Preoperative factors for early mortality in patients with HLHS undergoing the Norwood procedure

Hypoplastic left heart syndrome (HLHS) is characterized by hypoplasia of the left heart and outflow tract. The three-stage surgical reconstruction of heart consists of circumventing the underdeveloped left ventricle by connecting right ventricle to systemic circulation and grafting a passive flow conduit which shunts venous blood into pulmonary artery. First stage surgery (Norwood) has the highest mortality among common congenital surgeries (7-19%) followed by a high risk interstage (IS) phase where additional 4-15% of infants die. A retrospective chart review of HLHS patients was conducted at Cook Children's hospital between January 2007 through January 2017. The objective of the study was to identify preoperative risk factors that may lead to premature death during IS. Univariate logistic regression analyses were used to determine whether feeding, intubation, and ECMO predicted mortality. IS was defined as time following Norwood procedure until Glenn, the second stage of reconstruction. Analysis revealed that receiving preoperative Norwood feeding intubated prior to surgery was associated with lower mortality (OR=0.42, CI=0.20-0.90, p= 0.025). Furthermore, intubation prior to surgery (OR=1.73, CI=1.05-2.85, p= 0.03) and pre-operative extracorporeal membrane oxygenation (ECMO) procedures (OR=2.83, CI=1.12-7.19, p=0.028) were associated with a higher IS mortality. Findings suggest a positive relationship between pre-operative respiratory interventions and increased rate of mortality during IS. Elucidation of this relationship suggests that pre-operative pulmonary status of the patient may be a leading prognostic factor on infant death between Norwood and Glenn. Consequently, a closer look at HLHS palliative protocol is warranted.