Light micrograph of a section through a human coronary artery showing the almost total obstruction of the interior (lumen) by the development of a haemorrhage (bright red) into an atheromatous plaque (pink). The atheroma plaque alone obstructs about half of the interior. Such localised haemorrage occurs through rupture of small capillaries that permeate an established atheroma plaque. Although the degree of bleeding is trivial, the consequences in an already obstructed artery may be disastrous. Here, the obstruction resulted in the cessation of blood supply to the left ventricle leading to acute myocardial infarction - a heart attack. UFig. 7.5 Basic Histopathology U