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.

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