Aortic regurgitation general approach to aortic insufficiency

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]

Overview

Aortic insufficiency is a valvular disease characterized by the inability of the aortic valve to close tightly leading to a backward flow of blood from the aorta into the left ventricle during diastole.

Classification

Aortic insufficiency can be acute or chronic.

Pathophysiology

During acute aortic regurgitation, there is a sudden large regurgitant volume of blood imposed on the unprepared left ventricle. Because of the acute nature of the onset of the regurgitation, there will be no ventricular dilatation. As the blood flow through the aorta is reversed, the effective left ventricle stroke volume is reduced. As a result, the left ventricular end diastolic pressures will increase and consequently pulmonary edema may occur.

Causes

Aortic insufficiency can be caused by defects in the intrinsic aortic valve or the ascending aorta (root).

• Defects in the Intrinsic Aortic Valve:
  • Degenerative / calcific aortic valve
  • Endocarditis
  • Bicuspid aortic valve
  • Rheumatic fever
  • Valvulitis
  • Anorectic drugs

• Defecst in the Ascending Aorta (Root):
  • Degenerative
  • Type A aortic dissection
  • Marfan syndrome
  • Giant cell arteries
  • Inflammatory:
    • Reiter's syndrome
    • Behcet's disease
    • Ankylosing spondylitis
    • Relapsing polychondritis
    • Psoriatic arthritis

Differentiating Aortic insufficiency from Mitral regurgitation

Natural History

There are two main parameters that reflect the overall outcome in patients with aortic insufficiency:

• Ejection fraction: the lower the ejection fraction is, the poorer the outcome is.
• End systolic diameter

Left ventricular dysfunction develops in patients with aortic insufficiency after decades of the onset of the symptoms. This lag period is longer than that of mitral regurgitation.

Diagnosis

Symptoms

Acute aortic insufficiency may present with the following symptoms:

• Sudden onset of severe breathlessness (dyspnea)
• Chest pain( chest pain occurs when aortic dissection is the cause of the insufficiency).

Chronic aortic insufficiency causes:

• Exertional dyspnea
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Palpitations

Patients having bicuspid aortic valve should be evaluated for coarctation of aorta if hypertension is present and for dissection of aorta if chest pain is present. Therefore the entire aorta should be scanned either by an magnetic resonance angiogram (MRA) or computed tomography (CT).

Physical Examination

• Bounding pulses may be present
• Head nodding (de Musset's sign) - rhythmic nodding or bobbing of the head in synchrony with the beating of the heart.
• Capillary pulsations (Quincke's sign) - pulsation of arteriolar and venous plexuses of the nail bed causing alternate blanching and flushing.
• Corrigan's pulse - rapid carotid upstroke, rapid collapse
• Duroziez's sign - 'pistol' shot sounds (audible diastolic murmur heard over the femoral artery.
• Early diastolic murmur best heard in the right second intercostal space. The murmur may be soft in acute AR.
• S₃ and S₄ may be heard.

Imaging

Echocardiography is used to assess the following parameters:

• End-diastolic diameter
• End systolic diameter
• Ejection fraction

Echocardiography can also be used to assess the ascending aorta (root) and/or valve causes of insufficiency.

Echocardiographic findings correlated with severe AR include:

• AR color jet dimension/left ventricular outflow tract diameter >60%
• Flow reversal in proximal descending thoracic aorta
• Regurgitant volume >60 ml
• Regurgitant fraction >55%

If the color flow on echocardiography is solely taken into consideration during the evaluation of aortic regurgitation, echocardiographic findings might underestimate or overestimate the severity of the regurgitation. Thus, it is recommended to use cardiac catheterization as an imaging modality. When discrepancy exists between the findings of echocardiography and that of the cardiac catherization, it is recommended to do a left ventriculogram .

• Treadmill testing in aortic regurgitation is used to objectively assess the patient's exercise capacity.
• Magnetic resonance angiogram (MRA) and CT are used to scan the entire aorta when bicuspid aortic valve is present.

Treatment

Acute severe Aortic insufficiency

• Urgent surgical intervention is indicated in the cases of type A aortic dissection and acute prosthetic AR.
• Nitroprusside and ionotropes can be used to maintain blood pressure.
• Treatment options that are contraindicated include:
  • Intra aortic balloon pump
  • Pressors
  • Beta blockers

Chronic Aotic insufficiency

• Vasodilator therapy is indicated for the treatment of severe chronic aortic insufficiency in:
  • Patients with symptoms and/or left ventricular ejection fraction ≤50% and who are not candidates for aortic valve replacement.
  • Asymptomatic patients with AR and hypertension.
• Vasodilator therapy is not indicated for other patients with AR.

Indications for Surgery

Indications for surgery in aortic insufficiency include:

• Very severe insufficiency
• Any symptoms
• Ejection fraction <50%
• End systolic dimension >50 mm