Normothermic versus Hypothermic Norwood Procedure

Background:

Either deep hypothermia with circulatory arrest (CA) or hypothermic perfusion with antegrade selective cerebral perfusion (ASCP) is routinely used during Norwood stage I procedure for hypoplastic left heart syndrome (HLHS). Normothermic perfusion is currently applied in a vast variety of pediatric patients with heart. Therefore, as a continuation of this approach, normothermic perfusion was also used for patients with HLHS. The aim of this study was to compare early outcomes of patients undergoing Norwood operation with ASCP under hypothermia versus normothermia (>34°C).

Methods:

From July 2005 to August 2020, 117 consecutive patients with HLHS underwent Norwood operation; 68 (58.2%) under hypothermia; and 49 (41.8%) under normothermia. ASCP flow was adjusted to maintain right radial arterial pressure at greater than 50 mmHg, maintaining cardiopulmonary bypass flow of at least 20 ml kg-1 min-1. Baseline characteristics, operative data and postoperative outcomes including lactate recovery time, were compared.

Results:

Baseline characteristics and cardiovascular diagnosis were similar in both groups. The normothermic group had significantly shorter mean bypass time (90.3 min ±31.6 vs 123.6 min ±25.3); mean cross-clamp time (45.2 min ±16.35 vs 81.9 min ±16.34); and, shorter selective cerebral perfusion time (25.6 min ±13.84 vs 47.3 min ±14.35) (pv <0.001). There was no statistically significant difference during post-operative course in terms of: revision for bleeding; delayed sternal closure time; peritoneal dialysis; neurological events; renal failure; infections, respiratory and heart failure; ECMO support; lactate level during the first postoperative day; ventilation time; ICU and hospital stay. Lastly, there was no difference in in-hospital mortality among the groups; 9 (18.4%) in the normothermic group, and 10 (14.9%) in the hypothermic group (pv 0.81); overall mortality was 19 (16.2%).

Conclusions:

Normothermic Norwood stage I procedure with selective cerebral perfusion is feasible and safe in terms of in-hospital mortality and short-term results. It is comparable to standard hypothermic Norwood with selective cerebral perfusion. Further investigation of the time duration limits for safe normothermic selective cerebral perfusion is required.