Anatomy of the Tricuspid Valve

Introduction
The tricuspid valve complex consists of the annulus, leaflets, right ventricle, papillary muscles and chordae tendinae. The tricuspid valve lies between the right atrium and the right ventricle and is placed in a more apical position than the mitral valve. The tricuspid valve lies within the right trigone of the fibrous skeleton of the heart. The fibrous structure, called the annulus, provides a firm support structure for the tricuspid valve. The annulus separates the right atrium from the right ventricle. The annulus is less fibrous than other annuli and slightly larger than the mitral valve annulus. The tricuspid annulus is ovoid in shape.

 

Tricuspid Valve Complex
Tricuspid Valve Annulus
Tricuspid Leaflets
Chordae Tendinae
Right Ventricular Papillary Muscles
Right Ventricle

 
Fibrous Trigone of the Heart

The apical insertion of the tricuspid valve serves as a reliable indicator of the location of the tricuspid valve in deciphering valve orientation in congenital heart disease.

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ME 4CV 2D Image ME 4CV 2D Video
Tricuspid Valve Leaflets

The tricuspid valve has three leaflets which are thin and membranous with commissures that appear more like indentations than true commissures. The TV apparatus is similar to the mitral valve but has greater variability and thinner leaflets. The three leaflets are the anterior, septal and posterior leaflets, with the anterior and septal being larger than the posterior leaflet. Normal tricuspid valve annulus diameter is 28 ± 5 mm in the midesophageal 4 chamber view . The normal area of the tricuspid valve is 7-9 cm2 making it the largest of the four cardiac valves.

The septal leaflet has more support from the fibrous trigone than the anterior or posterior leaflet. Therefore, tricuspid regurgitation that is due to annular dilation, is usually due to the loss of copatation between the anterior and posterior leaflets.

The anterior and the septal leaflets are the largest leaflets and the posterior leaflet is smallest.

 

The septal leaflet of the tricupsid valve normal insertion point is less than 10-15 mm from the mitral valve annulus.

 
Base of the Heart

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TV SAX Image TV SAX VIdeo
Papillary Muscles and Chordae Tendinae

The three papillary muscles are the anterior, posterior and septal (also referred to as medial or conal) papillary muscles. The papillary muscles exhibit variability in size. The anterior and septal papillary muscles are the largest. The posterior papillary muscle is small and, at times, absent. The anterior papillary muscle has attachments to the moderator band. Each leaflet has chordal attachments to one or more papillary muscles.

The anterior and septal papillary muscle is larger than the posterior papillary muscles. (Corresponds to the tricuspid valve leaflets.)

 

 
Tricuspid Valve Anatomy

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Macerator Band Image Moderator Band Video

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Papillary Muscle Image Papillary Muscle Video

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Papillary Muscle Image Papillary Muscle Video

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Papillary Muscle Image Papillary Muscle Video
Conduction System

The conduction system is located near the base of the septal leaflet. The AV node is located near the septal leaflet as is the coronary sinus ostia. The coronary sinus is a posterior structure and lies adjacent to the commissure of the septal and posterior leaflets. The triangle of Koch and the tendon of Todaro serve as anatomic landmarks for the location of the AV node. The AV node lies in the apex of the triangle which is bounded by the septal leaflet anteriorly, the Tendon of Todaro posteriorly, the central fibrinous body (containing the Bundle of His) superiorly, and the coronary sinus inferiorly. Consequently suturing in this area can cause complete heart block.

When repairing the tricuspid valve, an open "C" ring avoids the necessity of suturing near the AV Node making complete heart block less likely.

 

 
AV Node Location