Arterial elastance and its impact on intrinsic right ventricular function in palliated hypoplastic left heart...

Systemic right ventricular (RV) function is a major determinant of long-term outcome in patients with palliated hypoplastic left heart syndrome (HLHS). Abnormal elastic properties of the reconstructed aorta may negatively impact on ventricular function. We therefore aimed to assess arterial elastance and its relationship to systemic RV function in these patients.

Fifty-six HLHS patients (median age 5.4 years; range 2.9-14.2 years) were studied at a median of 2.6 years (range 0.8-12.7 years) after completion of the Fontan circulation with the pressure-volume conductance system.

Arterial elastance (Ea) was abnormally high and correlated inversely with RV ejection fraction (r=-0.42, P=0.001). However, end systolic elastance (Ees) - a load independent measure of intrinsic systolic ventricular function - and more so end diastolic stiffness (Eed) were positively correlated with Ea (Ees vs. Ea: r=0.44, P=0.001: Eed vs. Ea: r=0.62, P<0.0001). Patients who were treated for significant aortic arch obstruction after surgical palliation showed higher Ea and Eed even four years after successful treatment compared to the remainder of the group (Ea: 3.4 ± 1.2 vs. 2.8 ± 1.0 mmHg/ml, P=0.04 and Eed: 0.67 ± 0.44 vs. 0.45 ± 0.3 mmHg/ml, P=0.04).

Arterial elastance is abnormally high in palliated HLHS patients and negatively impacts on ejection fraction but not on intrinsic systolic RV function early after completion of the Fontan circulation. Increased arterial elastance, however, is associated with increased RV diastolic stiffness with potential adverse effects on long-term outcome. Furthermore, arterial elastance and diastolic stiffness are particularly high in patients who needed treatment for aortic arch obstruction.