Sinoatrial Node (SA Node) — ECG/EKG Terminology

Definition: The natural pacemaker of the heart, located in the right atrium. It generates electrical impulses that set the heart rate, normally 60-100 beats per minute.

Key Facts

• Located in the upper right atrium
• Fires automatically at 60-100 beats per minute
• Sets the pace for the entire heart
• If it fails, backup pacemakers take over at slower rates

ECG Connection: When the SA node controls the rhythm, we call it "sinus rhythm"—the normal, healthy rhythm you'll see most often.

Why It Matters: If P waves disappear or change shape, you'll suspect the SA node is no longer leading—a critical finding to report.