Sinoatrial Node Dynamics: Clinical Relevance and microRNA-Based Modulation of Pacemaker Activity.

The sinoatrial node (SAN) functions as the primary pacemaker of the heart, initiating rhythmic electrical impulses that govern cardiac contraction. It consists of specialised pacemaker cells located between the superior vena cava and the right atrium, supported by a paranodal region that contributes to rhythm stabilisation and may serve as a secondary pacemaker during dysfunction. This review describes the structural organisation and molecular regulation of the SAN, with particular focus on the role of HCN4 ion channels and the influence of the microRNA miR-486-3p in modulating pacemaker activity. Understanding this relationship may support the development of novel therapeutic strategies for managing conditions such as sinus tachycardia, offering potential alternatives to existing pharmacological approaches.