AORTIC VALVE STENOSIS
(AS)
AETIOLOGY OF AORTIC VALVE STENOSIS
- There is an incomplete opening of the Aortic valve which restricts blood flow from the LV during Systole.
- It is the most common acquired valve disease in adults in developed countries.
- 1-2% of those > 65y have isolated calcific AS.
- 12% of those > 75y haave calcific AS (3.4% have severe AS)
- 29% exhibit age-related aortic valve sclerosis without stenosis:
- Defined as irregular thickening or calcifications of aortic valve leaflets.
- Found in 9% with mean age 54y and 42% with mean age 81)
- Defined as irregular thickening or calcifications of aortic valve leaflets.
- More common in men.
- Incidence increases with age.
- Prevalence:
- 65 - 75 years: 1.3%
- 75 - 85 years: 2.4%
- > 85 years: 4%
- Aortic valve orifice obstruction subjects the left ventricle to a long-term pressure overload.
- LV concentric hypertrophy gradually develops as an adaptive compensatory mechanism.
- This has a negative impact as it leads to:
- Development of left ventricular diastolic dysfunction.
- The classic triad of symptoms of significant aortic stenosis: (EFFORT ASD)
(b) Effort Syncope
(c) Effort Dyspnoea (and Fatigue)
- Concentric left ventricular hypertrophy is an independent risk factor for operative mortality at aortic valve replacement.
- In advanced AS:
- LV EF decreases.
- CO decreases.
- Pulmonary Hypertension increases.
- Symptoms of the CHF appear.
- Efficient medical treatment of aortic stenosis does not exist.
- Life expectancy with onset of symptoms is approximately 3 years, and only 1year in those after the onset of congestive heart failure.
- Surgical in-hospital mortality rate is approximately 3%.
AETIOLOGY
Congenital Aortic Stenosis:
- Two leading causes of AS prevalent in developed countries:
- Congenital Aortic Stenosis.
- Degenerative Aortic stenosis.
- Rheumatic Aortic Stenosis, (more prevalent in developing nation).
- Other causes remain extremely rare:
- Rheumatoid Heart Disease.
- Familiar Hypercholesterolemia.
- SLE (Systemic Lupus Erythematosus).
- Ochronosis.
Congenital Aortic Stenosis:
- Relatively common
- Incidence of 1–2%.
- Its haemodynamic severity varies.
- In critical aortic stenosis, symptoms may appear immediately after birth.
- May remain hemodynamically insignificant for a long time and first signs appear only in adulthood.
- It is most frequently a valvular stenosis.
- Subvalvular stenosis is rare and supra-valvular stenosis is extraordinarily rare.
- The aortic valve is bicuspid or, rarely, unicuspid
- Congenitally bicuspid aortic valve (stenosis and regurgitant) is frequently accompanied by gradually developing ascending aortic dilation.
- The aortic dilation is slow but constant and continues even after aortic valve replacement.
- It carries a high risk of aortic dissection.
Congenital Unicuspid Aortic Valve Stenosis
Congenital Aortic Valve Stenosis
Unicuspid Unicommissural Congenital Aortic Valve Stenosis (Aortic view)
(Slit-like orifice and cusps are penetrated with calcification)
(Slit-like orifice and cusps are penetrated with calcification)
Congenital Bicuspid Aortic Valve with Dilated Ascending Aorta
Subvalvular Aortic Valve Stenosis
a. Thickened cusps with mild retraction secondary to turbulent flow above the subvalvular stenosis
b. Subvalvular Membranous Aortic Stenosis
a. Thickened cusps with mild retraction secondary to turbulent flow above the subvalvular stenosis
b. Subvalvular Membranous Aortic Stenosis
Senile Degenerative Calcific Aortic Stenosis:
- The most common cause of AS.
- Is the most frequent cause for AVR.
- Results from prolonged exposure to mechanical stress over years in a normal valve.
- Mechanical stress leads to a process similar to atherosclerosis (also called aortic sclerosis).
- Proliferative and mechanical changes.
- Lipid accumulation.
- Upregulation of ACE activity.
- Infiltration of macrophages and T lymphocytes.
- Similar pathogenetic features favour the hypothesis that the main known risk factors for atherosclerosis are also risk factors for degenerative aortic stenosis:
- Elevated serum LDL Cholesterol.
- Diabetes.
- Smoking.
- Hypertension.
- CAD is commonly associated with AS.
- Age related aortic valve sclerosis is associated with increased risk of:
- Cardiovascular Death.
- MI.
- Progressive calcification initially along the flexion lines at the base of the leaflet.
- Discrete focal calcifications on the aortic side of the leaflets.
- Calcification often extend into the annulus, aortic root, sinuses of valsalva, ascending aorta and anterior mitral valve leaflet.
- Advanced stage there are extensive dystrophic calcification in the cusps.
- The commissures are not fused.
Senile Degenerative Calcified Aortic Valve Stenosis
(Calcification penetrates the cusps)
(Commirssures are not fused)
(Calcification penetrates the cusps)
(Commirssures are not fused)
Degenerative Aortic Valve Stenosis
Mixed Degenerative Aortic Valve Disease
(with cusp calcification)
(with cusp calcification)
Rheumatic Aortic Stenosis
- Least common form of AS in adults in the Western world.
- Results in rigid stenotic or steno-incompetent orifice.
- Characterised by diffuse fibrous leaflet thickening and scarred leaflet edges.
- Typically has fused one or more commissures.
- Disease progression is much slower than that of degenerative calcific disease.
- It rarely occurs as an isolated aortic.
- Usually occurs in conjunction with mitral valve stenosis Rheumatic aortic-mitral disease.
Rheumatic Aortic Valve Stenosis
Degenerative Rheumatic
Calcified Aortic Valve Stenosis
Calcified Aortic Valve Stenosis
Mixed Rheumatic Aortic valve Disease
(with fish-mouth narrow rigid orifice)
(with fish-mouth narrow rigid orifice)