Search results for "Heart"
showing 10 items of 3201 documents
Strength and Latency of the HP-SAP Closed Loop Variability Interactions in Subjects Prone to Develop Postural Syncope
2019
The coupling and latency between heart period (HP) and systolic arterial pressure (SAP) variability can be investigated along the two arms of the HP-SAP closed loop, namely along the baroreflex feedback from SAP to HP, and along the feedforward pathway from HP to SAP. This study investigates the HP-SAP closed loop variability interactions through cross-correlation function (CCF). Coupling strength and delay between HP and SAP variability series were monitored in 13 subjects prone to develop orthostatic syncope (SYNC, 28±9 yrs, 5 males) and in 13 subjects with no history of postural syncope (noSYNC, age: 27±8 yrs, 5 males). Analysis was carried out at rest in supine position (REST) and durin…
Effects of electromyostimulation and strength training on muscle soreness, muscle damage and sympathetic activation.
1995
Electromyostimulation (EMS) is known to develop muscular strength and hypertrophy. The aim of this study was to compare EMS exercise-induced damage with concentric (CONC) exercise-induced damage. Twelve male athletes were randomly assigned to concentric exercise (five sets of 6 voluntary contractions) or to EMS (30 contractions of 6 s duration, 20 s rest between contractions) on day 0 (D0). The load was 80% of the maximal isometric force. Criterion measures of plasma creatine kinase (CK) activity and lactate dehydrogenase (LDH) activity, and subjective ratings of muscle soreness and urinary catecholamines, were assessed 1 day before and for 3 days after exercise. Among the members of the EM…
Exploring directionality in spontaneous heart period and systolic pressure variability interactions in humans: implications in the evaluation of baro…
2004
Although in physiological conditions RR interval and systolic arterial pressure (SAP) are likely to interact in a closed loop, the traditional cross-spectral analysis cannot distinguish feedback (FB) from feedforward (FF) influences. In this study, a causal approach was applied for calculating the coherence from SAP to RR ( Ks-r) and from RR to SAP ( Kr-s) and the gain and phase of the baroreflex transfer function. The method was applied, compared with the noncausal one, to RR and SAP series taken from 15 healthy young subjects in the supine position and after passive head-up tilt. For the low frequency (0.04–0.15 Hz) spectral component, the enhanced FF coupling ( Kr-s = 0.59 ± 0.21, signi…
Impact of chronic psychosocial stress on autonomic cardiovascular regulation in otherwise healthy subjects.
2005
Elevated psychosocial stress might favor the occurrence of cardiovascular disease; however, mechanisms are incompletely understood. We hypothesized that patients (n=126; 44±1 years of age) referred to an internal medicine clinic because of symptoms related to chronic psychosocial stress would demonstrate signs of autonomic dysregulation compared with controls (n=132; 42±1 years of age). We used autoregressive spectral analysis of RR interval variability to obtain indirect markers of sympathetic and of vagal (respectively, low-frequency and high-frequency components, both expressed in normalized units) oscillatory modulation of sinoatrial node, as well as of sympathetic vasomotor regulation…
The Effects of Sympathetic Inhibition on Metabolic and Cardiopulmonary Responses to Exercise in Hypoxic Conditions.
2015
Objective Pre-exertion skeletal muscle glycogen content is an important physiological determinant of endurance exercise performance: low glycogen stores contribute to premature fatigue. In low-oxygen environments (hypoxia), the important contribution of carbohydrates to endurance performance is further enhanced as glucose and glycogen dependence is increased; however, the insulin sensitivity of healthy adult humans is decreased. In light of this insulin resistance, maintaining skeletal muscle glycogen in hypoxia becomes difficult, and subsequent endurance performance is impaired. Sympathetic inhibition promotes insulin sensitivity in hypoxia but may impair hypoxic exercise performance, in p…
Depressive symptoms and attenuated physiological reactivity to laboratory stressors.
2010
There is evidence that depressive symptoms are associated with attenuated physiological reactivity to active stressors. However, it is not known whether blunted reactivity in depressed individuals is stressor-specific. We examined cardiovascular and electrodermal reactivity in non-clinical participants with varying levels of depressive symptoms to different active and passive stressors. Depressive symptoms were inversely related to both blood pressure and skin conductance reactivity during a public speaking task and the viewing of the speech video. However, no effects were found during a cold pressor task. Together these findings suggest that depressive symptoms are related to attenuated sy…
Stress and thermoregulation: different sympathetic responses and different effects on experimental pain.
2009
Stress and thermoregulation both activate the sympathetic nervous system (SNS) but might differently affect pain. Studies investigating possible interactions in patients are problematic because of the high prevalence of SNS disturbances in patients. We therefore analyzed the influence of these different sympathetic challenges on experimentally-induced pain in healthy subjects. SNS was activated in two different ways: by mental stress (Stroop task, mental arithmetic task), and by thermoregulatory stimulation using a water-perfused thermal suit (7 degrees C, 32 degrees C, or 50 degrees C). Attentional effects of the mental stress tasks were controlled by using easy control tasks. Both, stress…
Effects of Nebivolol versus Carvedilol on Left Ventricular Function in Patients with Chronic Heart Failure and Reduced Left Ventricular Systolic Func…
2006
Beta-adrenoceptor antagonist (beta-blocker) therapy results in a significant improvement in left ventricular (LV) systolic function and prognosis in patients with chronic heart failure. Both carvedilol and nebivolol produce hemodynamic and clinical benefits in chronic heart failure, but it is unknown whether their peculiar pharmacologic properties produce different effects on LV function.To assess the effects on LV function of nebivolol compared with carvedilol in patients with chronic heart failure and reduced LV systolic function.Seventy patients with a LV ejection fractionor=40% and in New York Heart Association (NYHA) functional class II or III were randomly assigned to receive carvedil…
Clopidogrel and aspirin in the prevention of thromboembolic complications after mechanical aortic valve replacement (CAPTA)
2003
Axel Schlitt*, Ralf S. von Bardeleben, Anne Ehrlich, Antje Eimermacher, Dirk Peetz, Manfred Dahm, Hans J. Rupprecht Department of Medicine II, Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131 Mainz, Germany Coordination Center for Clinical Studies, Johannes Gutenberg-University Mainz, Mainz, Germany Clinic for Clinical Chemistry and Laboratory Medicine, Johannes Gutenberg-University Mainz, Mainz, Germany Department of Cardiothoracic and Vascular Surgery, Johannes Gutenberg-University Mainz, Mainz, Germany
Prevalence and characterization of cardiac involvement in Hunter syndrome.
2011
To assess the prevalence of cardiovascular signs and symptoms in a large group of patients with Hunter syndrome, an X-linked metabolic disorder caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase.The Hunter Outcome Survey was established to characterize the natural history of Hunter syndrome and to assess the response to enzyme replacement therapy. Echocardiographic and electrocardiographic examination results were available for 102 patients who were enzyme replacement therapy-naïve in the Hunter Outcome Survey (median age at examination, approximately 8 years) as of Jan 23, 2009.The most common cardiovascular finding was valve disease, which was present in 63% of patients.…