Bicuspid aortic valve

Bicuspid aortic valve (BAV) refers to a spectrum of deformed aortic valves with two functional leaflets or cusps which are often unequal in size.

They are most often congenital while an acquired bicuspid valve occurs when there is fibrous fusion between the right and left cusps of a pre-existing trileaflet aortic valve.

A congenitial biscuspid aortic valve is considered to be one of the most common causes of isolated aortic stenosis 4. It is considered a major cause of aortic valve disease in young adults.

The estimated incidence of a congenital bicuspid valve in the general population is thought to be ~2%. They may be more common in males.

BAV refers to a spectrum of deformed aortic valves with two functional leaflets or cusps which are often unequal in size. Only two cusps, commissures and sinuses are seen in the less common "pure" BAV subtype. The more common form of BAV occurs in a valve with three cusps with underdevelopment of a commissure and fusion of two adjacent cusps to form a raphe 7. Over time, the abnormal stress across the valve leads to calcification, usually in adulthood.

Several classification have been proposed with one of the more common being

  • type I
    • type Ia: raphe between right coronary cusp and left coronary cusp 
    • type Ib: purely bicuspid with fusion between left and right coronary cusps
  • type II
    • type IIa: raphe between right coronary cusp (RCC) and non coronary cusp (NCC)
    • type IIb: purely bicuspid with fusion between non coronary and right coronary cusps
  • type III
    • type IIIa: raphe between left coronary cusp (LCC) and non coronary cusp (NCC)
    • type IIIb: purely bicuspid with fusion between non coronary and left coronary cusps

The usefulness of plain chest radiographs in the detection of a bicuspid valve is considered to be rather poor. Occasionally the presence of a single calcified raphe at the expected site of the bicuspid valve, which is best seen on lateral view as aortic valve is superimposed on spine on frontal radiographs, as well as post stenotic dilatation of the ascending aorta may suggest a biscuspid valve 4.

While echocardiography is the standard diagnostic procedure for the evaluation of patients with valvular disease, differentiation of bicuspid valve from other types of calcific aortic stenosis can sometimes be difficult 4,5.

At the time of initial writing, an echocardiogram for the detection of a bicuspid aortic valve is thought to carry 6:

  • sensitivity: 76%
  • specificity: 60%
  • positive predictive value: 68%
  • negative predictive value: 95%

At the time of writing, CT has a much higher reported detection rate for bicuspid valves and include 6:

  • sensitivity: 94%
  • specificity: 100%
  • positive predictive value: 100%
  • negative predictive value: 97%

Characteristic “fish-mouth” shape of the open valve in systole is noted on ECG-gated cardiac CT 7.

There is often earlier leaflet calcification.

Cardiac MRI has the advantage of demonstrating the dynamic motion of the bicuspid valve when heavily calcified valves make echocardiography difficult to interpret. Furthermore, MRI can provide non-invasive assessment of the ascending aortic diameter and the presence of a coarctation in a single study.

Experimental 4D MRI studies have suggested a "hurricane aorta" like flow pattern 13.

A minority of patients develop aortic regurgitation as a young adult but the majority have progressive valve stenosis, with only about 1% maintaining normal valve function over their lifetime 10.

High blood pressure should be controlled.

Symptomatic children have very little calcification, and are treated by balloon valvuloplasty. Also, insertion of a valve in a child is not advisable, as the child will continue to grow.

In adults, aortic valve replacement is performed, and occurs in a younger age group than in patients with tri-leaftlet valve stenosis. Aortic root replacement is also required in 30% of patients undergoing valve replacement 9.

Recognized complications include:

  • aortic stenosis
    • this is secondary to leaflet calcification which occurs earlier (around age 40) than in patients with tri-leaflet aortic valves
    • turbulent flow across the valve predisposes to leaflet calcification
  • aortic insufficiency
    • in children: incompetence develops secondary to redundant valve leaflets, endocarditis, or following balloon valvuloplasty
    • in adults: dilatation of the ascending aorta can lead to regurgitation
  • ascending aortic aneurysm
    • an aortopathy is present irrespective of the valve function; aortic dilatation (and dissection) is due to abnormal media; as such, BAV can be considered a disease of both the valve and ascending aorta, and this should be a consideration in surgical decision making
  • aortic dissection: secondary to aortopathy and abnormal media
  • infective endocarditis: due to turbulent flow
Anatomy: Thoracic

Anatomy: Thoracic

Share article

Article information

rID: 16604
System: Cardiac
Section: Anatomy
Synonyms or Alternate Spellings:
  • Bicuspid aortic valve (BAV)
  • Congenitial biscuspid aortic valve
  • Bileaflet aortic valve
  • Bi-leaflet aortic valve
  • Bicuspid aortic valves

Support Radiopaedia and see fewer ads

Cases and figures

  • Case 1: with aortic valve stenosis
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Case 3: with Ross procedure
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.