Heart rate variability: a review

U. Rajendra Acharya1, K. Paul Joseph2, N. Kannathal1, C.M. Lim1, Jasjit S. Suri3,4
1Department of ECE, Ngee Ann Polytechnic, Singapore, Singapore
2Electrical Engineering, National Institute of Technology Calicut, Calilcut, India
3Biomedical Technologies Inc., Westminster, USA
4Idaho’s Biomedical Research Institute, ID, USA

Tóm tắt

Từ khóa


Tài liệu tham khảo

Acharya UR, Min LC, Joseph P (2002) HRV analysis using correlation dimension and DFA. Innov Tech Biol Med (ITBM-RBM) 23:333–339

Acharya UR, Bhat PS, Iyengar SS, Rao A, Dua S (2003) Classification of heart rate using artificial neural network and fuzzy equivalence relation. Pattern Recogn 36:61–68

Acharya UR, Kannathal N, Krishnan SM (2004) Comprehensive analysis of cardiac health using heart rate signals. Physiol Meas J 25:1130–1151

Acharya UR, Kannathal N, Seng OW, Ping LY, Chua T (2004) Heart rate analysis in normal subjects of various age groups. Biomed Online J USA 3(24)

Akaike H (1969) Fitting autoregressive models for prediction. Ann Inst Stat Math 21:243–247

Akaike H (1974) A new look at statistical model identification. IEEE Trans Autom Control 19:716–723

Akay M (2001) Nonlinear biomedical signal processing dynamic analysis and modeling, vol II. IEEE Press, New York

Akselrod S, Gordon D, Ubel FA, Shannon DC, Barger MA, Cohen RJ (1981) Power spectrum analysis of heart rate fluctuation. Science 213:220–222

Akselrod S, Gordon D, Madwed J, Snidman N, Shannon D, Cohen R (1985) Hemodynamic regulation: investigation by spectral analysis. Am J Physiol 249:H867–H875

Axelrod S, Lishner M, Oz O, Bernheim J, Ravid M (1987) Spectral analysis of fluctuations in heart rate: an objective evaluation of autonomic nervous control in chronic renal failure. Nephron 45:202–206

Barutcu I, Esen AM, Kaya D, Turkmen M, Karakaya O, Melek M, Esen OB, Basaran Y (2005) Cigarette smoking and heart rate variability: dynamic influence of parasympathetic and sympathetic maneuvers. Ann Noninvas Electrocardiol 10(3):324–329

Bekheit S, Tangella M, el-Sakr A, Rasheed Q, Craelius W, el-Sherif N (1990) Use of heart rate spectral analysis to study the effects of calcium channel blockers on sympathetic activity after myocardial infarction. Am Heart J 119:79–85

Berger RD,Akselrod S,Gordon D,Cohen RJ (1986) An efficient algorithm for spectral analysis of heart rate variability. IEEE Trans Biomed Eng 33:900–904

de Boer RW, Karemaker JM, Strackee J (1985) Relationships between short-term blood-pressure fluctuations and heart-rate variability in resting subjects. I: a spectral analysis approach. Med Biol Eng Comput 23(4):352–358

de Boer RW, Karemaker JM, Strackee J (1985) Relationships between short-term blood-pressure fluctuations and heart-rate variability in resting subjects. II: a simple model. Med Biol Eng Comput 23(4):359–64

de Boer RW, Karemaker JM, Strackee J (1985) Spectrum of a series of point events, generated by the integral pulse frequency modulation model. Med Biol Eng Comput 23(2):138–142

Bonnemeier H, Wiegand UKH, Brandes A, Kluge N, Katus HA, Richardt G, Potratz J (2003) Circadian profile of cardiac autonomic nervous modulation in healthy subjects: Differing Effects of aging and Gender on heart rate variability. J Cardiovasc Electrophysiol 14:8791–799

Bracic M, Stefanovska A (1998) Wavelet-based analysis of human blood-flow dynamics. Bull Math Biol 60:919–935

Broadman A, Schlindwein FS, Rocha AP, Leite A (2002) A study on the optimum order of autoregressive models for heart rate variability. Physiol Meas 23:324–36

Bušek P, Vaòková J, Opavský J, Salinger J, Nevšímalová S (2005) Spectral analysis of heart rate variability in sleep. Physiol Res 54:369–376

Carney RM, Blumenthal JA, Stein PK, Watkins L, Catellier D, Berkman LF, Czajkowski SM, O’Connor C, Stone PH, Freedland KE (2001) Depression, heart rate variability, and acute myocardial infarction. Circulation 104:2024

Carney RM, Blumenthal JA, Freedland KE, Stein PK, Howells WB, Berkman LF, Watkins LL, Czajkowski SM, Hayano J, Domitrovich PP, Jaffe AS (2005) Low heart rate variability and the effect of depression on post—myocardial infarction mortality. Arch Intern Med 165:1486–1491

Censi F, Calcagnini G, Cerutti S (2002) Coupling patterns between spontaneous rhythms and respiration in cardiovascular variability signals. Comput Meth Programs Biomed 68(1):37–47

Chandran V, Elgar S (1993) Pattern recognition using invariants defined from higher order spectra—one-dimensional inputs. IEEE Trans Signal Process 41:1

Chua KC, Chandran V, Acharya UR, Min LC (2006) Computer-based analysis of cardiac state using entropies, recurrence plots and Poincare geometry. J Med Eng Technol UK (in press)

Chui CK (1992) Wavelet analysis and its applications. Acadamic, Boston, MA

Cohen ME, Hudson DL, Deedwania PC (1996) Applying continuous chaotic modeling to cardiac signal analysis. IEEE Eng Med Biol 15:97–102

Coumel P, Hermida JS, Wennerblom B, Leenhardt A, Maison-Blanche P, Cauchemez B (1991) Heart rate variability in left ventricular hypertrophy and heart failure, and the effects of beta-blockade. Eur Heart J 12:412–422

Cysarz D, Bettermann H, van Leeuwen P (2000) Entropies of short binary sequences in heart period dynamics. Am J Physiol Heart Circ Physiol 278:H2163–H2172

Davy KP, Desouza CA, Jones PP, Seals DR (1998) Elevated heart rate variability in physically active young and older adult women. Clin Sci 94:579–584

Drinnan MJ, Allen J, Langley P, Murray A (2000) Detection of sleep apnoea from frequency analysis of heart rate variability. Comput Cardiol 27:259–62

Duru F, Candinas R, Dziekan G, Goebbels U, Myers J, Dubach P, Chur K (2000) Effect of exercise training on heart rate variability in patients with new-onset left ventricular dysfunction after myocardial infarction. Am Heart J 140(1):157–161

Eckmann JP, Kamphorst SO, Ruelle D (1987) Recurrence plots of dynamical systems. Europhys Lett 4:973–977

Elsenbrunch S, Harnish MJ, Orr WC (1999) Heart rate variability during waking and sleep in healthy males and females. Sleep 22(8):1067–1071

Emese N, Hajnalka O, Bardos G, Molnar P (2000) Gender-related heart rate differences in human neonates. Pediatr Res 47(6):778–780

Eryonucu B, Uzun K, Güler N, Bilge M (2001) Comparison of the acute effects of salbutamol and terbutaline on heart rate variability in adult asthmatic patients. Eur Respir J 17:863–867

Ewing DJ, Winney R (1975) Autonomic function in patients with chronic renal failure on intermittent haemodialysis. Nephron 15(6):424–429

Farrell TG, Bashir Y, Cripps T, Malik M, Poloniecki J, Bennett ED, Ward DE, Camm AJ (1991) Risk stratification for arrhythmic events in postinfarction patients based on heart rate variability, ambulatory electrocardiographic variables and the signal-averaged electrocardiogram. J Am Coll Cardiol 18:687–697

Fell J, Mann K, Roschke J, Gopinathan MS (2000) Nonlinear analysis of continuous ECG during sleep I. Reconstruction. Biol Cybernat 82:477–483

Finley JP, Nungent ST, Hellenbrand W (1987) Heart rate variability in children, spectral analysis of developmental changes between 5 and 25 years. Can J Physiol Pharmacol 65:2048–2052

Forsstrom J, Forsstrom J, Heinonen E, Valimaki I, Antila K (1986) Effects of haemodialysis on heart rate variability in chronic renal failure. Scand J Clin Lab Invest 46:665–670

Fraser AM (1989) Information and entropy in strange attractors. IEEE Trans Inform Theory 35:245–262

Fraser AM, Swinney HL (1986) Independent coordinates for strange attractors from mutual information. Phys Rev A 33:1134–1140

Gamero LG, Vila J, Palacios F (2002) Wavelet transform analysis of heart rate variability during myocardial ischaemia. Med Biol Eng Comput 40:72–78

Gates GJ, Mateika SE, Mateika JH (2005) Heart rate variability in non-apneic snorers and controls before and after continuous positive airway pressure. BMC Pulm Med 5:9

Ge D, Srinivasan N, Krishnan SM (2002) Cardiac arrhythmia classification using autoregressive modeling. BioMed Eng Online 1(1):5

Goldberger AL, West BJ (1987) Application of nonlinear dynamics to clinical cardiology. Ann NY Acad Sci 504:195–213

Grassberger P, Procassia I (1983) Measuring the strangeness of strange attractors. Physica D 9:189–208

Grossman P, Karemaker J, Wieling W (1991) Prediction of tonic parasympathetic cardiac control using respiratory sinus arrhythmia: the need for respiratory control. Psychophysiology 28:201–216

Grossmann A, Kronland-Martinet R, Morlet J (1989/1990) Reading and understanding continuous wavelet transforms. In: Combes JM, Grossmann A, Tchamitchian Ph (eds) Wavelets: time-frequency methods and phase space. Springer, Berlin Heidelberg New York, pp 2–20

Guzzetti S, Piccaluga E, Casati R, Cerutti S, Lombardi F, Pagani M et al (1988) Sympathetic predominance in essential hypertension: a study employing spectral analysis of heart rate variability. J Hypertens 6:711–717

Hayano J, Yamada M, Sakakibara Y et al (1990) short, longterm effects of cigarette smoking on heart rate variability. Am J Cardiol 65:84–88

Higuchi T (1988) Aproach to an irregular time series on the basis of the fractal theory. Physica D 31:277–283

Ho KK, Moody GB, Peng CK, Meitus JE, Larson MG, Levy D, Goldberger AL (1997) Predicting survival in heart failure case and control subjects by use of fully automated methods for deriving nonlinear and conventional indices of heart rate dynamics. Circulation 96:842–848

Huikuri HV, Makikallio TH, Peng CK, Goldberger AL, Hintze U, Moller M (2000) Fractal correlation properties of R–R interval dynamics and mortality in patients with depressed left ventricular function after an acute myocardial infarction. Circulation 101:47–53

Jamsek J, Stefanovska A, McClintock PVE (2004) Nonlinear cardio-respiratory interactions revealed by time-phase bispectral analysis. Phys Med Biol 49:4407–4425

Kamath MV, Fallen EL (1993) Power spectral analysis of heart rate variability: a noninvasive signature of cardiac autonomic function. Crit Rev Biomed Eng 21(3):245–311

Kamath MV, Fallen EL (1995) Correction of the heart rate vaiability signal for ectopics and missing beats. In: Malik M, Camm AJ (eds) Heart rate variability. Futura, Armonk, pp 75–85

Kamen PW, Krum H, Tonkin AM (1996) Poincare plot of heart rate variability allows quantitative display of parasympathetic nervous activity. Clin Sci 91:201–208

Kaplan DK, Cohen JR (1991) Searching for chaos in fibrillation. Ann NY Acad Sci 367–374

Katona PG, Jih F (1975) Respiratory sinus arrhythmia: noninvasive measure of parasympathetic cardiac control. J Appl Physiol 39:801–805

Katz MJ (1988) Fractals and analysis of waveforms. Comput Biol Med 18:145–156

Kleiger RE, Bigger JT, Bosner MS, Chung MK, Cook JR, Rolnitzky LM et al (1991) Stability over time of variables measuring heart rate variability in normal subjects. Am J Cardiol 68:626–630

Kobayashi M,Musha T (1982) 1/f fluctuation of heart beat period. IEEE Trans Biomed Eng 29:456–457

Kovatchev BP, Farhy LS, Cao H, Griffin MP, Lake DE, Moorman JR (2003) Sample asymmetry analysis of heart rate characteristics with application to neonatal sepsis and systemic inflammatory response syndrome. Pediatr Res 54:892–898

Laude D, Elghozi JL, Girald A, Bellard E, Bouhaddi M, Castiglioni P et al (2004) Comparison of various techniques used to estimate spontaneous baroreflex sensitivity (the EUROVAR study). Am J Physiol Regul Integr Comp Physiol 286:R226–R231

Leipzig TJ, Lowensohn RI (1986) Heart rate variability in neurosurgical patients. Neurosurgery 19:356–362

Lerma C, Minzoni A, Infante O, José MV (2004) A mathematical analysis for the cardiovascular control adaptations in chronic renal failure. Artif Organs 28(4):398–409

Levy MN,Schwartz PJ (eds) (1994) Vagal control of the heart: experimental basis and clinical implications. Future, Armonk

Lipsitz LA, Mietus J, Moody GB, Goldberger AL (1990) Spectral characteristics of heart rate variability before and during postural tilt: relations to aging and risk of syncope. Circulation 81:1803–1810

Lowensohn RI, Weiss M, Hon EH (1977) Heart-rate variability in brain-damaged adults. Lancet 1:626–628

Luchini D, Bertocchi F, Maliani A et al. (1996) A controlled study of the autonomic changes produced by habitual cigarette smoking in healthy subjects. Cardiovasc Res 31:633–639

Mager DE, Merritt MM, Kasturi J, Witkin LR, Urdiqui-Macdonald M, Sollers JJ III, Evans MK, Zonderman AB, Abernethy DR, Thayer JF (2004) Kullback–Leibler clustering of continuous wavelet transform measures of heart rate variability. Biomed Sci Instrum 40:337–342

Malik M, Farrell T, Cripps TR, Camm AJ (1989) Heart rate variability in relation to prognosis after myocardial infarction: selection of optimal processing techniques. Eur Heart J 10:1060–1074

Malliani A, Pagani M, Lombardi F, Cerutti S (1991) Cardiovascular neural regulation explored in the frequency domain. Circulation 84:482–92

Malpas SC, Whiteside EA, Maling TJ (1991) Heart rate variability and cardiac autonomic function in men with chronic alcohol dependence. Br Heart J 65:84–88

Mandelbrot BB (1983) Geometry of nature. Freeman, Sanfrancisco

Marwan N, Wessel N, Meyerfeldt U, Schirdewan A, Kurths J (2002) Recurrence-plot-based measures of complexity and their application to heart-rate-variability data. Phys Rev E 66(2)

Muller JE, Morrison J, Stone PH, Rude RE, Rosner B, Roberts R et al (1984) Nifedipine therapy for patients with threatened and acute myocardial infarction: a randomized, double-blind, placebo-controlled comparison. Circulation 69:740–747

Nagy E, Orvos H, Bardos G, Molnar P (2000) Gender- related heart rate differences in human neonates. Pediatr Res 47(6):778–780

Narayana Dutt D, Krishnan SM (1999) Application of phase space techniques to the analysis of cardiac signals. Proceedings of IEEE EMBS conference, Atlanta, USA

Ng TT, Chang SF, Sun Q (2004) Blind detection of photomontage using higher order statistics. In: IEEE international symposium on circuits and systems (ISCAS), Vancouver, Canada

Niedermaier O, Smith M, Beightol L et al (1993) Influence of cigarette smoking on human autonomic function. Circulation 88:562–571

Nikias CL, Rughuveer MR (1987) Bispectrum estimation: a digital signal processing framework. Proc IEEE 75:869–890

Oliver F, Acharya UR, Krishnan SM, Min LC (2004) Analysis of cardiovascular signals using spatial filling index and time-frequency domain. Biomed Online J USA 3:30

Owis MI, Abou-Zied AH, Youssef ABM, Kadah YM (2002) Study of features on nonlinear dynamical modeling in ECG arrhythmia detection and classification. IEEE Trans Biomed Eng 49(7):733–736

Pagani M, Lombardi F, Guzzetti S et al (1986) Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympatho-vagal interaction in man and conscious dog. Circ Res 59:178–193

Pater C, Compagnone D, Luszick J, Verboom C-N (2003) Effect of Omacor on HRV parameters in patients with recent uncomplicated myocardial infarction—a randomized, parallel group, double-blind, placebo-controlled trial: study design. Curr Control Trials Cardiovasc Med 4(2)

Paul SA, James NW, Gareth RC, Petter AS, Colin ER (2002) Finding coordinated atrial activity during ventricular fibrillation using wavelet decomposition. IEEE Eng Med Biol Mag 21(1):58–61

Pellizzer AM, Kamen PW, Esler MD et al (2001) Comparative effects of mibefradil and nifedipine gastrointestinal transport system on autonomic function in patients with mild to moderate essential hypertension. J Hypertens 19:279–285

Peng CK, Havlin S, Hausdorf JM, Mietus JE, Stanley HE, Goldberger AL (1996) Fractal mechanisms and heart rate dynamics. J Electrocardiol 28(Suppl):59–64

Pfeifer MA, Cook D, Brodsky J, Tice D, Reenan A, Swedine S et al (1982) Quantitative evaluation of cardiac parasympathetic activity in normal and diabetic man. Diabetes 3:339–45

Pincus SM (1991) Approximate entropy as a measure of system complexity. Proc Natl Acad Sci USA 88:2297–2301

Pincus SM, Goldberger AL (1994) Physiological time-series analysis: what does regularity quantify? Am J Physiol 266:1643–1656

Pincus SM, Viscarello RR (1992) Approximate entropy: a regularity measure for heart rate analysis. Obstet Gynecol 79:249–55

Pinhas I, Toledo E, Aravot D, Akselrod S (2004) Bicoherence analysis of new cardiovasculr spectral components observed in heart-transplant patients: statistical approach for bicoherence thresholding. IEEE Trans Biomed Eng 51:1774–1783

Pomeranz B, Macaulay RJB, Caudill MA, Kutz I, Adam D, Kilborn KM, Barger AC, Shannon DC, Cohen RJ, Benson H (1985) Assessment of autonomic function in humans by heart rate spectral analysis. Am J Physiol 248:H151–H153

Pope CA III, Eatough DJ, Gold DR, Pang Y, Nielsen KR, Nath P, Verrier RL, Kanner RE (2001) Acute exposure to environmental tobacco smoke and heart rate variability. Environ Health Perspect 109(7):711–716

Radhakrishna Rao KA, Vikram Kumar Yergani, Narayana Dutt D, Vedavathy TS (2001) Characterizing chaos in heart rate variability time series of panic disorder patients. In: Proceedings of ICBME Biovision. Bangalore, India, pp 163–167

Ramaekers D, Ector H, Aubert AE, Rubens A, van de Werf F (1993) Heart rate variability and heart rate in healthy volunteers: Is the female autonomous nervous system cardioprotective? Eur Heart J 19:1334–1341

Rao RM, Bopardikar AS (1998) Wavelet transforms introduction to theory and applications. Addison Wesley, Longman Inc, Reading, MA

Richman JS, Moorman JR (2000) Physiological time-series analysis using approximate entropy and sample entropy. Am J Physiol Heart Circ Physiol 278:H2039–H2049

Richman JS, Randall MJ (2000) Physiological time-series analysis using approximate entropy and sample entropy. Am J Physiol Heart Circ Physiol 278:H2039–H2049

Roche F, Pichot V, Sforza E, Court-Fortune I, Duverney D, Costes F, Garet M, Barthélémy J-C (2003) Predicting sleep apnoea syndrome from heart period: a time-frequency wavelet analysis. Eur Respir J 22:937–942

Rosenstien M, Colins JJ, De Luca CJ (1993) A practical method for calculating largest Lyapunov exponents from small data sets. Physica D 65:117–134

Rossinin J, Vitasalo M, Partanen J et al (1997) Effects of acute alcohol ingestion on heart rate variability in patients with documented coronary artery disease and stable angina pectoris. Am J Cardiol 79:487–491

Rother M, Zwiener U, Witte H, Eiselt M, Frenzel J (1988) Objective characterization and differentiation of sleep states in healthy newborns and newborns-at-risk by spectral analysis of heart rate and respiration rhythms. Acta Physiol Hung 71:383–393

Rothschild M, Rothschild A, Pfeifer M (1988) Temporary decrease in cardiac parasympathetic tone after acute myocardial infarction. Am J Cardiol 18:637–639

Ryan JM, Howes LG (2000) White coat effect of alcohol. Am J Hypertens, 13:1135–1138

Ryan SM, Goldberger AL, Pincus SM, Mietus J, Lipsitz LA (1994) Gender-and age-related differences in heart rate: are women more complex than men. J Am Coll Cardiol 24(7):1700–1707

Saul JP (1990) Beat-to-beat variations of heart rate reflect modulation of cardiac autonomic outflow. News Physiol Sci 5:32–37

Saul J, Rea R, Eckberg D, Berger R, Cohen R (1990) Heart rate and muscle sympathetic nerve variability during reflex changes of autonomic activity. Am J Physiol 258:H713–H721

Sayar K, Güleç H, Gökçe M, Ak I (2002) Heart rate variability in depressed patients. Bull Clin Psychopharmacol 12(3):130–133

Schumacher A (2004) Linear and nonlinear approaches to the analysis of R–R interval variability. Biol Res Nurs 5(3):211–221

Schwartz PJ, Priori SG (1990) Sympathetic nervous system and cardiac arrythmias. In: Zipes DP, Jalife J (eds) Cardiac electrophysiology. From cell to bedside. W.B. Saunders, Philadelphia, pp 330–343

Schwartz JB, Gibb WJ, Tran T (1991) Aging effects on heart rate variation. J Gerontol 46:M99–M106

Schwartz PJ, La Rovere MT, Vanoli E (1992) Autonomic nervous system and sudden cardiac death. Experimental basis and clinical observations for post-myocardial infarction risk stratification. Circulation 85(Suppl I):I77–I91

Shimojima H, Tsutsumi T, Yanagisawa F, Komukai M, Zenda N, Higashi Y, Takeyama Y, Okamoto Y (2003) Application of wavelet transform for analysis of QRS complex in intraventricular conduction abnormalities. Int J Bioelectromagn 5(1):279–281

Singh JP, Larson MG, O’Donell CJ, Wilson PF, Tsuji H, Lyod-Jones DM, Levy D (2000) Association of hyperglycemia with reduced heart rate variability: the Framingham heart study. Am J Cardiol 86:309–312

Task Force of the European Society of Cardiology and North American Society of Pacing and Electrophysiology (1996) Heart rate variability: standards of measurement, physiological interpretation and clinical use. Eur Heart J 17:354–381

Theiler J, Eubank S, Longtin A, Galdrikian B, Farmer JD (1992) Testing for nonlinearity in time series: the method of surrogate data. Physica D 58:77–94

Togo F, Yamamoto Y (2000) Decreased fractal component of human heart rate variability during non-REM sleep. Am J Physiol Heart Circ Physiol 280:H17–H21

Toledo E, Gurevitz O, Hod H, Eldar M, Akselrod S (2003) Wavelet analysis of instantaneous heart rate: a study of autonomic control during thrombolysis. Am J Physiol Regul Integr Comp Physiol 284(4):R1079–R1091

Tsai AC, Chiu HW (2002) Relationship between heart rate variability and electrolyte concentration in chronic renal failure patients under hemodialysis. Int J Bioelectromagn 4(2):307–308

Tulen JH, Boomsma F, Man in t’veld AJ (1999) Cardiovascular control and plasma catecholamines during restand mental stress: effects of posture. Clin Sc 96:567–576

Tulppo MP, Makikallio TH, Takala TES, Seppanen T, Huikuri HV (1996) Quantitative beat-to-beat analysis of heart rate dynamics during exercise. Am J Physiol 271:H244–H252

Van Geijn HP, Jongsma HW, de Haan J, Eskes TK, Prechtl HF (1980) Heart rate as an indicator of the behavioral state. Am J Obstet Gynecol 136:1061–1066

Van Ravenswaaij CM, Hopman JC, Kollee LA, Van Amen JP, Stoelinga GB, Van Geijn HP (1991) Influences on heart rate variability in spontaneously breathing preterm infants. Early Hum Dev 27:187–205

Verlinde D, Beckers F, Ramaekers D, Aubert AE (2001) Wavelet decomposition analysis of heart rate variability in aerobic athletes. Auton Neurosci 90(1–2):138–141

Vetterli M (1992) Wavelet and filter banks: theory and design. IEEE Trans Signal Process 40(9):2207–2232

Vetterli M, Kovacevic J (1995) Wavelets and subband coding. Prentice-Hall, Englewood Cliffs, NJ

Viktor A, Jurij-MAtija K, Roman T et al (2003) Breathing rates and heart rate spectrograms regarding body position in normal subjects. Comput Biol Med 33:259–266

Villa MP, Calcagnini G, Pagani J, Paggi B, Massa F, Ronchetti R (2000) Effects of sleep stage and age on short-term heart rate variability during sleep in healthy infants and children. Chest 117:460–466

Villareal RP, Liu BC, Massumi A (2002) Heart rate variability and cardiovascular mortality. Curr Atheroscler Rep 4(2):120–127

Weise F, Heydenreich F, Kropf S, Krell D (1990) Intercorrelation analyses among age, spectral parameters of heart rate variability and respiration in human volunteers. J Interdiscipl Cycle Res 21:17–24

West BJ (2000) Fractal physiology and medicine: studies of nonlinear phenomena in life. Science 1. World Scientific, Singapore

Westerhof BE, Gisolf J, Stok WJ, Wesseling KH, Karemaker JM (2004) Time-domain cross-correlation baroreflex sensitivity: performance on the EUROBAVAR data set. J Hypertens 22(7):1259–1263

Wharton JM, Coleman RE, Strauss HC (1992) The role of the autonomic nervous system in sudden cardiac death. Trends Cardiovasc Med 2:65–71

Wheeler T, Watkins PJ (1973) Cardiac denervation in diabetes. Br Med J 4:584–586

Wilson PW, Evans JC (1993) Coronary artery prediction. Am J Hypertens 6:309S–313S

Witte H, Putsche P, Eiselt M, Arnold M, Schmidt K (2001) Technique for the quantification of transient quadratic phase couplings between heart rate components. Biomed Tech (Berl) 46:42–49

Wolf A, Swift JB, Swinney HL, Vastano JA (1985) Determining Lyapunov exponents from a time series. Physica D 16:285–317

Woo MA, Stevenson WG, Moser DK, Trelease RB, Harper RH (1992) Patterns of beat-to-beat heart rate variability in advanced heart failure. Am Heart J 123:704–707

Yamasaki Y, Kodama M, Matsuhisa M (1996) Diurnal heart rate variability in healthy subjects: effects of aging and sex differences. Am J Physiol 271:303–310

Zeskind PS, Gingras JL (2006) Maternal cigarette-smoking during pregnancy disrupts rhythms in fetal heart rate. J Pediatr Psychol 31(1):5–14

Zoccali C, Ciccarelli M, Maggiore Q (1982) Defective reflex control of heart rate in dialysis patients: evidence for an afferent autonomic lesion. Clin Sci 63:285–292