Upon hearing of Evgeny Vaschillo’s passing, tributes poured in from throughout the world, including the following:

“…what a loss. His memory will live on through his amazing work!” (Richard Gevirtz).

“Dr. Vaschillo’s work is foundational to much of what I do every day for the children I serve. I am forever indebted to him for his pioneering research.” (Ethan Benore).

“His work is foundational to everything in HRV biofeedback, he is also a key citation for any research in this area” (Patrick Steffen).

“Our field lost a great scientist and a great human being, an inspiration to us all.” (Inna Khazan).

“Evgeny inspired my students and me. We will miss his brilliance and generosity of spirit.” (Fred Shaffer).

“Evgeny was one of a kind. Yes he always had that smile on his face and that infectious laugh… It always amazed me how little I was able to communicate with him in English and yet felt like we really got to know each quite well over the years…Truly amazing how groundbreaking his work was and how it laid the foundation for so much of the mainstream HRV work that is being done now. I will miss him.” (Jonathan Feldman).

“…I am profoundly grateful for his passion for teaching and mentorship. Evgeny had an open door policy as a mentor, unfailingly making himself available for questions and inspirational discussions. I remember his smile, compassion and humor so vividly.” (Leah Lagos).

“What a terrible loss for all of us personally, the scientific community, and the world. I will never forget Evgeny’s genius and profound goodness. He was a great mentor and colleague, and will never be forgotten.” (David Eddie).

Evgeny and Bronya treated me warmly, when I visited the Alcohol institute in Rutgers… Evgeny gave me many valuable comments on my research…I pray from the bottom of my heart that his soul may rest in peace.” (Masahito Sakakibara).

Evgeny grew up in St. Petersburg (then Leningrad), Russia. He received a masters degree in electromechanical engineering, specializing in design of medical equipment for space research at the Leningrad (now St. Petersburg) University for Aerospace Instrumentation Technology (1968), and then served in the Soviet military. In 1985 he received his Ph.D from the department of Human and Animal Physiology, at the Scientific Research Institute for Experimental Medicine of the Academy of Medical Sciences of the USSR, Leningrad. His dissertation had the arcane title of “Dynamics of Slow-Wave Cardiac Rhythm Structure as an Index of the Functional State of a Human-Operator”. This work, combining his expertise in both engineering and physiology, has been the basis of all subsequent research on heart rate variability biofeedback. It has since been published in English (Vaschillo et al., 2002).

In his career he authored or coauthored more than 50 journal articles, and presented more than 100 papers at scientific meetings. He received the Distinguished Scientist award from AAPB (2018) and was named a Lifetime Honorary Fellow of the AAPB in 2019. He held positions as associate professor of psychophysiology and head of the physiology laboratory at the Peter Lesgaft Academy of Physical Culture (the major institute for training Olympic athletes in the USSR), and held a senior position at a rehabilitation institute, the Biosvyaz Corporation, which spearheaded widespread clinical use of heart rate variability biofeedback in Russia and manufacture of equipment to perform it. In the United States he held research positions at the Veterans Administration Hospital, East Orange, NJ, and at Rutgers University, where he attained the position of associate professor.

In his seminal paper on the “functional state of the human operator,” based on experiments done on Russian cosmonauts, he used the engineering approach of transfer function analysis to study the interactions among oscillatory patterns in heart rate, blood pressure, and breathing. Through this, he demonstrated that effects of resonance in the baroreflex system, which, when rhythmically stimulated at resonance frequency, produced very high-amplitude oscillations in heart rate. At this singular rate, heart rate and breathing oscillated synchronously in phase with each other, such that increases in heart rate occurred simultaneously with inhalation and decreases with exhalation, while heart rate and blood pressure oscillated exactly in an opposing phase relationship, with increases in heart rate occurring simultaneously with decreases in blood pressure and decreases in heart rate with increases in blood pressure. The relationship between heart rate and blood pressure thus reflected operation of the baroreflexes, whereby increases in blood pressure stimulate decreases in heart rate and vice versa for decreases in blood pressure, thus providing homeostatic control of blood pressure by the effect of heart rate on blood flow. Evgeny showed how resonance in the baroreflex system at this rate produced maximally high-amplitude oscillations in heart rate, with the implication that it also produced maximally high stimulation of the baroreflex. An English language version of this research was published in Applied Psychophysiology and Biofeedback (Vaschillo et al., 2002). Later research together in my laboratory showed that regular practice of baroreflex-stimulation by this method exercised the baroreflex, thus strengthening it (Lehrer et al., 2003), and thus showing promise of improving modulation of a host of processes affected by the cardiovascular system. This is the basis of all current applications of heart rate variability biofeedback. He later expanded his analyses of resonance, finding that the resonance frequency does not vary over time during HRV biofeedback training, and that it tends to be related to the individual’s blood volume (Vaschillo et al., 2006). He also found that stimulation of the baroreflex at resonance frequency, with similar results, could be performed by other procedures that influenced cardiovascular activity, including rhythmical muscle tension (Lehrer et al., 2009) and rhythmical presentation of emotion-producing pictures (Vaschillo et al., 2008).

Although Evgeny had an interest in the various applications of heart rate variability biofeedback, his real passion was for understanding the various physiological ramifications of the oscillations in physiological parameters and how they were affected by various resonance systems. In addition to his work on the heart rate component of the baroreflex system, he also found resonances in cardiac output and in vascular tone at specific frequencies, and showed how stimulation of the system at much slower frequencies, in the range of 2–4 times a minute, produced resonant oscillations in variables related to vascular tone (Buckman et al., 2015; Vaschillo et al., 2002, 2012, 2015, 2020). It is a tragedy for our science that he did not have the opportunity to expand his work to applications that might directly affect vascular tone, and thus stimulate control of the sympathetic system much as heart rate variability biofeedback stimulates parasympathetic control. One could thereby investigate processes that might more directly affect vascular control, which is more directly involved in hypertension.

In his last years, Evgeny also became involved in fMRI investigation of baroreflex rhythms in the brain stimulated by breathing at the resonance frequency of the heart rate—baroreflex system. His preliminary analyses, reported at his Distinguished Scientist lecture at AAPB, showed how resonance frequency breathing induced connective oscillations among brainstem areas that generate emotion (amygdala and insula) and cortical areas involved in controlling it (prefrontal and cingulate cortices), and also areas involved in muscle and eye-muscle coordination (cerebellum and occipital cortex). Although refinements in analyses of these data remain ongoing, they show promise of explaining why heart rate variability biofeedback affects emotional regulation, with greater connectivity between oscillations induced in heart rate with those in the amygdala and with those in the cingulate cortex and prefrontal cortex (for modulation of emotional reactivity). It also may explain the beneficial effects of heart rate variability biofeedback on athleti and/artistic performance, from greater connectivity with the occipital cortex and cerebellum (for improved muscle and eye/muscle coordination). See paper by Lehrer in this issue for the clinical effects.

Throughout his career, Evgeny generously gave of his time to students, colleagues, and trainees from various fields -- engineering, physiology, psychology, kinesiology, exercise science, etc. His one limitation was a failure to master the intricacies of the English language. Yet, despite this, the power of his findings, aided by his good humor, and his cheerful enthusiasm and willingness to share his expertise, worked together to spread his influence widely.

One cannot review Evgeny’s accomplishments and influence without mentioning a major catalyst for everything he did. Throughout his career in the United States, his work could not have succeeded as it did without the constant aid and support of his loyal and loving wife Bronya, trained originally as a public health physician, who was always by his side. She was instrumentally involved in all of his work, and was a coauthor on almost all of his publications.

Privately, Evgeny was fond of describing how Russian applications of heart rate variability biofeedback were used in Russian clinics to treat a variety of neurotic disorders, and how athletes he trained at the Lesgaft Academy greatly improved performance in various athletic competitions after training in heart rate variability biofeedback. We have not seen objective Russian data demonstrating all of these effects. Perhaps it will emerge someday. Nevertheless, the increasingly large quantity of research now being conducted in the rest of the world appears to be expanding the proof of powerful biofeedback effects. This is all taking place because of the fundamental and inspirational work of Evgeny Vaschillo.

To commemorate the life and work of Dr. Vaschillo, in this issue of Applied Psychophysiology and Biofeedback we deviate somewhat from our format of more formal presentation of scientific research. We have asked productive researchers from around the world who have specialized in heart rate variability biofeedback research to review the work that has emanated from their own laboratories and those of their students and collaborators. We hope that these reviews will help focus future research in this field, and thereby continue to expand upon Evgeny’s legacy.