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Atrial fibrillation in most patients initiates as a
primary arrhythmia or follows an atrial premature beat occurring during atrial vulnerable
period. In other patients atrial fibrillation results from the degeneration of another
supraventricular tachycardia, a phenomenon E.N. Pristowsky1
referred to as tachycardia-induced tachycardia.
A number of supraventricular tachycardias can trigger atrial fibrillation: focal
atrial tachycardia, common and uncommon atrial flutter, atrioventricular reentrant
tachycardia (related to an overt or a concealed Kent bundle) and atrio-ventricular nodal
reentrant tachycardia. Potential factors affecting conversion of sustained atrial and
nonatrial tachycardias to atrial fibrillation include tachycardia cycle length2-4, electrophysiological characteristics of the
triggering arrhythmia1 and contraction-excitation
feed-back5. As to the latter phenomenon, it has been
demonstrated that some paroxysmal supraventricular tachycardias give rise to a sudden
dilatation of the atria1. Consequently, as changes in
mechanical stress can alter cardiac membrane potential (contraction-excitation feedback)5, it is possible that sudden dilatation of the atria
affects cardiac membrane potential and leads to atrial fibrillation.
Recently it has been suggested that in patients with tachycardia-induced tachycardia
radiofrequency ablation of the triggering arrhythmia is able to prevent also atrial
fibrillation2-3, 6-9. Unfortunatly the diagnosis of
tachycardia-induced atrial fibrillation is not always easy and the existence of a second
supraventricular arrhythmia in addition to atrial fibrillation is frequently ignored.
Finally the association of a supraventricular tachycardia and atrial fibrillation not
always means that the former is the trigger of the latter. Therefore not always the
ablation of the former arrhythmia is able to eliminate also atrial fibrillation.
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