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← Section IV · Congenital Heart Disease
IV.A

Complex Congenital Heart Disease

22 cards

Notes

Tetralogy of Fallot (TOF)

Four components (Fallot 1888):

  1. Large perimembranous VSD (unrestrictive).
  2. Overriding aorta (over the septum).
  3. Right ventricular outflow tract obstruction (infundibular ± valvular PS).
  4. Right ventricular hypertrophy (consequence of RVOT obstruction).
  • Most common cyanotic CHD to reach adulthood if unrepaired (few do; median untreated life ~12 y).
  • "Tet spells" (hypercyanotic episodes) - treated with knee-chest position, oxygen, fluids, morphine, phenylephrine, propranolol.
  • Repair: VSD closure + RVOT enlargement (± transannular patch → free PR).
  • Post-repair: chronic PR is universal; RV dilation progresses; pulmonary valve replacement often needed years later.

d-Transposition of the great arteries (d-TGA)

  • Aorta arises from RV, PA arises from LV - parallel circulations, incompatible with life without mixing (PDA, PFO, VSD).
  • Cyanosis in the newborn immediately.
  • Surgical repair options:
    • Arterial switch (Jatene, 1976) - current standard: great arteries switched with coronary reimplantation. Concerns: neo-aortic root dilation, coronary ostial stenosis, branch PA stenosis.
    • Atrial switch (Mustard or Senning) - historical: atrial-level baffle so systemic venous blood goes to LV → PA and pulmonary venous blood goes to RV → aorta. RV remains systemic ventricle → late RV failure, tricuspid regurgitation, atrial arrhythmias, sinus node dysfunction.
    • Rastelli - for TGA + VSD + PS: baffle LV to aorta through VSD; RV-to-PA conduit.

Congenitally corrected TGA (cctga / L-TGA)

  • Double discordance: AV discordance (RA→morphologic LV, LA→morphologic RV) AND VA discordance (mLV→PA, mRV→aorta).
  • Blood flow is physiologically normal, but the RV is systemic → late RV failure and systemic AV valve (tricuspid) regurgitation.
  • High risk of complete heart block (rate ~2 %/year); frequent Ebstein-like malformation of the systemic (tricuspid) AV valve.

AV canal / AVSD

  • Result of failure of endocardial cushion development.
  • Types:
    • Partial - primum ASD + cleft AMVL, common in Down syndrome.
    • Transitional - primum ASD + inlet VSD, but two distinct AV valves.
    • Complete - primum ASD + inlet VSD + common AV valve.
  • Rastelli classification of common AV valve based on chordal attachment (A/B/C).
  • Repair in infancy for complete AVSD to prevent Eisenmenger.

Truncus arteriosus

  • Single common arterial trunk arising from both ventricles, supplying systemic, pulmonary, and coronary circulations, over a large VSD.
  • Truncal valve is often abnormal (bicuspid or quadricuspid); frequent truncal insufficiency.
  • Types (Collett-Edwards) based on origin of pulmonary arteries.
  • Pulmonary overcirculation and CHF within days-weeks as PVR falls.
  • Surgical repair: VSD closure + RV-to-PA conduit + closure of PA off aorta.

Tricuspid atresia

  • Absent tricuspid valve; hypoplastic RV; obligate ASD for RA-to-LA flow.
  • Coexisting VSD directs LV output to the small RV and PA.
  • Cyanotic - degree depends on VSD size and pulmonary blood flow.
  • Palliation → Fontan.

Ebstein's anomaly

  • Apical displacement of the septal (± posterior) leaflet of the tricuspid valve by > 8 mm/m² BSA or > 20 mm.
  • Atrialization of the proximal RV.
  • Redundant, sail-like anterior TV leaflet.
  • Frequently associated with an ASD or PFO (leading to right-to-left shunting and cyanosis).
  • ~25 % associated with WPW (accessory pathway on the tricuspid annulus).

Single-ventricle physiology and the Fontan operation

  • Indications for Fontan: HLHS, hypoplastic RV syndromes, tricuspid atresia, mitral atresia, double-inlet or double-outlet single ventricle, complex AVSD with straddling.
  • Fontan concept: direct systemic venous blood to the pulmonary arteries WITHOUT a pumping chamber in the pulmonary circuit.
  • Modern variant: total cavopulmonary connection - SVC and IVC baffles directly to PAs.
  • Requires low PVR; high PVR → Fontan failure.
  • Late complications: protein-losing enteropathy, plastic bronchitis, Fontan-associated liver disease, atrial arrhythmias, systemic AV valve regurgitation.

Total anomalous pulmonary venous connection (TAPVR)

  • All 4 PVs drain to systemic venous circulation. Requires an obligate ASD.
  • Types:
    • Supracardiac (~45 %) - via vertical vein to innominate vein.
    • Cardiac (~26 %) - to coronary sinus.
    • Infracardiac (~24 %) - through diaphragm to portal/hepatic vein; usually obstructed (surgical emergency).
    • Mixed (~5 %).
  • Echo features: large RV, small LV, R-to-L shunt at ASD (always present), possible complex ventricular anatomy.

Cards

  • basicIV.A-001
    State the four anatomic components of tetralogy of Fallot.
    → 1) Large perimembranous VSD (unrestrictive). 2) Overriding aorta over the septum. 3) Right ventricular outflow tract obstruction (typically infundibular + valvular PS). 4) Right ventricular hypertrophy (consequence).
  • basicIV.A-002
    How is a hypercyanotic 'tet spell' managed acutely?
    → Knee-chest position (increases SVR → reduces R-to-L shunt), oxygen, fluid bolus, morphine, phenylephrine (α-agonist to raise SVR), and propranolol (decreases infundibular spasm).
  • basicIV.A-003
    What is the most common valvular complication after TOF repair, and how is it managed long-term?
    → Chronic free pulmonary regurgitation from a transannular RVOT patch. RV dilation progresses; pulmonary valve replacement (surgical or percutaneous) is often needed.
  • basicIV.A-004
    In d-TGA, from which ventricle does each great artery arise?
    → Aorta arises from the RIGHT ventricle. Pulmonary artery arises from the LEFT ventricle. This creates parallel circulations incompatible with life without mixing (PDA, PFO, VSD).
  • basicIV.A-005
    Which repair is now standard for simple d-TGA and when is it performed?
    → Arterial switch operation (Jatene, 1976) — great arteries switched at the level of the sinotubular junction with coronary reimplantation. Typically performed in the neonatal period (first 2 weeks of life).
  • basicIV.A-006
    Late complications of the arterial switch operation for d-TGA?
    → Neo-aortic root dilation, neo-aortic valve regurgitation, coronary ostial stenosis, branch pulmonary artery stenosis.
  • basicIV.A-007
    Long-term problems after a Mustard or Senning atrial-switch operation for d-TGA?
    → The morphologic RV remains the systemic ventricle → late RV failure, systemic AV (tricuspid) valve regurgitation, sinus node dysfunction, atrial arrhythmias, and baffle stenosis or leaks.
  • basicIV.A-008
    Describe the Rastelli procedure and its indications.
    → For d-TGA + VSD + LV outflow obstruction (PS). LV output is baffled through the VSD to the aorta; an RV-to-PA conduit is placed.
  • basicIV.A-009
    Explain 'double discordance' in congenitally corrected TGA (cctga / L-TGA).
    → AV discordance (RA connects to morphologic LV, LA connects to morphologic RV) AND VA discordance (morphologic LV connects to PA, morphologic RV connects to aorta). Blood flow is physiologically normal, but the morphologic RV serves as the systemic ventricle.
  • basicIV.A-010
    What are the major long-term problems with cctga?
    → Progressive failure of the systemic morphologic RV, systemic AV valve regurgitation (often Ebstein-like tricuspid valve), and complete heart block (rate ~2%/year).
  • basicIV.A-011
    Name the three main types of AV canal defect.
    → Partial (primum ASD + cleft AMVL only). Transitional (primum ASD + inlet VSD but two separate AV valves). Complete (primum ASD + inlet VSD + common AV valve).
  • basicIV.A-012
    Which congenital lesion is most classically associated with Down syndrome?
    → Complete atrioventricular canal defect (AVSD).
  • basicIV.A-013
    Truncus arteriosus — describe the basic anatomy.
    → Single common arterial trunk arises from both ventricles (astride a large subarterial VSD) and gives rise to the coronary arteries, pulmonary arteries, and aorta. The truncal valve (bicuspid or quadricuspid) is often abnormal — insufficiency is common.
  • basicIV.A-014
    Classic echo triad of tricuspid atresia?
    → 1) No visible tricuspid valve — a solid tissue band replaces it. 2) Small, hypoplastic RV. 3) Obligate atrial-level right-to-left shunt (ASD or PFO). A VSD or PDA usually supplies pulmonary flow.
  • basicIV.A-015
    State the key echo criteria for Ebstein's anomaly.
    → Apical displacement of the septal tricuspid leaflet > 8 mm/m² BSA (or > 20 mm absolute); atrialization of the proximal RV; redundant sail-like anterior TV leaflet. Often with PFO/ASD and right-to-left shunting.
  • basicIV.A-016
    What percentage of Ebstein's anomaly patients have Wolff-Parkinson-White syndrome?
    → ~25%. The accessory pathway is located on the tricuspid annulus.
  • basicIV.A-017
    State the goals of the Fontan operation.
    → 1) Separate systemic and pulmonary circulations. 2) Remove volume load from the single functional ventricle. 3) Direct systemic venous blood passively to the pulmonary arteries (no pumping chamber in the pulmonary circuit).
  • basicIV.A-018
    List three prerequisites for a successful Fontan operation.
    → Low pulmonary vascular resistance, preserved single-ventricular function, and unobstructed pulmonary artery anatomy. High PVR predicts Fontan failure.
  • basicIV.A-019
    Give three late complications of the Fontan operation.
    → Protein-losing enteropathy, plastic bronchitis, Fontan-associated liver disease, atrial arrhythmias, thromboembolism, and systemic AV valve regurgitation.
  • basicIV.A-020
    List the four anatomic types of TAPVR and their approximate frequencies.
    → Supracardiac (~45%) via vertical vein to innominate. Cardiac (~26%) to coronary sinus. Infracardiac (~24%) through diaphragm to portal/hepatic system — usually obstructed. Mixed (~5%).
  • basicIV.A-021
    Which type of TAPVR is a surgical emergency?
    → Infracardiac (infradiaphragmatic) TAPVR — the anomalous veins pass through the diaphragm and are almost invariably obstructed as they course through the liver.
  • basicIV.A-022
    Echo features of TAPVR?
    → Large right ventricle, small left heart, right-to-left atrial-level shunt (ASD is always present), and possibly complex ventricular anatomy (single ventricle).