Cyanotic CHD Cheatsheet
Key Concept: TGA = parallel circuits, profound cyanosis at birth, no O2 response, single loud S2, egg-on-string CXR → PGE1 + balloon septostomy + arterial switch. TOF = boot-shaped heart, tet spells, PS murmur. Truncus = single vessel + VSD + DiGeorge. TAPVR = pulm veins to systemic; supracardiac = snowman CXR; infracardiac = obstructed emergency.
| Diagnosis |
Key Features |
| TGA |
- Aorta from RV (anterior), pulmonary artery from LV (posterior) — great vessel transposition
- Parallel circuits — oxygenated blood never reaches systemic circulation
- Profound central cyanosis from birth
- Single LOUD S2 (anterior aortic valve close to chest wall)
- No murmur (or soft if VSD present)
- O2 does NOT improve PaO2 — parallel circuits bypass lung oxygenation
- Egg-on-string/egg-on-side CXR (narrow mediastinum)
- PGE1 + balloon atrial septostomy → arterial switch (Jatene) within 2 weeks
|
| Tetralogy of Fallot |
- 4 defects: VSD + overriding aorta + pulmonic stenosis + RVH
- Boot-shaped heart (coeur en sabot) on CXR
- Harsh systolic ejection murmur at left upper sternal border
- Cyanosis degree depends on severity of pulmonic stenosis
- Hypercyanotic tet spells → knee-chest position + propranolol + morphine
- Complete surgical repair by 3–6 months of age
|
| Truncus Arteriosus |
- Single arterial trunk from both ventricles (failure of aortopulmonary septation)
- Always associated with VSD
- Single semilunar valve (may be regurgitant)
- DiGeorge syndrome (22q11 deletion) association
- Mixing occurs → less cyanotic than TGA
- CXR: increased pulmonary markings + cardiomegaly
- Early repair required before Eisenmenger physiology develops
|
| TAPVR |
- All 4 pulmonary veins drain to systemic venous system (not LA)
- Requires ASD for survival — obligatory R→L shunt at atrial level
- Supracardiac (SVC/innominate) = snowman/figure-8 CXR
- Infracardiac = obstructed → severe pulmonary edema
- Pulmonary venous hypertension → cyanosis + respiratory distress
- Emergent surgery for obstructed TAPVR
|
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