Propranolol Treatment for Postoperative Chylothorax

Postoperative chylothorax is a serious complication after open heart surgery for pediatric patients with congenital heart disease (CHD). While it was thought to be mechanical injury to the thoracic duct, recent research demonstrated that there are intrinsically abnormal lung lymphatics in CHD patients, and after open heart surgery, the fluid shifts that occur overwhelms these abnormal lung lymphatics. As a result, postoperative chylothorax occurs. Propranolol has been found to be helpful in resolving postoperative chylothorax very quickly (9 days) in a subset of postoperative chylothorax patients (60%). However, it is not known why some patients respond and some do not. The investigators hypothesize that propranolol is safe to use in this patient population, and that certain clinical factors will predict propranolol response, but more importantly, some clinical factors can be optimize to allow more patients with postoperative chylothorax to respond to and benefit from propranolol. In order to improve the understanding of how propranolol works and to maximize benefit to patients, the investigators propose to perform a prospective, randomized, double-blind clinical trial to learn how to best use propranolol in patients with postoperative chylothorax.