Time and frequency domain analyses of heart rate variability during orthostatic stress in patients with neurally mediated syncope.

The role of autonomic balance during upright tilt in patients with neurally mediated syncope is unclear. To assess the characteristics of autonomic tone during orthostatic stress, 15 patients (mean age 32 years) with recurrent episodes of syncope (> or = 2) and a positive response to a 30-minute 60 degrees upright tilt were compared with the following control groups: (1) 15 patients (mean age 33.5 years) with > or = 2 episodes of recurrent syncope and a negative tilt response, and (2) 15 age- and sex-matched healthy volunteers (mean age 34 years) with no previous history of presyncope or syncope. Time domain measurements assessed were mean RR interval, standard deviation of normal RR intervals, and percentage of normal consecutive RR intervals differing by > 50 ms. Frequency domain measurements of the low-frequency (LF) and high-frequency (HF) bands were obtained, and the LF/HF ratio was also calculated. All variables were calculated in the supine position and during the first 5 minutes of upright tilt. No significant difference was observed in the time and frequency domain variables in the supine position between control groups with a negative head-up tilt response and the group with a positive response. The percentage of normal consecutive RR intervals differing by > 50 ms during the first 5 minutes of head-up tilt was significantly higher in the group with positive tilt tests than in the controls (25 +/- 12% vs 7 +/- 4%, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[1]  R. Rea Neurally mediated hypotension and bradycardia: which nerves? How mediated? , 1989, Journal of the American College of Cardiology.

[2]  S Cerutti,et al.  Heart rate variability as an index of sympathovagal interaction after acute myocardial infarction. , 1987, The American journal of cardiology.

[3]  D. Adam,et al.  Assessment of autonomic function in humans by heart rate spectral analysis. , 1985, The American journal of physiology.

[4]  J Strackee,et al.  Hemodynamic fluctuations and baroreflex sensitivity in humans: a beat-to-beat model. , 1987, The American journal of physiology.

[5]  G. Moody,et al.  Spectral characteristics of heart rate variability before and during postural tilt. Relations to aging and risk of syncope. , 1990, Circulation.

[6]  A. Muir,et al.  Lack of variation in venous tone potentiates vasovagal syncope. , 1992, British heart journal.

[7]  J. Strasburger,et al.  Heart rate and blood pressure response to upright tilt in young patients with unexplained syncope. , 1990, Journal of the American College of Cardiology.

[8]  A. Malliani,et al.  Cardiovascular Neural Regulation Explored in the Frequency Domain , 1991, Circulation.

[9]  W E Boden,et al.  Effect of passive tilt on sympathetic and parasympathetic components of heart rate variability in normal subjects. , 1989, The American journal of cardiology.

[10]  D N Ghista,et al.  Power spectrum of heart rate variability: a non-invasive test of integrated neurocardiac function. , 1988, Clinical and investigative medicine. Medecine clinique et experimentale.

[11]  H. Robbe,et al.  Assessment of baroreceptor reflex sensitivity by means of spectral analysis. , 1987, Hypertension.

[12]  A. Mark The Bezold-Jarisch reflex revisited: clinical implications of inhibitory reflexes originating in the heart. , 1983, Journal of the American College of Cardiology.

[13]  C. Morillo,et al.  A placebo-controlled trial of intravenous and oral disopyramide for prevention of neurally mediated syncope induced by heap-up tilt , 1993 .

[14]  S Cerutti,et al.  Spectral and cross-spectral analysis of heart rate and arterial blood pressure variability signals. , 1986, Computers and biomedical research, an international journal.

[15]  A. Camm,et al.  Assessment of autonomic function in patients with neurally mediated syncope: augmented cardiopulmonary baroreceptor responses to graded orthostatic stress. , 1993, Journal of the American College of Cardiology.

[16]  D. Eckberg,et al.  Important influence of respiration on human R-R interval power spectra is largely ignored. , 1993, Journal of applied physiology.

[17]  F. Fouad-Tarazi,et al.  The Usefulness of Head‐Up Tilt Testing and Hemodynamic Investigations in the Workup of Syncope of Unknown Origin , 1988, Pacing and clinical electrophysiology : PACE.

[18]  P. Toutouzas,et al.  Heart Rate Variability in Patients with Vasovagal Syndrome , 1992, Pacing and clinical electrophysiology : PACE.

[19]  R. Cohen,et al.  Hemodynamic regulation: investigation by spectral analysis. , 1985, The American journal of physiology.

[20]  Abboud Fm Ventricular syncope: is the heart a sensory organ? , 1989 .

[21]  B. Wallin,et al.  Sympathetic outflow to muscles during vasovagal syncope. , 1982, Journal of the autonomic nervous system.

[22]  J. Jalonen,et al.  Effect of posture on spontaneous and thermally stimulated cardiovascular oscillations. , 1990, Cardiovascular research.

[23]  P. Thorén,et al.  Increased activity in left ventricular receptors during hemorrhage or occlusion of caval veins in the cat. A possible cause of the vaso-vagal reaction. , 1972, Acta physiologica Scandinavica.

[24]  A. Camm,et al.  Impaired immediate vasoconstrictor responses in patients with recurrent neurally mediated syncope. , 1993, The American journal of cardiology.

[25]  M. Turiel,et al.  Power Spectral Analysis of Heart Rate and Arterial Pressure Variabilities as a Marker of Sympatho‐Vagal Interaction in Man and Conscious Dog , 1986, Circulation research.