Mechanical dyssynchrony in children with systolic dysfunction secondary to cardiomyopathy: A Doppler tissue and vector velocity imaging study

Objective. Mechanical dyssynchrony is common in adults with heart failure and its presence predicts response to cardiac resynchronization therapy. However, mechanical dyssynchrony and its quantification by echocardiography have not been extensively studied in children with cardiomyopathy. We investigated mechanical dyssynchrony in children with systolic dysfunction secondary to cardiomyopathy using Doppler tissue imaging (DTI) and vector velocity imaging (VVI). Methods: We used DTI and VVI to quantify mechanical dyssynchrony in 22 children with systolic dysfunction secondary to cardioinyopathy and in 25 healthy control subjects. We analyzed DTI results corrected for cardiac dimensions and evaluated correlation between electrical and mechanical dyssynchrony and between mechanical dyssynchrony and systolic function. Results. DTI and VVI revealed significant mechanical dyssynchrony among children with cardiomyopathy. Intraventricular and interventricular delays as defined by DTI and the SD of time to peak velocity, strain, and strain rate as defined by VVI were 2 to 3 times higher in patients with cardiomyopathy as compared with control subjects. There was no significant relationship between electrical and mechanical dyssynchrony. Conclusions. Children with systolic dysfunction secondary to cardiomyopathy have mechanical dyssynchrony, unrelated to electrical dyssynchrony, which can be measured by recent echocardiographic techniques including DTI and VVI. Children with cardiomyopathy and mechanical dyssynchrony are potentail candidates for cardiac resynchronization therapy.