title: Optimal side of implant for single-lead VDD pacing: right-sided versus left-sided implantation.
abstract: BACKGROUND
  Atrial undersensing occurs in a considerable number of patients with single-lead VDD pacing. This study tried to determine the role of implant side in maintenance of the VDD mode in patients with isolated atrioventricular (AV) block.
  
  
  METHODS
  Eighty-two patients with isolated AV block (46 females; mean age, 58 +/- 17 years) received a single-lead VDD pacemaker (Medtronic Kappa, n = 70 and St. Jude Medical Affinity, n = 12). The patients were randomly assigned to one of two implantation groups (group I: right-sided VDD and group II: left-sided VDD). In each group, the P-wave amplitudes were determined at implantation, predischarge, 2-month, and 6-month follow-up. At each follow-up visit, stored event histograms of pacemaker were also retrieved. The atrial sensing measurements were compared between two groups.
  
  
  RESULTS
  Implantation was easier from right side (1.7 +/- 1.0 vs 2.8 +/- 1.7 attempts, P = 0.001). Implant P-wave was higher in group I compared to group II (4.2 +/- 1.7 vs 2.7 +/- 1.0 mV, P < 0.0001). During follow-up, higher P-wave amplitudes were obtained in group I both at predischarge (2.6 +/- 1.3 vs 1.4 +/- 1.1 mV, P < 0.0001), 2-month (2.8 +/- 1.8 vs 1.3 +/- 1.0 mV, P < 0.0001), and 6-month (2.9 +/- 1.7 vs 1.3 +/- 0.9 mV, P < 0.0001) evaluations but remained stable throughout the 6 months in both groups. After implantation, VDD function was better maintained in group I than group II (100% vs 90%, P = 0.026). Incidence of atrial undersensing was lower in group I than group II (P = 0.026) in last follow-up visit.
  
  
  CONCLUSIONS
  Implant side has a significant influence on atrial sensing performance in single-lead VDD pacing. Thus, right-side implantation should be the preferred approach for the implantation of VDD single-lead systems.
authors.affiliation: Department of Pacemaker and Electrophysiology, Shahid Rajaie Cardiovascular Center, School of Medicine, Iran University of Medical Sciences, Tehran, Iran. haghjoo@rhc.ac.ir
authors.forename: Majid
authors.initials: M
authors.lastname: Haghjoo
authors.forename: Arash
authors.initials: A
authors.lastname: Arya
authors.forename: Zahra
authors.initials: Z
authors.lastname: Emkanjoo
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Sadr-Ameli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006327:Heart Block / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome