The electrocardiographic changes in pneumothorax in which the heart has been rotated: The similarity of some of these changes to those indicating myocardial involvement

The electrocardiograms of seven cases of pneumothorax, five spontaneous and two artificial, are described. In three, and possibly in six of the cases, the changes were significant enough to suggest the presence of myocardial involvement, and yet three of these definitely had good heart muscle. A prominent S-wave in Lead I was present seven times—in 100 per cent of the cases; a right axis deviation of the QRS group occurred in five cases, small amplitude of the QRS group four times, and small T-waves three times. Unusually high or low voltage of the S-T segments was present three times; finally, tachycardia was noted three times. All of the right pneumothorax cases showed a right axis deviation of the QRS group.In pneumothorax, particularly right pneumothorax, a rotation of the heart occurs and probably accounts for the findings described. Another way of stating the same fact might be to say that the right ventricle comes closer to the frontal leads than ordinarily.Follow-up procedures on two patients, whose pneumothorax had disappeared, showed a return to a normal electrocardiogram, with a disappearance of the characteristic changes observed in pneumothorax.The most marked electrocardiographic changes occurred with displacement of the mediastinum.It is suggested that the S-T changes noted in acute coronary closures. i.e., the high take-off of the S-T transition period from the QRS group may be due, at least in a measure, to a rotation of the heart which may occur when a portion of the heart muscle dies.The low voltage of the QRS group and the T-waves is probably to be accounted for either by the rotation of the heart or by the fact that air in the chest is a poor conductor for the heart current.