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Terminal electrocardiographic changes in brain-dead patients
Neurology
|June 1, 1985
Summary
Brain death disrupts normal heart rhythms, leading to a slowing atrial mechanism and junctional escape rhythms, but not ventricular escape rhythms. Prolonged QT intervals may precede terminal ventricular tachycardia.
Area of Science:
- Cardiology
- Neurology
- Forensic Medicine
Background:
- Electrocardiography (ECG) is crucial for assessing cardiac function.
- Understanding terminal cardiac electrical activity in brain death is vital for clinical and legal contexts.
- Previous studies have described various terminal rhythms, but a comprehensive analysis in brain-dead patients is limited.
Purpose of the Study:
- To analyze electrocardiographic (ECG) changes from ventilation cessation to cardiac asystole in brain-dead patients.
- To identify patterns of atrial, junctional, and ventricular electrical activity during the dying process.
- To investigate the relationship between QT interval, J waves, and terminal rhythms, including ventricular tachycardia.
Main Methods:
- Analysis of ECG recordings from 18 brain-dead patients.
- Monitoring initiated at the termination of mechanical ventilation until the cessation of all electrocardiographic activity.
- Correlation of observed ECG findings with patient temperature (hypothermic vs. euthermic).
Main Results:
- A progressive slowing of the atrial mechanism was observed, followed by atrioventricular (AV) block or a slowing junctional escape rhythm.
- No instances of a ventricular escape rhythm were recorded despite the failure of atrial and junctional pacemakers.
- Three terminal rhythms were identified: atrial activity only, slow junctional rhythm/sinus bradycardia, and ventricular tachycardia (VT).
- A prolonged corrected QT interval was associated with the later development of VT.
- J waves were present in one hypothermic and three euthermic patients.
Conclusions:
- Cardiac electrical activity in brain death follows a predictable pattern of progressive failure from atrial to junctional pacemakers.
- Ventricular escape rhythms do not occur in brain death, differentiating it from other forms of cardiac arrest.
- Terminal ventricular tachycardia can occur, and its development is potentially predicted by a prolonged QT interval.