title: Effect of left ventricular pacing mode and site on hemodynamic, torsional and strain indices.
abstract: BACKGROUND
  Several reports have indicated that left ventricular (LV) lead placement at an optimal pacing site is an important determinant of short- and long-term outcome. This study investigated the effect of pacing mode (atrioventricular [AV] or ventricular) and site (LV apical or lateral) outside the ischemic region on the LV hemodynamic, torsional and strain indices in the ischemic myocardium.
  
  
  METHODS
  Experiments were conducted in anesthetized open-chest pigs (n = 15) 30 min after LAD ligation to investigate the hemodynamic effects of temporary epicardial AV and ventricular LV pacing at the LV apical (outside the ischemic region) or lateral wall. LV hemodynamic data were recorded (ejection fraction, stroke volume, dP/dtmax, systolic pressure, cardiac output and e/e΄ ratio) and torsional (twist, rotation), as well as deformation (radial and circumferential strain), indices of LV function were assessed using two-dimensional speckle tracking imaging.
  
  
  RESULTS
  The LV function was highly dependent on the pacing mode and site. LV dP/dtmax, systolic pressure and twist decreased significantly during LV pacing in comparison to sinus rhythm (p = 0.004, p<0.001, p = 0.002, respectively). Torsion in sinus rhythm decreased significantly during AV-pacing at the lateral wall (0.11±0.04°/mm vs. 0.06±0.02°/mm, p = 0.005) but did not change significantly during AV-pacing at the apex (0.07±0.05°/mm).
  
  
  CONCLUSIONS
  LV pacing at the apical or lateral wall, in the ischemic myocardium, leads to a suboptimal response in comparison to sinus rhythm. LV pacing at the apex outside the ischemic area exhibits a better response than pacing at the lateral wall, possibly because pacing from this site leads to a more physiological propagation of electrical conduction.
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece. Electronic address: stouman@otenet.gr.
authors.forename: Savvas
authors.initials: S
authors.lastname: Toumanidis
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Anna
authors.initials: A
authors.lastname: Kaladaridou
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Bramos
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Elias
authors.initials: E
authors.lastname: Skaltsiotes
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: John
authors.initials: J
authors.lastname: Agrios
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Georgiopoulos
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Anna
authors.initials: A
authors.lastname: Antoniou
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Pamboucas
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Elektra
authors.initials: E
authors.lastname: Papadopoulou
authors.affiliation: Department of Clinical Therapeutics, Medical School, National and Kapodistrian University of Athens, "Alexandra" Hospital, Athens, Greece.
authors.forename: Spyridon
authors.initials: S
authors.lastname: Moulopoulos
mesh_terms: D000818:Animals; D002304:Cardiac Pacing, Artificial / Q000379:methods* / Q000662:veterinary; D004195:Disease Models, Animal; D004452:Echocardiography; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006439:Hemodynamics; D006801:Humans; D008297:Male; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D013552:Swine
keywords: myocardial infarction; rotation; speckle tracking echocardiography; strain; twist