title: The effect of left ventricular pacing on transmural activation delay in myopathic human hearts.
abstract: Left ventricular (LV) epicardial pacing (LVEpiP) in human myopathic hearts does not decrease global epicardial activation delay compared with right ventricular (RV) endocardial pacing (RVEndoP); however, the effect on transmural activation delay has not been evaluated. To characterize the transmural electrical activation delay in human myopathic hearts during RVEndoP and LVEpiP compared with global epicardial activation delay.
  
  
  
  Explanted hearts from seven patients (5 male, 46 ± 10 years) undergoing cardiac transplantation were Langendorff-perfused and mapped using an epicardial sock electrode array (112 electrodes) and 25 transmural plunge needles (four electrodes, 2 mm spacing), for a total of 100 unipolar transmural electrodes. Electrograms were recorded during LVEpiP and RVEndoP, and epicardial (sock) and transmural (needle) activation times, along with patterns of activation, were compared. There was no difference between the global epicardial activation times (LVEpiP 147 ± 8 ms vs. RVEndoP 156 ± 17 ms, P = 0.46). The mean LV transmural activation time during LVEpiP was significantly shorter than that during RVEndoP (125 ± 44 vs. 172 ± 43 ms, P < 0.001). During LVEpiP, of the transmural layers endo-, mid-myocardium and epicardium, LV endocardial layer was often the earliest compared with other transmural layers.
  
  
  
  In myopathic human hearts, LVEpiP did not decrease global epicardial activation delays compared with RVEndoP. LV epicardial pacing led to early activation of the LV endocardium, revealing the importance of the LV endocardium even when pacing from the LV epicardium.
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Andreu
authors.initials: A
authors.lastname: Porta-Sánchez
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Paul
authors.initials: P
authors.lastname: Angaran
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Massé
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Krishnakumar
authors.initials: K
authors.lastname: Nair
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Talha
authors.initials: T
authors.lastname: Farid
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Karthikeyan
authors.initials: K
authors.lastname: Umapathy
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: John
authors.initials: J
authors.lastname: Asta
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Sigfus
authors.initials: S
authors.lastname: Gizurarson
authors.affiliation: The Hull Family Cardiac Fibrillation Management Laboratory, University Health Network, Toronto General Hospital, 150 Gerrard Street West, Gerrard Wing, 3-526, Toronto, ON, Canada M5G 2C4.
authors.forename: Kumaraswamy
authors.initials: K
authors.lastname: Nanthakumar
mesh_terms: D000200:Action Potentials; D000328:Adult; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D009202:Cardiomyopathies / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000503:physiopathology; D005260:Female; D006339:Heart Rate; D016027:Heart Transplantation; D006801:Humans; D000067268:Isolated Heart Preparation; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology*; D013997:Time Factors; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right; D055815:Young Adult