A 54 year old woman was admitted with a history of central chest pain. She was a smoker and had a family history of ischaemic heart disease. Examination was unremarkable and her resting ECG revealed sinus rhythm with no acute changes. Her cardiac troponin T was negative and she had a standard Bruce protocol exercise tolerance test, which was equivocal. She subsequently underwent coronary angiography, which revealed a normal dominant right coronary artery and mild disease in the left coronary system with an interesting finding of drainage of blood from the left coronary system directly into the left ventricular cavity (panels A and B). This pattern of cardiac drainage is similar to reptilian cardiac physiology in which transmural channels enable dual blood supply to the myocardium.
