title: Insights into dyssynchrony in hypoplastic left heart syndrome.
abstract: BACKGROUND
  Cardiac resynchronization therapy has been proposed for treatment of hypoplastic left heart syndrome (HLHS) patients with right ventricular (RV) failure. The role of dyssynchrony, however, is poorly understood in this population.
  
  
  OBJECTIVE
  The purpose of this study was to better understand the relationship between electrical and mechanical dyssynchrony in HLHS using 3-dimensional electrical mapping, tissue Doppler indices of wall motion, and vector velocity imaging.
  
  
  METHODS
  Eleven HLHS subjects with normal RV function and ten normal subjects (age 3-18 years) were studied. Electrical and mechanical activation times and dyssynchrony indices (electrical dyssynchrony index, mechanical dyssynchrony index) were calculated using 3-dimensional electrical mapping, tissue Doppler indices, and vector velocity imaging.
  
  
  RESULTS
  No differences in measures of electrical dyssynchrony were seen when comparing HLHS patients and normal patients (electrical activation time 63.3 ± 22.8 ms vs 56.2 ± 11.2 ms, P = .38; electrical dyssynchrony index 13.7 ± 6.3 ms vs 11.6 ± 3.0 ms, P = .34). However, measures of mechanical dyssynchrony were markedly abnormal in HLHS patients despite normal RV function (mechanical activation time 16 ± 11.3 ms vs 0.9±1.9 ms, P = .01; mechanical dyssynchrony index 7.5 ± 5.5 vs 0.4 ± 0.8, P<.01).
  
  
  CONCLUSIONS
  Patients with HLHS and preserved RV systolic function have normal electrical activation when compared to patients with normal right and left ventricles. In contrast, these patients demonstrate mechanical dyssynchrony compared to patients with normal right and left ventricles. This finding raises important questions about the indications for cardiac resynchronization therapy in this patient population.
authors.affiliation: Department of Pediatrics, Stanford University, Palo Alto, California, USA. sachie@stanford.edu
authors.forename: Kara S
authors.initials: KS
authors.lastname: Motonaga
authors.forename: Christina Y
authors.initials: CY
authors.lastname: Miyake
authors.forename: Rajesh
authors.initials: R
authors.lastname: Punn
authors.forename: David N
authors.initials: DN
authors.lastname: Rosenthal
authors.forename: Anne M
authors.initials: AM
authors.lastname: Dubin
mesh_terms: D000293:Adolescent; D018780:Body Surface Potential Mapping; D058406:Cardiac Resynchronization Therapy; D002648:Child; D002675:Child, Preschool; D015150:Echocardiography, Doppler; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D006801:Humans; D018636:Hypoplastic Left Heart Syndrome / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D007223:Infant; D008297:Male; D011446:Prospective Studies; D016896:Treatment Outcome; D018497:Ventricular Dysfunction, Right / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D016278:Ventricular Function, Right / Q000502:physiology*