Effects of seizures on cardiac function.

Various chronic and acute autonomic effects on the heart are seen during epileptic seizures, and some have been implicated in cases of sudden unexpected death in epilepsy (SUDEP). Chronic autonomic dysfunction, either congenital or acquired through seizures or medications, and structural changes of the heart may all predispose patients to SUDEP. Acute autonomic changes during seizures, in particular ictal bradycardia or transient ischemia, may indicate an increased and preventable risk of mortality in patients with epilepsy. However, there is no definite epidemiologic evidence associating any of the chronic or acute cardiac effects of seizures with SUDEP. Cases of SUDEP and near-SUDEP recorded during long-term electroencephalography monitoring offer some insight into the potential mechanisms leading to SUDEP. These cases suggest that autonomic instability ending in cardiorespiratory arrest may be provoked by postictal suppression rather than by ictal activation of the autonomic nervous system. Additional epidemiologic studies on high-risk populations and access to recorded cases of SUDEP may provide more details about the exact sequence of events leading to death and thus guide the development of possible preventive strategies.