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Triggered activity as a cause of bigeminy
Journal of the American College of Cardiology
|September 1, 1986
Summary
Bigeminal rhythms in ouabain-toxic canine Purkinje fibers stem from alternans in afterdepolarizations and diastolic potentials. This finding suggests bigeminy can be a form of sustained triggered activity, not just reentry.
Area of Science:
- Cardiology
- Electrophysiology
- Pharmacology
Background:
- Ouabain toxicity can induce cardiac arrhythmias.
- Triggered activity is a known mechanism for arrhythmias.
- Bigeminal rhythms have complex underlying causes.
Purpose of the Study:
- To investigate the mechanism of bigeminal rhythms during triggered activity in ouabain-toxic canine Purkinje fibers.
- To determine if alternans in afterdepolarizations contribute to bigeminy.
- To re-evaluate the origins of bigeminal rhythms in this context.
Main Methods:
- Standard microelectrode techniques were employed.
- Experiments were conducted on ouabain-toxic canine Purkinje fibers.
- Analysis focused on triggered activity and associated afterdepolarizations.
Main Results:
- Bigeminal rhythms were observed during stable triggered activity.
- An alternans phenomenon in delayed afterdepolarizations was identified as the basis for bigeminy.
- Alternans were also noted in the maximal diastolic potential.
Conclusions:
- Bigeminy in this model is linked to alternans in delayed afterdepolarizations and maximal diastolic potential.
- The findings support the view that bigeminy can be a manifestation of sustained triggered activity.
- This challenges previous assumptions about bigeminy arising solely from reentry or parasystole.