title: Variability of left ventricular electromechanical activation during right ventricular pacing: implications for the selection of the optimal pacing site.
abstract: BACKGROUND
  The right ventricular septum (RVS) and Hisian area (HA) are considered more "physiological" pacing sites than right ventricular apex (RVA). Studies comparing RVS to RVA sites have produced controversial results. There are no data about variability of electromechanical activation obtained by an approach using fluoroscopy and electrophysiological markers. This study compared the variability of left ventricular (LV) electromechanical activation in patients undergoing short-term RVA and RVS with that measured during HA pacing based on fluoroscopy and electrophysiological markers.
  
  
  METHODS
  Tissue Doppler echocardiography was performed in 142 patients before and after RVA (54), RVS (44), and HA (44) pacing. Electromechanical activation was assessed by: (1) electromechanical latency (EML)-interval between QRS onset and mechanical activation of basal LV; (2) intra-LV dyssynchrony (intra-LV)-interval between earliest to the latest LV basal motion. The intra- and interpatients variability among pacing groups were assessed.
  
  
  RESULTS
  Pacing from RVA showed longer EML and higher degree of intra-LV than RVS and HA pacing. RVA and RVS showed a higher variability than HA pacing with regard to intrapatient changes of EML (RVA vs RVS, P = 0.4; RVS vs HA, P = 0.01, RVA vs HA, P = 0.0002) and intra-LV (RVA vs RVS, P = 0.2; RVS vs HA, P = 0.04; RVA vs HA, P = 0.005). Similar results were found in interpatients variability from paced-values.
  
  
  CONCLUSIONS
  RVA and RVS pacing produce a variable effect on LV electromechanical activation that is significantly more pronounced than HA pacing. A pacing site such as HA selected by fluoroscopic and electrophysiological markers maintains baseline and homogeneous LV activation pattern.
authors.affiliation: Department of Cardiology, Rovigo General Hospital, Rovigo, Italy. gian.past@libero.it
authors.forename: Gianni
authors.initials: G
authors.lastname: Pastore
authors.forename: Francesco
authors.initials: F
authors.lastname: Zanon
authors.forename: Franco
authors.initials: F
authors.lastname: Noventa
authors.forename: Enrico
authors.initials: E
authors.lastname: Baracca
authors.forename: Silvio
authors.initials: S
authors.lastname: Aggio
authors.forename: Giorgio
authors.initials: G
authors.lastname: Corbucci
authors.forename: Roberto
authors.initials: R
authors.lastname: Cazzin
authors.forename: Loris
authors.initials: L
authors.lastname: Roncon
authors.forename: Serge S
authors.initials: SS
authors.lastname: Barold
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000503:physiopathology* / Q000628:therapy*; D002036:Bundle of His / Q000502:physiology*; D002304:Cardiac Pacing, Artificial; D018619:Echocardiography, Doppler, Pulsed; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D016276:Ventricular Function; D054088:Ventricular Septum / Q000502:physiology*