Relation between right ventricular enlargement, QRS duration, and right ventricular function in patients with tetralogy of Fallot and pulmonary regurgitation after surgical repair

Objective-In patients with repaired tetralogy of Fallot, to examine (1) a p ossible relation between right ventricular enlargement and QRS prolongation , and (2) the effect of right ventricular enlargement caused by pulmonary r egurgitation on the right ventricular ejection fraction, evaluated by three dimensional echocardiography, and global function, evaluated by the myocar dial performance index. Design and patients-40 patients with repaired tetralogy were studied. Right ventricular volumes were derived from three dimensional echocardiographic data after this method had been validated by comparison with magnetic reson ance imaging in 21 patients. Ejection fraction was calculated from end dias tolic and end systolic volumes. The Doppler derived myocardial performance index was measured in all patients. Measured data were correlated with QRS duration. Setting-Tertiary cardiac centre for congenital heart disease. Results-There was good agreement between three dimensional echocardiographi c and magnetic resonance assessment of right ventricular volumes and ejecti on fraction. The z score of the right ventricular end diastolic volume and ejection fraction of all patients was 1.35 and -4.15, respectively. Patient s with severe pulmonary regurgitation had a lower right ventricular ejectio n fraction (p < 0.01) and an increased myocardial performance index (p < 0. 01) compared with patients with mild to moderate pulmonary regurgitation. T he correlation between ejection fraction and right ventricular end diastoli c volume was r = -0.35 (p < 0.05). The mean (SD) QRS duration was 131.89 (2 5.69) ms, range 80-180 ms. The correlation between QRS duration and right v entricular end diastolic volume was r = 0.6 (p < 0.01). Conclusions-There is a correlation between the right ventricular size obtai ned by three dimensional echocardiography and QRS duration on the surface E GG, indicating mechanoelectrical interaction. The severity of pulmonary reg urgitation has a negative influence on right ventricular ejection fraction and combined systolic and diastolic global function, as assessed by myocard ial performance.