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Electrophysiological studies on atrial fibrillation
1School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.
Heart and Vessels. Supplement
|January 1, 1987
Summary
The multiple-wavelet hypothesis for atrial fibrillation is supported by animal studies. Larger atria in cows and mules sustain atrial fibrillation longer than smaller atria in calves and goats.
Area of Science:
- Cardiology
- Veterinary Medicine
- Electrophysiology
Background:
- Atrial fibrillation (AF) is a common arrhythmia.
- The multiple-wavelet hypothesis proposes that AF is maintained by multiple reentrant wavelets.
- Understanding AF initiation and maintenance is crucial for developing effective treatments.
Purpose of the Study:
- To test the multiple-wavelet hypothesis for AF initiation and maintenance.
- To investigate the role of atrial size and maturity in AF persistence.
- To analyze the ventricular response during AF.
Main Methods:
- Atrial fibrillation was induced and studied in various animal models including mules, horses, cows, calves, and goats.
- Rapid atrial pacing was used to initiate AF.
- Atrial size and myocardial maturity were assessed.
- Ventricular response and atrioventricular nodal conduction were analyzed using microelectrodes and His bundle recordings.
Main Results:
- AF persisted significantly longer in animals with larger atria (cows, mules) compared to those with smaller atria (calves, goats).
- AF duration was related to atrial size, not atrial myocardial maturity.
- In some cases, rapid atrial responses were concealed within the atrioventricular node, and one instance of infranodal block was observed.
- Subsidiary pacemakers did not appear to cause ventricular irregularity during AF.
Conclusions:
- The findings support the multiple-wavelet hypothesis for AF initiation and maintenance.
- Atrial size is a critical determinant of AF persistence.
- The atrioventricular node plays a significant role in modulating the ventricular response during AF.