What characterizes sinus bradycardia?

Sinus bradycardia is characterized specifically by a heart rate that is less than 60 beats per minute (bpm). This condition arises from the sinus node, which is responsible for initiating the electrical impulses that regulate heartbeats, firing less frequently than normal.

Additionally, in sinus bradycardia, despite the lower heart rate, the rhythm remains regular, and the electrical activity originating from the sinus node can still be seen, often with the presence of normal P waves on an electrocardiogram (ECG). This differentiates it from other conditions that might cause a slow heart rate, where the sinus node may not be functioning properly, leading to more erratic rhythms or absent P waves.

Understanding the normal ranges for heart rates is crucial; a heart rate exceeding 100 bpm would indicate tachycardia rather than bradycardia. Regular rhythms typically correspond with other diagnoses, and intermittent or absent P waves suggest different arrhythmias instead of sinus bradycardia. Thus, the hallmark of sinus bradycardia is indeed a heart rate that falls below 60 bpm, aligning with its definition and clinical significance.