title: Single lead VDD pacing in children with complete heart block.
abstract: OBJECTIVE
  To evaluate clinically transvenous single lead VDD pacing in children with complete heart block.
  
  
  METHODS
  Case series.
  
  
  METHODS
  Tertiary care unit of a pediatric teaching hospital.
  
  
  METHODS
  Consecutive sample of children with complete heart block requiring pacing and meeting the criteria for VDD pacing.
  
  
  METHODS
  VDD single lead pacing systems (Thera VDD 8948 generator, Capsure VDD 5032 single pass lead) were implanted in nine children (mean age 10.7 years, 95% CI 8.9 to 12.3). All patients were reviewed six weeks and six months post-implantation with clinical review, detailed pacemaker interrogation, optimal device programming, treadmill exercise testing, 24 h Holter monitoring and echocardiography.
  
  
  RESULTS
  Mean procedure time was 62.5 mins (CI 52 to 73), mean fluoroscopy time 3.8 mins (CI 2.4 to 5.1) and mean P wave sensing amplitude 2.75 mV (CI 2.5 to 3), without significant decrease during Valsalva manoeuvre (mean 2.4 mV, CI 2.2 to 2.8). Low pacing thresholds of mean amplitude 0.39 V (CI 0.38 to 0.4) were established at pulse width 0.5 ms. Two patients required early revision--one lead dislodged and one patient had a loose set screw. Follow-up showed satisfactory pacemaker function, and mean percentage atrioventricular (AV) synchronous pacing 96.8% (CI 93 to 99) at six weeks and 97% (CI 95 to 99) at six months. P wave sensing failures were less than 1%. AV synchronous pacing was maintained for more than 99% of the period of treadmill exercise testing. There was a significant mean increase in cardiac output of 24% (CI 8 to 40, P < 0.05) at rest in VDD mode compared with VVIR mode.
  
  
  CONCLUSIONS
  Single lead VDD pacing is an effective and reliable method of 'physiological' rate responsive AV synchronous pacing in children with complete heart block and should be considered a viable alternative to dual lead pacing systems.
authors.affiliation: Department of Cardiology, Izaak Walton Killam Hospital for Children, Halifax, Nova Scotia.
authors.forename: A
authors.initials: A
authors.lastname: Bullock
authors.forename: J
authors.initials: J
authors.lastname: Finley
authors.forename: G
authors.initials: G
authors.lastname: Sharratt
authors.forename: D
authors.initials: D
authors.lastname: Ross
mesh_terms: D000293:Adolescent; D002304:Cardiac Pacing, Artificial; D002648:Child; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D005080:Exercise Test; D005500:Follow-Up Studies; D006327:Heart Block / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D012720:Severity of Illness Index; D016896:Treatment Outcome