aortic stenosis

see also:

• left ventricular hypertrophy (LVH)
• valvular_heart_disease

• this condition mainly presents in the elderly and is the most common heart valve disease in the elderly
• those with calcified biscuspid valves which accounts for 30-40% of cases, often present at age 40-60yrs
• AS affects 2% of those over 65yrs
• severe AS affects 5% of those over the age of 70yrs
• see also supravalvular aortic stenosis (SVAS) which is a congenital heart defect which occurs in 1 in 20,000 newborns worldwide due to mutations in the ELN gene which is inherited as AD pattern or develops as a spontaneous mutation

• those with congenital biscuspid aortic valve
  • affects 1-2% of the population
  • aortic calcification in those with a bicuspid valve is very different to that in those with a tricuspid valve
    • those with bicuspid valves develop calcification on BOTH sides of the valve and at an earlier age than those with a tricuspid vave who generally get calcification only on the aortic side and their disease mainly becomes an issue after age 60yrs ¹⁾
  • 35% will develop severe complications such as aortic stenosis, aortic regurgitation, SBE, ascending aorta aneurysms and aortic dissection
  • they calcify prematurely (usually presenting aged 40-60yrs) causing calcific aortic valvular disease and thus aortic stenosis
  • genetic causes ²⁾:
    • Andersons syndrome with mutations in the gene KCNJ2
    • non-syndromic familial cases due to mutations in either:
      • NOTCH1
      • GATA5
      • SMAD6
• rheumatic_fever
• calcification of a normal valve (tricuspid)
  • unlike in those with bicuspid valves, the calcification only occurs on the aortic side and usually is an issue in those over 60yrs age ³⁾
  • atherosclerosis hence risk factors are:
    • smoking, hypertension, high cholesterol, diabetes mellitus, and being male
  • there may be a genetic predisposition - 13% of the population have 1 single nucleotide polymorphism (SNP) rs10455872 in the lipoprotein(a) (LPA) locus which has been linked to CAVD thus an unusual type of cholesterol called Lp(a) — that is not normally screened for in current clinical practice — appears to be a cause of aortic valve disease ⁴⁾
• risk of aortic stenosis is doubled when patients had a first degree relative with aortic stenosis and tends to occur earlier in life, but the risk was 8x in those who also had ischaemic heart disease (IHD) which gives its own 4x risk factor for those without a FH of aortic stenosis ⁵⁾

• most patients are asymptomatic for many years until it becomes more severe
• decreased exercise tolerance
• SOBOE
• exertional dizziness or syncope
• chest pain on exertion
• congestive cardiac failure
• auscultation may reveal:
  • a harsh, crescendo-decrescendo murmur in systole (best heard in right 2ICS) that radiates to the carotids
    • this can be differentiated from the murmur of hypertrophic cardiomyopathy (HCM or HOCM) as AS murmur increases with squatting and decreases with standing or Valsalva
  • soft S2
  • S4 at apex
  • early systolic ejection click
  • may also have aortic_regurgitation
• sustained, heaving apex beat
• precordial thrill
• pulses are slowly rising and delayed
• BP has narrow pulse pressure
• ECG may show left ventricular hypertrophy (LVH)
• CXR may show:
  • LVH and possible LA enlargement
  • narrowing of retrocardiac space on lateral view
  • if calcified this may be visible
• associated conditions
  • Heyde's syndrome: angiodysplasia of the colon and lower GIT bleeding
  • may cause a form of von Willebrand disease by breaking down its associated coagulation factor due to turbulence around the valve
  • aortic_regurgitation
  • extension of calcification into conduction system may cause LBBB

• echocardiogram
  • the normal aortic valve area is 3-4 cm² and normal gradient is < 25mmHg
  • severe AS occurs when the aortic valve area (AVA) falls below 1.0 cm^{2 6)} and mean gradient > 40mmHg

• surgery if symptomatic
• it is no longer a recommendation for antibiotic prophylaxis to prevent SBE unless prosthetic heart valves, PH endocarditis, or certain congenital forms.

• without surgery, there is a >50% mortality in first 5 years (90% by 10 years) after it becomes symptomatic hence valve replacement surgery is usually indicated once it becomes symptomatic
  • 50% mortality is within 3yrs of syncope and within 2yrs of congestive cardiac failure due to AS