Unusual electrocardiographic changes in intrathoracic conditions.

Electrocardiographic, roentgenographic and clinical findings from 5 patients with intrathoracic conditions were studied. Three patients suffering from left spontaneous pneumothorax and one from eventration of the left diaphragm were found to have an unusual phasic voltage alternation in their electrocardiograms. These changes were appearing during the course of the disease and disappearing with the correction of the condition. Respiratory variation of intrathoracic anatomy or amplitude and swinging of the heart seems a possible explanation.