Coronary sinus ostium: the key structure in the heart's anatomy from the electrophysiologist's point of view.

There are no research studies that comprehensively analyze, with computed tomography, the coronary sinus (CS) ostium with respect to its importance for some electrophysiological procedures paying special attention to the Thebesian valve (ThebV). Our aim was to evaluate the characteristic features of the CS anatomy, which can be useful for electrophysiologists using multislice computed tomography (MSCT). An additional aim was to create a tomographic classification of ThebV types. Included into the study were 150 patients (aged 59.7 ± 11.4; 105M) (43 with heart failure). Due to the suspicion of coronary artery disease, 64-slice MSCT (Toshiba, Aquilion 64) was performed in all patients. All measurements and the search for the ThebV were performed on multiplanar reconstructions in axial projection at 0.5-mm slice thickness. The average diameter of CS ostium was 14.2 ± 3.5 mm and the angle of entrance of the CS to the right atrium was 112° ± 11°. Seven variants of the ThebV were introduced and six of them were confirmed in this group. The following frequency of variants of ThebV was confirmed: E, 11.3%; D, 10.6%; A1, 8.7%; A2, 7.4%; C, 6.0%; B2, 2.0%. A statistically significant correlation between age and the size of CS ostium was found (r = 0.25; p < 0.05). It is possible to visualize and evaluate the CS including measurements and ThebV evaluation in MSCT. Six anatomical variants of the valve were found. MSCT can potentially provide valuable knowledge before the CS cannulation.