Internal Diseases and Therapy · MU Sofia

15. Diseases of the aortic valve: aortic stenosis

Explains aortic stenosis as a narrowing of the aortic valve that obstructs left ventricular outflow, then covers its causes, including calcific, bicuspid and rheumatic forms. It goes on to the haemodynamics, the classic symptoms and signs, and a severity table by echocardiographic parameters. Also included are a low-gradient classification, a differential diagnosis table, treatment indications, a TAVI versus surgical replacement comparison table, complications and prognosis.

Inside: 10 sections · 3 labelled pictures · 3 tables · 15 flashcards · 14 min

Topic 15 of 139 in the MU Sofia syllabus for Internal Diseases and Therapy (Medicine, Years 4 and 5). The free AceMed note covers it in 10 sections, about 1,766 words (14 min of reading), with 15 flashcards.

In this note

  1. Definition
  2. Etiology
  3. Pathophysiology and haemodynamics
  4. Classification
  5. Clinical features
  6. Diagnosis
  7. Differential diagnosis
  8. Treatment
  9. Complications
  10. Prognosis

Definition

Aortic stenosis (AS) is a narrowing of the aortic valve orifice that obstructs the outflow of blood from the left ventricle (LV) into the aorta, creating a systolic pressure gradient between the LV and the aorta.

  • The aortic valve normally has three cusps (right coronary, left coronary and non-coronary) and an area of 3–4 cm². The obstruction becomes severe at about 1 cm² or less.
  • AS is the most common valve disease needing intervention in Europe and North America, and its frequency rises steeply with age.
  • Obstruction of the LV outflow tract (LVOT) can also be subvalvular (membrane, hypertrophic obstructive cardiomyopathy) or supravalvular (Williams syndrome); this note deals with valvular AS.

Image: “Blausen 0040 AorticStenosis” by BruceBlaus, CC BY 3.0, via Wikimedia Commons.

Etiology

  • Calcific (degenerative) AS of a tricuspid valve: the most common cause in Europe, usually after 65–70 years. It is an active process resembling atherosclerosis (lipid infiltration, inflammation, then bone-like calcification) with the same risk factors: age, male sex, hypertension, smoking, diabetes, dyslipidaemia, high lipoprotein(a), chronic kidney disease. It starts as aortic sclerosis (thickened cusps without obstruction).
  • Bicuspid aortic valve: the most common congenital heart defect (1–2% of people, more often men). It stenoses earlier, typically at 50–65 years. It is associated with dilatation of the ascending aorta (risk of dissection), coarctation of the aorta and Turner syndrome, and may also cause aortic regurgitation and endocarditis.

Bicuspid aortic valve in the short-axis echo view: two cusps open like a clam shell (small drawings, closed to open) instead of the three-cusp "Mercedes star" of a normal valve.

Image: “Heart bicuspid aortic valve” by Patrick J. Lynch, medical illustrator, CC BY 2.5, via Wikimedia Commons.

  • Rheumatic AS: fusion of the commissures; almost always together with mitral valve disease; the main cause where rheumatic fever is common.
  • Rare: unicuspid valve (symptoms in youth), mediastinal radiotherapy, chronic kidney failure, Paget disease of bone, alkaptonuria, familial hypercholesterolaemia (supravalvular).

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