Thebesian valve

The coronary sinus is bounded posteriorly by the Thebesian valve joining with the Eustacian ridge from the inferior vena cava to become the tendon of Todoro, anteriorly by the tricuspid annulus, and inferiorly by the inferior vena cava (Fig. 5.1). The coronary sinus typically courses posteriorly and paral-lelly to the mitral annulus. The diameter of the coronary sinus can be quite variable and commonly has a prominent Thebesian valve over its orifice. This venous valve is often fenestrated and can occasionally impede placonent of long sheaths deeply within the main body of the coronary sinus. Additionally, within the mid-body if the coronary sinus, venous valves are often present, the most prominent is the venous valve of Vieussens, located at the junction of the vestigial remnant of the vein of Marshall and the origin of the great cardiac... 

Fig. 5.1 Anatomy of the Medial Floor of the Right Atrium. To view the medial aspect of the floor of the right atrium, the anterosuperior portion of the tricuspid valve (TV) was resected. The Thebesian valve (ThV) of the coronary sinus (CS), joins posteriorly with the Eustacian valve (EuV) of the inferior vena cava (IVC). In the close-up view, small fenestrations (E) can be seen within the ThV. These fenestrations can impede placement of a long vascular sheath within the coronary sinus if a guide wire were placed through them.

Fig. 5.7 An Attain Prevail Catheter (Medtronic, Inc), This deflectable 7Fr catheter has a tapered (to 4Fr) soft tip (inset) that can be placed over a 0.035 in. guidewire and facilitate passage of a larger sheath through a stenosis or fenestration of the Thebesian valve (as seen in Fig. 5.1).

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