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Biomedical subjects

A Malliani

Publications and source records attributed to A Malliani.

222 records · Page 13Linked to original sources
PubMedDate not supplied

A controlled study of the effects of mental relaxation on autonomic excitatory responses in healthy subjects.

OBJECTIVE: Circumstantial evidence indicates that, in the presence of a suitable substratum, sudden, behaviorally induced increases in sympathetic drive to the cardiovascular system might play an important physiopathological role in various conditions, ranging from arterial hypertension to sudden coronary death. Accordingly, it might be useful to study the effects of behavioral interventions, such as mental relaxation, that might be capable of blunting excitatory autonomic responses. It would also be preferable to study healthy subjects in whom autonomic control is not modified by the presence of disease, and to use noninvasive approaches to minimize the possible emotional impact produced by invasive recordings. METHODS: We examined healthy subjects who were either subjected to relaxation training (N = 13) or sham relaxation (N = 12). An additional group, treated with beta-adrenergic blockade (N = 12), was also examined. Spectral and cross-spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided quantitative markers of sympathovagal balance modulating the sinoatrial (SA) node, of sympathetic vasomotor modulation, and of the gain of the arterial pressure/heart period baroreflex (index alpha). Subjects were studied at rest, during standing, and during mental arithmetic. RESULTS: Data indicate that both beta-adrenergic blockade and relaxation training significantly blunted the excitatory autonomic responses to standing and to mental arithmetic. Indices of sympathetic modulation also seemed reduced by beta blockade at rest. No changes were observed with sham training. CONCLUSIONS: Frequency domain analysis of cardiovascular variabilities, using a totally noninvasive approach, indicates that relaxation training significantly blunts the excitatory autonomic changes produced by standardized behavioral laboratory stimuli.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

[Syncope and work. STePS study (Short Term Prognosis of Syncope)].

BACKGROUND: Recurrent syncope is a common medical problem responsible for 3-5% of emergency department (ED) accesses and 1-6% of hospital admissions. If syncope occurs in a subject working in a critical safety task, the consequences of this event might be very dangerous for the worker, colleagues, others or for the environment. Therefore, syncope management is a major problem for occupational medicine, converning the general safety at work. AIMS: To evaluate the syncope events in a group of potential workers aged 18 to 65 years; to evaluate the symptoms preceding syncope and the presence of associated illnesses and recurrent events. POPULATION AND RESULTS: This study is part of the prospective study STePS (Short Term Prognosis of Syncope), and included 305 consecutive patients (aged 18-65 years, female 56%) who had syncope as a main symptom and presented at ED of four general hospitals in the Milan area, Italy, between the 23rd of January and 30th of June 2004. The 24% of subjects were hospitalized. In 21% the syncope occurs suddenly without any preceding symptom. The 67% of subjects didn't have any important illness at the time. 50% of subjects had recurrent syncope. In four subjects another syncope occurred in a 10 day follow-up. CONCLUSIONS: occupational medicine should consider syncope scrupulously. Proper diagnostic management is important to permit a correct evaluation of work safety issues.

Adolescent↗
PubMedDate not supplied

Neurovegetative regulation and cardiovascular diseases.

Heart period and arterial pressure short term variabilities contain rhythmic oscillations which might provide information on neural mechanisms regulating cardiovascular function. Continuous electrocardiographic and/or arterial pressure signals, after appropriate analogue to digital conversion, furnish the time series which constitute the basis for spectral analysis of their variabilities. Under stationary conditions, this methodology can be utilized to assess both total variability and the power and center frequency of each rhythmic component. Human physiological and animal studies support the hypothesis that the low frequency (LF) component, around 0.1 Hz, is a marker of sympathetic modulation of both R-R and arterial pressure variabilities, while the high frequency (HF) component, around 0.25 Hz, is a marker of vagal modulation of R-R variability. LF/HF ratio of R-R variability is a marker of sympatho-vagal balance. Spectral components when assessed for a 24-hour period evidence marked circadian rhythmicity with sympathetic predominance during the day and vagal predominance at night. Various pathophysiological conditions including arterial hypertension, ischemic heart disease, cardiac transplantation, congestive heart failure, Chagas' disease and diabetic neuropathy have been explored with this methodology, and a new quantitative evaluation of the alterations in sympatho-vagal balance which seem to characterize these abnormal states has been obtained. The study of cardiovascular rhythmicity, i.e. an analysis performed in the frequency domain, although based on indirect spectral markers, seems to offer a new clinical tool for the exploration of cardiovascular neural control in health and disease.

Cardiovascular Diseases↗
PubMedDate not supplied

"Central command" and sympathetic activation.

The concepts of "central command" and of peripheral feedback mechanisms are analysed in order to individuate the main regulatory components of sympathetic efferent activity. In recent years a new afferent channel has been described: it consists of cardiovascular sympathetic afferent fibres which play a tonic function in the regulation of the sympathetic outflow. This afferent channel mediates reflexes which are mainly excitatory in nature with positive feedback characteristics. In this way, each particular haemodynamic neurally-regulated state can be hypothesized as under the control of "central command" and of opposite peripheral influences represented by the continuous interaction of negative and positive feedback mechanisms.

Afferent Pathways↗