Original article
Right Ventricular Mechanical Dyssynchrony in Children with Hypoplastic Left Heart Syndrome

https://doi.org/10.1016/j.echo.2007.02.015Get rights and content

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 define 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.

Section snippets

Study Population

Patients between age 0 and 18 years with HLHS were identified from a pediatric echocardiography hospital database from echocardiograms performed between April 2005 and January 2006. Clinical data were obtained from the medical record. We included patients with a left ventricle (LV) that was inadequate to support the systemic circulation necessitating a Norwood type procedure in the neonatal period. Patients with HLHS were included at any stage of palliation: post-Norwood procedure (stage 1),

Results

Seventeen children with HLHS were identified. One patient was excluded because of external pacing, leaving 16 patients eligible for analysis. All had adequate echocardiographic images for VVI. Control subjects and children with HLHS were well matched for age (4.9 ± 4.6 vs 4.8 ± 4.4, not significant [NS]). Seven patients with HLHS had a RV-pulmonary artery conduit as part of their Norwood procedure, 7 patients had a Blalock-Taussig shunt as part of their Norwood procedure (if this information

Discussion

Intraventricular mechanical dyssynchrony is detrimental to ventricular function and predicts improved ventricular function in response to CRT.6 The results of this study show that mechanical dyssynchrony is prevalent in the systemic RV in HLHS. RV mechanical dyssynchrony may, therefore, constitute an additional detrimental factor in the development of RV dysfunction in HLHS in addition to other causes of RV dysfunction in HLHS. The presence of mechanical dyssynchrony in a patient with HLHS and

References (31)

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1

Dr Friedberg was supported by a Glaser Pediatric Research Network fellowship.

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