Congenital Heart Disease

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CHD Overview - Embryo's Oopsies

  • Incidence: Affects ~8-10 per 1000 live births.
  • Critical Embryonic Period: Weeks 3-8 post-conception; crucial for cardiac organogenesis, especially septation and valve formation.
  • Etiology: Complex interplay; often unknown.
    • Genetic Factors: Chromosomal anomalies (e.g., Trisomies 13, 18, 21), single gene defects (e.g., Noonan syndrome), syndromes (e.g., Turner, DiGeorge 22q11.2 del).
    • Environmental Triggers: Maternal infections (e.g., rubella), metabolic conditions (e.g., diabetes, PKU), teratogens (e.g., alcohol, thalidomide, lithium, phenytoin, retinoic acid).

Fetal development timeline and sensitivity to defects

CHD Classification:

⭐ Ventricular Septal Defect (VSD) is the most common congenital heart defect overall (excluding bicuspid aortic valve).

Acyanotic CHD - No Blue Babies

ASD, PDA, VSD locations and L-R shunt direction

All feature L→R shunts initially. Complications: Pulmonary hypertension, Eisenmenger syndrome (late cyanosis), heart failure.

DefectLocation/TypeMurmurCXR FindingsAssociations
Ventricular Septal Defect (VSD)Membranous (commonest)Holosystolic, LLSBCardiomegaly, ↑pulmonary vascularityDown syndrome
Atrial Septal Defect (ASD)Ostium secundum (commonest)Wide, fixed split S2; ejection systolic murmur ULSBCardiomegaly, ↑pulmonary vascularityHolt-Oram syndrome
Patent Ductus Arteriosus (PDA)Aorta-Pulmonary Artery connectionContinuous machinery murmur 📌 (Gibson's), infraclavicularCardiomegaly, ↑pulmonary vascularityCongenital rubella, prematurity
-   Types: Infantile (preductal), Adult (postductal).
-   Clinical: BP ↑ upper limbs, ↓ lower limbs; weak/delayed femoral pulses.
-   CXR: Rib notching, "3" sign.

⭐ Continuous machinery murmur is characteristic of Patent Ductus Arteriosus (PDA).

Cyanotic CHD - Code Blue Kids

Characterized by Right-to-Left (R→L) shunts, causing early cyanosis and ↓ $O_2$ saturation.

FeatureTetralogy of Fallot (ToF)Transposition of Great Arteries (TGA)
Defect📌 PROVe: Pulmonary stenosis, RVH, Overriding aorta, VSD (R→L shunt)Aorta from RV, PA from LV (Parallel circuits; needs shunt for survival)
CXRTetralogy of Fallot: Boot-Shaped Heart CXR Boot-shapedEgg-on-a-string sign in TGA CXR Egg-on-string
Clinical"Tet spells" (cyanosis, hyperpnea) on crying/exertionSevere cyanosis from birth; PGE1 for PDA patency

CHD Complications & Syndromes - Hearts' Hurdles

  • Eisenmenger Syndrome:
    • Definition: Irreversible ↑Pulmonary Vascular Resistance (PVR) → R→L shunt, late cyanosis.
    • Pathophysiology:
*   Clinical Features: Dyspnea, palpitations, hemoptysis, RV failure.
![Eisenmenger syndrome pathophysiology](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Pathology_Cardiac_Pathology_Congenital_Heart_Disease/9fab743d-e04c-42d2-985a-0436d85a95ad.jpg)
  • Other Key Complications:
    • Infective Endocarditis: Prophylaxis for high-risk (unrepaired cyanotic CHD, prosthetic material, prior IE).
    • Polycythemia (secondary): Chronic hypoxia → ↑RBCs → hyperviscosity.
    • Brain Abscess: R→L shunts bypass lung filtration.
    • Paradoxical Embolism: Venous clot → systemic circulation via R→L shunt.
  • Associated Genetic Syndromes:
    SyndromeKey Associated CHD(s)
    Down (Trisomy 21)AVSD (Endocardial cushion defect), VSD
    Turner (XO)Coarctation of Aorta, Bicuspid Aortic Valve
    DiGeorge (22q11.2)Truncus Arteriosus, Tetralogy of Fallot
    MarfanAortic Root Dilatation, MVP

    ⭐ Endocardial cushion defects (AVSD) are strongly associated with Down syndrome (Trisomy 21).

High‑Yield Points - ⚡ Biggest Takeaways

  • Ventricular Septal Defect (VSD) is the most common CHD overall.
  • Tetralogy of Fallot (ToF) is the most common cyanotic CHD.
  • Eisenmenger syndrome signifies shunt reversal (L→R to R→L) causing late cyanosis.
  • Patent Ductus Arteriosus (PDA) presents with a continuous machinery murmur; closed by indomethacin.
  • Coarctation of Aorta is linked to Turner syndrome and rib notching.
  • Down syndrome is commonly associated with endocardial cushion defects (AVSD).
  • Paradoxical emboli can occur with Atrial Septal Defect (ASD) or PFO.

Practice Questions: Congenital Heart Disease

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Coarctation of aorta is most commonly associated with?

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Flashcards: Congenital Heart Disease

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_____ is a cardiac tumor associated with tuberous sclerosis

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_____ is a cardiac tumor associated with tuberous sclerosis

Rhabdomyoma

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