The sinus of your heart has nothing to do with your nose as you might guess; it’s a structure in the right atrium where blood ...

The sinoatrial (SA) node is the natural pacemaker of the heart. It generates electrical impulses that cause the heart’s chambers to contract, setting the heart rate. The SA node typically generates 60 ...

Sinoatrial exit block occurs when the action potential initiated by the sinoatrial node is inhibited or completely blocked before it is able to leave the SA node and reach the atrium, and thus no P ...

Junctional rhythm is an irregular heart rhythm that stems from a natural pacemaker in the heart known as the atrioventricular junction. The heart has several built-in pacemakers that help control its ...

Sick sinus syndrome (SSS) is a heart rhythm problem that affects your heart's natural pacemaker. You may develop symptoms of SSS like dizziness, fainting, and fatigue. Treatment may include lifestyle ...

A premature atrial contraction occurs when a focus in the atrium (not the sinoatrial node) generates an action potential before the next scheduled SA node action potential. There are four main ...

Having an accelerated junctional rhythm occurs when the atrioventricular node in your heart beats too quickly. It happens as a result of damage to your heart’s primary natural pacemaker. There’s no ...

A junctional escape rhythm is when the heartbeat starts in a different part of the heart than it should. This type of arrhythmia may not need treatment, but a doctor does need to investigate the ...