Revision 30 for 'Bicuspid aortic valve'All Revisions
Bicuspid aortic valve
A 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 "pure" BAV subtype. However, usually there are three cusps associated with underdevelopment of a commissure and fusion of two adjacent cusps to form a raphe in the more common form of BAV7. Over time, the abnormal stress across the valve leads to calcification, usually in adulthood.
- autosomal dominant polycystic kidney disease
- coarctation of the aorta: ~70% (range 50-85%) of coarctations are thought to associated with bicuspid aortic valves 2
- Turner's syndrome
- left sided lesions eg hypoplastic left heart
- other congenital lesions eg atrial and ventricular septal defects, patent ductus arteriosus
- intracranial aneurysm
The usefulness of plain film 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 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 much higher reported detection rate for bicuspid valves and include 6
- sensitivity : 94 %
- specificity : 100 %
- positive predictive value : 100 %
- nagative predictive value : 97 %
Characteristic “fish-mouth” shape of the open valve in systole is noted on ECG gated cardiac CT 7.
Cardiac MRI has the advantage of demonstrating the dynamic motion of the bicuspid valve when heavily calcified valves make echocardiography difficult to interpret. Further, MRI can provide non-invasive assessment of the ascending aortic diameter and the presence of a coarctation in a single study.
Recognized complications include
- aortic stenosis
- aortic insufficiency
- aortic aneurysm - an aortopathy is present irrespective of the valve function. Aortic dilatation (and dissection) is due to abnormal media. As such, bicuspid aortic valve 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 abnormal media
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 replacement9.