A seizure is a temporary disruption of the brain’s normal electrical activity, caused by sudden, excessive, and synchronized firing of nerve cells. This neurological event can manifest in various ways, from subtle changes in awareness to full-body convulsions. While most seizures pass without severe long-term complications, there is a known, though rare, connection between seizures and life-threatening cardiac events, including cardiac arrest. This link stems from the brain’s ability to influence the heart’s rhythm and function, which requires an explanation of the specific mechanisms and risks involved.
Understanding Sudden Unexpected Death in Epilepsy (SUDEP)
The most concerning context for seizure-related cardiac arrest is Sudden Unexpected Death in Epilepsy (SUDEP). SUDEP is defined as the sudden, unexpected, non-traumatic, and non-drowning death of a person with epilepsy when a postmortem examination reveals no other cause. It is the leading cause of epilepsy-related mortality, though it remains a rare event overall.
Experts estimate that SUDEP affects approximately one in every 1,000 adults with epilepsy each year. The exact cause is not fully understood, but it results from a combination of respiratory problems, brain function changes, and fatal heart rhythm disturbances triggered by a seizure. This event is often unwitnessed and frequently occurs during sleep. Maintaining optimal seizure control is important due to the seriousness of this risk.
How Seizures Disrupt Cardiac Rhythm
The physiological connection between a seizure and a cardiac event centers on the Autonomic Nervous System (ANS). The ANS controls involuntary functions like heart rate and breathing. Seizure activity, especially when it spreads to brain regions like the temporal lobe, can overwhelm the ANS with an abnormal surge of signals. This surge leads to sudden dysfunction in the heart’s electrical system.
This disruption often results in a dangerous cardiac arrhythmia. Tachycardia (increased heart rate) is the most common change observed during a seizure, but life-threatening events involve dramatic slowing. These include severe bradycardia (a dangerously slow heart rate) or ictal asystole (a complete, though often transient, cessation of the heartbeat). The autonomic imbalance can also precipitate chaotic rhythms like ventricular fibrillation, which prevents the heart from effectively pumping blood and results in cardiac arrest.
Factors That Increase Cardiac Risk
The risk of a seizure triggering a severe cardiac event is significantly higher in those with specific disease characteristics. Generalized Tonic-Clonic Seizures (GTCS), often called grand mal seizures, are the type most strongly associated with cardiac risk and SUDEP. These convulsive seizures cause the most profound disruptions to breathing and heart function.
Seizure frequency is another major factor, as the risk of SUDEP increases substantially when seizures are uncontrolled. Patients who experience three or more GTCS events per year are considered higher risk. Many events, particularly those leading to SUDEP, occur during sleep, making timing a significant consideration. Consistent adherence to prescribed anti-seizure medication is a protective measure, as it reduces the frequency of the most dangerous seizure type.
Strategies for Risk Reduction
The primary way to mitigate cardiac risk is to achieve the best possible seizure control. This involves working closely with a neurologist to ensure the medication regimen is optimal and taking anti-seizure medications exactly as prescribed. Reducing the number of Generalized Tonic-Clonic Seizures is the most effective preventative strategy.
For individuals with high-risk factors, such as frequent nocturnal seizures, seizure detection and monitoring devices are important. These devices, which include specialized watches or under-mattress sensors, alert caregivers to a potential convulsive seizure, allowing for timely intervention. Open communication with both neurologists and cardiologists about cardiac symptoms, such as unexplained palpitations or fainting, ensures a comprehensive approach to managing the overall risk.