Valve rings (fibrous skeleton) !
The valve rings form the heart's fibrous skeleton; they hold the valves in shape and insulate the atria from the ventricles electrically.
Official name: Fibrous rings of the heart valves
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What it is
Tough rings of fibrous tissue at the base of the valves, joined into the heart's 'skeleton'.
What it does
Hold the valves' shape and electrically insulate the atria from the ventricles, so the signal can only cross at the AV node.
Key facts
- Where
- Fibrous skeleton between atria and ventricles: mitral, tricuspid, aortic and pulmonary rings; right and left fibrous trigones
- Attaches
- Valve leaflets and cusps; atrial and ventricular myocardium
- Function
- Supports valve shape; electrically insulates atria from ventricles (AV bundle pierces right fibrous trigone)
Relations
- In front
- Pulmonary ring, the highest and most anterior, joined to the aortic ring by the conus ligament
- Behind
- Coronary sinus along the mitral ring, Circumflex artery in the left atrioventricular groove and right coronary artery around the tricuspid ring
- Below
- Ventricular muscle below and atrial muscle above; only the bundle of His crosses between them
How to find it
On the chest wall the rings lie on an oblique line behind the sternum: pulmonary highest, at the left 3rd sternocostal joint; aortic a little lower and medial; mitral behind the left half of the sternum at the 4th cartilage; tricuspid lowest, behind the sternum at the 4th space. Murmurs are heard downstream, at the auscultation areas.
On imaging
Echo measures annular diameters (tricuspid annular dilation guides repair) and TAPSE, the systolic movement of the lateral tricuspid annulus toward the apex, a measure of right ventricular function. CT measures the aortic annulus before transcatheter valves.
Common problems
- The mitral and tricuspid rings stretch when the heart enlarges, making the valves leak.
Treatment
- An annuloplasty ring sewn into the annulus is part of most valve repairs; TAVR valves are sized to the aortic annulus.
Clinical notes
- Mitral annular calcification, common in older people, can extend into the conduction system and complicates valve surgery
- Annuloplasty stitches near the trigones, the coronary sinus and the circumflex artery risk the conduction system and the coronary circulation
- Endocarditis abscess spreads through the fibrous skeleton toward the central fibrous body and can cause AV block
Development
Fibrous tissue from the atrioventricular groove and the cushions grows in and cuts the early muscle continuity between atria and ventricles; a strand of muscle left across it becomes an accessory pathway.
Related conditions
Test yourself
Think of the answer, then tap the question to see it.
Which structures form the central fibrous body of the heart?
The right fibrous trigone and the membranous septum; it is the strongest part of the cardiac skeleton.
What is the electrical role of the fibrous skeleton, and what normally crosses it?
It insulates the atria from the ventricles; only the bundle of His crosses, piercing the right fibrous trigone.
What causes Wolff–Parkinson–White pre-excitation, and where is it ablated?
An accessory pathway crossing the valve annuli outside the AV node; it is ablated at the annulus.
What shape is the mitral annulus, and what do repair rings restore?
Saddle-shaped, not flat; annuloplasty rings restore its size and shape.
What does TAPSE measure?
The systolic movement of the lateral tricuspid annulus toward the apex, a measure of right ventricular function.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Spanish (DeCS)
- Anillos fibrosos del corazón
- English (TA2)
- Fibrous rings of the heart valves
Sources: Anatomy, Thorax, Heart; Anatomy of the Human Body (20th ed.): Surface Markings of the Thorax (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain; Tratado de anatomía humana (9.ª ed.), tomo II, Libro IV Angiología, sección 1, capítulo 1: Corazón, artículos I–VI.
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Representative model, for educational purposes only.
