Cardiovascular Disorders

Congenital Heart Disease

Clinical overview and exam mastery guide for shunt physiology, ductus arteriosus pharmacology, cyanotic lesion stabilization, and Eisenmenger progression.

Core Concept
Structural defect at birth
Shunt Direction
Left-to-right vs right-to-left
PDA Strategy
Close or keep open by indication
Cyanosis Marker
Right-to-left flow

Ductus Arteriosus Decision Axis

Need PDA closed Indomethacin or ibuprofen lower prostaglandin effect Need PDA open Alprostadil (PGE1) maintains ductal patency Long-standing left-to-right shunt can reverse Pulmonary hypertension progression leads to Eisenmenger physiology

Same structure, opposite pharmacologic goals depending on lesion context.

1. What Is Congenital Heart Disease (CHD)?

Congenital heart disease is a structural cardiac defect present at birth. High-yield exam focus includes shunt direction, ductus arteriosus management, and stabilization of cyanotic neonatal lesions.

2. Major Left-to-Right Shunts

  • Atrial septal defect (ASD)
  • Ventricular septal defect (VSD)
  • Patent ductus arteriosus (PDA)
  • Increase pulmonary blood flow
  • Can progress to pulmonary hypertension
  • Late reversal risk: Eisenmenger syndrome

3. Patent Ductus Arteriosus (PDA)

The ductus arteriosus connects pulmonary artery to aorta in fetal life and should close after birth. Persistent patency produces abnormal shunt flow.

Closure Drug MOA Major Side Effects Contraindications
Indomethacin NSAID COX inhibition lowers prostaglandin levels and promotes ductal closure Renal impairment, GI bleeding, NEC risk in neonates Renal failure, thrombocytopenia, high bleeding risk
Ibuprofen NSAID with similar prostaglandin-lowering closure mechanism Renal dysfunction, GI effects, bleeding risk Renal impairment and major bleeding risk states

4. Keeping Ductus Open (Life-Saving in Selected Defects)

In some cyanotic lesions, maintaining ductal patency is required until surgery (for example, transposition of the great arteries).

Prostaglandin E1 (Alprostadil)

  • MOA: relaxes ductal smooth muscle and keeps the ductus arteriosus open
  • Major side effects: apnea, hypotension, fever
  • Use: neonatal stabilization bridge to definitive intervention

5. Major Cyanotic Defects (Right-to-Left Shunts)

  • Tetralogy of Fallot
  • Transposition of the great arteries
  • Tricuspid atresia

Tetralogy of Fallot Components

  • VSD
  • Pulmonary stenosis
  • Overriding aorta
  • RV hypertrophy

Hypercyanotic (Tet) Spell Management

  • Knee-to-chest positioning
  • Supplemental oxygen
  • Morphine

Morphine reduces sympathetic outflow and infundibular spasm. Monitor for respiratory depression and hypotension.

6. Eisenmenger Syndrome

Long-standing left-to-right shunt may cause progressive pulmonary vascular disease, eventually reversing to right-to-left flow with cyanosis.

Pulmonary hypertension management Avoid pregnancy

7. Endocarditis Prophylaxis in CHD

  • High-risk defects may need prophylaxis before selected dental procedures
  • Standard agent: amoxicillin
  • MOA: beta-lactam inhibition of bacterial cell wall synthesis
  • Contraindication: serious beta-lactam allergy

Management Recap Drill

PDA closure: indomethacin or ibuprofen.
Need ductus open: start prostaglandin E1.
Tet spell: knee-to-chest, oxygen, morphine.
Eisenmenger: manage pulmonary hypertension and avoid pregnancy.

Visual Algorithm Placeholder

[Insert Congenital Heart Defect Classification and PDA Management Diagram Here During UI Integration]

Guideline References (Management)

AHA/ACC Adult Congenital Heart Disease Guidelines

https://www.acc.org/guidelines

Guideline Scope

  • PDA management and stabilization
  • Cyanotic defect strategy and surgical timing
  • Endocarditis prophylaxis indications

8. Common Exam Traps

Indomethacin closes PDA.
Prostaglandin E1 keeps PDA open.
Tet spells: oxygen plus morphine is a classic acute step.
Untreated long-standing shunt can evolve to Eisenmenger.
Cyanosis generally indicates right-to-left shunt physiology.

9. Quick Revision Summary

Must Remember

  • Left-to-right shunts increase pulmonary flow and volume load
  • Right-to-left shunts cause cyanosis
  • PDA strategy depends on lesion goals
  • Prostaglandin keeps ductus open, NSAIDs promote closure

Practice Questions Placeholder

  • Topic: Congenital Heart Disease
  • Subtopics: PDA, tetralogy of Fallot, cyanotic defects, prostaglandin use, Eisenmenger