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

Abstract

Tricuspid regurgitation (TR) is present in trace amounts or more in 82-86% of the population and is greater than mild in 14% of the population. In severe cases, it can contribute to right heart failure and adversely affect mitral valve repair durability. One major cause of TR is the dilation of the tricuspid annulus, which alters the geometry of the annulus from a saddle-shape to a more planar profile. Another cause of TR is the displacement of the papillary muscles (PMs), which results from right ventricular dilation. The objective of this study was to identify the effect of a saddle-shaped annulus on native tricuspid leaflet stretch mechanics and TR. In addition, the effects of geometric alterations, including annular dilatation and PM displacement, on leaflet stretch was investigated. Fresh porcine tricuspid valves (TVs) (n = 8) were excised and sutured to an adjustable three-dimensional annulus plate (allowing for dilatation and saddle-shape) and three PM attachment rods. The valve was then placed in the in vitro Georgia Tech right heart simulator. Dual-camera photogrammetry, was used to quantify the stretch ratio experienced by the valve leaflets at peak systole for the following conditions: physiologically normal, 100% annular dilatation, displaced PMs, and a combination of annular dilatation and PM displacement. In addition, a saddle and flat annulus were implemented for each of the four conditions. PM displacement was simulated by displacing all PMs by 10 mm in all directions (laterally, apically, posteriorly/anteriorly). The physiologically normal condition-normal annulus area, saddle-shaped annulus with PMs in a normal position, was used as a control. The results showed that the posterior leaflet exhibited significantly (p ≤ 0.05) higher major and areal stretch ratios as compared to the anterior leaflet at peak systole for all conditions tested. No significant difference was seen in stretch when a flat annulus was compared to saddle for the anterior or posterior leaflet for normal or disease conditions. Investigation of the impact of disease found a significant increase (p ≤ 0.10) in stretch in the posterior leaflet with a combination of annular dilatation and PM displacement (2.01 ± 0.68) as compared to the normal condition with a saddle annulus (1.43 ± 0.20). In addition displacement of the PMs resulted in a significant (p ≤ 0.01) reduction in TR, although the actual volume reduced was minimal (1.2 mL). Stretch values were measured for the anterior and posterior leaflet under both physiologic and pathologic conditions for the first time. Further, these results provide an understanding of the effects of geometric parameters on valve mechanics and function, which may lead to improved TV repairs.

Total ellipse of the heart valve: the impact of eccentric stent distortion on the regional dynamic deformation of pericardial tissue leaflets of a transcatheter aortic valve replacement

“…Dual-camera stereophotogrammetry was used to acquire highspeed images of the TAVR leaflet and measure dynamic deformation, similar to previous experiments performed for native aortic and mitral valves [22,30] and BHV types [25]. Dynamic motion of the marker dots on the aortic side of the TAVR leaflets was captured at 500 frames per second using an image grabbing system (EPIX CL3SD, Buffalo Grove, IL, USA) with two high-speed cameras (Basler A504 K, Basler) orientated at 22.58 to the horizontal and 308 to the vertical, as shown in figure 2a,b.…”

“…where G 0 ab and G ab are components of the metric tensor in the deformed configuration and reference configuration, respectively [22,30,33].…”

“…The marker array on the leaflet surface was tracked from the stereo image rsif.royalsocietypublishing.org J. R. Soc. Interface 12: 20150737 pairs acquired using a previously developed automatic marker tracking algorithm in Matlab (Mathworks, Natwick, MA, USA) [22,30]. Using direct linear transformation (DLT), two-dimensional pixel coordinates of each marker dot from the stereo image pairs were reconstructed into three-dimensional space.…”

“…The aortic root assembly was connected to the Georgia Tech Left Heart Simulator (LHS), which has previously been used to simulate impaired and physiological haemodynamic conditions of aortic, mitral and TAVRs valves in an in vitro test set-up [22,29,30]. The pulsatile flow loop consisted of a fluid reservoir, a mechanical mitral valve, a bladder pump, an acrylic valve chamber, and compliance and resistance elements [22,29].…”

Tricuspid Annular Geometry: A Three-Dimensional Transesophageal Echocardiographic Study

“…To better understand the complex tricuspid annular structure, there have been a number of invasive animal studies or in vitro models. 16–18 In humans, the volumetric nature of the 3-dimensional (3D) data with transesophageal echocardiography (TEE) has the potential to allow a more comprehensive assessment of the tricuspid annulus. Ready availability of real-time 3D TEE (RT-3D TEE) already has provided a better geometric understanding of similar complex intracardiac structures, such as the mitral annulus.…”