.3%) were symmetrical (3 craniopagus, 3 pygopagus, 14 thoracopagus, 11 omphalopagus, 3 ischiopagus, and 1 parapagus twins), whereas 7 sets of twins (16.7%) were asymmetrical with a variable degree of thoraco-omphalo-ischiopagus fusion. Full cardiac evaluation was performed in all sets by comprehensive two-dimensional (2D) transthoracic echocardiography modified as needed by the accessibility of subcostal and precordial views. ConTw were classified according to the presence or absence of minor/major cardiac abnormalities. Class 1 indicates that both twins had normal hearts. Class 2 means that both twins had abnormal hearts, whichwas further subdividedinto further subclasses 2a if both had minor CHD, 2b if both twins had major CHD, and 2c if one twin had minor while the other had major CHD. Class 3 indicates that one twin had a normal heart while the other had either minor 3a or major 3b CHD. Major CHD was defined as any cardiac abnormality that required medical or surgical intervention in the first year of life. In nine sets of twins (21.4%), cardiac diagnosis was made by fetal echocardiography. Most of them were thoracopaus (six sets), while three were found to be thoraco-omphalopagus. All of these nine sets of twins had major CHD in terms of a fused heart chamber or single-ventricular anatomy. Transoesophageal echocardiography was performed in only one set. Three sets of twins required further cardiac imaging, including computed tomographycardiacangiography(cta)intwosetsandcardiacmagnetic resonance imaging (CMRI) in one set. This was necessary to assess the vascular anatomy that was not clear by 2D echocardiography. Results Table 1 summarizes the classification used which can be summarized as follows: 10 sets were in Class 1 (23.8%), 25 sets in Class 2, and more precisely 8 in 2a, 13 in 2b, and 4 in 2c. Figure 1 shows the level of sharing/fusion in 14 sets of thoracopagus ConTw. All of them had major CHD. Two sets (14%) shared the pericardium only, whereas 3 sets (21.5%)

3 B34 A. Alsayad et al. Figure 1 Flowchart of our series of thoracopagus conjoined twins with classification of their congenital heart disease and fusion level of cardiac structures. Figure 2 Single fused heart: two-dimensional and two-dimensional colour flow Doppler echocardiography images (A E) and schematic diagram (F) showing major cardiac abnormalities with fusion of both hearts at the atrial and ventricular level in one set of conjoined thoracopagus twins (Twin A and Twin B). There are two atrial (a) and four ventricular masses (v). Each heart gives rise to aorta (Ao) and pulmonary artery (PA) to each twin.

4 Evaluation of cardiovascular anomalies in conjoined twins B35 Figure 3 Computed tomography angiography and three-dimensional reconstruction images from conjoined twins with thoraco-omphalopagus showing a single fused heart at the atrial and ventricular level. Maximum intensity projection (MIP) images in the sagital (A) and axial (C) planes as well as three-dimensional reconstruction (B) and (D) delineate clearly the vascular structure for both twins. There are two atrial (a) and four ventricular (v) masses. Each heart gives rise to aorta (Ao) and pulmonary artery (PA) to each twin. were fused at the atrial level, 2 sets (14%) at the ventricle level, and 7 sets (50%) had a severely malformed single heart with fusion at both the atrial and ventricular level (Figures 2 and 3). Major CHD was far more common in thoracopagus twins (14/14 sets; 100%), compared with omphalopagus twins (3/11 sets). No major cardiac abnormalities were detected in the other forms of ConTw. Discussion Although the literature related to ConTw is extensive, only few large series have been reported. Similar to previous reports, 2,6 our study confirmed that thoracopagus connection is the most common form of ConTw with a higher incidence rate in female. Thoracopagus twins are associated with a greater degree of cardiac fusion and carry a higher risk of cardiac malformations compared with other forms of connections. 3 An accurate delineation of cardiac anatomy and the degree of cardiac fusion is essential to determine the feasibility of surgical separation. In our series, all sets of twins who had fused hearts at atrial, ventricular, or both levels were considered not to be candidates for surgical separation, and as expected none survived. Our experience has been accumulated through the years during which the quality and availability of imaging modalities has changed considerably. Although 2D echocardiography performed by a skilled operator continues to be the initial tool to assess cardiac fusion, anatomy, and function, new imaging modalities such as CTA and CMRI are more accurate with regard to the definition of fusion and to the great vessels anatomy. 7 MRI has an increasing role in multisystem evaluation of ConTw before separation. It offers the advantage to allow generation of three-dimensional (3D) image reconstructions in any plane and orientation as well as to provide information about intra-cardiac and great vessels anatomy. The support from the advances in imaging, multidisciplinary approach, and improvements in intensive care management has resulted in improvement in surgical separation over time. In any case, separation should be only performed in specialized tertiary centers familiar with this kind of complex surgery. 5,8 Acknowledgements We thank Prof. Talat M. Yelbuz, MD, PhD, for his help during drafting, critical reading, and revision of this manuscript. Conflict of interest: none declared.

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