Myocardial infarction is generally very sudden and does not infarct slowly. Infarction refers to the sudden blockage of blood, including the following situations: 1, violent contraction of blood vessels spasm: spasm case, the most serious state is the complete occlusion of blood vessels, blood vessels muscle next to each other occlusion, before doing interventional treatment, giving nitroglycerin blood vessels can be completely restored to normal. Severe spasm can occur in a large number of smoking, cold wind blowing stimulation, spastic body and other cases; 2, vascular plaque rupture: human blood vessels are good at birth, middle-aged and young people began to plaque gradually grow, with age increase plaque will be more and more, more common in the case of high blood lipids, endothelial insufficiency. The plaque is getting bigger and bigger, like a volcano, which will top the endothelium very thinly. If the endothelium is incompetent, and then encounter the change of blood pressure and increase of oxygen consumption, including strenuous exercise, cold wind stimulation, smoking, etc., the plaque endothelium may rupture. When the plaque is exposed, a blood clot will grow and repair the endothelium like a long blood crust, which can block the lumen and cause ischemic necrosis of the myocardium.