Congenital heart defects

CHD Basics - Blue vs. Pink Babies

• Acyanotic (L→R Shunt): Oxygenated blood shunts from the left to the right side of the heart. Leads to ↑ pulmonary blood flow. No initial cyanosis.
  • Examples: VSD, ASD, PDA.
• Cyanotic (R→L Shunt): Deoxygenated blood shunts from the right to the left, bypassing the lungs and entering systemic circulation.
  • Examples: Tetralogy of Fallot (ToF), TGA.
  • 📌 Mnemonic (5 T's): Tetralogy of Fallot, Transposition, Truncus Arteriosus, Tricuspid Atresia, TAPVR.

⭐ Ventricular Septal Defect (VSD) is the most common congenital heart defect diagnosed in children.

Acyanotic Defects - Leaky Heart Havoc

• Pathophysiology: Left-to-right shunts (L→R) leading to ↑ pulmonary blood flow & pressure. No initial cyanosis.
• Ventricular Septal Defect (VSD):
  • Most common CHD overall.
  • Harsh holosystolic murmur at lower left sternal border.
  • CXR: Cardiomegaly, ↑ pulmonary vascular markings.
• Atrial Septal Defect (ASD):
  • Wide, fixed splitting of S2.
  • CXR: Cardiomegaly with a prominent pulmonary artery.
• Patent Ductus Arteriosus (PDA):
  • Continuous “machinery” murmur at the left infraclavicular area.
  • Associated with congenital rubella.
  • Treatment: Indomethacin (closure) or Prostaglandins (to keep it patent).

⭐ Eisenmenger Syndrome: A late complication where chronic pulmonary hypertension reverses the shunt (R→L), causing cyanosis, clubbing, and polycythemia.

Cyanotic Defects - The Blue Crew

• Caused by right-to-left shunts, leading to early cyanosis (“blue babies”).
• 📌 Mnemonic: 1-2-3-4-5
  • 1 Trunk: Truncus Arteriosus
  • 2 Great Vessels: Transposition of the Great Arteries (TGA)
  • 3 Leaflets: Tricuspid Atresia
  • 4 Defects: Tetralogy of Fallot (TOF)
  • 5 Words: Total Anomalous Pulmonary Venous Return (TAPVR)
• Key X-Ray Findings:
  • TOF: "Boot-shaped" heart.
  • TGA: "Egg-on-a-string" appearance.
  • TAPVR (supracardiac): "Snowman" or "Figure-of-8" sign.

⭐ Tetralogy of Fallot is the most common cyanotic CHD overall. "Tet spells" (hypercyanotic episodes) are often relieved by squatting, which increases systemic vascular resistance.

Key Syndromes & Signs - X-Ray Vision

• Syndromic Associations:

  • Down Syndrome (Trisomy 21): Endocardial cushion defect (AVSD) is most common.
  • Turner Syndrome (XO): Bicuspid aortic valve, Coarctation of Aorta.
  • DiGeorge Syndrome (22q11.2): Conotruncal defects (Truncus arteriosus, TOF).
  • Noonan Syndrome: Valvular Pulmonary Stenosis.
  • Marfan Syndrome: Aortic root dilatation.

• Classic X-Ray Findings:

  • Tetralogy of Fallot (TOF): "Boot-shaped" heart (Coeur en sabot).
  • TGA: "Egg-on-a-string" sign.
  • TAPVC (Supracardiac): "Snowman" or "Figure of 8" sign.
  • Ebstein's Anomaly: "Box-shaped" heart (massive cardiomegaly).

⭐ Over 50% of children with Down Syndrome have a congenital heart defect, with Atrioventricular Septal Defect (AVSD) being the most characteristic lesion.

• VSD is the most common CHD overall; TOF is the most common cyanotic CHD.
• Classic X-ray findings: "boot-shaped heart" for Tetralogy of Fallot and "egg-on-string" sign for TGA.
• A continuous machinery murmur is pathognomonic for PDA.
• Eisenmenger syndrome is the irreversible reversal of a left-to-right shunt due to severe pulmonary hypertension.
• Down syndrome is strongly associated with AV septal defects (endocardial cushion defects).
• Maternal rubella infection is a major risk factor for PDA and pulmonary stenosis.