A 49 year old man presented through accident and emergency with an acute confusional state and a five day history of being non-specifically unwell. On examination he was found to be pyrexial (38.4 °C) and there was systolic murmur. Magnetic resonance imaging (MRI) of the brain was suggestive of meningoencephalitis and it was treated accordingly. Blood cultures revealed growth of Staphylococcus aureus and echocardiography studies were requested to rule out infective endocarditis. Transthoracic echocardiography demonstrated a structure arising from the non-coronary cusp of the aortic valve. It was protruding into the left ventricular outflow tract. Interestingly, there was evidence of blood flow inside the structure, proving that it was not a solid lesion and suggesting that it may well be a localised aneurysmal formation. The patient underwent transoesophageal echocardiography in order to clarify anatomy of the abnormality. It clearly demonstrated flow into the structure and into the left ventricular outflow tract (panels A–C), confirming a localised aneurysmal or sac-like nature of it. MRI failed to provide additional information. The patient became asymptomatic within a few days of antibiotic treatment with rapid normalisation of inflammatory markers. The patient was discharged home with advice regarding antibiotic prophylaxis for infective endocarditis. We concluded that the structure was most likely a congenital abnormality. To date we have found no reports in the literature of a similar abnormality in a tricuspid aortic valve. A case has been reported of aneurysmal formation of a bicuspid aortic valve (

).