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Intrathoracic Impedance Preceding Ventricular Tachyarrhythmia Episodes
Author(s) -
MOORE HANS J.,
PETERS MATTHEW N.,
FRANZ MICHAEL R.,
KARASIK PAMELA E.,
SINGH STEVEN N.,
FLETCHER ROSS D.
Publication year - 2010
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.1540-8159.2010.02746.x
Subject(s) - medicine , cardiology , ohm , heart failure , quantum mechanics , physics
Background: Heart failure is associated with ventricular tachyarrhythmias (VT/VF). Fluid accumulation during worsened heart failure may trigger VT/VF. Increased intrathoracic impedance has been correlated with fluid accumulation during heart failure. Implanted defibrillators capable of daily measures of intrathoracic impedance allow correlation of impedance with occurrence of VT/VF. We hypothesized that VT/VF episodes are preceded by decreases in intrathoracic impedance. The goal was to identify the relationship of intrathoracic impedance measured by implanted cardioverter defibrillators to the occurrence of VT/VF.Method: Implanted defibrillator follow‐up data were obtained retrospectively. Those with Medtronic OptiVol (Medtronic Inc., Minneapolis, MN, USA), storing averaged daily and reference impedance values, were reviewed for VT/VF episodes. Impedance changes in the week leading up to VT/VF were analyzed.Results: A total of 317 VT/VF episodes in a cohort of 121 patients’ follow‐up data were evaluated. Averaged daily intrathoracic impedance declined preceding 64% of VT/VF episodes, with an average decline of 0.46 ± 0.35 Ohms from the day before the VT/VF episodes. However, the mean values of the averaged daily and reference impedance did not change significantly. A novel measure, ΔTI, the sum of the daily differences between the averaged daily and reference impedance, was negative preceding 66% of VT/VF episodes (P < 0.001). The mean ΔTI was −4.0 ± 1.3 Ohms, which was significantly lower than the theoretically expected value of zero Ohms (P < 0.01).Conclusion: (1) Averaged daily impedance declined preceding 64% of VT/VF episodes, but the overall decline was of small magnitude; (2) a novel measure, ΔTI, was negative preceding 66% of VT/VF episodes, and significantly below zero. (PACE 2010; 33:960–966)