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← Section IV · Congenital Heart Disease
IV.B

Aortic Valve, Aorta, and Subvalvular Outflow Tract

12 cards

Notes

Bicuspid aortic valve (BAV)

  • Most common congenital cardiac abnormality (1–2 % of the population).
  • Two functional cusps; often with a raphe (fusion of embryonic commissures).
  • Best identified in systole - a raphe may make a BAV look trileaflet in diastole.
  • Common phenotypes:
    • RCC–LCC fusion (~70 %) - anterior + posterior leaflets, horizontal closure line. Fewer aortic complications.
    • RCC–NCC fusion (20–30 %) - closure line runs anterior-posterior. Greater risk of ascending aortic dilation.
  • Associations: coarctation of the aorta (30–50 %), intracranial aneurysms.
  • BAV aortopathy:
    • Aortic root > 40 mm OR ascending aorta > 37 mm is abnormal.
    • Growth 0.4–0.6 mm/year.
    • ~20–30 % of first-degree relatives also have BAV.
    • Complete raphe → more AI and more root dilation.
  • Complications: aortic stenosis (calcification decades earlier than trileaflet AS), aortic regurgitation, endocarditis, aortic dissection.

Subvalvular AS

Subaortic membrane (discrete)

  • Fibrous ring in the LVOT below the aortic valve.
  • Progressive; AR develops from the jet damaging the aortic leaflets.
  • Associations: VSD, PDA, coarctation, Shone complex, BAV, persistent left SVC, PS.
  • Surgical excision indicated with at least moderate AR.

Tunnel-form subvalvular AS

  • Long-segment LVOT narrowing; more severe.

Supravalvular AS

  • Williams syndrome (elastin gene 7q11 deletion) - hourglass narrowing of the ascending aorta at/just above the sinotubular junction. Often with peripheral pulmonic stenosis and supravalvular PS.
  • Sporadic and familial forms also exist.

HLHS (hypoplastic left heart syndrome)

  • Spectrum of underdevelopment of left-sided structures: hypoplastic LV, hypoplastic ascending aorta, aortic and/or mitral atresia or stenosis.
  • Ductal-dependent systemic circulation.
  • Staged palliation:
    1. Norwood at birth - main PA reconstructed as neo-aorta; systemic-to-pulmonary shunt (BT or Sano).
    2. Bidirectional Glenn (~6 months).
    3. Fontan (~2–4 y).

Coarctation of the aorta

  • Narrowing in the upper descending thoracic aorta near the ductus arteriosus / ligamentum arteriosum.
  • Adult "post-ductal" coarctation - discrete shelf beyond left subclavian; often diagnosed as HTN in a young adult.
  • Neonatal (pre/juxta-ductal) - presents in infancy with critical obstruction as PDA closes.
  • Echo: suprasternal notch view shows narrowing; PW/CW distal to obstruction reveals persistent antegrade diastolic flow with a saw-tooth pattern (typical of significant coarctation).
  • Peak gradient > 20–30 mmHg (or a "run-off" pattern) is significant.
  • Associations: BAV, VSD, PDA, Turner syndrome.

Interrupted aortic arch

  • Complete anatomical interruption between two segments of the aorta.
  • Classified A (distal to left SCA), B (between LCC and left SCA - most common; 22q11 deletion), or C (between innominate and LCC).
  • Ductal-dependent for systemic flow below the interruption.

Cards

  • basicIV.B-001
    Approximate prevalence of bicuspid aortic valve in the general population?
    → 1–2%. Most common congenital cardiac abnormality.
  • basicIV.B-002
    Two most important non-valvular associations with BAV?
    → Coarctation of the aorta (30–50%) and intracranial (berry) aneurysms.
  • basicIV.B-003
    State BAV aortopathy dimensions on TTE.
    → Aortic root > 40 mm OR ascending aorta > 37 mm is abnormal. Growth rate typically 0.4–0.6 mm/year.
  • basicIV.B-004
    Which family-screening recommendation applies to BAV?
    → First-degree relatives should undergo echocardiographic screening — ~20–30% of first-degree relatives also have BAV.
  • basicIV.B-005
    List three associations of a subaortic membrane.
    → VSD, PDA, coarctation of the aorta, Shone complex, bicuspid AV, persistent left SVC, and pulmonic stenosis.
  • basicIV.B-006
    When should surgical excision of a subaortic membrane be performed?
    → When at least moderate aortic regurgitation has developed (from jet damage to the aortic leaflets). In young patients with non-calcified AV, repair is favored over replacement.
  • basicIV.B-007
    Genetic and cardiac features of Williams syndrome?
    → Elastin gene deletion (chromosome 7q11). Cardiac: supravalvular aortic stenosis (hourglass narrowing), supravalvular PS, peripheral pulmonic stenosis, and coronary ostial stenosis.
  • basicIV.B-008
    Name the four staged operations for hypoplastic left heart syndrome.
    → Wait — three stages: 1) Norwood (neonatal) — neo-aortic reconstruction using main PA + systemic-to-pulmonary shunt (modified BT shunt or Sano RV-PA conduit). 2) Bidirectional Glenn (SVC to PA, ~6 months). 3) Fontan (~2–4 years, IVC baffle to PA).
  • basicIV.B-009
    Where does coarctation of the aorta typically occur?
    → In the upper descending thoracic aorta, near the ductus arteriosus (or ligamentum arteriosum), just distal to the left subclavian artery origin.
  • basicIV.B-010
    What Doppler pattern in the descending aorta indicates significant coarctation?
    → Persistent antegrade DIASTOLIC flow with a saw-tooth (run-off) pattern distal to the obstruction, and a resting peak gradient > 20–30 mmHg. Absence of diastolic flow reversal proximally.
  • basicIV.B-011
    Most common form of interrupted aortic arch and its syndromic association?
    → Type B (between left common carotid and left subclavian) — most common. Strongly associated with 22q11 deletion (DiGeorge syndrome).
  • basicIV.B-012
    Why is a raphe important on a suspected bicuspid aortic valve?
    → A raphe (fibrous fusion of embryonic commissures) can make a BAV look trileaflet in diastole. The valve must be evaluated in SYSTOLE (during maximal opening) to accurately determine number of functional leaflets.