Coronary stenosis treatment. Coloured angiogram of a balloon catheter (white tube, centre right) inserted into the anterior interventricular branch of the left coronary artery in the heart of a 60-year-old patient affected by severe stenosis (narrowing). This condition was the cause of a myocardial infarction (heart attack). The balloon catheter is inflated for a predetermined amount of time to stretch and enlarge the narrowed (stenosed) section of the artery, thus improving blood flow.