title: Coherent averaging improves the evaluation of left ventricular dyssynchrony by conductance catheter.
abstract: OBJECTIVE
  Coherent averaging is a technique to recover the response to repetitively applied stimuli when that response is embedded in random noise. We derived novel indices for left ventricular dyssynchrony estimation from volume-catheter signals using coherent averaging procedure: mechanical dyssynchrony (DYSCoh) internal flow fraction (IFFCoh) and mechanical dispersion (DISPCoh). The percentage power of non-repetitive components in the volume signals (ResTotAvg) was also estimated. The aims of the study were to evaluate the indices, characterizing repetitive and non-recurrent components of the conductance-volume signals, and to assess the ability of these indices to detect the changes in dyssynchrony induced by biventricular pacing (BIV).
  
  
  METHODS
  We compared the results obtained in 20 heart failure patients indicated to BIV (HF Group) during spontaneous conduction with the results from 12 patients with preserved ventricular function (non-HF Group), and with those obtained during BIV.
  
  
  RESULTS
  DISPCoh and ResTotAvg were significantly different in HF compared to non-HF group, and identified HF patients with high accuracy (area under curve at ROC analysis > 0.8). These indices also demonstrated significant differences after BIV (p = 0.047 and p = 0.037 respectively) and their baseline values correlated with the acute increase of stroke volume (r = 0.64 and r = 0.78, both with p < 0.005).
  
  
  CONCLUSIONS
  Coherent averaging-based indices permit independent quantification and differentiation of repetitive components of ventricular dyssynchrony from non-recurrent mechanical non-uniformities, which seem associated with HF and conduction disturbances. These indices identified HF patients with high accuracy, and were able to describe the reversal of dyssynchrony caused by BIV and to predict the acute hemodynamic improvement.
authors.affiliation: Istituto Auxologico Italiano, Ospedale S. Luca, Via Spagnoletto 3, 20149, Milan, Italy. perego@auxologico.it
authors.forename: Giovanni B
authors.initials: GB
authors.lastname: Perego
authors.forename: Sergio
authors.initials: S
authors.lastname: Valsecchi
authors.forename: Federica
authors.initials: F
authors.lastname: Censi
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Schreuder
authors.forename: Luigi
authors.initials: L
authors.lastname: Padeletti
mesh_terms: D000368:Aged; D000465:Algorithms; D002407:Catheterization, Swan-Ganz / Q000379:methods*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D010992:Plethysmography, Impedance / Q000379:methods*; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000175:diagnosis*