ATRIOVENTRICULAR NODAL TACHYCARDIAS

The atrioventricular junction consists of the atrioventricular node an d the bundle of His up to its division. All tachycardias arising in th ese structures or which; depend on these structures for their sustenan ce are called ''junctional''. There are four main types. The first thr ee correspond to reciprocating rhythms, nodal tachycardia, tachycardia s using an accessory pathway with unidirectional retrograde conduction , and chronic reciprocating atrioventricular nodal tachycardia. The fo urth, a focal tachycardia, is without doubt due to increased automatic ity: ectopic atrioventricular nodal tachycardia. All varieties of reci procating atrioventricular nodal tachycardia have been well studied an d their diagnosis is possible from the standard surface electrocardiog ram from the position and morphology of the P' wave. They are accessib le to radical treatment by radiofrequency ablation of the slow pathway or accessory pathway, when present. The definitive treatment of ectop ic atrioventricular nodal tachycardia is not yet established and has t o be considered case by case, this form of arrhythmia being rare.