Aortic regurgitation

aortic-regurgitation

Aortic insufficiency (AI), also known as aortic regurgitation (AR), is the leaking of the aortic valve  of the heart  that causes blood to flow in the reverse direction during ventricular diastole, from the  aorta into the left ventricle.  Aortic insufficiency can be due to abnormalities of either the aortic valve or the aortic root (the beginning of the aorta )

Causes:

[A] Congenital:

  • Bicuspid valve or
  • Disproportionate cusps.

[B] Acquired:

  • Rheumatic heart disease.
  • Infective endocarditis.
  • Trauma.
  • Aortic dilatation (Aneurysm, dissection, syphilis)

Physiology: In individuals with a normally functioning aortic valve, the valve is only open when the pressure in the left ventricle is higher than the pressure in the aorta. This allows the blood to be ejected from the left ventricle into the aorta during ventricular systole.  The amount of blood that is ejected  by the heart is known as the stroke volume.  Under normal conditions, 50–70% of the blood in a filled left ventricle is ejected into the aorta to be used by the body (called the ‘ejection fraction’). After ventricular systole, the pressure in the left ventricle decreases as it relaxes and begins to fill up with blood from the left atrium.This relaxation of the left ventricle (early ventricular diastole ) causes a fall in its pressure. When the pressure in the left ventricle falls below the pressure in the aorta, the aortic valve will close, preventing blood in the aorta from going back into the left ventricle.

 

Clinical features:

Symptoms:

  1. Mild to moderate AR:
  • Often asymptomatic.
  • Awareness of heart beat (palpitations)
  1. Severe AR:
  • Breathlessness.
  • Angina.

Signs:

  1. Pulse:
  • Large volume or ‘Collapsing pulse’.
  • Bounding peripheral pulses.
  • Capillary pulsation in nail beds-Quincke’s sign.
  • Femoral bruit (Pistol shot)-Duroziez’s sign.
  • Head nodding with pulse-de Musset’s sign.
  1. Blood pressure:
  • High systolic pressure.
  • Low diastolic pressure.
  • High pulse pressure.
  1. Precordium (cardiac findings):

(a)    Inspection:

  • Apex-beat visible.
  • Shifted downwards and outwards (if LVF).

(b)   Palpation:

  • Thrusting (heaving) apex beat.
  • Early diastolic thrill.

(c)    Auscultation:

  • First heart sound-normal.
  • Secondary heart sound-soft.
  • Early diastolic murmur (the murmur of AR)
  • Systolic murmur (↑ed stroke volume over aortic area)
  • Fourth heart sound.
  1. Other signs:
  • Displaced, heaving apex beat (volume overload).
  • Presystolic impulse.
  • Fourth heart sound.
  • Pulmonary venous congestion (Crepitations)

Investigations:

  1. ECG: Initially normal, later LVH and T wave inversion.
  2. Chest X-ray:
  • Cardiac dilatation, may be aortic dilatation
  • Features of left heart failure (LHF).
  1. Echocardiography:
  • Dilated left ventricle.
  • Hyperdynamic left ventricle.
  • Fluttering anterior mitral leaflet.
  • Doppler detects reflux.
  1. Cardiac catheterization:
  • Dilated left ventricle.
  • Aortic regurgitation.
  • Dilated aortic root.

Management:

Medical treatment:

  1. a) Diuretics (if symptoms are mild or patient is inoperable)
  2. b) Antibiotics prophylaxis against endocarditis.
  3. c) Vasodilators (e.g. ACE-inhibitors): to prevent progressive left ventricular dilatation.
  4. d) Treatment of underlying condition, e.g. syphilis.

Surgical treatment: Aortic valve replacement under cardiopulmonary bypass. Surgery is also indicated in asymptomatic patients if there is progressive radiological cardiolomegaly or echo evidence of deteriorating left ventricle function. When aortic root dilatation is the cause of aortic regurgitation (e.g. Marfan’s syndrome) aortic regurgitation (e.g. Marfan’s syndrome) aortic root replacement may be necessary.

Reference:

  1. Davidson’s Principles and Practice of Medicine, 21st edition.
  2. Wikipedia the free encyclopedia.

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