Abdominal Aortic Aneurysm: Causes

Pathogenesis (disease development)

Atherosclerosis (= intimal lesion/injury to the inner layer of a vessel) is the most common cause of aortic aneurysm (medial lesion/injury to the middle layer of a vessel). The pathogenesis is still very unclear. Of importance seems to be an increased activity of matrix metalloproteinases (MMPs) in affected patients. These regulate connective tissue homeostasis. Aneurysms of the abdominal aorta are located in up to 95% infrarenal (section located below the renal arteries). Iliac artery aneurysms are limited to the common iliac artery and internal iliac artery.

Etiology (Causes)

Biographic causes

  • Genetic burden – increased risk in first-degree relatives.
    • Genetic risk dependent on gene polymorphisms:
      • Genes/SNPs (single nucleotide polymorphism; English : single nucleotide polymorphism):
        • Genes: DAB2IP
        • SNP: rs7025486 in gene DAB2IP
          • Allele constellation: AG (1.2-fold).
          • Allele constellation: AA (1.4-fold)
        • SNP: rs10757278 in an intergenic region.
          • Allele constellation: GG (1.3-fold).
          • Genetic diseases genetic diseases allele constellation: AA (0.77-fold).
    • Genetic diseases
      • Ehlers-Danlos syndrome (EDS) – genetic disorders that are both autosomal dominant and autosomal recessive; heterogeneous group caused by a disorder of collagen synthesis; characterized by increased elasticity of the skin and unusual tearability of the same.
      • Loeys-Dietz syndrome – aortic aneurysm syndrome with autosomal dominant inheritance, which is caused by a mutation of the TGF-β receptor (98-100% of these patients have aneurysms)
      • Marfan syndrome – genetic disease, which can be inherited both autosomal dominant or occur sporadically (as a new mutation); systemic connective tissue disease, which is mainly notable for tall stature; 75% of these patients have an aneurysm
  • Gender: male (odds ratio 5.69) [S3 guideline].

Behavioral causes

  • Consumption of stimulants
    • Alcohol consumption – People with a genetic predisposition to alcohol consumption are 2.6 times more likely to suffer an abdominal aortic aneurysm (evidence from Mendelian randomization).
    • Nicotine abuse (odds ratio 2.41) [S3 guideline.]

Disease-related causes.

Congenital malformations, deformities and chromosomal abnormalities (Q00-Q99).

  • Anlage disorders of the aortic valve
  • Ehlers-Danlos syndrome (see “Biographical Causes” below).
  • Loeys-Dietz syndrome (see below “Biographical Causes”).
  • Marfan syndrome (see below “Biographical Causes”).

Respiratory system (J00-J99)

Cardiovascular system (I00-I99)

  • Arterial hypertension (high blood pressure) (+65%).
    • Systolic blood pressure: each 20 mmHg increase was associated with a 14% higher risk of abdominal aortic aneurysm (AAA)
    • Diastolic blood pressure: each increase of 10 mmHg was associated with a 28% higher risk of AAA (abdominal aortic aneurysm, AAA); diastolic pressure around 110 mmHg: risk of AAA around five times higher than values around 70 mmHg;
  • Atherosclerosis (arteriosclerosis, hardening of the arteries).
  • Vasculitis (vascular inflammation)

Infectious and parasitic diseases (A00-B99).

  • Aortitis, e.g., due to syphilis (lues).

Laboratory diagnoses – laboratory parameters that are considered independent risk factors.

  • Hypercholesterolemia

Medication