224 Sympathetic nervous system and PRA are involved in the lack of aldosterone increase during HUT-induced vasovagal syncope

EP Europace, Jun 2005

Gajek, J., Zysko, D., Mazurek, W.

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224 Sympathetic nervous system and PRA are involved in the lack of aldosterone increase during HUT-induced vasovagal syncope

G. Russo 0 A. Porta 0 G. Buja 0 S. Cerutti 0 S. Iliceto 0 0 1Bassano del Grappa, Italy; 2University of Padua, Department of CaMiology , Padova , Italy; 3University of Milan, Department of Preclinic Sciences , Milan , Italy; 4polytechnic of Milan, Department 0 Bioengineering , Milan , Italy 46.84-21.9 years, 43% male). The early pre-established patterns of BP and HR were: O/71:drop in systolic BP > 20 mmHg (SO/H) or >10 mmHg drop in diastolic BP (DOH) within the first 5 minutes of orthostatism; PT: HR increase > 30 bpm within the first 5 minutes orthostatism with a HR > 120 bpm in the absence of hypotension; progressive decrease (PD): slow and continous fall in BP until the end of the test; Normal(NP): none of above abnormalities is present. Results: a normal initial response of BP and HR to orthostatism was the most prevalent in both negative HUT and B-H pts (76.9% and 64,4%, p<.05). Individual patterns showed the following values: NP HOS HOD PD PT - Purpose Neurally-mediated syncope (NMS) resuks from a complex interaction among autonomic afferent signals, cortical modulation, and bulbar integration. Upright tik test (UTT) offers the opportunity to study pathophysiological mechanisms leading to reflex syncope. The aim of our study was to evaluate the modifications of autonomic activity leading to tik-induced syncope by heart rate variability (HRV) analysis. Method We studied 40 patients with a mean age of 47.94-17yrs. Frequency domain analysis of heart rate variability (HRV) was performed on 2 periods of 300 beats recordings: at baseline, in supine position, and after 5 minutes of 60 ? tilt. Results UTT was positive in 26 patients (65%), the responses were vasodepressive in 10, mixed in 16. Baseline LF and I:IF components did not show significant difference between subjects with positive or negative test (normalized units, /:IF: 38.814-19 versus 36.944-19, p= NS; LF: 48.944-26 versus 50.844-22, p= NS). The patients with mixed reactions were characterized by higher values of HF at baseline (normalized units, 43.884-20 versus 25.844-14, p<0.02), and higher values of LF during tilt (624-16 versus 45.614-26, p<0.05), in comparison with patients with vasodepressive responses. During UTT, HRV parameters showed similar changes in patients with positive or negative test. However, subjects with mixed reactions were characterized by a reduction of I:IF during UTT (normalized units, from 43.884-20 to 28.284-12, p<0.005), whereas the others by an increase of the same component (normalized units, from 25.844-14 to 41.084-30, p<0.005). Conclusions In conclusion, baseline evaluation of HRV was not useful to identify patients with positive response to UTT. On the contrary, the modifications of HRV during UTT seem to indicate that patients with a cardioinhibitory response were characterized by an increase of sympathetic activity during the test, that could represent an essential factor to induce a stronger vagal reaction on the sinus node, whereas in subjects with vasodepressive responses there is a inadequate increase of the sympathetic drive, probably causing a failure of peripheral vasoconstriction. 223 The bradycardia-hypotension reaction during head-up tilt test in patients with syncope: prevalence and value of blood pressure and heart rate behavior during the early stage of the test G.A. Ruiz 1, R. Chirife 2, M.C. Tentori 2, D. Dasso 2, R. Gelpi 3, J.C. Peffetto 4 1Hospital Juan A. Fernandez, Florida, Argentina; 2Hospital Juan A Fernandez, Cardiology, Buenos Aires, Argentina; 3Facultad de Medicina. UBA, Instituto Fisiopatologia Cardiovascula, Buenos Aires, Argentina; 4Facultad de Ingenieria, UBA, Biomedicina, Buenos Aires, Argentina The blood pressure (BP) and heart rate (HR) behavior during the early stage of the tik test (TI?) define different orthostatic disorders: postural tachycardia (PT), orthostatic hypotension (systolic SO/H, diastolic DOH) and vasovagal reaction (Normal initial behavior followed by an abrupt and relatively late fall in ]3P with or without HR decrease). The mixed and cardioinhibitory responses are characterized by a bradycardiahypotension reaction (]3-H) and syncope. Objective: to assess the prevalence, sensitivity, specificity and predictive value of different pre-established patterns of ]3P and HR behavior during the early stages of HUT for a ]3-/7Ireaction. Methods: 442 pts with >1 syncope or mukiple presyncope episodes of unknown origin were included: 138 developed ]3-/7Ireaction during HUT (age 38.14-21.9 years, 50% male) while 304 pts had HUT (-) (age 64 12 9 10 9 SP (+) PV (-) PV SS: sensitivity,SP: specificity; PV: predictive value Conclusion: different early patterns of ]3P and HR defining different orthostatic intolerance disorders may precede an abrupt bradicardiahypotension reaction. The most prevalent one is the normal behavior of ]3P and HR in early TF. None of them has an elevated sensitivity or (+) predictive value. The mechanism leading to ]3-/7Ireaction is not uniqu (...truncated)


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Gajek, J., Zysko, D., Mazurek, W.. 224 Sympathetic nervous system and PRA are involved in the lack of aldosterone increase during HUT-induced vasovagal syncope, EP Europace, 2005, pp. 45-46, Volume 7, Issue Supplement_1, DOI: 10.1016/eupace/7.Supplement_1.45-b