Right ventricular mechanical dyssynchrony in children with hypoplastic left heart syndrome

Background: Mechanical dyssynchrony predicts response to cardiac resynchronization therapy in adults with heart failure. Children with hypoplastic left heart syndrome (HLHS) are susceptible to right ventricular (RV) failure; however, mechanical dyssynchrony has not been studied in this population with newly available methodologies. We investigated RV mechanical dyssynchrony in children with HLHS using vector velocity imaging. Methods: We used vector velocity imaging to quantify the SD of time to peak velocity, strain, and strain rate among 6 RV segments to defme intraventricular RV synchrony in 16 children with HLHS and RV and left ventricular (LV) synchrony in 16 healthy age-matched control subjects. We further investigated relations between QRS duration and mechanical dyssynchrony and between mechanical dyssynchrony and systolic function. Results: Children with HLHS had significant RV mechanical dyssynchrony versus LV and RV control subjects (strain 37 +/- 35 vs 8 +/- 8 milliseconds, P = .003 [LV], 9 +/- 11 milliseconds, P = .005 [RV]; strain rate 31 +/- 37 vs 10 +/- 13 milliseconds, P = .04 [LV], 14 +/- 15 milliseconds, P = .09 [RV]). There was no significant relationship between QRS duration and mechanical dyssynchrony and no obvious relation between the degree of mechanical dyssynchrony and the RV fractional area of change. Conclusions: Children with HLHS have RV mechanical dyssynchrony unrelated to surface electrocardiographic QRS duration. This may contribute to RV dysfunction and may indicate the usefulness of cardiac resynchronization therapy in this population.