The effect of provocative maneuvers on heart rate variability in subjects with quadriplegia. Grimm, David R., Ronald E. Demeersman, Robert P. Garofano, Ann M. Spungen, and William A. Bauman. Spinal Cord Damage Research Center, Veterans Affairs Medical Center, Bronx, NY, Mount Sinai Medical Center, New York, NY, and Teachers College, Columbia University, New York, NY.
APStracts 2:0024H, 1995.
This study investigated heart rate variability (HRV) in individuals with quadriplegia who have disruption of autonomic control of the heart. Seven male subjects with neurological complete and seven with incomplete quadriplegia were studied at rest and during provocation. HRV was measured by power spectral analysis using a fast Fourier transform. Two spectral components were generated: the high frequency (HF) peak, a reflection of parasympathetic activity, and the low frequency (LF) peak, primarily sympathetic activity with some parasympathetic input. Results of the provocative maneuvers were grouped into one composite variable. Significant differences in the LF spectral component were found between the groups with complete and incomplete lesions in the supine position and after provocation (LF supine: p=0.01 and LF provocation: p=0.002). After provocation significant differences were demonstrated in the HF spectral component between these groups (p=0.005). In contrast to previous findings, a LF component in subjects with complete quadriplegia was observed; this LF component decreased after provocation, suggesting the parasympathetic component withdrew during stressful maneuvers. There also appeared to be general down-regulation of parasympathetic activity to the heart in subjects with complete quadriplegia. The presence of an increased LF spectral component during provocation in those with incomplete lesions implies sympathetic stimulation of the heart and may be used as a marker of sympathetic activity in individuals with quadriplegia. 

Received 18 July 1994; accepted in final form 4 January 1995.
APS Manuscript Number H627-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 February 1995.