Sinus Node

**Sinus nodes** are cardiomyocyte fibers within the walls of the atria of the heart that produce impulses to coordinate heart contractions. These impulses are generated spontaneously or by electrical signals that excite the fibers, or impulses or hyperintensity waves as they interact with each other and with other elements of the heart. Sinus activity can be identified by its unique R wave on the ECG. As soon as the impulses at the sinus node reach the lower chamber of the heart (ventricle), the heart begins to contract.

The sinus node primarily maintains atrial depolarization