A seizure is a temporary event caused by abnormal, excessive electrical activity in the brain. This “electrical storm” often raises concern that the body’s other vital functions, particularly the heartbeat, might falter or stop. While the brain’s electrical activity does influence the heart, the direct answer is that the heart generally does not stop. The connection between the two systems, however, is complex and worth exploring.
The Typical Cardiac Response During a Seizure
The heart does not cease beating during a seizure; instead, it usually experiences a transient change in rate and rhythm. The most common cardiac event is a rapid increase in heart rate, known as ictal tachycardia. This acceleration is observed in 50% to 100% of monitored seizures.
Heart rates often range from 100 to 120 beats per minute, sometimes exceeding 170 beats per minute. Less frequently, a temporary slowing of the heart rate, or bradycardia, may occur during or immediately after the seizure. These fluctuations are usually brief and self-correcting, with the heart returning to its normal rhythm without intervention once the seizure ends.
The Brain-Heart Connection: Autonomic System Involvement
The mechanism behind these heart rate changes is the link between the brain and the body’s involuntary functions, mediated by the Autonomic Nervous System (ANS). The ANS is the body’s automatic regulator, controlling heart rate, breathing, and digestion outside of conscious control. It has two opposing branches: the sympathetic system, which accelerates the heart (the “fight or flight” response), and the parasympathetic system, which slows it down (the “rest and digest” response).
The intense electrical discharge of a seizure can disrupt these regulatory signals. Seizures spreading to central autonomic centers in the brain, such as the insula and amygdala, are most likely to cause cardiovascular changes. Activity affecting the right insular cortex tends to stimulate the sympathetic system, resulting in tachycardia. Conversely, involvement of the left hemisphere can promote parasympathetic activity, which may lead to bradycardia.
Defining Severe Cardiac Risks and Sudden Death
While temporary rate changes are common, seizures can rarely induce severe cardiac events that carry serious risk. Ictal asystole is an infrequent condition where the heart temporarily stops beating entirely, often lasting for a few seconds. This severe slowing or stopping is most often linked to focal seizures.
The most serious health implication associated with epilepsy is Sudden Unexpected Death in Epilepsy (SUDEP). SUDEP is the leading cause of premature death in people with uncontrolled seizures. It is defined as the sudden, non-traumatic, and non-drowning death of a person with epilepsy where no other cause is found after a post-mortem examination. The cause of SUDEP is hypothesized to involve a combination of factors.
SUDEP frequently results from a cascade involving severe breathing problems followed by cardiac failure. A seizure, particularly a generalized tonic-clonic seizure, can cause a prolonged pause in breathing, or apnea, dramatically lowering blood oxygen levels. This lack of oxygen, combined with abnormal heart rhythms, can suppress brainstem function, leading to a fatal cardiorespiratory collapse. Recurrent seizures may also cause chronic functional and structural heart changes, sometimes described as the “epileptic heart,” which can predispose a person to dangerous arrhythmias.
Monitoring and Managing Cardiac Risk in Epilepsy
The primary strategy for mitigating cardiac risk in epilepsy is achieving the best possible seizure control, as seizure frequency is the biggest risk factor for SUDEP. Adherence to anti-seizure medications (ASMs) as prescribed is the most effective way to reduce this risk. However, some ASMs, particularly those affecting sodium channels, carry arrhythmogenic risks, necessitating careful monitoring.
Specialized cardiac monitoring is often employed for individuals who experience fainting or collapsing during a seizure, or those with drug-resistant epilepsy. Tools like routine electrocardiograms (EKGs), Holter monitors, or long-term subcutaneous cardiac monitors help identify underlying heart issues or seizure-related arrhythmias like ictal asystole. In rare cases of recurrent, severe seizure-induced bradycardia or asystole that do not respond to seizure control, a cardiac pacemaker may be considered to prevent falls and loss of consciousness. Cardiovascular risk guidelines and regular assessment of cardiac markers are recommended to reduce the chances of premature cardiac death.