title: Left ventricular myocardial response to exercise in children after heart transplant.
abstract: BACKGROUND
  Data on myocardial response to exercise after pediatric heart transplant (HTx) are limited. In this study we used semi-supine bicycle ergometry (SSCE) stress echocardiography to evaluate left ventricular (LV) systolic and diastolic reserve in pediatric HTx recipients.
  
  
  METHODS
  Forty-three HTx patients and 23 controls underwent stepwise SSCE stress echocardiography. Color tissue Doppler imaging (TDI) peak systolic (s') and early diastolic (e') velocities in the LV lateral wall and basal septum, and LV peak global longitudinal and circumferential strain were measured at rest and during different stages of exercise. LV myocardial acceleration during isovolumic contraction (IVA) was measured at incremental heart rates (HRs) to determine the force-frequency relationship (FFR).
  
  
  RESULTS
  At rest, compared with controls, HTx patients showed lower TDI velocities in the basal septum (s': 4.7 ± 1.1 vs 5.8 ± 0.8 cm/s, p = 0.002; e': 8.5 ± 2.1 vs 11.3 ± 1.7 cm/s, p < 0.001), whereas in the LV lateral wall only e' was lower (11.2 ± 2.6 vs 13.8 ± 2.3 cm/s, p < 0.001). LV IVA was not different between the groups (p = 0.10). LV peak global longitudinal strain was lower in HTx patients (18 ± 1.9% vs 20 ± 2.2%, p = 0.001), but peak circumferential strain was not different (p = 0.50). At peak, HR was lower in the HTx group (141 ± 12 vs 165 ± 15, p < 0.001), and all systolic and diastolic parameters, except circumferential strain, were lower in HTx recipients. When assessing the increase in TDI and strain values in relation to HR, the slopes were not significantly different between patients and controls.
  
  
  CONCLUSIONS
  Despite resting differences in myocardial functional parameters, pediatric HTx recipients have preserved LV diastolic and systolic myocardial reserve in response to exercise.
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cifra
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Andreea
authors.initials: A
authors.lastname: Dragulescu
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Henrik
authors.initials: H
authors.lastname: Brun
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Cameron
authors.initials: C
authors.lastname: Slorach
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Mark K
authors.initials: MK
authors.lastname: Friedberg
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Cedric
authors.initials: C
authors.lastname: Manlhiot
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Dipchand
authors.affiliation: Division of Cardiology, Labatt Family Heart Centre, The Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: luc.mertens@sickkids.ca.
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D003971:Diastole / Q000502:physiology*; D025401:Echocardiography, Stress; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D016027:Heart Transplantation; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D015588:Observer Variation; D012146:Rest / Q000502:physiology; D013599:Systole / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: children; exercise; heart transplantation; speckle tracking strain; stress imaging; tissue Doppler imaging