Background: The tricuspid valve annulus (TVA) is a complex three-dimensional structure that is incompletely understood. Three-dimensional transoesophageal echo (TOE) provides us with the opportunity to examine this structure in detail.
Methods and results: Fifty patients were included, divided into two groups: controls (n = 20), and dilated right hearts (DRH, n = 30). Three-dimensional zoom images of the TVA were acquired using an iE33 machine and X7-2t transducer. Antero-posterior (AP) diameter, septo-lateral (SL) diameter, area, circumference, and height were measured at 6 points of the cardiac cycle adapting commercially available software designed for assessing the mitral valve (MVQ, Philips). The eccentricity ratio was calculated as AP/SL. The tricuspid annular area decreases during systole in both groups, and is greatest in mid-diastole. The area is significantly larger in the DRH group (mean 1566 mm(2) DRH vs. 1097 mm(2) controls; P < 0.01). The SL diameter increases proportionately more in the DRH group, resulting in a more circular orifice and lower eccentricity ratios (eccentricity ratio mean 1.01 DRH vs. 1.24 controls; P < 0.01). The dynamic diastolic to systolic change in the SL diameter is lost in patients with DRH, contributing to the more circular TVA orifice throughout systole.
Conclusion: Three-dimensional TOE allows us to examine the TVA in great detail. In patients with DRH, the TVA dilates in a SL direction, resulting in a more circular orifice. The dynamic changes of the TVA are lost in patients with DRH, potentially contributing to functional tricuspid regurgitation.