Separation of Conjoined Hearts in Thoracopagus Twins

Introduction

Eight hours after the delivery of thoracopagus twins, the right twin developed circulatory failure forcing an emergency separation to save the left twin. The twins had conjoined livers and conjoined hearts in a common pericardial cavity, and they appeared to have no ventricular-level fusion.

Procedure

Surgery was performed on the second day of life using general anesthesia and full invasive monitoring. The twins were placed with the ventral side uppermost, the ventral side being the side with the greater interareolar distance. After skin preparation and draping, an incision was made along the line of somatic fusion, and the abdomen was entered to separate the conjoined livers and intestines.

Moving to the chest, the two diaphragms were conjoined and the two hearts were in a common pericardial cavity. The heart of the right twin was clearly hypoplastic but had good contractility. The preoperative echocardiogram had shown this twin’s heart to have functionally single ventricle morphology. The left twin had a normal-sized four-chambered heart on echocardiogram, and this appeared to be the case at surgery. The caval and pulmonary venous connections were separate and normal for each heart. At the atrial level, a short tubular bridge of myocardium connected the two atrial masses. There was no connection at the ventricular level, and so the hearts could be separated by simple division of the atrial bridge. The hearts were thus separated completely. Subsequently, the surgical incision was carried round dorsally through the layers of the chest and abdominal walls to effect complete separation of the twins. Care was taken to commit as much of the conjoined chest and abdomen as possible to the healthy twin to limit the potential for flail chest and abdominal compartment syndrome.

The chest wall of the healthy twin was reconstructed with a mesh as shown in the video. The abdomen was closed primarily without tension.

Outcome

As expected, the heart of the right twin could not support an adequate cardiac output, and death ensued shortly after separation. The apparently healthy twin remained hemodynamically stable postoperatively, maintaining adequate tissue perfusion without inotropic support. However, her respiratory function remained suboptimal, and it gradually deteriorated into refractory respiratory failure until her death on the eighth postoperative day.

Comment

Three reports from the UK [1], USA [2], and South Africa [3] represent the largest surgical experience of separation of conjoined hearts in thoracopagus twins gathered over three to four decades. Our limited experience fits fairly well with these reports: in the current era, successful surgical separation of conjoined hearts in thoracopagus twins remains largely elusive. Pulmonary hypoplasia ostensibly results from the lungs having to develop within the thoracic volume of half a conjoined body cavity. In addition, impaired ventilatory mechanics resulting from postoperative flail chest, pneumothoraces, a restrictive chest wall, and respiratory infection all contribute to make respiratory insufficiency an important confounder of survival after an apparently successful surgical separation.

References

1. Andrews RE, McMahon CJ, Yates RW, et al. Echocardiographic assessment of conjoined twins. Heart. 2006;92(3):382-387.
2. Thomas Collins R 2nd, Weinberg PM, Gruber PJ, St John Sutton MG. Conjoined hearts in thoracopagus twins. Pediatr Cardiol. 2012;33(2):252–257.
3. Rode H, Fieggen AG, Brown RA, et al. Four decades of conjoined twins at Red Cross Children’s Hospital–lessons learned. S Afr Med J. 2006;96(9 Pt 2):931-940.