Author's Note: Each patient education article in this column is written to your patients and potential patients. It draws on research documented in Somatovisceral Aspects of Chiropractic: An Evidence-Based Approach, co-edited by Marion Todres-Masarsky, DC. Whenever possible, I have updated the material from the textbook with more recent research findings.
As full-time practitioners in the Northern Virginia suburbs of Washington, D.C. (Vienna, Va.), my partner and I have noticed we are dealing with an increasingly sophisticated patient population. This probably is true of your practice as well. Most people do not know there is any connection between the spine and the heart. The following patient education article addresses some recent research in this area. Please feel free to use it on your bulletin board, for lay lectures and/or for your practice newsletter. I hope you find this article useful, and that your patient education efforts are successful in generating referrals. Thank you in advance for your referrals when your patients visit or move to northern Virginia!
Even if every nerve in your chest were disconnected, your heart would continue to beat. This is because a small node of heart muscle rhythmically contracts and relaxes on its own, setting the pace for your heartbeat. This natural pacemaker is called the "sinoatrial node." In the average adult, the sinoatrial node maintains a rhythm of approximately 70 beats per minute.
As impressive as this natural pacemaker is, it is a very limited control system. Left on its own, the sinoatrial node would keep your heart constantly beating at an invariable speed, whether you are exercising or resting, upset or relaxed, alert or asleep. Fortunately, the nerve supply to your heart provides accelerators and brakes. The accelerators - nerves that cause the heart rate to speed up - are called "sympathetic nerves." The sympathetic nerves to your heart originate from the thoracic spine (in your upper back). The brakes - the nerves that slow down heart rate - are called "parasympathetic nerves." The parasympathetic nerves to your heart originate from the brain itself, and pass very close to the upper cervical vertebrae as they pass through your neck on their way to your heart.
Over the years, chiropractic researchers have noted that chiropractic adjustments often are accompanied by a normalization of cardiac rhythm.1 This suggests that spinal misalignment or restriction (subluxation) can create an imbalance in the sympathetic and parasympathetic stimulation to the heart. A recent study made use of a specialized type of electrocardiographic measurement, which is a sensitive indicator of sympathetic/parasympathetic balance in the control of heart rhythm.2 This measurement is called heart rate variability (HRV).
Several chiropractic practices contributed HRV data from 539 chiropractic patients with no history of heart disease. Most of these patients had HRV readings done before and after a single adjustment, while 20 percent had their HRV measurements done before and after four weeks of care. In both groups, HRV at the end of the study was significantly better than HRV at the beginning of the study. Even though these patients had no known cardiac health problems, improved sympathetic/parasympathetic balance clearly is beneficial. Previous research data indicate that better HRV readings correlate with better cardiovascular fitness.
While much more research needs to be done in this area, this recent study is part of a growing body of literature indicating that chiropractic adjustments have implications beyond back pain. Doctors of chiropractic maintain that spinal health is neurological health, and neurological health is whole-body health.
References
- Masarsky CS, Cremata EE. "Chiropractic Care and the Cardiovascular System." In Masarsky CS, Todres-Masarsky M (Editors): Somatovisceral Aspects of Chiropractic: An Evidence-Based Approach. New York: Churchill Livingstone, 2001.
- Zhang J, Dean D, Nosco D, Strathopulos D, Floros M. Effect of chiropractic care on heart rate variability and pain in a multisite clinical study. Journal of Manipulative and Physiological Therapeutics, 2006;29:267-274.
Note: If you are interested in earning re-licensure credits with coursework on the somatovisceral aspects of chiropractic, online courses are available through New York Chiropractic College (www.nycc.edu).
