Sick Sinus Syndrome

The sinoatrail node (SAN), the dominant pacemaker in the heart, was originally described by Keith et al. in 1907 [1]. The SAN is a subepicardial structure located at the junction of the right atrium and the superior vena cava [1]. The SAN spontaneous firing activity is not completely understood. Two predominant mechanisms are proposed to serve as the initiation of the sinus activity: The If channels (sodium and potassium ionic currents) and …