title: The effects of anodal stimulation on electrocardiogram, left ventricular dyssynchrony, and acute haemodynamics in patients with biventricular pacemakers.
abstract: OBJECTIVE
  Anodal stimulation (ANS) is a recognized phenomenon among patients with cardiac resynchronization therapy (CRT); this is noted during left ventricular (LV) pacing by the LV tip to right ventricular (RV) ring configuration. Its incidence varies according to the implanted hardware. We aim at evaluating the incidence of ANS and its acute haemodynamic effects among CRT patients.
  
  
  RESULTS
  We screened all our patients who previously had an implanted CRT-P/D devices for ANS. After excluding all non-eligible devices, the initial screening was done by evaluating the programmer electrocardiogram (ECG) during device interrogation while pacing LV only from LV tip to RV ring. Those with ANS underwent screening by 12-lead ECG during biventricular pacing with VV interval programmed to 0. Patients with electrocardiographic evidence of ANS underwent detailed echocardiography. We screened 224 patients, 187 patients were excluded due to various causes. Thirty-seven subjects were analysed for this study. Anodal stimulation was found in 29 patients (78.4%) by primary screening. Twelve patients (41.4%) showed electrocardiographic evidence of ANS by 12-lead ECG. The ANS threshold was significantly higher than true bipolar LV threshold (4.5±1.7 vs. 1.1±0.3 V, respectively, P=<0.0001). Ten patients, with ECG evidence of ANS, underwent detailed echocardiography during biventricular pacing with and without ANS. Overall, there were no significant differences in the haemodynamic, echocardiographic, or resynchronization effects with and without ANS, two patients showed significant reduction in LV function with ANS.
  
  
  CONCLUSIONS
  Anodal stimulation is a common phenomenon among CRT patients. In many cases ANS is seen with LV pacing only, while these changes may not be seen by ECG during biventricular pacing. Echocardiography did not show any significant acute haemodynamic benefit during ANS, and some patients may even deteriorate.
authors.affiliation: Davidai Arrhythmia Center, Tel-Aviv University, Tel Hashomer, Israel.
authors.forename: Raed
authors.initials: R
authors.lastname: Abu Sham'a
authors.forename: Rafael
authors.initials: R
authors.lastname: Kuperstein
authors.forename: Alon
authors.initials: A
authors.lastname: Barsheshet
authors.forename: David
authors.initials: D
authors.lastname: Bar-Lev
authors.forename: David
authors.initials: D
authors.lastname: Luria
authors.forename: Osnat
authors.initials: O
authors.lastname: Gurevitz
authors.forename: Sharona
authors.initials: S
authors.lastname: Bachar
authors.forename: Michael
authors.initials: M
authors.lastname: Eldar
authors.forename: Micha
authors.initials: M
authors.lastname: Feinberg
authors.forename: Michael
authors.initials: M
authors.lastname: Glikson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000503:physiopathology* / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy / Q000379:methods; D058409:Cardiac Resynchronization Therapy Devices; D004562:Electrocardiography; D004566:Electrodes; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*