title: Left ventricular rotational mechanics in Tanzanian children with sickle cell disease.
abstract: BACKGROUND
  Sickle cell disease (SCD) is a common inherited hemoglobinopathy. Adults with SCD manifest both systolic and diastolic cardiac dysfunction, though the age of onset of dysfunction has not been defined. Left ventricular (LV) rotational mechanics have not been studied in children with SCD. The aim of this study was to investigate whether cardiac rotational mechanics differed between children with SCD and age-matched controls.
  
  
  METHODS
  Basal and apical LV short-axis images were acquired prospectively in 213 patients with SCD (mean age, 14.1 ± 2.6 years) and 49 controls (mean age, 13.3 ± 2.8 years) from the Muhimbili Sickle Cohort in Dar es Salaam, Tanzania. The magnitude of basal and apical rotation, net twist angle, torsion, and untwist rate were obtained by two-dimensional speckle-tracking. The timing of events was normalized to aortic valve closure.
  
  
  RESULTS
  Mean basal rotation was significantly lower in patients with SCD compared with controls (P = .012), although no difference was observed in apical rotation (P = .37). No statistically significant differences in torsion or net twist angle were detected. Rotation rate at the apex (P = .001) and base (P = .0004) were significantly slower in subjects with SCD compared with controls. Mean peak untwisting rate was also significantly slower in patients with SCD (P = .006). No associations were found between hemoglobin concentration and apical rotation, basal rotation, net twist, and torsion.
  
  
  CONCLUSIONS
  This study demonstrates alterations in LV rotational mechanics in children with SCD, including lower basal rotation, peak differential twist, and untwist rate. These abnormalities denote subclinical changes in LV systolic and diastolic performance in children with SCD. Future work may reveal an association between rotational metrics and long-term patient outcomes.
authors.affiliation: University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado. Electronic address: michael.dimaria@childrenscolorado.org.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Di Maria
authors.affiliation: Division of Pediatric Cardiology, Children's Hospital & Medical Center, University of Nebraska Medical Center, Omaha, Nebraska.
authors.forename: Hao H
authors.initials: HH
authors.lastname: Hsu
authors.affiliation: Fort McMurray, Alberta, Canada.
authors.forename: Ghassan
authors.initials: G
authors.lastname: Al-Naami
authors.affiliation: University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Jeanine
authors.initials: J
authors.lastname: Gruenwald
authors.affiliation: University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: K Scott
authors.initials: KS
authors.lastname: Kirby
authors.affiliation: Department of Neurosciences, UCL Institute of Child Health, London, United Kingdom.
authors.forename: Fenella J
authors.initials: FJ
authors.lastname: Kirkham
authors.affiliation: Muhimbili Wellcome Programme, Muhimbili University of Health & Allied Sciences, Dar es Salaam, Tanzania; The London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Sharon E
authors.initials: SE
authors.lastname: Cox
authors.affiliation: University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, Colorado.
authors.forename: Adel K
authors.initials: AK
authors.lastname: Younoszai
mesh_terms: D000293:Adolescent; D000755:Anemia, Sickle Cell / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015984:Causality; D002648:Child; D015897:Comorbidity; D004452:Echocardiography / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D015203:Reproducibility of Results; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013636:Tanzania / Q000453:epidemiology; D014102:Torsion Abnormality / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D055815:Young Adult
keywords: Left ventricular torsion; Sickle cell disease