Aortic Regurgitation

Aortic regurgitation (AR) is diastolic leakage of blood from the aorta into the left ventricle.

Causes: aortic root dilatation (hypertension, Marfan syndrome, annuloaortic ectasia, aortitis, syphilis, ankylosing spondylitis), valve disease (bicuspid, rheumatic, endocarditis, degeneration), dissection, trauma, drugs (fenfluramine).

Acute AR (endocarditis, dissection, trauma) causes sudden volume overload without compensation: pulmonary oedema, shock.

Chronic AR: eccentric hypertrophy, left ventricular dilatation, long asymptomatic phase; progression to dysfunction at about 4 to 6% a year once symptoms or dilatation appear.

Severity (echo): vena contracta over 6 mm, regurgitant volume 60 mL or more, regurgitant fraction 50% or more, effective regurgitant orifice 0.3 cm2 or more, pressure half time under 200 ms, holodiastolic flow reversal in descending aorta.

• Chronic: asymptomatic for years, then exertional dyspnoea, fatigue, palpitations, angina.
• Wide pulse pressure, collapsing (water hammer) pulse, early diastolic decrescendo murmur at left sternal edge best heard sitting forward at end expiration, Austin Flint murmur, displaced hyperdynamic apex.
• Peripheral signs: de Musset head nodding, Quincke pulsation, Duroziez sign, Traube sound.
• Acute: tachycardia, pulmonary oedema, soft short diastolic murmur, quiet S1 (premature mitral closure), minimal pulse pressure change.

• Echocardiography: valve morphology, cause, severity, left ventricular size (end systolic diameter, end diastolic diameter) and ejection fraction, aortic root dimensions.
• Cardiac MRI for quantitation when echo is inconclusive; CT angiography for aorta.
• ECG, chest radiograph, BNP; exercise testing in asymptomatic patients.
• Transoesophageal echo for acute AR, endocarditis, dissection.
• Serial echo every 6 to 12 months (severe or dilating), every 1 to 2 years (moderate).

Chronic AR

• Vasodilators (amlodipine 5 to 10 mg, nifedipine ER 30 to 90 mg, ACE inhibitor) for hypertension or symptomatic patients unfit for surgery; not proven to delay surgery in normotensive asymptomatic patients.
• Treat hypertension (systolic below 130 mmHg), aortic disease with beta blocker or ARB (Marfan).
• Surgery indications: symptoms; asymptomatic with ejection fraction 55% or less, end systolic diameter over 50 mm (25 mm/m2), end diastolic diameter over 65 mm; concomitant cardiac surgery; aortic root over 5.5 cm (4.5 to 5.0 in bicuspid or Marfan).
• Options: valve repair (young patients, bicuspid), aortic valve replacement (mechanical with warfarin, bioprosthetic), Ross procedure, valve sparing root replacement; TAVI for high risk patients with suitable anatomy.

Acute AR

• Emergency surgery. Temporise with diuretics, sodium nitroprusside 0.25 to 0.5 micrograms/kg/min, inotropes (dobutamine). Avoid beta blockers and intra aortic balloon pump.
• Endocarditis: antibiotics per cultures; early surgery for heart failure.

General

Endocarditis prophylaxis for prosthetic valves and prior endocarditis, dental care, treat syphilis (penicillin), screen first degree relatives of bicuspid disease, avoid isometric exercise in dilated root.