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Heart Rate Variability, Physical Activity, and Cardiovascular Health in SCI

Principal Investigators: Jonathan Myers, PhD and B Jenny Kiratli, PhD

Project Staff: Wilsa Charles, MA; Amy Hayes, PT, MS; Gail O'Mara, BS; and Anthony Yin, BS

Project Category: Spinal Cord Injury - 2001

Objective: The overriding goal of this study will be to characterize "normal" heart rate variability (HRV) in individuals with SCI and examine these responses in the context of autonomic function/dysfunction. In addition, we will evaluate the association between habitual physical activity and heart rate variability in these individuals. Further, we will explore if there are differences in HRV in individuals with SCI who have symptoms or diagnoses of heart disease compared with those who are disease-free. The key questions are as follows:

  1. How does HRV in healthy individuals with SCI differ from HRV in ambulatory individuals?
  2. Is HRV influenced by autonomic function/dysfunction relative to lesion level and completeness?
  3. What is the effect of level of physical activity on HRV in individuals with SCI?
  4. Are changes in HRV associated with cardiovascular disorders in individuals with SCI?

Our long-term goals, beyond the purview of the current proposal, are to:

  1. assess the extent to which HRV can be used to predict future cardiovascular events,
  2. evaluate whether exercise training can influence HRV, and
  3. determine if changes in cardiac risk following intervention (such as exercise) can be detected in individuals with SCI.

Research Plan: Cardiovascular disease, the leading cause of morbidity in SCI, is thought to be attributable largely to the sedentary lifestyle and reduced physical function secondary to loss of motor function. This study will characterize the association between cardiovascular risk and daily physical activity status and apply tools to identify and characterize the presence of cardiovascular risk in SCI. This will provide an important step toward reducing the high cardiovascular morbidity and mortality associated with this condition.

In addition this study will begin to quantify the presence, and degree of autonomic dysfunction that is characteristic of SCI and demonstrate the relationship between abnormal HRV and reduced physical activity patterns. Analysis of variations in beat-to-beat intervals of heart rate, or heart rate variability (HRV) represents a promising marker of autonomic dysfunction. HRV has recently been shown to be a strong predictor of mortality in the elderly and in patients with chronic heart failure. Evidence suggests that HRV is abnormal in SCI relative to able-bodied individuals but no prior study has investigated whether changes in HRV are associated with cardiovascular symptoms or disease.

Recruitment: Currently recruiting individuals with SCI or ambulatory comparison participants in the Palo Alto, CA area.

Funding Source: VA RR&D Merit Review

Funding Status: Funded

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