vieussens valve of the coronary sinus vieussens valve of the coronary sinus the vieussens valve of the coronary sinus is a prominent valve at the end of the great cardiac vein, marking the commencement of the coronary sinus. it is often a flimsy valve composed of one to three leaflets. it is present in 80-90% of individuals. it serves as an anatomical landmark. it is clinically important because it is often an obstruction to catheters in 20% of patients.