Background: The aim of this study was to determine whether endothelial function and inappropriate peripheral vasomotion have a significant role in the pathogenesis of neurally mediated syncope. Methods: In 16 patients (mean age 28.2 +/- 5.8 years) with previous vaso-vagal syncope and in matched healthy subjects, endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent response to glyceryl trinitrate (GTN), 25 mu g, were measured in the brachial artery from high-resolution ultrasonography. Heart rate variability (HRV) analysis at rest and during tilt test was compared between two groups. Results: In the subjects with positive tilt test, all HRV parameters were significant higher respect to subjects with negative tilt test (P < 0.001). The patients with positive tilt test, showed persistent, marked variability of heart rate (HR), due to increased vagal activity with withdrawal sympathetic tone and consequently reduction of blood pressure (BP) (-30.4 +/- 4.2 mmHg, P < 0.001) accompanied by a decrease in HR (-24.3 +/- 4.5 beats/min, P < 0.001) compared to negative tilt test subjects. These findings. prove the real presence of vagal hypertone in patients with syncope. In our study, HR reached values lower than 40 beats/min. FMD in patients with neurally mediated syncope were significantly greater than those in controls (respectively, 9.2 +/- 2.8% vs. 4.6 +/- 1.4%, P < 0.01) whereas no differences were shown in the response to GTN (18.4 +/- 4.4% vs. 16.1 +/- 4.2%, n.s.). Conclusions: The augmented endothelial function and the abnormal vasodilation of peripheral arteries in association with bradycardia play an important role in the development of vaso-vagal syncope in young subjects. (c) 2006 Elsevier SAS. All rights reserved.
Endothelial function in young subjects with vaso-vagal syncope
GALETTA, FABIO;FRANZONI, FERDINANDO;GHIADONI, LORENZO;CARPI, ANGELO;TADDEI, STEFANO;SANTORO, GINO
2006-01-01
Abstract
Background: The aim of this study was to determine whether endothelial function and inappropriate peripheral vasomotion have a significant role in the pathogenesis of neurally mediated syncope. Methods: In 16 patients (mean age 28.2 +/- 5.8 years) with previous vaso-vagal syncope and in matched healthy subjects, endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent response to glyceryl trinitrate (GTN), 25 mu g, were measured in the brachial artery from high-resolution ultrasonography. Heart rate variability (HRV) analysis at rest and during tilt test was compared between two groups. Results: In the subjects with positive tilt test, all HRV parameters were significant higher respect to subjects with negative tilt test (P < 0.001). The patients with positive tilt test, showed persistent, marked variability of heart rate (HR), due to increased vagal activity with withdrawal sympathetic tone and consequently reduction of blood pressure (BP) (-30.4 +/- 4.2 mmHg, P < 0.001) accompanied by a decrease in HR (-24.3 +/- 4.5 beats/min, P < 0.001) compared to negative tilt test subjects. These findings. prove the real presence of vagal hypertone in patients with syncope. In our study, HR reached values lower than 40 beats/min. FMD in patients with neurally mediated syncope were significantly greater than those in controls (respectively, 9.2 +/- 2.8% vs. 4.6 +/- 1.4%, P < 0.01) whereas no differences were shown in the response to GTN (18.4 +/- 4.4% vs. 16.1 +/- 4.2%, n.s.). Conclusions: The augmented endothelial function and the abnormal vasodilation of peripheral arteries in association with bradycardia play an important role in the development of vaso-vagal syncope in young subjects. (c) 2006 Elsevier SAS. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.