A 22 year old man was admitted to the accident and emergency department having sustained a 5 × 3 cm knife wound to the right anterior chest wall in the fourth intercostal space. He was haemodynamically stable on admission but dyspnoeic at rest. Pulse was 110 beats/min and blood pressure 106/60 mm Hg. The only abnormality on examination was dullness to percussion on the right chest wall; heart sounds were normal. A plain chest x ray confirmed a right haemothorax. Three litres of blood were drained using an intercostal drain. A median sternotomy was performed; the right internal thoracic artery, which had been transected, was ligated. A small laceration in …