title: Maintaining physiological pacing in AV block using a new generation single lead VDD pacemaker.
abstract: OBJECTIVE
  A prospective evaluation of patients with AV block using a single pass lead, VDD pacing system.
  
  
  METHODS
  Fifteen patients with AV block, eight males, seven females, average age 68.1 years (range 22.3 to 86.5) were implanted with the THERA VDD 8948 pacemaker and 5032 single pass steroid eluting lead (Medtronic, Inc). P wave sensing and ventricular thresholds were done predischarge and at one, three, and six months and subsequent six-month periods postimplant. P wave sensing was evaluated with exercise testing and other provocative tests. Twenty-four hour Holter monitoring was done before discharge. Patients were given a quality of life questionnaire pre- and postimplant.
  
  
  METHODS
  Tertiary care hospital.
  
  
  RESULTS
  Average follow-up was 6.4 months (1.5 to 18). Ventricular thresholds remained stable. P wave amplitude at implant (average 2.2 mV; 1.6 to 3.6) showed a significant decrease at the initial visit (average 1.1 mV, 0.5 to 2.4), however, it remained stable at subsequent visits. This initial decrease had no clinical significance as the maximum atrial sensitivity of the device is 0.18 mV. The 24 hr Holter monitoring confirmed reliable AV synchronous pacing in 14 of 15 patient pacemakers programmed in the VDD mode. The sleep function maintained AV synchrony during nocturnal bradycardia; atrial rate histograms available at follow-up imply appropriate intrinsic rate variation and provocative sensing tests and exercise protocol demonstrated reliable atrial sensing. There was a significant improvement in overall patient well-being score using a quality of life questionnaire.
  
  
  CONCLUSIONS
  During the follow-up period, this new generation VDD pacemaker, using a single pass lead, provided reliable AV synchronous pacing for patients diagnosed with AV block and normal sinus node function, as well as improved patient well-being.
authors.affiliation: Division of Cardiology, Sunnybrook Health Science Centre, University of Toronto, Ontario.
authors.forename: C
authors.initials: C
authors.lastname: Lau
authors.forename: S C
authors.initials: SC
authors.lastname: Nishimura
authors.forename: A W
authors.initials: AW
authors.lastname: Harrison
authors.forename: B S
authors.initials: BS
authors.lastname: Goldman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015716:Electrocardiography, Ambulatory; D004867:Equipment Design; D005080:Exercise Test; D005260:Female; D006327:Heart Block / Q000175:diagnosis / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000523:psychology / Q000592:standards*; D011446:Prospective Studies; D011788:Quality of Life; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D016896:Treatment Outcome