Cardiac Function After Norwood and Hybrid Palliation in HLHS
Are there differences in ventricular function in patients after the hybrid procedure for hypoplastic left heart syndrome (HLHS) as compared with Norwood palliation?
A retrospective cohort study was performed at a single center. Echocardiography was obtained before stage I, before and after stage II, and before and after Fontan.
A total of 76 patients were studied, of which 42 underwent the Norwood procedure and 34 the hybrid procedure. Baseline characteristics were similar. Following the hybrid procedure, patients demonstrated a significant decrease in right ventricle (RV) fractional area change (FAC) between baseline and pre-stage II (36 ± 9% vs. 27 ± 6%; p < 0.01), while the Norwood patients remained stable (32 ± 10% vs. 32 ± 7%, p = 0.21). After stage II, the difference in FAC became insignificant (29 ± 7% for the Norwood patients vs. 25 ± 8% for the hybrid patients). Pre-Fontan, RV FAC was similar after Norwood and hybrid (34 ± 5% vs. 33 ± 6%), which remained unchanged after Fontan.
Patients after Norwood and hybrid procedures had equivalent indices of RV size, as well as systolic and diastolic function throughout all stages of palliation. Small differences in individual RV and tricuspid valve indices are more likely explained by differences in physiology or surgical timing, as compared with intrinsic differences in myocardial and valve function.
Proposed benefits of the hybrid procedure include relative hemodynamic stability after stage I, and prevention of brain and myocardial injury by avoiding the need for cardiopulmonary bypass and aortic arch reconstruction in the early neonatal period. This study demonstrated no difference in RV function around the time of Fontan for patients undergoing hybrid as compared with conventional surgical palliation for their initial procedure. This was a relatively select group of single-ventricle patients, as those with unbalanced atrioventricular septal defect and those selected for early heart transplant were excluded. This study suggests that we should not use the possibility of improved short- or long-term ventricular function as motivation for using the hybrid procedure. Individual center characteristics and outcomes and perhaps patient characteristics are most likely to inform a decision about the hybrid approach versus Norwood palliation. The survival rates in this study demonstrate the continued challenge of this patient group, with survival of 50% to stage III for patients initially palliated with the Norwood procedure and 44% for those initially palliated with the hybrid.
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