Which rhythm is typically generated by the AV node with a pace around 40-60 bpm?

Which rhythm is typically generated by the AV node with a pace around 40-60 bpm?

• A. Atrial tachycardia
• B. Junctional rhythm
• C. Sinus tachycardia
• D. Ventricular tachycardia

Answer: (B)

When the heart’s pace is coming from the AV node, it’s a slower, backup rhythm. The AV node can pace the heart at about 40–60 beats per minute, which is slower than the SA node. A rhythm that originates in the AV node is called a junctional rhythm. Key features include a rate in the 40s to 60s and a narrow QRS complex (since the ventricles are still activated through the normal His-Purkinje pathway). P waves may be absent or may appear before, during, or after the QRS, and their shape can be inverted depending on the exact timing of atrial depolarization relative to ventricular depolarization. This matches a rhythm generated around 40–60 bpm, so the junctional rhythm is the best fit. Atrial tachycardia would typically show a faster rate with distinct atrial activity. Sinus tachycardia starts in the SA node and usually runs faster than 100 bpm. Ventricular tachycardia originates in the ventricles and typically has a wide QRS complex, not a slow AV-nodal pace.

When the heart’s pace is coming from the AV node, it’s a slower, backup rhythm. The AV node can pace the heart at about 40–60 beats per minute, which is slower than the SA node. A rhythm that originates in the AV node is called a junctional rhythm. Key features include a rate in the 40s to 60s and a narrow QRS complex (since the ventricles are still activated through the normal His-Purkinje pathway). P waves may be absent or may appear before, during, or after the QRS, and their shape can be inverted depending on the exact timing of atrial depolarization relative to ventricular depolarization.

This matches a rhythm generated around 40–60 bpm, so the junctional rhythm is the best fit. Atrial tachycardia would typically show a faster rate with distinct atrial activity. Sinus tachycardia starts in the SA node and usually runs faster than 100 bpm. Ventricular tachycardia originates in the ventricles and typically has a wide QRS complex, not a slow AV-nodal pace.