MORPHOLOGY OF CORONARY SINUS OSTIUM AND THEBESIAN VALVE

Ilakkiya Lingasamy*, Isai Vani N. and Aruna S.

ABSTRACT

The coronary sinus ostium in the right atrium is covered by endocardial tissue called the Thebesian valve, which can influence and cause difficulty in many cardiac procedures like cannulation and lead placements. The aim of this study is to measure the dimensions of coronary sinus ostium and Thebesian valve covering the ostium. Our study of 25 formalin fixed hearts showed the presence of Thebesian valve at an incidence of 76%. The shape of the Thebesian valve was also noted and semilunar type was found to be predominant with 42.10%, followed by remnant type. Out of the total hearts, 20% of specimens were more likely to cause obstruction, which includes fenestration and cord type. No specimen was found to have Thebesian valve completely obstructing the ostium. The mean transverse and craniocaudal diameter were significantly more in the hearts without Thebesian valve than the hearts with Thebesian valve. The dimensions of the Thebesian valves revealed the mean transverse diameter was minimum in remnant type (5.25mm) and maximum in fenestrated type (8.7mm). The minimum and maximum craniocaudal diameters of the valve were found in the remnant type (1.86mm) and the fold type (8.3mm) respectively. Knowing about the variations and careful evaluation of these diameters and Thebesian valve will be helpful for the surgeons to overcome the difficulties faced during interventional cardiac procedures.

Keywords: Thebesian valve, Coronary sinus ostium, Cardiac procedures.