5 Quick Clues to <br />
AV Nodal Reentry Tachycardia <br />

1. Sudden onset/sudden termination: Often a patient will describe tachycardia as starting and stopping abruptly. This suggests a reentrant tachycardia. 2. Retrograde P waves in inferior leads during tachycardia: A 12-lead electrocardiogram (ECG) of the tachycardia (Figure 1) may have shallow S waves in the inferior leads (II, III, aVF) that are not present in a baseline ECG (Figure 2). One may also see an RR pattern in Lead V1. These 12-lead ECG features are generated by the retrograde P-wave during tachycardia. 3. AH jump: An AH interval jump of greater than 50 ms during atrial single extrastimulus programmed stimulation indicates dual AV node physiology (there are two pathways in the AV node fast and slow). (Figure 3) 4. Midline, decremental VA conduction: This type of VA conduction strongly suggests AV node involvement. It is quite rare to have AVNRT without VA conduction. 5. All internal electrograms line up during tachycardia: The appearance of all internal electrograms lining up with each other suggests typical AVNRT (Figure 4). One must still rule out a septal bypass tract, though, before a definitive diagnosis can be made. For more information, please visit: www.acp-online.org