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aortic_stenosis

aortic stenosis

Introduction

  • 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

Aetiology

  • congenital biscuspid aortic valve
    • affects 1-2% of the population
    • 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 1):
      • Andersons syndrome with mutations in the gene KCNJ2
      • non-syndromic familial cases due to mutations in either:
        • NOTCH1
        • GATA5
        • SMAD6
  • calcification of a normal valve
    • atherosclerosis hence risk factors are:
    • 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 2)
  • 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 3)

Clinical features

  • most patients are asymptomatic for many years until it becomes more severe
  • decreased exercise tolerance
  • SOBOE
  • exertional dizziness or syncope
  • chest pain on exertion
  • auscultation may reveal:
    • a harsh, crescendo-decrescendo murmur in systole (best heard in right 2ICS) that radiates to the carotids
    • 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
  • 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
    • extension of calcification into conduction system may cause LBBB

Diagnosis

  • 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 cm2 4) and mean gradient > 40mmHg

Mx

  • 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.

Prognosis

  • 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
aortic_stenosis.txt · Last modified: 2019/03/16 10:12 by wh