Structural heart defects Flashcards
What is Tetralogy of Fallot?
congenital cardiac malformation. It is the most common form of congenital cyanotic heart disease.
Epidemiology of TOF
- TOF accounts for up to 10% of congenital cardiac abnormalities, making it the most common cyanotic heart defect.
- Typically manifests at 1-2 months of life
RFs of TOF
- Family history of congenital heart disease
- Rubellainfection
- Alcohol consumption in pregnancy
- Diabetic mother
- Down syndrome: trisomy 21
- DiGeorge syndrome: chromosome 22q11 deletion
- Edwards’ syndrome
What does TOF cause?
- Pulmonary stenosis: RV outflow obsruction - harder for deoxygenated blood to get into pulmonary circulation
- RV hypertrophy: To push blood past stenosis
- VSD: Blood shunts between ventricles - RV hypertrophy means pressure on right higher than left so blood shunted from right to left > deoxygenated blood enters LV and systemic circulation
- Overriding aorta: More deoxygenated blood in aorta
What happens as a result of this pulmonary stenosis
- cyanosis
- clubbing
- difficulty feeding
- failure to gain weight
In early neonatal period, how is pulmonary stenosis compensated for?
Patent ductus arteriosus - allow deoxygenated blood to enter pulmonary circultion - ductus arteriosus closes around day 2 and they start to be come symptomatic
What are Tet spells/ hypercyanotic spells
cyanosis is exacerbated as the infants demand for oxygen increase (e.g. when crying or feeding). Their heart will try to pump more (deoxygenated) blood, leading to a sudden decrease in oxygen saturation
How do infants respond to tet spells
Bring knees to chest like theyre squatting
Signs of TOF
- Ejection systolic murmur: due to pulmonary stenosis
- Reduced SpO2, particularly when distressed
- Respiratory distress
- Cyanosis
- Clubbing
Symptoms of TOF
- Poor weight gain or ‘failure to thrive’
- Difficulty feeding
- Hypercyanotic or ‘tet’ spells: cyanosis, breathlessness and syncope, particularly when crying or feeding
- Squatting posture
Investigations and diagnosis
- ECG
- Echo + doppler flow studies
- Chest X ray
Hypercyanotic tet spells management
- Conservative
- Oxygen
- BBs
- IV fluids
- Morphine
Neonatal cyanosis management
Prostaglandin e.g.alprostadil: used in symptomatic babies at birth to maintain a ductus arteriosus, thus allowing shunting of deoxygenated blood into the pulmonary circulation
Definitive management of TOF
- Blalock-Taussig (BT) shunt: atemporarypalliative measure performed for patients that remain persistently cyanotic whilst awaiting definitive surgery. It increases pulmonary arterial blood flow.
- Definitive surgery
Complications of TOF
- Tet spells
- Congestive Cardiac failure
- Arrhythmias
- Pulmonary regurgitation