Chordae tendinea

Formation of vegetations may destroy valvular tissue, and continued destruction can lead to acute heart failure via perforation of the valve leaflet, rupture of the chordae tendineae or papillary muscle, or in the patient with PVE, valve dehiscence. Occasionally, valvular stenosis may occur. Abscesses can develop in the valve ring or in myocardial tissue itself. Even with resolution of the process, fibrosis of tissue with some residual dysfunction is possible. 

Valves and fibrous valve annuli, chordae tendineae... 

FIGURE 55.5 Schematic of the mitral valve showing the valve leaflets, papillary muscles, and chordae tendineae. 

The mitral (Figure 55.5) and tricuspid valves are similar in structure with both valves composed of four primary elements (1) the valve annulus, (2) the valve leaflets, (3) the papillary muscles, and (4) the chordae tendineae. The base of the mitral leaflets form the mitral annulus, which attaches to the atrial and ventricular walls, and aortic root. At the free edge of the leaflets, the chordae tendinae insert at multiple locations and extend to the tips of the papillary muscles. This arrangement provides continuity between the valve and ventricular wall to enhance valvular function. The valvular apparatus, or complex, requires an intricate interplay between all components throughout the cardiac cycle. 

FIGURE 55.6 Diagram of the mitral valve as a continuous piece of tissue. The posterior and anterior leaflets are indicated, as are the scallops, chordae tendineae, and papillary muscles. 

The mitral leaflet tissue can be divided into both a rough and clear zone. The rough zone is the thicker part of the leaflet and is defined from the free edge of the valve to the valve s line of closure. The term rough is used to denote the texture of the leaflet due to the insertion of the chordae tendineae in this area. The clear zone is thinner and translucent and extends from the line of closure to the annulus in the anterior leaflet and to the basal zone in the posterior leaflet. Unlike the mitral valve, the tricuspid valve has three leaflets (1) an anterior leaflet, (2) a posterior leaflet with a vciriable number of scallops, and (3) a septal leaflet. The tricuspid valve is larger and structurally more complicated than the mitral valve and the separation of the valve tissue into distinct leaflets is less pronounced than with the mitral valve. The surface of the leaflets is similar to that of the mitral valve however, the basal zone is present in all of the leaflets [Silver et al., 1971]. 

Lim, K.O. and Bouchner, D.R 1975. Mechanical properties of human mitral valve chordae tendineae variation with size and strain rate. Can. J. Physiol. Pharmacol 53 330-339. 

Silverman, M.E. and Hurst, J.W 1968. The mitral complex interaction of the anatomy, physiology, and pathology of the mitral annulus, mitral valve leaflets, chordae tendineae and papillary muscles. Am. Heart J. 76 399 18. 

Chordae tendineae, 55-8-55-9 Chou,C.,52-5,52-10 Choung, C.J., 57-4 Chow,A.Y, 35-2-35-3 Chronic electrical stimulation of the nervous system for functional disorders, 29-8-29-9... 

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