Abbreviated AVNRT, this tachycardia is a re-entrant circuit within the AV node that results in a regular narrow complex (unless there is aberrant conduction) tachycardia, with rate 140-240/min. The atrium and ventricle are activated “in parallel” and retrograde atrial activation results in negative P-waves in the inferior leads (II, III and aVF). P-waves can be hidden inside the QRS complex or slightly deform the terminal part of the QRS complex such that they are visible as a “pseudo R-prime” in lead V1 or as a “pseudo S-wave” in the inferior leads.
