title: Left ventricular rotational mechanics before and after exercise in children.
abstract: BACKGROUND
  In children, there is limited information regarding the relative contribution of left ventricular (LV) apical and basal rotation to increase LV pump function with exercise. The aim of this study was to test the hypothesis that a progressive increase in LV pump function with exercise is related to increased LV apical and basal rotation.
  
  
  METHODS
  Forty-two subjects 12 to 18 years of age with normal cardiac structure and function were recruited prospectively and imaged at rest, and in 20 subjects, imaging was repeated after moderate exercise. Conventional measures of LV systolic and diastolic performance were evaluated. Left ventricular rotation, LV twist, rotational rate, and recoil and untwist rates were measured using two-dimensional speckle-tracking echocardiography. Torsion was calculated by normalizing LV twist to LV diastolic length. Twist displacement loops were constructed from data obtained at rest and after exercise.
  
  
  RESULTS
  Apical rotation increased significantly after exercise (7.33 ± 2.8° vs 11.6 ± 4.7°, P = .0004), but basal rotation did not (-4.85 ± 1.9 vs -6.46 ± 4.81, P = .21). Similarly, peak twist, torsion, and twist rate also increased significantly after exercise. In diastole, apical recoil rate and LV untwist rate also increased significantly with exercise. The slope of the systolic limb of the twist displacement loop and the area enclosed by the loop also increased significantly with exercise.
  
  
  CONCLUSIONS
  Increases in global LV pump function during exercise in children are associated with enhanced LV apical rotation but not LV basal rotation. In addition, unique changes were seen in twist displacement loops in children before and after exercise. These data may serve as a foundation for understanding future applications of LV rotational mechanics in disease states.
authors.affiliation: The Cardiac Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; Division of Pediatric Cardiology, The Perelman School of Medicine at The University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Di Maria
authors.affiliation: Division of Cardiology, Mount Sinai School of Medicine, New York, New York.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Caracciolo
authors.affiliation: Carleton University, Ottawa, Ontario, Canada.
authors.forename: Steven
authors.initials: S
authors.lastname: Prashker
authors.affiliation: Division of Cardiology, Mount Sinai School of Medicine, New York, New York.
authors.forename: Partho P
authors.initials: PP
authors.lastname: Sengupta
authors.affiliation: The Cardiac Center, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; Division of Pediatric Cardiology, The Perelman School of Medicine at The University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: banerjeea@email.chop.edu.
authors.forename: Anirban
authors.initials: A
authors.lastname: Banerjee
mesh_terms: D000293:Adolescent; D002648:Child; D004452:Echocardiography / Q000379:methods*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012399:Rotation; D013318:Stroke Volume / Q000502:physiology; D019415:Torque; D016277:Ventricular Function, Left / Q000502:physiology*
keywords: Exercise; Left ventricular mechanics; Torsion