Hypoplastic L heart syndrome

Question 1

Embryology

Answer 1

• Underdevelopment of LV cavity: dynamic/progressive during gestation
  o Altered LV outflow → Ao stenosis
  o Altered LV inflow → MV stenosis or PFO stenosis
  o Spectrum of disease: from severe Ao stenosis or Ao atresia w intact IVS

Question 2

Gross exam

Answer 2

• Small, muscle bound LV
• Underdeveloped Ao (AV stenosis, atresia) → LVOTO
• Endocardial fibroelastoses: fibrosis of endocardium
  o Suspected from suprasystemic LVP
• Larger/prominent R sided structures: RA, RV, PA, TV, PV
  o RAE/RVE/H
• MV: patent or stenotic
• Severe: atretic AoV and MV, LV is non existent
• Mild: patent AoV and MV, LV hypoplasia

Question 3

Pathophys

Answer 3

• Growth.development of vascular structures depends on relative blood flow during fetal development
  o LVOTO: reversal of flow across PFO → ↓LV blood flow
  o Premature closure of PFO: ↓ LV preload → hypoplasia
• Not viable, no long term survivors
• PV flow → LA → PFO → PDA → systemic circulation
  o If restrictive PFO: ↑LAP → pulmonary edema

Question 4

C/s

Answer 4

24h after birth → depend on degree in PFO restriction
o Severe cyanosis
o Respiratory distress

Question 5

PE

Answer 5

• No murmur or soft basilar L ejection murmur
  o ↑ flow through PV

Question 6

ECG

Answer 6

• R axis deviation
• RAE → tall/peaked P waves

Question 7

CTX

Answer 7

• R sided cardiomegaly
• LAE

Question 8

Echo

Answer 8

• Small, muscle bound LV
  o Not extend to apex
• ↑ echo density of endocardial surface
• Small Ao, +/- patent
• Imperforated MV or thickened leaflets with short/absent pap muscles

Question 9

Natural hx

Answer 9

• Neonates will rapidly develop L-sided CHF secondary to ↑ LAP
• Survival can be extended if ASD or PDA

Question 10

Tx

Answer 10

o BVP in fetus to help LV blood flow
o PGE to maintain PDA patency
o Cardiac surgery or transplantation