Ventricular Twisting and Dyssynchrony in Children with Single Left Ventricle Using Three-Dimensional Speckle Tracking Imaging after the Fontan Operation

Abstract

Background: The importance of left ventricular (LV) twisting has been recognized in various types of heart disease, but no studies have investigated twisting of functional single ventricle using echocardiography. This study aimed to evaluate LV twisting and dyssynchrony of children with single left ventricle (SLV) after the Fontan operation and explore the relationship between twisting motion and ventricular contractility using three-dimensional speckle tracking imaging (3DSTI).

Methods: Thirty-five children with SLV and 35 healthy children (controls) were enrolled. The patients were divided into wide and narrow QRS groups according to the QRS interval. Atrioventricular valve inflow velocity and tissue Doppler imaging velocity were obtained, and the Tei index was calculated. Apical rotation, basal rotation, twist, torsion, time to peak apical rotation, time to peak basal rotation, time to peak twist, apical-basal rotation delay, and the systolic dyssynchrony index (SDI) were measured by 3DSTI.

Results: Patients with SLV had significantly lower apical rotation (2.50 ± 2.25° vs. 4.85 ± 2.68°, P < 0.001), basal rotation (-3.46 ± 3.11° vs. -7.76 ± 2.11°, P < 0.001), twist (5.15 ± 4.75° vs. 12.19 ± 3.65°, P < 0.001), and torsion (1.04 ± 0.99°/cm vs. 2.37 ± 0.77°/cm, P < 0.001) compared to controls. Time to peak basal rotation, apical-basal rotation delay, and time to peak twist were significantly longer in patients. Apical rotation was significantly lower in the wide QRS group but similar in the narrow QRS group as compared to controls. Time to peak twist and apical-basal delay were significantly longer in the wide QRS group in contrast to the similar time in the narrow QRS group compared with controls. Among these twisting parameters, twist and torsion were most significantly correlated with left ventricular ejection fraction (LVEF), the Tei index, and SDI. Twist and age were significantly correlated.

Conclusion: Twisting is reduced in children with SLV after the Fontan operation. Torsion is a good indicator of LV global function because of good reproducibility and its lack of association with age.

Keywords: single left ventricle; systolic dyssynchrony index; three-dimensional speckle tracking imaging; torsion; twist.