Effect of postural changes on arterial baroreflex sensitivity assessed by the spontaneous sequence method and Valsalva manoeuvre in healthy subjects
- 260 Downloads
The objective of this study was to compare the baroreflex sensitivity (BRS) assessed by the new, non-invasive, spontaneous sequence method (BRS-sequence) with the Valsalva manoeuvrebased BRS. Fourteen healthy volunteers were studied in the supine position, during 60° head-up tilt (HUT) and during −30° head-down tilt (HDT). Blood pressure and R-R intervals were continuously and non-invasively recorded using a Finapres device. The BRS-sequence was assessed by analysing the slopes of spontaneously occurring sequences of three or more consecutive beats in which systolic blood pressure and R-R interval of the following beat increased or decreased in the same direction in a linear fashion; it was compared with data obtained during the Valsalva manoeuvre in each position. The time and frequency domain indices of R-R interval variability were also evaluated. The mean difference of BRS between the two non-invasive methods was 3.86 ms/mmHg with a standard deviation of 9.14 ms/mmHg. BRS was decreased during HUT and increased during HDT as assessed by both techniques. The changes in BRS were associated with vagal withdrawal and sympathetic activation during HUT and enhancement in the cardiac vagal tone and reduction in the sympathetic activity during HDT. We conclude that the BRS-sequence technique provides a reliable method to study the neural control of the circulation, although the body position in consecutive measurements needs to be standardized.
Keywordsarterial baroreflexes posture non-invasive measurements
Unable to display preview. Download preview PDF.
- 2.Mancia G, Ferrari AU, Zanchetti A. Reflex control of the circulation in experimental and human hypertension. In: Zanchetti A, Tarazi RC, eds.Handbook of Hypertension. Volume 8. Pathophysiology of Hypertension: Regulatory Mechanisms. Amsterdam: Elsevier, 1986; 47–68.Google Scholar
- 9.Farell TG, Paul V, Cripps TRet al. Baroreflex sensitivity and electrophysiological correlates in patients after acute myocardial infarction.Circulation 1991;83: 945–952.Google Scholar
- 15.Wesseling KH, deWit B, Settels JJ, Klawer WH. On the indirect registration of finger blood pressure after Penaz.Funct Biol Med 1982;1: 245–250.Google Scholar
- 16.Kardos A, Gingl Z. Continuous non invasive on-line monitoring system for blood pressure and heart rate variability in humans.Cardiol Hung 1994;2: 39–51.Google Scholar
- 18.Bloomfield P.Fourier Analysis of Time Series: An Introduction. New York: John Wiley, 1976.Google Scholar
- 19.Pagani M, Lombardi F, Guzzetti Set al. Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympathovagal interaction in man and conscious dog.Circ Res 1986;56: 178–193.Google Scholar
- 20.Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement.Lancet 1986;i:307–310.Google Scholar
- 24.Tomomatsu E, Nishi K. Increased activity of carotid sinus baroreceptors by sympathetic stimulation and norepinephrine.Am J Physiol 1981;240: 650–658.Google Scholar
- 28.Palmero HA, Caeiro TF, Iosa DJ, Bas J. Baroreceptor reflex sensitivity derived from phase 4 of the Valsalva maneuver.Hypertension 1981;3 (suppl. II): 134–137.Google Scholar
- 32.Gingl Z, Rudas L, Kardos A. Effects of electrical artifacts and extrasystolic arrhythmia on the linear and spectral markers of the spontaneous baroreflex sensitivity.Cardiol Hung 1996; suppl. 2: 29.Google Scholar