Mechanisms of atrial fibrillation

The electrophysiologic mechanisms basis of atrial fibrillation have been extensively investigated in animal models and clinical electrophysiology. Short atrial refractoriness and slow conduction are constant findings in AF patients. Less information is available about human atrial fibrillation behaviour, expecially regarding its self termination and persistence. Fourteen patients with lone paroxysmal atrial fibrillation underwent an electrophysiologic study. Mean and P5 of 100 consecutive FF intervals were evaluated at 3 atrial sites either at arrhythmia onset or at self termination (or at the 5th minute). Twenty-eight atrial fibrillation episodes were induced: 21 self terminating within 5 minutes, and 7 long lasting. A significant correlation was found between mean FF interval and atrial functional refractory period (r = 0.79, p < 0.001), and between P5 FF interval and atrial effective refractory period (r = 0.6, p < 0.005). Atrial fibrillation self termination was associated with significant mean FF prolongation, while long lasting fibrillation behaved the opposite. The FF intervals analysis during fibrillation showed a significant relation to atrial electrophysiologic properties and offer a useful parameter for the comprehension of AF spontaneous behaviour and for the evaluation of therapeutic interventions.