Paradoxic air embolism in the absence of an intracardiac defect. A 58-year-old man experienced paradoxic air embolism with passage of air from the systemic venous to the systemic arterial circulation with subsequent stroke and death. No intracardiac shunt was present. Pulmonary fibrosis concomitant with severe pulmonary arterial hypertension appears to have been responsible for the air traversing the pulmonary capillary bed. This unusual outcome of a complicated central venous catheterization must be borne in mind and guarded against in similar patients. 