Transplant-Free Survival Among Children With Hypoplastic Left Heart Syndrome Undergoing Hybrid Palliation

As one of the few teams in the world almost exclusively performing hybrid palliation surgery for babies with hypoplastic left heart syndrome (HLHS) and related congenital heart defects, the cardiac surgery group at Nationwide Children’s Hospital has performed a large number of these alternative procedures since 2002. Their latest research suggests the team’s efforts have not been in vain, with 18 years of data suggesting transplant-free survival at age 15 is at least 44%.

Hybrid palliation surgery aims to address left-ventricle defects of the heart with a surgical approach that delays riskier types of interventions — conducted in the first surgery for the traditional operation called the Norwood procedure — until babies are older. The hybrid approach also reduces the amount of time children spend under cardiopulmonary bypass, which theoretically may offer some protection against a common problem (and lasting risk factor) after the Norwood procedure, called tricuspid regurgitation (TR).  Function of the heart’s right ventricle (RV) is another known factor influencing long-term health of children undergoing surgery for HLHS.

To better gauge the long-term success of hybrid palliation, clinician-researchers at Nationwide Children’s evaluated longitudinal data on 203 patients treated with at least the first stage of the hybrid procedure from 2002-2018. Echocardiography was used to evaluate TR and RV function at up to six points in time per child; follow-up surgeries (including type), death, transplant and other factors were also recorded.

“We found that RV function is the single biggest predictor of long-term outcomes. Consistent with the Norwood procedure, children with moderate or severe TR and/or significant RV dysfunction have higher mortality, but only in the first year of life,” says Sergio Carrillo, MD, a cardiothoracic surgeon at Nationwide Children’s and lead author on the study, published in the World Journal for Pediatric and Congenital Heart Surgery.

After age 1, TR and RV dysfunction may not play a significant role in survival. Most patients remained free of TR and RV dysfunction (83.33% and 91.66%, respectively) throughout the study, and transplant-free survival was 44.83% by the age of 15 (Norwood studies report a rate of about 39%).

Tricuspid valvuloplasty, an operation done to address serious TR, occurred in just under 5% of the hybrid palliation patients — compared to rates in the literature approaching five times that for children with traditional surgery for HLHS — and did not carry an increased risk in mortality.

In addition, Nationwide Children’s implemented comprehensive patient follow-up procedures and a formal interdisciplinary team approach to HLHS patient management in 2014. Although formal pre- and post-implementation studies are still underway, preliminary data found a reduction in interstage mortality and serious TR and/or RV dysfunction of about 50% each.

“This is just a single-center experience and the patients were nonrandomized, but these results suggest that the hybrid palliation approach may be noninferior or equal to Norwood for children with HLHS long-term,” says Dr. Carrillo of the procedure developed in part by Mark Galantowicz, MD, chief of cardiothoracic surgery at Nationwide Children’s. “Of course, we feel strongly that it’s at least equal, and sometimes even better. Our team has learned a lot through the years, perfected the art of surgery but also the art of managing these patients before and after, to help reach those outcomes.”

Reference:

Carrillo SA, Texter KM, Phelps C, Tan Y, McConnell PI, Galantowicz M. Tricuspid Valve and Right Ventricular Function Throughout the Hybrid Palliation Strategy for Hypoplastic Left Heart Syndrome and Variants. World Journal for Pediatric and Congenital Heart Surgery. 2020;2150135120947692. Epub ahead of print.

Image credit: Nationwide Children’s