Single ventricle systolic function and cardiopulmonary exercise performance in adult patients with Fontan circulation

We employed echocardiographic tissue characterization for the assessment of single ventricle systolic function and examined its relationship with cardiopulmonary exercise testing (CPET) performance in the Fontan circulation.

40 consecutive adult Fontan patients (16 female, 24 male; mean age 26.3 ± 5.9) were enrolled in our prospective cross-sectional study. All patients underwent echocardiographic assessment including tissue characterization and CPET within 3 days from each other.

LAPSE (lateral annular plane systolic excursion) was higher in patients with a dominant left ventricle compared to a dominant right ventricle (12.3 + -2.6 vs 9.8 + -1.1 mm, p = .008) and in patients with AP (right atrium-pulmonary artery) connection than with lateral tunnel or extracardiac conduits (13.9 ± 1.7 vs 11.3 ± 2.6 and 10.9 ± 2.2 mm, p = .014 and p = .014, respectively). Maximal oxygen pulse (O₂ pulse max) was significantly higher in patients with a dominant left or common ventricle compared to patients with a dominant right ventricle (10.3 and 12.0 vs 6.6 ml/beat, p = .002 and p = .032, respectively). There was a positive correlation between O₂ pulse max and LAPSE (r = 0.442, p = .009), atrioventricular valve annulus systolic velocity (S') (r = 0.606, p < .0001), lateral wall basal segment systolic velocity (bas vel s) (r = 0.469, p = .009) and lateral wall mid segment systolic velocity (mid vel s) (r = 0.452, p = .012). In the multivariable regression model, S' (r = 0.606, p < .0001) remained predictive of O₂ pulse max.

LAPSE and S' are suitable parameters for the assessment of systolic function in Fontan patients. Subclinical systolic dysfunction of longitudinal fibers is associated with worse CPET performance. O₂ pulse max seems to be the best parameter reflecting Fontan patients' physical performance.