How a Watch was used to Discover Heart Rate Variability (HRV) & How it’s Discovery has Led to Managing Wellness & Health.

Variability is the law of life… (Wiliam Osler, Physician and educator, 1849-1919 (Olser, 1903, p.327).
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The Rev. Stephen Hales (1733) was credited to be the first individual to notice that pulse varied with respiration via a watch with a second hand that could be paused, also known as the ‘Physician’s Pulse Watch”.

The first recording of RSA (Respiratory Sinus Arrhythmia, was conducted by Carl Ludwig in 1847.

The year, 1895 brought advanced insight and awareness into Heart Rate Variability (HRV) with the introduction of ECG (electrocardiogram). With advanced digital signal processing techniques developed throughout the 1960’s the relationship between HRV and disease was further investigated and the realization that health, wellness and disease has a direct correlation with HRV, particularly the lack of HRV.

Undoubtedly, early humans were aware of how our heart beats varied, increased and slowed, through exertion and sexual arousal. Nonetheless, the very first written report of Heart Rate (measured by pulse) were found in the writings of the Greek Physician and scientist Herophilos, 335-AC-280 BC.

Unfortunately, all of the original writings are lost. However, Greco-Roman physician Galen quoted the work of Herophilos extensively. Through these writings, we learned that Herophilos (280 BC-335 AC) used a water clock to time the pulse.waterclock

In 1915, Eppinger and Hess proposed that HRV could be used to identify abnormal autonomic function. Hess and Eppinger wrote “Clinical facts, such as respiratory, arryhythmia, habitual bradycardia, etc. have furnished the means of drawing our attention to variation in the tonus of the vagal system” (Eppinger and Hess, 1915. P. 12). Further, they stressed the pharmacological treatment of the cholinergic system could provide a valuable source for treatment (Eppinger and Hess, 1915).

During the 1960’s and 1970’s huge advancements were made in the study of HRV. Wolf, was the first to validate a clear relationship between HRV and mortality post myocardial infarction (Wolf, et al., 1978). Subsequently, this finding was confirmed by the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology, (1996; Bigger, 1977; Hohnloser et al., 1997; Thayler et al., 2010).

The study of HRV has gone from simplistic Time Domain Analysis in the early 1960’s to today’s’ more comprehensive non-linear dynamics—thanks to advancements in digital processing. (Billman, 2011, p. 86) HRV is an important tool used clinically to identify patients at risk for adverse cardiovascular events.

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