What are chordae tendineae?

Chordae Tendineae: Anatomy and Function in Heart Valve Mechanics

Chordae tendineae are strong, fibrous cord-like structures that connect heart valve leaflets to papillary muscles, preventing valve prolapse during systole and maintaining proper cardiac function. 1

Anatomical Structure and Location

The chordae tendineae are critical components of the atrioventricular heart valves (mitral and tricuspid valves). They have the following characteristics:

• Composition: Primarily made of collagen and elastic fibers 2
• Location: Connect from papillary muscles to the ventricular side of valve leaflets 1
• Primary function: Prevent leaflets from prolapsing (swinging back) into the atrial cavity during systole 2

Classification of Chordae Tendineae

Chordae tendineae can be classified in multiple ways based on:

1. Origin:

   • Apical pillar chordae (from apex of papillary muscle)
   • Basal pillar chordae (from base of papillary muscle) 3

2. Insertion point on leaflets:

   • Marginal chordae (attach to free edge)
   • Rough zone chordae (attach to ventricular surface of rough zone)
   • Free zone chordae 3

3. Branching pattern:

   • First order chordae (no branching)
   • Second order chordae (branched) 3
   • Straight, branched-fan shaped, spiral, or irregular-web chordae 3

4. Structure:

   • Tendinous chordae (most common)
   • Muscular chordae (found in approximately 14% of cases)
   • Membranous chordae (found in approximately 6% of cases) 3

Role in Mitral Valve Function

In the mitral valve apparatus, the chordae tendineae are part of a complex system that includes:

• The saddle-shaped mitral annulus
• The multiscalloped and indented leaflets
• The papillary muscles
• The left ventricular wall attachments 1

The anterior mitral leaflet has a larger radial surface and attaches to about one-third of the annular circumference, while the posterior leaflet has a larger circumferential attachment (two-thirds of the annulus) 1. The chordae tendineae connect these leaflets to the papillary muscles, creating a functional unit.

Clinical Significance

Dysfunction of the chordae tendineae can lead to significant cardiac problems:

• Mitral valve prolapse: When chordae are elongated or ruptured, allowing leaflets to prolapse into the left atrium 1
• Mitral regurgitation: Can result from chordal rupture, often secondary to myocardial infarction, endocarditis, or degenerative disease 1
• Surgical considerations: Preservation of chordae tendineae during mitral valve replacement may better preserve postoperative left ventricular function compared to conventional replacement techniques 3

Pathological Implications

Abnormalities in chordae tendineae can contribute to various cardiac conditions:

• Congenital mitral stenosis: May involve shortened and thickened chordae tendineae, obliteration of interchordal spaces, and abnormal chordal insertions 1
• Secondary mitral regurgitation: Can result from abnormal tethering geometry due to left ventricular dysfunction and enlargement 1
• Muscularized chordae: A rare variant where muscular fibers extend from the papillary muscle to the valve leaflet, potentially disrupting valve closure mechanics 2

Understanding the complex anatomy and function of chordae tendineae is essential for proper evaluation and treatment of valvular heart diseases, particularly those involving the mitral and tricuspid valves.