From the Guidelines

The coronary sinus is a collection of veins that return deoxygenated blood from the myocardium to the right atrium.

It is located on the posterior surface of the heart and plays a crucial role in cardiac anatomy and function 1.
The coronary sinus receives blood from several venous tributaries, including the anterior, anterolateral, lateral, postero-lateral, and posterior (middle cardiac vein) branches 1.
Knowledge of the patient's coronary venous tree is essential in planning certain cardiac procedures, such as cardiac pacing and cardiac resynchronization therapy 1.
The coronary sinus is also relevant in the context of mitral annuloplasty, where devices are placed within the coronary sinus to reduce mitral regurgitation 1.
Injury to the coronary sinus is considered a cardiac structural complication and can have significant clinical implications 1.

From the Research

The coronary sinus is the main cardiac vein, playing a crucial role in various diagnostic and therapeutic procedures 2.
It is located in the heart and has a complex anatomical structure, with its position being important for many electrophysiologic procedures 2.
The coronary sinus has tributaries, including the great cardiac vein, left marginal vein, and small cardiac vein, which were studied in adult human cadaveric hearts 3.

The coronary sinus is important for procedures such as biventricular pacemaker implantation, left-sided accessory pathway evaluation and ablation, and mapping of the coronary sinus 2.
The coronary sinus musculature and its connections to the left and right atrium and to the left ventricle have been identified as playing a role in various types of supraventricular arrhythmias 2.
Coronary sinus dilatation is a sign of impaired right ventricular function in patients with heart failure, and can be used as a novel echocardiographic marker 4.

Considerable variations in the diameter of the coronary sinus ostium were observed in a study of 100 adult human cadaver hearts 5.
The presence and morphology of the Thebesian valve, which covers the coronary sinus ostium, can vary, with some hearts having no valve or a valve that completely occludes the ostium 5.
Congenital abnormalities of the coronary sinus, such as an unroofed coronary sinus or anomalous pulmonary venous connection to the coronary sinus, can be identified using imaging techniques like CT and magnetic resonance imaging 6.