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Summary:Purpose: To determine the prevalence of heart rate changes and ECG abnormalities during epileptic seizures and to determine the timing of heart rate changes compared to the first electrographic and clinical signs. To assess the risk factors for the occurrence of ECG abnormalities.Methods: We analyzed retrospectively 281 seizures in 81 patients with intractable epilepsy who had prolonged video-EEG and two-channel ECG. The nature and timing of heart rate changes compared to the electrographic and clinical seizure onset was determined. The ictal period (including one minute preictally and three minutes postictally) was analyzed for cardiac arrhythmias, conduction and repolarization abnormalities. Risk factors for cardiac abnormalities were investigated using parametric and non-parametric statistics.Results: There was an increase in heart rate of at least 10 beats/minute in 73% of seizures (93% of patients) and this occurred most often around seizure onset. In 23% of seizures (49% of patients) the rate increase preceded both the electrographic and the clinical onset. ECG abnormalities were found in 26% of seizures (44% of patients). One patient had an asystole for 30 seconds. Long seizure duration increased the occurrence of ECG abnormalities. No other risk factor was found.Conclusions: Heart rate changes occur frequently and occur around the time or even before the earliest electrographic or clinical change. The change can clarify the timing of seizure onset and the specific rate pattern may be useful for seizure diagnosis and for automatic seizure detection. ECG abnormalities occur often and repeatedly in several seizures of the same patient. Key Words: Heart rate-ECG-Epilepsy-Seizure onset-Asystole.Heart rate changes at the onset of epileptic seizures are often overlooked as a clinical sign. An increase in heart rate has been described in a high proportion of seizures (1-7) and the timing of these changes may provide useful clinical information. The purpose of our study is to describe the timing of changes in heart rate compared to the electrographic and clinical seizure onset. Although heart rate changes have often been described in seizures, the specific timing of these changes has not been reported. If the increase is at the onset or even before a seizure, it could be a helpful additional clinical sign in determining seizure onset. The prevalence of heart rate changes and their timing might also suggest uses for ECG detectors in the effort to detect seizures automatically.While most studies have noted increases in heart rate around some seizures, there are also instances of decreased heart rate, and an increased occurrence of serious ECG abnormalities (1,2,8). Sudden unexpected death in epilepsy (SUDEP) is a major cause of death in patients with epilepsy, especially in patients with intractable epilepsy (9,10) and SUDEP occurs much more when patients are having seizures (11). Cardiac and respiratory changes could possibly contribute to SUDEP (12) and it is known that ECG abnormalities occur often durin...

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