Cardiorespiratory requirements of the 6-min walk test in patients with left ventricular systolic disfunction and no major structural heart disease

The six-minute walk test (6-MWT) is widely used to assess functional status in patients with chronic heart failure (CHF). The aims of the present study were: (1) to compare metabolic gas exchange during the 6-MWT in older patients with left ventricular systolic dysfunction (LVSD) and in breathless patients with no major structural heart disease (MSHD); (2) to determine the exercise intensity of the 6-MWT relative to peak oxygen uptake; (3) to establish the accuracy and reproducibility of the Metamax 3B ergospirometer during an incremental workload. Twenty four older patients with LVSD (19 male; age 76 ± 5 years; BMI 27 ± 4), and 18 patients with no MSHD (12 male; age 75 ± 8 years; BMI 27 ± 4) attended on consecutive days at the same time. Patients completed a 6-MWT with metabolic gas exchange measurements using the Metamax 3B portable ergospirometer, and an incremental cycle ergometry test using both the Metamax 3B and Oxycon Pro metabolic cart. Patients returned and performed a second 6-MWT and an incremental treadmill test, metabolic gas exchange was measured with the Metamax 3B. In patients with LVSD, the 6-MWT was performed at a higher fraction of maximal exercise capacity (p = 0.02). The 6-MWT was performed below the anaerobic threshold in patients with LVSD (83 %) and in patients with no MSHD (61 %). The Metamax 3B showed satisfactory to high accuracy at 10 W and 20 W in patients with LVSD (r = 0.77 - 0.97, p < 0.05), and no MSHD (r = 0.76 - 0.94, p < 0.05). Metabolic gas exchange variables measured during the 6-MWT showed satisfactory to high day-to-day reproducibility in patients with LVSD (ICC = 0.75 - 0.98), but a higher variability was evident in participants with no MSHD (ICC = 0.62 - 0.97). The Metamax 3B portable ergospirometer is an accurate and reproducible device during submaximal, fixed rate exercise in older patients with LVSD and no MSHD. In elderly patients with LVSD and no MSHD, the 6-MWT should not be considered a maximal test of exercise capacity but rather a test of submaximal exercise performance. Our study demonstrates that the 6-MWT takes place at a higher proportion of peak oxygen uptake in patients with LVSD compared to those with no MSHD, and may be one reason why fatigue is a more prominent symptom in these patients

The lived experiences of people diagnosed with multiple sclerosis in relation to exercise

The purpose of this study was to examine the lived experiences of people diagnosed with Multiple Sclerosis (MS). Seven active exercisers with MS participated in semi-structured interviews regarding their exercise experiences since diagnosis. Data were analysed using Interpretative Phenomenological Analysis (IPA; Smith Osborn, 2003). Interpretive Phenomenological Analysis. The results and interpretations of narratives revealed a number of functional limitations due to the severity of MS symptoms, which were found to have a major effect on the ability of the participants to exercise. Furthermore, psychological problems and the heightened behavioural adjustments to the progressive disability led to re-appraisal of ability to exercise. Previous, relevant exercise experience made participants more determined to continue to be able to exercise after diagnosis. The wider exercise experience narratives were related to concerns about safety, dependability on others to overcome the challenges, and potential environmental hazards. The loss of spontaneous opportunities to exercise because of these actual and perceived barriers was key to this population. This research highlighted the need to rethink the health and social service arrangements in relation to exercise provision for individuals with MS

Changes in body composition in patients with left ventricular systolic dysfunction initiated on beta-blocker therapy

Background: Increasing body mass index, cholesterol and body fat are associated with a better prognosis in patients with left ventricular systolic dysfunction (LVSD). Beta-blocker usage is associated with changes in body composition and increased body fat. The present study investigated 12-month changes in body composition in patients with LVSD initiated on beta-blocker therapy. Methods: The relation between beta-blocker use and body composition was evaluated in 91 patients (75% male) with LVSD. Body composition was assessed by bioelectrical impedance. Results: Seventeen patients died during the study period. There was no statistical difference among beta-blocker usage, beta-blocker type, or changes in body fat, basal metabolic rate, impedance, fat-free mass, fat mass and total body water. There were no significant differences between any of these measures and beta-blocker usage. Conclusion: After 12 months, changes in body composition were not found to be influenced by initiation of beta-blocker therapy in patients with LVSD. © 2007 Pulsus Group Inc. All rights reserved

Prognostic value of the 6 min walk test and self-perceived symptom severity in older patients with chronic heart failure

Background: The 6 min walk test (6-MWT) is a simple and popular test for evaluating functional status in patients with chronic heart failure (CHF). However, the prognostic value of the 6-MWT in a large, representative sample of CHF patients, and in patients with different degrees of left ventricular systolic dysfunction (LVSD) remains unclear. Methods and results: Of an initial population of 1592 patients, 212 died representing a crude death rate of 13.3%. In surviving patients, the median time to follow-up period was 36.6 months [inter-quartile range (IQR) 28-45 months]. Five variables remained independent predictors of all-cause mortality; decreasing 6-MWT distance, self-perceived signs of breathlessness at night (SOBAN), beta-blocker usage, elevated log NT-proBNP, and reduced haemoglobin concentration. We also dichotomized our analysis by LVSD status (≤mild LVSD or > mild LVSD). For patients with > mild LVSD, 6-MWT remained an important prognostic indicator but not in patients with ≤mild LVSD. Conclusion: The 6-MWT is an important independent predictor of mortality in CHF patients, and this was especially evident in patients with > mild LVSD. The 6-MWT provides little prognostic utility in patients with ≤mild LVSD. While log NT-proBNP was the most potent independent predictor, an additive prognostic effect was evident with the additional selection of 6-MWT. Patients' self-perceived symptoms, especially SOBAN was an independent predictor of mortality in our patients. © The European Society of Cardiology 2007. All rights reserved

The Role of Platelet-Activating Factor in Mesangial Pathophysiology

Platelet-activating factor (PAF) is a powerful proinflammatory mediator that displays an exceedingly diverse spectrum of biological effects. Importantly, PAF is shown to participate in a broad range of pathologic conditions. This review focuses on the role that PAF plays specifically in the pathophysiology of the kidney, the organ that is both a source and a target of PAF. Renal mesangial cells are responsible for glomerular PAF generation and, ultimately, are the victims of its excessive production. Mesangial pathology is widely acknowledged to reflect glomerular damage, which culminates in glomerulosclerosis and proteinuria. Therefore, modulation of mesangial cell responses would offer a pathophysiology-based therapeutic approach to prevent glomerular injury. However, the currently available therapeutic modalities do not allow for targeted intervention into these processes. A more profound understanding of the mechanisms that govern PAF metabolism and signaling in mesangial cells is important, because it could facilitate the quest for improved therapies for renal patients on the basis of PAF as a drug target