P412Effect of post-infarction changes of heart on autoregulation of cerebral circulation and manifestation of seizure activity

Abstract

Purpose: To study the specifics of changes in autoregulation of cerebral hemodynamic in different periods past the myocardial infarction and its connection to seizure activity. Methods: The tests were performed on white male Wistar rats. Myocardial infarction (IM) was modeled by ligation of left coronary artery. Record of video ECG-EEG was performed in on line mode using telemetry system by ADInstruments (Australia). Transmitter (TR40BB) was implanted in the abdominal cavity of the rat. Ultrasound study controlled cardiac output, volumetric blood flow in common carotid artery, linear blood flow (LBF) in basilar artery. Autoregulation of cerebral hemodynamic was performed using hypercapnic and compression functional test. Seizure activity of the animals was detected using the EEG changes in rhythmic photostimulation. Magnetic resonance tomography was performed using Bruker Biospec 70/30. Results: Transcranial Doppler sonography failed to detect changes in LBF in basilar artery and volumetric blood flow in common carotid artery in acutest (2 days), acute (2 weeks) and sub-acute (2 months) periods after IM, signifying the lack of disorder in cerebral circulation. However during acutest and acute period reaction of basilar artery to hypercapnic and compression test differed. Part of animals showed increased seizure activity in this period, with increased seizure activity in acutest period accompanied by decreased reactivity of metabolic and myogenic autoregulation cascades, while the animals without seizure activity only displayed the decreased reactivity of basilar artery in hypercapnic test. In acute period both animals with seizure activity and without it only displayed the decrease in metabolic autoregulation cascade. Thus despite the absence of cerebral circulation disorder in acutest and acute periods of IM part of animals displayed increased seizure activity. In sub-acute period there were no changes in cerebral autoregulation and seizure activity in animals. Conclusion: Non-effective operation of heart in post-infarction period differently affects potential capacity of cerebral autoregulation and degree of seizure activity of the brain. Lack of violation of cerebral circulation allows us to exclude the decrease of oxygen supply to the brain. Thus the increased seizure activity with adequate brain circulation is most likely caused not by hypoxia but by neurovegetative dysbalance, manifesting earlier than cerebral hemodynamic disorder.