© 2004 by European Society of Cardiology
EDITORIAL COMMENT
Editorial comment
Editor-in-Chief Royal Brompton and Harefield NHS Trust, Department of Cardiology Sydney Street, London SW3 6NP, United Kingdom
*Tel.: +44 207 351 8607; fax: +44 207 351 8625. E-mail address: europace.office{at}virgin.net
The paper by Giese et al. in this issue of Europace [1]
raises exciting issues for those concerned with the investigation and treatment of syncope. The authors point out that maintenance of consciousness depends on systemic arterial pressure being above the lower limit of cerebral blood flow autoregulation and, further, that this limit may be higher in those who are hypertensive. So they expected that tilt-induced syncope would occur at higher systemic arterial pressures in older subjects, as they would have higher baseline blood pressures. They excluded patients with previously known and treated hypertension. They confirmed their expectations that the older subjects had higher baseline systolic blood pressures but they could not demonstrate that these subjects had higher systolic pressures at syncope. In fact, blood pressure reserve tended to increase with increasing age, a finding that was statistically significant. Thus, the older patient can apparently sustain a greater blood pressure fall before syncope than the younger one. This had the predictable effect that older subjects became syncopal later in the tilt test (also statistically significant).
In general, older patients may tolerate tilt testing less well than younger individuals [2] from the comfort point of view which conflicts with their enhanced ability to tolerate the test on haemodynamic grounds [1].
A conclusion may be drawn that challenge with nitroglycerin sublingually or isoprenaline intravenously could be given earlier than the presently advocated 20 min [3]. This would be with the aim of maximizing the orthostatic challenge but in advance of discomfort which leads to fidgeting and reinstitution of the lower limb muscle pump antagonizing the postural stress.
Another aspect of the authors' findings is the possible interaction of the blood pressure reserve with the now well-known finding that older patients on tilt testing are, at times, not only unaware of impending syncope but also unaware after syncope that it has occurred. It is hoped that this team will continue this study so as to include such patients.
References
[1] Giese A.E., Li V., McKnite S., Sakaguchi S., Ermis C., Samniah N., et al. Impact of age and blood pressure on the lower arterial pressure limit for maintenance of consciousness during passive upright posture in healthy vasovagal fainters: preliminary observations. Europace 2004; 6: 457–462.
[2] Kurbaan A.S., Bowker T.J., Wijesekera N., Franzén A.C., Heaven D., Itty S., et al. Age and haemodynamic responses to tilt testing in those with syncope of unknown origin. J Am Coll Cardiol 2003; 41: 1004–1007.
[3] Bartoletti A., Alboni P., Ammirati F., Brignole M., Del Rosso A., Foglia-Manzillo G., et al. The "Italian Protocol": a simplified head-up tilt testing potentiated with oral nitroglycerin to assess patients with unexplained syncope. Europace 2000; 2: 339–342.
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