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 ...

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 ...

In a normal heart rhythm, your heart beats in a steady, even way. The upper part of your heart (atria) squeezes and pushes blood to the lower part (ventricles), pumping blood and oxygen out to the ...