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Congenital cyanotic heart disease – most common cause of cyanosis after infancy
Congenital cyanotic heart disease – most common cause of cyanosis after infancy
Risk Factors
Chromosomal abnormalities:
Trisomy 21 (Down syndrome), Trisomy 18, Trisomy 13
22q11 deletion (DiGeorge syndrome)
Jagged1 gene mutation (Alagille syndrome)
NKX2.5 gene mutation
Family history:
1st-degree relative with congenital heart disease
Maternal factors:
Pre-gestational diabetes
Phenylketonuria (uncontrolled)
Aetiology
Developmental malformation of the conotruncal septum during cardiac embryogenesis
Multifactorial – genetic and environmental
Pathophysiology
Four anatomical abnormalities:
Pulmonary stenosis (right ventricular outflow tract obstruction)
Right ventricular hypertrophy (secondary to obstruction)
Overriding aorta (displaced over VSD)
Ventricular septal defect (VSD) – large, malaligned
Right-t-left shunt → deoxygenated blood enters systemic circulation → cyanosis
Degree of shunt determined by severity of pulmonary stenosis
Hypercyanotic (TET) spells:
Triggered by exertion, feeding, crying
Child becomes acutely cyanosed, floppy ± LOC
Older children may squat to increase systemic vascular resistance → reduce R→L shunt
Diagnosis
Presents within first 6–12 months
May be detected antenatally on fetal cardiac ultrasound
Clinical features:
Cyanosis
Clubbing (if chronic)
Harsh ejection systolic murmur (from RVOT stenosis)
TET spells
Differential Diagnosis
Other cyanotic congenital heart diseases:
Transposition of the great arteries
Tricuspid atresia
Total anomalous pulmonary venous return
Pulmonary atresia with intact septum
Non-cardiac:
Primary pulmonary disease
Sepsis
Investigations
Pulse oximetry – low saturations
Chest X-ray:
“Boot-shaped heart” (due to RVH + upturned apex)
ECG – right axis deviation, RV hypertrophy
Echocardiography (Doppler) – diagnostic gold standard
Cardiac MRI / CT angiography – anatomical detail pre-op
Cardiac catheterisation – pre-surgical planning
Management
Acute Management
If critically cyanotic at birth → prostaglandin E1 infusion to maintain ductus arteriosus
TET spells:
Knee-chest position (increases SVR)
Oxygen
Sedation (morphine), IV fluids
IV beta-blockers (e.g., propranolol or esmolol)
Intubation and paralysis if refractory
Surgical
Definitive repair by 6–12 months:
VSD closure + relief of RVOT obstruction
Palliative (if not fit for full repair initially):
Modified Blalock–Taussig shunt
RVOT balloon/stenting
Post-op care may include ECMO if severe instability
Long-term Management
Ongoing cardiology follow-up
Monitor for pulmonary regurgitation, RV dysfunction
May require valve replacement later in life
Infective endocarditis prophylaxis for high-risk procedures (e.g. dental)
Amoxicillin, ampicillin, or cephalexin as per local protocol
Complications & Prognosis
Acute
Recurrent TET spells
Hypoxic brain injury
Paradoxical emboli → stroke, brain abscess
Chronic / Post-operative
Pulmonary regurgitation → RV failure
Atrial/ventricular arrhythmias
Sudden cardiac death
Heart failure (late complication)
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