Does left ventricular size impact on intrinsic right ventricular function in hypoplastic left heart syndrome?

BACKGROUND: The size of the remnant left ventricle (LV) may influence right ventricular function and thus long-term outcome in palliated hypoplastic left heart syndrome (HLHS). We therefore sought to assess the impact of the size of the hypoplastic LV on intrinsic RV function in HLHS patients after Fontan surgery.
METHODS: Fifty-seven HLHS patients were studied 2.5 (range: 0.8-12.6) years after Fontan-type palliation with the pressure-volume conductance system. The patient cohort was divided into two groups according to the median LV area index (group 1: LV area index ≤ 1.33 cm(2)/m(2), n=29; group 2: LV area index>1.33 cm(2)/m(2), n=28).
RESULTS: The slopes of the end systolic elastance (Ees) and the preload recruitable stroke work relation (Mw) were not different between group 1 and 2 (Ees: 2.70 ± 1.92 vs. 3.68 ± 2.68 mmHg/ml; Mw: 52.75 ± 14.98 vs. 51.09 ± 16.63 mmHg x ml; P=NS for all). Furthermore, the systolic responses to dobutamine were not statistically different between groups. However, the slope of the end diastolic stiffness (Eed) was higher in group 2 and catecholaminergic stimulation resulted in a decrease in Eed in group 2 (group 1: 0.40 ± 0.26 vs. 0.52 ± 0.45; group 2: 0.68 ± 0.44 vs. 0.47 ± 0.38 mmHg/ml, P<0.01). Furthermore Eed was lowest in patients with mitral atresia/aortic atresia, the anatomic subgroup with the smallest LV remnant.
CONCLUSIONS: Intrinsic systolic RV function is not affected by the size of the hypoplastic LV in survivors of surgical palliation of HLHS. Diastolic stiffness, however, was higher in patients with a larger LV remnant.