Unilateral absence of right-lung perfusion with normal ventilation on radionuclide lung scan as a sign of aortic dissection.

A case of aortic dissection with unilateral absence of right-lung perfusion and normal ventilation on radionuclide ventilation/perfusion (V/Q) lung scan is presented with a review of the literature. Anticoagulation or thrombolytic therapy for presumed pulmonary embolism may be catastrophic if the clinical syndrome and V/Q scan appearance are instead due to aortic dissection. With this V/Q scan appearance, these therapies should not be instituted unless pulmonary embolism is diagnosed by pulmonary arteriography.