©2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.
Measures of Dyssynchrony in the Left Ventricle of Healthy Children and Young Patients with Dilated Cardiomyopathy
Vincent C Thomas, MD, Kristopher M Cumbermack, MD, Carey K Lamphier, RN, Christina R Phillips, RDCS, Derek A Fyfe, MD, PhD, Brandon K Fornwalt, MD, PhD
Brandon K Fornwalt, MD, PhD, University of Kentucky, 800 Rose Street, MN-150, Lexington, KY 40536, USA. Email: email@example.com.
Background—Doppler tissue imaging (DTI) may help identify children with dyssynchrony who could benefit from resynchronization therapy. However, few studies have quantified dyssynchrony measures in children, no study has investigated the relationship between age, heart rate and dyssynchrony measures in children, and no study has quantified cross-correlation delay in children. We hypothesized that measures of left ventricular dyssynchrony would correlate with age primarily due to correlation between heart rate and age, and that children with cardiomyopathy would have left ventricular dyssynchrony.
Methods—Sixty healthy children and 11 children with dilated cardiomyopathy were prospectively enrolled. Seven dyssynchrony measures were quantified: septal-lateral delay (SLD), peak velocity difference (MaxDiff), SD of times-to-peak in 12 segments in systole (Ts-SD) and diastole (Te-SD), and cross-correlation delay in systole (XCDsystole), diastole (XCDdiastole) and the whole-cycle (XCDwhole).
Results—The 7 dyssynchrony measures were either not correlated with age or only weakly correlated with age after correcting for heart rate using BazettŐs formula. SLD, MaxDiff and Ts-SD showed dyssynchrony in 57–85% of normals compared to 20% for XCDwhole and 3% for Te-SD. XCDsystole, XCDdiastole, XCDwhole, and Te-SD were elevated in children with dilated cardiomyopathy compared to controls.
Conclusion—Echocardiographic dyssynchrony measures should be corrected for heart rate using BazettŐs formula in children. Time-to-peak DTI dyssynchrony measures classify many healthy children as having an abnormality with the timing of left ventricular contraction, which suggests the methodology is not accurate in children. In preliminary studies, cross-correlation dyssynchrony measures show elevated systolic and diastolic measures of dyssynchrony in children with dilated cardiomyopathy compared to controls, which deserves further investigation to help identify children who may benefit from resynchronization therapy.