CEREBRAL HEMISPHERIC LATERALIZATION IN CARDIAC AUTONOMIC CONTROL

Objective: To identify cerebral hemispheric lateralization in cardiac autonomic control. Patients: Eight patients undergoing an intracarotid amobarbital sodium test as a presurgical evaluation of temporal lobe epilepsy. Design: Power spectral analysis of heart rate variability be fore and after intracarotid amobarbital injection. Setting: University hospital and research center. Main Outcome Measure: The changes in th e ratio of low-frequency (LF) (sympathetic) to high-frequency (HF) (pa rasympathetic) power (LF/HF ratio), a measure of sympathovagal balance , after hemispheric inactivation. Results: The LF/HF ratio changed as follows: right preinactivation = 3.81 +/- 0.96, postinactivation = 3.4 0 +/- 1.23; left preinactivation = 2.74 +/- 0.49, postinactivation = 4 .34 +/- 0.59 (mean +/- SEM). The test of interaction between lateralit y and inactivation using a 2-way repeated-measures analysis of varianc e was statistically significant (P = .001). The increased ratio on the left side (1.61 +/- 0.70) was statistically significant (P = .03), bu t the decrease on the right side (-0.40 +/- 0.46) was not (P less than or equal to .70). Conclusions: These findings suggest that there is a cerebral lateralization in cardiac autonomic control and that the rig ht cerebral hemisphere predominantly modulates sympathetic activity. T his study may help identify subgroups of patients with intracranial di sease at high risk of cardiac complications.