Profiles of instant heart rate during partial seizures.

Instant heart rate (R-R intervals) can be readily studied during spontaneous seizures recorded with ambulatory cassette AEEG/AECG techniques. Ninety-three seizures were recorded in 32 patients with complex partial epilepsy. Instant R-R interval plots showed that 74% of seizures were associated with a dominant tachycardia, the most characteristic features of which were the initial steep acceleration phase at seizure onset and the wide fluctuations in heart rate ('exaggerated sinus arrhythmia') which occurred during and immediately after the seizure. Five percent of seizures were associated with a dominant but transient phase of heart rate slowing during or towards the end of the seizure. Nineteen percent of seizures showed equivocal or negative ictal effects on the heart rate and rhythm despite unequivocal AEEG seizure discharges. Conversely, other patients had characteristic heart rate changes despite equivocal AEEG abnormality. The heart rate profiles showed striking seizure-to-seizure similarities when multiple fits were recorded in the same patient. Ratemeter profiles may be clinically useful to locate epileptic seizures in long duration records; they can help to locate seizures which are either inaccurately timed or poorly identified by the event marker, or not clearly associated with definite AEEG changes. The secondary cardiac effects of epilepsy may be misdiagnosed if their primary cerebral origin is not suspected.