Trepopnea due to interatrial shunt following lung resection.

Dyspnea and platypnea following pneumonectomy have been reported as a result of right-to-left interatrial shunt. We report on a case of trepopnea with marked positional arterial oxygen desaturation following right middle and lower lobectomy. A similar mechanism was found, with right-to-left interatrial shunting occurring predominantly in the right lateral position. Surgical repair corrected the clinical and physiologic abnormalities.