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Topic

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Coronary sinus

The coronary sinus is the main venous channel of the heart, located in the posterior atrioventricular groove on the diaphragmatic surface of the heart. It drains most of the venous blood from the myocardium into the right atrium. The coronary sinus is about 2–3 cm in length and 8–15 mm in diameter, receiving tributaries including the great cardiac vein, middle cardiac vein, small cardiac vein, posterior vein of the left ventricle, and oblique vein of the left atrium. It opens into the right atrium between the inferior vena cava (IVC) orifice and the tricuspid valve, guarded by the Thebesian valve.

Synonyms

  • Main cardiac vein

  • Sinus coronarius

  • Coronary venous trunk

Function

  • Collects venous blood from the myocardium

  • Returns deoxygenated blood to the right atrium

  • Plays a key role in coronary venous circulation

  • Serves as an access route for cardiac pacing leads, ablation catheters, and retrograde cardioplegia

Venous Drainage

  • Coronary sinus itself drains directly into the right atrium

  • Tributaries:

    • Great cardiac vein (from anterior interventricular groove)

    • Middle cardiac vein (from posterior interventricular groove)

    • Small cardiac vein (from right margin of heart)

    • Posterior vein of the left ventricle

    • Oblique vein of the left atrium

MRI Appearance

T1-weighted images:

  • Coronary sinus lumen appears signal void (black) due to fast blood flow

  • Surrounding myocardium shows intermediate signal intensity

  • Fat around the atrioventricular groove appears hyperintense, outlining the vessel

T2-weighted images:

  • Lumen also shows signal void from flow

  • Perivascular edema or adjacent pathology appears hyperintense

  • Useful for evaluating thrombosis or extrinsic compression

STIR (Short Tau Inversion Recovery):

  • Suppresses pericardial fat, improving visualization of edema or inflammatory changes near the coronary sinus

  • Thrombosed coronary sinus may appear hyperintense due to stagnant blood or clot

T1 Post-Contrast (Gadolinium-enhanced):

  • Lumen enhances strongly with contrast (bright)

  • Allows assessment of patency, narrowing, or anomalous connections

  • Helpful for detecting coronary sinus atresia, stenosis, or anomalous pulmonary venous drainage

CT Appearance

Non-contrast CT:

  • Coronary sinus appears as a tubular soft tissue density structure in the posterior atrioventricular groove

  • Surrounded by fat and myocardium, may be difficult to distinguish without contrast

Contrast-enhanced CT (CT Angiography):

  • Coronary sinus is opacified brightly with contrast, easily identified in the posterior atrioventricular groove

  • Clearly shows size, tributaries, and entry into the right atrium

  • CT is excellent for evaluating dilatation (as in right heart failure), thrombosis, or anomalous venous connections

CT Image

Coronary sinus anatomy CT axial image -img-00000-00000

MRI image

Coronary sinus MRI axial image