Wedged Swan-Ganz catheter causing ventilation-perfusion mismatch. Case report and review of the literature.

A ventilation-perfusion (V/Q) lung scan in a postoperative patient with a Swan-Ganz catheter showed an area of mismatch suggesting pulmonary embolism. Radiographs, as well as failure to get a venous return from the catheter suggested wedging. A pulmonary angiogram, performed after the Swan-Ganz catheter was pulled back, was essentially normal. An autopsy performed within 24 hours of the lung scan did not reveal pulmonary emboli. Wedged Swan-Ganz catheter was probably responsible for the V/Q mismatch.