1,721,305 research outputs found
Cardiovascular rhythms in vasovagal syncope
No full textVasovagal syncope is a disorder of regulation in which different quantities of neural sympathetic and vagal activities interact, resulting in an unstable autonomic profile before the loss of consciousness. The functional state of the cardiovascular autonomic control is mirrored by the amplitude (power) of the spontaneous fluctuations in RR interval and blood pressure variability and in the pattern of the discharge activity of the post-ganglionic sympathetic fibers (muscle sympathetic nerve activity, MSNA). Power-spectrum and cross-spectrum analysis methodologies enable the identification of the frequency and the quantification of the amplitude of these fluctuations, giving a valuable insight into the autonomic changes preceding vasovagal events which may remain hidden when simple heart rate or blood pressure values are considered
Tilt test and orthostatic intolerance: abnormalities in the neural sympathetic response to gravitational stimulus
No full textIn the present manuscript the different methodologies aimed at assessing the autonomic profile in humans during a gravitational stimulus have been described. In addition, strengths and drawbacks of the tilt test in relation to occasional orthostatic intolerance were addressed. Finally, different autonomic abnormalities underlying occasional and chronic orthostatic intolerance syndromes have been schematically highlighted. The direct recording of the neural sympathetic discharge from the peroneal nerve (MSNA), in spite of its invasive nature, still represents the recognized reference to quantify the changes in the sympathetic activity to the vessels attending postural modifications. The increase of plasma norepinephrine during a tilt test is achieved by both an increase in plasma spillover and a concomitant decrease in systemic clearance. Changes in the indices of cardiac sympathetic and vagal modulation may also be quantified during a tilt test by power spectrum analysis of RR interval variability. The spectral markers of cardiac autonomic control, if evaluated concomitantly with MSNA, may contribute to assess abnormalities in the regional distribution of the sympathetic activity to the heart and the vessels. The capability of the tilt test of reproducing a vasovagal event or of inducing "false positive responses" seems to be markedly affected by the age, thus suggesting that additional or different etiopathogenetic mechanisms might be involved in the loss of consciousness in older as compared to younger subjects. In subjects suffering from occasional or habitual neurally mediated syncope an increase or, respectively, a decrease in cardiac and vascular sympathetic modulation has been documented before the loss of consciousness. In patients with pure autonomic failure, a global dysautonomia affecting both the sympathetic and the vagal modulation to the heart, seems to be present. In chronic orthostatic intolerance, the most common form of dysautonomia of young women, an abnormal regional distribution of sympathetic activity has been hypothesized during up-right posture. Indeed, during standing a blunted increase of sympathetic activity to the vessels is attended by a cardiac sympathetic overactivity leading to an exaggerated tachycardi
Gli impianti di amplificazione sonora per gli spettacoli all'aperto. Tipologie e soluzioni per limitare l'impatto acustico indesiderato
No full text
Friction compensation in the interstand looper of hot strip mills: a sliding mode control approach
No full textIncrease of myeloid microvesicles in the cerebrospinal fluid as biomarkers of microglia/microphage activation in neurological disorders
No full textThe present invention relates to a method for the diagnosis and/or prognosis of a
neurological disease characterized by an inflammatory process as well as a method for
predicting and /or monitoring the efficacy of a treatment for a neurological pathology. The
methods are based on the measurement of the amount of myeloid derived microvesicles in
a cerebrospinal fluid sample
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