title: Time course of current of injury is related to acute stability of active-fixation pacing leads in rabbits.
abstract: BACKGROUND
  Magnitude of current of injury (COI) consequent to pacemaker lead fixation is recognized as a predictor of acute lead stability. It is unclear whether dynamic monitoring of COI after lead fixation provides additional information beyond a single assessment performed at the time of fixation.
  
  
  OBJECTIVE
  This study was aimed to test the hypothesis that the time course of COI is related to acute lead stability.
  
  
  RESULTS
  Active fixation leads with fixed screw were anchored to either Langendorff-perfused rabbit hearts endocardially or in vivo hearts epicardially in manners of contact the helix with no rotation, half rotation and full rotation, respectively. Intracardiac electrogram (EGM) was monitored dynamically from onset to resolution of COI, and magnitudes of intrinsic R wave and COI, including ST-segment elevation, ST/R and intracardiac EGM duration (IED), were measured. A digital force gauge was applied to assess lead stability. In vitro, COI in contacted leads was significantly smaller than those in half rotated (p<0.05) and fully rotated leads (p<0.05), and presented most precipitous recovery to baseline (1.5±1.1 min, p<0.05). Half-rotated and fully rotated leads manifested the same magnitude of COI right after placement. However, the time course of COI was significantly longer in fully rotated leads than that in half rotated leads (26.5±2.8 min vs. 5.6±2.0 min, p<0.05). Similar findings were observed in vivo. The time course of COI was significantly correlated with the force needed to detach the lead from myocardium (r = 0. 72, n = 48, p<0.001).
  
  
  CONCLUSIONS
  Time course of COI is related to acute lead stability in rabbits. One might be misled by a single assessment of COI magnitude right after lead placement, whereas persistence of COI is likely to be a useful indicator of adequate lead stability.
authors.affiliation: Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhong Shan Hospital of Fudan University, Shanghai, China.
authors.forename: Shalaimaiti
authors.initials: S
authors.lastname: Shali
authors.forename: Alimujiang
authors.initials: A
authors.lastname: Wushou
authors.forename: Entao
authors.initials: E
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Jia
authors.forename: Ruiming
authors.initials: R
authors.lastname: Yao
authors.forename: Yangang
authors.initials: Y
authors.lastname: Su
authors.forename: Junbo
authors.initials: J
authors.lastname: Ge
mesh_terms: D000818:Animals; D004567:Electrodes, Implanted; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D004594:Electrophysiology / Q000379:methods; D004867:Equipment Design; D006321:Heart / Q000502:physiology*; D008297:Male; D009206:Myocardium / Q000473:pathology*; D010138:Pacemaker, Artificial; D011817:Rabbits; D013997:Time Factors