Comparison of cathodal, anodal, and bipolar strength-interval curves with temporary and permanent pacing electrodes.
TLDR
Under appropriate physiological conditions and competitive pacing, patients would be more vulnerable to arrhythmias with bipolar stimulation than with unipolar cathodal, so the anodal surface area should be 5 to 7 times the cathode, or the anode should be removed from the ventricle, to decrease that risk.Abstract:
premature contractions is greater during bipolar or anodal stimulation than with unipolar cathodal (with electrodes of equal cathodal and anodal surface area) because the anodal and bipolar absolute refractory periods are shorter, enabling easier excitation in the vulnerable period. To compare the relative safety of stimulation with various commercial electrodes, strength-interval curves were determined in patients during the initial period after electrode implantation (acute studies) and after a few years of pacing (chronic studies). In 9 of 10 acute studies in patients with permanent bipolar electrodes (anode surface area 4-4 times cathode) and in 9 of 10 chronic studies in patients with bipolar electrodes, the unipolar cathodal and bipolar refractory periods were equal. However, in 7 of 12 patients with temporary bipolar electrodes (equal anodal and cathodal surface areas) and in 2 out of 20 acute and chronic studies in patients with permanent bipolar electrodes, the bipolar refractory periods were significantly shorter than cathodal because of anodal stimulation at the proximal electrode. Under appropriate physiological conditions and competitive pacing, these patients would be more vulnerable to arrhythmias with bipolar stimulation than with unipolar cathodal. To decrease that risk, the anodal surface area should be 5 to 7 times the cathodal, or the anode should be removed from the ventricle, especially for temporary pacing in circumstances of high vulnerability to arrhythmias.read more
Citations
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A mathematical model of make and break electrical stimulation of cardiac tissue by a unipolar anode or cathode
TL;DR: Numerical simulations of electrical stimulation of cardiac tissue using a unipolar extracellular electrode using the bidomain model with unequal anisotropy ratios represented the tissue and the Beeler-Reuter model represented the active membrane properties resulted in similar strength-frequency curves.
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Strength-interval curves for cardiac tissue predicted using the bidomain model.
TL;DR: Cardiac Strength‐Interval Curves are predicted for unipolar anodal and cathodal stimulation of cardiac muscle.
Journal ArticleDOI
Evaluation of electrode polarity on defibrillation efficacy
TL;DR: This prospective, randomized evaluation of electrode polarity on defibrillation thresholds was performed in 21 survivors of ventricular fibrillation (VF) undergoing cardiac surgery, finding no differences in resistance with the 2 configurations.
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Virtual electrode theory explains pacing threshold increase caused by cardiac tissue damage
TL;DR: The study explains failure to stimulate damaged tissue within the concepts of the VEP theory by investigating the influence of acute tissue damage produced by continuous pacing with strong current on stimulus-generated VEPs and pacing thresholds.
References
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Ventricular fibrillation due to single, localized induction and condenser shocks applied during the vulnerable phase of ventricular systole
Carl J. Wiggers,René Wégria +1 more
TL;DR: It is shown that in order to produce premature contractions by shocks applied during systole it was necessary to utilize very strong break shocks, and in the zeal to elicit such contractions ventricular fibrillation all too often terminated the experiment.
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Excitability of the heart
Journal ArticleDOI
Ventricular fibrillation and competitive pacing.
TL;DR: The cause of death in persons with artificial pacemakers is a continuing and disturbing problem and causes include pacemaker-catheter displacement, electric-component failure, broken wires and rising pacing.
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Repetitive ventricular arrhythmia resulting from artificial internal pacemaker.
Morton E. Tavel,Charles Fisch +1 more
TL;DR: A patient is presented in whom several periods of repetitive ventricular arrhythmia—at times indistinguishable from fibrillation—were induced by artificial internal pacemaker stimuli falling in the T wave of a preceding cycle (the vulnerable period).
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Anodal excitation of cardiac muscle.
TL;DR: The strength-interval curve of dog ventricular myocardium has been measured with anodal and cathodal stimulation and it is shown that during diastole the anodals threshold is higher than the cathodals.