Ventriculoarterial coupling in palliated hypoplastic left heart syndrome: Noninvasive assessment of the effects of surgical arch reconstruction and shunt type

Objective: To assess the coupling efficiency in hypoplastic left heart syndrome, considering the effect of surgical arch reconstruction and the shunt type received during the Norwood procedure. Methods: Ventriculoarterial coupling was assessed before Fontan completion in 32 patients with hypoplastic left heart syndrome (19 modified Blalock-Taussig and 13 Sano shunts at stage 1). Cardiovascular magnetic resonance data were analyzed, deriving functional parameters and 3-dimensional volumes. Dimensional indexes were computed from 3-dimensional data sets as the area ratio of the isthmus to the descending aorta (R-isthmus) and the isthmus to surgically enlarged transverse arch (R-arch). Wave intensity was calculated from cardiac magnetic resonance, using the peaks of the forward compression and expansion waves in early and late systole as surrogate indicators of ventriculoarterial coupling. Results: Aortic distensibility (3.6 +/- 2.73 10(-3) 1/mm Hg) was not associated with the time elapsed from stage 1 palliation (P = .94), suggesting an early loss of elasticity that did not progress thereafter. R-isthmus was 1.0 +/- 0.4, and R-arch was 0.3 +/- 0.1, indicating the dilated reconstructed arch was themain anatomic feature. The forward compression wave correlated significantly with R-arch (R-2 = 0.23, P = .006) but not with R-isthmus (R-2 < 0.01, P = .63). Patients with a reduced ejection fraction exhibited a larger ventricular mass (R-2 = 0.28, P = .003). The Sano shunt patients had a lower ejection fraction (51% +/- 6% vs 57% +/- 6%, P = .02); however, neither the forward compression nor expansion wave varied significantly between shunt type or the other functional parameters. Conclusions: Ventriculoarterial coupling in operated hypoplastic left heart syndromewas affected by aortic arch size mismatch but not by the type of shunt placed at theNorwood operation.