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Threshold, enzymatic, and pathologic changes associated with prolonged transcutaneous pacing in a chronic heart block
J R Hedges1, S A Syverud, W C Dalsey
1Department of Emergency Medicine, University of Cincinnati College of Medicine, Ohio.
The Journal of Emergency Medicine
|January 1, 1989
Summary
Sixty minutes of transcutaneous cardiac pacing (TCP) in dogs with heart block did not significantly increase cardiac damage or affect pacing thresholds. This suggests TCP is a safe emergency pacing technique before transvenous cardiac pacing (TVP).
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Pacing
Background:
- Transcutaneous cardiac pacing (TCP) for 30 minutes may cause minor myocardial damage.
- Prolonged TCP could potentially increase capture thresholds for transvenous cardiac pacing (TVP).
Purpose of the Study:
- To evaluate the safety and effects of 60-minute TCP on myocardial damage and pacing thresholds in a canine heart block model.
Main Methods:
- Chronic heart block was induced in dogs via His bundle ablation.
- Six dogs underwent 60 minutes of TCP; cardiac enzymes and pacing thresholds were monitored.
- Histopathological examination of cardiac tissue was performed post-pacing.
Main Results:
- A significant rise in creatine kinase (CK) was observed, but the MB fraction remained undetectable.
- No significant elevation in lactate dehydrogenase (LDH) occurred, though some isoenzyme shifts indicated minor damage.
- Histology showed minimal myocardial degeneration (<1%) in some paced animals.
- No significant changes in TCP or TVP capture thresholds were detected after 60 minutes of TCP.
Conclusions:
- Sixty minutes of TCP in this model did not cause significant myocardial damage or alter pacing thresholds.
- TCP appears to be a safe emergency pacing method prior to TVP, even for extended durations.