The impact of afterload reduction on the early postoperative course after the Norwood operation - a 12-year single-centre experience.

Objective: The objective of this study was to analyse the postoperative course and early outcome after the Norwood operation for patients with hypoplastic left heart syndrome. We particularly aimed to assess the impact of surgical and pharmacological modifications introduced.

Methods: Of 157 patients who underwent the Norwood operation between January 1996 and December 2007, postoperative intensive care data on haemodynamics, pharmacological support and ventilation were analysed from 146 patients (six patients died intra-operatively and data were incomplete in five). The cohort was divided into three groups depending on the surgical method and type of afterload reduction. Patients of group 1 (n=39, January 1996-December 1999) were operated with deep hypothermic circulatory arrest. In patients of group 2 (n=59, January 2000-June 2003) and group 3 (n=59, July 2003-December 2007) antegrade selective cerebral perfusion was used. Patients of groups 1 and 2 received sodium nitroprusside to reduce afterload; in group 3 phentolamine was used.

Results: There were no differences between the groups in terms of preoperative status and anatomy, except a higher incidence of prenatal diagnosis between groups 3 and 1. The duration and dosage of sodium nitroprusside administration were similar in groups 1 and 2. The median duration of afterload reduction was significantly longer in group 3 compared with both the other groups (72 h (range: 24-201 h) vs 48 h (range: 8-145 h) and 48 h (range: 4-173 h), respectively). The median ventilation times was shorter in group 2 compared with group 1 (61 h (range: 16-1191 h) vs 119 h (range: 26-648 h)). During the first 36 postoperative hours, the mean arterial blood pressure and coronary perfusion pressure were significantly lower in group 3 than in group 1 (50.7+/-4.8 and 28+/-3.7 mmHg vs 53.6+/-5.2 and 31.4+/-4.3 mmHg), but, in patients of group 3, the time period to consistently reach a mean arteriovenous oxygen difference below 5 ml dl(-1) was markedly shorter than in the other groups (group 3: 12h 4.90+/-1.97 ml dl(-1); group 1: 24h 4.53+/-2.25 ml dl(-1) and group 2: 24h 4.57+/-2.04 ml dl(-1)). Complication rates were similar between the groups. However, 30-day mortality decreased over the study period to an exponentially weighted moving average of 2.3%.

Conclusion: Adamant afterload reduction improves systemic blood flow early after the Norwood operation and may have contributed to the reduction in early postoperative mortality achieved over 12 years.