Remember that New Electrocardiogram Changes in a Patient with a Subarachnoid Bleed may be a Sign of Progression of the Bleed
Amisha Barochia MD
Loss of consciousness is a common clinical occurrence in subarachnoid hemorrhage. However, the sudden death seen in these patients is thought to be the result of cardiac rhythm disturbances. Although the exact pathophysiology is unknown, there appears to be an imbalance in the autonomic nervous system, which leads to a catecholamine surge, changes in repolarization and depolarization, and subsequent ectopic foci. Hypokalemia secondary to increased circulating catecholamines, vomiting, and hypercortisolism may also contribute to the development of arrhythmias associated with a subarachnoid bleed.
Watch Out For
The most frequently observed electrocardiogram (ECG) changes in patients with subarachnoid bleeds include T wave inversions, ST-segment elevations or depressions, Q waves, U waves ≥0.1 mV, and QT prolongation. ECG changes secondary to subarachnoid bleeds may even mimic the changes seen in acutemyocardial infarction. However, even though these latter changes may be associated with abnormal thallium perfusion scans in up to one-third of patients, they are not generally indicative of underlying myocardial ischemia. When autopsy specimens from patients with these ECG changes are examined, there is no correlation with the presence of coronary artery disease and the myocardium is intact on microscopic examination. ECG changes usually associated with a poor prognosis include pathologic Q waves, raised ST segments, P mitrale, QT prolongation ≥450 milliseconds, and tachycardia. However, one recent study did not find a relationship between the type or location of ECG change and mortality.
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