MECHANISMS OF ATRIAL-FIBRILLATION - RECEN T PROGRESS AND THERAPEUTIC INDICATIONS

Atrial fibrillation is usually due to multiple microreentry circuits, However, in some cases, the initial arrhythmia inducing the atrial fib rillation may be an abnormal automatism, or a macroreentry, The initia l abnormalities may induce a desynchronization due to multiple macrore entry circuits, The main factors of atrial vulnerability are intra-atr ial conduction disturbances and changes in refractory periods, Critica l mass and effects of autonomic nervous system may also play a role, S hortened refractory periods and decreased conduction velocity imply a short wavelength and an important arrhythmogenic risk. On the other ha nd, the longer the duration of atrial fibrillation, the more refractor y periods will shorten and the more atrium will become vulnerable: atr ial fibrillation tends to beget atrial fibrillation because of an elec trophysiologic remodelage, In some cases atrial fibrillation, if its d uration is long and if its rate is high, may be responsible for the de velopment of a tachycardiomyopathy, The knowledge of atrial fibrillati on mechanism may have interesting therapeutic implications such as res ynchronization of the atria by stimulation or ablation, for example in the approaches comparable to the maze operation.