Respiratory Sinus Arrhythmia

Why Does the Heartbeat Synchronize With Respiratory Rhythm?
      Respiratory sinus arrhythmia (RSA) is heart rate variability in synchrony with respiration, by which the R-R interval on an ECG is shortened during inspiration and prolonged during expiration. Although RSA has been used as an index of cardiac vagal function, it is also a physiologic phenomenon reflecting respiratory-circulatory interactions universally observed among vertebrates. Previous studies have shown that the efficiency of pulmonary gas exchange is improved by RSA, suggesting that RSA may play an active physiologic role. The matched timing of alveolar ventilation and its perfusion with RSA within each respiratory cycle could save energy expenditure by suppressing unnecessary heartbeats during expiration and ineffective ventilation during the ebb of perfusion. Furthermore, evidence has accumulated of a possible dissociation between RSA and vagal control of that heart rate, suggesting differential controls between the respiratory modulation of cardiac vagal outflow and cardiac vagal tone. RSA or heart rate variability in synchrony with respiration is a biological phenomenon, which may have a positive influence on gas exchange at the level of the lung via efficient ventilation/perfusion matching.

      Key words


      RSA (respiratory sinus arrhythmia)
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        • Adrian ED
        • Bronk DW
        • Phillips G
        Discharges in mammalian sympathetic nerves.
        J Physiol. 1932; 74: 115-133
        • Rosenbaum M
        • Race D
        Frequency-response characteristics of vascular resistance vessels.
        Am J Physiol. 1968; 215: 1397-1402
        • Dornhorst AC
        • Howard P
        • Leathart GL
        Respiratory variations in blood pressure.
        Circulation. 1952; 6: 553-558
        • Ludwig C
        Beitra¨ge zur Kenntniss des Einflusses der Respirationsbewegungen auf den Blutlauf im Aortensysteme.
        Arch Anat Physiol Leipzig. 1847; 13: 242-302
        • Hamlin RL
        • Smith CR
        • Smetzer DL
        Sinus arrhythmia in the dog.
        Am J Physiol. 1966; 210: 321-328
        • Scher AM
        • Young AC
        Reflex control of heart rate in the unanesthetized dog.
        Am J Physiol. 1970; 218: 780-789
        • Hayano J
        • Yasuma F
        • Okada A
        • et al.
        Respiratory sinus arrhythmia: a phenomenon improving pulmonary gas exchange and circulatory efficiency.
        Circulation. 1996; 94: 842-847
        • Morgan BJ
        • Croix CMS
        • Skatrud JB
        Influence of respiration on autonomic control of heart rate and blood pressure.
        in: Bradley TD Floras JS Sleep apnea: implications in cardiovascular and cerebrovascular disease. Marcel Dekker, New York, NY2000: 1-31
        • Galletly DC
        • Larsen PD
        Relationship between cardioventilatory coupling and respiratory sinus arrhythmia.
        Br J Anaesth. 1998; 80: 164-168
        • Forster RE
        Diffusion of gases.
        in: Fenn WO Rahn H Handbook of physiology: the respiratory system (vol 1). American Physiological Society, Bethesda MD1964: 839-872
        • Yasuma F
        • Nomura H
        • Ogawa S
        • et al.
        Hemodynamic study of negative pressure ventilation using diaphragm pacing [in Japanese].
        Kokyu To Junkan. 1989; 37: 977-981
        • Lorenzi-Filho G
        • Dajani HR
        • Leung RST
        • et al.
        Entrainment of blood pressure and heart rate oscillations by periodic breathing.
        Am J Respir Crit Care Med. 1999; 159: 1147-1154
        • Yasuma F
        • Nomura H
        • Hayashi H
        • et al.
        Breathing abnormalities during sleep in patients with chronic heart failure.
        Jpn Cic J. 1989; 53: 1506-1510
        • Sin DD
        • Fitzgerald F
        • Parker JD
        • et al.
        Risk factors for central and obstructive sleep apnea in 450 men and women with congestive heart failure.
        Am J Respir Crit Care Med. 1999; 160: 1101-1106
        • Yasuma F
        • Hayano J
        Augmentation of respiratory sinus arrhythmia in response to progressive hypercapnia in conscious dogs.
        Am J Physiol. 2001; 280: H2336-H2341
        • Yasuma F
        • Hayano J
        Impact of acute hypoxia on heart rate and blood pressure variability in conscious dogs.
        Am J Physiol. 2000; 279: H2344-H2349
        • Pagani M
        • Lombardi F
        • Guzzetti S
        • et al.
        Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympatho-vagal interaction in man and conscious dog.
        Circ Res. 1986; 59: 178-193
        • Saul JP
        • Berger RD
        • Chen MH
        • et al.
        Transfer function analysis of autonomic regulation: II. Respiratory sinus arrhythmia.
        Am J Physiol. 1989; 256: H153-H161
        • 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 Neurosci. 1997; 51: 237-239
        • Hayano J
        • Taylor JA
        • Yamada A
        • et al.
        Continuous assessment of hemodynamic control by complex demodulation of cardiovascular variability.
        Am J Physiol. 1993; 264: H1229-H1238
        • Hayano J
        • Taylor JA
        • Mukai S
        • et al.
        Assessment of frequency shifts in R-R interval variability and respiration with complex demodulation.
        J Appl Physiol. 1994; 77: 2879-2888
        • Sasano N
        • Vesely AE
        • Hayano J
        • et al.
        Direct effects of PaCO2on respiratory sinus arrhythmia in conscious humans.
        Am J Physiol. 2002; 282: H973-H976
        • Goldberger JJ
        • Ahmed MW
        • Parker MA
        • et al.
        Dissociation of heart rate variability from parasympathetic tone.
        Am J Physiol. 1994; 266: H2152-H2157
        • Shykoff BE
        • Naqvi SSJ
        • Menon AS
        • et al.
        Respiratory sinus arrhythmia in dogs: effects of phasic afferents and chemostimulation.
        J Clin Invest. 1991; 87: 1621-1627
        • Rose Jr, CE
        • Althaus JA
        • Kaiser DL
        • et al.
        Acute hypoxemia and hypercapnia: increase in plasma catecholamines in conscious dogs.
        Am J Physiol. 1983; 245: H924-H929
        • Rowell LB
        • Johnson DG
        • Chase PB
        • et al.
        Hypoxia raises muscle sympathetic activity but not norepinephrine in resting humans.
        J Appl Physiol. 1989; 66: 1736-1743
        • Saito M
        • Mano T
        • Iwase S
        • et al.
        Responses in muscle sympathetic activity to acute hypoxia in humans.
        J Appl Physiol. 1988; 65: 1548-1552
        • Yasuma F
        • Hirai M
        • Hayano J
        Differential effects of hypoxia and hypercapnia on respiratory sinus arrhythmia in conscious dogs.
        Jpn Circ J. 2001; 65: 738-742
        • Hickling KG
        • Walsh J
        • Henderson S
        • et al.
        Low mortality rate in adult respiratory distress syndrome using low-volume, pressure-limited ventilation with permissive hypercapnia: a prospective study.
        Crit Care Med. 1994; 22: 1568-1578
        • Somers VK
        • Mark AL
        • Zavala DC
        • et al.
        Contrasting effects of hypoxia and hypercapnia on ventilation and sympathetic activity in humans.
        J Appl Physiol. 1989; 67: 2101-2106
        • Sanders MH
        • Keller FA
        Chronotropic effects of progressive hypoxia and hypercapnia.
        Respiration. 1989; 55: 1-10
        • Daly DM
        Interactions between respiration and circulation.
        in: Cherniack NS Widdicombe JG Handbook of physiology: the respiratory system (vol 2). American Physiological Society, Bethesda MD1986: 529-594
        • Horner RL
        • Brooks D
        • Kozar LF
        • et al.
        Respiratory-related heart rate variability persists during central apnea in dogs: mechanisms and implications.
        J Appl Physiol. 1995; 78: 2003-2013
        • Jewett DL
        Activity of single efferent fibers in the cervical vagus nerve of the dog with special reference to possible cardio-inhibitory fibers.
        J Physiol. 1964; 175: 321-357
        • Kunze DL
        Reflex discharge patterns of cardiac vagal efferent fibers.
        J Physiol. 1972; 222: 1-15
        • Davidson NS
        • Goldner S
        • McCloskey DI
        Respiratory modulation of baroreceptor and chemoreceptor reflexes affecting heart rate and vagal efferent nerve activity.
        J Physiol. 1976; 259: 523-530
        • Katona PG
        • Poitras JW
        • Barnett GO
        • et al.
        Cardiac vagal efferent activity and heart period in the carotid sinus reflex.
        Am J Physiol. 1970; 218: 1030-1037
        • Gilbey MP
        • Jordan D
        • Richter DW
        • et al.
        Synaptic mechanisms involved in the inspiratory modulation of vagal cardio-inhibitory neurons in the cat.
        J Physiol. 1984; 356: 65-78
        • Daly MD
        • Scott MJ
        The effects of stimulation of the carotid body chemoreceptors on heart rate in the dog.
        J Physiol. 1958; 144: 148-166
        • Katona PG
        • Jih F
        Respiratory sinus arrhythmia: noninvasive measure of parasympathetic cardiac control.
        J Appl Physiol. 1975; 39: 801-805
        • Eckberg DL
        Human sinus arrhythmia as an index of vagal cardiac outflow.
        J Appl Physiol. 1983; 54: 961-966
        • Camm AJ
        • Malik M
        • Bigger Jr, JT
        • et al.
        Heart rate variability- standards of measurement, physiological interpretation, and clinical use.
        Circulation. 1996; 93: 1043-1065
        • Anrep GV
        • Pascual W
        • Rössler R
        Respiratory variations of the heart rate: I. The reflex mechanism of the respiratory arrhythmia.
        Proc R Soc Lond B Biol Sci. 1936; 119B: 191-217
        • Katragadda S
        • Xie A
        • Puleo D
        • et al.
        Neural mechanism of the pressor response to obstructive and nonobstructive apnea.
        J Appl Physiol. 1997; 83: 2048-2054
        • Bernardi L
        • Keller F
        • Sanders M
        • et al.
        Respiratory sinus arrhythmia in the denervated human heart.
        J Appl Physiol. 1989; 67: 1447-1455
        • Hirsch JA
        • Bishop B
        Respiratory sinus arrhythmia in humans: how breathing pattern modulates heart rate.
        Am J Physiol. 1981; 241: H620-H629
        • Hayano J
        • Mukai S
        • Sakakibara M
        • et al.
        Effects of respiratory interval on vagal modulation of heart rate.
        Am J Physiol. 1994; 267: H33-H40
        • Hrushesky WJM
        • Fader D
        • Schmitt O
        • et al.
        The respiratory sinus arrhythmia: a measure of cardiac age.
        Science. 1984; 224: 1001-1004
        • Huikuri HV
        • Niemela¨ MJ
        • Ojala S
        • et al.
        Circadian rhythms of frequency domain measures of heart rate variability in healthy subjects and patients with coronary artery disease: effects of arousal and upright posture.
        Circulation. 1994; 90: 121-126
        • Vanoli E
        • Adamson PB
        • Lin B
        • et al.
        Heart rate variability during specific sleep stages: a comparison of healthy subjects with patients after myocardial infarction.
        Circulation. 1995; 91: 1918-1922
        • Dixon EM
        • Kamath MV
        • McCartney N
        • et al.
        Neural regulation of heart rate variability in endurance athletes and sedentary controls.
        Cardiovasc Res. 1992; 26: 713-719
        • Goldsmith RL
        • Bigger Jr, JT
        • Steinman RC
        • et al.
        Comparison of 24-hour parasympathetic activity in endurance-trained and untrained young men.
        J Am Coll Cardiol. 1992; 20: 552-558
        • Myers GA
        • Martin GJ
        • Magid NM
        • et al.
        Power spectral analysis of heart rate variability in sudden cardiac death: comparison to other methods.
        IEEE Trans Biomed Eng. 1986; 33: 1149-1156
        • Airaksinen KEJ
        • Ika¨heimo MJ
        • Linnaluoto MK
        • et al.
        Impaired vagal heart rate control in coronary artery disease.
        Br Heart J. 1987; 58: 592-597
        • Hayano J
        • Sakakibara Y
        • Yamada M
        • et al.
        Decreased magnitude of heart rate spectral components in coronary artery disease: its relation to angiographic severity.
        Circulation. 1990; 81: 1217-1224
        • Lishner M
        • Akselrod S
        • Avi VM
        • et al.
        Spectral analysis of heart rate fluctuations: a non-invasive, sensitive method for the early diagnosis of autonomic neuropathy in diabetes mellitus.
        J Auton Nerv Syst. 1987; 19: 119-126
        • Sakakibara M
        • Takeuchi S
        • Hayano J
        Effect of relaxation training on cardiac parasympathetic tone.
        Psychophysiology. 1994; 31: 223-228
        • Sakakibara M
        • Hayano J
        Effect of slowed respiration on cardiac parasympathetic response to threat.
        Psychosom Med. 1996; 58: 32-37
        • Taylor EW
        • Jordan D
        • Coote JH
        Central control of the cardiovascular and respiratory systems and their interactions in vertebrates.
        Physiol Rev. 1999; 79: 855-916
        • Butler PJ
        • Taylor EW
        Factors affecting the respiratory and cardiovascular responses to hypercapnic hypoxia in mallard ducks.
        Respir Physiol. 1983; 53: 109-127
        • Satchell GH
        The reflex co-ordination of the heartbeats with respiration in dogfish.
        J Exp Biol. 1960; 37: 719-730