With the application of cardiopulmonary bypass, therapy of massive pulmonary embolism has entered a new phase.1,2 A recent historical review, by Hume in the October issue of the Archives of Surgery,3 indicates how areas of research are contributing to the current successful management of pulmonary embolectomy, which was a rarity not long ago. Priming the circuit without blood4 makes cardiopulmonary bypass available on short notice. Disposable circuitry and oxygenators may be prepackaged, sterilized, and kept ready in the same way as has been done with surgical instruments for thoracotomy. Once the patient is on partial or complete cardiopulmonary bypass, embolectomy becomes a rather straight-forward maneuver. Before the patient is on bypass, however, potential delays are a source of concern. Most patients do not succumb instantly to massive pulmonary embolus. Many survive for several hours, which suggests that enough time is available for definitive treatment to be instituted.