What happens if the SA node fails?

As a medical professional with expertise in cardiology, I can explain the consequences of SA node failure. The SA (sinoatrial) node is often referred to as the heart's natural pacemaker. It generates electrical impulses that regulate the heartbeat. If the SA node fails, it can lead to a condition known as sick sinus syndrome. When the SA node fails to function properly, it may not send the electrical signals at the right time or with the correct regularity. This can result in a variety of symptoms, including: 1. Bradycardia: An abnormally slow heart rate, which can lead to fatigue, shortness of breath, dizziness, or fainting. 2. Tachycardia: A rapid heart rate that may occur in bursts, causing palpitations or a fluttering feeling in the chest. 3. Heart block: A condition where the electrical signals are blocked from reaching the ventricles, leading to a slower than normal heart rate. Treatment for SA node failure typically involves the use of medications to regulate the heart rate. In more severe cases, a pacemaker may be implanted to provide a regular electrical impulse to the heart, ensuring it beats at a normal rate.

Although the SA node is the natural pacemaker causing the heart to beat at a rate of 60-100 bpm normally, if this fails the others can take up this work usually the AV node then the Purkinje system and Bundle branches. This sequence is because of the natural rate these tissues beat at.