Tohoku J. Exp. Med., 2012, 226(1)

Brain Responses to Cardiac Electrical Stimulation: A New EEG Method for Evaluating Cardiac Sensation

HIDEAKI SUZUKI,¹ MASANORI HIROSE,¹ SATOSHI WATANABE,² KOJI FUKUDA,¹ SHIN FUKUDO² and HIROAKI SHIMOKAWA¹

¹Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
²Department of Behavioral Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan

Although cardiac sensation, such as palpitation or chest pain, is common and is sometimes a malignant sign of heart diseases, the mechanism by which the human brain responds to afferent signals from the heart remains unclear. In this study, we investigated whether electrical stimulation of the heart provokes brain responses in humans. We examined 15 patients (age: 65.4 ± 3.1 years old, 11 males and 4 females) implanted with either a cardiac pacemaker or cardiac resynchronization therapy (CRT) device. Electroencephalogram (EEG) was simultaneously recorded from the vertex during right ventricular pacing at 70-100 beats/min at baseline (1.5 V) and intense (6-8 V) stimulation sessions. We evaluated brain responses to cardiac electrical stimulation by measuring cerebral potentials that were obtained by subtracting the average of 100 EEG waves triggered by cardiac pacing during baseline stimulation from those during the intense stimulation. Intense stimulation of the cardiac pacemaker or CRT device reproducibly induced cardiac sensation in 6 out of the 15 patients; namely, the remaining 9 patients showed no reproducible response. Brain responses were evident by averaging cerebral potentials from all of the 15 patients and those from 6 patients with reproducible cardiac sensation. To the best our knowledge, this is the first report that demonstrates the brain responses to cardiac electrical stimulation in humans. This new method should be useful for examining pathophysiology of cardiac diseases with pathological cardiac sensation, including cardiac anxiety and silent myocardial ischemia.

keywords —— cardiac afferent nerves; cardiac resynchronization therapy; cardiac sensation; electroencephalogram; pacemaker

© 2012 Tohoku University Medical Press

===============================

Tohoku J. Exp. Med., 2012, 226, 3-10

Correspondence: Hideaki Suzuki, M.D., Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.

e-mail: hd.suzuki.1870031@cardio.med.tohoku.ac.jp