Bicuspid Aortic valve

Images by Genevieve Carbonatto

A young 23 year old man presents to the Emergency Department with chest pain. A point of care ECHO is performed. An incidental finding of a bicuspid aortic valve is found.

Parasternal long axis of left ventricle (PLAX) showing that the aortic valve closure is eccentric. It  closes more towards the right coronary sinus than in the centre of the aortic root.

Parasternal long axis of the left ventricle with colour flow across the aortic valve demonstrating a mild, very eccentric jet of aortic regurgitation, (AR) into the LV during diastole.

Parasternal short axis at the level of the aortic valve.  Notice that the diagnosis of bicuspid aortic valve is made during systole when the valve is open. It doesn’t open like a triangle but like an aussie rules football.

Parasternal short axis at the level of the aortic valve with colour across the valve again showing the very eccentric jet of mild AR.

Discussion

What is a bicuspid aortic valve?

An aortic bicuspid valve is an aortic valve which has 2 leaflets instead of 3. 2 of the usual 3 leaflets are congenitally fused. BAV is associated with three types of configurations

  1. “Real” bicuspid valves with two symmetric leaflets
  2. A tricuspid architecture with a fusion of two leaflets
  3. A tricuspid architecture with a fusion of three leaflets

Diagnosis

BAV is best diagnosed by transthoracic ECHO or  transoesophageal ECHO. Cardiac  MRI and CT are used  to augment the diagnostic process. MRI especially  enables views of the valve to be obtained without interference from calcification. It also allows for excellent assessment of the aorta. (4)

What are the 2D ECHO features suggestive of BAV?

PLAX :

  • The aortic valve may have an eccentric closure. This may be associated with an eccentric aortic regurgitant jet
  • The aortic valve may have a ” domed appearance” in the PLAX
  • There may be associated aortic root dilatation

The following is another young patient who was identified in the Emergency Department with a bicuspid valve which was subsequently followed up in the cardiology department and which shows a “domed” appearance of the aortic valve.

PSAX :

  • The normal triangular shape is lost, becoming more “fish mouth” or AFL ball, closer to a mitral valve opening. This is especially visible in systole when the AV is opening as in diastole, the raphe can appear similar to a commisure of the third cusp

Normal tricuspid valve opening – triangular shape

Bicuspid valve opening which is more fishmouth or AFL ball shape

What are the complications of BAV?

A bicuspid aortic valve (BAV) is the most common cardiac congenital abnormality affecting 1% of the population

Complications associated with bicuspid valves include

  • Aortic stenosis : This is the most common complication and affects most people in the middle age
  • Aortic regurgitation: May present with or without AS (aortic stenosis). Causes of regurgitation may include cusp prolapse, endocarditis, dilated aortic root and myxoid degeneration of the valve
  • AV calcification
  • Endocarditis: more common in patient with BAV and worse outcome

BAV  has also been associated with

  • Dilated aortic root which may lead to aortic aneurysm (AV aortopathy)
  • Aortic dissection : Aortic root dilatation is an important predictor of aortic dissection, which is related to underlying aortopathy, cystic medial degeneration, and hemodynamic factors.
  • Coarctation of the aorta in 20 % of people with BAV
  • Less commonly it is associated with ventricular septal defects , ebstein’s anomaly, hypoplastic left heart syndrome, abnormal coronary anatomy, patent ductus arteriosus, atrial septal defects and bicuspid pulmonary valve

What are the indications for elective surgery?

The ACC/AHA guidelines and ESC guidelines recommend the following for elective aortic valve surgery

After bicuspid aortic valve replacement, the patient remains at risk for late ascending aortic complications including aneurysm formation and dissection. Surveillance of the aortic valve late after bicuspid aortic valve replacement is necessary.

Teaching point: This patient presented with an incidental bicuspid aortic valve. Even though this eventually was unrelated to his presenting symptoms, it was identified and enabled cardiology follow up. 

References

  1.  Up to date : Bicuspid valve
  2. ESC : Bicuspid aortic valve Dr Adel Chabana Vol 13 No 2-26 September 2014
  3. ECHO ROUNDS Section Editor: E. Kenneth Kerut, M.D. How Not to Miss a Bicuspid Aortic Valve in the Echocardiography Laboratory Salvatore J. Tirrito, M.D.∗ and Edmund Kenneth Kerut, M.D.∗,†
  4. Cardiology Research and PracticeVolume 2012 (2012), Article ID 196037, 7 pageshttp://dx.doi.org/10.1155/2012/196037 Review Article Bicuspid Aortic Valve Disease: A Comprehensive Review

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