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Sökning: L773:1475 0961 OR L773:1475 097X

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1.
  • Abrahamsson, Pernilla, et al. (författare)
  • Surface microdialysis sampling : a new approach described in a liver ischaemia model
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:2, s. 99-105
  • Tidskriftsartikel (refereegranskat)abstract
    • We recently have shown that samples from microdialysis (MD) probes placed on the surface of the heart reflect metabolic events in the myocardium. This new interesting observation challenges us to consider whether surface application of MD applies to other parenchymatous organs and their surfaces. In 13 anesthetized pigs, transient liver ischaemia was achieved by occlusion of arterial and venous inflow to the liver. Two probes on liver surface and two in parenchyma were perfused with a flow rate of 1 mu l per min (n = 13). An identical set-up was used for probes with a flow rate of 2 mu l per min (n = 9). Samples were collected for every 15-min period during 60 min of baseline, 45 min of ischaemia and 60 min of reperfusion. Lactate, glucose, pyruvate and glycerol were analysed in MD samples. We focused on relative changes in the present study. There was a strong agreement in relative lactate and glucose levels between probes placed on liver surface and those on parenchyma. No significant differences in relative changes in lactate and glucose levels were seen between samples from surface probes and probes in liver parenchyma during equilibration, baseline, ischaemia or reperfusion with a flow rate of 1 mu l per min. MD sampling applied on the liver surface is a new application area for the MD technique and may be used to monitor liver metabolism during both physiological and pathophysiological conditions.
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2.
  • Dahlén, Elsa M, et al. (författare)
  • Is there an underestimation of intima-media thickness based on M-mode ultrasound technique in the abdominal aorta?
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:1, s. 1-4
  • Tidskriftsartikel (refereegranskat)abstract
    • Measuring intima-media thickness (IMT) in the common carotid artery (CCA) is a valuable resource for the evaluation of subclinical atherosclerosis. The main objective of this study was to explore whether a B-mode ultrasound technique, Philips ATL, and an M-mode ultrasound technique, Wall Track System (WTS), show interchangeable results when measured in CCA and the abdominal aorta (AA). A total of 24 healthy, young subjects were examined. IMT and lumen diameter (LD) of the AA and the CCA were measured twice by two skilled ultrasonographers with two different ultrasound equipment B-mode: (Philips, ATL and M-mode: WTS).The intra-observer variability of IMT in CCA and AA using B-mode showed a coefficient of variation 8% and 9%, and with M-mode 11% and 15%, respectively. Interobserver variability of IMT in CCA and AA using B-mode was 6% and 12%, and with M-mode 11% and 18%, respectively. CCA IMT was 0·53 ± 0·07 and 0·53 ± 0·09 mm using B-mode and M-mode, respectively. However, in AA, IMT was 0·61 ± 0·5 and 0·54 ± 0·10 mm using B-mode and M-mode, respectively. Thus, AA IMT was 11·5% thicker using B-mode (P<0·01). We received adequate IMT readings from the carotid artery as well as the AA using two commonly used B-mode and M-mode techniques. B-mode technique seems to show less variability, especially in the AA. More importantly, the two techniques measured different IMT thickness in the aorta, emphasizing the importance of using similar technique when comparing the impact of absolute values of IMT on cardiovascular disease.
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4.
  • Hägerström, Douglas, et al. (författare)
  • A new automated method for analysis of rCBF-SPECT images based on the active-shape algorithm: Normal values
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 32, s. 114-119
  • Tidskriftsartikel (refereegranskat)abstract
    • Most nuclear medicine clinicians use only visual assessment when interpreting regional cerebral blood flow (rCBF) from single-photon emission computed tomography (SPECT) images in clinical practice. The aims of this study were to develop a new, easy to use, automated method for quantification of rCBF-SPECT and to create normal values by using the method on a normal population. We developed a 3-dimensional method based on a brain-shaped model and the active-shape algorithm. The method defines the surface shape of the brain and then projects the maximum counts 0-1·5cm deep for designated surface points. These surface projection values are divided into cortical regions representing the different lobes and presented relative to the whole cortex, cerebellum or cerebellar maximum.99mTc-hexa methyl propylene amine oxime (HMPAO) SPECT was performed on 30 healthy volunteers with a mean age of 74years (range 64-98). The ability of the active-shape algorithm to define the shape of the brain was satisfactory when visually scrutinized. The results of the quantification show rCBF values in the frontal, temporal and parietal lobes of 87-88% using cerebellum as the reference. There were no significant differences in normal rCBF values between male and female subjects and only a weak relation between rCBF and age. In conclusion, our new automated method was able to quantify rCBF-SPECT images and create normal values in ranges as expected. Further studies are needed to assess the clinical value of this method and the normal values. © 2011 The Authors. Clinical Physiology and Functional Imaging © 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine.
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5.
  • Lasaitiene, Daina, 1970, et al. (författare)
  • Neonatal ACE inhibition in rats interferes with lung development
  • 2004
  • Ingår i: Clin Physiol Funct Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 24:1, s. 65-8
  • Tidskriftsartikel (refereegranskat)abstract
    • The renin-angiotensin system (RAS) is developmentally up-regulated and it is essential for kidney development in several species. Given the fact that the rat lung undergoes postnatal development, the mammalian lung possesses the highest angiotensin-converting enzyme (ACE) levels and ACE activity increases during the first weeks postpartum, we tested the hypothesis that ACE inhibition influences postnatal lung development. Rats were given the ACE inhibitor enalapril (10 mg kg(-1)) from 0 to 9 days of age and their lungs were examined at day 4 and 9. Lung structure was evaluated by means of light microscopy, and surface tension of bronchoalveolar lavage fluid was measured by means of a Wilhelmy balance. Neonatal ACE inhibition lowered the surface tension of bronchoalveolar lavage fluid and caused widening of respiratory airspaces and thinning of alveolar septa. Our results suggest that early postnatal ACE inhibition in rats interferes with lung development.
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7.
  • Magnusson, Ylva, 1967, et al. (författare)
  • Lipid imaging of human skeletal muscle using TOF-SIMS with bismuth cluster ion as a primary ion source.
  • 2008
  • Ingår i: Clinical physiology and functional imaging. - 1475-0961 .- 1475-097X. ; 28:3, s. 202-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Intramyocellular lipids are of importance in lipid-related diseases. The techniques in this field are limited because of a lack of adequate tools for localization of various lipids. The most usual methods for the localization of lipid distribution in the skeletal muscle are histochemistry and fluorescence probes. Different chromatography methods and mass spectrometry techniques have also been used for lipid identification. Our aim was to localize the spatial distribution of lipids in their native forms by using static time-of-flight secondary-ion mass spectrometry (TOF-SIMS). Human percutaneous skeletal muscle biopsies were obtained from the middle part of the lateral vastus muscle in the right leg of healthy adolescents with a body mass index >30. Samples were prepared by high-pressure freezing, freeze-fracturing and freeze-drying, and analysed by imaging TOF-SIMS equipped with a Bi3+ cluster ion gun. In the positive spectra, we identified phosphocholine, cholesterol, diacylglycerol, phospholipids and triacylglycerol. Phosphocholine was localized to the edge of the fibre, representing the sarcoplasma or endomysium. Weak cholesterol signals were observed in the intracellular areas. High diacylglycerol and low triacylglycerol signal intensities were seen in intracellular spaces of the transversal area of the muscle fibre. In the negative spectra, we identified fatty acids. We observed co-localization of fatty acids and diacylglycerol, which may indicate lipid-storing parts of the skeletal muscle. Thus, TOF-SIMS imaging can be used to depict the heterogeneous localization of lipids in human skeletal muscle.
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8.
  • Ostenfeld, Ellen, et al. (författare)
  • Comparison of different views with three-dimensional echocardiography : apical views offer superior visualization compared with parasternal and subcostal views
  • 2008
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 28:6, s. 409-416
  • Tidskriftsartikel (refereegranskat)abstract
    • Studies seeking to validate real-time three-dimensional echocardiography (3DE) with regard to cardiac function and dimensions have almost exclusively used apical views. However, it has never been examined whether apical views are preferable to parasternal or subcostal views. In the present study, we compared the feasibility of 3DE volumetric measurements of the four heart chambers in three different views. We included 40 patients planned for a routine two-dimensional transthoracic echocardiography examination (2DE). All patients were scanned with both 2DE and 3DE (Sonos 7500; Philips Medical Systems Andover, MA, USA). Parasternal, apical and subcostal views were used for 3DE. Volumes were calculated using manual tracing in 16 planes. 2DE was performed in parasternal longaxis, subcostal and apical four- and two-chamber views. Manual tracing was used for area calculations. To be judged fully traceable, 5/6 (85%) or more of the ventricular and atrial walls had to be adequately visualized in each plane. The left ventricle and left atrium were adequately visualized in the 3DE apical view in 34 (85%) and 40 (100%) patients, respectively. Visualization of the right atrium was adequate in 31 (78%) patients, whereas the right ventricle was adequately visualized in only 12 (30%) patients. The apical view of 3DE provided superior visualization of all four heart chambers compared with the parasternal and subcostal views, when applying a slight off-axis approach for both ventricles when needed. Thus, in the present study, there was no incremental value of assessment of chamber volumes in the parasternal and subcostal views.
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9.
  • Rosendahl, Lene, 1963-, et al. (författare)
  • Computer-assisted calculation of myocardial infarct size shortens the evaluation time of contrast-enhanced cardiac MRI
  • 2008
  • Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 28:1, s. 1-7
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Delayed enhancement magnetic resonance imaging depicts scar in the left ventricle which can be quantitatively measured. Manual segmentation and scar determination is time consuming. The purpose of this study was to evaluate a software for infarct quantification, to compare with manual scar determination, and to measure the time saved.Methods: Delayed enhancement magnetic resonance imaging was performed in 40 patients where myocardial perfusion single photon emission computed tomography imaging showed irreversible uptake reduction suggesting a myocardial scar. After segmentation, the semi-automatic software was applied. A scar area was displayed, which could be corrected and compared with manual delineation. The different time steps were recorded with both methods.Results: The software shortened the average evaluation time by 12.4min per cardiac exam, compared with manual delineation. There was good correlation of myocardial volume, infarct volume and infarct percentage (%) between the two methods, r = 0.95, r = 0.92 and r = 0.91 respectively.Conclusions: A computer software for myocardial volume and infarct size determination cut the evaluation time by more than 50% compared with manual assessment, with maintained clinical accuracy.
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10.
  • Rydén Ahlgren, Åsa, et al. (författare)
  • Female gender increases stiffness of elastic but not of muscular arteries in type I diabetic patients
  • 2002
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 22:6, s. 409-415
  • Tidskriftsartikel (refereegranskat)abstract
    • The reason for the particularly increased risk for cardiovascular complications in diabetic women is still unclear. We have previously found decreased distensibility of elastic arteries in type I diabetic women, indicating increased cardiac load, not seen in type I diabetic men, which might be one contributing factor. Whether the effect of gender is different in muscular arteries in type I diabetic patients has not been assessed. As estimates of arterial distensibility we measured stiffness (▀) and pressure strain elastic modulus (Ep) in the muscular common femoral artery using echotracking sonography in 30 women (mean age 34 years, range 20-61) and 26 men (mean age 38 years, range 22-56) with type I diabetes. The results were compared with those of 89 healthy individuals of corresponding age and gender and with previously published results from elastic arteries in these patients obtained at the same occasion. The internal common femoral diameter was significantly decreased in both diabetic men and women. In sharp contrast to the highly significant decreased distensibility of the elastic abdominal aorta and common carotid artery in the type I diabetic women, the distensibility of the common femoral artery did not clearly differ between patients and controls, neither for women nor for men. Thus, the gender difference in changes of arterial distensibility found in elastic arteries was absent or far less obvious in the femoral artery. In conclusion, female gender seems to affect the mechanical properties of elastic, but not of large muscular arteries in type I diabetic patients. Thus, putative gender differences in arterial changes in type I diabetes are to be sought in elastic rather than muscular arteries.
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11.
  • Steding Ehrenborg, Katarina, et al. (författare)
  • Respiratory indices by gas analysis and fat metabolism by indirect calorimetry in normal subjects and triathletes.
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30, s. 146-151
  • Tidskriftsartikel (refereegranskat)abstract
    • Summary Background: The effects of exercise on different indices reflecting the metabolism have been of interest for a long time, and a relationship between anaerobic indices and maximal oxygen uptake has been established. The inter-relationship between different respiratory indices during an exercise test remains to be studied in order to understand differences between individuals. Therefore, the aim of this study was to determine three respiratory indices and investigate their inter-relationship in individuals with highly variable working capacity. A second aim was to investigate the fat metabolism at the VO(2) corresponding to the respiratory compensation point (Pq) in the different subjects using indirect calorimetry. Methods: Sixty control subjects (20 female) and 18 triathletes (six female) performed an exercise test with gas analysis. Three respiratory indices, derivative crossing (Dx), point of crossing (Px) and respiratory compensation point (Pq), were calculated using a computerized method. Fat metabolism at Pq was calculated using indirect calorimetry. Results: Two different sequences of the respiratory indices were found: Dx
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12.
  • Sörensen, Jens, et al. (författare)
  • Simultaneous quantification of myocardial perfusion, oxidative metabolism, cardiac efficiency and pump function at rest and during supine bicycle exercise using 1-11C-acetate PET - a pilot study
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:4, s. 279-284
  • Tidskriftsartikel (refereegranskat)abstract
    • Background:  PET using 1-11C-acetate (ACE-PET) applied at rest is used for measuring absolute myocardial blood flow (MBF) and oxidative metabolic rate (kmono). We evaluated the feasibility of quantitative ACE-PET during exercise. Methods:  Five endurance athletes underwent dynamic PET scanning at rest and during supine bicycle stress. Exercise was maintained at a workload of 120 Watt for 17 min. The rate-pressure product (RPP) was recorded repeatedly. MBF, kmono in left (LV) and right (RV) ventricular wall, cardiac output (CO), cardiac efficiency and a lung uptake value reflecting left heart diastolic pressures were calculated from the PET data using previously validated models. Results:  MBF increased from 0·71 ± 0·17 to 2·48 ± 0·25 ml min−1 per ml, LV-kmono from 0·050 ± 0·005 to 0·146 ± 0·021 min−1, RV-kmono from 0·023 + 0·006 to 0·087 + 0·014 min-1, RPP from 4·7 ± 0·8 to 13·2 ± 1·4 mmHg × min−1 × 103 and Cardiac Output from 5·2 ± 1·1 to 12·3 ± 1·2 l min −1 (all P < 0·001). Cardiac efficiency was unchanged (P = 0·99). Lung uptake decreased from 1·1 ± 0·2 to 0·6 ± 0·1 ml g−1 (P < 0·001). Discussion:  A number of important parameters related to cardiac function can be quantified non-invasively and simultaneously with a short scanning protocol during steady state supine bicycling. This might open up new opportunities for studies of the integrated cardiac physiology in health and early asymptomatic disease.
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13.
  • Wisén, Anita, et al. (författare)
  • A refined technique for determining the respiratory gas exchange responses to anaerobic metabolism during progressive exercise - repeatability in a group of healthy men.
  • 2004
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 24:1, s. 1-9
  • Tidskriftsartikel (refereegranskat)abstract
    • The respiratory gas exchange and ventilation during an incremental cycle exercise test were analysed in a group of 19 healthy, moderately fit men. Different computer algorithms were used to estimate the VO2 values where: (i) the rate of VCO2 increase just exceeds the rate of VO2 increase (DX, derivative crossing), (ii) VCO2/VO2 = 1·00 (PX, point of crossing) and (iii) ventilation (VE) increases disproportionately in relation to VCO2 (PQ, point of VCO2 equivalent rise). The DX and PQ measurements were analysed using a new approach employing polynomial regression and the value of PX was determined following low-pass filtration of raw data. The repeatability of the measurements was evaluated with a 5-6 week interval between the tests. The correlations between tests were 0·75 at DX, 0·85 at PX and 0·62 at PQ. The mean differences between the repeated tests were not statistically significant. The repeatability of VO2, in absolute values expressed as ±2 SD of the differences between the tests, had values of 5·0, 6·1 and 9·5 ml min-1 kg-1 for DX, PX and PQ, respectively. The mean value of VO2 for each measurement point expressed as a percentage of VO2max was 54% at DX, 68% at PX and 70% at PQ. The most common sequence of the measured values was DX < PX < PQ, but the sequence DX < PQ < PX was also observed. It is concluded that the gas exchange responses to developing anaerobic metabolism during progressive exercise can be characterized by a series of thresholds. However, the considerable variation in absolute values in the two testing occasions requires further attention.
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14.
  • Aneq Åström, Meriam, et al. (författare)
  • Determination of right ventricular volume and function using multiple axially rotated MRI slices
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - : Blackwell Publishing Ltd. - 1475-0961 .- 1475-097X. ; 31:3, s. 233-239
  • Tidskriftsartikel (refereegranskat)abstract
    • Pandgt;Background: The conventional magnetic resonance imaging (MRI) method for right ventricular (RV) volume and motion, using short-axis (SA) orientation, is limited by RV anatomy and shape. We suggest an orientation based on six slices rotated around the long axis of the RV, rotated long axis (RLA). Materials and methods: Three phantoms were investigated in SA and RLA using cine balanced steady-state free precession MRI. Volumes were calculated based on segmentation and checked against true volumes. In 23 healthy male volunteers, we used six long-axis planes from the middle of the tricuspid valve to the RV apex, rotated in 30 degrees increments. For comparison, short-axis slices were acquired. Imaging parameters were identical in both acquisitions. Results: Right ventricular end-diastolic (EDV), end-systolic (ESV) and stroke volumes (SV) determined in the RLA 179 center dot 1 +/- 29 center dot 3; 80 center dot 1 +/- 17 center dot 1; 99 center dot 3 +/- 16 center dot 9 ml and in the SA were 174 center dot 0 +/- 21 center dot 1; 78 center dot 8 +/- 13 center dot 6; 95 center dot 3 +/- 14 center dot 5 ml with P-values for the difference from 0 center dot 17 to 0 center dot 64 (ns). Interobserver variability ranged between 3 center dot 2% and 6 center dot 6% and intraobserver variability between 2 center dot 8% and 6 center dot 8%. In SA views, consensus for the definition of the basal slice was necessary in 39% of the volunteers for whom the average volume change was 20% in ESV and 10% in EDV. Conclusions: The RLA method results in better visualization and definition of the RV inflow, outflow and apex. Accurate measurement of RV volumes for diagnosis and follow-up of cardiac diseases are enhanced by the RLA orientation, even though additional acquisition time is required.
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15.
  • Abrahamsson, Pernilla, et al. (författare)
  • Detection of myocardial ischaemia using surface microdialysis on the beating heart
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 31:3, s. 175-181
  • Tidskriftsartikel (refereegranskat)abstract
    • Microdialysis (MD) can be used to study metabolism of the beating heart. We investigated whether microdialysis results obtained from epicardial (surface) sampling reflect acute changes in the same way as myocardial sampling from within the substance of the ventricular wall. In anaesthetized open-thorax pigs a coronary snare was placed. One microdialysis probe was placed with the sampling membrane intramyocardially (myocardial), and a second probe was placed with the sampling membrane epicardially (surface), both in the area which was made ischaemic. Ten minutes collection intervals were used for microdialysis samples. Samples from 19 pigs were analysed for lactate, glucose, pyruvate and glycerol during equilibration, baseline, ischaemia and reperfusion periods. For both probes (surface and myocardial), a total of 475 paired simultaneous samples were analysed. Results from analyses showed no differences in relative changes for glucose, lactate and glycerol during baseline, ischaemia and reperfusion. Surface microdialysis sampling is a new application of the microdialysis technique that shows promise and should be further studied.
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16.
  • Ahlund, Catherine, et al. (författare)
  • Pulse wave analysis on fingertip arterial pressure : effects of age, gender and stressors on reflected waves and their relation to brachial and femoral artery blood flow
  • 2008
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 28:2, s. 86-95
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: Analysis of the contour of the arterial pressure pulse (pulse wave analysis; PWA) adds information about arterial stiffness etc., beyond that obtained from absolute pressures. Peripheral pulses normally show an anterograde systolic peak and two reflected peaks: one in systole and one in diastole. The amplitudes and timings of these were estimated from finger pressure recordings in three study groups. We studied the usefulness of continuous digital pressures for PWA. METHODS: First, PWA from intra-arterial (brachial) and non-invasive finger pressure recordings was compared. Secondly, stress-induced (mental arithmetics and cold pressor test) changes in pressure pulse reflection were compared with blood flow changes in brachial and femoral arteries (ultrasound). Thirdly, the influence of age and gender on digital pulse pressures was investigated at rest and during exercise. RESULTS AND CONCLUSION: Pulse wave analysis results from brachial and digital pressures correlated strongly. Stress induced changes in systolic reflection were associated with changes in brachial artery flow patterns, whereas diastolic reflection was associated with femoral artery flow changes. At rest, age increased systolic reflection without affecting diastolic reflection. Exercise increased systolic reflection and reduced diastolic reflection more in older subjects (>40 years) than in younger (<40 years). In conclusion, PWA from continuous, digital pressure recordings is a convenient technique to study the arterial function at rest and during exposure to stressors in broad populations. The two reflected waves are differently regulated, which may indicate different anatomical origin.
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17.
  • Appelberg, Jonas, 1964-, et al. (författare)
  • Lung aeration during sleep in patients with obstructive sleep apnoea
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - Oxford : Blackwell Publishing. - 1475-0961 .- 1475-097X. ; 30:4, s. 301-307
  • Tidskriftsartikel (refereegranskat)abstract
    • P>Background: Previous studies have indicated that patients with obstructive sleep apnoea (OSA) have altered ventilation and lung volumes awake and the results suggest that this may be a determinant of severity of desaturations during sleep. However, little is known about regional lung aeration during sleep in patients with OSA. Methods: Twelve patients with OSA were included in the study. Computed tomography was used to study regional lung aeration during wakefulness and sleep. Lung aeration was calculated in ml gas/g lung tissue in four different regions of interest (ROI1-4), along the border of the lung from ventral to dorsal. Results: Lung aeration in the dorsal (dependent) lung region (ROI4) was lower during sleep compared to wakefulness 0 center dot 78 +/- 0 center dot 19 versus 0 center dot 88 +/- 0 center dot 19 (mean +/- SD) ml gas/g lung tissue (P = 0 center dot 005). Associations were found between awake expiratory reserve volume and change in lung aeration from wakefulness to sleep in ROI4 (r = -0 center dot 69; P = 0 center dot 012). In addition, the change in lung aeration in the dorsal region correlated to sleep time (r = 0 center dot 69; P = 0 center dot 014) but not to time in supine position. The difference in lung aeration between inspiration and expiration (i.e. ventilation), was larger in the ventral lung region when expressed as ml gas per g lung tissue. In two patients it was noted that, during on-going obstructive apnoea, lung aeration tended to be increased rather than decreased. Conclusions: Aeration in the dorsal lung region is reduced during sleep in patients with OSA. The decrease is related to lung volume awake and to sleep time.
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18.
  • Bjällmark, Anna, et al. (författare)
  • Differences in myocardial velocities during supine and upright exercise stress echocardiography in healthy adults
  • 2009
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 29:3, s. 216-223
  • Tidskriftsartikel (refereegranskat)abstract
    • Tissue Velocity Imaging (TVI) is a method for quantitative analysis of longitudinal myocardial velocities, which can be used during exercise and pharmacological stress echocardiography. It is of interest to evaluate cardiac response to different types of stress tests and the differences between upright and supine bicycle exercise tests have not been fully investigated. Therefore, the aim of this study was to compare cardiac response during supine and upright exercise stress tests. Twenty young healthy individuals underwent supine and upright stress test. The initial workload was set to 30 W and was increased every minute by a further 30 W until physical exhaustion. Tissue Doppler data from the left ventricle were acquired at the end of every workload level using a GE Vivid7 Dimension system (> 200 frames s(-1)). In the off-line processing, isovolumic contraction velocity (IVCV), peak systolic velocity (PSV), isovolumic relaxation velocity (IVRV), peak early diastolic velocity (E') and peak late diastolic velocity (A') were identified at every workload level. No significant difference between the tests was found in PSV. On the contrary, E' was shown to be significantly higher (P < 0.001) during supine exercise than during upright exercise and IVRV was significantly lower (P < 0.001) during supine exercise compared to upright exercise. Upright and supine exercise stress echocardiography give a comparable increase in measured systolic velocities and significant differences in early diastolic velocities.
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19.
  • Björkander, Inge, et al. (författare)
  • Long-term stability of heart rate variability in chronic stable angina pectoris, and the impact of an acute myocardial infarction
  • 2009
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30, s. 698-699
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Heart rate variability (HRV) reflects the balance between cardiac parasympathetic and sympathetic autonomic influences. Reduced HRV has adverse prognostic implications. The time course for changes in HRV over prolonged periods of time and the influence of an acute coronary event on HRV are not well established. METHODS: Heart rate variability was assessed in patients with chronic stable angina pectoris, who were followed for 3 years within the Angina Prognosis Study in Stockholm. Patients who suffered an acute myocardial infarction after the study were re-examined after this event. We assessed HRV by the simple geometric method differential index, and traditional time- and frequency-domain measurements of HRV. RESULTS: The differential index was essentially unchanged during the study (i.e. the ratio month 36/month 1 was 1.00 +/- 0.06, n = 261). Also most other time and frequency indices of HRV (SDNN, r-MSSD, SDNNIDX, total power, and VLF, LF, HF respectively; n = 63) remained largely unchanged; pNN50 and LF/HF were, however, less reproducible. In 21 patients with a subsequent acute myocardial infarction, SDNN, SDNNIDX, total power, LF and LF/HF were reduced following the event, whereas differential index, pNN50 and HF remained unchanged. CONCLUSIONS: Differential index and other indices of HRV are stable and reproducible in patients with chronic stable angina pectoris. High-frequency HRV (reflecting cardiac parasympathetic activity) and the differential index changed little following an acute coronary event, and may be suitable for predictions of the future risk of sudden death even in the presence of a recent acute coronary event.
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20.
  • Blomstrand, Peter, et al. (författare)
  • Pulsed tissue Doppler imaging for the detection of myocardial ischaemia, a comparison with myocardial perfusion SPECT
  • 2004
  • Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 24:5, s. 289-295
  • Tidskriftsartikel (refereegranskat)abstract
    • In order to compare the diagnostic ability of pulsed tissue Doppler and myocardial perfusion Single Photon Emission Computed Tomography (SPECT) in patients with a history of unstable coronary artery disease, CAD, 26 patients, 22 men and four women, age 47-76 years, were investigated in a prospective study, 5-10 day after an episode of unstable angina. Tissue Doppler and two-dimensional echocardiography were performed during dobutamine stress testing and myocardial scintigraphy after bicycle exercise and at rest. Patients with a normal SPECT had higher peak systolic velocity during dobutamine infusion, 18.9 ± 4.1 cm s-1, than patients with ischaemia, 12.2 ± 3.8 cm s-1 (P<0.001) or scar, 8.8 ± 3.0 cm s-1 (P<0.01). In a territorial analysis the difference in peak systolic velocity between areas with a normal and abnormal SPECT was less apparent. Failure to achieve ≥13 cm s-1 in mean-peak systolic velocity was the most accurate criterion for detection of significant CAD on SPECT. We conclude that pulsed tissue Doppler can be used for objective quantification of left ventricular wall motion during dobutamine stress testing and for identification of patients with CAD on SPECT but not for identification of regional ischaemia.
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21.
  • Brodin, Lars-Åke (författare)
  • Tissue Doppler, a fundamental tool for parametric imaging
  • 2004
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 24:3, s. 147-155
  • Tidskriftsartikel (refereegranskat)abstract
    • Tissue Doppler has been used for clinical applications since 1989. It has been developed from a pulsed Doppler acquisition tool towards a method where extraction of velocities can be performed from colour-coded images. This has introduced a further development into different forms of parametric images describing different myocardial functions as colour-coded information, like deformation imaging, motion imaging and phase imaging. The technical requirements have been established with temporal requirements of frame rates in acquisition exceeding 100 frames s(-1). The most powerful application of the tissue Doppler technique today is perhaps to quantify the myocardial functional reserve, during stress echocardiography, making the method applicable to diagnose the presence of coronary disease with an accuracy exceeding that of nuclear and other non-invasive techniques. The method has also great potential for future developments with introduction of more regional measuring variables.
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22.
  • Carlhäll, Carljohan, 1973-, et al. (författare)
  • A novel method to assess systolic ventricular function using atrioventricular plane displacement : a study in young healthy males and patients with heart disease
  • 2004
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 24:4, s. 190-195
  • Tidskriftsartikel (refereegranskat)abstract
    • Analysis of atrioventricular plane displacement (AVPD) is a well established method for assessment of both systolic and diastolic ventricular function. For several years, AVPD has been a clinical tool and there are many current, as well as potential, areas of application. However, clinical work has shown that the traditional method for evaluation of systolic ventricular function, called total AVPD, does not temporally reflect true systole. Systolic AVPD is a new approach for measuring AVPD to assess ventricular systolic function. We wished to apply this new model in healthy subjects and in patients with different common heart diseases. Twenty-eight young healthy males and 30 patients (aortic stenosis, left sided regurgitant lesions, postmyocardial infarction) were enrolled. AVPD was obtained at the four standard sites by M-mode. Total AVPD was measured in the conventional way and systolic AVPD by identifying true systole, by means of mitral- and aortic valve closure respectively. Ventricular volumes were calculated according to biplane Simpson's rule. The systolic AVPD measurements were significantly lower than the total measurements, at both atrioventricular planes in all groups (P<0·001). This discrepancy was greater at the mitral than at the tricuspid annulus in the patients 24·2% vs. 15·5% (P<0·001), but did not differ in the healthy subjects. At the mitral annulus, this discrepancy also seemed to be more pronounced in the patients than in the healthy subjects 24·2% vs. 10·7%. When assessing ventricular systolic function by AVPD, the conventional method overestimates the amplitude in relation to true systolic function in both patients with heart disease and in young healthy males. Thus, there are uncertainties regarding earlier estimations of AVPD in terms of expression of systolic function and regarding previously presented reference values. We recommend the proposed methodology.
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23.
  • Claesson, Jonas, et al. (författare)
  • Intestinal circulation, oxygenation and metabolism is not affected by oleic acid lung injury.
  • 2005
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 25:6, s. 357-363
  • Tidskriftsartikel (refereegranskat)abstract
    • This study was performed to establish a platform for further studies on effects of ventilatory treatment modalities on the intestines during mechanical ventilation of acute lung injury (ALI). We tested the hypotheses that oleic acid (OA) infusion causes changes in intestinal circulation, oxygenation and metabolism, and that OA is distributed to tissues outside the lung. This was performed as an experimental, prospective and controlled study in an university animal research laboratory. Thirteen juvenile anaesthetized pigs were used in the main study, where seven were given an intravenous infusion of 0.1 ml kg(-1) OA and six served as control (surgery only). In a separate study, four animals were given an intravenous infusion of 0.1 ml kg(-1) (3)H-labelled OA. We measured systemic and mesenteric (portal venous blood flow, jejunal mucosal perfusion) haemodynamic parameters, mesenteric oxygenation (jejunal tissue oxygen tension) and systemic cytokines (tumour necrosis factor-alpha and interleukin-6). We calculated mesenteric lactate flux and mesenteric oxygen delivery, uptake and extraction ratio. In the animals given 3H-OA, we measured 3H-OA in different tissues (lungs, heart, liver, kidney, stomach, jejunum, colon and arterial blood). We found that OA given intravenously is distributed in small amounts to the intestines. This intestinal exposure to OA does not cause intestinal injury when evaluating mesenteric blood flow, metabolism or oxygenation. OA infusion induced a moderate increase in mean pulmonary arterial pressure and a decrease in PaO2/Fraction inspired O2 (P/F) ratio, giving evidence of severe lung injury. Consequently, the OA lung injury model is suitable for studies on intestinal effects of ventilatory treatment modalities during mechanical ventilation of ALI.
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24.
  • Eiken, Ola, et al. (författare)
  • Effects of local arteriosclerosis on carotid baroreflex sensitivity and on heart rate and arterial pressure variability in humans
  • 2006
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 26:1, s. 9-14
  • Tidskriftsartikel (refereegranskat)abstract
    • The study examined whether the alterations in heart rate variability (HRV) and baroreflex sensitivity (BRS) observed in patients with coronary artery disease can also be discerned in otherwise healthy subjects with mild-to-moderate arteriosclerosis in the carotid artery bifurcation. Based on the results of carotid duplex ultrasonography, subjects were designated as either having no arteriosclerotic lesions (n = 18), unilateral (n = 19) or bilateral lesions (n = 18) in the bifurcation. Electrocardiograms were recorded and simultaneous and continuous records of arterial pressure were obtained. Resting HRV was determined by calculating the spectral power density in three frequency bands: 0-0.05 Hz [very low frequency (VLF) band], 0.05-0.15 [low frequency (LF) band] and 0.15-2 Hz (high frequency band), whereas the arterial pressure variability (APV) was determined from spectral power density of the VLF and LF bands. Carotid BRS was evaluated by measuring R-R intervals during application of pulse-synchronous graded pressures (40 to -65 mmHg) in a neck-chamber device. Analysis of variance revealed no effect of mild-to-moderate carotid arteriosclerosis on the spectral components of HRV and APV or on BRS. It thus appears that mild-to-moderate asymptomatic carotid arteriosclerosis does not affect carotid BRS, APV or HRV at rest.
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25.
  • Ekelund, Ulf, et al. (författare)
  • The validity of the Computer Science and Applications activity monitor for use in coronary artery disease patients during level walking
  • 2002
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 22:4, s. 248-253
  • Tidskriftsartikel (refereegranskat)abstract
    • The principal aim of the present study was to examine the validity of the Computer Science and Applications (CSA) activity monitor during level walking in coronary artery disease (CAD) patients. As a secondary aim, we evaluated the usefulness of two previously published energy expenditure (EE) prediction equations. Thirty-four subjects (29 men and five women), all with diagnosed CAD, volunteered to participate. Oxygen uptake (VO2) was measured by indirect calorimetry during walking on a motorized treadmill at three different speeds (3·2, 4·8 and 6·4 km h−1). Physical activity was measured simultaneously using the CSA activity monitor, secured directly to the skin on the lower back (i.e. lumbar vertebrae 4–5) with an elastic belt. The mean (±SD) activity counts were 1208 ± 429, 3258 ± 753 and 5351 ± 876 counts min−1, at the three speeds, respectively (P<0·001). Activity counts were significantly correlated to speed (r=0·92; P<0·001), VO2 (ml kg−1 min−1; r=0·87; P<0·001) and EE (kcal min−1; r=0·85, P<0·001). A stepwise linear regression analysis showed that activity counts and body weight together explained 75% of the variation in EE. Predicted EE from previously published equations differed significantly when used in this group of CAD patients. In conclusion, the CSA activity monitor is a valid instrument for assessing the intensity of physical activity during treadmill walking in CAD patients. Energy expenditure can be predicted from body weight and activity counts.
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26.
  • Emilsson, Kent, 1963-, et al. (författare)
  • Comparison between aortic annulus motion and mitral annulus motion obtained using echocardiography
  • 2006
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 26:5, s. 257-262
  • Tidskriftsartikel (refereegranskat)abstract
    • Earlier studies have shown that the aortic root, in analogy with the mitral annulus, moves towards the left ventricular apex during systole. However, there are no earlier studies comparing the amplitude of the aortic annulus motion (AAM) with that of the mitral annulus (MAM), which was the main aim of the study. Another aim was to study the intra- and interobserver reproducibility (IIOR) of measuring AAM with M-mode and 2-D echocardiography as it is not obvious which of the methods that should be used. Twenty-one healthy subjects were examined by echocardiography. AAM and MAM were measured at different sites. IIOR was measured in 10 of the subjects. There was no significant difference between average AAM (15.3 +/- 1.5 mm) and average MAM (15.6 +/- 1.5 mm) and there was a rather good agreement between the variables. There was also no significant difference between AAM at the septal site (16.3 +/- 2 mm) and average MAM, but a significant difference between AAM at the lateral site (14.2 +/- 1.6 mm) and average MAM (P<0.001) and between the both sites of measuring AAM (P<0.001). The significant difference between the two sites of measuring AAM may have anatomical reasons but may also depend on difficulties in measuring AAM at the septal site where it has lower reproducibility than at the lateral site. IIOR of measuring AAM was good when using M-mode but poor when using 2-D echocardiography and AAM should preferably be measured using M-mode and not using 2-D echocardiography.
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27.
  • Emilsson, Kent, 1963-, et al. (författare)
  • Comparison between aortic, mitral and tricuspid annular velocities measured with quantitative two-dimensional color Doppler tissue imaging in healthy subjects.
  • 2007
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 27:5, s. 275-83
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: To compare the systolic, early and late diastolic velocities of the aortic, mitral and tricuspid annuli in healthy subjects and to study the intraobserver and interobserver reproducibility (IIOR) of measuring the velocities at the aortic annulus.METHODS: Twenty healthy subjects with mean age 28 years were investigated with quantitative two-dimensional color Doppler tissue imaging and the systolic, early and late diastolic velocities were measured at the aortic, mitral and tricuspid annuli.RESULTS: The mitral annulus had significant higher systolic velocity and early diastolic velocity than the aortic annulus. The late diastolic velocity was significant lower at the aortic annulus compared with the both other annuli. At the different sites of the annuli the highest systolic velocity and early diastolic velocity were measured at the lateral site of the mitral annulus, whereas the lowest systolic velocity was measured at the septal site of the same annulus. The lowest early diastolic velocity was found at the septal site of the aortic annulus. The highest late diastolic velocity was measured at the lateral site of the tricuspid annulus and the lowest at the lateral site of the aortic annulus.CONCLUSIONS: The mitral annulus has statistical significant higher systolic and early diastolic velocities than the aortic annulus. There are significant differences in velocities between several of the different sites of the annuli. IIOR of measuring the systolic and early diastolic velocities of the aortic annulus is good.
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28.
  • Emilsson, Kent, 1963-, et al. (författare)
  • Comparison between maximal early diastolic velocity in long-axis direction obtained by M-mode echocardiography and by tissue Doppler in the assessment of right ventricular diastolic function
  • 2005
  • Ingår i: Clinical Physiology and Functional Imaging. - Oxford : Blackwell. - 1475-0961 .- 1475-097X. ; 25:3, s. 178-182
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently the maximal early diastolic velocity in long-axis direction of the right ventricle (RV) obtained by tissue Doppler imaging (MDV TDI) has been introduced in the assessment of RV diastolic function (RVDF). There are reasons to think that also the maximal early diastolic velocity in long-axis direction of the RV obtained using M-mode echocardiography (MDV TAM) could be used to assess RVDF. Therefore, 29 patients were examined with echocardiography and MDV TAM and MDV TDI were measured and compared. A good correlation (r = 0.76, P< 0.001) was found between MDV TAM and MDV TDI indicating that MDV TAM might be used in the assessment of RVDF. However, the velocities obtained by MDV TDI (126.7 &PLUSMN; 38.9 mm s(-1)) were significantly (P< 0.001) higher than the velocities obtained by MDV TAM (78.3 &PLUSMN; 27.8 mm s(-1)) and the agreement between MDV TAM and MDV TDI was rather poor probably mainly due to differences in the measuring technique. This means that reference values cannot be used interchangeably between MDV TAM and MDV TDI. If MDV TAM is going to be used in the assessment of RVDF new reference values have to be produced if today's technique and recommendations to measure MDV TAM and MDV TDI are used. However, as most new echocardiographs are equipped with PW-TDI technology it seems preferable to use this technique and compare obtained values with already established reference values.
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29.
  • Emilsson, Kent, 1963- (författare)
  • Right ventricular long-axis function in relation to left ventricular systolic function
  • 2004
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 24:4, s. 212-215
  • Tidskriftsartikel (refereegranskat)abstract
    • A decrease in left ventricular (LV) systolic function is accompanied by a decrease in maximal relaxation velocity in LV long-axis direction, but is it also accompanied by a decrease in right ventricular (RV) long-axis function? To study this 35 consecutive patients were examined by echocardiography. Ejection fraction (LVEF) and mitral annulus motion (MAM) were used as indices of LV systolic function and tricuspid annulus motion (TAM), that is the systolic shortening in RV long-axis direction, was used as an index of RV systolic long-axis function. In the same way the maximal relaxation velocity in LV long-axis direction, that is the maximal diastolic velocity of MAM (MDV MAM), has been suggested as an index of LV diastolic function the maximal diastolic velocity of TAM (MDV TAM) can be supposed to be an index of RV diastolic function measuring the maximal relaxation velocity in the RV long-axis direction. A significant positive correlation was found between MDV TAM and MAM (r = 0.64, P<0001) and LVEF (r = 0.54, P = 0.001) and between TAM and the two studied indices of LV systolic function, with the highest correlation to MAM (r = 0.68, P<0.001) and the lowest to LVEF (r = 0.57, P<0.001). Thus, a decrease in LV systolic function is accompanied by a decrease in both systolic and diastolic RV long-axis function, findings that probably are due to the close anatomical connection between the ventricles and to changes that occur in afterload of the RV secondary to LV systolic dysfunction.
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30.
  • Eriksson, Michael, et al. (författare)
  • Impact of physical activity and body composition on heart function and morphology in middle-aged, abdominally obese women.
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:5, s. 354-9
  • Tidskriftsartikel (refereegranskat)abstract
    • Several studies have shown training induced morphological changes in the heart. Our aim was to assess how frequent, low-intensity exercise (walking and cycling) influences heart function and morphology in abdominally obese women. Fifty women with abdominal obesity (mean age 47.0 +/- 7.5 years, waist circumference (WC) 103.2 +/- 7.8 cm), free of cardiovascular problems were recruited. They were equipped with a bicycle and pedometers and instructed to start commuting in a physically active way for 6 months. Evaluation of cardiac function and morphology was performed using echocardiography (ECHO) before and after 6 months of training. The subjects increased significantly their daily physical activity. After 6 months, there was a significant decrease in WC (from 103.3 +/- 7.9 to 100.8 +/- 8.4 cm, P = 0.0003), in systolic and diastolic blood pressure (126.8 +/- 15.2 to 120.4 +/- 14.5 mmHg, P = 0.0001, and 79.8 +/- 7.8 to 77.8 +/- 8.4 mmHg, P = 0.0006, respectively). ECHO showed an increase in the right ventricular (RV) systolic longitudinal function expressed as tricuspid annular motion from 22.00 +/- 3.30 to 23.05 +/- 3.59 mm, P = 0.015; and a similar trend in left ventricular (LV) mitral annular motion, which increased from 13.09 +/- 1.53 to 13.39 +/- 1.47 mm, P = 0.070. Cycling was associated with reductions in LV systolic and RV diastolic dimensions, whereas walking was not associated with any changes in the ECHO-variables. A reduction in WC by frequent, low-intensity exercise in abdominally obese women is associated with decrease in blood pressure and improved longitudinal RV systolic function.
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31.
  • Farnebo, Simon, et al. (författare)
  • Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:1, s. 57-63
  • Tidskriftsartikel (refereegranskat)abstract
    • Pgreater thanIncreasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). MD probes were inserted into the gracilis muscle of 15 rats and perfused with a medium containing urea (20 mmol l-1). Changes in muscle blood flow were made by addition of noradrenaline (5 mu g ml-1) to the perfusion medium at two perfusion velocities (0 center dot 6 and 0 center dot 4 mu l min-1). The clearance of urea from the perfusion medium was then calculated and examined in relation to the dose of noradrenaline and to the coexisting changes in extracellular metabolites. The results showed reproducible and dose-dependent changes in blood flow that were induced by noradrenaline. These were characterized by dose-dependent changes in the urea clearance as well as blood-flow-specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0 center dot 4 compared with the 0 center dot 6 mu l min-1 perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (greater than 90%).
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32.
  • Govind, Satish C., et al. (författare)
  • Acute administration of a single dose of valsartan improves left ventricular functions : a pilot study to assess the role of tissue velocity echocardiography in patients with systemic arterial hypertension in the TVE-valsartan study I
  • 2006
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 26:6, s. 351-356
  • Tidskriftsartikel (refereegranskat)abstract
    • Background The advent of colour-coded tissue velocity echocardiography (TVE) has now made it possible to quantify left ventricular (LV) functions in patients with systemic arterial hypertension (HTN). Hypothesis In this project, we have studied the cardiac effects of a single dose of orally administered valsartan in patients with known HTN. Methods Fifty-five patients with HTN with a mean age of 56 +/- 10 years were given an early morning dose of 80 mg valsartan withholding regular antihypertensive medications on the day of investigation. TVE images, acquired on VIVID systems were digitized for postprocessing of longitudinal and radial peak systolic velocities, strain rate, and systolic and diastolic time intervals before (pre) and 5 h after (post) administration of the drug. Results Blood pressure (mmHg) pre and post, respectively, were 147 +/- 15 versus 137 +/- 14 systolic and 90 +/- 7 versus 86 +/- 7 diastolic (all P < 0.01). LV longitudinal systolic velocities (cm s(-1)) were significantly higher post in LV septum (5.7 +/- 1.1 versus 6.4 +/- 1.6; P < 0.001) with similar results obtained in other LV walls. Radial strain rate (1 s(-1)) was significantly higher post compared with pre valsartan (2.1 +/- 0.6 versus 2.3 +/- 0.9; P < 0.01). Regional diastolic filling and ejection times (ms) were significantly shorter post (390 +/- 122 versus 370 +/- 120 and 275 +/- 32 versus 163 +/- 36 respectively; all P < 0.05). Conclusions Within 5 h after oral administration of valsartan, improvement in regional myocardial systolic functions could be registered. Although the changes could well be secondary to afterload reduction, additional effects of the drug, evidenced by improved strain rate that is relatively load-independent, may have contributed in this improvement.
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33.
  • Gudmundsson, Petri, et al. (författare)
  • Parametric quantification of myocardial ischaemia using real-time perfusion adenosine stress echocardiography images, with SPECT as reference method
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 30:1, s. 30-42
  • Tidskriftsartikel (refereegranskat)abstract
    • SUMMARY BACKGROUND: Real-time perfusion (RTP) adenosine stress echocardiography (ASE) can be used to visually evaluate myocardial ischaemia. The RTP power modulation technique, provides images for off-line parametric perfusion quantification using Qontrast software. From replenishment curves, this generates parametric images of peak signal intensity (A), myocardial blood flow velocity (beta) and myocardial blood flow (Axbeta) at rest and stress. This may be a tool for objective myocardial ischaemia evaluation. We assessed myocardial ischaemia by RTP-ASE Qontrast((R))-generated images, using 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) as reference. METHODS: Sixty-seven patients admitted to SPECT underwent RTP-ASE (SONOS 5500) during Sonovue infusion, before and throughout adenosine stress, also used for SPECT. Quantitative off-line analyses of myocardial perfusion by RTP-ASE Qontrast-generated A, beta and Axbeta images, at different time points during rest and stress, were blindly compared to SPECT. RESULTS: We analysed 201 coronary territories [corresponding to the left anterior descendent (LAD), left circumflex (LCx) and right coronary (RCA) arteries] from 67 patients. SPECT showed ischaemia in 18 patients. Receiver operator characteristics and kappa values showed that A, beta and Axbeta image interpretation significantly identified ischaemia in all territories (area under the curve 0.66-0.80, P = 0.001-0.05). Combined A, beta and Axbeta image interpretation gave the best results and the closest agreement was seen in the LAD territory: 89% accuracy; kappa 0.63; P<0.001. CONCLUSION: Myocardial isachemia can be evaluated in the LAD territory using RTP-ASE Qontrast-generated images, especially by combined A, beta and Axbeta image interpretation. However, the technique needs improvements regarding the LCx and RCA territories.
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34.
  • Gustafsson, T., et al. (författare)
  • Elevations of local intravascular pressures release vasoactive substances in humans
  • 2013
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 33:1, s. 38-44
  • Tidskriftsartikel (refereegranskat)abstract
    • The wall stiffness of arteries and arterioles adapts to the long-term demands imposed by local intravascular pressure. We investigated whether substances capable of inducing acute and long-term effects on arterial wall stiffness are released locally into the bloodstream in response to an acute marked increase in local intravascular pressure in the blood vessels of the human arm. Experiments were performed on ten subjects positioned in a pressure chamber with one arm extended through a hole in the chamber door and kept at normal atmospheric pressure. Intravascular pressure was increased in the arm, by a stepwise increase in chamber pressure up to +150 mmHg. Diameter and flow were measured in the brachial artery by Doppler ultrasonography. Blood samples were drawn simultaneously from both arms before, during, immediately after and 2 h after the release of the chamber pressure. Plasma levels of endothelin-1 (ET-1), vascular endothelial growth factor A (VEGF-A), fibroblast growth factor 2 (FGF-2) and angiotensin II (Ang-II) were measured. Elevation of chamber pressure by 150 mmHg increased local arterial distending pressure to about 220260 mmHg, resulting in an increase in brachial artery diameter of 9% and flow of 246%. The pressure stimulus increased the plasma levels of ET-1 and Ang-II, but not of VEGF-A or FGF-2 in the test arm. The local release of the vasoconstrictors ET-1 and Ang-II in response to markedly increased distending pressure may reflect one mechanism behind adaptation to acute and long-term changes in intravascular pressure.
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35.
  • Gölster, Helena, 1965-, et al. (författare)
  • Impaired microvascular function related to poor metabolic control in young patients with diabetes
  • 2005
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 25:2, s. 100-105
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the present study was to identify whether young patients with type 1 diabetes using modern multiple insulin injection therapy (MIT) have signs of microvascular dysfunction and to elucidate possible correlations with various disease parameters. Skin blood flow on the dorsum of the foot was measured with laser Doppler perfusion imaging in 37 patients (age 10–21 years, disease duration 6·0–16 years) and 10 healthy controls. Measurements were performed at rest, after change in posture (the leg was lowered below heart level) and during postocclusive hyperaemia. Following a change in posture blood flow increased instead of decreased in a majority of the study subjects. Patients with acute HbA1c >7·5% (n = 22) had an increase in skin blood flow at rest and a significantly reduced blood flow when the leg was lowered below heart level as compared with patients with HbA1c <7·5% (0·26 V versus 0·17 V, P<0·01 and 0·12 V versus 0·23 V, P<0·05, respectively) and healthy controls. Following occlusion of the macrocirculation for 3 min a small non-significant decrease in the hyperaemic response was seen in the patients. The postocclusive hyperaemic response and the venoarteriolar reflex were not correlated to duration of disease, long-term metabolic control or electrophysiological signs of peripheral nerve dysfunction. It is concluded that signs of microvascular dysfunction related to poor metabolic control are present in young patients with MIT treatment and rather well-controlled diabetes. Low resting blood flow levels are suggested to contribute to the absence of postural vasoconstrictor response.
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36.
  • Hedman, Kristofer, et al. (författare)
  • Decreased aerobic capacity 4 years after aortic valve replacement in male patients operated upon for chronic aortic regurgitation
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:3, s. 167-171
  • Tidskriftsartikel (refereegranskat)abstract
    • Exercise testing is underutilized in patients with valve disease. We have previously found a low physical work capacity in patients with aortic regurgitation 6 months after aortic valve replacement (AVR). The aim of this study was to evaluate aerobic capacity in patients 4 years after AVR, to study how their peak oxygen uptake (peakVO2) had changed postoperatively over a longer period of time. Twenty-one patients (all men, 52 +/- 13 years) who had previously undergone cardiopulmonary exercise testing (CPET) pre- and 6 months postoperatively underwent maximal exercise testing 49 +/- 15 months postoperatively using an electrically braked bicycle ergometer. Breathing gases were analysed and the patients physical fitness levels categorized according to angstrom strands and Wassermans classifications. Mean peakVO2 was 22.8 +/- 5.1 ml x kg-1 x min-1 at the 49-month follow-up, which was lower than at the 6-month follow-up (25.6 +/- 5.8 ml x kg-1 x min-1, P = 0.001). All but one patient presented with a physical fitness level below average using angstrom strands classification, while 13 patients had a low physical capacity according to Wassermans classification. A significant decrease in peakVO2 was observed from six to 49 months postoperatively, and the decrease was larger than expected from the increased age of the patients. CPET could be helpful in timing aortic valve surgery and for the evaluation of need of physical activity as part of a rehabilitation programme.
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37.
  • Henareh, Loghman, et al. (författare)
  • Disturbed glucose metabolism is associated with left ventricular dysfunction using tissue Doppler imaging in patients with myocardial infarction
  • 2007
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 27:1, s. 60-66
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: To investigate the association between glucose abnormalities and left ventricular (LV) function assessed by tissue Doppler imaging (TDI) in patients with previous history of myocardial infarction and without known diabetes mellitus. Patients and methods: In a cross-sectional study, 123 patients, aged 31-80 years, with a history of previous myocardial infarction and without known diabetes mellitus were examined with TDI echocardiography. A standard oral glucose test (OGTT) with 75 g of glucose was performed. Results: Two-hour plasma glucose were significantly and negatively associated with TDI parameters such as LV ejection time; early diastolic filling velocity (E'-v); ratio of the early to late diastolic filling velocity (E'/A') and positively associated with regional myocardial performance index (MPI) (P < 0.05). Left ventricular ejection time and MPI were significantly higher; E'/A' and E'-v were significantly lower in patients with disturbed glucose metabolism compared with patients with normal glucose tolerance (P < 0.01). These differences remain significant also when the patients with DM were excluded. Conclusions: The present study demonstrates that disturbed glucose metabolism is associated with more pronounced LV dysfunction using TDI in patients with myocardial infarction. These abnormalities in LV function were more common not only in subjects with diabetes, but also in patients with prediabetic condition, impaired glucose intolerance.
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38.
  • Henriksen, Egil, et al. (författare)
  • Left ventricular end-diastolic geometrical adjustments during exercise in endurance athletes
  • 2008
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 28:2, s. 76-80
  • Tidskriftsartikel (refereegranskat)abstract
    • The increase in left ventricular (LV) end-diastolic volume has recently been shown to explain more than 70% of the increase in stroke volume during upright exercise in endurance athletes. As the end-diastolic volume enhancement not could be explained by an increase in axial cavity length an augmentation in LV short-axis diameters is to be expected. To investigate LV end-diastolic geometrical alterations during exercise, 15 endurance athletes were examined using contrast exercise echocardiography. LV end-diastolic short-axis diameters were made from apical views at several LV cavity levels. From upright rest to upright exercise the LV end-diastolic internal cavity measurements increased significantly. During exercise, the LV cavity became geometrically more spherical with the largest increase in the LV end-diastolic short-axis cavity diameters in the mid and apical parts of the left ventricle. The LV internal long axis showed significant increase from rest to exercise but the absolute increase was small.
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39.
  • Häggmark, Sören, et al. (författare)
  • ST-segment deviations during pacing-induced increased heart rate in patients without coronary artery disease.
  • 2005
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 25:4, s. 246-522
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: In order to interpret ST-segment changes as an indicator of ischemia in patients with higher heart rates (HRs), the relation between ST-segment levels and HR needs to be well defined in subjects without coronary artery disease. METHODS: Eighteen patients with normal ECGs in the catheterization laboratory, after radiofrequency ablation of AV nodal re-entry tachycardia or an accessory pathway were included. Computerized online vectorcardiography (VCG) was performed during step-wise atrial pacing-induced increases in HR up to 150 beats min(-1) (bpm). The ST-vector magnitude (ST-VM) and the relative ST change vector magnitude (STC-VM) were analysed at the J point, J + 20 and J + 60 ms. RESULTS: There was no divergence in the course of ST-VM or STC-VM based on J point + 0, 20, or 60 ms during increasing HR. The STC-VM mean values increased progressively during increases in HR above 100 bpm, with an average increase in STC-VM of 15-20 microV per 10 bpm increases in HR. The ST-VM response during HR increases showed a heterogeneous and unpredictable pattern. CONCLUSION: The STC-VM increases linearly with rising HRs above 100 bpm. The STC-VM can exceed widely recognized ischemic thresholds during higher HRs in the absence of ischemia. The choice of J point time to ST-VM measurements as tested here is not important for the STC-VM relation to HR at these HR levels. Further clinical testing is needed to improve the diagnostic specificity of STC-VM measurements during increased HRs.
  •  
40.
  • Högman, Marieann, et al. (författare)
  • Added value with extended NO analysis in atopy and asthma
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 31:4, s. 294-299
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: Assessments of the usefulness of exhaled nitric oxide (NO) in the treatment of asthma have given conflicting results. It is not always obvious if atopic status has been tested in these evaluations. OBJECTIVES: The aim of the study is to use extended NO analysis to characterize subjects from a random sample populations with focus on rhinitis and asthma. METHODS: Data were extracted from the European Community Respiratory Health Survey II. A subgroup from the Uppsala site that had had their NO measured at multiple flow rates was included (n = 284). The nonlinear model for NO parameters was used. Atopy was defined as having a titre against at least one of the tested allergens ≥0·35 kU l(-1) . Bronchial responsiveness was assessed by methacholine challenge. RESULTS: Subjects with non-atopic rhinitis or non-atopic asthma could not be separated from healthy subjects regarding NO parameters. There was a gradual increase with atopy in airway diffusion rate (D(aw) NO); healthy subject 8·0 (7·3, 8·8), healthy atopic 8·8 (6·7, 11·5), atopic rhinitis 10·6 (9·0, 12·4) and atopic asthma 11·2 (9·9, 28·3) ml s(-1) [geometrical mean (CI(95%) )]. There was a correlation between bronchial responsiveness and D(aw) NO in atopic rhinitis (r = -0·41, P<0·01), and bronchial responsiveness and airway wall content of NO (C(aw) NO) in atopic asthma (r = -0·56, P<0·001). CONCLUSION: It is of importance to characterize atopic status when evaluating the association between NO and asthma. Our results indicate that the use of extended NO analysis, with particular attention to D(aw) NO and C(aw) NO, may be useful in monitoring treatment for rhinitis and asthma.
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41.
  • Högman, Marieann, et al. (författare)
  • Extended NO analysis in a healthy subgroup of a random sample from a Swedish population
  • 2009
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 29:1, s. 18-23
  • Tidskriftsartikel (refereegranskat)abstract
    • INTRODUCTION: There is an interest in modelling exhaled nitric oxide (NO). Studies have shown that flow-independent NO parameters i.e. NO of the alveolar region (C(A)NO), airway wall (C(aw)NO), diffusing capacity (D(aw)NO) and flux (J(aw)NO), are altered in several disease states such as asthma, cystic fibrosis, alveolitis and chronic obsmuctive pulmonary disease (COPD). However, values from a healthy population are missing. OBJECTIVES: To calculate NO parameters in a healthy population by collecting NO values at different exhalation flow rates. METHODS: A random sample from the ECRHS II study was investigated. Among the 281 subjects that had performed a bronchial hyperreactivity (BHR)-test, FEV(1.0), IgE and NO-analyses 89 were found to be healthy. RESULTS: There were no differences in F(E)NO(0.05) or NO parameters between men and women. There were weak correlations between height and both F(E)NO(0.05) (r = 0.23, P = 0.03) and C(aw)NO (r = 0.22, P = 0.04). There was also a correlation between age and C(A)NO (r = 0.28, P = 0.007). When controlled for gender, this correlation was more powerful in women (r = 0.51, P = 0.001) but did not remain for male subjects. CONCLUSION: Extended NO analysis is a simple non-invasive tool that gives by far more information than F(E)NO(0.05). Based on our results, we suggest that the values for healthy subjects should be considered to fall between the following ranges: F(E)NO(0.05), 10-30 ppb; C(aw)NO, 50-250 ppb; D(aw)NO, 5-15 ml s(-1); J(aw)NO, 0.8-1.6 nl s(-1); and C(A)NO, 0-4 ppb. Values outside these intervals indicate the need for further investigation to exclude a state of disease.
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42.
  • Jakobsson, Per, 1948-, et al. (författare)
  • Oxygen supplementation increases glucose tolerance during euglycaemic hyperinsulinaemic glucose clamp procedure in patients with severe COPD and chronic hypoxaemia
  • 2006
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 26:5, s. 271-274
  • Tidskriftsartikel (refereegranskat)abstract
    • Investigations in chronic obstructive pulmonary disease (COPD) patients have shown impaired glucose tolerance in hypoxic COPD patients, compared with COPD patients with normal arterial blood gases. In healthy subjects, hypoxaemia or stay at altitude, have been shown to alter glucose metabolism. At altitude the effect seems to be dependent on duration of stay. A short stay is associated with insulin resistance, a longer stay gives rise to increased glucose uptake. The euglycaemic hyperinsulinaemic glucose clamp technique is a method to study glucose tolerance and enables determinations of glucose clearance in peripheral tissues. We investigated six COPD patients [forced expiratory volume in 1 s 0.7 ± 0.2 l (mean ± SD)] with chronic hypoxaemia (PaO2 7.9 ± 0.6 kPa at rest, breathing air), with and without oxygen supplementation, using the glucose clamp technique. Net peripheral glucose uptake was 5.5 ± 1.2 and 7.1 ± 1.6 mg (kg*min)-1 (+29%) breathing air and supplemental oxygen, respectively (P = 0.03). The tissue sensitivity to insulin increased 32% (P = 0.03) with oxygen supplementation. The results indicate that normalization of oxygen saturation in COPD patients with chronic hypoxaemia may have an immediate effect on glucose tolerance and tissue sensitivity to insulin in these patients. © 2006 Blackwell Publishing Ltd.
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43.
  • Jogestrand, T., et al. (författare)
  • Relation between the elastic properties and intima-media thickness of the common carotid artery
  • 2003
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 23:3, s. 134-137
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the study was to describe the relation between wall elasticity and intima-media thickness in the human carotid artery prior to the development of atherosclerotic plaques. Fifty-eight apparently healthy men, aged 42-65 years (mean 55 years), without symptoms of cardiovascular disease were studied. Thickness and elastic properties of the common carotid artery wall were assessed using ultrasonography and non-invasive arterial pressure measurements. The relation between the calculated intima-media area and the pressure strain elastic modulus was positive and statistically significant on the right but not on the left side. No statistically significant relations were found between the calculated intima-media area and the stiffness or between the intima-media thickness and the elastic modulus or stiffness on either side. Thus, the relations between the common carotid artery intima-media thickness/calculated intima-media area and the common carotid artery elastic modulus/stiffness are weak. In regions without atherosclerotic plaques, the elastic properties of the human carotid artery wall do not seem to be influenced by the wall thickness in an important way.
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44.
  • Jorstig, Stina Hellstrandh, 1978-, et al. (författare)
  • Calculation of right ventricular stroke volume in short-axis MR images using the equation of the tricuspid plane
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - Malden, USA : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:1, s. 5-11
  • Tidskriftsartikel (refereegranskat)abstract
    • Short-axis (SA) magnetic resonance (MR) images are commonly planned parallel to the left atrioventricular valve. This orientation leads to oblique slices of the right ventricle (RV) with subsequent difficulties in separating the RV from the right atrium in the SA images. The insertion points of the tricuspid valve (TV) in the myocardium can be clearly identified in the right ventricle long axis (RVLA) and four-chamber (4CH) views. The purpose of this study was to develop a method that transfers the position of the tricuspid plane, as seen in the RVLA and 4CH views, to the SA images to facilitate the separation of the RV from the atrium. This methodology, termed Dissociating the Right Atrium from the Ventricle Volume (DRAW), was applied in 20 patients for calculations of right ventricular stroke volume (RVSV). The RVSV using DRAW (RVSVDRAW) was compared to left ventricular stroke volumes (LVSV) obtained from flow measurements in the ascending aorta. The RVSV was also determined using the conventional method (RVSVCONV) where the stack of images from the SA views are summarized, and a visual decision is made of the most basal slice to be included in the RV. The mean difference between RVSVDRAW and LVSV was 0.1 +/- 12.7 ml, while the mean difference between RVSVCONV and LVSV was 0.33 +/- 14.3 ml. Both the intra- and interobserver variability were small using the DRAW methodology, 0.6 +/- 3.5 and 1.7 +/- 2.7 ml, respectively. In conclusion, the DRAW method can be used to facilitate the separation of the RV and the atrium.
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45.
  • Järhult, Susann J., 1971-, et al. (författare)
  • Brachial artery hyperemic blood flow velocities are related to carotid atherosclerosis
  • 2009
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 29:5, s. 360-365
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: Cardiovascular (CV) risk relates to the blood flow velocity pattern in the brachial artery during hyperemia, especially to the hyperaemic systolic to diastolic mean blood flow velocity (SDFV) ratio. Here, we investigated the relations between SDFV in the brachial artery and different characteristics of carotid atherosclerosis. MATERIAL AND METHODS: Data were collected from 1016 70-year-olds participating in the Prospective Investigation of Uppsala Seniors study. Doppler recordings of blood flow velocity during hyperemia were analysed in the brachial artery. In the carotid artery, intima-media thickness (IMT) was recorded together with an assessment of echogenicity by the Grey scale median (GSM) method in both overt plaques and in the intima-media complex (IM-GSM). RESULTS: The SDFV ratio was related to the number of carotid arteries affected by plaque (P = 0.018) and inversely to plaque echogenicity (P = 0.0003). The SDFV ratio was also related to IMT (P = 0.0022) and inversely to IM-GSM (P = 0.0001). These relations were statistically significant also after adjusting for major CV risk factors, individually as well as summarised as the Framingham risk score. CONCLUSION: Our results indicate that the hyperemic systolic to diastolic blood flow velocity ratio in the brachial artery is related to atherosclerosis in the carotid artery.
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46.
  • Järhult, Susann J, 1971-, et al. (författare)
  • Brachial artery hyperemic blood flow velocity in relation to established indices of vascular function and global atherosclerosis
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 32:3, s. 227-233
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • BackgroundSystolic to diastolic blood flow velocity (SDFV) ratio in the Brachial artery recently proved to be related to cardiovascular risk and Carotid atherosclerosis. We hypothesized that the SDFV ratio was related to established markers of vascular function and global atherosclerosis.  MethodsEstablished markers of endothelial function in forearm resistance vessels, flow-mediated vasodilation and arterial stiffness were assessed in the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study including 1016 individuals aged 70. Whole body magnetic resonance angiography was performed in a random 306 of the participants. Atherosclerotic lesions were summarized in a total atherosclerotic score (TAS). Before and during hyperemia of the Brachial artery, systolic and diastolic blood flow velocities were measured by Doppler. Results The SDFV ratio was positively related to endothelium-independent vasodilatation, while inverse relations to flow-mediated dilation, common carotid artery distensibility and the stroke volume to pulse pressure ratio were found. Endothelium-dependent vasodilatation and total peripheral resistance index were not significantly related to the SDFV ratio.The SDFV ratio (p=0.015) and the blood flow increase during hyperemia (p= 0.020) were both significantly related to TAS after gender adjustment. When adjusted for the Framingham risk score, both the SDFV ratio (p= 0.057) and blood flow increase (p= 0.078) lost somewhat in significance. ConclusionThe SDFV ratio was related to established markers of both vasodilation and arterial compliance, and to global atherosclerosis. Future larger studies have to evaluate if the SDFV ratio is related to global atherosclerosis independently of traditional risk factors.
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47.
  • Järhult, Susann J., 1971-, et al. (författare)
  • Hyperaemic blood-flow velocities in systole and diastole relate to coronary risk in divergent ways
  • 2008
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 28:3, s. 189-95
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: A recent study suggested blood-flow velocity in diastole during reactive hyperaemia as a major driver of flow-mediated vasodilation (FMD) of the brachial artery, also being related to cardiovascular risk factors. The present study aimed to investigate the relative importance of hyperaemic systolic and diastolic blood-flow velocity in the forearm regarding both FMD and cardiovascular risk factors. METHODS: In the Prospective Investigation of the Vasculature in Uppsala Seniors study, conducted in 1016 subjects aged 70 years, FMD, systolic and diastolic blood hyperaemic flow velocities in the brachial artery were evaluated by ultrasound. RESULTS: Hyperaemic blood-flow velocity both in systole and diastole were related to FMD (r = 0.14-0.19, P<0.0001). However, while hyperaemic systolic blood-flow velocity was related to coronary risk (Framingham risk score) in a positive way (r = 0.08, P = 0.013), diastolic blood-flow velocity was inversely related to coronary risk (r = -0.08, P = 0.016). Therefore, the systolic to diastolic hyperaemic blood-flow velocity ratio was more powerful related to coronary risk (r = 0.23, P = 0.0001). In a multiple regression model, both FMD and the systolic to diastolic hyperaemic blood-flow velocity ratio were independent predictors of coronary risk (P = 0.018 and P = 0.0001). CONCLUSION: As hyperaemic blood-flow velocities in systole and diastole in the brachial artery were related to coronary risk in divergent ways, the ratio thereof is a promising index of vascular function providing independent information regarding coronary risk when compared with FMD.
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48.
  • Kajiura, M., et al. (författare)
  • Variant autonomic regulation during active standing in Swedish and Japanese junior high school children
  • 2008
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 28:3, s. 174-181
  • Tidskriftsartikel (refereegranskat)abstract
    • The present investigation is about cardiovascular responses and relevant autonomic function in Swedish and Japanese pubertal children on active standing using non-invasive continuous beat-to-beat finger arterial pressure (FAP) monitoring and power spectral analysis. Examined were 54 Swedish and 57 Japanese children (13-15 years). FAP and heart rate (HR) was continuously recorded in the supine position and during standing. Supine FAP was significantly higher in Swedish compared with Japanese children (121/62 versus 103/53 mmHg, P < 0.001). Swedish children showed a higher increase in arterial pressure and HR upon uprising, resulting in a higher vasoconstrictor index (5.04 ± 0.22 versus 2.31 ± 0.11 mmHgs-1, P < 0.001, respectively). There were also higher increases in arterial pressure and HR in the following steady state period (1-7min) between the two groups. These differences were also found after adjustment of body weight and height. Frequency domain analysis of HR and arterial pressure variability indicated significantly higher low/high frequency power of HR and low frequency power of arterial pressure. These results suggest that Swedish pubertal children have higher basal blood pressure and enhanced cardiovascular sympathetic responses. These differences in the two cohorts might be caused by genetic factors. © 2008 The Authors Journal compilation © 2008 Scandinavian Society of Clinical Physiology and Nuclear Medicine.
  •  
49.
  • Keramidas, Michail E., et al. (författare)
  • The effect of interval training combined with thigh cuffs pressure on maximal and submaximal exercise performance
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:3, s. 205-213
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of the study was to investigate the effect of interval training combined with a thigh cuffs pressure of +90 mmHg on maximal and submaximal cycling performance. Twenty untrained individuals were assigned either to a control (CON) or to an experimental (CUFF) training group. Both groups trained 3 days per week for 6 weeks at the same relative intensity; each training session consisted of 2-min work bout at 90% of VO(2max): 2-min active recovery bout at 50% of VO(2max). An incremental exercise test to exhaustion, a 6-min constant-power test at 80% of VO(2max) (Sub(80)) and a maximal constant-power test to exhaustion (TF(150)) were performed pre- and post-training. Despite the unchanged VO(2max), both groups significantly increased peak power output (CON: ∼12%, CUFF: ∼20%) that was accompanied by higher deoxygenation (ΔStO(2)) measured with near-infrared muscle spectroscopy. These changes were more pronounced in the CUFF group. Moreover, both groups reduced VO(2) during the Sub(80) test without concomitant changes in ΔStO(2). TF(150) was enhanced in both groups. Thus, an interval exercise training protocol under moderate restricted blood flow conditions does not provide any additive effect on maximal and submaximal cycling performance. However, it seems to induce peripheral muscular adaptations, despite the lower absolute training intensity.
  •  
50.
  • Kesek, Milos, et al. (författare)
  • Heart rate variability during sleep and sleep apnoea in a population based study of 387 women
  • 2009
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 29:4, s. 309-315
  • Tidskriftsartikel (refereegranskat)abstract
    • Increased sympathetic activity during sleep has been suggested as a link between obstructive sleep apnoea syndrome and cardiovascular disease. Heart rate variability (HRV) is a measure of autonomic effect on the heart. Different parameters have been associated with sympathetic and parasympathetic activity. We have studied HRV in different sleep stages and related the HRV-pattern to sleep apnoea in a population-based sample of 387 women. We investigated the HRV-parameters standard deviation of all R-R intervals (SDNN), root of the averaged square of successive differences (RMSSD), low frequency component (LF), high frequency component (HF), ratio of low frequency component to high frequency component LF/HF and VSAI [variation in sympathetic activity between rapid eye movement (REM) and slow wave sleep, defined as LF(REM)-LF(SWS)]. The HRV-parameters were compared with the results of a full-night polysomnography. Hourly incidence of obstructive episodes was used for classifying the subjects into four apnoea-hypopnoea index (AHI)-groups (<5, > or =5 and <15, 15-30 and >30 events). Individual sleep stages were analysed by pooling all recordings. Women with high AHI had higher heart rate and LF/HF ratio. In subjects with AHI >30, LF/HF ratio however dropped to same level as with AHI <5. Subjects with high AHI had low VSAI. Levels of SDNN, LF and LF/HF ratio during REM and light sleep were similar to wakefulness. In slow wave sleep the parameters decreased. In conclusion, moderately increased prevalence of obstructive apnoeas was associated with signs of higher sympathetic activity. High AHI was however associated with a HRV-pattern suggestive of depressed sympathetic drive and lowered ability to increase it during REM.
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