Cyanotic Congenital Heart Disease (R-L Shunt)
Cyanotic heart defects occur when deoxygenated blood bypasses the lungs and enters the systemic circulation, leading to clinical cyanosis (hypoxemia).
1. The “5 Ts” of Cyanotic Heart Disease
- Tetralogy of Fallot (TOF): Most common cyanotic CHD.
- Transposition of the Great Arteries (TGA): Most common cause of cyanosis in the neonatal period.
- Truncus Arteriosus: A single large vessel arising from both ventricles.
- Tricuspid Atresia: Hypoplastic right ventricle.
- Total Anomalous Pulmonary Venous Return (TAPVR): Pulmonary veins drain into the right atrium.
2. Tetralogy of Fallot (TOF) – High-Yield Details
| Feature | Description |
|---|---|
| Components | VSD, Overriding Aorta, Pulmonary Stenosis, RV Hypertrophy. |
| Classic Sign | “Boot-shaped heart” on chest X-ray. |
| “Tet” Spells | Hypercyanotic episodes triggered by agitation/crying. |
3. Clinical Management
- Tet Spells: Immediate knee-chest position (increases systemic vascular resistance), supplemental O2, and morphine to reduce infundibular spasm.
- Prostaglandin E1: Essential for ductal-dependent lesions (e.g., severe TGA, Tricuspid Atresia) to maintain systemic perfusion until surgery.
NEET PG Hint: Remember: The knee-chest position in a Tet spell works by increasing systemic vascular resistance, which decreases the right-to-left shunt across the VSD, thereby increasing pulmonary blood flow. For more high-yield pediatric cardiology and free medical questions, visit mymedschool.org.