Hypoplastic Left Heart Syndrome With Low Birth Weight or Prematurity: What Is the Optimal Approach?

BACKGROUND

Hypoplastic left heart syndrome with low birth weight or prematurity comprises a high-risk population with no optimal treatment pathway. Using the Pediatric Health Information System, we compared management approaches across the United States.

METHODS

We analyzed neonates (≤30 days) with birth weight <2500 grams or gestational age <36 weeks between 2012 and 2021. Four strategies were identified: Norwood procedure, ductus arteriosus stent + pulmonary artery banding, pulmonary artery banding + prostaglandin infusion, or comfort care. Outcomes included hospital survival, discharge disposition, staged palliation completion, and 1-year transplant-free survival.

RESULTS

Of 383 infants identified, 36.4% (n = 134) received comfort care, 43.9% (n = 165) Norwood, 12.4% (n = 49) ductal stent + pulmonary artery bands, and 8.8% (n = 34) pulmonary artery bands + prostaglandins. Neonates receiving comfort care had the lowest gestational age (35 weeks; interquartile range [IQR], 31.5-37 weeks) and birth weight (2.0 kg; IQR, 1.5-2.3 kg); 24.6% (33 of 134) had chromosomal anomalies. Infants undergoing primary Norwood had the highest birth weight (2.4 kg; IQR, 2.2-2.5 kg) and gestational age (37 weeks; IQR, 35-38 weeks). Glenn palliation was performed in 66.1% (109 of 165) compared with ductal stent + pulmonary artery band in 18.4% (9 of 49) and pulmonary artery band + prostaglandins in 35.3% (12 of 34). Only 11.3% (6 of 53) born <2 kg survived to 1 year, all after Norwood. Primary Norwood yielded higher hospital and 1-year transplant-free survival than hybrid strategies.

CONCLUSIONS

Comfort care is routinely provided, particularly for infants with low birth weight, gestational age, or chromosomal anomalies. Primary Norwood offered the lowest hospital and 1-year mortality and highest palliation completion rates; birth weight was the most important factor determining 1-year survival.

Outcomes After Hybrid Palliation for Infants With Critical Left Heart Obstruction

BACKGROUND

Hybrid palliation (bilateral pulmonary artery banding with or without ductal stenting) is an initial management strategy for infants with critical left heart obstruction and serves as palliation until subsequent operations are pursued.

OBJECTIVES

This study sought to determine patient characteristics and factors associated with subsequent outcomes for infants who underwent hybrid palliation.

METHODS

From 2005 to 2019, 214 of 1,236 prospectively enrolled infants within the Congenital Heart Surgeons' Society's critical left heart obstruction cohort underwent hybrid palliation across 24 institutions. Multivariable hazard modeling with competing risk methodology was performed to determine risk and factors associated with outcomes of biventricular repair, Fontan procedure, transplantation, or death.

RESULTS

Preoperative comorbidities (eg, prematurity, low birth weight, genetic syndrome) were identified in 70% of infants (150 of 214). Median follow-up was 7 years, ranging up to 17 years. Overall 12-year survival was 55%. At 5 years after hybrid palliation, 9% had biventricular repair, 36% had Fontan procedure, 12% had transplantation, 35% died without surgical endpoints, and 8% were alive without an endpoint. Factors associated with transplantation were absence of ductal stent, older age, absent interatrial communication, smaller aortic root size, larger tricuspid valve area z-score, and larger left ventricular volume. Factors associated with death were low birth weight, concomitant genetic syndrome, cardiopulmonary bypass use during hybrid palliation, moderate to severe tricuspid valve regurgitation, and smaller ascending aortic size.

CONCLUSIONS

Mortality remains high after hybrid palliation for infants with critical left heart obstruction. Nonetheless, hybrid palliation may facilitate biventricular repair for some infants and for others may serve as stabilization for intended functional univentricular palliation or primary transplantation.

Norwood operation versus comprehensive stage II after bilateral pulmonary artery banding palliation for infants with critical left heart obstruction

OBJECTIVE

To determine patient characteristics and outcomes after Norwood versus comprehensive stage II (COMPSII) for infants with critical left heart obstruction who had prior hybrid palliation (bilateral pulmonary artery banding ± ductal stent).

METHODS

From 23 Congenital Heart Surgeons' Society institutions (2005-2020), 138 infants underwent hybrid palliation followed by either Norwood (n = 73, 53%) or COMPSII (n = 65). Baseline characteristics were compared between Norwood and COMPSII groups. Parametric hazard model with competing risk methodology was used to determine risk and factors associated with outcomes of Fontan, transplantation, or death.

RESULTS

Infants who underwent Norwood versus COMPSII had a higher prevalence of prematurity (26% vs 14%, P = .08), lower birth weight (median 2.8 vs 3.2 kg, P < .01) and less frequent ductal stenting (37% vs 99%; P < .01). Norwood was performed at a median age of 44 days and median weight of 3.5 kg, versus COMPSII at 162 days and 6.0 kg (both P < .01). Median follow-up was 6.5 years. At 5 years after Norwood and COMPSII, respectively; 50% versus 68% had Fontan (P = .16), 3% versus 5% had transplantation (P = .70), 40% versus 15% died (P = .10), and 7% versus 11% are alive without transition, respectively. For factors associated with either mortality or Fontan, only preoperative mechanical ventilation occurred more frequently in the Norwood group.

CONCLUSIONS

Higher prevalence of prematurity, lower birth weight, and other patient-related characteristics in the Norwood versus COMPSII groups may influence differences in outcomes that were not statistically significant for this limited risk-adjusted cohort. The clinical decision regarding Norwood versus COMPSII after initial hybrid palliation remains challenging.

The Evolution of Therapeutic Strategies: Niche Apportionment for Hybrid Palliation

Hybrid palliation, the concept to stabilize univentricular circulation with bilateral pulmonary artery banding and maintenance of ductal patency, has significantly widened the therapeutic spectrum for patients with single-ventricle malformations or borderline hypoplasia. The concept has already been a part of early attempts to improve outcome in hypoplastic left heart syndrome but has not attracted much attention initially. Technical refinement and expertise have led to results that ultimately allowed the palliative strategy to gain traction and to be selectively adopted. By now, we have gained almost 2 decades of experience, and as much as hybrid palliation has changed our approach to single-ventricle management, new strategies and indications have been formed by this experience. We therefore review concepts and patterns of use of hybrid palliation as well as benefits and challenges of the respective pathways to highlight the current status of the hybrid procedure.

ECMO: Incidence and Outcomes of Patients Undergoing the Hybrid Procedure

OBJECTIVE

To document the extracorporeal membrane oxygenation (ECMO) incidence and outcome in patients undergoing the hybrid procedure at an institution that routinely performs this procedure.

DESIGN

A retrospective chart review on all patients with single ventricle physiology that underwent the hybrid procedure between 7/2002 and 12/2014. Patients were excluded if they underwent the hybrid procedure after 60 days of birth or subsequently underwent a biventricular repair.

SETTING

A single center, tertiary pediatric hospital.

PATIENTS

One hundred eighty-one patients with single ventricle physiology that underwent the hybrid procedure between 7/2002 and 12/2014.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We studied a total of 181 patients (105 males: 76 females). Gestational age was 37.8 ± 2.0 weeks and birth weight was 3.0 ± 0.7 kg. Underlying diagnosis was hypoplastic left heart syndrome in 149 patients and other in 32 patients. Age at surgery was 7.8 ± 6.8 days and weight at surgery was 3.1 ± 0.6 kg. Two patients underwent ECMO support after the hybrid procedure. One patient had aortic atresia/mitral atresia and weighed 2.3 kg and the other patient had aortic atresia/mitral stenosis and weighed 2.1 kg at time of surgery. Both patients died. Incidence of ECMO support after hybrid procedure was 1.3% (2/149) for the hypoplastic left heart syndrome patients and 1.1% (2/181) for the entire cohort.

CONCLUSION

Mortality in patients who underwent ECMO after the hybrid procedure was higher than reported for the Norwood procedure, however, the incidence of ECMO after hybrid procedure was also significantly lower than reported for the Norwood procedure. Future studies are needed to determine how to improve outcomes in this complex patient population.

Current status of the hybrid approach for the treatment of hypoplastic left heart syndrome

The hybrid approach for hypoplastic left heart syndrome (HLHS), consisting of bilateral pulmonary artery banding and ductal stenting, has emerged as an alternative to the traditional Norwood approach. This approach defers open heart surgery to beyond the neonatal period, which is believed to reduce postoperative mortality and morbidity and improve neurological development as compared with the conventional approach. However, there have been no scientific studies supporting these hypotheses. Recently, there seems to be a tendency that many centers recommend the hybrid approach as an interim procedure to rescue preoperative high-risk patients. Currently, the decision to adopt the hybrid approach or the Norwood approach seemed to be based on the preference of congenital heart surgeons and cardiologists. Further investigation including a randomized multi-center study would allow a scientific decision as to which approach is more appropriate for the patient with HLHS.

Bilateral branch pulmonary artery banding as a bridge to decision/preoperative optimization of high-risk neonates with hypoplastic left heart syndrome

We present our experience with bilateral branch pulmonary artery banding as a bridge to decision/optimization of hemodynamics, followed by standard Norwood stage I palliation in very high-risk infants with hypoplastic left heart syndrome.

Individualized approach in the management of patients with hypoplastic left heart syndrome (HLHS)

Over the past decade new variations on the "classic" first stage palliation (the Norwood/BT shunt) for patients with Hypoplastic Left Heart Syndrome have emerged and been vetted by the medical community. A "one size fits all" approach may not be adequate anymore. In this review, the optimal indications for the various palliative options (Norwood/BT shunt, Norwood/RV-PA conduit, Hybrid Stage I with or without ductal stenting, heart transplantation) are reviewed from a standpoint of the initial anatomy and physiology of the patient, letting it guide clinical management. Current knowledge useful for decision-making is also reviewed as objectively as possible.