Hybrid option ‘reasonable’ for HLHS?

Key clinical point: A hybrid operation for hypoplastic left heart syndrome (HLHS) and variants in neonates is emerging as an alternative to the Norwood palliation.

Major finding: At 10 years, the probability of survival with the hybrid procedure was 77.8%. Low body weight (less than 2.5 kg) and aortic atresia had no significant impact on survival.

Data source: Retrospective study of 182 patients who had the hybrid procedure at a single center between June 1998 and February 2015.

Disclosures: The study investigators had no relationships to disclose.

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Avoiding drawbacks of Norwood palliation

The study by Dr. Yerebakan and colleagues is one of the largest single-center series of patients with HLHS who routinely undergo a hybrid palliation to date, and while the study is open to criticisms, “the authors should be applauded,” Dr. Ralph S. Mosca of New York University said in his invited commentary (J Thorac Cardiovasc Surg. 2016;151:1123-25).

Among the criticisms Dr. Mosca mentioned are that the hybrid approach requires a more extensive stage II reconstruction, “often further complicated by the presence of significant branch PA stenosis and a difficult aortic arch reconstruction”; that there is “appreciable” interstage mortality at 12.2%; and that there is an absence of data on renal or respiratory insufficiency, infection rates, and neurologic outcomes.

Dr. Mosca cited the cause for applause, however: “Through their persistence and collective experience, [the authors] have achieved commendable results in this difficult patient population.”

Yet, Dr. Mosca also noted a number of “potential problems” with the hybrid approach: bilateral banding of the pulmonary artery is a “crude procedure”; arterial duct stenting can lead to retrograde aortic arch reduction; and the interstage mortality “remains significant.”

Results of the hybrid and Norwood procedures are “strikingly similar,” Dr. Mosca said. While the hybrid approach may lower neonatal mortality, it may also carry longer-term consequences “predicated upon the need to closely observe and intervene,” he said. Clinicians need more information on hybrid outcomes, but in time it will likely take its place as an option for HLHS alongside the Norwood procedure, Dr. Mosca said.




Although the classic Norwood palliation for infants with hypoplastic left heart syndrome (HLHS) has been well established, the procedure has had its drawbacks, namely the need for cardiopulmonary bypass with hypothermia and a because it rules out biventricular correction months later. A hybrid procedure avoids the need for bypass and accommodates short-term biventricular correction, but it has lacked strong evidence.

Researchers from Justus-Liebig University Giessen, Germany, reported on 182 patients with HLHS who had the three-stage Giessen hybrid procedure, noting 10-year survival of almost 80% with almost a third of patients requiring no artery intervention in that time (J Thorac Cardiovasc Surg. 2016 April;151:1112-23).

“In view of the early results and long-term outcome after Giessen hybrid palliation, the hybrid approach has become a reasonable alternative to the conventional strategy to treat neonates with HLHS and variants,” wrote Dr. Can Yerebakan and colleagues. “Further refinements are warranted to decrease patient morbidity.”

The Giessen hybrid procedure uses a technique to control pulmonary blood flow that is different from the Norwood procedure. The hybrid approach involves stenting of the arterial duct or prostaglandin therapy to maintain systemic perfusion combined with off-pump bilateral banding of the pulmonary arteries (bPAB) in the neonatal period. The Giessen hybrid operation defers the Norwood-type palliation using cardiopulmonary bypass that involves an aortic arch reconstruction, including a superior cavopulmonary connection or a biventricular correction, if indicated, until the infant is 4-8 months of age.

“In recent years, hybrid treatment has moved from a myth to an alternative modality in a growing number of institutions globally,” Dr. Yerebakan and colleagues said. The hybrid procedure has been used in high-risk patients. One report claimed higher morbidity in the hybrid procedure due to bPAB (Ann Thorac Surg. 2013;96:1382-8). Another study raised concerns about an adequate pulmonary artery rehabilitation at the time of the Fontan operation, the third stage in the hybrid strategy (J Thorac Cardiovasc Surg. 2014;147:706-12).

But with the hybrid approach, patients retain the potential to receive a biventricular correction up to 8 months later without compromising survival, “postponing an immediate definitive decision in the newborn period in comparison with the classic Norwood palliation,” Dr. Yerebakan and coauthors noted.

The doctors at the Pediatric Heart Center Giessen treat all types and variants of HLHS with the modified Giessen hybrid strategy. Between 1998 and 2015, 182 patients with HLHS had the Giessen hybrid stage I operation, including 126 patients who received univentricular palliation or a heart transplant. The median age of stage I recipients was 6 days, and median weight 3.2 kg. The stage II operation was performed at 4.5 months, with a range of 2.9 to 39.5 months, and Fontan completion was established at 33.7 months, with a range of 21 to 108 months.

Median follow-up after the stage I procedure was 4.6 years, and the death rate was 2.5%. After stage II, mortality was 4.9%; no deaths were reported after Fontan completion. Body weight less than 2.5 kg and aortic atresia had no significant effect on survival. Mortality rates were 8.9% between stages I and II and 5.3% between stage II and Fontan completion. “Cumulative interstage mortality was 14.2%,” Dr. Yerebakan and colleagues noted. “At 10 years, the probability of survival is 77.8%.”

Also at 10 years, 32.2% of patients were free from further pulmonary artery intervention, and 16.7% needed aortic arch reconstruction. Two patients required reoperations for aortic arch reconstruction.

Dr. Yerebakan and colleagues suggested several steps to improve outcomes with the hybrid approach: “intense collaboration” with anesthesiology and pediatric cardiology during and after the procedure to risk stratify individual patients; implementation of standards for management of all stages, including out-of-hospital care, in all departments that participate in a case; and liberalized indications for use of MRI before the stage II and Fontan completion.

Among the limitations of the study the authors noted were its retrospective nature and a median follow-up of only 5 years when the center has some cases with up to 15 years of follow-up. But Dr. Yerebakan and coauthors said they could not determine if the patients benefit from the hybrid treatment in the long-term.

The researchers had no disclosures.

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