This Article Full Text Full Text (PDF) Correction (v112,pe122) All Versions of this Article: 112/4/465    most recent CIRCULATIONAHA.104.518449v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Guzzetti, S. Articles by Porta, A. Search for Related Content PubMed PubMed Citation Articles by Guzzetti, S. Articles by Porta, A. Related Collections Electrocardiology Autonomic, reflex, and neurohumoral control of circulation Arrythmias-basic studies

(Circulation. 2005;112:465-470.)
© 2005 American Heart Association, Inc.

Arrhythmia/Electrophysiology

Symbolic Dynamics of Heart Rate Variability

A Probe to Investigate Cardiac Autonomic Modulation

Stefano Guzzetti, MD; Ester Borroni, MD; Pietro E. Garbelli, MD; Elisa Ceriani, MD; Paolo Della Bella, MD; Nicola Montano, MD; Chiara Cogliati, MD; Virend K. Somers, MD; Alberto Mallani, MD; Alberto Porta, PhD

From Medicina Interna II and Dipartimento Scienze Cliniche, Ospedale "Luigi Sacco" (S.G., E.B., P.E.G., E.C., N.M., C.C., A.M.), and Dipartimento Scienze Precliniche, LITA di Vialba (A.P.), Universita’ degli Studi di Milano, Milano, Italy; Centro Cardiologico, Fondazione Monzino, Milano, Italy (P.D.B.); and Division of Cardiovascular Disease, Mayo Clinic College of Medicine, Rochester, Minn (V.K.S.).

Correspondence to Dr Stefano Guzzetti, Medicina Interna II, Ospedale "L. Sacco," Via GB Grassi 74, 20157 Milano, Italy. E-mail stefanog{at}fisiopat.sacco.unimi.it

Received November 3, 2004; revision received April 8, 2005; accepted April 12, 2005.

Background— Sympathetic and parasympathetic systems are considered the principal rapidly reacting systems that control heart rate.

Methods and Results— We propose a symbolic analysis series to quantify the prevalence of sympathetic or parasympathetic cardiac modulation. This analysis decomposes the heart rate variability series in patterns lasting 3 beats and classifies them into 3 categories: nonvariable, variable, and very variable patterns referred to as 0V, 1V, and 2V patterns. First, we applied this method to experimental and pharmacological conditions characterized by sympathetic activation (tilt test, handgrip, nitroprusside, and high-dose atropine administration) or parasympathetic activation (phenylephrine and low-dose atropine administration) in 60 healthy subjects. An increase in sympathetic modulation and a vagal withdrawal elicited a significant increase in 0V patterns and a decrease in 2V patterns, whereas parasympathetic dominance induced the opposite, reflecting a reciprocal sympathovagal balance. The second part of the study considered a series of 300 beats before the onset of major arrhythmic events in patients with an implantable cardioverter-defibrillator. Symbolic analysis detected an increase in the percentage of 0V patterns before the onset of major arrhythmias compared with baseline (41.6±3.9% and 24.4±2.9%, respectively; P<0.01), indicating a sympathetic prevalence. On the other hand, the 2V patterns did not decrease before major arrhythmias, suggesting the presence of nonreciprocal autonomic modulations.

Conclusions— Symbolic analysis of 3 beat sequences takes into account the different time course of sympathetic and parasympathetic cardiac modulations and seems appropriate for elucidating the neural pathophysiological mechanisms occurring during the short periods that precede acute cardiac events.

---

 

CLINICAL PERSPECTIVE

This article has been cited by other articles:

				V. R. S. Fernandes, K. C. Wu, B. D. Rosen, A. Schmidt, A. C. Lardo, N. Osman, H. R. Halperin, G. Tomaselli, R. Berger, D. A. Bluemke, et al. Enhanced Infarct Border Zone Function and Altered Mechanical Activation Predict Inducibility of Monomorphic Ventricular Tachycardia in Patients with Ischemic Cardiomyopathy Radiology, December 1, 2007; 245(3): 712 - 719. [Abstract] [Full Text] [PDF]

				A. Porta, E. Tobaldini, S. Guzzetti, R. Furlan, N. Montano, and T. Gnecchi-Ruscone Assessment of cardiac autonomic modulation during graded head-up tilt by symbolic analysis of heart rate variability Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H702 - H708. [Abstract] [Full Text] [PDF]