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Normal Sinus Rhythm

Image 2 of 2 in Series "Atrioventricular Nodal Reentrant Tachycardia (AVNRT)"

Description

A second ECG in the same patient demonstrates return to a normal heart rate of ~55 bpm and restoration of normal sinus rhythm as evidenced by consistent rhythm, p-waves preceding each QRS complex, and PR intervals <210 ms. Retrograde p-waves are absent. Note that Q waves continue to persist in lead III and QS complexes in lead aVF, which support the diagnosis of an old inferior infarct.

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This image is part of the series "Atrioventricular Nodal Reentrant Tachycardia (AVNRT)"

Other images in this series

AV-Nodal Reentrant Tachycardia

by: Charlotte M. Greenway; Joe B. Calkins, Jr., M.D.

This ECG demonstrates tachycardia at a rate of ~135 bpm and an absence of p-waves preceding each QRS complex, indicating that the patient is not in sinus rhythm. However, R'-like waves are visible in lead V1 and pseudo-S waves are noted in inferior leads II, III, and aVF, all of which represent retrograde, inverted p-waves. These findings in conjunction with short R-P intervals support a diagnosis of typical AV-Nodal Reentrant Tachycardia in which electrical activity passes retrograde from the ventricles to the atria via an accessory path through the AV node. This causes a positive deflection in lead V1 and negative deflections in inferior leads. ¬¬Note that Q waves are present in lead III and QS complexes in lead aVF, which suggest the presence of an old inferior infarct.