What is underlying sinus rhythm?

Underlying sinus rhythm refers to the normal heart rhythm generated by the sinoatrial (SA) node, which is the heart's natural pacemaker. It is characterized by a consistent pattern of electrical impulses that result in a regular heartbeat, typically at a rate of 60 to 100 beats per minute. This rhythm is essential for maintaining effective blood circulation and is typically assessed through an electrocardiogram (ECG). Abnormalities in the underlying sinus rhythm can indicate various cardiac conditions.