Bicuspid aortic stenosis
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Associate Editors-In-Chief: Claudia P. Hochberg, M.D. [2]; Abdul-Rahman Arabi, M.D. [3]; Keri Shafer, M.D. [4]
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Epidemiology
The most common congenital abnormality of the heart is the bicuspid aortic valve. Approximately 1-2% of the population have bicuspid aortic valves, and the majority will cause no problems. It can be manifested as a murmur. In this condition, instead of three cusps, the aortic valve has two cusps which results from the fusing of one of the commissures.
This condition is often undiagnosed until later in life when the person develops symptomatic aortic stenosis. Aortic stenosis occurs in this condition usually in patients in their 40s or 50s, an average of 10 years earlier than can occur in people with congenitally normal aortic valves. 30% of cases are diagnosed in adolescence.
The congenital bicuspid aortic valve may become calcified, which may lead to half the cases of surgically important pure aortic stenosis in adults, with varying degrees of severity of aortic stenosis and aortic regurgitation.
Congenital aortic stenosis accounts for 5% of congenital heart defects, is the most common congenital anomaly and is more common in men than women (3:1 to 5:1).
Anatomy
In 1513, Leonardo da Vinci was the first artist who first sketched the bicuspid aortic valve as cuspal inquelity.
The Bicuspid Aortic Valve has two cusps: one larger than the other. It is considered unobstructive if the edges of the cusps are free. If the edges are fused or no free the aortic valve is considered obstructive developing a dome during systole.
There are five varieties of congenitally abnormal aortic valves based on the number and types of cusps and commisures:
- Unicuspid:
- Acommissural
- Unicommissural
- Bicuspid
- Tricuspid:
- Miniature (small aortic ring)
- Dysplastic
- Cuspal inequality
- Quadricuspid
- Six-cuspid
Pathophysiology and Natural History
A congenital bicuspid aortic valve may be associated with the development of either progressive clacific stenosis or regurgitation. The defect is the leading cause of acquired calcified aortic stenosis (see above section on acquired aortic stenosis).
Clinical Features
Signs and Symptoms
Symptoms may not develop until adolescence (in later adulthood with acquired AS) and include DOE, exertional dizziness or syncope, exertional angina and heart failure. Occassionally patients with aortic stenosis may present with fever and bacteremia as these patients are highly susceptible to bacterial endocarditis. Lastly, patients with congenital bicuspid aortic valves may present with aortic aneurysms or dissections as aortic root enlargement from cystic medial changes occur commonly in these patients.
Physical Examination
- There is a systolic murmur from birth (occurs later in life in acquired AS),
- Unlike acquired AS, the contour of the carotid pulse is not a good predictor of severity in congenital AS because it is so variable.
- Because the valve is not calcified early on in the case of a fused valve, a click is present unlike acquired AS.
- Patients often have an S4.
Imaging Studies
- 2 D ECHO plays an important role in the diagnosis of bicuspid AS.
- Short axis is useful, doming of valve can be seen on the parasternal long axis.
- Important to diagnose because of risk of endocarditis and calcification with progressive valvular stenosis.
- Only 25% of patients with congenital AS have AI compared with 75% of cases with acquired AS.
- In 75% of those with acquired AS, there is associated mitral valve disease. This association is rare in congenital AS.
- Congenital AS may occur with one or three cusps, but two cusps is the most common.
- Echocardiographic features that are associated with a poor prognosis in asymptomatic patients and progression to a symptomatic state include moderate to severe calcification and a peak aortic velocity > 4.0 M/s. [1]
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- Bicuspid Aortic Valve by Transesophageal Echo 1
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- Bicuspid Aortic Valve by Transesophageal Echo 2
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- Bicuspid Aortic Valve by Transesophageal Echo 3
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- Bicuspid Aortic Valve by Transesophageal Echo 4
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- Bicuspid Aortic Valve by Transesophageal Echo 5
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- Bicuspid Aortic Valve by Transesophageal Echo 6
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- Bicuspid Aortic Valve by Transesophageal Echo 7
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References
- ↑ Cohn LH, Edmunds LH Jr. Cardiac Surgery in the Adult. McGraw-Hill, 2003.