Aortic Stenosis

General Considerations 

• Most often as result of degeneration of bicuspid aortic valve
• Less commonly rheumatic heart disease or secondary to degeneration
  of a tricuspid aortic valve in person > 65 

Location

• Supravalvular
• Uncommon
• Associated with William’s Syndrome
• Hypercalcemia
• Elfin facies
• Pulmonary stenoses
• Hypoplasia of aorta
• Stenoses in
• Renal, celiac, superior mesenteric arteries
• Valvular
• Most common
• Either congenital (from a bicuspid aortic valve) or acquired
• Bicuspid aortic valve is the most common congenital cardiac anomaly
• 0.5 –2%
• Subvalvular
• Associated with
• Hypoplastic left heart syndrome
• Idiopathic Hypertrophic Subaortic Stenosis
• Hypertrophic cardiomyopathy
• Subaortic fibrous membrane 

Types

• Congenital aortic stenosis (more common)
• Most frequent congenital heart disease associated with
  intra-uterine growth retardation (IUGR)
• Subvalvular (30%)
• Valvular (70%)
• Degeneration of bicuspid valve
• Supravalvular
• Acquired aortic stenosis
• Rheumatic valvulitis
• Almost invariably associated with mitral valve disease
• Fibrocalcific senile aortic stenosis
• Degenerative 

Clinical Findings

• Asymptomatic for many years
• Classical triad
• Angina
• Syncope
• Shortness of breath (heart failure)
• Systolic ejection murmur
• Carotid pulsus parvus et tardus
• Diminished aortic component of 2nd heart sound
• Sudden death in severe stenosis after exercise
• Diminished flow in coronary arteries causes ventricular dysrhythmias
  and fibrillation
• Decompensation leads to left ventricular dilatation and pulmonary
  venous congestion

Imaging Findings 

• In older children or young adults
• Prominent ascending aorta
• Poststenotic dilatation of ascending aorta
• Due to turbulent flow
• Left ventricular heart configuration
• Normal-sized or enlarged left ventricle
• Concentric hypertrophy of left ventricle produces a relatively small
  left ventricular chamber with thick walls
• Heart size is frequently normal
• In adults >30 years
• Prominent ascending aorta
• Poststenotic dilatation of ascending aorta
• Due to turbulent flow
• Calcification of aortic valve (best seen on RAO)
• In females, usually indicates hemodynamically significant aortic stenosis
• Calcification of the valve usually indicates a gradient across
  valve of > 50mm Hg
• Calcification begins in bicuspid and rheumatic valve in 4th decade
  but not until > 65 in tricuspid
• DDx
• Calcification of aortic annulus in elderly
• Calcified coronary artery ostium (thickened cusp echoes only in diastole)
• Normal to enlarged left ventricle
  

Echocardiographic findings

• Thickened and calcified aortic valve with multiple dense cusp echoes
  throughout cardiac cycle
• Right > non-coronary > left coronary cusp
• Decreased separation of leaflets in systole with reduced opening orifice
• (13-14 mm = mild AS; 8-12 mm = moderate AS; <8 mm = severe AS)
• ± Doming in systole
• Dilated aortic root
• Increased thickness of LV wall (= concentric LV hypertrophy)
• Hyperdynamic contraction of LV (in compensated state)
• Decreased mitral EF slope (reduced LV compliance)
• LA enlargement
• Increased aortic valve gradient (Doppler)
• Decreased aortic valve area (unreliable)

Angiographic findings

• Simultaneous LV and aortic pressures recordings yield valve gradients from left heart
  catheterization
• Angiographic technique uses standard RAO left ventriculogram and an aortogram
  using a 40° LAO projection
• A non-calcified, bicuspid valve reveals thickening and doming of the valve leaflets
  in systole
• A jet of non-opacified blood is visible through stenotic valve
  • Congenitally bicuspid valves still usually have three aortic sinuses with one large
    non-coronary sinus equal in size to the other two
• Calcification begins in the bicuspid and rheumatic valve in the 4th decade
  but not until >65 in tricuspid
• In rheumatic disease, the aortic valve commissures usually fuse whereas they
  do not in the degenerated tricuspid valve

 Differentiating Causes of Aortic Stenosis

Valve areas

Aortic Stenosis. Top: Axial CT scan through heart demonstrates a heavily
calcified aortic valve (white arrow). Bottom: Frontal chest radiograph in
another patient with aortic stenosis shows a dilated ascending
aorta (white arrow) that abnormally projects farther
to the right than the right heart border. This is caused by
post-stenotic dilatation of the aorta.
For these same photos without the arrows, click here and here
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