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Biomedical subjects

F Pedersen

Publications and source records attributed to F Pedersen.

At least 19 recordsLinked to original sources
PubMed2004

Diagnostic and prognostic evaluation of left ventricular systolic heart failure by plasma N-terminal pro-brain natriuretic peptide concentrations in a large sample of the general population.

OBJECTIVE: To evaluate N-terminal pro-brain natriuretic peptide (NT-proBNP) as a diagnostic and prognostic marker for systolic heart failure in the general population. DESIGN: Study participants, randomly selected to be representative of the background population, filled in a heart failure questionnaire and underwent pulse and blood pressure measurements, electrocardiography, echocardiography, and blood sampling and were followed up for a median (range) period of 805 (60-1171) days. SETTING: Participants were recruited from four randomly selected general practitioners and were examined in a Copenhagen university hospital. PATIENTS: 382 women and 290 men in four age groups (50-59 (n = 174); 60-69 (n = 204); 70-79 (n = 174); > or = 80 years (n = 120)). MAIN OUTCOME MEASURES: Value of NT-proBNP in evaluating patients with symptoms of heart failure and impaired left ventricular (LV) systolic function; prognostic value of NT-proBNP for mortality and hospital admissions. RESULTS: In 38 (5.6%) participants LV ejection fraction (LVEF) was < or = 40%. NT-proBNP identified patients with symptoms of heart failure and LVEF < or = 40% with a sensitivity of 0.92, a specificity of 0.86, positive and negative predictive values of 0.11 and 1.00, and area under the curve of 0.94. NT-proBNP was the strongest independent predictor of mortality (hazard ratio (HR) = 5.70, p < 0.0001), hospital admissions for heart failure (HR = 13.83, p < 0.0001), and other cardiac admissions (HR = 3.69, p < 0.0001). Mortality (26 v 6, p = 0.0003), heart failure admissions (18 v 2, p = 0.0002), and admissions for other cardiac causes (44 v 13, p < 0.0001) were significantly higher in patients with NT-proBNP above the study median (32.5 pmol/l). CONCLUSIONS: Measurement of NT-proBNP may be useful as a screening tool for systolic heart failure in the general population.

Aged↗
PubMed2003

Prevalence of impaired left ventricular systolic function and heart failure in a middle aged and elderly urban population segment of Copenhagen.

OBJECTIVE: To assess the prevalence of impaired left ventricular systolic function and manifest heart failure in a general population aged 50-89 years. DESIGN: In this cross sectional survey, participants filled in a heart failure questionnaire. ECG, blood tests, and echocardiography were performed. SETTING: The study population was recruited from general practitioners situated in the same urban area and examined in a university hospital in Copenhagen, Denmark. PARTICIPANTS: 764 participants (432 women and 332 men, median (SD) age 66 (11) years) participated. The study population was stratified to include a minimum of 150 persons in each age decade. MAIN OUTCOME MEASURES: Prevalence of impaired systolic function and manifest heart failure. RESULTS: The prevalence of systolic dysfunction (left ventricular ejection fraction < or = 40%) was more than twice as high among men (7.6%) as among women (2.6%). In the male population systolic heart failure (left ventricular ejection fraction < or = 40% and symptoms) was found in 1.8% of the 50-59 years age group and approximately doubled for each age decade to reach 13.9% in octogenarians. Among women systolic dysfunction increased from 0.8% to 4.3% in the same age groups. Asymptomatic cases accounted for 44.0% of all cases of systolic dysfunction in the male population and only 9.1% in the female population. CONCLUSIONS: In this age controlled population study impaired left ventricular systolic function and heart failure increased substantially with age and was more than twice as frequent among men as among women. Asymptomatic left ventricular dysfunction occurred more frequently in men than in women and was less prevalent with increasing age.

Age Factors↗
PubMed2003

The influence of age, sex and other variables on the plasma level of N-terminal pro brain natriuretic peptide in a large sample of the general population.

OBJECTIVE: To identify potentially confounding variables for the interpretation of plasma N-terminal pro brain natriuretic peptide (NT-proBNP). DESIGN: Randomly selected subjects filled in a heart failure questionnaire and underwent pulse and blood pressure measurements, ECG, echocardiography, and blood sampling. SETTING: Subjects were recruited from four Copenhagen general practices located in the same urban area and were examined in a Copenhagen University Hospital. PATIENTS: 382 women and 290 men in four age groups: 50-59 years (n = 174); 60-69 years (n = 204); 70-79 years (n = 174); and > 80 years (n = 120). MAIN OUTCOME MEASURES: Associations between the plasma concentration of NT-proBNP and a range of clinical variables. RESULTS: In the undivided study sample, female sex (p < 0.0001), greater age (p < 0.0001), increasing dyspnoea (p = 0.0001), diabetes mellitus (p = 0.01), valvar heart disease (p = 0.002), low heart rate (p < 0.0001), left ventricular ejection fraction < or = 45% (p < 0.0001), abnormal ECG (p < 0.0001), high log10[plasma creatinine] (p = 0.0009), low log10[plasma glycosylated haemoglobin A1c] (p = 0.0004), and high log10[urine albumin] (p < 0.0001) were independently associated with a high plasma log10[plasma NT-proBNP] by multiple linear regression analysis. CONCLUSIONS: A single reference interval for the normal value of NT-proBNP is unlikely to suffice. There are several confounders for the interpretation of a given NT-proBNP concentration and at the very least adjustment should be made for the independent effects of age and sex.

Age Factors↗
PubMed2000

[Diagnosis of Clostridium difficile infection in pseudomembranous colitis].

C. difficile is known as the main cause of pseudomembranous colitis, however, some individuals may be asymptomatically colonized. In this paper two patients with diarrhoea had three respectively five negative stool cultures. Endoscopically, one patient had severe colitis consistent with both pseudomembranous colitis and inflammatory bowel disease. In the other case the endoscopic findings were typical for pseudomembranous colitis. In both cases there were positive cultures for C. difficile from biopsies from colon-plaques. We find that culture of biopsy of a colon-plaque may contribute to the detection of C. difficile infection in patients with negative stool cultures.

Aged↗
PubMed1999

Exposure scenarios and guidance values for urban soil pollutants.

In general, risk assessments of urban soil pollution are prepared by comparing the levels of pollutants with soil quality criteria. However, large urban areas are contaminated with concentrations of pollutants far exceeding the existing soil quality criteria and would consequently be considered to be of potential risk to humans. This is, however, a rather rigid approach, and for risk management purposes it would be desirable to have more than just one level of soil quality criteria. Therefore, a generic risk assessment model was developed for five different use scenarios: child-care centers, kitchen gardens, ornamental gardens, parks, and sports grounds. In each of the scenarios, three different types of expected behavior are described for children and adults, respectively, resulting in different levels of exposure to the pollutants. For risk management purposes, various guidance values can then be derived for each use scenario. Below a lower guidance value, a free use of the area according to the defined use is possible without an unacceptable risk to the public. Above an upper value, a cutoff of the exposure is necessary. In between, the use may be regulated by different types of advice. The model is still preliminary but was, however, used for derivation of guidance values for five commonly found soil pollutants, of which the results for benzo[a]pyrene and lead are presented.

Adult↗
PubMed1998

Procedure for clinical testing of hearing aids.

In 1996, the Danish audiological clinics and hearing aid manufacturers jointly developed a clinical procedure for testing novel hearing aids in a clinical setting. This endeavour cane about because it was being acknowledged that clinical testing of hearing aids was likely to become more prominent as a result of the more advanced signal processing schemes enabled by digital technology in particular. It was understood that future hearing aids would encompass a large variety of diverse features, and that a rigid and detailed test protocol would therefore be inappropriate. The procedure was therefore devised as a framework within which a test protocol can be developed, and constitutes the framework of good scientific and clinical practice.

Hearing Aids↗
PubMed1998

Improvement in long-term prognosis of elderly patients with acute myocardial infarction after the introduction of intravenous thrombolytic therapy.

Survival rate from a "thrombolytic" period of 351 patients above 66 years of age with acute myocardial infarction (AMI) was compared with that of 289 patients from a "prethrombolytic" period. The two groups were comparable regarding sex, age, previous AMI, cerebrovascular events, morbidity and mortality during admission. Survival rates after four years were 45.0% in the "thrombolytic" group and 38.4% in the "prethrombolytic" group (p = 0.047, log rank test). Using the Cox proportional hazard analysis, thrombolytic therapy was shown to be an independent prognostic predictor in "the thrombolytic population" with a relative risk of death from day 30 to end of follow-up of 0.4 (95% confidence interval 0.2-0.8). No interaction was found between age and thrombolysis. Although only one-fifth of the patients with AMI were eligible for thrombolysis, this treatment may have contributed to the improved long-term survival.

Aged↗
PubMed1997

Cardiac event rates after acute myocardial infarction in patients treated with verapamil and trandolapril versus trandolapril alone. Danish Verapamil Infarction Trial (DAVIT) Study Group.

Angiotensin-converting enzyme (ACE) inhibitors improve survival in patients with congestive heart failure (CHF) after an acute myocardial infarction (AMI), but mortality may be as high as 10% to 15% after 1 year. Verapamil prevents cardiac events after an AMI in patients without CHF. We hypothesized that in postinfarct patients with CHF already prescribed diuretics and an ACE inhibitor, additional treatment with verapamil may reduce cardiac event rate. In this multicenter, double-blind study, patients with CHF receiving diuretic treatment were consecutively randomized to treatment with trandolapril 1 mg/day for 1 month and 2 mg/day the following 2 months (n = 49), or to trandolapril as mentioned plus verapamil 240 mg/day for 1 month and 360 mg/day for 2 months (n = 51). Trial medication started 3 to 10 days after AMI. All patients were followed for 3 months. End points in the trandolapril/trandolapril-verapamil groups were death 1/1, reinfarction 7/1, unstable angina 9/3, and readmission for CHF 6/2. The 3-month first cardiac event rate was 35% in trandolapril-treated patients and 14% in trandolapril-verapamil-treated patients (hazard ratio 0.35, 95% confidence interval 0.15 to 0.85, p = 0.015). These data suggest that verapamil reduces cardiac event rates in post-AMI patients with CHF when added to an ACE inhibitor and a diuretic.

Aged↗
PubMed1997

Treatment with verapamil and trandolapril in patients with congestive heart failure and angina pectoris or myocardial infarction. The DAVIT Study Group. Danish Verapamil Infarction Trial.

In a double-blind, randomized trial in a consecutive group of postinfarct patients in treatment with diuretic agents for congestive heart failure, the 3 month rate of cardiac events (i.e., death, repeat infarction, unstable angina pectoris, or repeat admission because of heart failure) was 14% in patients treated with verapamil and trandolapril and 35% in patients treated with trandolapril (p = 0.01). In another study of patients with angina pectoris and left ventricular ejection fraction less than 40%, trandolapril plus verapamil improved exercise duration and left ventricular ejection fraction. These findings indicate that combined treatment with verapamil and trandolapril may be beneficial in patients with congestive heart failure.

Adult↗
PubMed1997

Treatment with verapamil and trandolapril in patients with congestive heart failure and myocardial infarction. The Danish Verapamil Infarction Trial (DAVIT Study Group).

UNLABELLED: EFFECTS OF VERAPAMIL AND TRANDOLAPRIL: Progression of heart failure, sudden death and death from re-infarction are the major cause of the increased mortality in postinfarct patients with congestive heart failure. Angiotensin converting enzyme (ACE) inhibitors such as trandolapril can prevent the progression of heart failure and thus improve survival. The calcium antagonist verapamil has been shown to prevent sudden death and re-infarction in postinfarct patients without congestive heart failure. HYPOTHESIS: The Danish Verapamil Infarction Trial (DAVIT) study group hypothesized the combined treatment with trandolapril and verapamil might prevent cardiac events in postinfarct patients with coronary heart disease. The first double-blind randomized trial included 100 patients and supported this hypothesis, as the cardiac event rate was significantly lower after 3 months in patients treated with the combination than in those treated with trandolapril alone (14 versus 35%, respectively; P = 0.01, hazard ratio 0.35, 95% confidence interval 0.15-0.85).

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

Time course of platelet alpha granule release in acute myocardial infarction treated with streptokinase.

OBJECTIVE: To determine the time course of platelet alpha granule release in patients with acute myocardial infarction treated with streptokinase. DESIGN: A prospective study. SETTING: Coronary care unit. PATIENTS: Nine with myocardial infarction treated with both streptokinase and aspirin, and nine with acute chest pain but without myocardial infarction, who were treated with aspirin only. METHODS: All patients received 250 mg aspirin on admission and 150 mg once daily thereafter. All patients who fulfilled the indications for streptokinase received 1.5 megaunits, in a single infusion. After the initial medication, serial measurements of plasma beta thromboglobulin and plasma platelet factor 4 were performed at fixed intervals after the onset of chest pain. The primary endpoint sought was the peak value of beta thromboglobulin and platelet factor 4 in each individual. RESULTS: The median peak plasma beta thromboglobulin in the infarction group was substantially higher than in those without infarction, at 37 (range 12 to 210) v 15 (9 to 36) mg/litre, P < 0.01. The corresponding values for plasma platelet factor 4 were 4.6 (2.4 to 60.0) v 2.2 (< 2 to 8.5) mg/litre, P < 0.01. Increased values were seen only within the first 12 h after onset of chest pain, and after 12 h there was no difference between the patients with myocardial infarction and those without. Aspirin treatment did not abolish alpha granule release. CONCLUSIONS: In patients with acute myocardial infarction treated with streptokinase the content of the alpha granules is released within the first 12 h after the onset of chest pain. Aspirin apparently does not abolish this release.

Adult↗
PubMed1994

Principal component analysis of dynamic positron emission tomography images.

Multivariate image analysis can be used to analyse multivariate medical images. The purpose could be to visualize or classify structures in the image. One common multivariate image analysis technique which can be used for visualization purposes is principal component analysis (PCA). The present work concerns visualization of organs and structures with different kinetics in a dynamic sequence utilizing PCA. When applying PCA on positron emission tomography (PET) images, the result is initially not satisfactory. It is illustrated that one major explanation for the behaviour of PCA when applied to PET images is that it is a data-driven technique which cannot separate signals from high noise levels. With a better understanding of the PCA, gained with a strategy of examining the image data set, the transformations, and the results using visualization tools, a surprisingly easily understood methodology can be derived. The proposed methodology can enhance clinically interesting information in a dynamic PET imaging sequence in the first few principal component images and thus should be able to aid in the identification of structures for further analysis.

Artifacts↗
PubMed1994

MUSE--a new tool for interactive image analysis and segmentation based on multivariate statistics.

MUSE--a new software tool for the interactive exploration of multivariate images and the development of image segmentation methods has been designed, implemented, and tested in a number of real application projects. The multivariate statistical classification and projection methods in MUSE can be used not only to analyze multispectral images but also, in special cases, multitemporal images and volume images. Additionally MUSE can be applied to normal greyscale images provided they are made multivariate through an initial processing step. This step may consist in the application of filters designed to enhance any existing texture differences between different regions in the images. MUSE has been successfully applied to medical images (color photographs, MR, PET, SPECT) as well as to satellite images (Landsat TM).

Diagnostic Imaging↗
PubMed1994

Is there a relationship between the acoustic occlusion effect and the sensation of occlusion?

The objective of the present investigation was to examine the relationship between the acoustic occlusion effect and the subjective occlusion sensation when using ear moulds. The material comprises 45 subjects (19M and 26F, at a median age of 76 years, range 38-88 years) subgrouped according to the classification of their hearing disorder into two group: N = 22 subjects with conductive hearing loss (1); N = 21 subjects with sensorineural hearing loss (2). The side effects caused by an ear mould were evaluated at an interview, based on a structured questionnaire, two months after the hearing aid fitting. The comparative investigation showed that when the outer ear canal was occluded with an ear mould there were no significant differences between the two groups of subjects in the frequency of sensation of occlusion, in the sound quality of environmental sound or own voice, in hearing problems when chewing, or in ventilation problems. Neither were significant differences in the magnitude of the acoustic occlusion effect present between those answering yes and those answering yes and those answering no to a change in the sound quality of own voice in the group with sensorineural hearing loss. Although the number of subjects is limited, it is concluded that no relationship exists between the acoustic occlusion effect and the perceived sound quality, thus leaving no physical basis for the claim that this side effect is caused by an ear mould.

Adult↗
PubMed1993

Effects of atenolol and diltiazem on exercise tolerance and ambulatory ischaemia.

Twenty-five normotensive patients with stable angina, angiographically documented coronary disease and normal left ventricular function were randomized to a crossover study comparing atenolol 100 mg x 1, sustained-release diltiazem 120 mg x 2, and their combination. A maximal symptom limited bicycle exercise test and a 24-h ambulatory electrocardiographic (ECG) monitoring were performed at the end of each treatment period. Exercise duration was increased equally in the different treatment groups. Time to onset of 1-mm ST-segment depression was longer with atenolol (P < 0.02) and combination therapy (P < 0.01) than with diltiazem. The maximal ST-segment depression was decreased with atenolol (P < 0.05) and combination therapy (P < 0.02), whereas, time to onset of angina was prolonged only with combination therapy (P < 0.03). The number of ischaemic episodes during ambulatory monitoring was lower with atenolol and combination therapy than with diltiazem (P < 0.01). The difference between atenolol and diltiazem was mainly due to lower ischaemic activity with atenolol between 06:00 h and 12:00 h (P < 0.05). Anginal frequency (P < 0.01) and nitroglycerin consumption (P < 0.05) were lower with combination therapy than with monotherapy. Thus, while comparable effects were achieved on clinical variables, atenolol appeared to be more effective than diltiazem, reducing myocardial ischaemia during exercise and ambulatory monitoring. With combination therapy, both clinical and electrocardiograph signs of ischaemia were improved.

Adult↗