Increasing tissue area, width, and weight, and decreasing effective refractory periods and wavelengths were significantly associated with an increased probability of sustained AF (P<0.001).
Does tissue geometry and refractory period affect the probability of sustaining atrial fibrillation in isolated canine atria?
Sustained atrial fibrillation probability is significantly associated with larger tissue dimensions and shorter effective refractory periods and wavelengths, supporting the critical mass hypothesis.
p-value: p=<0.001
BACKGROUND: The critical mass hypothesis for atrial fibrillation (AF) was proposed in 1914. There has never been a systematic investigation defining the relationship between tissue geometry and AF. The purpose of this study was to determine the association among the probability of maintaining AF and the width, area, weight, effective refractory period (ERP), and wavelength in atrial tissue. METHODS AND RESULTS: Isolated canine atria (n=20) were perfused with Krebs-Henseleit solution. Baseline ERPs were obtained with and without acetylcholine (10E-3.5 mol/L) using single extra-stimulus pacing while unipolar electrograms were recorded from 250 sites. The tissue was then partitioned using bipolar radiofrequency ablation, and the ERPs were measured again with and without acetylcholine. Any section of tissue that maintained AF was divided until the arrhythmia was no longer inducible. ERPs and conduction velocities were measured in all of the sections after each ablation, and the wavelengths were calculated. The probability of AF was found to be correlated with increasing tissue areas, widths, and weights (P<0.001). The probability of AF was significantly associated with the length of the ERP and the wavelength (P<0.001). With shorter ERPs and shorter wavelengths, there was an increased probability of sustained AF. CONCLUSIONS: The probability of sustained AF was significantly associated with increasing tissue area, width, and weight and decreasing ERPs and wavelengths. These data may lead to a better understanding of the mechanism of AF and, thus, help to design more-effective interventional procedures in the future.
Byrd et al. (Tue,) conducted a other in Atrial fibrillation (n=20). Tissue partitioning via bipolar radiofrequency ablation was evaluated on Probability of maintaining AF (p=<0.001). Increasing tissue area, width, and weight, and decreasing effective refractory periods and wavelengths were significantly associated with an increased probability of sustained AF (P<0.001).
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