During typical<unk> , electrical impulses travel down the slow pathway of the<unk>  node and back up the fast pathway. The fundamental mechanism of<unk>  is a re-entrant circuit within the atrioventricular node. This can take several forms. "Typical", "common", or "slow-fast"<unk>  uses the slow<unk><unk>  pathway to conduct towards the ventricle (the anterograde limb of the circuit) and the fast<unk><unk>  pathway to conduct to the atria (the retrograde limb). The re-entrant circuit can be reversed such that the fast<unk><unk>  pathway is the anterograde limb and the slow<unk><unk>  pathway is the retrograde limb, referred to as "atypical", "uncommon", or "fast-slow"<unk> . Atypical<unk>  may also use the slow<unk><unk>  pathway as the anterograde limb and left atrial fibres that approach the<unk>  node from the left side of the inter-atrial septum as the retrograde limb, and is sometimes referred to as "slow-slow"<unk> . Typical<unk>  In typical<unk> , the anterograde conduction is via the slow pathway and the retrograde conduction is via the fast pathway ("slow-fast"<unk> . Because the retrograde conduction is via the fast pathway, stimulation of the atria (which produces the inverted P wave) occurs very soon after stimulation of the ventricles (which causes the QRS complex). As a result, the time from the QRS complex to the P wave (the RP interval) is short, less than 50% of the time between consecutive QRS complexes. The RP interval is often so short that the inverted P waves may not be seen on the surface electrocardiogram (ECG) as they are buried within or immediately after the QRS complexes, appearing as a "pseudo R prime" wave in lead V1 or a "pseudo S" wave in the inferior leads. Atypical<unk>  In atypical<unk> , the anterograde conduction is via the fast pathway and the retrograde conduction is via the slow pathway ("fast-slow"<unk> . Multiple slow pathways can exist so that both anterograde and retrograde conduction are over slow pathways. ("slow-slow"<unk> .Because the retrograde conduction is via the slow pathway, stimulation of the atria will be delayed by the slow conduction tissue and will typically produce an inverted P wave that falls after the QRS complex on the surface ECG.
AV nodal reentrant tachycardia
Tachycardia
Re-entry ventricular arrhythmia
Junctional ectopic tachycardia
Atrioventricular reentrant tachycardia
Wandering atrial pacemaker
Pre-excitation syndrome
Ventricular escape beat