What is the appearance of a junctional rhythm on an ECG?

A junctional rhythm on an ECG is characterized by specific features that arise due to the impulse being generated from the atrioventricular (AV) junction rather than the sinoatrial (SA) node. This is why inverted P waves or P waves that are buried within the QRS complex are the hallmark of this rhythm.

When the impulse originates from the AV junction, it may travel backward to the atria, which can lead to inverted P waves. This is seen in leads where the P wave normally appears positive in a sinus rhythm. Additionally, due to the simultaneous depolarization of the ventricles, the P waves may find themselves positioned just before or even completely obscured by the QRS complexes, illustrating the junctional nature of the rhythm.

The presence of regular P waves followed by QRS complexes would indicate a sinus rhythm or an atrial rhythm, which isn't characteristic of a junctional rhythm. Similarly, wide QRS complexes with tall T waves suggest a completely different mechanism of dysrhythmia, such as ventricular ectopy. A normal sinus rhythm would exhibit a distinct SA node origin with P waves consistently preceding QRS complexes.

Thus, the unique characteristics of P waves in relentless junctional rhythms—whether inverted, absent, or