Percentiles for left ventricular rotation: comparison of reference values to paediatric patients with pacemaker-induced dyssynchrony.

AIM Left ventricular rotation is an interesting mechanism to investigate patients with heart disease. In children, reference values have to be defined prior to assess pathology. METHODS AND RESULTS One hundred and seventy-four healthy individuals (0-20 years) were investigated by two-dimensional speckle tracking echocardiography, percentiles were created addressing the amount and time-to-peak values (TTP) of rotational parameters normalized to percentage of cardiac cycle (cc). Patients with right ventricular (RV) pacemaker stimulation were integrated into percentiles describing their rotational delay. Feasibility was 87.4% in healthy individuals (8.5 ± 6.2 years), 42 patients (13.0 ± 6.6 years, mean RV-stimulation time: 6.1 ± 4.3 years) were enrolled. Apical rotation (Rot(ap)) varied and was higher than basal rotation (Rot(bas)) throughout all ages. Peak torsion (Tor(max)) normalized to left ventricle (LV) length (Tor(maxi)) was elevated in early childhood and decreased until adulthood. TTP values revealed greater dispersion between apical and basal rotation at younger age and a decrease during maturation. Patients with RV pacing had decreased Tor(max) (10.0 ± 6.0 vs. 13.7 ± 6.6°, P < 0.05), Rot(ap) (6.7 ± 4.8 vs. 9.3 ± 5.7°, P < 0.05) and Rot(bas) (-3.3 ± 2.6 vs. -4.5 ± 2.7°, P < 0.05). Patients with impaired ejection fraction (EF) had abnormal delays between Rot(ap) and Rot(bas). CONCLUSIONS Percentile illustrations of LV rotation reveal a high amount and dispersion of Rot(ap) and Tor(maxi) in young children as well as a higher rotational delay compared with older ages. Abnormal delays in RV pacing are associated with reduced EF.