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Low Voltage Direct Current Delivered Through Unipolar Transvenous Leads: An Alternate Method for the Induction of Ventricnlar Fibrillation
Author(s) -
EULER DAVID E.,
WHITMAN TERESA A.,
ROBERTS PAUL R.,
KALLOK MICHAEL J.
Publication year - 1999
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.1540-8159.1999.tb06815.x
Subject(s) - medicine , stimulation , stimulus (psychology) , ventricular fibrillation , alternating current , electromagnetic coil , voltage , direct current , resistor , cardiology , biomedical engineering , electrical engineering , psychology , psychotherapist , engineering
The induction of VF during testing of an ICD may not always he possible using either hurst pacing or high energy T wave shocks. The purpose of this study was to evaluate the effectiveness of low energy DC stimulation for inducing VF in a porcine model. The VFT was measured using constant voltage stimuli and a step‐up method in ten anesthetized pigs (25–30 kg). Stimuli of different durations (0.5, 1.0, 2.0 s) were delivered (unsynchronized) between a right ventricular apical coil and a subcutaneous test can. Current was measured from the voltage drop across a series resistor (10 Ω). With anodal stimulation, VF required 6.4 ± 0.2 V compared to 13.8 ± 0.6 V with cathodal stimulation (P < 0.001). The current required to induce VF (measured 10 ms after the stimulus onset) was 58.3 ± 2.2 mA with anodal stimulation and 119.3 ± 4.7 mA with cathodal stimulation (P < 0.001). Stimulus duration did not significantly influence the voltage or current required for VF induction. In 6 of the 10 pigs, synchronizing a 0.5‐second stimulus to the R wave did not significantly alter the VFT compared to same stimulus synchronized to mid‐upslope of the T wave. The results indicate that VF can he consistently induced through transvenous electrodes hy passing unsynchronized DC for 0.5–2 seconds. The induction of VF required about 50% less current and voltage with anodal stimulation. It should be possible to induce VF with the DC voltage available from the internal hattery source of an ICD.