A 73 year old man presented to the emergency department with a three day history of dyspnoea. He had no past medical history. On admission his blood pressure was 120/80 mmHg, heart rate 120 bpm, and respiratory rate 24 breaths per minute. On auscultation inspiratory crackles were heard over the mid and upper portion of the right hemi-thorax along with a minor systolic heart murmur.

Apart from sinus tachycardia, the ECG was unremarkable. An infiltrate in the upper lobe of the right lung was seen on a standard chest x ray. The echocardiogram showed a partially flailed posterior mitral leaflet caused by ruptured chordae tendinae with severe, eccentric regurgitation directed towards the right upper pulmonary vein. The pulmonary capillary wedge pressure (PCWP) in the right upper lobe exceeded the PCWP of the left lung by 20 mm Hg.

We have described a rare case of unilateral pulmonary oedema, restricted to the right upper lung lobe (also termed quadrant pulmonary oedema), which was caused by acute, eccentric mitral regurgitation towards the right upper pulmonary vein. After mitral valve repair the chest x ray was normal.

Standard chest x ray with a right upper lobe infiltrate (white arrow). Transoesophageal echocardiography still frame: mitral valve regurgitant jet directed towards the right upper pulmonary vein (red arrow). LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. Left PCWP tracing with v wave of 40 mm Hg (right upper corner) versus v wave of 60 mm Hg in the right PCWP tracing (left upper corner).