Causes of Acute Aortic Regurgitation
The primary causes of acute aortic regurgitation are infective endocarditis, aortic dissection, trauma, and iatrogenic complications from interventional procedures, with infective endocarditis and aortic dissection being the most common and life-threatening etiologies. 1
Primary Etiologies
Valve-Related Causes
- Infective endocarditis: Leading cause of acute AR, causing valve destruction, perforation, or flail leaflets 1
- Trauma: Direct injury to aortic valve from blunt chest trauma 1
- Iatrogenic causes:
Aorta-Related Causes
- Aortic dissection: Major cause of acute AR due to disruption of valve support 1
- Rupture of sinus of Valsalva aneurysm: Causing acute AR with hemodynamic compromise 1
Less Common Causes
- Prosthetic valve dysfunction: Paravalvular leak, structural valve deterioration, or thrombosis
- Connective tissue disorders: Acute decompensation in Marfan syndrome or other collagen vascular diseases 1
- Inflammatory conditions: Ankylosing spondylitis, rheumatoid arthritis, giant cell arteritis 1
- Trauma to ascending aorta: Leading to aortic root disruption 1
Pathophysiological Consequences
Acute AR creates dramatic hemodynamic changes because the left ventricle has not had time to accommodate the sudden volume overload:
- Abrupt increase in LV end-diastolic pressure and volume
- Rapid elevation of left atrial pressure leading to pulmonary edema
- Decreased forward cardiac output resulting in hypotension
- Myocardial ischemia due to reduced coronary perfusion pressure 1, 2
The severity is particularly pronounced in patients with pre-existing pressure overload hypertrophy (e.g., systemic hypertension, aortic stenosis) due to reduced LV compliance 1.
Diagnostic Challenges
Acute AR can be difficult to diagnose clinically because:
- Classic peripheral signs of chronic AR (wide pulse pressure, bounding pulses) may be absent
- Diastolic murmur may be soft or short due to rapid pressure equilibration
- Normal heart size on chest X-ray (no time for cardiac remodeling)
- Rapid progression to heart failure and cardiogenic shock 1, 2
Clinical Implications
Early recognition and prompt intervention are critical for survival in acute severe AR. Mortality approaches 20% even with appropriate treatment, and significantly higher without intervention 1.
Transesophageal echocardiography (TEE) is the gold standard for diagnosis with 98-100% sensitivity and 95-100% specificity, particularly important in suspected aortic dissection 1, 2.
Important pitfall: The severity of acute AR is frequently underestimated due to subtle physical findings and normal heart size on imaging. High clinical suspicion and early echocardiographic assessment are essential for timely diagnosis 2.