In Vitro Characterization of the Mechanisms Responsible for Functional Tricuspid Regurgitation

Abstract

Background-Functional tricuspid regurgitation (TR) is increasingly recognized as a source of morbidity. Current repair strategies focus on annular remodeling because annular dilatation is common in patients with TR. Although papillary muscle (PM) displacement is recognized in functional mitral regurgitation, its role in TR is less well characterized. The objective of this in vitro study was to further clarify the mechanisms by which TR occurs as an effect of annular dilatation and PM displacement. Methods and Results-Porcine tricuspid valves (nϭ16) were studied in an in vitro right heart simulator. The valve dynamics were quantified with isolated annular dilatation starting with a normal annular size (6 cm 2 ) and incrementally dilated up to 100%, isolated PM displacement, and a combination of the 2. All valves lost competence at 40% dilatation, resulting in a TR of 7.9Ϯ3.4 mL (PՅ0.05) compared with baseline and central residual leaflet length of 0.5Ϯ0.2 cm. Multidirectional displacement of the anterior and posterior/septal PMs and all PMs significantly (PՅ0.05) increased TR, with normal annular area. Malcoaptation was observed where the 3 leaflets joined with all significant levels of TR. The anterior leaflet had the greatest percent change in residual leaflet length, whereas PM displacement caused a reduction in residual leaflet length for the septal leaflet for all conditions. Conclusions-This study shows that although annular dilatation alone leads to TR, isolated PM displacement can also cause TR; annular remodeling strategies should be tailored in the setting of severe PM displacement. (Circulation. 2011;124:920-929.)

Prognostic Value of Preoperative Right Ventricular Geometry and Tricuspid Valve Tethering Area in Patients Undergoing Tricuspid Annuloplasty

“…13 Failure of any 1 of these structures during TA will cause residual TR and increase the subsequent risk for adverse events. Similar to mitral regurgitation, 18 an altered RV geometry displaces TV papillary muscle and position for chordae insertion, leading to inadequate leaflet coaptation, which closely correlates with the severity of TR.…”

“…12,13 The TV tethering area is also associated with postoperative TR, which may subsequently affect clinical outcome. 14 The importance of these parameters as determinants of outcome in patients undergoing TA is unknown.…”

The Effects of a Three-Dimensional, Saddle-Shaped Annulus on Anterior and Posterior Leaflet Stretch and Regurgitation of the Tricuspid Valve

“…The valves were excised, preserving the valvular and sub-valvular components: annulus, leaflets, chordae tendineae, and PMs as detailed in previously published TV in vitro studies. 23 As there were multiple posterior PM heads and often times a fused septal PM, care was taken to excise tissue with all chordal insertions near each PM.…”

“…2) to simulate physiologic hemodynamic conditions. 23 The rods were used to achieve a normal PM configuration and were subsequently displaced to mimic PM positions which result from ventricular dilatation. For this study, PM displacement was simulated by displacing the anterior PM (APM) laterally and apically, and both the posterior (PPM) and septal (SPM) PMs together, laterally, anterior/posteriorly and apically.…”

“…The role of annular dilatation and PM displacement have been demonstrated to have a significant impact on TR, through both in vivo 16,17 and in vitro investigations. 23 It is believed that the anterior PM is displaced with right ventricular dilatation, as it is located on the free wall; while the septal and posterior PM is displaced with left ventricular dilatation, since they are located on the septal wall.…”