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- Title
Neurocardiac Responses to Vagoafferent Electrostimulation in Humans.
- Authors
Mark V. Kamath; Adrian R.M. Upton; Andrew Talalla; Ernest L. Fallen
- Abstract
To determine if cardiac vagal tone is enhanced by vagal electrostimulation (VES), we examined (he heart rate autospectrum (HRA) in eight patients with implanted stimulators for complex partial seizures. In four patients the VES was activated at 30 Hz and 500-msec pulse (HiStim group) compared to 2 Hz and 130- msec pulse for the LoStim group (n = 4). Continuous ECG and respiratory waveforms were recorded for 45 minutes every 8 hours (7-8 AM; 3-4 FM 11-12 PM) during resting supine wakeful epochs both before and 15 days after surgical implantation. From the HRA cardiac sympathovagal balance was expressed as the ratio of the low frequency (LF) power to the high frequency (HF) power. RESULTS: There were no presurgical differences between the groups in heart rate, its variance, or the energies contained in any autospectral band, The LoStim group showed no significant change in heart rate (HR), HE peak power, or LE.HF ratios during 2 weeks of VES. Conversely, in the HiStim group, the LF.HF peak power ratio (an expression of sympathetic dominance) decreased from 2.5 ± 1.5 preimplant to 1.5 ± 0.49 (P < 0.02) with VES. During VES there was a significantly higher HE power in the HiStim compared to LoStim group. No diurnal variations in HHA values were seen for either group. CONCLUSIONS; (1) A relationship exists between selective vagal nerve electrostimulation and the HRA; and (2) high stimulation frequency ofthe vagus nerve in man is associated with sustained augmentation of cardiac vagal tone throughout a 24-hour cycle.
- Subjects
ELECTRIC stimulation; SPASM treatment; HEART beat; VAGUS nerve; ELECTROTHERAPEUTICS; ELECTROCARDIOGRAPHY
- Publication
Pacing & Clinical Electrophysiology, 1992, Vol 15, Issue 10, p1581
- ISSN
0147-8389
- Publication type
Article
- DOI
10.1111/j.1540-8159.1992.tb02937.x