koronarsinus

Koronarsinus, or coronary sinus in English, is a large venous channel located on the posterior surface of the heart. It collects blood from most of the cardiac veins and returns it to the right atrium, playing a central role in the drainage of the heart muscle.

The coronary sinus runs within the posterior atrioventricular groove (the coronary sulcus) and opens into the right atrium through the coronary sinus ostium. This ostium is situated on the posteroinferior wall of the right atrium, between the openings of the inferior vena cava and the tricuspid valve.

Tributaries of the coronary sinus include the great cardiac vein (the main venous drainage of the left heart), the middle cardiac vein, the small cardiac veins, the left marginal vein, and other posterior veins. Through these connections, the coronary sinus collects the majority of the venous blood from the myocardium, especially from the left atrium and left ventricle, before delivering it into the right atrium.

Embryology and variations: the coronary sinus develops from the left horn of the sinus venosus. Variants can include a persistent left superior vena cava that drains into the coronary sinus, which may cause dilation of the sinus. Clinically, the coronary sinus is a landmark in imaging and procedures; it can serve as an access route for certain electrophysiology interventions and for placing left ventricular pacing leads in cardiac resynchronization therapy.