Right ventricular dysfunction and dyssynchrony after surgical repair of tetralogy of fallot: a three-dimensional and speckle tracking echocardiographic study

Background. Prolonged QRS duration and mechanic-electrical interaction are markers of increased sudden death risk in tetralogy of Fallot (TF). The combined effects of preoperative hypertrophy and hypoxia, possible intraoperative myocardial damage, type of reconstruction, and acquired postoperative lesions such as pulmonary regurgitation may result in impaired RV deformation. Recently speckle tracking echocardiography (STE) has been proposed to assess mechanical dyssynchrony in these patients but the role of electromechanical dysfunction is not completely clear. Methods. Fifteeen patients after TF repair (aged 17-51years) with dilated right ventricle, right bundle branch block (QRS 120ms), and NYHA class I or greater were studied with two-dimensional and three-dimensional echocardiography (3DE) and STE. Right ventricular volumes and right ventricular ejection fractions (3D-RVEF) were obtained. Right intraventricular dyssynchrony was determined as the difference between the longest and shortest electromechanical coupling times in the basal septal and lateral RV segments. Interventricular dyssynchrony was determined as the difference between electromechanical coupling times in the basal lateral LV segment and the most delayed RV segment. Fifteeen age-matched healthy subjects were selected as controls. Results. Right intraventricular dyssynchrony (76.223.8ms vs 12.79.1ms) and interventricular dyssynchrony (75.224.3ms vs 11.38.2ms) were shown in patients compared to normal controls. Right intraventricular dyssynchrony correlated with RV longitudinal strain, 3D RV end-systolic volume, and QRS duration. Interventricular dyssynchrony correlated with RV longitudinal strain , RV systolic pressure, 3D-RVEF, and QRS duration. Reduced RV strain, 3D-RVEF and prolonged QRS duration were the main determinant factors predicting dyssynchrony by multivariate analysis. On ROC curves RV strain and 3D-RVEF had optimal predictive accuracy of the NYHA functional class and a larger area under the receiver operating characteristic curve than the QRS duration. Conclusions. RV systolic dysfunction and dyssynchrony can be identified in patients with repaired TF by 3DE and STE. Dyssynchrony is associated with reduced 3D-RVEF and RV myocardial deformation.