Potassium2026-07

Altered autonomic balance drives the increase in cardiac output and arterial pressure during convulsive seizures in nonanesthetized sheep.

Pustovit Ruslan V, Lankadeva Yugeesh R, Booth Lindsea C, Hood Sally G et al. — Epilepsia

Summary

This study in sheep investigated how convulsive seizures affect the heart and blood pressure. Researchers found that seizures significantly increase blood pressure and the heart's pumping action, driven by changes in the nervous system. Notably, seizures also led to a temporary drop in blood potassium levels, which is crucial for proper heart function.

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Key points

Convulsive seizures can significantly increase blood pressure and the amount of blood the heart pumps.
These cardiovascular changes are linked to shifts in the body's automatic nervous system activity.
Seizures were also observed to cause a temporary decrease in blood potassium levels.
Such changes might contribute to heart-related risks following seizures.

What the study looked at

**What question the study asked:** This research aimed to understand how convulsive seizures impact the heart and blood circulation, specifically investigating the role of the body's automatic nervous system in these changes. Scientists were also interested in whether seizures affect important blood components. **How it was studied:** The study involved adult female sheep that were not under anesthesia. Researchers induced seizures using a specific medication and continuously monitored various vital signs, including blood pressure, heart rate, and brain activity. They also measured the heart's pumping ability, nervous system signals to the heart and kidneys, and collected blood samples to check for biochemical changes. **What it found:** The study revealed that convulsive seizures led to a substantial and prolonged increase in both blood pressure and the heart's output. These effects were accompanied by significant alterations in the automatic nervous system's control over the heart and other organs. Importantly, the researchers observed a temporary but significant decrease in blood potassium levels during and after seizures, alongside an increase in lactate. These findings suggest that seizures can cause widespread disturbances in the body's systems, potentially increasing cardiovascular risks.

Dietary takeaway

This study highlights that convulsive seizures can temporarily reduce blood potassium levels, which is vital for maintaining a healthy heart rhythm and overall cardiovascular function. While this research was conducted in sheep and doesn't directly recommend dietary changes for humans, ensuring adequate potassium intake through a balanced diet rich in fruits, vegetables, and legumes is generally beneficial for heart health. Remember, this is just one study, and more research is needed to fully understand the implications for human dietary recommendations.

Abstract

OBJECTIVE: Preclinical and human studies suggest that ictal and interictal modulation of the sympathetic and parasympathetic systems contributes to cardiovascular changes that may induce sudden unexpected death in epilepsy. We therefore investigated the effects of convulsive seizures on cardiovascular and autonomic function in nonanesthetized sheep. METHODS: Adult female sheep were instrumented to record arterial pressure, heart rate, electroencephalogram, electrocardiogram, and either cardiac output or cardiac and renal sympathetic nerve activity (SNA). Arterial blood samples were collected to assess blood biochemistry. Seizures were induced in nonanesthetized sheep by intravenous infusion of the proconvulsant pentylenetetrazol (PTZ; 5.0 mg/kg/min for 4 min). RESULTS: PTZ induced consistent generalized tonic-clonic seizures associated with abnormal activity on electroencephalogram. Convulsive seizures increased mean arterial pressure (79.1 ± 4.5 mmHg to 128.5 ± 5.6 mmHg, p < .0001) and cardiac output (4.1 ± .2 to 7.9 ± .5 L/min, p < .0001) at 10 min postseizure; these remained significantly above baseline for 60 min (both n = 12). Heart rate variability decreased (4826.1 ± 766.6 to 210.9 ± 97.7 ms, n = 6, p = .0155) at 10 min and corrected QT interval increased (399 ± 9.1 to 449.7 ± 11 ms, p = .003) at 30 min postictally. Seizures increased cardiac SNA (682 ± 86 to 7558 ± 3955 spikes/min, n = 4, p = .007), whereas renal SNA decreased (4296 ± 784 to 1139 ± 284 spikes/min (p = .047). Seizures decreased blood potassium (3.9 ± .1 to 3.4 ± .1 mmol·L, p = .0268) and increased lactate (.68 ± .05 to 12.2 ± 1.39 mmol·L; p < .0001). SIGNIFICANCE: Seizures induced by PTZ in nonanesthetized sheep caused autonomic and cardiovascular disturbances, including postictal tachycardia and arrhythmias, which may contribute to an increased risk of sudden unexpected death in epilepsy.

View on PubMed →DOI: 10.1002/epi.70358