dilated aortic root

see also:

• thoracic aortic aneurysm
• vascular surgery
• aortic dissection
• abdominal aortic aneurysm (AAA)
• ANZSVS patient information on TAAs and AAAs

• the aortic root can be measured on echo or ECG-gated CT
• a dilated aortic root is a major risk factor for:
  • development of thoracic aortic aneurysm
  • aortic dissection

• the normal aortic root size is dependent upon age, gender, body surface area (BSA) and usually increases by 1mm per decade in normal adults
  • see 2013: Normal Limits in Relation to Age, Body Size and Gender of Two-Dimensional Echocardiographic Aortic Root Dimensions in Persons ≥15 Years of Age
  • as a rough guide, a size > 4cm but < 4.5-4.9cm is regarded as dilated and probably should have 1-2 yearly monitoring and good BP control
• a diameter greater than 4.5-4.9cm (depending on BSA, etc) is regarded as aneurysmal and needs 6-12 monthly monitoring

• mostly autosomal dominant disorder with reduced penetrance and variable expressivity caused by pathogenic variants in genes that affect the aortic wall
• less commonly can be can be X-linked or autosomal recessive
• genes with strong or definitive evidence for HTAD include FBN1, TGFBR1, TGFBR2, TGFB2, TGFB3, SMAD3, ACTA2, COL3A1, MYH11, MYLK, PRKG1, and LOX.
• genes with more limited or emerging evidence include FLNA, NOTCH1, MAT2A, SMAD2, BGN, ELN, FBN2, SLC2A10, EFEMP2, LTBP3, and THSD4
• genes affecting the aortic wall fall into three broad biological groups:¹⁾
  • extracellular matrix structure
    • Marfan syndrome (FBN1 gene)
    • vascular Ehlers-Danlos syndrome (COL3A1 gene)
    • non-syndromic HTAD
    • polycystic kidney disease (PKD1, PKD2)
    • MFAP5
    • MAT2A
  • TGF-β signaling
    • TGFBR1, TGFBR2, TGFB2, TGFB3, SMAD3, and SKI; TGFBR1, TGFBR2, TGFB2, TGFB3, and SMAD3 are well-established in this pathway, while SKI affects downstream TGF-β transcriptional regulation
    • Loeys-Dietz syndrome (TGFB3)
    • non-syndromic HTAD
  • vascular smooth muscle cell contraction
    • ACTA2, MYH11, MYLK, and PRKG1
    • non-syndromic HTAD

• bicuspid valve
• hypertension

• risk stratify into either:
  • “sporadic”
    • no family history, normal trileaflet aortic valve, or age-related changes
  • presence of bicuspid aortic valve (BAV):
    • associated with accelerated aortopathy
  • heritable thoracic aortic disease (HTAD):
    • genetic connective tissue conditions such as Marfan, Loeys-Dietz, or vascular Ehlers-Danlos syndromes
      • NB. those with Loeys-Dietz Syndrome often have aggressive disease and warrant closer monitoring and consideration for surgery if reaches 4.5cm (sometimes smaller)
    • a detailed family history of dissection, aneurysm, or sudden unexplained death is mandatory
• good BP control to slow rate of increase
  • maintain target BP < 130/80 mmHg
  • ACE inhibitors
  • +/- beta adrenergic blockers
• statin therapy is generally recommended if there is concurrent evidence of atherosclerosis
• complete cessation of cigarette smoking and nicotine is mandatory as nicotine appears to accelerate aortic wall degradation
• lifestyle modifications:
  • strictly avoid heavy weightlifting, straining, and intensive Valsalva-provoking maneuvers
  • encourage regular, low-to-moderate intensity dynamic aerobic exercises (e.g., brisk walking)
• ongoing monitoring of size:
  • consider an initial repeat scan in 6-12 months to exclude rapid enlargement
  • if this scan is stable then repeat scans every 1-3 years depending upon risk stratification
  • progression is considered rapid if growth is ≥ 0.3 cm/year over 2 consecutive years or ≥ 0.5 cm in a single year - this triggers immediate surgical referral
• Mx as per thoracic aortic aneurysm if size becomes aneurysmal (eg. > 4.5-4.9cm depending on gender, age, BSA)