Bicuspid Aortic Valve

The most common congenital heart anomaly, present in about 1 to 2% of people, with male to female ratio of about 2 to 3:1.

• Two functional cusps instead of three, most often from fusion of the right and left cusps (about 70 to 80%). Familial and genetic (NOTCH1 variants); about 10% of first degree relatives are affected.
• Associated aortopathy (dilatation of the root and ascending aorta) and coarctation in a minority.
• About one third need valve intervention in life. Complications: stenosis (most common), regurgitation, endocarditis, aortic dilatation and dissection (raised relative risk, low absolute risk).

• Often asymptomatic into adulthood; found by murmur or incidental imaging.
• Ejection click, ejection systolic murmur (stenosis), early diastolic murmur (regurgitation).
• Symptoms: exertional dyspnoea, angina, syncope (stenosis, usually in the 40s to 60s); dyspnoea and palpitations (regurgitation); fever and embolic signs (endocarditis); sudden chest or back pain (dissection).
• Differential diagnosis: unicuspid valve, degenerative or rheumatic aortic stenosis, subvalvular or supravalvular obstruction, Marfan syndrome, Turner syndrome.
• Complications: stenosis (most common), regurgitation, endocarditis, aortic dilatation and dissection (raised relative risk, low absolute risk).

• Echocardiography: systolic doming, eccentric closure, raphe, "fish mouth" opening in short axis. Measure the annulus, sinuses, sinotubular junction and ascending aorta at the same levels each time.
• Severe aortic stenosis: peak velocity 4 m/s or more, mean gradient 40 mmHg or more, valve area 1.0 cm2 or less (indexed 0.6 cm2/m2 or less).
• Severe aortic regurgitation: vena contracta greater than 0.6 cm, regurgitant volume 60 mL or more, regurgitant fraction 50% or more, effective regurgitant orifice area 0.3 cm2 or more.
• CT or MR angiography once at baseline for the full aorta (including the arch) when echocardiography is incomplete, and to exclude coarctation.
• Echocardiography of first degree relatives. ECG, chest X-ray.

• No drug prevents valve progression. Control hypertension (amlodipine 5 to 10 mg daily, ramipril 2.5 to 10 mg daily, or losartan 50 to 100 mg daily). Beta blockers (bisoprolol 2.5 to 10 mg daily) are used for hypertension; evidence that they slow aortic growth is limited.
• Avoid fluoroquinolones and heavy isometric lifting.
• Surveillance of the valve: echocardiography every 3 to 5 years (mild), every 1 to 2 years (moderate), every 6 to 12 months (severe). Aorta: imaging every 2 to 3 years if less than 40 mm, yearly at 40 to 44 mm, every 6 to 12 months at 45 mm or more or if growth is rapid.
• Valve intervention indications:
  • Severe aortic stenosis with symptoms, ejection fraction less than 50%, or when other cardiac surgery is needed.
  • Asymptomatic very severe stenosis (peak velocity 5 m/s or more) or rapid progression (rise of 0.3 m/s per year or more) at low surgical risk.
  • Severe regurgitation with symptoms, ejection fraction 50% or less, left ventricular end systolic diameter greater than 50 mm, or end diastolic diameter greater than 65 mm.
• Aortic replacement thresholds: ascending aorta 55 mm or more in all; 50 mm or more with family history of dissection, growth of 3 mm per year or more, coarctation or hypertension; 45 mm or more when valve surgery is planned.
• Choice of valve: mechanical valve favoured under age 50, bioprosthetic over age 65, shared decision between. Transcatheter replacement for older or high risk patients with suitable anatomy. Valve repair or the Ross procedure in selected young patients. Balloon valvuloplasty in children and young adults with non-calcified stenosis and gradient greater than 50 mmHg.
• Anticoagulation: mechanical aortic valve, warfarin target INR 2.5 (range 2.0 to 3.0) without risk factors, 3.0 (range 2.5 to 3.5) with atrial fibrillation, previous thromboembolism, ejection fraction less than 35% or a hypercoagulable state. Direct oral anticoagulants must not be used with mechanical valves. Bioprosthetic valve: warfarin to INR 2.5 for 3 months, or aspirin 75 to 100 mg daily.
• Endocarditis prophylaxis before dental procedures only after valve replacement or previous endocarditis: amoxicillin 2 g orally (50 mg/kg in children) 30 to 60 minutes before; azithromycin or clarithromycin 500 mg (15 mg/kg in children) if allergic to penicillin (clindamycin is no longer recommended).
• Special groups: pregnancy (tolerated with mild to moderate disease and aorta less than 45 mm; counsel against pregnancy and repair beforehand with severe symptomatic stenosis or aorta 45 mm or more; beta blocker and balloon valvuloplasty for refractory failure in pregnancy); children (critical stenosis needs early valvuloplasty); elderly (transcatheter route preferred in high surgical risk).
• Red flags: chest or back pain (dissection), fever with new murmur (endocarditis), syncope, pulmonary oedema.
• Follow up: lifelong, with echocardiography every 3 to 5 years (mild valve disease), every 1 to 2 years (moderate) or every 6 to 12 months (severe), aortic imaging every 2 to 3 years if the aorta is less than 40 mm, yearly at 40 to 44 mm and every 6 to 12 months at 45 mm or more, and first degree relative screening.