Morphology of the Human Tricuspid Valve

Abstract

The morphology of 50 normal tricuspid valves was studied. The surface of the leaflets was divided into three zones: (1) the rough zone, into which most of the chordae tendineae are inserted, (2) the basal zone, and (3) the clear zone, which lies between the rough and basal zones.Five types of chordae were distinguished by their morphology and mode of insertion: fan-shaped, rough zone, basal, free edge, and deep chordae. The last two types are unique to the tricuspid valve.If fan-shaped chordae, used to define the commissures between the leaflets, are absent, other landmarks may be used for commissural definition. Once defined, all tissue between the commissures was regarded as part of the anterior, posterior, or septal leaflet. The recognition that the free edges of the anterior and septal leaflets contain notches, that rough zone chordae insert into them, and that the posterior leaflet has scallops further aids identification of a leaflet's components. Thus, structures formerly regarded as accessory leaflets were incorporated into one of the three leaflets.RECENTLY, we have reexamined the morphology of the mitral valve and have been able to establish a better clinicopathologic correlation in various types of mitral valve abnormality. By identifying the specific fan-shaped chordae tendineae attached to the mitral valve, we were able to delineate the commissural areas clearly and to divide the valve into anterior and posterior leaflets. We were, thus, also able to identify the clefts of the posterior leaflet and to distinguish them from the true commissures.1 2 This definition of mitral valve anatomy eliminates the need to postulate accessory leaflets of the mitral valve. It proved valuable in enhancing clinicopathologic understanding of the syndrome of mitral regurgitation due to prolapse of the posterior leaflet.3

In Vitro Characterization of the Mechanisms Responsible for Functional Tricuspid Regurgitation

“…In contrast to the anterior leaflet, the septal leaflet experienced little change in RLL as an effect of dilatation. This may be explained by previous studies that have reported the large number of chordae insertions to the septal leaflet from the septum 24 and the possibility for restricted motion. Although it is accepted that annular dilatation may result in TR, it is not the only mechanism.…”

“…We believe that this is because the anterior leaflet attempts to compensate for the increase in the orifice area created by dilatation of the annulus by reaching to cover it. Multiple studies have reported the anterior leaflet to be the longest and largest in area compared with the posterior and septal leaflets, 24,26 which may be the body's attempt to compensate for annular dilatation up to a certain level. In contrast to the anterior leaflet, the septal leaflet experienced little change in RLL as an effect of dilatation.…”

“…With this increased mobility, the coaptation line of the 3 leaflets was more toward the center of the annulus; thus, the septal leaflet covered more of the orifice but was not long enough to do so because it is the shortest leaflet, 24,26 and this resulted in a central zone of malcoaptation ( Figure 8B). Although numerous PM displacements were investigated, severe displacement, with the APM, S/PPM, and all PMs displaced in multiple directions simultaneously, was the only condition that resulted in significant TR.…”

“…The intact leaflet height and width were then measured with the use of a flexible ruler to confirm appropriate size, as reported previously for human valves. 13,24,26 Further selection criteria were based on chordae insertions and PMs in 3 groups (anterior, posterior, and septal) to allow for fixation in the simulator. Selected valves were excised with the annulus, leaflets, chordae, and PMs intact.…”

Ebstein's Anomaly—An Overview

“…The first diagnostic criteria for Ebstein's anomaly using a multi-crystal two-dimensional system was defined by Hagan in 1974 [33] and they were able to recognize the apical displacement of the septal tricuspid leaflet and an elongated anterior tricuspid leaflet with increased excursion. The septal leaflet of the tricuspid valve attaches chiefly to the ventricular septum, but part of its basal attachment is to the posterior wall of the right ventricle [34] and it normally exhibits a slight but distinct apical displacement of its basal attachment to the central fibrous body compared to the mitral valve. The distal displacement of septal origin of tricuspid valve seems to be the best echocardiographic criterion as the characteristic sign for Ebstein's anomaly and the degree of maximal displacement in normal hearts varies considerably with a mean difference of approximately 6 mm with mitral valve.…”