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Pulse Width Dependent Increase in the Pacemaker Automatic Interval
Author(s) -
OHM OLEJÖRGEN,
BREIVIK KJELL,
HAMMER ERLING
Publication year - 1982
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1982.tb02239.x
Subject(s) - medicine , interval (graph theory) , cardiology , artificial cardiac pacemaker , pulse (music) , combinatorics , electrical engineering , voltage , engineering , mathematics
From a total of 51 patients equipped with rate and pulse width adjustable pulse gen erators (Microlith‐P 0505, Microthin‐PI 0522) implanted over the last 3 years, 10 (19.6%) showed an un expected drop in pacemaker pulse rate during pulse width programming. For one of the pulse gen erators used (Microthin‐PI 0522), unexpected rate decrease occurred in 7/13 cases (53.8%). For all ex cept one patient, decrease in pacemaker pulse rate corresponded with the total refractory period of the pulse generator (320 ms), at a certain pulse width when rate drop first occurred. In seven of the patients the pulse generator automatic interval was extended from 13 ms to 171 ms beyond the re fractory period. In two patients it was necessary to replace the pulse generators. Our study strongly proves that this abnormal pacemaker functioning is a result of sensing of the polarization voltage at the pacemaker electrode/tissue interface and/or the T‐wave. The polarization voltage is highly dependent on the total pacemaker electrode/tissue interface impedance. Using typical values for pulse genera tor output and input resistance and output capacitance, Faraday resistance, Helmholtz capacitance and tissue resistance at the electrode/tissue interface it was shown mathematically that in some cases the polarization voltage alone would be of sufficient amplitude and slew rate for pacemaker inhibi tion. The study demonstrates an urgent need for change in the filter characteristics by making the pulse generators less sensitive in the low frequency region and reducing the polarization voltage by reducing the output circuit capacitance. (PACE, Vol. 5, May‐June, 1982)