It occurs because blood flow gets reduced in that blood vessel and so the heart muscle, which is actively beating all the time, needs large quantities of oxygen provided by blood can't get the blood through the vessel.

发病原因是冠状动脉血流量降低,因为心肌搏动永不停歇,随时需要血液供给大量氧气,发病时血液无法正常流过血管

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