1,720,966 research outputs found
Autonomic control of heart rate: pharmacological and nonpharmacological modulation.
No full textThe evidence of the predictive value of autonomic markers has generated a growing interest for interventions able to influence autonomic control of heart rate. The hypothesis is that an increase in cardiac vagal activity as detected by an increase in heart rate variability (HRV) or baroreflex sensitivity (BRS) may be beneficial in the ischemic heart. Numerous experimental data support the hypothesis that augmenting vagal activity might be protective against lethal ischemic arrhythmias. Among them is the evidence that ventricular fibrillation during acute myocardial ischemia may be largely prevented by electrical stimulation of the right cervical vagus or by pharmacological stimulation of cholinergic receptors with oxotremorine. There is an inherent danger in the so far unwarranted assumption that modification of HRV or BRS translates directly in cardiac protection. This may or may not be the case. It should be remembered that the true target is the improvement in cardiac electrical stability and that BRS or HRV are just markers of autonomic activity. Low dose scopolamine increases HRV in patients with a prior myocardial infarction. This observation, combined with the evidence that elevated cardiac vagal activity during acute myocardial ischemia is antifibrillatory, has generated the hypothesis that scopolamine might be protective after MI. We tested low dose scopolamine in a clinically relevant experimental preparation for sudden death in which other vagomimetic interventions are effective and found that this intervention does indeed increase cardiac vagal markers but has minimal antifibrillatory effects. This is in contrast to exercise training that in the same experimental model had a marked effect on both BRS and HRV and at the same time provided strong protection from ischemic ventricular fibrillation. Thus, based on the current knowledge it seems appropriate to call for caution before attributing excessive importance to changes in "markers" of vagal activity in the absence of clearcut evidence for a causal relation with an antifibrillatory effect
Autonomic modulation during acute myocardial ischemia by low-dose pirenzepine in conscious dogs with a healed myocardial infarction: a comparison with beta-adrenergic blockade.
Full text linkExperimental and clinical evidence documents the ben- eficial effects of blocking sympathetic activity and modulating heart rate to reduce risk for lethal events in ischemic heart disease. Beside -adrenergic receptor blockade, vagal activation is a meaningful ap- proach but not yet easily attainable. Promising results were shown with low-dose atropine and scopolamine, but no follow-up was done because of significant adverse side effects. Pirenzepine is an atropine analogue approved to treat peptic ulcer disease in Europe that is de- void of central actions, which are mostly responsible for anti- muscarinic agents side effects. The vagomimetic action of IV low- dose pirenzepine was studied at rest under control conditions, at rest during acute coronary artery occlusion, and during exercise in con- scious dogs with a healed anterior myocardial infarction (MI). The effects of pirenzepine were then compared, by internal control analy- sis, with those of atenolol (1 mg/kg). Increasing doses of pirenzepine (from 0.01 to 1 mg/kg) were tested in 11 dogs at rest by measuring time and frequency domain heart rate variability (HRV). The most effective dose (0.1 mg/kg) was used in the study. At the most effective dose, pirenzepine increased all measures of time domain HRV by 40–50%. However, the vagomimetic action of pirenzepine was lost during exercise and brief ischemia and no anti-arrhythmic action was observed. Conversely, pirenzepine effectively modulated the heart rate increase during acute ischemia at rest with an effect comparable to that of atenolol. The vagomimetic action of pirenzepine in the acutely ischemic heart supports the possibility that this intervention may be helpful for chronic autonomic modulation in post-MI patients
Is physical training contraindicated in patients with deep vein thrombosis during cardiac rehabilitation?
No full textMetabolic syndrome as a risk factor for deep vein thrombosis after acute cardiac conditions.
No full textThe ALPHA study (T-wave alternans in patients with heart failure): rationale, design and endpoints.
No full textBackground. Sudden death and pump failure are the main causes of death in patients with heart failure. Patients with ischemic and non-ischemic cardiomyopathy are at similar risk of arrhythmic mortality; however, standard non-invasive and invasive tests are not routinely available for non-ischemic patients. T-wave alternans (TWA) has been proposed as a potential marker of susceptibility to ventricular tachycardia-fibrillation in several groups of patients. Methods. The ALPHA study was designed to evaluate the independent predictive value of the measurement of microvolt TWA on the combined occurrence, after 18 months of follow-up, of cardiac death and life-threatening arrhythmias in a population of patients with non-ischemic dilated cardiomyopathy and NYHA class II and III. This is a multicenter prospective observational study. A total of 370 patients, with measurable TWA, will be enrolled during routine follow-up for heart failure treatment; a logbook will be used to collect basic information on the whole screened population. Patients will be enrolled during a 2-year period and will be followed up for 18 months. The primary endpoint of the study will be the combined incidence of cardiac death and life-threatening ventricular arrhythmias. The study will complete recruitment by mid 2004 and report in 2006
Upper extremity deep vein thrombosis and pulmonary embolism after coronary bypass surgery: a case report and preliminary results from a prospective study evaluating patients during cardiac rehabilitation.
No full textAIDS and tuberculosis control programmes: an integrated approach at educational level.
No full textAbstract
In developing countries with a high prevalence of individuals co-infected by human immunodeficiency virus (HIV) and tuberculosis (TB), urgent public health measures should be implemented to prevent the spread of both diseases. This study was performed by a combined acquired immune deficiency syndrome (AIDS)-TB health team with the following aims: 1) to assess knowledge, attitudes and practice towards AIDS; 2) to identify target groups for health education (HE); 3) to evaluate HE impact; 4) to circulate correct information on AIDS and TB through target groups; and 5) to evaluate integration of AIDS and control TB activities. Secondary school students of Arua District, Uganda, participated in a standardized HE session (covering the key-points of AIDS and TB control) preceded by a pretest (multiple choice) questionnaire and followed 3 months later by the same questionnaire (post-test). The impact of HE on AIDS control was evaluated by comparing answers to pre- and post-test questionnaires and its influence on the TB programme by evaluating case-finding performances in the period preceding and following the survey. We analysed 1,478 questionnaires. The results of our study gave information on knowledge about AIDS, identified females and students < 16 yrs of age as good targets for HE, revealed that the impact of HE was significantly associated with improved knowledge, contributed to improved TB case-finding and offered suggestions for the integration of programmes. The survey represented an opportunity to create a stable AIDS/TB health team at district level
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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