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Intracardiac QRS Electrogram Width—An Arrhythmia Detection Feature for Implantable Cardioverter Defibrillators: Exercise Induced Variation as a Base for Device Programming
Author(s) -
KLINGENHEBEN THOMAS,
STICHERLING CHRISTIAN,
SKUPIN MANFRED,
HOHNLOSER STEFAN H.
Publication year - 1998
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.1540-8159.1998.tb00250.x
Subject(s) - medicine , qrs complex , cardiology , ventricular tachycardia , electrocardiography , supraventricular tachycardia , intracardiac injection , tachycardia , anesthesia
Delivery of inappropriate therapy of implantahle cardioverter defibrillators (ICD) due to inaccurate arrhythmia detection represents a major clinical problem. Different arrhythmia detection criteria such as the “stability” of the cycle length or the suddenness of “onset” of tachycardia have been implemented in ICD software to prevent inappropriate therapy. The new Medtronic model 7223Cx ICD offers an additional detection parameter (QHS width), which reflects changes in the duration of ventricular depolarization as a tool to distinguish supraventricular from ventricular tachycardias. Although this criterion can be programmed based on ECG parameters derived from resting ECGs, this may not be sufficient since QRS width is subject to considerable changes due to transient myocardial ischemia, changes in autonomic tone, or frequency dependent effects of antiarrhythmic drugs. The present study aimed to determine frequency dependent changes in QRS width in individual patients at rest and during symptom‐limited exercise testing in 16 patients with documented ventricular tachycardia (N = 13) or ventricular fibrillation (N = 3). The optimal EGM slew threshold and the individual variation of QRS width were determined. Measurements obtained at the end of the implantation procedure were compared to those performed at hospital discharge. The majority of patients showed a wider variation in QRS duration as measured from 30 consecutive cycles during exercise as compared to rest. For example, the QRS range (i.e., the difference between the maximal and the minimal QRS width measured) averaged 7 ± 3 ms at rest and increased to 11 ±3 ms during exercise (P = 0.004) with an increase of ≥ 4 ms observed in 11 (69%) of 16 patients. In 13 (81%) of 16 patients a reprogramming of at least one QRS width parameter from its value at the time of implantation was necessary. Thus, the QRS width measured from the intracardiac EGM shows significant intra‐individual variations in different physiological conditions. Eor optimal programming of the QRS width parameter, measurements obtained during exercise are important.