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Communications to the Editor |

Heartbeat Synchronizes With Respiratory Rhythm Only Under Specific Circumstances FREE TO VIEW

Evgeny Vaschillo, PhD; Bronya Vaschillo, PhD; Paul Lehrer, PhD
Author and Funding Information

Affiliations: University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Piscataway, NJ,  University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ,  Suzuka National Hospital, Suzuka, Japan,  Nagoya City University School of Medicine, Nagoya, Japan

Correspondence to: Paul Lehrer, PhD, Department of Psychiatry, D-335, UMDNJ-Robert Wood Johnson Medical School, 671 Hoes Ln, Piscataway, NJ 08854; e-mail: lehrer@umdnj.edu



Chest. 2004;126(4):1385-1387. doi:10.1378/chest.126.4.1385-a
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To the Editor:

Yasuma and Hayano (February 2004)1 have theorized that respiratory sinus arrhythmia improves respiratory efficiency by the pairing of increases in heart rate with inhalation, when the concentration of oxygen in the alveoli is maximal. However, this phase relationship only occurs under specific circumstances.

Saul et al2 applied vagal and sympathetic blocking agents, and found that the phase lag from breathing to heart rate is near 0°, but only under pure vagal conditions. Under pure sympathetic conditions, the phase relationship varies from 180° at low frequencies to approximately −180° at high frequencies.

We asked eight healthy subjects to breathe at seven frequencies between 0.04 and 0.5 Hz for 2 min each, matching their strain-gauge respiration record to a computer-generated sine curve3 to ensure a constant respiratory depth and a sinusoidal shape for respiratory curves. Using Fourier filtration,3 we determined that the phase relationship between heart rate and respiration was 0° only at a respiratory frequency of approximately 0.1 Hz, in which the target frequency heart rate variability also was highest (Fig 1 ).

When healthy people breathe regularly at this resonant frequency for the cardiovascular system, we also found that the baroreflexes are systematically stimulated and baroreflex gain increases.4 In addition, peak expiratory flow improves.4There also is preliminary evidence for an improvement in clinical asthma,5and for improvement in respiratory gas exchange efficiency and clinical function in COPD patients.6

Thus, the hypothesis of Yasuma and Hayani1 would be specifically relevant for sympathetically medicated heart rate variability, or for respiratory sinus arrhythmia associated with slow breathing at approximately 0.1 Hz.

Figure 1.Transfer function of respiration (input) to heart rate (output). Values given as the mean of eight subjects.

Grahic Jump LocationTransfer function of respiration (input) to heart rate (output). Values given as the mean of eight subjects.

Figure Jump LinkFigure 1. Transfer function of respiration (input) to heart rate (output). Values given as the mean of eight subjects.Grahic Jump Location
Yasuma, F, Hayano, J (2004) Respiratory sinus arrhythmia: why does the heartbeat synchronize with respiratory rhythm?Chest125,683-690. [CrossRef]
 
Saul, JP, Berger, RD, Albrecht, P, et al Transfer function analysis of the circulation: unique insights into cardiovascular regulation.Am J Physiol Heart Circ Physiol1991;261,H1231-H1245
 
Vaschillo, E, Lehrer, P, Rishe, N, et al Heart rate variability biofeedback as a method for assessing baroreflex function: a preliminary study of resonance in the cardiovascular system.Appl Psychophysiol Biofeedback2002;27,1-27. [CrossRef]
 
Lehrer, PM, Vaschillo, E, Vaschillo, B, et al Heart rate variability biofeedback increases baroreflex gain and peak expiratory flow.Psychosom Med2003;65,796-805. [CrossRef]
 
Lehrer, PM, Vaschillo, E, Vaschillo, B, et al Biofeedback treatment for asthma.Chest2004;126,352-361. [CrossRef]
 
Giardino, N, Chan, L, Borson, S Combined heart rate variability and pulse oximetry biofeedback for chronic obstructive pulmonary disease: a feasibility study.Appl Psychophysiol Biofeedback2004;29,121-133. [CrossRef]
 
To the Editor:

We appreciate the interest by Drs. Vaschillo and Lehrer in our Opinions/Hypothesis article (February 2004)1on respiratory sinus arrhythmia (RSA). We agree with their comment that heartbeat synchronizes with respiratory rhythm only under certain conditions, so that the results of the physiologic experiment are only applicable to the model used in the study. In their well-organized investigation,2 Vaschillo and coworkers2 used healthy subjects who were strictly instructed to breathe in synchrony with the extrinsic pacemaker (ie, a metronome) at predetermined respiratory frequencies between 0.04 and 0.5 Hz for 2 min. As was noted in our Opinions/Hypothesis article,,1 humans are a species with a weak RSA compared with dogs. Moreover, a paced breathing that is in synchrony with the extrinsic rhythm generator might precipitate mental stress for subjects, and the equilibrium state of CO2/O2 metabolism through the paced breathing could not have been obtained in a very short period of time. Such factors as species, state of the subjects (ie, very alert, alert, relaxed, or asleep), and metabolism should always be considered in clinical/basic experiments on the synchrony of heartbeat with respiratory rhythm. Therefore, for this purpose we used trained dogs to lie down in a relaxed state under spontaneous breathing,,35 as dogs are a species with a strong RSA.

The phase relationship between heart rate and respiration shows frequency dependence, but the relationship is known to be nonlinear.6 Eckberg6has reported that the phase analysis between heart rate and respiration shows a clear hysteresis, and that the prolongation of the R-R interval begins shortly after the onset of expiration independently of respiratory frequency. He has also demonstrated that the shortening of the R-R interval begins progressively earlier in reference to the onset of inspiration as respiratory frequency decreases. As a result, the timing of the maximum instantaneous heart rate occurs instantly after end-inspiration, with the maximal lung volume at least for a respiratory frequency of < 0.25 Hz. Although the phase of the maximum heart rate lags behind the phase of the maximum lung volume as respiratory frequency increases, the amplitude of RSA decreases progressively.7 These facts seem to be consistent with the hypothesis that RSA is a function of physiologic respite for the cardiovascular and respiratory systems in resting animals and humans, because the phase relationship at a reduced respiratory frequency is optimal to cardiac and respiratory energy savings by reducing unnecessary heartbeats during expiration and unnecessary ventilation during the waning phase of the heart beat.1,8

References
Yasuma, F, Hayano, J Respiratory sinus arrhythmia: why does the heartbeat synchronize with respiratory rhythm?.Chest2004;125,683-690. [CrossRef]
 
Vaschillo, E, Lehrer, P, Rishe, N, et al Heart rate variability biofeedback as a method for assessing baroreflex function: a preliminary study of resonance in the cardiovascular system.Appl Psychophysiol Biofeedback2002;27,1-27. [CrossRef]
 
Yasuma, F, Hayano, J Augmentation of respiratory sinus arrhythmia in response to progressive hypercapnia in conscious dogs.Am J Physiol Heart Circ Physiol2001;280,H2336-H2341
 
Yasuma, F, Hayano, J Impact of acute hypoxia on heart rate and blood pressure variability in conscious dogs.Am J Physiol Heart Circ Physiol2000;279,H2344-H2349
 
Yasuma, F, Hayashi, H, Shimokata, K, et al Recording of electroencephalograms and electrocardiograms during daytime sleep in trained canines: preparation of the sleeping dogs.Psychiatry Clin Neurosci1997;51,237-239. [CrossRef]
 
Eckberg, DL Human sinus arrhythmia as an index of vagal cardiac outflow.J Appl Physiol1983;54,961-966
 
Hayano, J, Mukai, S, Sakakibara, Y, et al Effects of respirtory interval on vagal modulation of heart rate.Am J Physiol Heart Circ Physiol1994;267,H33-H40
 
Hayano, J, Yasuma, F Hypothesis: respiratory sinus arrhythmia is an intrinsic resting function of cardiovascular system.Cardiovasc Res2003;58,1-9. [CrossRef]
 

Figures

Figure Jump LinkFigure 1. Transfer function of respiration (input) to heart rate (output). Values given as the mean of eight subjects.Grahic Jump Location

Tables

References

Yasuma, F, Hayano, J (2004) Respiratory sinus arrhythmia: why does the heartbeat synchronize with respiratory rhythm?Chest125,683-690. [CrossRef]
 
Saul, JP, Berger, RD, Albrecht, P, et al Transfer function analysis of the circulation: unique insights into cardiovascular regulation.Am J Physiol Heart Circ Physiol1991;261,H1231-H1245
 
Vaschillo, E, Lehrer, P, Rishe, N, et al Heart rate variability biofeedback as a method for assessing baroreflex function: a preliminary study of resonance in the cardiovascular system.Appl Psychophysiol Biofeedback2002;27,1-27. [CrossRef]
 
Lehrer, PM, Vaschillo, E, Vaschillo, B, et al Heart rate variability biofeedback increases baroreflex gain and peak expiratory flow.Psychosom Med2003;65,796-805. [CrossRef]
 
Lehrer, PM, Vaschillo, E, Vaschillo, B, et al Biofeedback treatment for asthma.Chest2004;126,352-361. [CrossRef]
 
Giardino, N, Chan, L, Borson, S Combined heart rate variability and pulse oximetry biofeedback for chronic obstructive pulmonary disease: a feasibility study.Appl Psychophysiol Biofeedback2004;29,121-133. [CrossRef]
 
Yasuma, F, Hayano, J Respiratory sinus arrhythmia: why does the heartbeat synchronize with respiratory rhythm?.Chest2004;125,683-690. [CrossRef]
 
Vaschillo, E, Lehrer, P, Rishe, N, et al Heart rate variability biofeedback as a method for assessing baroreflex function: a preliminary study of resonance in the cardiovascular system.Appl Psychophysiol Biofeedback2002;27,1-27. [CrossRef]
 
Yasuma, F, Hayano, J Augmentation of respiratory sinus arrhythmia in response to progressive hypercapnia in conscious dogs.Am J Physiol Heart Circ Physiol2001;280,H2336-H2341
 
Yasuma, F, Hayano, J Impact of acute hypoxia on heart rate and blood pressure variability in conscious dogs.Am J Physiol Heart Circ Physiol2000;279,H2344-H2349
 
Yasuma, F, Hayashi, H, Shimokata, K, et al Recording of electroencephalograms and electrocardiograms during daytime sleep in trained canines: preparation of the sleeping dogs.Psychiatry Clin Neurosci1997;51,237-239. [CrossRef]
 
Eckberg, DL Human sinus arrhythmia as an index of vagal cardiac outflow.J Appl Physiol1983;54,961-966
 
Hayano, J, Mukai, S, Sakakibara, Y, et al Effects of respirtory interval on vagal modulation of heart rate.Am J Physiol Heart Circ Physiol1994;267,H33-H40
 
Hayano, J, Yasuma, F Hypothesis: respiratory sinus arrhythmia is an intrinsic resting function of cardiovascular system.Cardiovasc Res2003;58,1-9. [CrossRef]
 
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