The spatial position of the RAV
The number of detected leaflets in the RAV was found to affect the relative position of the valve components. The supero-septal commissure was located on the septal side of the right atrium in proximity to the apex of Koch’s triangle and its location was the most stable point within the RAV circumference. Its position remained unchanged when comparing the 3- and 4-leaflet heart valves (Table 1, p > 0.05). In all examined hearts, the supero-septal commissure was located on the left-superior side of the ostium of the coronary sinus (Figure 1). The supero-septal commissure was never present within the vestibule of the right atrial appendage. This contrasted with the location of the supero-mural commissure which was always found in the vestibule’s middle sector. We observed a strong positive correlation between the length of the supero-septal commissure and the distance between the commissure and the ostium of the coronary sinus (r = 0.51, p < 0.001). No association was detected between the distance from the commissure to the ostium of the coronary sinus and the septal leaflet length (r = 0.12, p = 0.31).
The location of commissures found within the infero-mural aspect of the RAV annulus (the muro-septal and the infero-septal commissures) varied considerably, not only between different RAV configurations, but also between individual hearts with the same number of RAV leaflets. In the 3-leaflet heart valves, the muro-septal commissure was located further away from the ostium of the coronary sinus than the infero-septal commissure in the 4-leaflet configuration (16.1 ± 9.0 vs. 7.7 ± 6.3 mm, p < 0.001). The opposite trend was observed for the commissure’s distance to the terminal crest (5.8 ± 9.4 vs. 13.5 ± 6.4 mm, respectively; Table 1, p < 0.001). The location of the muro-septal commissure differed significantly: in 52.2% of specimens it was located in the area of the cavo-tricuspid isthmus (situated between the ostium of the coronary sinus and the terminal crest); in 9.0% of hearts it was situated at the level or to the left of the ostium of the coronary sinus; in 17.9% it was at the level of the terminal crest, and in the remaining 20.9% of cases it was found within the vestibule of the right atrial appendage (Figure 3). Additionally, there was a positive correlation between the segment from the muro-septal commissure to the terminal crest and the superior leaflet length (r = 0.32, p = 0.008). Meanwhile, this same segment had a negative correlation with septal leaflet length (r = -0.38, p = 0.001).
In 4-leaflet RAVs, the infero-septal commissure was predominantly located in the cavo-tricuspid isthmus area (81.8% of cases). It was never located within the area of the vestibule of the right atrial appendage. In the remaining 12.1% of hearts, the commissure was located at the level of the ostium of the coronary sinus while in 6.1% of cases, it pointed towards the septal direction. The spatial position of the infero-septal commissure in the 4-leaflet valve was influenced by the length of the septal leaflet (there was a positive correlation with the commissure’s distance to the ostium of the coronary sinus [r = 0.51, p = 0.03] and a negative correlation with the commissure’s distance to the terminal crest [r = -0.37, p = 0.03]). The infero-mural commissure was always located within the area of the right atrial appendage vestibule.
The relative positions of the components of the RAV were not affected by the donors’ age, sex or any other anthropometric features (weight, height, BMI).