Abstract
We have determined if there are differences in normal subjects who fainted and those who did not faint during prolonged standing. We studied the short-term orthostatic responses in relation to heart rate, blood pressure measured by Finapres, left ventricular stroke volume analysed by pulse contour method, cardiac output and systemic vascular resistance, and also postural blood pressure and heart rate variability as assessed by spectral analysis. Thirteen healthy males without a history of syncope were studied. Three fainted after 10–13 min standing; the ten non-fainters remained upright for 20 min. The initial (first 30 s) postural circulatory adjustment was comparable for blood pressure but the rebound bradycardia was smaller in the fainters (heart rate at 22 s amounted to +13 ±10 beats/min above control vs. +1 ±5 beats/min in the non-fainters). Upright heart rate at 2 min standing was higher in the fainters (+31 ±2 beats/min vs. +20 ±5 beats/min), and blood pressure at 7 min standing was lower (−2/+5/+8 ± 5/5/5 mmHg vs. +11/+13/+16 ± 10/6/5 mmHg). The responses of stroke volume and cardiac output were comparable but systemic vascular resistance gradually decreased in the fainters from 5 min standing to the onset of fainting (+4 ±13% vs. +33 ±19% at 7 min standing). In fainters, the variability in upright blood pressure around 0.1 Hz was larger (8.8 mmHg2/Hz for diastolic blood pressure vs. 5.7 ±1.5 mmHg2/Hz in non-fainters).
In conclusion, the circulatory adjustments to active standing in fainters is different from non-fainters, as they lose vasoconstrictor tone after 5 min of standing despite an increase in blood pressure variability and heart rate which suggest increased sympathetic activity. Whether there are other opposing factors, which include vasodilator substances, is discussed.
Similar content being viewed by others
References
Fitzpatrick AP, Theodorakis G, Vardas P, Sutton R. Methodology of heat-up tilt testing in patients with unexplained syncope.J Am Coll Cardiol 1991;17: 125–130.
Kapoor WN, Brant N. Evaluation of syncope by upright tilt testing with isoproterenol: a nonspecific test.Ann Int Med 1992;116: 358–363.
Ten Harkel ADJ, Van Lieshout JJ, Van Lieshout EJ, Wieling W. Assessment of cardiovascular reflex tests: influence of posture and period of preceding rest.J Appl Physiol 1990;68: 147–153.
Lipsitz LA, Mietus J, Moody GB, Goldberger AL. Spectral characteristics of heart rate variability before and during postural tilt. Relation to age and risk of syncope.Circulation 1990;81: 1803–1810.
Ten Harkel ADJ, Baisch F, Beck L, Karemaker JM. The autonomic nervous system in blood pressure regulation during 10 days 6° head down tilt.Physiologist 1990;33 (suppl): S178-S179.
Wesseling KH, De Wit B, Weber JAP, Smith NT. A simple device for the continuous measurement of cardiac output.Adv Cardiovasc Phys 1983;511: 16–52.
Wieling W, Veerman DP, Dambrink JHA, Imholz BPM. Disparities in circulatory adaptation upon standing between young and old subjects explained by pulse contour analysis.Clin Sci 1992;83: 149–155.
Wieling W, Ten Harkel ADJ, Van Lieshout JJ. Spectrum of orthostatic disorders: classification based on an analysis of the short-term circulatory response upon standing.Clin Sci 1991;81: 241–248.
Wesseling KH, De Wit B, Settels JJ, Klawer WH. On the indirect registration of finger blood pressure after Peñáz.Funktionelle Biologische Medizin 1982;1: 245–250.
Wesseling KH, Settels JJ, De Wit B. The measurement of continuous finger arterial pressure noninvasively in stationary subjects. In: Schmidt TH, Dembroski TM, Bluemchen G, eds.Biological and Psychological Factors in Cardiovascular Disease. Berlin: Springer-Verlag, 1986: 355–375.
Wesseling KH. Finapres, continuous noninvasive finger arterial pressure based on the method of Peñáz. In: Meyer-Sabellek W, Anlauf M, Gotzen R, Steinfeld L, eds.Blood Pressure Measurements. Darmstadt: Steinkopf Verlag, 1990: 161–172.
Imholz BPM, Settels JJ, Van den Meiracker AH, Wesseling KH, Wieling W. Noninvasive beat to beat finger bloodpressure measurement during orthostatic stress compared to intraarterial pressure.Cardiovasc Res 1990;24: 214–221.
Wesseling KH, Settels JJ, Van der Hoeven GMA, Nijboer JA, Butijn MWT, Dorlas JC. Effects of peripheral vasoconstriction on the measurement of bloodpressure in a finger.Cardiovasc Res 1985;19: 139–145.
Bevington PR.Data Reduction and Error Analysis for the Physical Sciences. New York: McGraw-Hill, 1969.
Toorop GP, Westerhof N, Elzinga G. Beat-to-beat estimation of peripheral resistance and arterial compliance during pressure transients.Am J Physiol 1987;252: H1275-H1283.
Imholz BPM, Parati G, Mancia G, Wesseling KH. Effects of graded vasoconstriction on the measurement of finger arterial pressure.J Hypertension 1992;10: 979–984.
Jansen JRC, Wesseling KH, Settels JJ, Schreuder JJ. Continuous cardiac output monitoring by pulse contour during cardiac surgery.Eur Heart J 1990;11 (suppl 1): 26–32.
Stok WJ, Baisch F, Hillebrecht A, Schulz H, Karemaker JM. Noninvasive cardiac output measurement by arterial pulse analysis compared to inert gas rebreathing.J Appl Physiol 1993; in press.
De Boer RW, Karemaker JM, Strackee J. Hemodynamic fluctuations and baroreflex sensitivity in humans: a beat-to-beat model.Am J Physiol 1987;253: H680-H689.
Wieling W. Non-invasive recording of heart rate and blood pressure in the evaluation of neurocardiovascular control. In: Bannister R, Mathias CJ, eds.Autonomic failure, a textbook of clinical disorders of the autonomic nervous system. Oxford: Oxford University Press, 1992: 291–311.
Van Lieshout JJ, Wieling W, Karemaker JM, Eckberg DL. The vasovagal response.Clin Sci 1991;81: 575–586.
Dambrink JHA, Imholz BPM, Karemaker JM, Wieling W. Circulatory adaptation to orthostatic stress in healthy 10–14 year old children investigated in a general practice.Clin Sci 1991;81: 51–58.
Streeten DHP. In:Orthostatic Disorders of the Circulation. Mechanisms, Manifestations and Treatment. New York: Plenum Medical Book Company, 1986: 127–172.
Ten Harkel ADJ, Baisch F, Karemaker JM. Increased orthostatic blood pressure variability after prolonged head down tilt.Acta Physiol Scand 1992;144 (S604): 89–99.
Burke D, Sundlof G, Wallin G. Postural effects on muscle nerve sympathetic activity in man.J Physiol 1977;272: 399–414.
Ebert TJ, Danahan T. Hemodynamic responses of high-fit runners during head-up tilt testing to syncope.Physiologist 1992;35 (abstract): 237.
Shepherd JT, Vanhoutte PM.The Human Cardiovascular System. Facts and Concepts. New York: Raven Press, 1979.
Rowell LB, Seals DR. Sympathetic activity during graded central hypovolemia in hypoxemic humans.Am J Physiol 1990;259: H1197-H1206.
Van Lieshout JJ, Ten Harkel ADJ, Van Leeuwen AM, Wieling W. Contrasting effects of acute and chronic volume expansion on orthostatic blood pressure control in a patient with autonomic circulatory failure.Netherlands J Med 1991;39: 72–83.
Ruetz PP, Johnson SA, Callahan R, Meade RC, Smith JJ. Fainting: a review of its mechanism and a study in blood donors.Medicine 1967;46: 363–384.
Bergenwald L, Freyschuss U, Sjostrand T. The mechanism of orthostatic and haemorrhagic fainting.J Clin Lab Invest 1977;37: 209–216.
Sander-Jensen K, Mehlsen J, Secher NH, Bach FW, Bie P, Giese J, Schwarz TW, Trap-Jensen J, Warberg J. Progressive central hypovolaemia in man—resulting in a vasovagal syncope? Haemodynamic and endocrine variables during venous tourniquets of the thighs.Clin Physiol 1987;7: 231–242.
Grubb BP, Gerard G, Roush K, Temesy-Armos P, Montford P, Elliott L, Hahn H, Brewster P. Cerebral vasoconstriction during head-upright tilt-induced vasovagal syncope. A paradoxic and unexpected response.Circulation 1991;84: 1157–1164.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
ten Harkel, A.D.J., van Lieshout, J.J., Karemaker, J.M. et al. Differences in circulatory control in normal subjects who faint and who do not faint during orthostatic stress. Clinical Autonomic Research 3, 117–124 (1993). https://doi.org/10.1007/BF01818996
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01818996