Key result
Failure of ventricular stimulation in dogs with induced heart block was due to wire breakage or loss of contact, not excessive scarring, despite scar tissue requiring more power.
Why the study?
What is the cause of pacemaker failure in dogs with induced AV block and electrodes implanted in normal vs scar tissue?
What is the cause of pacemaker failure in dogs with induced AV block and electrodes implanted in normal vs scar tissue?
In a canine model of AV block, pacemaker failure was caused by mechanical issues (wire breakage or loss of contact) rather than excessive scarring.
Answers are grounded in this paper and cite their sources.
Mechanical lead failure predominates over scarring in this canine model; leaves open relevance to human pacemaker implantation.
Atrioventricular conduction blocks were produced in dogs, and ventricular stimulation was accomplished by the use of electrodes implanted either into normal myocardium or scar tissue on the myocardium. Stimulation through scar tissue requires several times the power necessary for stimulation through normal myocardium, but both are well within the limit of standard, commercially available, transistorized pacemakers. Failure of stimulation of the ventricle was not due to excessive scarring. Failure of stimulation was in every instance due to wire breakage or actual loss of contact between the wire and the myocardium.
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Albert et al. (1962) studied Atrioventricular conduction blocks. Ventricular stimulation via electrodes implanted into scar tissue vs. Electrodes implanted into normal myocardium was evaluated on Failure of stimulation. Failure of ventricular stimulation in dogs with induced heart block was due to wire breakage or loss of contact, not excessive scarring, despite scar tissue requiring more power.
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