Cardiovascular System >
Congenital Heart Disease (CHD)

“Conditions that arise as a result of abnormal development of the fetal heart”

  • Include:
    • Ventricular Septal Defects (VSD)
    • Patent Ductus Arteriosus (PDA)
    • Coarctation of the aorta
  • Tetralogy of Fallot: Combination of Coarctation of the aorta, overriding aorta, VSD, and right ventricular hypertrophy
Risk Factors
  • Modifiable:
    • Alcohol during pregnancy
    • Smoking during pregnancy
    • Poor nutrition during pregnancy
  • Non-Modifiable:
    • Maternal obesity
    • Infections in pregnancy (especially Rubella)
    • Closely related parents
    • Genetic defects (e.g Down’s syndrome, Marfan Syndrome)
Aetiology
  • Exact aetiology unknown
  • Involves disruption to the order of complex processes (including cell growth, migration and apoptosis) that lead to formation of the heart in the fetus during the 3rd and 4th weeks of fetal development.
Pathophysiology
  • Ventricular Septal Defects:
    • incomplete closure of the ventricular septum → left-to-right shunt of oxygenated blood at high pressure → increased pulmonary BP → pulmonary hypertension
  • Patent Ductus Arteriosus:
    • Incomplete closure of ductus arteriosus → flow of oxygenated blood from the aorta to the pulmonary artery → reduced stroke volume → tachycardia and breathlessness
Clinical Presentation
  • CHDs can be categorised as either cyanotic (right-to-left shunt) or acyanotic (left-to-right shunt), as peripheral cyanosis can be a distinguishing feature of many CHDs.  
    • Cyanotics – Truncus arteriosus (Fused aorta and pulmonary artery), Transposition of the great vessels and tricuspid atresia  
    • Acyanotics – PDA, VSDs* and ASDs. *May become cyanotic if left untreated
  • Other signs include:
    • Breathlessness
    • Tachycardia
    • Failure to thrive
    • Heart murmurs
    • Clubbing (in adulthood)
  • Often signs and symptoms only present after several years.
Investigations
  • Examination:
    • Auscultation – murmurs
  • Bloods: n/a
  • Imaging:
    • Chest X-Ray – Any cardiomegaly?
    • Fetal echocardiography – abdominal/transvaginal USS in 2nd trimester
  • Special:
    • Pulse oximetry –  reduced O2 sats
Management
  • Conservative:
    • 95% of Septal defects spontaneously fuse
  • Medical:
    • Diuretics (elimination of salts/water)
    • Digoxin (negative chronotrope, positive inotrope)
  • Surgical:
    • Closure of septal defects
    • Transcatheter Pulmonary valve insertion for RVOT defects
Complications
  • Developmental delays
  • Respiratory tract infections
  • Arrhythmias
  • Endocarditis
  • Pulmonary hypertension
  • Pulmonary Embolism
  • Sudden cardiac death.

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