Physiological determinants of tricuspid annulus size during the cardiac cycle: implications for tricuspid annulus sizing by three-dimensional echocardiography

Purpose: Transthoracic 3D echocardiography (3DE) allows an unparalleled opportunity for quantifying the dynamic changes of the tricuspid annulus (TA). Accordingly, our aims were: (I) to assess the determinants of TA size during cardiac cycle in healthy subjects; (II) to propose an approach and timing for TA sizing using 3DE. Methods: In 50 healthy volunteers (45+14yrs, range 18-74, 27males, withnorisk factors, symptoms, signs or history of cardiovascular disease and on no medication), a fullvolume dataset of the right ventricle (RV) containing the tricuspid valve (TV) was acquired (Vivid E9,GEHealthcare).TAdiameters (septo-lateral, SL; antero-posterior, AP)and areas were measured on multiplanar images (Flexi-slice, EchoPac BT12, GE Healthcare) at 5 time points during the cardiac cycle: OS (onset of systole, at TV closure); MS (midsystole); ES (end-systole); ED (onset of diastole); LD (late diastole, after the P wave). RV volumes and ejection fraction (EF) were analyzed with commercial software (4D RV analysis, TomTec, D). Results: Temporal resolution of the 3D datasets was 32+4 vps (range 24-53). TA areas were more closely correlated with RV volumes and body surface area (BSA) than with either SL or AP diameters. TA areas increased during systole from OS (3.9+0.6 cm2/ m2) to ES (4.9+0.8 cm2/m2) and reached its largest area in LD (6.7+1.0 cm2/m2). All 5 TA areas were correlated with BSA (r range 0.57-0.62) and RV volumes (r ranges 0.53- 0.60 for end-diastolic volume and 0.43-0.50 for end-systolic volume, p,0.0001 for all). Indexed TA areas were not related to either age or gender. With multivariable analysis, both RVend-diastolic volume and BSA determined TA areas during systole and early diastole, while TA area at LD and at OS were independently related with BSA only. Conclusions: In healthy subjects, the main determinants of TA size are RV volume and BSA. The largest TA area occurs at LD and is independently related with BSA only. Therefore, normative values should be based on TAareas measured atLDand indexed forBSA. However, the rapid change in TA areas occurring from LD to OS underscores the importance of adequate temporal resolution of 3DE data sets for reliable TA measurements