中等大小血栓引起的肺动脉栓塞导致的大面积梗死，梗死灶周围先发生机化。当然也有可能有多个小血栓，但不引起猝死，因为没有堵塞大的肺动脉分支，也就不引起梗死。然而,如果存在大量小血栓，尤其是同时进入肺组织，就会共同堵塞很多小动脉，引起肺高血压。
Here is a larger area of infarction produced by a medium-sized thromboembolus to the lung. This infarction has begun to organize at the margins.It is also possible to have multiple small pulmonary thromboemboli that do not cause sudden death and do not occlude a large enough branch of pulmonary artery to cause infarction. However, if there are lots of small emboli, particularly if they are showered to the lungs over a period of time, then they collectively may block enough small arteries to produce pulmonary hypertension.
