Search Results
Results 551 - 600 of 1844
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Campbell Hamish A - - 2006
Autonomic control of heart rate variability and the central location of vagal preganglionic neurones (VPN) were examined in the rattlesnake (Crotalus durissus terrificus), in order to determine whether respiratory sinus arrhythmia (RSA) occurred in a similar manner to that described for mammals. Resting ECG signals were recorded in undisturbed snakes ...
Gadegbeku Crystal A - - 2006
OBJECTIVE AND DESIGN: Plasma lipids enhance alpha1-adrenoceptor pressor sensitivity, impair baroreflex function, and correlate with increased blood pressure. This clinical study was designed to determine whether the enhanced alpha1-pressor sensitivity induced by acute hyperlipidemia is primarily mediated by increased vascular alpha1 responsiveness, reduced baroreflex sensitivity (BRS) or both. METHOD: Regional ...
Schumacher Autumn M - - 2006
Cardiac variability can be assessed from two perspectives: beat-to-beat performance and continuous performance during the cardiac cycle. Linear analysis techniques assess cardiac variability by measuring the physical attributes of a signal, whereas nonlinear techniques evaluate signal dynamics. This study sought to determine if recurrence quantification analysis (RQA), a nonlinear technique, ...
Dias Fernando A L - - 2006
Although it has been suggested that in cardiac muscle the phosphorylation level of myosin regulatory light chain (RLC) correlates with frequency of stimulation, its significance in the modulation of the force-frequency and pressure-frequency relationships remains unclear. We examined the role of RLC phosphorylation on the force-frequency relation (papillary muscles), the ...
Paul-Labrador Maura - - 2006
BACKGROUND: The metabolic syndrome is thought to be a contributor to coronary heart disease (CHD), and components of the syndrome have been identified as possible therapeutic targets. Previous data implicate neurohumoral activation related to psychosocial stress as a contributor to the metabolic syndrome. The aim of this study was to ...
Polson Jaimie W - - 2006
BACKGROUND: Coarctation of the aorta (CoA) is associated with hypertension and abnormalities of blood pressure control, which persist after late repair. Assumptions that neonatal repair would prevent development of blood pressure abnormalities have not been supported by recent data. We hypothesized that early pathological adjustment of autonomic cardiovascular function may ...
Shibata Shigeki - - 2006
Cardiovascular variability reflects autonomic regulation of blood pressure (BP) and heart rate (HR). However, systolic BP (SBP) variability also may be induced by fluctuations in stroke volume through left ventricular end-diastolic pressure (LVEDP) variability via dynamic ventricular-arterial coupling during respiration. We hypothesized that dynamic ventricular-arterial coupling is modulated by changes ...
Wirch Jennifer L - - 2006
The primary objective of this study was to develop a cold pressor test (CPT) protocol to evaluate cardiac autonomic function. Secondary objectives were to assess CPT protocol reliability and to examine gender differences in response to orthostatic stress and the CPT. Healthy, normotensive men and women (n = 12 per ...
Gipson C L - - 2006
Changes in cardiac output may occur during insufflation for laparoscopic procedures. However, there are limited data regarding its potential effects on cerebral oxygenation. Cerebral oxygenation (ScO(2)), end tidal CO(2), heart rate, blood pressure and oxygen saturation by pulse oximetry were recorded every 5 minutes prior to insufflation, during insufflation and ...
Diaz Tulio - - 2006
The arterial baroreflex is important for beat-to-beat arterial pressure control and its sensitivity has predictive value for clinical outcomes in a myriad of cardiovascular conditions. Given this, researchers have sought approaches for baroreflex assessment that are not invasive and easily obtained. These techniques have exploited the beat-by-beat parallel changes in ...
Monahan Kevin D - - 2006
Baroreflex function is impaired in patients with obstructive sleep apnoea. We tested the hypothesis that short-term exposure to repetitive hypoxic apnoeas (RHA) produces prolonged impairment in baroreflex function. Baroreflex function was determined using the modified Oxford technique in 14 subjects (26 +/- 1 years). Baroreflex sensitivity (BRS) was quantified from ...
Beckers Frank - - 2006
1. The present study assesses the effects of autonomic blockade (alpha- and beta-adrenoceptor and cholinergic) on cardiovascular function studied by heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity in rats using non-linear dynamics. Little is known about the influence of pharmacological autonomic nervous system interventions on non-linear ...
Singh D - - 2006
The background to heart rate variability (HRV) and blood pressure variability (BPV), and their determinants and physiological correlates, remain obscure. The impact of age must be taken into account if HRV and BPV are used for predictive purposes in clinical settings. Healthy subjects show wide inter-individual variation in their heart ...
Huang C-J - - 2006
BACKGROUND: Peri-operative hymodynamic instability is one of the major concerns for anesthesiologists when performing general anesthesia for individuals with autonomic dysfunction. The purpose of this study was to examine the potential usage of pre-operative measurement of heart rate variability (HRV) in identifying which individuals, with or without diabetes, may be ...
Solem Kristian - - 2006
Clinical techniques for early detection of acute hypotension during conventional hemodialysis treatment are lacking, even though intradialytic hypotension is the most common acute complication. In this article, intradialytic hypotension is identified by means of signal analysis of data recorded at two clinics. The database consists of 30 treatments with concurrently ...
Oginosawa Yasushi - - 2006
INTRODUCTION: Conventional baroreceptor-heart rate (HR) reflex sensitivity cannot be examined in chronotropically incompetent patients or in pacemaker recipients. However, cardiac baroreceptor reflex sensitivity (BRS)-stroke volume (SV), which is closely and linearly correlated with BRS-HR, may be an alternative in that population. The aim of this study was to compare the ...
Fox Justin M - - 2006
Pressure-volume analysis has provided critical insight into ventricular mechanics, and it has elucidated the underlying mechanisms of heart failure (HF). Renewed interest in ventriculovascular coupling, the interaction of the left ventricle and the arterial system, has developed from recent investigations focusing on the importance of heart rate control in systolic ...
Atlasz Tamás - - 2006
The aim of the present study was to test whether the electromagnetic field emitted by standard GSM mobile phones results in changes in heart rate (HR) and heart rate variability (HRV) of 35 healthy young male and female subjects. Two parallel signals, electrocardiogram and infrared surface plethysmogram were recorded and ...
Fujiwara Y - - 2006
Heart rate variability (HRV) was investigated using a new technique for time series analysis combining the maximum entropy method and non-linear least squares method -- the 'MemCalc method' -- in patients undergoing general anesthesia with sevoflurane and fentanyl for elective surgery. As the occurrence of junctional rhythm coincided with the ...
Chen Jay - - 2006
The purpose of this manuscript is to review the current literature regarding the role of the autonomic nervous system (ANS) in atrial fibrillation (AF). We will be reviewing its effect on initiation, maintenance, and termination of AF, with emphasis on the role of baroreflex gain (BRG) and autonomic reflexes in ...
Mager Donald E - - 2006
Dietary restriction (DR) has been shown to increase life span, delay or prevent age-associated diseases, and improve functional and metabolic cardiovascular risk factors in rodents and other species. To investigate the effects of DR on beat-to-beat heart rate and diastolic blood pressure variability (HRV and DPV) in male Sprague-Dawley rats, ...
Haensch Carl-Albrecht - - 2006
Extrasystoles occur in normal subjects but are significant more frequently (16.25% vs. 55%; chi(2) = 19.3; P < 0.001) seen in Parkinson's disease (PD) patients. The extrasystolic decreases in stroke volume and systolic pressure activate sympathetic vasomotor innervation and lead to a blood pressure increase for a few heartbeats. The ...
Deguchi K - - 2006
Although heart rate (HR) responses to hyperventilation (HV) have been used as a cardiovascular autonomic function test, autonomic involvement during HV remains uncertain. To clarify the relationship between autonomic activity and cardiovascular changes during HV, we compared cardiovascular responses during HV among subjects with different autonomic function, namely 16 patients ...
Norozi Kambiz - - 2006
Heart failure (HF) is a major problem in the long-term follow-up of adults with congenital heart disease (CHD) after cardiac surgery. The purpose of this study was to evaluate risk factors for HF in patients with CHD. N-terminal-pro-brain natriuretic peptide and maximal oxygen uptake (VO2max) were measured in 345 consecutive ...
Siu Chung-Wah - - 2006
Ventricular tachyarrhythmias may occur during intravenous arsenic trioxide (As2O3). This has not happened during oral As2O3. Sixteen patients were studied by electrocardiography and 24-hour Holter monitoring at baseline, during and after oral As2O3 (As2O3-ON, As2O3-OFF). QT and corrected QT (QTc) were significantly longer during As2O3-ON than in As2O3-OFF, but QT ...
van Vliet J A - - 2006
While facial autonomic signs are prominent during cluster headache (CH) attacks, cardiovascular autonomic changes have been described in few CH patients. Cardiovascular autonomic function tests (AFT) can be used to assess general autonomic function in CH patients in different stages of the disease. We aimed to assess whether general autonomic ...
Vallejo Maite - - 2006
Particulate air pollution has been related with cardiopulmonary morbidity and mortality. Recent studies have shown that an increase in particulate matter (PM)(2.5) ambient concentrations was associated with a decrease in heart rate variability (HRV) in the elderly with cardiovascular conditions, which could increase the risk of death. In order to ...
Tsuchiya S - - 2006
BACKGROUND AND OBJECTIVE: Thiopental has been reported to reduce sympathetic tone, however, it is not clear whether change in heart rate variability is associated with depth of anaesthesia. The purpose of the present study was to evaluate changes in heart rate variability at different depths of hypnosis during induction of ...
Ogawa Yojiro - - 2006
STUDY OBJECTIVE: To evaluate the different effects on autonomic circulatory control during volatile induction/maintenance of anesthesia (VIMA) vs total intravenous anesthesia (TIVA). DESIGN: Prospective study. SETTING: Operating theater of a university hospital. PATIENTS: Twenty patients, with American Society of Anesthesiologists physical status of I or II, were randomly allocated into ...
Connes Philippe - - 2006
Sickle cell trait (SCT) is a genetic disease affecting the synthesis of normal haemoglobin (Hb) and marked by the heterozygous presence of HbA and HbS. Some studies have suggested that SCT carriers might be prone to vascular alterations, cardiac ischaemia and arrhythmias leading, in some subjects, to sudden death. It ...
Hanss Robert - - 2006
BACKGROUND: Hypotension due to vasodilatation after spinal anesthesia (SA) may be harmful. Heart rate variability, an indirect measure of autonomic control, may predict hypotension. METHODS: One hundred patients were studied. Retrospectively, heart rate variability was analyzed in 30 patients, classified depending on the lowest systolic blood pressure (SBP) after SA. ...
Khurana Ramesh K - - 2006
Application of cold to the face evokes potent bradycardia and a pressor response, similar to the diving reflex. However, the role of the baroreceptors in this response is unclear. Ten healthy controls and two patients with baroreflex impairment were recruited. A cold face test (CFT) was induced by the application ...
Milutinović Sanja - - 2006
The role of neurally born acetylcholine in the central modulation of cardiovascular short-term variability was assessed using a pharmacological probe physostigmine, a cholinesterase inhibitor that can act centrally also. Experiments were performed in instrumented conscious rats. Equidistant sampling at 20 Hz of systolic arterial pressure (SAP), diastolic arterial pressure (DAP) ...
Lai C J - - 2006
Long-term exposure to intermittent hypoxia (IH), such as that occurring in association with sleep apnea, may result in systemic hypertension; however, the time course changes in arterial pressure, autonomic functions, and baroreflex sensitivity are still unclear. We investigated the changes in cardiovascular neural regulations during the development of chronic IH-induced ...
Wiegerinck Rob F - - 2006
BACKGROUND: Patients with heart failure (HF) have an increased QRS duration, usually attributed to decreased conduction velocity (CV) due to ionic remodeling but which may alternatively result from increased heart size or cellular uncoupling. We investigated the relationship between QRS width, heart size, intercellular coupling, and CV in a rabbit ...
Fu Chin-Hua - - 2006
The incidence of cardiovascular disease is higher in postmenopausal women than in premenopausal women. We hypothesized that long-term vegetarian diets might modulate cardiovascular autonomic functions measured by frequency-domain techniques in healthy postmenopausal women. A total of 35 healthy vegetarians (mean age +/- SEM 55.0 +/- 1.3 years) who had been ...
Freeman Roy - - 2006
Cardiovascular autonomic manifestations of seizures occur frequently in the epileptic population. Common manifestations include alterations in heart rate and rhythm, blood pressure, ECG changes and chest pain. The neuroanatomical and neurophysiological underpinnings of these autonomic manifestations are not been fully elucidated. Diagnostic confusion may arise when ictal symptoms are confined ...
Chern Chang-Ming - - 2006
Baroreflex sensitivity (BRS) and heart rate variability (HRV) are potential therapeutic targets. The present study was conducted to assess changes in BRS and HRV after monotherapy with losartan versus that of atenolol in uncomplicated essential hypertension. Thirty subjects with uncomplicated essential hypertension were randomized to receive atenolol 50 mg to ...
van Orshoven Narender P - - 2006
This study comprises assessment of autonomic function in irritable bowel syndrome (IBS) patients, focusing on meal-related changes. In 18 IBS patients (4 males, mean age 45+/-3.0 [SEM] years) and 19 healthy volunteers (6 males, mean age 41+/-3.5 years) blood pressure, heart rate, heart rate variability and muscle sympathetic nerve activity ...
Samuels E R - - 2006
The noradrenergic locus coeruleus is a major wakefulness-promoting nucleus of the brain, which is also involved in the regulation of autonomic and endocrine functions. The activity of the locus coeruleus is believed to be tonically enhanced by a mesocoerulear dopaminergic pathway arising from the ventral tegmental area of the midbrain. ...
Hsiu H - - 2006
The effects of mechanical stimulation on hemodynamics, such as due to mechanotransduction in vascular endothelial cells, have been widely discussed recently. We previously proposed a resonance model in which the arterial system is treated as a pressure-transmitting system, and suggested that the application of external mechanical stimulation with frequencies near ...
Collins Heidi L - - 2006
The autonomic nervous system modulates cardiac electrophysiology and abnormalities of autonomic function are known to increase the risk of ventricular arrhythmias. The abnormal and unstable autonomic control of the cardiovascular system following spinal cord injury also is well known. For example, individuals with mid-thoracic spinal cord injury have elevated resting ...
Faes Luca - - 2006
A causal approach to the calculation of coherence and transfer function between systolic pressure (SP) and RR interval variability was applied in eight patients and eight control subjects during prolonged tilt test for investigating the impairment of cardiovascular control related to neurally mediated syncope. The causal analysis showed a depressed ...
Hopper James W - - 2006
OBJECTIVE: Evidence of elevated basal heart rate (HR) in posttraumatic stress disorder (PTSD) has been interpreted in terms of elevated sympathetic cardiac activity, as have possible increased cardiovascular disease risks and outcomes associated with elevated HR. Yet it is well-established that the parasympathetic branch of the autonomic nervous system not ...
Hsu Chih-Chieh - - 2006
In this research, heart rate variability (HRV), pulse rate variability (PRV) and human skin conductance (SC) of all acupoints on Heart Meridian were used to evaluate the effects of electrical acupuncture (EA) on acupoint BL15 (Bladder Meridian). Ten healthy volunteers (aged 23 +/- 6) were selected as the control group ...
Wang Gang - - 2006
To investigate the effects of impaired glucose metabolism (IGM) on cardiovascular autonomic nervous systems in essential hypertensive (EH) patients by comparing heart rate variability (HRV) and blood pressure variability (BPV) in EH patients with or without type 2 diabetes mellitus (T2DM). Simultaneous 24-h recordings of ambulatory ECG and blood pressure ...
Princi Tanja - - 2006
Congenital central hypoventilation syndrome (CCHS) is characterised by the failure of the autonomic control of breathing and is defined as a multi-system disorder with symptoms of diffuse autonomic nervous system dysfunction. The present study, considering the heart rate variability (HRV) parameters as expression of cardiac autonomic nervous system activity, reports ...
Baselli Giuseppe - - 2006
Arterial pressure (AP) and heart rate (HR) waves have long been recognized as an important sign of cardiovascular regulation, however, the underlying interactions involving vasomotion, arterial mechanisms and neural regulation have not been clarified. With the aid of simple dynamical models consisting of active peripheral vascular districts (PVDs) fed by ...
Garet Martin - - 2006
In order to examine the acute autonomic response in humans during and immediately after positive pressure-assisted (PPA) breathing, spontaneous cardiac baroreflex (BR) sensitivity was studied through the adaptation of consecutive RR intervals in response to spontaneous systolic blood pressure fluctuations in 11 healthy subjects. The gain (alpha-index) in baroreceptor reflex ...
Sahin Mesut - - 2006
BACKGROUND: Autonomic neuropathy is an important cause of morbidity and mortality in patients with chronic renal failure (CRF) on hemodialysis. Generally, cardiovascular reflex tests are used to determine autonomic neuropathy. Our purpose in this study was to determine the frequency of autonomic neuropathy in patients with CRF on hemodialysis by ...
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