Floating pulmonary embolus: unusual cause of recurrent syncope.

A 69-year old woman was admitted because of recurrent syncopal episodes. In hospital, she had repeated attacks of near fainting or syncope when she was turned into the left decubitus position. Continuous arterial pressure monitoring revealed that severe hypotension initiated these events. Secondarily, the heart rate dropped markedly. The symptoms quickly reversed when the patient was turned back into the supine or right decubitus position. Angiography revealed a large, riding and partly floating pulmonary embolus that obstructed the pulmonary circulation to a variable degree, apparently influenced by the patient's body position. During subsequent emergency surgery the angiographic findings were confirmed. It appears that the severe hypotensive episodes were caused by intermittent high degree obstruction of the pulmonary circulation by the floating pulmonary embolus, a mechanism that, to our knowledge, has not previously been described as a cause of recurrent syncope.