Coronary sinus

Last revised by Craig Hacking on 15 Sep 2021

The coronary sinus is the largest cardiac venous structure. It returns the majority of the blood supply for the left ventricle to the right atrium.

The coronary sinus courses along the posterior wall of the left atrium into the left atrioventricular groove. It normally drains into the right atrium. The ostium of the coronary sinus is partially covered by the Thebesian valve.

Veins draining into the coronary sinus are highly variable, but usually, include:

The coronary sinus develops from one of the two sinus horns of the sinus venosum. The other horn becomes part of the right atrium. The right venous valve of the sinus venosum develops into the thebesian valve and the Eustachian valve. For further detail see cardiac development.

  • the coronary sinus may act as a conduit between a persistent left superior vena cava and the right atrium
  • rarely, the coronary sinus may drain into the left atrium, causing a left-to-right shunt (or right-to-left in cases of right heart failure)

The coronary sinus may be involved in a number of different procedures or pathologic processes:

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Cases and figures

  • Figure 1
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  • Case 1: labeled 84
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  • Figure 2: venous development (Gray's illustrations)
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