Surgeons face two choices for infants with critical left heart obstruction who have had prior hybrid palliation: a Norwood operation or a comprehensive stage II (COMPSII).

The critical left heart obstruction cohort of the multi-institutional Congenital Heart Surgeons’ Society looked at patient characteristics and outcomes for these two pathways.

The study, “Norwood Operation Versus Comprehensive Stage II After Bilateral Pulmonary Artery Banding Palliation for Infants With Critical Left Heart Obstruction,” was published recently in The Journal of Thoracic and Cardiovascular Surgery. The authors found differences in patient and clinical characteristics between the two groups but no statistically significant difference in outcomes for the risk-adjusted cohort.

“The clinical decision regarding Norwood versus COMPSII after initial hybrid palliation remains challenging,” according to the authors, including Bahaaldin Alsoufi, M.D., chief of pediatric cardiothoracic surgery at Norton Children’s Heart Institute, affiliated with the UofL School of Medicine. Norton Children’s Heart Institute was one of 23 Congenital Heart Surgeons’ Society institutions across the country participating in the study.

Among the 138 children in the cohort, those receiving the Norwood procedure were more often low birth weight and had a higher prevalence of prematurity and mechanical ventilation.

Another difference between the two groups: Children who underwent COMPSII were more likely to have ductal stenting and had shorter hospital stays.

In the cohort, 73 patients underwent the Norwood operation; 65 had a COMPSII. The procedures were performed after the infants had received bilateral pulmonary artery banding. Most of the children in the study were born with hypoplastic left heart syndrome.

Among the infants who underwent the Norwood procedure, surgery was performed at a median age of 44 days and a median weight of 3.5 kilograms. COMPSII was performed on children at a median age of 162 days and 6.0 kilograms. Median follow-up was 6.5 years.

At five years, 40% of the Norwood cohort had died, compared with 15% of the COMPSII group. Among the surviving children, 50% of the children who received the Norwood had the Fontan procedure versus 68% for the COMPSII group.

Differences in patient characteristics may have influenced patient outcomes, according to the study.

In factors associated with either mortality or Fontan, only preoperative mechanical ventilation occurred more frequently in the Norwood group, the study found.

According to the study, the decision to opt for one pathway versus the other is likely driven by the preference of the surgeon or institution, the reason for choosing hybrid palliation, and the infant’s clinical status.

With hypoplastic left heart syndrome, the most common single ventricle anomaly, the left ventricle, left mitral valve and ascending aorta are small.

With the Norwood procedure, the right ventricle is made systemic, so the pulmonary artery is connected to the aorta, while a Blalock-Taussig (BT) shunt or right ventricle to pulmonary artery Sano shunt provides pulmonary blood flow. A superior cavopulmonary connection (SCPC), also called a bidirectional Glenn, is performed at 4 or 5 months

A COMPSII operation includes a similar arch reconstruction, but the SCPC is performed at the same time.

Surviving children in both the Norwood or COMPSII groups receive a Fontan procedure at around age 3 years.