Search Results
Results 701 - 750 of 1270
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Azuaje F - - 1999
Coronary heart disease is a multifactorial disease and it remains the most common cause of death in many countries. Heart rate variability has been used for non-invasive measurement of parasympathetic activity and prediction of cardiac death. Patterns of heart rate variability associated with respiratory sinus arrhythmia have recently been considered ...
Lanza G A - - 1999
The aim of this study was to investigate the usefulness of heart rate variability (HRV) in predicting cardiac mortality in patients with a recent acute myocardial infarction at high risk of events. Time- and frequency-domain HRV was assessed on 24-hour pre-discharge Holter recording of 81 patients (mean age 65 +/- ...
Petretta M - - 1999
BACKGROUND: Analysis of heart rate variability (HRV) is a valuable noninvasive method for quantifying autonomic cardiac control in humans and has been utilized during dipyridamole echocardiographic test to differentiate positive from negative test results. HYPOTHESIS: We aimed to evaluate, by means of HRV analysis, the influence of the angiographic severity ...
Hartmann F - - 1999
OBJECTIVE: To assess presynaptic function of cardiac autonomic innervation in patients with advanced congestive heart failure using positron emission tomography (PET) and the recently developed radiolabelled catecholamine analogue carbon-11 hydroxyephedrine (HED) as a marker for neuronal catecholamine uptake function. DESIGN AND PATIENTS: 29 patients suffering from dilated cardiomyopathy with moderate ...
Tygesen H - - 1999
Beta-Blockers reduce mortality in patients with congestive heart failure and a proposed mechanism has been changes of autonomic tone. Heart rate variability is a non-invasive tool to estimate cardiac autonomic tone. The aim was to study changes of heart rate variability in patients with congestive heart failure on placebo, on ...
Weber F - - 1999
AIMS: Determination of the influence of therapy with bisoprolol and nifedipine on the heart rate variability of patients from the Total Ischemic Burden Bisoprolol Study and examination of the prognostic value. METHODS AND RESULTS: Four hundred and twenty-two patients with stable angina were included. The heart rate variability was determined ...
Stein P K - - 1999
Indices of heart rate variability (HRV) provide a window onto autonomic modulation of the heart. HRV indices, determined in either the time or frequency domain, are closely related and reflect parasympathetic, mixed sympathetic, and parasympathetic and circadian rhythms. In population studies, decreased HRV has had predictive value for mortality among ...
Kerut E K - - 1999
Analysis of heart rate variability (HRV) permits an assessment of sympathetic and parasympathetic activity from EKG recordings. Analysis of HRV may be performed in both the time and frequency domain by the application of mathematical principles of signal processing. HRV demonstrates abnormalities in myocardial infarction, sudden death, heart failure, autonomic ...
Dreiseitl S - - 1999
This paper evaluates the variable selection performed by several machine-learning techniques on a myocardial infarction data set. The focus of this work is to determine which of 43 input variables are considered relevant for prediction of myocardial infarction. The algorithms investigated were logistic regression (with stepwise, forward, and backward selection), ...
Del Greco M - - 1999
ST-elevation acute myocardial ischemia occurred after phenylephrine infusion in a patient with severe coronary artery disease and recent myocardial infarction. The subsequent administration of nitroglycerin led to a vasovagal response with symptomatic hypotension and bradycardia. During myocardial ischemia, heart-rate variability and baroreflex sensitivity analysis described a marked activation of sympathetic ...
Lanza G A - - 1998
A low heart rate variability (HRV) has been shown to be a powerful predictor of cardiac events in patients surviving an acute myocardial infarction (MI), but it is not clear yet which among the HRV parameters has the best predictive value. Time domain and frequency domain HRV was assessed on ...
Napier L D - - 1998
The vagotonic effect of chronic morphine on the parasympathetic control of the heart was examined in dogs treated with morphine for 2 wk. Because normal vagal function is critical to myocardial stability, the study was conducted to evaluate for potential impairments following chronic vagal stimulation. The hypothesis that persistent vagal ...
Scalvini S - - 1998
Autonomic dysfunction seems to be involved in the progression and prognosis of congestive heart failure. Measurement of heart rate variability (HRV) provides a noninvasive method to obtain reliable and reproducible information on autonomic modulation of heart rate, but there is a difficulty in using HRV as a quantitative estimate of ...
Calvert C A - - 1998
Heart rate variability (HRV), usually performed from 24 hour ambulatory ECG recordings, measures the variability of the heart rate. Alterations in autonomic balance and baroreceptor function, increased plasma norepinephrine levels, and reduced HRV have been associated with progressive myocardial failure. Not only has reduced HRV been associated with the degree ...
Láng E - - 1998
The purpose of this study was to contribute to the improvement of stratification of post-myocardial infarction patients at increased risk of malignant ventricular arrhythmia (MVA). Power spectral analysis of heart period variability (HPV) was used as a non-invasive tool to assess cardiac autonomic control. Three groups were used: (1) post-myocardial ...
Nolan J J General Infirmary and St James's University Hospital, Leeds, - - 1998
Patients with chronic heart failure (CHF) have a continuing high mortality. Autonomic dysfunction may play an important role in the pathophysiology of cardiac death in CHF. UK-HEART examined the value of heart rate variability (HRV) measures as independent predictors of death in CHF. In a prospective study powered for mortality, ...
Fauchier L - - 1998
Heart rate variability is a noninvasive indicator of autonomic nervous system activity. The role of the autonomic nervous system in the genesis of atrial or ventricular arrhythmias is now well established. Little is known about the effects of flecainide on heart rate variability in patients with normal heart structure, the ...
Kurata C - - 1998
It is assumed that the low-frequency power (LF) of heart rate variability (HRV) increases with progress of congestive heart failure (CHF), therefore positively correlating with cardiac 123I-metaiodobenzylguanidine (MIBG) washout. It is demonstrated here that HRV, including normalized LF, correlated inversely with MIBG washout and positively with the ratio of heart-to-mediastinum ...
Wittling W - - 1998
Hemisphere asymmetry in sympathetic control of myocardial performance was studied in healthy human subjects using lateralized film presentation for selective sensory stimulation of the hemispheres and impedance cardiography for the evaluation of cardiac output, systolic time intervals and myocardial contractility. Results revealed a clear and consistent right hemisphere predominance in ...
Stys A - - 1998
Heart rate variability (HRV) has become a popular method for the studies of physiologic mechanisms responsible for the control of heart rate fluctuations, in which the autonomic nervous system appears to play a primary role. Depression of HRV has been observed in many clinical scenarios, including autonomic neuropathy, heart transplantation, ...
Rolf N - - 1998
The coronary circulation is subject to modulation by the autonomic nervous system. Thus, sympathetic stimulation causes coronary vasodilation in healthy humans, whereas stenotic coronary arteries react by vasoconstriction in response to sympathetic stimulation. It is for this reason that experimental studies and clinical evidence revealed beneficial effects of a blockade ...
Linden D - - 1998
INTRODUCTION: Clinically relevant autonomic disturbances have been reported for respirator-dependent ALS patients while subclinical involvement may be present in the early course. METHODS: Eighteen patients with early-stage ALS and 18 age-matched controls were studied by means of standard autonomic tests (heart off + response to deep breathing and tilt-table testing), ...
Momose M - - 1998
The aim of this study was to determine whether sympathetic imbalance in congenital long QT syndrome (LQTS) can be identified by cardiac sympathetic neuronal dysinnervation. 123I-metaiodobenzylguanidine (MIBG) is a tracer of the norepinephrine analogue which reflects the regional innervation and norepinephrine kinetics in cardiac sympathetic nerves. Sixteen patients with LQTS, ...
Grassi G - - 1998
To review the sympathetic abnormalities occurring in heart failure, their pathophysiological importance and clinical relevance, and the effects of drug treatment, with particular reference to calcium antagonists. Indirect and direct approaches to study sympathetic function in humans have documented conclusively that sympathetic activation represents a hallmark of cardiac failure syndrome. ...
Dávila D F - - 1998
The autonomic nervous system is abnormal in patients with advanced Chagas' heart disease. Most researchers consider these autonomic abnormalities as primary, specific and irreversible. However, when and why these abnormalities appear in the natural history of Chagas' disease, is still the subject of intense controversy. Recent morphological and functional studies ...
Fauchier L - - 1998
Frequency-domain analysis of heart rate variability provides information about influences of autonomic nervous system on the heart and can be measured on short-term or long-term electrocardiogram recording. We compared heart rate variability on 24 h electrocardiogram recording with measurements of heart rate variability over shorter periods of 1 h and ...
Castellanos A - - 1998
Analysis of heart rate variability in patients with inappropriate sinus tachycardia showed a 24-hour decrease in all temporal and spectral indexes, even after attempted correction to a rate of 75 beats/min. This may have resulted from a global decrease in parasympathetic activity or from a rapid sinus rate produced by ...
Kline K P - - 1998
T-Wave Amplitude (TWA) has been suggested as an indicator of sympathetic influence on myocardial performance, but critics have argued that TWA is confounded by parasympathetic influence or that it is a non-specific feature of tachycardia. To help clarify the issue, we examined TWA as a function of parasympathetic activity, using ...
Fisher J C - - 1998
Clinical correlation of frequency-domain characteristics of electrocardiograms with specific disease entities of thousands of patients has produced a simple, noninvasive diagnostic system capable of detecting many cardiac abnormalities with specificity and sensitivity exceeding 90%. This system, a proprietary product called CUPID, is now undergoing clinical trials in Europe, South America, ...
Vaage-Nilsen M - - 1998
Because decreased heart rate variability measured after an acute myocardial infarction (AMI) has been demonstrated to predict subsequent mortality and sudden death, and an efficacy analysis of the Danish Verapamil Infarction Trial II (DAVIT II) demonstrated that long-term postinfarction treatment with verapamil significantly reduced sudden death, the aim of the ...
Julius S - - 1998
Increased sympathetic tone is found in about 30% of patients with hypertension. This abnormality is closely associated with the metabolic syndrome of dyslipidaemia and hyperinsulinaemia. In this short review we discuss the mechanisms by which sympathetic over-activity could cause the metabolic syndrome. Sympathetic stimulation enhances cardiac and vascular hypertrophy. Left ...
Priola D V - - 1998
The present experiments were performed to examine the capability of the intrinsic cardiac nerves (ICN) to modify cardiac performance in the resting chronic, conscious dog. Control and cardiac-denervated dogs were instrumented for recording of left atrial (LA) and ventricular (LV) contractility, heart rate, and atrioventricular (AV) conduction time. Acetylcholine (ACh) ...
Ceconi C - - 1998
The development of profound autonomic dysfunction and of neuroendocrine activation characterizes and possibly contributes to the progression of heart disease to congestive heart failure. Sympathetic activation is a generalized process and the proposed mechanisms for neurohumoral activation include decreased input from excitatory afferences and increased input from excitatory chemoceptors and ...
Leung J M - - 1998
PURPOSE: To compare the simultaneous haemodynamic effects, sympathetic activation and cardiac risks associated with desflurane used in a balanced technique, with those of isoflurane anaesthesia. METHODS: A prospective, randomized, open label study was conducted at a University medical centre. Forty patients undergoing major non-cardiac surgery were randomized to receive either ...
Schwartz P J - - 1998
The knowledge progressively accumulated on the relation between changes in autonomic activity and cardiac mortality, particularly in the setting of acute myocardial ischaemia, has turned during the last decade toward the potential prognostic value of markers of autonomic activity. Two of these markers, heart rate variability and baroreflex sensitivity, have ...
Pitzalis M V - - 1998
Modifications in heart rate variability (HRV) parameters occur after acute myocardial infarction. The aim of this study was to evaluate the trend of HRV change during the acute phase and the first month after myocardial infarction, and establish whether they were affected by the anterior or inferior location of the ...
Pinar E - - 1998
In patients with previous myocardial infarction (MI), depressed heart rate variability (HRV) may reflect a reduction in vagal activity and lead to cardiac electrical instability. Interventions designed to increase HRV may be of clinical interest. Data on the effects of calcium antagonists on HRV in post-MI patients are very limited. ...
Iwasa K - - 1998
We studied myocardial 123I-metaiodobenzylguanidine (MIBG) accumulation in 12 patients with Parkinson's disease (PD). MIBG is an analog of norepinephrine (NE) and a tracer for sympathetic neuron integrity and function. MIBG uptake of the myocardium was significantly lower in PD than in controls. The heart to mediastinum ratio (H/M) was calculated ...
Osterhues H H - - 1998
OBJECTIVES: It is not known whether the improvement of myocardial perfusion by percutaneous transluminal coronary angioplasty (PTCA) is followed by a response of the autonomic nervous system depending on the recovery of the myocardium. In this study we investigated changes of heart rate variability parameters in patients before and after ...
Shiigi T - - 1998
The aim of the study was to assess the relationship between changes in heart rate variability (HRV) and parameters of neuroendocrine activation in patients with various levels of left ventricular dysfunction. Measurements of HRV, plasma norepinephrine (PNE), and plasma atrial natriuretic peptide (ANP) were performed in 17 age- and gender-matched ...
Bonaduce D - - 1998
PURPOSE: We aimed to evaluate in a longitudinal study the effect of intensive training on cardiac autonomic control in athletes using 24-h heart rate variability analysis. METHODS: Time and frequency domain measures of heart rate variability were calculated from 24-h Holter monitoring in 15 high level bicyclists (mean age 21 ...
Miwa K - - 1998
BACKGROUND: Autonomic nervous discharge has been implicated in the pathogenesis of coronary artery spasm. METHODS: Cardiac autonomic nervous activities were evaluated from the power of the low-frequency and the high-frequency spectral components of heart rate variability with Holter monitoring in 18 patients with nocturnal variant angina. Samples during the first ...
Ishise H - - 1998
To elucidate the time course of sympathovagal balance and its relationship to left ventricular function in heart failure, we serially evaluated left ventricular contractility and relaxation and autonomic tone in 11 conscious dogs with tachycardia-induced heart failure. We determined a dynamic map of sympathetic and parasympathetic modulation by power spectral ...
Braverman D L - - 1998
Reflex sympathetic dystrophy is a mysterious entity with unclear pathogenesis. The diagnosis is largely clinical and based on signs and symptoms of pain and vasomotor dysfunction. Treatment is a challenge because the underlying mechanism remains unknown. Our patient is a 75-year-old woman 2 years after left total knee replacement who ...
La Rovere M T - - 1998
BACKGROUND: Experimental evidence suggests that autonomic markers such as heart-rate variability and baroreflex sensitivity (BRS) may contribute to postinfarction risk stratification. There are clinical data to support this concept for heart-rate variability. The main objective of the ATRAMI study was to provide prospective data on the additional and independent prognostic ...
Elvan A - - 1998
BACKGROUND: Because efferent autonomic pathways to the right ventricle (RV) differ from the efferent autonomic projections to the left ventricle (LV), we assessed the effects of RV infarction on this innervation. METHODS AND RESULTS: We measured the ventricular effective refractory period (ERP) shortening in response to bilateral ansae subclaviae stimulation ...
Maestri R - - 1998
OBJECTIVES: This study sought to compare, in post-myocardial infarction patients, baroreflex sensitivity (BRS) measured by the phenylephrine method (Phe-BRS) with that estimated by the Robbe (Robbe-BRS) and Pagani (alpha-low frequency [LF] and alpha-high frequency [HF]) spectral techniques. BACKGROUND: BRS assessed by Phe-BRS has been shown to be of prognostic value ...
Monge-Argilés J A - - 1998
OBJECTIVES: Multiple sclerosis (MS) frequently causes disturbances of autonomic functions. Cardiovascular dysautonomia has been studied by classic autonomic tests and, recently, by heart rate variability analysis in some isolated periods. Multiple authors recommended performing heart rate variability analysis with a 24 h ECG recording to increase its sensitivity. MATERIAL AND ...
Voss A - - 1998
A multiparametric heart rate variability analysis was performed to prove if combined heart rate variability (HRV) measures of different domains improve the result of risk stratification in patients after myocardial infarction. In this study, standard time domain, frequency domain and non-linear dynamics measures of HRV assessment were applied to 572 ...
Malik M - - 1998
Heart rate variability is a recognized tool for the estimation of cardiac autonomic modulations. Recently, several studies have advanced the field of heart rate variability in three areas: 1) in technical modes of electrocardiogram processing and heart rate variability assessment, 2) in physiologic understanding and interpretation, and 3) in clinical ...
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