Aortic Regurgitation, Acute

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Usually due to aortic dissection, endocarditis, or trauma

• Sudden, severe dyspnea, orthopnea, and weakness

• Signs of pulmonary edema

• Soft S₁ and S₃ and short decrescendo diastolic murmur at the base

• Characteristic Doppler echocardiographic findings:

  • – Confirm aortic regurgitation (color jet)

  • – Estimate its severity (short pressure half-time)

  • – Estimate left ventricular pressure (premature closure of mitral valve, diastolic mitral regurgitation)

GENERAL CONSIDERATIONS

• Sudden, severe aortic regurgitation does not allow time for the left ventricle to adapt

• The acute volume load on a relatively noncompliant left ventricle leads to immediate and marked increases in filling pressures, which:

  • – Are transmitted to the lungs

  • – Result in acute pulmonary edema

• Because left ventricular diastolic volume is initially normal, total stroke volume does not increase and forward stoke volume decreases, resulting in:

  • – Sympathetic stimulation

  • – Peripheral vasoconstriction

  • – Worsening of aortic regurgitation

• Acute aortic regurgitation is usually due to:

  • – Leaflet abnormalities that cause sudden disruption or prolapse such as infective endocarditis

  • – Other vasculitides or trauma

  • – Occasionally, sudden root dilatation, as occurs with aortic dissection

  • – Ruptured sinus of Valsalva aneurysm—most common congenital cause

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Sudden, severe dyspnea, orthopnea, and weakness

• Rapid progression to hemodynamic collapse

PHYSICAL EXAM FINDINGS

• Normal pulse pressure

• Possible hypotension

• Pulmonary rales

• Normal left ventricular impulse

• Auscultation findings:

  • – Soft S₁ due to premature closure of the mitral valve

  • – S₃

  • – Short high-pitched aortic diastolic murmur

• Absent pulses if due to aortic dissection

DIFFERENTIAL DIAGNOSIS

• Other causes of acute pulmonary edema

• Aorto-left ventricular fistula due to endocarditis

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• CBC: Elevated white blood cell count and positive blood cultures if due to endocarditis

• Specific tests for various vasculitides may be helpful, such as antinuclear antibodies

• Brain natriuretic peptide levels elevated in proportion to severity and may aid in decision for surgery

ELECTROCARDIOGRAPHY

• Sinus tachycardia

• Atrioventricular nodal disease if cause is infective endocarditis

IMAGING STUDIES

• Chest x-rays to detect:

  • – Wide mediastinum if aortic dissection

  • – Pulmonary edema

  • – Broken ribs if due to trauma

• Echocardiography to detect:

  • – Structural abnormalities of the valve or aortic root

  • – Early closure of the mitral valve

• Transesophageal echo better if endocarditis or aortic dissection considered

• Doppler echocardiography—color flow identification of the leak:

  • – If severe, a truncated continuous-wave Doppler signal of aortic regurgitation is found, because pressure between the aorta and the left ventricle equilibrates rapidly; this results in a short pressure half-time by continuous-wave Doppler of the jet

  • – There may be diastolic ...