In order to survive, children born with hypo plastic left heart syndrome (HLHS) need to undergo reconstructive surgery to restore blood circulation. The most commonly prescribed procedure is the 3-stage Norwood, which uses a venous shunt, but a recent study suggests an alternative procedure that uses an arterial shunt may offer more benefits in reestablishing pulmonary blood supply. The study, titled “Second stage after initial hybrid palliation for hypo plastic left heart syndrome: Arterial or venous shunt?” is published in The Journal of Thoracic and Cardiovascular Surgery.
HLHS affects nearly 1,000 infants in the United States, causing the left side of the newborn’s heart to be underdeveloped, severely compromising systemic blood flow. The disorder can manifest as late as days after the baby is born, when the heart’s ductus arteriosus begins to close. While this is a natural phenomenon for all babies, those with HLHS can die from it. The three-stage Norwood procedure occurs at different times of the infant’s development, with Norwood Stage I typically performed soon after birth, Norwood II (commonly referred to as a bidirectional Glenn – or cavopulmonary – shunt) between 4 and 6 months of age, and the final surgery, termed a modified Fontan Procedure, between 2 and 5 years of age. This 3-stage procedure has achieved 30-day survival rates of over 90%, however some surgeons believe these numbers can still be improved, especially for higher risk infants.
“Hybrid palliation was initially thought to be a therapy that would eventually supplant standard Norwood palliation because of its technical simplicity, its avoidance of cardiopulmonary bypass (open heart surgery) and prolonged perioperative recovery in the neonatal period, and an intuitive notion that it would be associated with improved neurodevelopmental outcomes,” commented David M. Overman, MD, Chief of the Division of Cardiovascular Surgery at the Children’s Hospitals and Clinics of Minnesota (Minneapolis) in an accompanying editorial.
“In our center, the hybrid procedure is reserved for higher-risk, more complex, and unstable patients in whom a traditional Norwood procedure would carry an unacceptably high risk,” explained lead investigator Mohamed S. Nassar, PhD, FRCS, of the departments of Paediatric Cardiology and Cardiac Surgery, Evelina London Children’s Hospital, Guy’s and St. Thomas’ NHS Foundation Trust (London).
Both types of reconstructive procedures were being offered at the same institution, which gave the researchers a chance to conduct a retrospective analysis of these patients’ cases to determine whether one procedure produced better outcomes than the other. Nassar listed 17 HLHS patients that received the arterial shunt, and 26 who received a venous shunt. The scientists’ prediction of the latter group showing better pulmonary arterial growth was confirmed.
The two surgeries vary in terms of their pros and cons, however. While surgical time is shorter in receiving an artierial shunt, these patients tended to exhibit a greater need for delayed sternal closure. The researchers noted that mechanical ventilation and need for intensive care were shorter in patients who received the venous shunt, and that those who received arterial shunts had significantly higher oxygen saturations at discharge.
Dr. Overman clarified that even though hybrid surgery is normally recommended for a small subset of HLHS patients, he recognizes the increased need for this procedure in higher-risk patients. “The impact and advisability of that particular approach, while intuitively resonant, is still an open question. The arterial shunt at Stage II is yet another twist in the evolving story of hybrid therapy for HLHS.”