Absence of pulsus paradoxus in a patient with cardiac tamponade and coexisting pulmonary artery obstruction.

Pulsus paradoxus is a key physical finding in patients with cardiac tamponade. This report describes a 38-year-old woman with metastatic adenocarcinoma who had cardiac tamponade confirmed by cardiac catheterization. Pulsus paradoxus was notably absent. No evidence could be found for an atrial septal defect, significant aortic regurgitation, elevated left ventricular diastolic pressure, or localized tamponade, previously described disorders in which pulsus paradoxus may not be seen when tamponade occurs. The lack of pulsus paradoxus in this case was attributed to right ventricular pressure overload due to mechanical obstruction of the pulmonary artery.