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🔍 ARSA (Aberrant Right Subclavian Artery) – Overview and UK NHS/NICE Management
🫀 What is ARSA?
ARSA is an anatomical variant where the right subclavian artery arises abnormally as the last branch of the aortic arch and passes behind the trachea and oesophagus. It occurs in 0.5–2% of the population.
🧬 Associations:
| Type | Details |
|---|---|
| Isolated ARSA | Most common. Often benign. Usually requires no intervention. |
| Chromosomal abnormalities | Especially Trisomy 21 (Down syndrome), also 22q11.2 deletion syndrome (DiGeorge). Risk increases if ARSA is not isolated. |
| Structural anomalies | Congenital heart disease (e.g., VSD), vascular rings, or other arch anomalies may coexist. |
🩺 Antenatal Detection (e.g., 20-week scan or fetal echo):
If ARSA is seen, antenatal management depends on whether it is isolated or associated with other findings.
✅ Isolated ARSA:
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No need for invasive testing if:
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Nuchal translucency was normal
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No soft markers or structural anomalies
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NIPT/combined screening was low risk
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Document and inform paediatrics at birth for possible echo if indicated.
⚠️ ARSA + Other Findings (e.g., SGA, cardiac defects, echogenic bowel):
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Refer to Fetal Medicine Unit (FMU)
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Offer:
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Detailed anomaly scan
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NIPT or amniocentesis if high risk
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Possibly a fetal echocardiogram
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👶 Postnatal Management in the UK (NICE/NHS approach):
| Scenario | Management |
|---|---|
| Well term neonate, isolated ARSA suspected antenatally | - Routine neonatal exam- Consider cardiology referral or echo per local policy- Monitor for symptoms (feeding, stridor) |
| Feeding difficulties / stridor / noisy breathing | - Referral to paediatric cardiology and ENT- Likely CT angiogram or MRI to assess for compression |
| ARSA + other anomalies | - Full workup (genetics, echo, developmental follow-up) |
🚨 Symptoms to Watch Postnatally (Rare):
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Dysphagia lusoria (difficulty swallowing due to oesophageal compression)
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Stridor, chronic cough
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Recurrent respiratory infections
📘 UK References:
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NICE guidelines (Antenatal care: NG201)
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UK Fetal Anomaly Screening Programme (FASP)
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RCOG Green-top Guidelines
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BCCA (British Congenital Cardiac Association) – ARSA management consensus
Would you like a parent handout, echo referral template, or a summary letter for documentation?
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