title: Activity-based rate-adaptive pacemakers under hyperbaric conditions.
abstract: OBJECTIVE
  The aim of this study was to test a variety of currently available activity-based rate-adaptive pacemakers under hyperbaric conditions.
  
  
  BACKGROUND
  Sports divers with pacemakers can dive under certain circumstances. The rate response of activity-sensing pacing under hyperbaric conditions has rarely been evaluated.
  
  
  METHODS
  We manufactured a miniaturized hyperbaric chamber. A pacemaker inside was kept close to the corresponding telemetry wand placed on top of the chamber. An inflation device for coronary balloon angioplasty was used to create hydraulic pressure. Group I pacemakers were exposed to a 30 msw/98 fsw/4 ATA and after a 1-month waiting period to 60 msw/197 fsw-depth/7 ATA. Group II was exposed to only one dive to 60 msw. The electrogram and event marker telemetry were used to monitor the pacing stimuli and measurements were made for case distortion.
  
  
  RESULTS
  The baseline pacing rate did not change in 27 tests. Return to baseline was shown during 18 tests after transient sensor-driven rate. There was a sensor rate response to manual brief shaking during and following testing. A case distortion was shown in 15 of 29 tests at 60 m.
  
  
  CONCLUSIONS
  Modern accelerometers showed no sensitivity to pressure on the pacemaker can at 30 msw/98 fsw and 60 msw/197 fsw but in some devices responded to pressure changes. There was no pacing dysfunction or suppression of the sensor response despite the high incidence of case distortion at 60 msw/197 fsw. As a general rule, diving should not be allowed at depths greater than 20 msw/65 fsw.
authors.affiliation: Department of Cardiology, Centre Hospitalier Universitaire Nord, 13915 cedex 20, Marseille, France. alexandre.trigano@mail.ap-hm.fr
authors.forename: Alexandre
authors.initials: A
authors.lastname: Trigano
authors.forename: Vincent
authors.initials: V
authors.lastname: Lafay
authors.forename: Olivier
authors.initials: O
authors.lastname: Blandeau
authors.forename: Samuel
authors.initials: S
authors.lastname: Levy
authors.forename: Bernard
authors.initials: B
authors.lastname: Gardette
authors.forename: Christophe
authors.initials: C
authors.lastname: Micoli
mesh_terms: D004242:Diving; D004867:Equipment Design; D019544:Equipment Failure Analysis; D010138:Pacemaker, Artificial; D011312:Pressure