title: Quantification of left ventricular asynchrony throughout the whole cardiac cycle with a computed algorithm: application for optimizing resynchronization therapy.
abstract: BACKGROUND
  Measurement of left ventricular (LV) asynchrony is usually determined on single time points from spectral tissue Doppler imaging (TDI) scans that are frequently difficult to identify or not representative of the whole cardiac cycle. Our aim was to validate a new asynchrony index that evaluates the motion of the LV walls throughout the whole cardiac cycle.
  
  
  RESULTS
  Ten healthy volunteers and 50 patients undergoing cardiac resynchronization therapy (CRT) were studied with TDI. Wall displacement tracings from the septal and lateral LV walls were analyzed. Cross-correlation was calculated and 2 indices were obtained to assess LV asynchrony: the time delay and the superposition index (SI) between wall displacements. These results were compared between healthy volunteers and CRT patients, and between responders and nonresponders to CRT. Also, the optimal interventricular (VV) interval was based upon the best matching level. Volunteers showed lower asynchrony indices (83 +/- 2% SI, 17 +/- 8 ms time delay) as compared with CRT patients (63 +/- 15% SI, 73 +/- 60 ms time delay, P < 0.05). Responders also had more LV dyssynchrony than nonresponders (58 +/- 15% SI and 92 +/- 66 ms vs 68 +/- 12% and 48 +/- 34 ms, P < 0.05). The optimum VV interval selected by the computed algorithm showed an excellent concordance (Kappa = 0.90, P < 0.05) with that determined by other validated methods for optimizing the programming of CRT devices.
  
  
  CONCLUSIONS
  This approach allows measurement of LV intraventricular asynchrony throughout the cardiac cycle, being useful to determine the optimum VV interval and to select candidates for CRT.
authors: Thorax Institute, Hospital Clínic, University of Barcelona, Barcelona 08036, Spain.
authors: E
authors: E
authors: Silva
authors: M
authors: M
authors: Sitges
authors: L
authors: L
authors: Mont
authors: V
authors: V
authors: Delgado
authors: D
authors: D
authors: Tamborero
authors: B
authors: B
authors: Vidal
authors: M
authors: M
authors: Godoy
authors: S
authors: S
authors: Poyatos
authors: C
authors: C
authors: Pare
authors: M
authors: M
authors: Azqueta
authors: J
authors: J
authors: Brugada
mesh_terms: D000465:Algorithms; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013813:Therapy, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000517:prevention & control*