Heart Rate Variability Analysis in the Acupuncture Clinic: Correlation with Clinical Outcomes

This is the poster I presented last weekend at the ISAMS in Irvine. ISAMS stands for International Scientific Acupuncture and Meridian Symposium. How was the response to my poster? It was somewhat mixed but overall positive. Some of the researchers really "got" what I'm trying to do. Others really couldn't wrap their minds around the nonscientific nature of my study, and what the point was. What is the point? There is some profound response that happens during acupuncture in some patients. I can't give up on this project because when you see a profound response clinically to an acupuncture series or even session, my hunch is that HRV is a measure that is subtle enough to register that change physiologically. Now I only have to prove it... There are many confounding problems with HRV, time of day, body positioning, need for normal sinus rhythm, all of which mitigate the utility of HRV. However, as a modality to register change, at least in some responders, some of the time it might show what is happening that allows these dramatic effects.
What I incorporated for this study was Sample Entropy comparisons. It is a nonlinear measure of HRV which is less dependent on a pristine heart rate tracing, and hence more attractive for clinic use. To quote some other researchers on complexity measures

“The fractal organization of human HR dynamics is determined by a delicate interplay between sympathetic and vagal outflow, with the breakdown of fractal HR behavior toward more random dynamics occurring during coactivation of sympathetic and vagal outflow[i] A system’s complexity will be reflected in the dynamical fluctuations generated by the free-running conditions Complexity (healthy systems) > Complexity (pathologic systems) Healthy systems operating, far from equilibrium, have greater adaptability and functionality than pathologic systems, therefore• Disease, aging, drug toxicities should degrade complexity."

I would add STRESS decreases complexity, also.

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[i] Tulppo et al. Circulation 2005; 112:314-319

Introduction

The goal of these studies is to develop a system of

1. Reliable measurement of HRV (Heart Rate Variability) during acupuncture treatment to help guide and inform treatment.

2. To establish the utility of acupuncture as a stress reducing treatment.

3. To develop a dependable system of measurement to be used to correlate with more invasive and expensive measures of stress and health such as cortisol measurements, fMRI, EEG, or even telomere evaluations.

The Autonomic Nervous System and Acupuncture: Autonomic balance has been implicated in acupuncture’s results [i][ii]. Increased parasympathetic activity and decreased sympathetic activity can be beneficial to the patient by decreasing stress and elevated cortisol levels. Elevated cortisol and sympathetic tone and have an incalculable negative impact on pain, mood, immunity, longevity, and health in general.

HRV and Autonomic Nervous System: The basic concept of HRV is that within parameters, more complexity is a sign of greater health. HRV declines in old age, high stress, or a variety of illnesses. It is an indirect measure of sympathetic/parasympathetic tone. HRV is often measured after a physiological intervention, such as postural change, a cardiac stressor, or even mental challenges to assess autonomic tone and cardiac health.

Acupuncture and HRV: Acupuncture is a subtle intervention that achieves its results by triggering multiple neurotransmitters including local and central effects, and it may be possible to detect some of those changes by subtle changes in HRV. HRV has been studied with acupuncture in the laboratory setting, on healthy volunteers, and in the clinic on specific patients. HRV has been explored in conjunction with fMRI[iii] and EEG[iv] in the acupuncture context also. There are a few studies correlating HRV with positive clinical outcomes[v][vi][vii], but in general, HRV is for the most part relegated to studies, not as a practical tool to be used in the clinic. There is good reason for this. There are multiple confounds in combining clinical acupuncture and HRV, including the constraints of clinical practice and the propensity to artifact in cardiac monitoring. The author hypothesized that with the newer capabilities of Kubios shareware to analyze HRV with nonlinear methods, inclusion of nonlinear parameters could prove to be more reliable and sensitive to subtle shifts in HRV than linear methods.

With a decrease in the stress reponse, one would expect to see the following.

Fast Fourier Transform. A Decrease in the LFR/HFR from segment “a” (1 minute to 6 minutes) and “b” (minutes 6 to 11.)

Poincare Plots (SD1/SD2) are a valuable method which is a simple visualization tool, can identify ectopic beats so is less dependent on a pristine heart tracing.[viii] Would expect to see an increase in the SD1/SD2 between a and b segments.

Sample Entropy , SampEn is widely accepted as a more consistent and less biased complexity measure than Approximate Entropy. You would expect to see an increase in Sample Entropy from the first to the second time window.

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