β adrenergic blockade prevents cardiac dysfunction following status epilepticus in rats

Status epilepticus (SE) can result in temporary cardiac dysfunction in patients, characterized by reduced ejection fraction, decreased ventricular contractility, and alterations in electrical activity of the heart. Although reversible, the cardiac effects of seizures are acutely life threatening, and may contribute to the delayed mortality following SE. The precise mechanisms mediating acute cardiac dysfunctions are not known. These studies evaluated effects of self-sustaining limbic SE in rats on cardiac performance 24h following seizures, and determined if sympathetic nervous system activation during seizures contributed to cardiac dysfunction. Rats subjected to SE received either vehicle (saline) or the B1 adrenergic antagonist atenolol (AT) prior to and during 90 min of seizure activity. Control rats were similarly treated, except they did not undergo seizures. Twenty-four hours after SE, animals were anesthetized and catheterized for measurement of cardiac performance variables. Animals undergoing SE demonstrated significantly reduced cardiac output, decreased ventricular contractility and relaxation, increased blood pressure, and prolonged QT interval. However, heart rate was not altered. Treatment with AT prevented all changes in cardiac performance due to SE, and attenuated the increase in QT interval. These data demonstrate that SE in the rat results in cardiac dysfunction 24h following seizures, mediated by the sympathetic nervous system.