WASHINGTON — A new minimally invasive surgical technique could considerably improve the prognosis for infants born with hypoplastic left heart syndrome, Emile Bacha, M.D., said at a conference for science reporters sponsored by the American Medical Association.
Hyperplastic left heart syndrome (HLS), one of the most severe congenital heart defects, occurs in approximately 0.016%–0.036% of all live births in the United States, said Dr. Bacha, a pediatric cardiologic surgeon at the University of Chicago.
HLS is most often treated with a set of three extremely invasive, delicate open-heart surgical procedures aimed at providing unobstructed outflow to the heart via a single ventricle system and unobstructed pulmonary venous return, while shunting a portion of the blood away to feed the lungs and provide gas exchange.
Stage I, the Norwood operation, is performed within days of life. Stage II, the Glenn operation, follows at 6 months, while the stage III Fontan operation is done at 24 months.
Although 80%-90% of infants survive the Norwood stage I, about 10%-15% die before reaching the second procedure. Many infants who survive the entire series have below average IQ, abnormal neurologic development, and diminished quality of life.
Hybrid therapy, a combination of interventional cardiology and pediatric cardiac surgery techniques, replaces the traditional open-heart Norwood stage I operation with a palliative beating-heart procedure, he explained. Rather than cooling the body and putting the newborn on heart bypass for a lengthy period, the hybrid stage I is conducted in a specially outfitted catheterization laboratory that includes extra-corporeal circulation membrane oxygenation pump backup. (See illustration.)
Dr. Bacha and his colleague Ziyad M. Hijazi, M.D., have performed the procedure on 10 high-risk newborns (weight 2.2–3.3 kg) with HLS, of whom 6 also had aortic atresia, and 3 each had a major noncardiac anomaly, poor ventricular function, and/or weight less than 2.5 kg. Two were older than 30 days, one presented in shock, and one was born at less than 34 weeks' gestation. One infant died in the hospital following the procedure, resulting in the same hospital survival rate as the traditional Norwood stage I. Another died before reaching the second stage. Seven of the remaining eight have now undergone the Glenn stage II, of whom six have survived.
The Glenn and Fontan procedures are still necessary after hybrid stage I, but Dr. Bacha believes the elimination of one of three traumatic “pump runs” over the first 2 years of life and the postponement of the first beyond the neonatal period may reduce the neurologic complications often associated with bypass procedures.
The hybrid procedure itself and the length of hospital stay were considerably shorter than with the traditional Norwood procedure. One disadvantage of the hybrid technique is that the Glenn procedure is more complicated, since the aortic arch must be reconstructed while the previously implanted stent is removed.
“You're now doing the open-heart surgery on a 3− to 6-month-old, rather than a 5-day-old. … That is a huge difference in terms of sensitivity to trauma and brain maturity,” Dr. Bacha said. Several newer technologies, including therapeutic ultrasound and absorbable stents, will improve the feasibility of the procedure, he said.
EMILY BRANNAN, ILLUSTRATION