Print Email Facebook Twitter Sublingual nitroglycerin used in routine tilt testing provokes a cardiac output-mediated vasovagal response Title Sublingual nitroglycerin used in routine tilt testing provokes a cardiac output-mediated vasovagal response Author Gisolf, J. Westerhof, B.E. van Dijk, N. Wesseling, K.H. Wieling, W. Karemaker, J.M. TNO Industrie Publication year 2004 Abstract Objectives We set out to determine the effect of sublingual nitroglycerin (NTG), as used during routine tilt testing in patients with unexplained syncope, on hemodynamic characteristics and baroreflex control of heart rate (HR) and systemic vascular resistance (SVR). Background Nitroglycerin is used in tilt testing to elicit a vasovagal response. It is known to induce venous dilation and enhance pooling. Also, NTG is lipophilic and readily passes cell membranes, and animal studies suggest a sympatho-inhibitory effect of NTG on circulatory control. Methods Routine tilt testing was conducted in 39 patients with suspected vasovagal syncope (age 36 ± 16 years, 18 females). Patients were otherwise healthy and free of medication. Before a loss of consciousness set in, oncoming syncope was cut short by tilt-back or counter-maneuvers. Finger arterial pressure was monitored continuously (Finapres). Left ventricular stroke volume (SV) was computed from the pressure pulsations (Modelflow). Spontaneous baroreflex control of HR was estimated in the time and frequency domains. Results During tilt testing, 22 patients developed presyncope. After NTG administration but before presyncope, SV and cardiac output (CO) decreased (p < 0.001), whereas SVR and HR increased (p < 0.001) in all patients. Arterial pressure was initially maintained. Baroreflex sensitivity decreased after NTG. On Cox regression analysis, the occurrence of a vasovagal response was related to a drop in SV after NTG (hazard ratio 0.86, p = 0.005). Conclusions The cardiovascular response to NTG is similar in vasovagal and non-vasovagal patients, but more pronounced in those with tilt-positive results. The NTG-facilitated presyncope appears to be CO-mediated, and there is no evidence of NTG-induced sympathetic inhibition. Subject Baroreflex sensitivityCardiac outputDiastolic arterial pressureHeart rateInterbeat intervalNitric oxideSodium nitroprussideStroke volumeSystolic arterial pressureGlyceryl trinitrateCardiovascular responseCardiovascular systemDiagnostic procedureHemodynamicsPressoreceptor reflexVagus reflexVein dilatationCardiac OutputNitroglycerinProportional Hazards ModelsTilt-Table TestVascular Resistance To reference this document use: http://resolver.tudelft.nl/uuid:eb4a3143-6f4a-4cf1-baef-f73d35b7d183 TNO identifier 280219 Publisher Elsevier, Amsterdam ISSN 0735-1097 Source Journal of the American College of Cardiology, 44 (3), 588-593 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.