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Dual Level Sensing Significantly Improves Automatic Threshold Control for R Wave Sensing in Implantable Defibrillators
Author(s) -
BREWER JAMES E.,
PERTTU JOSEPH S.,
KROLL MARK W.,
DONOHOO ANN M.
Publication year - 1996
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.1540-8159.1996.tb03278.x
Subject(s) - medicine , sensitivity (control systems) , amplitude , sense (electronics) , electrical engineering , electronic engineering , physics , optics , engineering
ICDs must sense R waves over a range of amplitudes without sensing P or T waves. Automatic threshold control (ATC) is an accepted sensing method for that task. ATC sensing levels are from 25%‐75% of the electrogram (EGM) peak, decreasing with an exponential decay. A high sensing level for a time after peak detection may better allow ATC to pass over a T wave, while a lower sensing level thereafter may better allow ATC to sense the next R wave. An A TC was designed with two sensing levels and time constants (T), using a 58% level (T = 1,75 s) for 325 ms after peak detection switching to 33% (T = 1.1 sj thereafter, and was compared to a single level ATC (sensing level = 50%, T = 1.4 s). The two ATC circuits were tested with 22 arrhythmia EGMs to determine sensitivity and specificity rates at ± 1‐, 2‐, 5‐, 10‐, and 20‐mV amplitudes. It was confirmed that a dual level ATC significantly improves the sensitivity rate without degrading the high specificity rate of a standard sensing circuit.