What is aortic regurgitation?

Aortic Regurgitation Definition and Management

Aortic regurgitation (AR) is defined as the backward flow of blood from the aorta into the left ventricle during diastole due to imperfect functioning or incompetence of the aortic valve. 1

Pathophysiology and Classification

Aortic regurgitation results from either:

1. Primary causes - intrinsic disease of the aortic valve leaflets
2. Secondary causes - distortion and dilatation of the aortic root
3. Mixed pathology - combination of both mechanisms 1

The El Khoury functional classification helps understand AR mechanisms:

• Type I: Normal leaflet motion with aortic root dilatation
• Type II: Excessive leaflet motion (prolapse)
• Type III: Restrictive leaflet motion 1, 2

Etiology

Common causes of AR include:

• Congenital abnormalities:

  • Bicuspid aortic valve (most common congenital risk factor) 2
  • Coarctation of the aorta 2

• Acquired conditions:

  • Degenerative valve disease (senile degeneration)
  • Aortic root dilatation/annulo-aortic ectasia 2
  • Connective tissue disorders (Marfan syndrome) 2
  • Infective endocarditis 2
  • Failed bioprosthetic valves 2

Clinical Presentation

The presentation depends on:

1. Severity of regurgitation
2. Acuity of onset 3

• Acute AR: Presents with severe pulmonary edema and hypotension; surgical emergency 4, 5
• Chronic AR: May remain asymptomatic for years due to compensatory mechanisms 3, 5

Diagnostic Evaluation

Echocardiography

Echocardiography is the primary diagnostic modality for AR 1:

• Transthoracic echocardiography (TTE) is recommended as first-line imaging 1
• Transesophageal echocardiography (TOE) is indicated when TTE is non-diagnostic or further refinement is needed 1
• 3D echocardiography provides additional information in complex valve lesions 1

Defining Severe AR

Severe AR is characterized by 1:

• Vena contracta >0.6 cm
• Effective regurgitant orifice area (EROA) ≥0.3 cm²
• Regurgitant volume ≥60 mL/beat
• Holodiastolic flow reversal in the descending aorta
• Doppler jet width ≥65% of LVOT diameter
• Pressure half-time <200 ms
• Regurgitant fraction ≥50% on CMR

Additional Imaging

• Cardiovascular magnetic resonance (CMR): Useful for assessing biventricular volumes, systolic function, aortic size, and regurgitant fraction 1
• Computed tomography (CT): Valuable for aortic root dimensions and to exclude dissection in acute AR 1

Management

Medical Therapy

• In acute severe AR, medical therapy to reduce LV afterload may be used but should not delay urgent surgical intervention 1
• For chronic AR, vasodilators aim to decrease systolic arterial pressure and delay need for surgery in asymptomatic patients with normal LV function 5

Surgical Intervention

Indications for intervention in asymptomatic severe AR include 1:

• LV systolic dysfunction (LVEF ≤50-55%)
• LV end-systolic diameter >50 mm or >25 mm/m²
• LV end-diastolic diameter >60 mm
• Progressive decline in LV function

Prognosis

• Severe AR is associated with significant cardiovascular morbidity and mortality
• Within 10 years of diagnosis of severe AR, 75% of patients die or require aortic valve replacement
• Even asymptomatic severe AR carries a mortality rate of up to 19% within 6.6 years of diagnosis 1, 2

Monitoring

Regular echocardiographic monitoring is essential to detect progression of AR and LV remodeling, with surgical intervention considered before irreversible LV dysfunction develops 2.