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Portrait of Aortic valve

Anatomy · Heart & blood vessels

Aortic valve

Three semilunar cusps

Heart · outflow valve of the left ventricle

The valve at the exit of the left ventricle, preventing blood from flowing back from the aorta. It has three half-moon (semilunar) cusps, named right, left and posterior (non-coronary). Behind each cusp the aortic wall bulges into a sinus, and the two coronary arteries arise from the right and left sinuses.

How to spot them

  • ▸Three pocket-shaped semilunar cusps, with a small thickened nodule at the middle of each free edge
  • ▸Behind each cusp, a bulge in the aortic wall: the aortic sinus (of Valsalva)
  • ▸Right and left coronary arteries arise from the right and left sinuses; the posterior one has none
  • ▸Has no chordae tendineae or papillary muscles; the cusps close by back-pressure of blood

What to know

A three-cusped valve of half-moon shape at the exit of the left ventricle

Aortic valve — the cusps are right, left and posterior (non-coronary).

Coronary arteries arise from the sinuses behind two of its cusps

Aortic valve — right and left aortic sinuses; the third is the non-coronary sinus.

The bulges behind its cusps are named after an Italian anatomist of the 17th–18th centuries, Antonio Maria Valsalva

Aortic valve — the sinuses of Valsalva.

Its closure makes the second heart sound, and the loudest part is heard at the second right intercostal space

Aortic valve — A2; aortic area.

A congenital form with only two cusps affects roughly 1–2% of people and predisposes to early calcification

Aortic valve — bicuspid aortic valve.

Narrowing in the elderly gives an ejection systolic murmur radiating to the carotids, and can be treated by a catheter-delivered replacement (TAVI)

Aortic valve — aortic stenosis.

A tiny nodule at the centre of each cusp's free edge, the nodule of Arantius, ensures a tight seal

Aortic valve — the nodules of Arantius.

Key ideas

  • Semilunar valves close passively when pressure in the aorta exceeds that in the ventricle, catching blood in the cusps' pockets; this backflow also fills the coronary arteries in diastole.
  • Three cusps meet at commissures; closure is by their edges (the lunulae) coapting.

Quick-fire facts

  • •Cusps: right, left and posterior (non-coronary) semilunar cusps.
  • •Coronary arteries arise from the right and left aortic sinuses of Valsalva.
  • •Normal valve area is about 3–4 cm2; severe stenosis is usually below about 1 cm2.
  • •Bicuspid aortic valve is the commonest congenital heart abnormality in adults, in roughly 1–2% of the population, more often in men.
  • •Aortic stenosis in older people is commonly due to calcific degeneration; TAVI (transcatheter aortic valve implantation) offers replacement without open surgery.
  • •Its closure produces the A2 component of the second heart sound.
  • •The anterior mitral cusp lies immediately behind the aortic valve's left and posterior cusps.
  • •The Ross procedure replaces a diseased aortic valve with the patient's own pulmonary valve.

Drill it — 7 cards

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Sources