Non-Flutter Atrial Tachycardia

"Non-flutter" atrial tachycardias are uncommon tachycardia defined as supraventricular arrhythmias that do not require the AV node or accessory pathway or macroreentrant circuit for perpetuation.They include mainly focal atrial tachycardias. The three possible mechanisms are automaticity, triggered activity and microreentry. Generally focal atrial tachycardia is characterized by P wave separated by an isoelectric interval in all electrocardiographic leads but when atrial rate is very rapid (more than 250 beats/mn), they mimic macroreentrant atrial tachycardia or others forms of supraventricular tachycardias. Sometimes an electrophysiological study is required for a definitive diagnosis of focal atrial tachycardia.The tachycardia could be paroxysmal or incessant. The re-entry or triggered activity is the basic mechanism of paroxysmal form and the incessant form of atrial tachycardia has abnormal automaticity as the main mechanism of the arrhythmia. The sites of tachycardia origin are distributed over preferential anatomic localisations : crita terminalis, pulmonary veins ostium, coronary sinus os musculature, atrioventricular annulus and atrial septum. Analyse of P wave morphology could predict the site of origin of tachycardia. These tachycardias may be cured with focally directed radiofrequency application.The success rate is high and is independent of the putative mechanism. The development of 3D mapping systems has simplified the mapping and the ablation of focal tachycardia.