Electrophysiological properties of the human atrium in atrial fibrillation.

It has been reported that ectopic foci from the pulmonary veins can initiate atrial fibrillation (AF) and can also act as drivers for maintaining AF. However, not all patients with atrial arrhythmias initiate AF. A substrate for atrial propensity to AF is required for AF initiation and maintenance. Thus, we reviewed and discussed mainly the electrophysiological properties observed in AF. Abnormal atrial electrograms during sinus rhythm and abnormal responses of the atrium elicited by programmed stimulation have been observed more frequently in patients with paroxysmal AF than in those without. A shorter atrial effective refractory period, greater dispersion of the atrial refractoriness and atrial conduction delay are also of electrophysiologic significance in the genesis of AF. Electrical remodeling is likely to be a final common pathway that ultimately supervenes. Even if atrial electrical remodeling facilitates AF initiation and AF perpetuation, the initiation of AF requires a trigger. Further investigation into the electrophysiological properties in AF will be needed in order to contribute to the future development of an appropriate treatment.