I am excited to share with you an important biometric that we are able to observe with Valsalva Wave Pro, the new Coherence instrument. I am presently calling this biometric the “whole Valsalva Wave,” whole because it provides us with a much more complete view of what the blood is doing, including respiratory, heart beat, and vascular components, than traditional heart rate variability (HRV) measures.Figure 1 depicts blood rising and falling in the left index ﬁnger during Coherent Breathing as captured by the Valsalva Wave instrument. The large waves are a function of respiration. The shorter waves riding on the respiratory waves are the heart beats or “pulses”, their peaks being the cardiac systole, their valleys, the cardiac diastole. As the respiratory wave crests during exhalation, the amplitude of pulses increase and heart rate slows; as the respiratory wave troughs during inhalation, pulse amplitude decreases and heart rate increases. The larger pulses, riding atop the respiratory wave carry more blood and are a function of increased heart output coincident with increased pulmonary output during exhalation. The smaller pulses resting in the trough are a consequence of decreased heart output coincident with decreased pulmonary output during inhalation.
The Valsalva Wave instrument employs an optical DC plethysmograph. For our purposes, a plethysmograph allows us to observe the action of the blood noninvasively in a specific body part, for example the ﬁnger, thumb, earlobe, etc. The “DC” (direct current) plethysmograph is designed to capture a wide frequency spectrum, allowing us to see blood phenomena that are rapid, for example the heart beat, as well as actions that are much slower, specifically blood phenomena relating to respiration. We can use this information to further our understanding of how the body works, and for biofeedback, in this case training of the Valsalva Wave.The conventional plethysmographic device is “AC”, standing for “alternating current”. Basically this means that the raw signal is ﬁltered to exclude everything but the relatively rapid heart beat. The AC plethysmograph is the basis of all heart rate variability instruments that we’re familiar with where it has been used as the principal means of detecting the heart beat and pulse wave. Once detected, the interval between beats can be measured and when divided into 60 seconds yields the instantaneous heart beat rate in the familiar “beats per minute.” From this, the heart rate variability (HRV) graph is plotted.
Figure 2 presents simultaneous “AC” pulse wave and “DC” Valsalva Wave views. The AC pulse wave contains much of the information contained in the Valsalva Wave including inter beat interval, pulse amplitude, and the dicrotic notch (a function of arterial compliance/elasticity and autonomic governance of arterial dimensions). However, you can see what happens once the signal is “ﬁltered” – it loses its overall context (i.e., the fact that the pulse rides on the variable surface of the blood, much as waves ride on the surface of the ocean). Referring to the Valsalva Wave (bottom graph), we can clearly see pulse amplitude rising and falling as well as pulse rate decreasing and increasing, as a function of blood volume rising and falling. This is perfectly consistent with the current understanding of the “thoracic pump” and of the elegant coordination that exists between respiration, the heart, and autonomic governance of blood ﬂow and pressure.
I’m particularly excited about this whole Valsalva Wave. I believe it represents a key advancement in our understanding of the subtle mechanics of cardiopulmonary resonance as well as providing a compelling new biometric for feedback purposes. It is interesting to note that this “whole Valsalva Wave” is the blood aspect of the “pulse” that acupuncturists assess at the wrist when “taking the pulse” (recognizing that there is also an energy aspect).
This excerpt was taken from the July 2009 edition of The Coherence Newsletter.
Thank you for your interest and consideration,
Stephen Elliott is the principle author of The New Science of Breath
and Coherent Breathing: The Definitive Method. He is an avid heart rate variability researcher and the inventor of the “Coherent Breathing” method as well as “Valsalva Wave Pro” – an instrument that monitors the blood wave in the circulatory system produced during resonant breathing (See www.coherence.com and www.valsalvawave.com, respectively).
Reproduced with permission: Stephen Elliot.