AEMCA Practice Exam

What characterizes a junctional rhythm?

1. Rapid heart rate with visible P waves

2. P waves that do not appear or are inverted

3. Regular rhythm without QRS complexes

4. High amplitude P waves

The correct answer is: P waves that do not appear or are inverted

A junctional rhythm is characterized by the presence of P waves that may be inverted, absent, or occurring after the QRS complex, which is indicative of the rhythm originating from the atrioventricular (AV) junction rather than from the sinoatrial (SA) node. In junctional rhythms, the junction serves as the pacemaker for the heart. This can result in the P waves being inverted when they appear in lead II or sometimes not appearing at all. Understanding the typical features of a junctional rhythm helps differentiate it from other types of rhythms. For instance, in a rapid heart rate with visible P waves, the rhythm is likely originating from the SA node or an atrial focus, which would not align with junctional characteristics. A regular rhythm without QRS complexes would suggest a lack of ventricular depolarization, which is not consistent with junctional rhythms where QRS complexes are usually present. Lastly, high amplitude P waves are more suggestive of conditions such as atrial enlargement rather than the inverted or absent P waves seen in junctional rhythms.