Electrocardiographic findings in brain death; description and presumed mechanism.

Electrocardiogram changes and pharmacologic responses were studied in 28 cases of brain death. Cardiac activity in this condition is possibly determined by the dynamic balance between the depressant action of hypothermia and the stimulating action of the sympathetic nervous system (without any vagal or central influence). The electrocardiographic alterations are the results of this dual influence, and are probably characteristic of this condition. In the initial stage of brain death the ECG shows J waves in the terminal part of the QRS, prolongation of the QT interval and the ST-T changes; in the advanced stages, progressive showing of the heart rate and the depolarization and repolarization processes are observed (manifested by gradual accentuation of the findings mentioned above); in the terminal stage dynamic electrocardiographic changes (among them, progressive depression of sinus activity, atrial fibrillation, atrioventricular and intraventricular conduction disturbances and severe ST-T changes) appear. It is possible that additional factors, like metabolic changes and possible myocardial damage in some instances, may have some influence on the electrocardiographic pattern. Final conclusions cannot be drawn from these preliminary observations. The atropine test was found to be an efficient and simple diagnostic aid in cases of brain death.