Revision 47 for 'Aortic valve stenosis'

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Aortic valve stenosis

Aortic valve stenosis (also known as aortic stenosis) is the most common type of valvular heart disease that requires valve replacement. It can be classified according to the anatomical location: supravalvular, valvular and subvalvular 1

Epidemiology

There are several causes of aortic valve disease that include bicuspid aortic valve, degenerative aortic valve disease and rheumatic heart disease. 

Bicuspid aortic valve is the most common congenital cardiac anomaly with a prevalence of 4.6 in 1,000 live births 5.

Incidence of degenerative aortic valve disease is increasing. Risk factors are closely associated with atherosclerosis including diabetes, smoking, hypertension and dyslipidemia. 

Rheumatic heart disease is the late sequale of rheumatic fever, a rare multisystem disease caused by an immunological response to Group A streptococcus infection. This is in the decline in developed countries and is more common in the Aboriginal and Maori populations and other disadvantaged groups world-wide. 

Clinical presentation

  • asymptomatic
  • triad 
    • angina pectoris
    • dyspnea 
    • syncope
  • crescendo-decrescendo mid-systolic murmur
  • increased risk of sudden cardiac death

Pathology

Classification
  • supravalvular 
    • congenital: isolated or in association with William syndrome
    • acquired: post surgical or sequelae of aortitis
  • valvular
    • congenital - (congenital aortic valve stenosis) most frequent cause of aortic valve stenosis age in patients between 15 and 65 of age and often arises in associated with anomalous valves
      • bicuspid aortic valve: deformed aortic valves with two functional leaflets or cusps which are often unequal in size (60%); a calcified bicuspid aortic valve is considered the most frequent form of adult aortic valve stenosis
      • tricuspid aortic valve: aortic valves with three functional leaflets or cusps which are often unequal in size (30%)
      • unicommissural/unicuspid aortic valve: dome-like aortic valve with stenosis at very young age (10%) 
      • quadricuspid aortic valve (rare)
  • subvalvular
    • congenital 
      • subaortic membrane
      • idiopathic hypertrophic subaortic stenosis associated with hypertrophic cardiomyopathy

Radiographic features

Plain film - chest radiograph

Variable appearance depending on stage and severity of the disease. 

In early disease, the chest radiograph can be entirely normal or it may show dilatation of the ascending aorta with a normal heart size. Differentiation with hypertension can usually be made as in hypertension the entire descending aorta is enlarged. 

Late in the disease, the chest radiograph is characterized by cardiac enlargement and features of heart failure - pulmonary venous congestion, pulmonary interstitial/alveolar edema. At this stage it is not possible to differentiate aortic stenosis from other causes of heart  failure. 

CT/cardiac CT

A high aortic valve calcification score determined with cardiac CT may indicate severe aortic stenosis, particularly in patients with non-rheumatic acquired calcific aortic valve stenosis 3.

MRI
  • structural assessment on spin echo MR sequence 1
    • biscupsid or unicupsid (rare) aortic valve
    • post stenotic dilatation of ascending aorta
    • symmetrical left ventricular (LV) hypertrophy wall thickness (>/= 12 mm)
    • increased LV mass
  • dynamic assessment on cine GRE or b-SSEP 1
    • thickened valve leaflets with reduce excursion during systole
    • size and extent of high-velocity jet into the ascending aorta
    • hyperdynamic LV contraction in compensated state

Treatment and prognosis

Decision on treatment for aortic stenosis is based on symptoms, left ventricular (LV) dysfunction and coronary artery disease. In symptomatic patient or asymptomatic patients with LV dysfunction, surgical aortic valve replacement is the mainstay of treatment. 

Alternatively percutaneous balloon vavuloplasty is indicated in non-calcific aortic valves in young adults or patient with aortic stenosis who are of high anesthetic risk for open heart surgery.

Transcatheter aortic valve implantation (TAVI) is a less-invasive surgical technique for valve replacement in patients with aortic valve stenosis.

Differential diagnosis

The differential of a dilated ascending aorta includes:

See dilatation of the ascending aorta and aortitis for a more complete discussion. 

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