Which condition indicates a sinus rhythm with a heart rate less than 60 BPM?

The condition that indicates a sinus rhythm with a heart rate less than 60 beats per minute (BPM) is bradycardia. Bradycardia is defined as a slower than normal heart rate and is characterized by a heart rate that falls below the threshold of 60 BPM. In the context of a sinus rhythm, it means that the electrical impulses originating from the sinoatrial (SA) node are still leading to an organized rhythm, but the rate at which the heart beats is reduced.

Bradycardia can be a normal finding in athletes or during sleep, where the heart adapts to lower demands. However, it can also indicate various underlying conditions, including aging, medication effects, or conduction issues within the heart, making its identification important in clinical practice.

Understanding this concept is crucial, especially in interventional radiology, where patient heart rates and rhythms can affect pre-procedural evaluations and post-procedural monitoring.