Congenital vascular abnormality presenting as life-long asthma.

A female in her early 40s with a lifelong asthma diagnosis presented with worsening exertional dyspnoea and a dry cough despite being medically optimised. A clinical review revealed inspiratory stridor and swallowing difficulties, prompting further investigations. Spirometry showed an obstructive pattern and an elevated Empey index. This, along with a supporting flow-volume loop, raised suspicion of upper airway obstruction. Subsequent CT imaging (including an aortic angiogram) revealed a right-sided aortic arch with an aberrant left subclavian artery arising from a Kommerrell diverticulum. This formed a vascular ring compressing the trachea and oesophagus. Surgical intervention resulted in significant symptomatic and physiological improvement, with a markedly increased FEV1 and peak expiratory flow on repeat spirometry. This case highlights the importance of reconsidering diagnoses in patients unresponsive to standard therapy and the diagnostic utility of the Empey Index and flow-volume loops when identifying conditions mimicking asthma.