Variations in Thebesian valve anatomy and coronary sinus ostium: implications for invasive electrophysiology procedures.

Aims: The coronary sinus (CS) is a commonly cannulated structure in patients undergoing electrophysiology studies, catheter ablation of arrhythmias, implantation of resynchronization therapy devices and, more recently, percutaneous mitral valve repair. The advent of these procedures has led to a renewed interest in the anatomy of the coronary venous system including its various components. To improve our understanding of this structure, we studied the anatomy of the human CS, including the valve that guards its ostium, the Thebesian valve.

Methods And Results: In 75 randomly selected autopsied human hearts, we measured the transverse and craniocaudal dimensions of the CS ostium and characterized the shape, composition, per cent coverage, and attachment points of the Thebesian valve when present. Of the 75 hearts examined, 54 had organic heart disease including atherosclerotic coronary artery disease, left ventricular hypertrophy, dilated cardiomyopathy, rheumatic heart disease, infective endocarditis, and non-rheumatic valvular heart disease. A wide variety of Thebesian valve morphologies were seen, ranging from the absence of any valve to those where the valve was completely occluding the CS ostium. A Thebesian valve was present in the majority of the hearts examined (55/75 hearts-73%). The average transverse dimension of the CS ostium in hearts with Thebesian valves (7.3+/-2.8 mm) was significantly shorter than those without Thebesian valves (9.4+/-2.9 mm, P=0.005). Similarly, the average craniocaudal dimension of the CS ostium in hearts with Thebesian valves (7.9+/-2.7 mm) was also significantly shorter than those without Thebesian valves (9.3+/-2.9 mm, P=0.045).

Conclusion: Our study shows that some form of Thebesian valve is present in the majority of hearts (>70%). Of these, a significant minority (16%) had a valve morphology (covering >75% of the ostium, a fibrous, fibromuscular, or muscular composition, and devoid of fenestrations) that makes them a 'potentially complicating' structure interfering with the cannulation of the CS.