From the Hebrew Rehabilitation Center for Aged Research and Training
Institute (L.A.L., R.J.M.), the Beth Israel/Deaconess Medical Center
Department of Medicine, Harvard Medical School, Boston, Mass (L.A.L.); and
Nagoya City University Medical School, Nagoya, Japan (J.H., S.S., A.O.).
Correspondence to Lewis A. Lipsitz, MD, Hebrew Rehabilitation Center for Aged, 1200 Centre St, Boston, MA 02131. E-mail Lipsitz{at}mail.hrca.harvard.edu
Background—The dynamic autonomic
processes leading to vasovagal syncope are poorly understood.
Methods and Results—We used complex demodulation to continuously
assess changes in respiration, R-R interval, and arterial
pressure (blood pressure) variability during 60 degree head-up tilt in
25 healthy subjects with tilt-induced vasovagal syncope and 25
age-matched nonsyncopal control subjects. Coherence and transfer
function analyses were used to examine the relation between
respiration and R-R interval variability before syncope. Baseline blood
pressure, R-R, and ventilation were similar between syncope subjects
and control subjects. Syncope subjects experienced an increase in tidal
volume and decrease in BP beginning 3 minutes before impending syncope
(systolic blood pressure <80 mm Hg) necessitated
termination of tilt. Approximately 90 seconds before syncope there was
a sudden prolongation of R-R interval and increase in amplitude of high
and low frequency R-R interval variability, indicating an abrupt
enhancement of vagal tone. The increase in respiratory amplitude
between 180 and 90 seconds before syncope was not accompanied by
changes in R-R interval or R-R variability, suggesting a dissociation
between respiration and the respiratory sinus arrhythmia. The
coherence analysis showed fewer syncope subjects with coherence
between respiratory and R-R interval variabilities and lower transfer
magnitudes in syncope subjects compared with control subjects.
Nonsyncopal subjects had no change in respiratory, R-R interval, or
blood pressure dynamics during matched time periods before the time of
syncope.
Conclusions—Vasovagal syncope is preceded by a period of
hyperpnea and cardiorespiratory decoupling followed by an abrupt
increase in cardiovagal tone. Respiratory pumping without inspiratory
cardiac slowing may partially counteract preload reduction until sudden
bradycardia precipitates syncope.
© 1998 American Heart Association, Inc.
Clinical Investigation and Reports
Complex Demodulation of Cardiorespiratory Dynamics Preceding Vasovagal Syncope
Key Words: respiration • heart rate • Fourier analysis
This article has been cited by other articles:
 |
|
 |
|
  A. Kamiya, J. Hayano, T. Kawada, D. Michikami, K. Yamamoto, H. Ariumi, S. Shimizu, K. Uemura, T. Miyamoto, T. Aiba, et al. Low-frequency oscillation of sympathetic nerve activity decreases during development of tilt-induced syncope preceding sympathetic withdrawal and bradycardia Am J Physiol Heart Circ Physiol, October 1, 2005; 289(4): H1758 - H1769. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Grossman, F. H. Wilhelm, and M. Spoerle Respiratory sinus arrhythmia, cardiac vagal control, and daily activity Am J Physiol Heart Circ Physiol, August 1, 2004; 287(2): H728 - H734. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. D. Giardino, R. W. Glenny, S. Borson, and L. Chan Respiratory sinus arrhythmia is associated with efficiency of pulmonary gas exchange in healthy humans Am J Physiol Heart Circ Physiol, May 1, 2003; 284(5): H1585 - H1591. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L Bernardi, C Passino, C Porta, E Anesi, G Palladini, and G Merlini Widespread cardiovascular autonomic dysfunction in primary amyloidosis: does spontaneous hyperventilation have a compensatory role against postural hypotension? Heart, December 1, 2002; 88(6): 615 - 621. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Alboni, M. Dinelli, P. Gruppillo, M. Bondanelli, K. Bettiol, P. Marchi, and E. C. d. Uberti Haemodynamic changes early in prodromal symptoms of vasovagal syncope Europace, January 1, 2002; 4(3): 333 - 338. [Abstract] [PDF]
|
|
|
|
 |
|
 A. Lagi, S. Cencetti, V. Corsoni, D. Georgiadis, and S. Bacalli Cerebral Vasoconstriction in Vasovagal Syncope: Any Link With Symptoms?: A Transcranial Doppler Study Circulation, November 27, 2001; 104(22): 2694 - 2698. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. M. Kinsella and J. P. Tuckey Perioperative bradycardia and asystole: relationship to vasovagal syncope and the Bezold-Jarisch reflex Br. J. Anaesth., June 1, 2001; 86(6): 859 - 868. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A S KURBAAN and R SUTTON Pacing for vasovagal syncope Heart, December 1, 1999; 82(6): 649 - 650. [Full Text]
|
|