title: [Reasons and complications of pacemaker replacement operation: clinical analysis of 69 case-times].
abstract: OBJECTIVE
  To analyze the reasons of cardiac permanent pacemaker replacement and the strategies to prevent relevant complications.
  
  
  METHODS
  The clinical data of 57 patients, 38 males and 19 females, aged 74 +/- 8 (56-94), 31 with sick sinus syndrome, 26 with II or III degree atrioventricular block, who underwent 63 times of cardiac permanent pacemaker replacement, including 13 times of lead replacement, were analyzed.
  
  
  RESULTS
  The reason of replacement included battery normal exhaustion for 57 case-times, battery exhaustion before the defined schedule for 2 case-times, lead electrodes incompletely fractured for 2 case-times, and infection of pacemaker pocket for 2 case-times. There were 9 cases of placement-related complications: pacemaker pocket hematoma (n=4), lead dislocation (n=3), and abandoned leads falling into the right ventricle (n=2). The average lifetime of old pacemakers was 9. 25 years (2 -15 years). The pacing threshold of ventricular leads after pacemaker replacement was (0.77 +/- 0. 40)V, significantly higher than the initial pacing threshold [(0.60 +/- 0.21)V, P < 0.01]. There were no significant differences in the lead impedance and R wave amplitude between the pacemaker replacement and initial implantation [(854 +/- 136)omega vs. (828 +/- 176)omega, and (12 +/- 4)mV vs. (12 +/- 4)mV, both P > 0.05].
  
  
  CONCLUSIONS
  The main reason of pacemaker replacement is battery exhaustion. Most implanted ventricular leads still can be used. A rare serious complication of cardiac pacemaker replacement operation is abandoned lead falling into the right ventricle, and correct disposing of initial leads help avoid this complication .
authors.affiliation: Department of Cardiology, Shijitan Hospital, Beijing 100038, China.
authors.forename: Xue-ling
authors.initials: XL
authors.lastname: Liu
authors.forename: Li-hui
authors.initials: LH
authors.lastname: Ren
authors.forename: Hui-ming
authors.initials: HM
authors.lastname: Ye
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial; D020878:Device Removal / Q000592:standards / Q000706:statistics & numerical data; D011211:Electric Power Supplies; D019544:Equipment Failure Analysis / Q000592:standards / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial