The single most important indication for emergency pulmonary embolectomy is:

C. The presence of persistent and intractable hypotension.

DISCUSSION: The likelihood of another episode of pulmonary embolism is not an indication for pulmonary embolectomy since recurrent embolism may also be managed nonoperatively in most cases. Myocardial infarction should definitely be ruled out before pulmonary embolectomy is considered. In the presence of intractable cardiopulmonary collapse the only measure apt to correct the condition is emergency pulmonary embolectomy employing extracorporeal circulation. In such instances emboli generally are massive, with more than 50% of the pulmonary arterial circuit being occluded. The presence of cardiac and/or respiratory insufficiency before the attack of embolism is important, as that is apt to mean that a smaller pulmonary embolism is present that can cause serious cardiovascular changes.