The pathological basis and microanatomy of occlusive thrombus formation in human coronary arteries.

Myocardial necrosis, usually called infarction, occurs in different patterns. A common form is necrosis of one segment of the left ventricle, i.e., anterior, septal, lateral or posterior. This regional infarction is consistently associated with an acute occlusive thrombosis of the artery supply that region. Diffuse necrosis involving the whole circumference, usually the subendocardial zone, of the ventricle is not consistently associated with thrombi. Occlusive thrombi identified in post-mortem coronary arterio-grams have been reconstructed in their entirety from serial sections at 150 micron intervals. Most occlusive thrombi were found to be associated with a dissection track into the intima at an atheromatous plaque. The break into the plaque usually extended over several millimeters, often in spirals, so that a mass of thrombus within the plaque compressed the original lumen. Previous accounts of plaque rupture or cracking greatly underestimated the magnitude of the dissection of blood into the intima.