Flash Pulmonary Oedema in a Patient With Unilateral Renal Artery Stenosis and Preserved Contralateral Function: A Medically Managed Case Report.

Flash pulmonary oedema (Pickering phenotype) is a high-risk, under-recognised manifestation of renovascular disease. A man in his 50s presented with abrupt dyspnoea, hypertensive crisis, type 1 respiratory failure, and pulmonary oedema. His response to intravenous diuretics was limited, and he was stabilised in the ICU with glyceryl trinitrate and continuous positive airway pressure. Ultrasound showed a small scarred right kidney of 7.9 cm. Echocardiography found a left ventricular ejection fraction (LVEF) of 25% at presentation. Three months later, cardiac MRI showed LVEF of 40% with diffuse mid-wall scarring. Renal MR angiography (MRA) confirmed severe ostial right renal artery stenosis, and dimercaptosuccinic acid (DMSA) demonstrated a split kidney function of 36% in the right and 64% in the left. A medical-first strategy was chosen after multidisciplinary discussion, with no recurrent episodes of pulmonary oedema during follow-up. This case illustrates the difficulty of attributing flash pulmonary oedema to unilateral atherosclerotic renovascular disease in the context of long-standing hypertensive heart and kidney disease and highlights how laterality, kidney size, and differential function can guide the choice between selective revascularisation and conservative management.