45 resultados para mean-periodic function


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With water immersion, gravity is partly eliminated, and the water exerts a pressure on the body surface. Consequently there is a blood volume shift from the periphery to the central circulation, resulting in marked volume loading of the thorax and heart. This paper presents a selection of published literature on water immersion, balneotherapy, aqua exercises, and swimming, in patients with left ventricular dysfunction (LVD) and/or stable chronic heart failure (CHF). Based on exploratory studies, central hemodynamic and neurohumoral responses of aquatic therapies will be illustrated. Major findings are: 1. In LVD and CHF, a positive effect of therapeutic warm-water tub bathing has been observed, which is assumed to be from afterload reduction due to peripheral vasodilatation caused by the warm water. 2. In coronary patients with LVD, at low-level water cycling the heart is working more efficiently than at lowlevel cycling outside of water. 3. In patients with previous extensive myocardial infarction, upright immersion to the neck resulted in temporary pathological increases in mean pulmonary artery pressure (mPAP) and mean pulmonary capillary pressures (mPCP). 4. Additionally, during slow swimming (20-25m/min) the mPAP and/or PCP were higher than during supine cycling outside water at a 100W load. 5. In CHF patients, neck- deep immersion resulted in a decrease or no change in stroke volume. 6. Although patients are hemodynamically compromised, they usually maintain a feeling of well-being during aquatic therapy. Based on these findings, clinical indications for aquatic therapies are proposed and ideas are presented to provoke further research.

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To assess the relationship between renal plasma flow (ERPF) or glomerular filtration rate (GFR) and the levels of norepinephrine (NE) or epinephrine (E) in plasma or urine in the presence of progressive degrees of non-oliguric renal functional impairment, these variables were assessed simultaneously in 18 normal subjects, 72 with parenchymal kidney disease and 14 with essential hypertension. ERPF and GFR were lower (P less than 0.01 to 0.001) in the groups with renal disease (mean +/- SD, 340 +/- 230 and 68 +/- 43 ml/min/1.73 m2, respectively) or essential hypertension (434 +/- 101 and 97 +/- 25 ml/min/1.73 m2) than normal subjects (597 +/- 133 and 118 +/- 14 ml/min/1.73 m2). Plasma and urinary NE and E did not differ significantly among groups and were unrelated with ERPF or GFR (range 4 to 160 ml/min/1.73 m2), except for reduced (P less than 0.001) urinary NE and E excretion in the presence of a GFR less than 20 ml/min. Subgroups with renal disease and a normal (N = 39) or high blood pressure (N = 33) also were comparable in their plasma and urinary NE and E, while ERPF and GFR tended to be lower in hypertensive patients. It is concluded that a chronic reduction in excretory kidney function may have no relevant impact on circulating levels of NE and E per se, although their urinary excretion falls distinctly at the stage of advanced renal failure. These aspects deserve consideration when pathogenetic or diagnostic studies of catecholamines are performed in normotensive or hypertensive patients with impaired kidney function.

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OBJECTIVE: Impaired endothelial function was demonstrated in HIV-infected persons on protease inhibitor (PI)-containing antiretroviral therapy, probably due to altered lipid metabolism. Atazanavir is a PI causing less atherogenic lipoprotein changes. This study determined whether endothelial function improves after switching from other PI to atazanavir. DESIGN: Randomised, observer-blind, treatment-controlled trial. SETTING: Three university-based outpatient clinics. PATIENTS: 39 HIV-infected persons with suppressed viral replication on PI-containing regimens and fasting low-density lipoprotein (LDL)-cholesterol greater than 3 mmol/l. INTERVENTION: Patients were randomly assigned to continue the current PI or change to unboosted atazanavir. MAIN OUTCOME MEASURES: Endpoints at week 24 were endothelial function assessed by flow-mediated dilation (FMD) of the brachial artery, lipid profiles and serum inflammation and oxidative stress parameters. RESULTS: Baseline characteristics and mean FMD values of the two treatment groups were comparable (3.9% (SD 1.8) on atazanavir versus 4.0% (SD 1.5) in controls). After 24 weeks' treatment, FMD decreased to 3.3% (SD 1.4) and 3.4% (SD 1.7), respectively (all p = ns). Total cholesterol improved in both groups (p<0.0001 and p = 0.01, respectively) but changes were more pronounced on atazanavir (p = 0.05, changes between groups). High-density lipoprotein and triglyceride levels improved on atazanavir (p = 0.03 and p = 0.003, respectively) but not in controls. Serum inflammatory and oxidative stress parameters did not change; oxidised LDL improved significantly in the atazanavir group. CONCLUSIONS: The switch from another PI to atazanavir in treatment-experienced patients did not result in improvement of endothelial function despite significantly improved serum lipids. Atherogenic lipid profiles and direct effects of antiretroviral drugs on the endothelium may affect vascular function. Trial registration number: NCT00447070.

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OBJECTIVES: We investigated whether qualitative or quantitative alterations of the endothelial progenitor cell (EPC) pool predict age-related structural vessel wall changes. BACKGROUND: We have previously shown that age-related endothelial dysfunction is accompanied by qualitative rather than quantitative changes of EPCs. Animal studies suggest that impaired EPC functions lead to accelerated arterial intimal thickening. METHODS: Intima-media thickness (IMT) was measured in the common carotid artery in our previously published groups of younger (25 +/- 1 years, n = 20) and older (61 +/- 2 years, n = 20) healthy non-smoking volunteers without arterial hypertension, hypercholesterolemia, and diabetes mellitus. Endothelial progenitor cells (EPCs, KDR(+)/CD34(+) and KDR(+)/CD133(+)) were counted in peripheral blood using flow cytometry. In ex vivo expanded EPCs, the function was determined as chemotaxis to VEGF, proliferation, and survival. RESULTS: We observed thicker IMT in older as compared to younger subjects (0.68 +/- 0.03 mm Vs. 0.48 +/- 0.02 mm, P < 0.001). Importantly, there were significant inverse univariate correlations between IMT, EPC chemotaxis, and survival (r = -0.466 P < 0.05; r = -0.463, P < 0.01). No correlation was observed with numbers of circulating EPCs. Multivariate regression analysis revealed that age, mean arterial pressure and migration of EPCs were independent predictors of IMT (R (2 )= 0.58). CONCLUSION: Impaired EPC function may lead to accelerated vascular remodeling due to chronic impairment of endothelial maintenance.

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Tissue engineering represents an attractive approach for the treatment of congestive heart failure. The influence of the differentiation of myogenic graft for functional recovery is not defined. We engineered a biodegradable skeletal muscle graft (ESMG) tissue and investigated its functional effect after implantation on the epicardium of an infarcted heart segment. ESMGs were synthesized by mixing collagen (2 mg/mL), Matrigel (2 mg/mL), and rat skeletal muscle cells (10(6)). Qualitative and quantitative aspects of ESMGs were optimized. Two weeks following coronary ligation, the animals were randomized in three groups: ESMG glued to the epicardial surface with fibrin (ESMG, n = 7), fibrin alone (fibrin, n = 5), or sham operation (sham, n = 4). Echocardiography, histology, and immunostaining were performed 4 weeks later. A cohesive three-dimensional tissular structure formed in vitro within 1 week. Myoblasts differentiated into randomly oriented myotubes. Four weeks postimplantation, ESMGs were vascularized and invaded by granulation tissue. Mean fractional shortening (FS) was, however, significantly increased in the ESMG group as compared with preimplantation values (42 +/- 6 vs. 33 +/- 5%, P < 0.05) and reached the values of controlled noninfarcted animals (control, n = 5; 45 +/- 3%; not significant). Pre- and postimplantation FS did not change over these 4 weeks in the sham group and the fibrin-treated animals. This study showed that it is possible to improve systolic heart function following myocardial infarction through implantation of differentiated muscle fibers seeded on a gel-type scaffold despite a low rate of survival.

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BACKGROUND: Adult patients with repaired tetralogy of Fallot (rTOF) often have diminished exercise capacity. The primary objective of this study was to examine whether abnormalities of biventricular function play a role in exercise limitation in patients with rTOF. METHODS: This was a retrospective review of 99 adult patients with rTOF. Right ventricular (RV) and left ventricular (LV) function were assessed echocardiographically using the myocardial performance index (MPI). Maximal oxygen consumption (VO(2) Max) was measured during a level 1 cardiopulmonary exercise test. RESULTS: The mean age of the cohort was 34 +/- 11 years (50% females). Although most of the patients reported good functional capacity, the peak Vo(2)max was decreased at 22 +/- 6 mL/kg per minute (66% +/- 13% predicted Vo(2)max for age and sex). The mean RV and LV MPI were 0.30 +/- 0.07 and 0.42 +/- 0.09, respectively. In the multivariate model, higher RV MPI (P = .04) and LV MPI (P = .005) values, representing impaired ventricular function, were associated with diminished Vo(2)max. There was a significant correlation between the RV and LV MPI (r = 0.54, P = .001). CONCLUSIONS: Impairment of RV and LV function, as measured by MPI, is associated with diminished exercise capacity in patients with repaired tetralogy of Fallot. Furthermore, there is a linear relationship between the RV and LV function suggesting that ventricular interactions are contributing to the limited exercise capacity in this group of patients. Strategies aimed at preserving biventricular function or improving adverse ventricular interactions could help to improve functional capacity in these patients.

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OBJECTIVE: To evaluate the effects of a single preoperative dose of steroid on thyroidectomy outcomes. BACKGROUND: Nausea, pain, and voice alteration frequently occur after thyroidectomy. Because steroids effectively reduce nausea and inflammation, a preoperative administration of steroids could improve these thyroidectomy outcomes. METHODS: Seventy-two patients (men = 20, women = 52) undergoing thyroidectomy for benign disease were included in this randomized, controlled, 2 armed (group D: 8 mg dexamethasone, n = 37; group C: 0.9% NaCl, n = 35), double-blinded study (clinical trial number NCT00619086). Anesthesia, surgical procedures, antiemetics, and analgesic treatments were standardized. Nausea (0-3), pain (visual analog scale), antiemetic and analgesic requirements, and digital voice recording were documented before and 4, 8, 16, 24, 36, and 48 hours after surgery. Patients were followed-up 30 days after hospital discharge. RESULTS: Baseline characteristics were similar among the 2 treatment groups. Nausea was pronounced in the first 16 hours postoperatively (scores were <0.3 and 0.8-1.0 for group D and C, respectively (P = 0.005)), and was significantly lower in group D compared with group C during the observation period (P = 0.001). Pain diminished within 48 hours after surgery (visual analog scale 20 and 35 in group D and C, respectively (P = 0.009)). Antiemetic and analgesic requirements were also significantly diminished. Changes in voice mean frequency were less prominent in the dexamethasone group compared with the placebo group (P = 0.015). No steroid-related complications occurred. CONCLUSION: A preoperative single dose of steroid significantly reduced nausea, vomiting, and pain, and improved postoperative voice function within the first 48 hours (most pronounced within 16 hours) after thyroid resection; this strategy should be routinely applied in thyroidectomies.

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STUDY DESIGN: This is an experimental study on an artificial vertebra model and human cadaveric spine. OBJECTIVE: Characterization of polymethylmethacrylate (PMMA) bone cement distribution in the vertebral body as a function of cement viscosity, bone porosity, and injection speed. Identification of relevant parameters for improved cement flow predictability and leak prevention in vertebroplasty. SUMMARY OF BACKGROUND DATA: Vertebroplasty is an efficient procedure to treat vertebral fractures and stabilize osteoporotic bone in the spine. Severe complications result from bone cement leakage into the spinal canal or the vascular system. Cement viscosity has been identified as an important parameter for leak prevention but the influence of bone structure and injection speed remain obscure. METHODS: An artificial vertebra model based on open porous aluminum foam was used to simulate bone of known porosity. Fifty-six vertebroplasties with 4 different starting viscosity levels and 2 different injection speeds were performed on artificial vertebrae of 3 different porosities. A validation on a human cadaveric spine was executed. The experiments were radiographically monitored and the shape of the cement clouds quantitatively described with the 2 indicators circularity and mean cement spreading distance. RESULTS: An increase in circularity and a decrease in mean cement spreading distance was observed with increasing viscosity, with the most striking change occurring between 50 and 100 Pas. Larger pores resulted in significantly reduced circularity and increased mean cement spreading distance whereas the effect of injection speed on the 2 indicators was not significant. CONCLUSION: Viscosity is the key factor for reducing the risk of PMMA cement leakage and it should be adapted to the degree of osteoporosis encountered in each patient. It may be advisable to opt for a higher starting viscosity but to inject the material at a faster rate.

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OBJECTIVE: Recent studies have shown that mechanically unloading a failing heart may induce reverse remodeling and functional improvement. However, these benefits may be balanced by an unloading-related remodeling including myocardial atrophy that might lead to decrease in function. Using a model of heterotopic heart transplantation, we aimed to characterize the myocardial changes induced by long-term unloading. MATERIAL AND METHODS: Macroscopic as well as cellular and functional changes were followed in normal hearts unloaded for a 3-month period. Microscopic parameters were evaluated with stereologic methodology. Myocardial contractile function was quantified with a Langendorff isolated, perfused heart technique. RESULTS: Atrophy was macroscopically obvious and accompanied by a 67% reduction of the myocyte volume and a 43% reduction of the interstitial tissue volume, thus accounting for a shift of the myocyte/connective tissue ratio in favor of noncontractile tissue. The absolute number of cardiomyocyte nuclei decreased from 64.7 +/- 5.1 x 10(7) in controls to 22.6 +/- 3.7 x 10(7) (30 days) and 21.6 +/- 3.1 x 10(7) (90 days) after unloading (P < .05). The numeric nucleic density in the unloaded myocardium, as well as the mean cardiomyocyte volume per cardiomyocyte nucleus, remained constant throughout the 90 days of observation. Functional data indicated an increase in ventricular stiffness, although contractile function was preserved, as confirmed by unaltered maximal developed pressure and increased contractility (maximum rate of left ventricular pressure development) and relaxation (minimum rate of left ventricular pressure development). CONCLUSION: Atrophic remodeling involves both the myocyte and interstitial tissue compartment. These data suggest that although there is decreased myocardial volume and increased stiffness, contractile capacity is preserved in the long-term unloaded heart.

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The aim of the present study was to investigate prefrontal brain function and cognitive response control in patients with personality disorders who either suffered or did not suffer from psychopathology related to attention deficit hyperactivity disorder (ADHD) during childhood. For this purpose, 36 psychiatric out-patients with personality disorders--24 of whom showed ADHD-related psychopathology during childhood assessed by the German short form of the Wender Utah Rating Scale--and 24 healthy controls were investigated electrophysiologically by means of a cued Go-NoGo task (Continuous Performance Test). Topographical analyses were conducted to individually quantify the NoGo anteriorisation (NGA), a neurophysiological correlate of prefrontal response control that has been suggested to reflect activation of the anterior cingulate cortex. ADHD patients exhibited a significantly reduced mean NGA and diminished amplitudes of the Global Field Power, as well as a reduced increase of fronto-central P300 amplitudes, in NoGo-trials compared with the healthy controls, whereas patients with personality disorders alone did not differ from the control group in any of the electrophysiological parameters. The results indicate that ADHD-related psychopathology is associated with prefrontal brain dysfunction, probably related to processes of response inhibition and/or cognitive response control.

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OBJECTIVE This study tested the hypotheses that intermittent coronary sinus occlusion (iCSO) reduces myocardial ischaemia, and that the amount of ischaemia reduction is related to coronary collateral function. DESIGN Prospective case-control study with intraindividual comparison of myocardial ischaemia during two 2-min coronary artery balloon occlusions with and without simultaneous iCSO by a balloon-tipped catheter. SETTING University Hospital. PATIENTS 35 patients with chronic stable coronary artery disease. INTERVENTION 2-min iCSO. MAIN OUTCOME MEASURES Myocardial ischaemia as assessed by intracoronary (i.c.) ECG ST shift at 2 min of coronary artery balloon occlusion. Collateral flow index (CFI) without iCSO, that is, the ratio between mean distal coronary occlusive (Poccl) and mean aortic pressure (Pao) both minus central venous pressure. RESULTS I.c. ECG ST segment shift (elevation in all) at the end of the procedure with iCSO versus without iCSO was 1.33±1.25 mV versus 1.85±1.45 mV, p<0.0001. Regression analysis showed that the degree of i.c. ECG ST shift reduction during iCSO was related to CFI, best fitting a Lorentzian function (r(2)=0.61). Ischaemia reduction with iCSO was greatest at a CFI of 0.05-0.20, whereas in the low and high CFI range the effect of iCSO was absent. CONCLUSIONS ICSO reduces myocardial ischaemia in patients with chronic coronary artery disease. Ischaemia reduction by iCSO depends on coronary collateral function. A minimal degree of collateral function is necessary to render iCSO effective. ICSO cannot manifest an effect when collateral function prevents ischaemia in the first place.

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OBJECTIVES Non-steroidal anti-inflammatory drugs (NSAIDs) may cause kidney damage. This study assessed the impact of prolonged NSAID exposure on renal function in a large rheumatoid arthritis (RA) patient cohort. METHODS Renal function was prospectively followed between 1996 and 2007 in 4101 RA patients with multilevel mixed models for longitudinal data over a mean period of 3.2 years. Among the 2739 'NSAID users' were 1290 patients treated with cyclooxygenase type 2 selective NSAIDs, while 1362 subjects were 'NSAID naive'. Primary outcome was the estimated glomerular filtration rate according to the Cockroft-Gault formula (eGFRCG), and secondary the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration formula equations and serum creatinine concentrations. In sensitivity analyses, NSAID dosing effects were compared for patients with NSAID registration in ≤/>50%, ≤/>80% or ≤/>90% of assessments. FINDINGS In patients with baseline eGFRCG >30 mL/min, eGFRCG evolved without significant differences over time between 'NSAID users' (mean change in eGFRCG -0.87 mL/min/year, 95% CI -1.15 to -0.59) and 'NSAID naive' (-0.67 mL/min/year, 95% CI -1.26 to -0.09, p=0.63). In a multivariate Cox regression analysis adjusted for significant confounders age, sex, body mass index, arterial hypertension, heart disease and for other insignificant factors, NSAIDs were an independent predictor for accelerated renal function decline only in patients with advanced baseline renal impairment (eGFRCG <30 mL/min). Analyses with secondary outcomes and sensitivity analyses confirmed these results. CONCLUSIONS NSAIDs had no negative impact on renal function estimates but in patients with advanced renal impairment.

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OBJECTIVE To expand the limited information on the prognostic impact of quantitatively obtained collateral function in patients with coronary artery disease (CAD) and to estimate causality of such a relation. DESIGN Prospective cohort study with long-term observation of clinical outcome. SETTING University Hospital. PATIENTS One thousand one hundred and eighty-one patients with chronic stable CAD undergoing 1771 quantitative, coronary pressure-derived collateral flow index measurements, as obtained during a 1-min coronary balloon occlusion (CFI is the ratio between mean distal coronary occlusive pressure and mean aortic pressure both subtracted by central venous pressure). Subgroup of 152 patients included in randomised trials on the longitudinal effect of different arteriogenic protocols on CFI. INTERVENTIONS Collection of long-term follow-up information on clinical outcome. MAIN OUTCOME MEASURES All-cause mortality and major adverse cardiac events. RESULTS Cumulative 15-year survival rate was 48% in patients with CFI<0.25 and 65% in the group with CFI≥0.25 (p=0.0057). Cumulative 10-year survival rate was 75% in patients without arteriogenic therapy and 88% (p=0.0482) in the group with arteriogenic therapy and showing a significant increase in CFI at follow-up. By proportional hazard analysis, the following variables predicted increased all-cause mortality: age, low CFI, left ventricular end-diastolic pressure and number of vessels with CAD. CONCLUSIONS A well-functioning coronary collateral circulation independently predicts lowered mortality in patients with chronic CAD. This relation appears to be causal, because augmented collateral function by arteriogenic therapy is associated with prolonged survival.

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Objective To evaluate the effect of heart rate reduction by ivabradine on coronary collateral function in patients with chronic stable coronary artery disease (CAD). Methods This was a prospective randomised placebo-controlled monocentre trial in a university hospital setting. 46 patients with chronic stable CAD received placebo (n=23) or ivabradine (n=23) for the duration of 6 months. The main outcome measure was collateral flow index (CFI) as obtained during a 1 min coronary artery balloon occlusion at study inclusion (baseline) and at the 6-month follow-up examination. CFI is the ratio between simultaneously recorded mean coronary occlusive pressure divided by mean aortic pressure both subtracted by mean central venous pressure. Results During follow-up, heart rate changed by +0.2±7.8 beats/min in the placebo group, and by –8.1±11.6 beats/min in the ivabradine group (p=0.0089). In the placebo group, CFI decreased from 0.140±0.097 at baseline to 0.109±0.067 at follow-up (p=0.12); it increased from 0.107±0.077 at baseline to 0.152±0.090 at follow-up in the ivabradine group (p=0.0461). The difference in CFI between the 6-month follow-up and baseline examination amounted to −0.031±0.090 in the placebo group and to +0.040±0.094 in the ivabradine group (p=0.0113). Conclusions Heart rate reduction by ivabradine appears to have a positive effect on coronary collateral function in patients with chronic stable CAD.

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BACKGROUND Small airways disease is a hallmark in adults with persistent asthma, but little is known about small airways function in children with mild asthma and normal spirometry. We assessed ventilation heterogeneity, a marker of small airways function, with an easy tidal breath single-breath washout (SBW) technique in school-aged children with mild asthma and normal FEV1 and healthy age-matched control subjects. METHODS The primary outcome was the double-tracer gas phase III slope (SDTG), an index of ventilation heterogeneity in acinar airways derived from the tidal double-tracer gas SBW test. The second outcome was the nitrogen phase III slope (SN2), an index of global ventilation heterogeneity derived from the tidal nitrogen SBW test using pure oxygen. Triplicate SBW and spirometry tests were performed in healthy children (n = 35) and children with asthma (n = 31) at baseline and in children with asthma after bronchodilation. RESULTS Acinar (SDTG) but not global (SN2) ventilation heterogeneity was significantly increased in asthma despite normal FEV1. Of the 31 children with asthma, abnormal results were found for SDTG (≤ -2 z scores) in 11; forced expiratory flow, midexpiratory phase (FEF25%-75%) in three; and FEV1 in zero. After bronchodilation, SDTG, SN2, FEF25%-75%, and FEV1 significantly changed (mean [95% CI] change from baseline, 36% [15%-56%], 38% [18%-58%], 17% [9-25%], and 6% [3%-9%], respectively). CONCLUSIONS Abnormal acinar ventilation heterogeneity in one-third of the children suggests that small airways disease may be present despite rare and mild asthma symptoms and normal spirometry. The easy tidal SBW technique has considerable potential as a clinical and research outcome in children with asthma.