title: A novel multi-layer approach of measuring myocardial strain and torsion by 2D speckle tracking imaging in normal subjects and patients with heart diseases.
abstract: BACKGROUND
  This study adopted a new multi-layer approach of measuring myocardial deformation by two-dimensional (2D) speckle tracking imaging to examine whether a transmural gradient exists in normal subjects and cardiac diseases.
  
  
  METHODS
  Eighty patients were included with 20 in each group: (1) normal control; (2) acute coronary syndrome (ACS) with ejection fraction (EF) >45%; (3) right ventricular apical (RVA) pacing with EF>45%; (4) systolic heart failure (SHF) with EF<45%. Circumferential strain (ε-circum), torsion (Tor) and systolic dyssynchrony defined as the maximal difference in the time to peak circumferential strain were measured in the subendocardial and subepicardial myocardium layers (QLab 6.0, Philips).
  
  
  RESULTS
  In all the 4 groups, a subendocardial to subepicardial gradient was present in both ε-circum (-20.7 ± 7.6 vs. -14.9 ± 5.6%, p<0.001) and Tor (12.0 ± 6.0 vs. 9.3 ± 4.7°, p<0.05), with higher values in the subendocardial layer. However, it was significantly narrowed for ε-circum (2.7 ± 1.2%) and Tor (0.8 ± 0.9°) in SHF patients (all p ≤ 0.001 vs. other groups). On the contrary, systolic dyssynchrony measured in the 2 layers showed no difference (264 ± 107 vs. 273 ± 110 ms, p = NS) and a homogenous distribution in ε-circum was observed from basal to apical planes (-17.0 ± 6.8 vs. -18.1 ± 7.4 vs. -18.1 ± 7.8%, all p = NS).
  
  
  CONCLUSIONS
  A transmural gradient exists in circumferential strain and torsion, with higher values in the subendocardial layer. It might be reduced when systolic function is impaired. Therefore, the multi-layer approach of 2D speckle tracking imaging provides further information on assessment of myocardial diseases.
authors.affiliation: Li Ka Shing Institute of Health Sciences, Institute of Vascular Medicine and Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.forename: Yu-Jia
authors.initials: YJ
authors.lastname: Liang
authors.forename: Jun-Min
authors.initials: JM
authors.lastname: Xie
authors.forename: Yue-Yi
authors.initials: YY
authors.lastname: Wen
authors.forename: Gabriel Wai-Kwok
authors.initials: GW
authors.lastname: Yip
authors.forename: Yat-Yin
authors.initials: YY
authors.lastname: Lam
authors.forename: Joseph Yat-Sun
authors.initials: JY
authors.lastname: Chan
authors.forename: Jeffrey Wing-Hong
authors.initials: JW
authors.lastname: Fung
authors.forename: Cheuk-Man
authors.initials: CM
authors.lastname: Yu
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006331:Heart Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D054159:Torsion, Mechanical; D055815:Young Adult