Sympathovagal balance of the heart in subjects with spinal cord
injury.
Grimm, David R., Ronald E. De Meersman, Peter L. Almenoff, Ann M.
Spungen, and William A. Bauman.
Spinal Cord Damage Research Center, Veterans Affairs Medical
Center, Bronx, NY, Department of Medicine, Mount Sinai Medical
Center, New York, NY, and Department of Rehabilitation Medicine,
College of Physicians and Surgeons, Columbia University, New York,
NY
APStracts 3:0348H, 1996.
This study investigated the effect of abnormal autonomic
cardiovascular function on HRV in individuals classified into four
groups: complete quadriplegia, incomplete quadriplegia, low
paraplegia, and non-spinal cord injury (SCI) controls. Measurements
were collected at baseline and during provocative maneuvers. Spectral
analysis using a fast Fourier transform algorithm revealed two
spectral components of HRV, termed low frequency (LF) and high
frequency (HF); the LF:HF ratio (estimate of sympathovagal balance)
was also calculated. Each group of subjects with quadriplegia
exhibited significantly lower spectral components for both baseline
and composite provocative measures compared with the nonSCI controls
(p<0.05). In addition, the group with paraplegia demonstrated
significantly lower HF baseline and LF composite levels than controls
(p<0.05). No differences were observed among all groups for the
LF:HF ratio. This consistency in the LF:HF ratio suggests that the
two autonomic divisions that regulate the cardiovascular system
maintain homeostasis even when one component is severely compromised.
This is supported by the additional findings of decreased
parasympathetic activity in the two groups with quadriplegia, as well
as the absence of significant differences among any of the four
groups at rest in either heart rate or blood pressure.
Received 26 December 1995; accepted in final form 6 August 1996.
APS Manuscript Number H1203-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 August 1996