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Sökning: L773:1475 0961 > (2010-2014)

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1.
  • 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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2.
  • 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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3.
  • 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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4.
  • 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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5.
  • Brudin, Lars, et al. (författare)
  • Comparison of two commonly used reference materials for exercise bicycle tests with a Swedish clinical database of patients with normal outcome
  • 2014
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 34:4, s. 297-307
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Reference values for working capacity, blood pressure, heart rate, perceived exertion, etc. during bicycle exercise tests have been sought after for many years. This is because earlier commonly used reference values for physical work capacity have been either too low or too high when compared to the clinical experience of several Swedish departments of clinical physiology. The aim of the study was to compare two commonly used reference materials with normal outcomes from a clinical database. Methods: Data from a clinical database of standardized exercise tests in Kalmar, Sweden, between 2004 and 2012, and having been judged as normal, were divided into 5-year categories of 5-10 to 75-80 years of age covering people from 7 to 80 years of age. Results: Maximal working capacity (W-max), maximal heart rate, maximal systolic blood pressure and maximal perceived exertion are presented for each of the 15 age categories. Regression equations are also presented for each sex with age and height as independent predictors. Quantitative comparisons of W-max are calculated for the three materials and possible explanations discussed. Conclusions: Values of W-max lie between the two reference materials most commonly used in Sweden. In addition, the present material covers subjects aged 7-19 years.
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6.
  • 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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7.
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8.
  • 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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9.
  • 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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10.
  • 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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11.
  • 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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12.
  • 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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13.
  • 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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14.
  • 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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16.
  • Johnson, Jonas, et al. (författare)
  • The early diastolic myocardial velocity : A marker of increased risk in patients with coronary heart disease
  • 2014
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 34:5, s. 389-396
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: Tissue Doppler imaging (TDI) is a promising echocardiographic modality allowing quantification of myocardial performance. However, the prognostic potential of TDI in patients with acute myocardial infarction (AMI) is not yet investigated. We sought to explore the ability of TDI in identifying patients at risk for new cardiovascular events after AMI. Methods: One hundred and nineteen patients with AMI were recruited prospectively (mean age 61 years; range 32-81 years of age). Patients with diabetes mellitus (DM) were excluded. Echocardiography was performed 3-12 months after AMI. Two-dimensional (2-D) and TDI variables were recorded. The patients were followed during a mean period of 4·6 years (range 1-8 years). The primary end-point was defined as any of the following: death from any cause, non-fatal reinfarction or stroke, unstable angina pectoris, congestive heart failure requiring hospitalization and coronary revascularization procedure. Results: Thirty patients had some form of cardiovascular events during follow-up. Seven patients had cardiovascular death, 13 patients had reinfarction and four patients had a stroke. New angina or unstable angina was recorded in 21 patients. Of these patients, 13 underwent percutaneous coronary angioplasty (PCI) or coronary artery bypass grafting (CABG). The early diastolic myocardial velocity (Em) emerged as the only echocardiographic variable that offered a clear differentiation between patients that presented with new cardiovascular (CV) events as compared to the corresponding group without any CV events at follow-up (P<0·05). In multivariate statistical analysis and after adjustment for age, sex, total cholesterol, body mass index (BMI) and other baseline characteristics, Em remained as independent predictors of CV events (HR, 1·18, 95% CI, 1·02-1·36; P<0·05). However, none of the investigated variables evolved as an independent predictor of cardiovascular morbidity and mortality. Conclusion: Em appears to be a sensitive echocardiographic index in identifying non-diabetic patients with AMI at risk of new cardiovascular events.
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17.
  • 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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18.
  • 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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19.
  • Keramidas, Michail E., et al. (författare)
  • Forearm-finger skin temperature gradient as an index of cutaneous perfusion during steady-state exercise
  • 2013
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 33:5, s. 400-404
  • Tidskriftsartikel (refereegranskat)abstract
    • The purpose of this study was to examine whether the forearm-finger skin temperature gradient (Tforearm-finger), an index of vasomotor tone during resting conditions, can also be used during steady-state exercise. Twelve healthy men performed three cycling trials at an intensity of similar to 60% of their maximal oxygen uptake for 75min separated by at least 48h. During exercise, forearm skin blood flow (BFF) was measured with a laser-Doppler flowmeter, and finger skin blood flow (PPG) was recorded from the left index fingertip using a pulse plethysmogram. Tforearm-finger of the left arm was calculated from the values derived by two thermistors placed on the radial side of the forearm and on the tip of the middle finger. During exercise, PPG and BFF increased (P<0.001), and Tforearm-finger decreased (P<0.001) from their resting values, indicating a peripheral vasodilatation. There was a significant correlation between Tforearm-finger and both PPG (r=-0.68; P<0.001) and BFF (r=-0.50; P<0.001). It is concluded that Tforearm-finger is a valid qualitative index of cutaneous vasomotor tone during steady-state exercise.
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20.
  • 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.
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21.
  • Kindberg, Katarina, 1977-, et al. (författare)
  • Temporal 3D Lagrangian strain from 2D slice followed cine DENSE MRI
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:2, s. 139-144
  • Tidskriftsartikel (refereegranskat)abstract
    • A quantitative analysis of myocardial mechanics is fundamental to the understanding of cardiac function, diagnosis of heart disease and assessment of therapeutic intervention. In the clinical situation, where limited scan time often is important, a detailed analysis of the myocardium in a specific region might be more applicable than a full 3D measurement of the entire left ventricle. This paper presents a method to obtain temporal evolutions of transmural 3D Lagrangian strains from two intersecting 2D planes of slice followed cine displacement encoding with stimulated echoes (DENSE) data using a bilinear-cubic polynomial element to resolve strain from the displaced myocardial positions. The method demonstrates accurate results when validated in an analytical model, and has been applied to in vivo data acquired on a 3 T magnetic resonance (MR) system from a healthy volunteer to quantify systolic strains at the anterior-basal region of left ventricular myocardium. The in vivo results agree within experimental accuracy with values reported in the literature.
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22.
  • Kronander, Håkan, et al. (författare)
  • Diagnostic performance and partition values of exercise electrocardiographic variables in the detection of coronary artery disease - improved accuracy by using ST/HR hysteresis
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:2, s. 98-106
  • Tidskriftsartikel (refereegranskat)abstract
    • P>Exercise electrocardiography is widely used for initial identification of patients with coronary artery disease (CAD). This study compares the measurements of ST-segment changes during exercise and during early postexercise recovery in terms of diagnostic discrimination capacity and optimal partition values. Data from 1876 patients undergoing a routine bicycle exercise test were analysed. CAD was angiographically verified in 668 patients, and excluded by angiography (n = 119), myocardial scintigraphy (n = 250), and on clinical grounds (n = 839) in 1208 patients. Postexercise ST/HR hysteresis was calculated as normalized for heart rate (HR) ST/HR loop area during the first 3 min of recovery. ST/HR index was obtained by dividing the overall ST amplitude change during exercise by exercise-induced HR change, and ST/HR slope was calculated using linear regression analysis of ST/HR data pairs during exercise. ST-segment depression was measured during, and for 3 min after the exercise. Discriminating capacity of the methods was evaluated in terms of receiver operating characteristic areas and optimal partition values providing the combination of the best sensitivity and specificity were established. The best diagnostic discrimination was provided by ST/HR hysteresis at optimal partition value of -15 mu V, followed by postexercise ST amplitude measurements at gender-specific partition values of -10 to -90 mu V, ST/HR slope [partition value 2 center dot 4 mu V (beats/min)-1], ST/HR index [partition value 1 center dot 6 mu V (beats/min)-1], and ST-segment depression during exercise (partition value 70 mu V in men and 90 mu V in women). The results demonstrate that analysis of postexercise ST/HR hysteresis offers the most accurate and gender indifferent identification of patients with CAD.
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23.
  • Kvitting, J.P., et al. (författare)
  • Analysis of human myocardial dynamics using virtual markers based on magnetic resonance imaging
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:1, s. 23-29
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Myocardial dynamics are three-dimensional (3D) and time-varying. Cineradiography of surgically implanted makers in animals or patients is accurate for assessing these events, but this invasive method potentially alters myocardial motion. The aim of the study was to quantify myocardial motion using magnetic resonance imaging (MRI) and hence to provide a non-invasive approach to characterize 3D myocardial dynamics. Methods: Myocardial motion was quantified in ten normal volunteers by tracking the Lagrangian motion of individual points (i.e. virtual markers), based on time-resolved 3D phase-contrast MRI data and Fourier tracking. Nine points in the myocardium were tracked over the entire cardiac cycle, allowing a wire frame model to be generated and systolic and diastolic events identified. Results: Radius of curvature of the left ventricular (LV) wall was calculated from the virtual markers; the ratio between the anterior–posterior (AP) and septal–lateral (SL) walls in the LV shows an oval shape of the apical short axis plane at end systole (ES) and more circular at end diastole (ED). The AP/SL ratio for the basal plane shows an oval shape at ES and ED. We found that the rotation of the basal plane in ES was less compared to the apical plane [−2·0 ± 2·2 versus 4·1 ± 2·6 degrees (P<0·005)]. The apical plane rotated counter clock wise as viewed from the apex. Conclusion: This new non-invasive tool, despite current limitations in temporal and spatial resolution, may provide a comprehensive set of virtual myocardial markers throughout the entire LV without the confounding effects introduced by surgical implantation.
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24.
  • Laaksonen, Marko, 1975-, et al. (författare)
  • Perfusion heterogeneity does not explain excess muscle oxygen uptake during variable intensity exercise
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:4, s. 241-249
  • Tidskriftsartikel (refereegranskat)abstract
    • The association between muscle oxygen uptake (VO2) and perfusion or perfusion heterogeneity (relative dispersion, RD) was studied in eight healthy male subjects during intermittent isometric (1 s on, 2 s off) one-legged knee-extension exercise at variable intensities using positron emission tomography and a-v blood sampling. Resistance during the first 6 min of exercise was 50% of maximal isometric voluntary contraction force (MVC) (HI-1), followed by 6 min at 10% MVC (LOW) and finishing with 6 min at 50% MVC (HI-2). Muscle perfusion and O2 delivery during HI-1 (26 ± 5 and 5·4 ± 1·0 ml 100 g−1 min−1) and HI-2 (28 ± 4 and 5·8 ± 0·7 ml 100 g−1 min−1) were similar, but both were higher (P<0·01) than during LOW (15 ± 3 and 3·0 ± 0·6 ml 100 g−1 min−1). Muscle VO2 was also higher during both HI workloads (HI-1 3·3 ± 0·4 and HI-2 4·1 ± 0·6 ml 100 g−1 min−1) than LOW (1·4 ± 0·4 ml 100 g−1 min−1; P<0·01) and 25% higher during HI-2 than HI-1 (P<0·05). O2 extraction was higher during HI workloads (HI-1 62 ± 7 and HI-2 70 ± 7%) than LOW (45 ± 8%; P<0·01). O2 extraction tended to be higher (P = 0·08) during HI-2 when compared to HI-1. Perfusion was less heterogeneous (P<0·05) during HI workloads when compared to LOW with no difference between HI workloads. Thus, during one-legged knee-extension exercise at variable intensities, skeletal muscle perfusion and O2 delivery are unchanged between high-intensity workloads, whereas muscle VO2 is increased during the second high-intensity workload. Perfusion heterogeneity cannot explain this discrepancy between O2 delivery and uptake. We propose that the excess muscle VO2 during the second high-intensity workload is derived from working muscle cells.
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25.
  • Lattuada, Marco, et al. (författare)
  • Evaluating abdominal oedema during experimental sepsis using an isotope technique
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 32:3, s. 197-204
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: Abdominal oedema is common in sepsis. A technique for the study of such oedema may guide in the fluid regime of these patients. Procedures: We modified a double-isotope technique to evaluate abdominal organ oedema and fluid extravasation in 24 healthy or endotoxin-exposed (septic) piglets. Two different markers were used: red blood cells (RBC) labelled with Technetium99m (99mTc) and Transferrin labelled with Indium111 (111In). Images were acquired on a dual-head gamma camera. Microscopic evaluation of tissue biopsies was performed to compare data with the isotope technique. Results: No 99mTc activity was measured in the plasma fraction in blood sampled after labelling. Similarly, after molecular size gel chromatography, 111In activity was exclusively found in the high molecular fraction of the plasma. Extravasation of transferrin, indicating the degree of abdominal oedema, was 4 06 times higher in the LPS group compared to the healthy controls (P< 0 0001). Abdominal free fluid, studied in 3 animals, had as high 111In activity as in plasma, but no 99mTc activity. Intestinal lymphatic vessel size was higher in LPS (3 7 +/- 1 1 lm) compared to control animals (0 6 + 0 2 lm; P< 0 001) and oedema correlated to villus diameter (R 2 = 0 918) and lymphatic diameter (R 2 = 0 758). A correlation between a normalized index of oedema formation (NI) and intra-abdominal pressure (IAP) was also found: NI = 0 46* IAP) 3 3 (R2 = 0 56). Conclusions: The technique enables almost continuous recording of abdominal oedema formation and may be a valuable tool in experimental research, with the potential to be applied in the clinic.
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26.
  • Lind, Lars (författare)
  • A combined test of acetylcholine-mediated vasodilation of both the forearm resistance vessels and the radial artery
  • 2013
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 33:3, s. 206-210
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective To evaluate a new combined test of endothelium-dependent vasodilation (EDV) in the forearm resistance vessel and the radial artery. Methods Acetylcholine (ACh) and sodium nitroprusside (SNP) infusion in the brachial artery were used to simultaneous evaluate EDV and endothelium-independent vasodilation (EIDV) in forearm resistance vessels (plethysmography) and in the radial artery (ultrasound) in 76 healthy subjects. Brachial artery ultrasound was used to assess flow-mediated vasodilation (FMD). Results Acetylcholine induced a 4 center dot 5% (median value, P=0 center dot 0010) increase in the radial artery diameter, while SNP induced a 31 center dot 2% increase in diameter (P<0 center dot 0001). While no increase in radial artery blood flow was induced by ACh (P=0 center dot 69), an increase by 181% in radial blood flow was induced by SNP (P<0 center dot 0001). When relating the radial artery diameter data to FMD, the change in radial artery diameter induced by ACh was significantly correlated with FMD (r=0 center dot 35, P=0 center dot 013). No such relationship was seen for the diameter change induced by SNP (r=0 center dot 03, P=0 center dot 81). When relating the radial artery blood flow data to EDV and EIDV, the change in radial artery blood flow induced by ACh was significantly correlated with EDV in an inverse fashion (r=0 center dot 42, P=0 center dot 0032). No such relationship was seen for the blood flow change induced by SNP when related to EIDV (r=0 center dot 07, P=0 center dot 63). Conclusion Simultaneous measurements of blood flow in forearm vessels by plethysmography and in the radial artery by ultrasound during ACh infusion is a new way to assess EDV in both resistance and conduit arteries during one investigation.
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27.
  • Lind, Lars (författare)
  • Arterial stiffness, but not endothelium-dependent vasodilation, is related to a low Ankle-Brachial index
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 31:3, s. 182-187
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Arterial compliance and endothelium-dependent vasodilation are two characteristics of the vessel wall. In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study we studied the relationships between arterial compliance and endothelium-dependent vasodilation versus the Ankle-Brachial index (ABI), a clinically used index of peripheral artery disease. Methods: In the population-based PIVUS study (all aged 70), arterial compliance was determined by ultrasound as the distensibility of the carotid artery and the stroke volume to pulse pressure (SV/PP) ratio by echocardiography, while endothelium-dependent vasodilation was assessed by the invasive forearm technique with acetylcholine (EDV) and brachial artery ultrasound (FMD) in 519 subjects in whom the Ankle-Brachial index was investigated. Results: After adjustments for gender and Framingham risk score, distensibility in the carotid artery and the SV/PP ratio were significantly reduced in subjects with a reduced ABI (<0·9) in both legs (n = 15, P = 0·0006 and P = 0·0003, respectively). Endothelium-dependent vasodilation was not significantly related to a reduced ABI. Conclusion: A reduced arterial compliance, but not endothelium-dependent vasodilation, was related to a low ABI in both legs after adjustment for major risk factors, suggesting that atherosclerosis in the leg arteries is associated with arterial compliance also in other parts of the vasculature.
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28.
  • Lind, Lars, et al. (författare)
  • The echogenicity of the intimamedia complex in the common carotid artery is related to insulin resistance measured by the hyperinsulinemic clamp in elderly men
  • 2013
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 33:2, s. 137-142
  • Tidskriftsartikel (refereegranskat)abstract
    • The echogenicity of the intimamedia complex (IM-GSM) has recently been shown to be related to the echogenicity in carotid artery plaque and to predict cardiovascular (CV) mortality. The present study aims to evaluate the relationship between metabolic CV risk factors, with special emphasis on insulin resistance, and IM-GSM in the carotid artery. Carotid artery ultrasound with grey-scale median analysis of the intimamedia complex, IM-GSM, was performed in a population sample of 480 men aged 75years. In these subjects, a euglycemic hyperinsulinemic clamp to investigate insulin resistance was performed together with measurements of conventional CV risk factors at the age of 70. The metabolic syndrome (MetS) was defined by the NCEP/ATPIII-criteria. In univariate analysis, IM-GSM in the common carotid artery was inversely correlated with the intimamedia thickness (IMT), body mass index (BMI), waist/hip ratio, fasting glucose, serum triglycerides, low HDL cholesterol and insulin resistance at the clamp (r=0 center dot 24, P<0 center dot 001). In multiple regression analysis, only insulin resistance at the clamp and BMI were independently related to IM-GSM. Subjects with the MetS (22%) showed a reduced IM-GSM when compared to those without (64 +/- 20 SD versus 68 +/- 19, P<0 center dot 05). Because the echogenicity of the intimamedia complex in the carotid artery is related to obesity and insulin resistance at clamp independently of IMT, this new vascular characteristic would serve as a marker of vascular alterations induced by insulin resistance and the MetS and has the advantage to be obtainable in almost all subjects.
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29.
  • Loiske, Karin, 1978-, et al. (författare)
  • Left and right ventricular systolic long-axis function and diastolic function in patients with takotsubo cardiomyopathy
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - Oxford : Wiley. - 1475-0961 .- 1475-097X. ; 31:3, s. 203-208
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: Takotsubo cardiomyopathy is characterized by apical wall motion abnormalities without coronary stenosis. Limited information is available on the genesis of the underlying reversible contractile disorder. Our objective in this prospective study was to investigate biventricular changes in systolic long-axis function and diastolic parameters in the acute phase and after recovery.Methods and results: Thirteen consecutive patients were examined by echocardiography and coronary angiography at admission and again by echocardiography after 3 months. Amplitudes, systolic and diastolic velocities of the mitral and tricuspid annuli and conventional diastolic parameters were measured. Systolic long-axis shortening of the left ventricle (LV) and right ventricle (RV) improved from 9·6 ± 2·2 mm to 11·2 ± 1·9 mm (P = 0·02) and from 21·3 ± 3·6 mm to 24·1 ± 2·8 mm (P = 0·02), respectively. LV systolic, early and late diastolic velocities measured by pulsed-wave tissue Doppler also improved, while additional conventional diastolic parameters of the LV and RV diastolic function were unchanged.Conclusions: Takotsubo cardiomyopathy temporarily affects systolic LV and RV function, while most diastolic parameters remain unchanged
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30.
  • Lundberg, Christina, et al. (författare)
  • The relationship between carotid intima-media thickness and global atherosclerosis
  • 2014
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 34:6, s. 457-462
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND:The aim of this study was to investigate the relationship between (i) carotid intima-media thickness (CIMT) at baseline as well as (ii) change in CIMT over 5 years (ΔCIMT) and atherosclerotically induced luminal narrowing in non-coronary arterial territories assessed by whole-body magnetic resonance angiography (WBMRA).METHODS AND RESULTS:In subgroups of the Prospective Investigation of Vasculature in Uppsala Seniors (PIVUS) study, US measurements of CIMT in the common carotid arteries were analysed at 70 and 75 years and ΔCIMT was calculated (n = 272). WBMRA, assessing arterial stenosis in five different territories by which also a total atherosclerotic score (TAS) was calculated, was performed at 70 years (n = 306).RESULTS:Carotid intima-media thickness in the carotid artery at baseline was correlated with TAS (P = 0·0001) when adjusted to a set of traditional risk factors for atherosclerosis, as well as to stenosis in two of the different investigated territories (aorta and lower leg, P = 0·013 and P = 0·004), but there was no significant correlation between ΔCIMT and TAS (P = 0·41).CONCLUSIONS:In the present study, CIMT, but not ΔCIMT over 5 years, in the carotid artery was related to overall stenoses in the body, as assessed by WBMRA. These findings support CIMT as a general marker for atherosclerosis.
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31.
  • Modin, Daniel, et al. (författare)
  • Evaluation of Aortic Geometries created by MRI Data in Man
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 31:6, s. 485-491
  • Tidskriftsartikel (refereegranskat)abstract
    • The development of atherosclerotic plaques has been associated with the patterns of wall shear stress (WSS). However, much is still uncertain with the methods used to calculate WSS. Correct vessel geometries are mandatory to get reliable estimations and the purpose of this study was to evaluate an in vivo method for creating aortic 3D geometry in man based on data from magnetic resonance imaging (MRI) with ultrasound as reference.Methods: The aortas of ten healthy males, 23.4 ± 1.6 years of age, were examined with MRI, and 3D geometries were created with manual segmentation of the images. Lumen diameters (LD) were measured in the abdominal aorta (AA) and the thoracic aorta (TA) with non-invasive B-mode ultrasound as a reference.Results: The anteroposterior diameter of the AA was 13.6 ± 1.1 mm for the MRI and 13.8 ± 1.3 mm for the ultrasound (NS). Intraobserver variability (CV) for MRI and ultrasound was <0.92% and <0.40% respectively . Interobserver variability MRI and ultrasound was 0.96% and 0.56% respectively. The diameter of the TA was 19.2 ± 1.4 mm for the MRI, and the intraobserver variability (CV) were <0.78% and interobserver variability (CV) were 0.92%.Conclusion: Specific arterial geometries can be constructed with a high degree of accuracy using MRI. This indicate that the MRI geometries may be used to create realistic and correct geometries in the calculation of WSS in the aorta of man.
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32.
  • Renner, Johan, et al. (författare)
  • Subject-specific aortic wall shear stress estimations using semi-automatic segmentation
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:6, s. 481-491
  • Tidskriftsartikel (refereegranskat)abstract
    • Atherosclerosis development is strongly believed to be influenced by hemodynamic forces such as wall shear stress (WSS). To estimate such an entity in-vivo in humans, image-based computational fluid dynamics (CFD) is a useful tool. In this study, we use a combination of magnetic resonance imaging (MRI) and CFD to estimate WSS. In such method, a number of steps are included. One important step is the interpretation of images into 3D models, named segmentation. The choice of segmentation method can influence the resulting WSS distribution in the human aorta. This is studied by comparing WSS results gained from the use of two different segmentation approaches: manual and semi-automatic, where the manual approach is considered to be the reference method. The investigation is performed on a group of eight healthy male volunteers. The different segmentation methods give slightly different geometrical depictions of the human aorta (difference in the mean thoracic Aorta lumen diameter were 0.7% Pandlt;0.86). However, there is a very good agreement between the resulting WSS distribution for the two segmentation approaches. The small differences in WSS between the methods increase in the late systole and early diastolic cardiac cycle time point indicating that the WSS is more sensitive to local geometric differences in these parts of the cardiac cycle (correlation coefficient is 0.96 at peak systole and 0.68 at early diastole). We can conclude that the results show that the semi-automatic segmentation method can be used in future to estimate relevant aortic WSS.
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33.
  • Rosendahl, Lene, et al. (författare)
  • Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation : A comparison of two imaging protocols
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 30:2, s. 122-129
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady-state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction.Methods: Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non-infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed.Results: SS_SSFP had significantly better quality scores in all categories (P = 0·037, P = 0·014, P = 0·021, P = 0·03). SNRinfarct and SNRblood were significantly better for IR_FGRE than for SS_SSFP (P = 0·048, P = 0·018). No significant difference was found in SNRmyocardium and CNR. The myocardial volume was significantly larger with SS_SSFP (170·7 versus 159·2 ml, P<0·001), but no significant difference was found in infarct volume and infarct extent.Conclusion: SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.
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34.
  • Schmekel, Birgitta, et al. (författare)
  • Serum lysozyme a surrogate marker of pulmonary microvascular injury in smokers?
  • 2013
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 33:4, s. 307-312
  • Tidskriftsartikel (refereegranskat)abstract
    • Progression rate of disease processes in smoke-induced lung injuries varies greatly. Diverse pathophysiological mechanisms may trigger these divergences. The aim of this study was to evaluate whether circulating markers of monocytes/macrophages and/or neutrophil [i.e. lysozyme (LZM) or myeloperoxidase (MPO)] were associated with reduced values of diffusion capacity (DL,CO), which is considered to serve as a mirror of pulmonary microvascular derangement and an early sign of tissue remodelling in smokers. Data obtained from 134 smokers (GOLD stage 1) and 24 matched healthy non-smoking volunteers were evaluated in a cross-sectional study design. Lung function tests as well as single breath test of DL,CO were assessed according to ATS/ERS guidelines. Biomarkers were measured in serum by means of sensitive immunoassays. A subgroup of smokers with normal lung function was created to minimize confounding, by excluding datasets showing significant airflow limitation and abnormally high values of carboxy haemoglobin (COHb), the latter indicating recent smoking. The capacity of serum lysozyme to correctly identify abnormally low values of DL,CO (i.e. andlt;1 center dot 9SD units), tended to be higher than that of Myeloperoxidase as assessed by analyses of receiver operated curves (ROC; AUC 0 center dot 81, 95%CI: 0 center dot 690 center dot 89 versus AUC 0 center dot 67, 95%CI: 0 center dot 600 center dot 81). It is concluded that serum levels of lysozyme, reflecting mainly activated monocytes/macrophages but also neutrophils, were significantly associated with isolated decrements of DL,CO in smokers with normal lung function tests. This suggests monocytes/macrophages to have a significant mechanistic role in early phases of the disease process and/or pulmonary microvascular damage.
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35.
  • Selmeryd, Jonas, et al. (författare)
  • Impact of left ventricular geometry on long-term survival in elderly men and women
  • 2014
  • Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 34:6, s. 442-448
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Adverse loading conditions and cardiac injury lead to remodelling of the heart into different patterns of left ventricular (LV) geometry. Geometry can be classified into LV hypertrophy (LVH), concentric remodelling (CR) or normal geometry (NG). The prognostic implications of the different geometric patterns have been extensively studied in middle-aged subjects, but data are scarcer for elderly populations. Methods: From a community-based random sample of 75-year-old men and women, subjects with normal LVEF were selected (n = 303). All-cause and cardiovascular mortality was analysed by LV geometry with Cox regression (unadjusted and adjusted for sex, prevalent hypertension, smoking, diabetes and prevalent ischaemic heart disease). Median follow-up time was 9.9 years. Results: Prevalence of CR and LVH was 19% and 17%, respectively. Hazard ratios (HRs) for CR were 0.93 (95% CI 0.54-1.58) for all-cause and 1.13 (0.48-2.65) for cardiovascular mortality. HRs for LVH were 2.01 (1.30-3.10) for all-cause and 3.55 (1.89-6.67) for cardiovascular mortality. As non-proportionality was present in the form of an increasing hazard for LVH, we partitioned the follow-up time at the median event time (approximately 7 years) and performed Cox regression separately within each time period. HRs for LVH during the first period were 1.23 (0.63-2.42) for all-cause and 1.79 (0.69-4.65) for cardiovascular mortality, while HRs for the second period were 3.06 (1.73-5.41) for all-cause and 6.60 (2.82-15.39) for cardiovascular mortality. Conclusion: In this community-based sample of 75-year-old men and women with normal LVEF, LVH was associated with an adverse prognosis during long-term follow-up, whereas CR was not.
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36.
  • Starck, Sven-Åke, et al. (författare)
  • Evaluation and optimization of administered activity, scanning parameters and hydration at 99m Tc hydroxymethylene diphosphonate adult whole-body bone imaging
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 32:6, s. 431-436
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To find out the method of optimal activity administration and scanning parameters to fulfil guidelines and diagnostic reference levels and to reach a maximal contrast-to-noise ratio (CNR) in bone imaging. We also investigate the influence on CNR and bladder activity in well-hydrated patients.Methods: A total of 225 patients were included. The first group of 101 patients was used to find out the optimal method to administer activity in terms of optimized CNR. The next two groups with 62 patients each were hydrated with 1500 ml water in two different time periods. CNR, bladder area and content were calculated.Results: An administrated activity per metre body height gave the highest CNR (5.43). A standard activity had the lowest percentage (2%) of images with <1.5 million counts. Early hydration decreased CNR from 5.41 to 4.85 (P = 0.06), with late hydration to 5.29 (NS). Studies with too few pulses were increased from 2 to 11% to a level of 15-26% and 11-21%, respectively. Early hydration reduced the bladder activity from 20.7 to 10.1 MBq (P<0.01), late hydration to 14.8 MBq (P = 0.08). The bladder size was enlarged from the no hydrated group (1406 mm2) to the early hydrated group (2406 mm2, P<0.000) and between the early and late hydrated group (3183 mm2, P<0.05).Conclusion: A standard activity in sufficient quantity is the most practical method, in addition to have the lowest percentage of images with too few pulses. A high fluid intake is not recommended because of problems with disturbing bladder content.
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37.
  • 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
  •  
38.
  • Sundström, Daniel, et al. (författare)
  • Acute effects on the ventricular function in Swedish snuffers : an echocardiographic study
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - Hoboken, USA : Wiley-Blackwell. - 1475-0961 .- 1475-097X. ; 32:2, s. 106-113
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: Cigarettes and Swedish snuff contain nicotine, which influence the cardiovascular system. Cigarette smoke has been shown to give an acute impairment in diastolic heart parameters. The systolic and diastolic heart function in snuff users is not thoroughly enough investigated. The aim of this study was to investigate if Swedish snuff will give an acute decrease in systolic and diastolic heart parameters in the left and right ventricles in healthy Swedish snuffers.Methods and results: Thirty healthy volunteers were examined with echocardiography. The study involved recordings from four different times: before snuff intake, 5 and 30 min after intake and finally 30 min after snuff withdrawal. The systolic and diastolic heart parameters were collected with conventional echocardiographic methods. In addition, the heart frequency and blood pressure response were measured. The pulse and blood pressure response were significantly altered (P<0Æ01) during the test. Left ventricular ejection fraction and the amplitudes of mitral and tricuspid annulus motion did not alter significantly. The main finding in the study was the significant decrease (P<0Æ05) in several diastolic heart parameters for both the left and right ventricles.Conclusions: This study shows that snuff intake causes a significant decrease in E ⁄ A ratio and a delay in ventricular relaxation and therefore a decrease in diastolic heart function in the left and right ventricles. The mechanism behind these alterations is probably very complex, but a combination of nicotine effects and loading conditions is probably the main factor.
  •  
39.
  • Sundström, Daniel, et al. (författare)
  • Chronic nicotine effects on left ventricular function in healthy middle-aged people : an echocardiographic study
  • 2013
  • Ingår i: Clinical Physiology and Functional Imaging. - : John Wiley & Sons. - 1475-0961 .- 1475-097X. ; 33:4, s. 317-324
  • Tidskriftsartikel (refereegranskat)abstract
    • AimsCigarettes and Swedish snuff influence the cardiovascular system in many ways. Cigarette and snuff usage have been linked with an acute impairment in several diastolic cardiac parameters during intake. The aim of this study is to investigate whether long-term usage of Swedish snuff or cigarettes also causes a more permanent impairment of systolic and/or diastolic cardiac parameters in the left ventricle in otherwise healthy middle-aged snuffers and smokers.Methods and resultsEighty-seven age-matched volunteers were included and examined with echocardiography. The volunteers were divided into three subgroups; one group with non-tobacco users, one group with long-term smokers and finally one group with long-term snuffers. The smokers and snuffers were instructed not to use these products for at least 5h before the examination. The systolic and diastolic cardiac parameters were collected at one time. Most of the systolic parameters measured were unaltered between the tobacco subgroups and non-tobacco users, and therefore, no alteration of significance was found in systolic parameters. Also, almost all of the diastolic parameters measured were not significantly impaired in the tobacco subgroups compared with non-tobacco users. However, the deceleration time (DT) was slightly prolonged (P<0 center dot 05) and thus statistically significant in the tobacco subgroups. This finding is somewhat difficult to interpret but may be seen as random.ConclusionsThis study reveals that most systolic- and diastolic cardiac parameters are not chronically significantly altered in middle-aged long-term tobacco users compared with age-matched non-tobacco users.
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40.
  • 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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41.
  • Vedung, Torbjörn, et al. (författare)
  • Intravenous adrenaline infusion causes vasoconstriction close to an intramuscular microdialysis catheter in humans.
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 30:6, s. 399-405
  • Tidskriftsartikel (refereegranskat)abstract
    • AIM: To test if a small muscle injury influences the vascular reactivity to adrenaline in human skeletal muscle. METHODS: Blood flow was measured by ¹³³Xenon clearance in the gastrocnemius muscle of eight male subjects at basal and during i.v. infusion of adrenaline (0.1 nmol kg⁻¹ min⁻¹) or placebo. Measurements were done with (expts 2 and 3) or without (expt 1) the influence of a small muscle injury induced by inserting a microdialysis catheter. ¹³³Xenon was administered either (expt 1) conventionally into the muscle via a fine needle, or (expts 2 and 3) through a fine tube close to the inserted microdialysis catheter. Expt 3 (control expt) was identical to expt 2 except that placebo was infused instead of adrenaline. Mean ± SEM, n= 8. RESULTS:   The blood flow tended to increase during the adrenaline infusion in expt 1 (1.17 ± 0.10 to 1.39 ± 0.15, N.S.), whereas it decreased during the adrenaline infusion in expt 2, from 1.39 ± 0.14 to 1.03 ± 0.14 ml min⁻¹ 100 g tissue⁻¹ (P<0.001). The blood flow change in response to adrenaline infusion was significantly different in expt 1 and expt 2 (P<0.05). Blood flow also decreased during the placebo infusion in expt 3 (1.15 ± 0.10 to 1.00 ± 0.09, P<0.01), but this decrease was significantly smaller than in response to the adrenaline infusion in expt 2, P<0.01. CONCLUSION: The present results are consistent with the hypothesis that the small muscle injury caused by the inserted microdialysis catheter influences the vascular reactivity to adrenaline in a vasoconstrictive direction.
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42.
  • Waldenström, Anders, et al. (författare)
  • Ischaemic preconditioning reduces myocardial calcium overload in coronary-occluded pig hearts shown by continuous in vivo assessment using microdialysis.
  • 2012
  • Ingår i: Clinical physiology and functional imaging. - Malden, MA : Wiley-Blackwell. - 1475-097X .- 1475-0961. ; 32:2, s. 133-8
  • Tidskriftsartikel (refereegranskat)abstract
    • During ischaemia, ATP depletion leads to insufficient fuelling for Na(+) /K(+) ATPase, decreased electrochemical potential and increased influx of calcium ions. This study demonstrated a means to assess the effects of ischaemic preconditioning (IP) on the free intracellular Ca(2+) pool during prolonged ischaemia. In a porcine myocardial ischaemia model, microdialysis (MD) was used for sampling of metabolic and injury markers in IP and non-IP (control) groups. (45) Ca(2+) was delivered in microperfusate locally to ischaemic myocardium, with distribution and uptake assessed by (45) Ca(2+) recovery in microdialysate. Cardiomyocytes in vitro were exposed to a Ca(2+) ionophore and tested for (45) Ca(2+) uptake. An accentuated myocardial calcium ion influx (observed as an increased microdialysate (45) Ca(2+) recovery in the extracellular milieu) was noted in control pigs compared with IP pigs during ischaemia. Suspended cardiomyocytes preincubated with a Ca(2+) ionophore to increase the intracellular calcium ion pool and subsequently incubated with (45) Ca(2+) , displayed lower (45) Ca(2+) uptake in cells compared with control cells not exposed to the ionophore, corroborating the idea of a strong relationship between degree of intracellular calcium overload and microdialysate (45) Ca(2+) recovery. The ischaemic insult was differentially verified by metabolic and injury markers. We introduce an in vivo method for serial assessment of myocardial calcium overload during ischaemia, using a MD technique and (45) Ca(2+) inclusion. IP leads to relatively less calcium overload as assessed by this new method, and we interpret this to mean that reduction in calcium overload is an important part of the IP protective effect.
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43.
  • Wester, T., et al. (författare)
  • Assessment of skin and tongue microcirculation reveals major changes in porcine sepsis
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - : Blackwell. - 1475-0961 .- 1475-097X. ; 31:2, s. 151-158
  • Tidskriftsartikel (refereegranskat)abstract
    • Aim:  To examine the relation between central hemodynamics, clinical severity and microvascular findings in tongue and skin during sepsis. Materials and methods:  Skin and tongue microcirculation was examined using laser Doppler and video microscopy techniques before and 200 min after inducing sepsis in pigs (n = 6) by inactivated Neisseria meningitides and in two control animals. Results:  All infected pigs developed clinical signs of sepsis. Pericapillary bleedings developed in the tongue in the two pigs with the most severe disease. Capillary density increased in the groin skin in infected pigs after 200 min as compared to baseline (P < 0·02). In the same period, mean capillary flow velocity was reduced in groin skin and tongue in septic pigs (P < 0·02). At 200 min a fraction of capillaries had developed 'no flow' or 'brisk flow', patterns hardly seen at baseline. Laser Doppler perfusion was reduced in ear and tongue after 200 min (P < 0·02 for both). The described pathology was more pronounced in the pigs with the most severe sepsis. Conclusion:  Capillary bleedings may be used as an early indication of severe sepsis. Examination of skin and tongue microcirculations may be used to characterize severity of sepsis and possibly to assess effect of treatment.
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44.
  • Yousry, M., et al. (författare)
  • Real-time imaging required for optimal echocardiographic assessment of aortic valve calcification
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961 .- 1475-097X. ; 32:6, s. 470-475
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction Aortic valve calcification (AVC), even without haemodynamic significance, may be prognostically import as an expression of generalized atherosclerosis, but techniques for echocardiographic assessment are essentially unexplored. Methods Two-dimensional (2D) echocardiographic recordings (Philips IE33) of the aortic valve in short-axis and long-axis views were performed in 185 consecutive patients within 1 week before surgery for aortic stenosis (n = 109, AS), aortic regurgitation (n = 61, AR), their combination (n = 8) or dilation of the ascending aorta (n = 7). The grey scale mean (GSMn) of the aortic valve in an end-diastolic short-axis still frame was measured. The same frame was scored visually 15 as indicating that the aortic valve was normal, thick, or had mild, moderate or severe calcification. The visual echodensity of each leaflet was determined real time applying the same 5-grade scoring system for each leaflet, and the average for the whole valve was calculated. Finally, a similar calcification score for the whole valve based on inspection and palpation by the surgeon was noted. Results Visual assessment of real-time images using the proposed scoring system showed better correlation with the surgical evaluation of the degree of valve calcification (r = 0.83, P<0.001) compared to evaluation of stop frames by visual assessment (r = 0.66, P<0.001) or the GSMn score (r = 0.64, P<0.001). High inter- and intra-observer correlations were observed for real-time visual score (both intraclass correlation coefficient = 0.93). Conclusion Real-time evaluation of the level of AVC is superior to using stop frames assessed either visually or by dedicated computer grey scale measurement software.
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45.
  • Zachrisson, Helene, et al. (författare)
  • Diameter and compliance of the greater saphenous vein - effect of age and nitroglycerine
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - : Blackwell Publishing Ltd. - 1475-0961 .- 1475-097X. ; 31:4, s. 300-306
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: The greater saphenous vein (GSV) is commonly used in autologous vein graft surgery. GSV diameter has proven to influence graft patency, and furthermore venous compliance might be of importance. The purpose of the study was to evaluate the effect of age on GSV diameter and compliance, and to evaluate the effect of nitroglycerine (NTG). Methods: The diameter and compliance of the GSV, with and without NTG, were examined with B-mode ultrasound in 12 elderly (70.3 +/- 1.2 year) and 15 young (25.1 +/- 0.6 year) men. The GSV diameter at the thigh and calf level was measured at rest, after 6 min of venous stasis (60 mmHg) and after NTG administration. Pressure-area curves during a linear venous pressure decrease were produced. Venous compliance was calculated using the quadratic regression equation (area) = beta(0) + beta(1) (cuff pressure) + beta(2) (cuff pressure)(2). Results: GVS diameter between the groups showed significant lower diameter in elderly compared to young men (Pless than0.05). Venous occlusion increased GSV diameter in elderly men (Pless than0.01) as well as young men (Pless than0.001). NTG increased GSV diameter in elderly men (Pless than0.01) with an equal trend in young men. During venous occlusion, after administration of NTG, GSV diameter increased further in both elderly (Pless than0.01) and young men (Pless than0.001). GSV compliance was decreased in elderly (beta(1), 0.037 +/- 0019, beta(2), -0.000064 +/- 00017) versus young men (beta(1), 0.128 +/- 0.013, beta(2), -0.00010 +/- 000018) [Pless than0.001 (beta(1)), Pless than0.02 (beta(2))]. Conclusions: Baseline GSV diameter as well as GSV compliance is decreased in elderly men compared to the young subjects. As reduced GSV diameter as well as reduced compliance is related to decreased graft patency, these findings might be of importance for the uses of GSV as graft material in cardiovascular bypass surgery. The clinical value has to be clarified in future studies.
  •  
46.
  • Zachrisson, Helene, et al. (författare)
  • Functional assessment of high-grade ICA stenosis with duplex ultrasound and transcranial Doppler.
  • 2012
  • Ingår i: Clinical physiology and functional imaging. - : Wiley-Blackwell. - 1475-097X .- 1475-0961. ; 32:3, s. 241-6
  • Tidskriftsartikel (refereegranskat)abstract
    • Duplex ultrasound (DUS) has shown a >90% accuracy compared to angiography, concerning the degree of internal carotid artery (ICA) stenosis. However, uncertainty may occur in a severe stenosis, in which peak systolic velocity (PSV) may decrease owing to high flow resistance or high backward pressure. We investigated intracranial collateral flows using transcranial Doppler (TCD) to further evaluate the hemodynamic significance of high-grade ICA stenosis.
  •  
47.
  • Gudmundsson, P, 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. - 1475-0961. ; 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((R)) 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((R)) infusion, before and throughout adenosine stress, also used for SPECT. Quantitative off-line analyses of myocardial perfusion by RTP-ASE Qontrast((R))-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((R))-generated images, especially by combined A, beta and Axbeta image interpretation. However, the technique needs improvements regarding the LCx and RCA territories.
  •  
48.
  • Bitzén, Ulrika, et al. (författare)
  • Measurement and mathematical modelling of elastic and resistive lung mechanical properties studied at sinusoidal expiratory flow.
  • 2010
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 30, s. 439-446
  • Tidskriftsartikel (refereegranskat)abstract
    • Summary Elastic pressure/volume (P(el)/V) and elastic pressure/resistance (P(el)/R) diagrams reflect parenchymal and bronchial properties, respectively. The objective was to develop a method for determination and mathematical characterization of P(el)/V and P(el)/R relationships, simultaneously studied at sinusoidal flow-modulated vital capacity expirations in a body plethysmograph. Analysis was carried out by iterative parameter estimation based on a composite mathematical model describing a three-segment P(el)/V curve and a hyperbolic P(el)/R curve. The hypothesis was tested that the sigmoid P(el)/V curve is non-symmetric. Thirty healthy subjects were studied. The hypothesis of a non-symmetric P(el)/V curve was verified. Its upper volume asymptote was nearly equal to total lung capacity (TLC), indicating lung stiffness increasing at high lung volume as the main factor limiting TLC at health. The asymptotic minimal resistance of the hyperbolic P(el)/R relationship reflected lung size. A detailed description of both P(el)/V and P(el)/R relationships was simultaneously derived from sinusoidal flow-modulated vital capacity expirations. The nature of the P(el)/V curve merits the use of a non-symmetric P(el)/V model.
  •  
49.
  • Dangardt, Frida, 1977, et al. (författare)
  • Reduced cardiac vagal activity in obese children and adolescents
  • 2011
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 31:2, s. 108-13
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: Obese children present with various cardiovascular risk factors affecting their future health. In adults, cardiac autonomic function is a major risk factor, predicting cardiovascular morbidity and mortality. We hypothesized that obese children and adolescents had a lower cardiac vagal activity than lean subjects. We measured cardiac spontaneous baroreflex sensitivity (BRS), reflecting the dynamic regulation of cardiac vagal function, in large groups of obese and lean young individuals. METHODS AND RESULTS: Cardiac BRS, using the sequence approach, was assessed in 120 obese (59 girls), 43 overweight (23 girls) and 148 lean subjects (78 girls). Obese subjects showed a decreased BRS compared to both overweight and lean subjects [16+/-7 versus 21+/-9 (P<0.01) and 22+/-10 ms per mmHg (P<0.0001), respectively]. The differences remained after correcting for age, gender and pubertal status. CONCLUSION: Children with obesity had low vagal activity at rest, and there was no gender difference.
  •  
50.
  • Frantz, Sophia, et al. (författare)
  • Atherosclerotic plaques in the internal carotid artery and associations with lung function assessed by different methods.
  • 2012
  • Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 32:2, s. 120-125
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Previous studies on associations between reduced lung function and cardiovascular disease (CVD) have mainly been based on forced expiratory volume in 1-s (FEV(1) ) and vital capacity (VC). This study examined potential associations between five different lung function variables and plaques in the internal carotid artery (ICA). Methods: Subjects (n = 450) from a previous population-based respiratory questionnaire survey [current smokers without lower respiratory symptoms, subjects with a self-reported diagnosis of chronic obstructive pulmonary disease (COPD) and never-smokers without lower respiratory symptoms] were examined using spirometry, body plethysmography and measurements of diffusing capacity for CO (D(L,CO) ). Plaques in the ICA were assessed by ultrasonography. Results: Two hundred and twenty subjects were current smokers, 139 ex-smokers and 89 never-smokers. COPD was diagnosed in 130 subjects (GOLD criteria). Plaques in the ICA were present in 231 subjects (52%). General linear analysis with adjustment for established risk factors for atherosclerosis, including C-reactive protein, showed that D(L,CO) was lower [77·4% versus 83·7% of predicted normal (PN), P = 0·014] and residual volume (RV) was higher (110·3% versus 104·8% of PN, P = 0·020) in subjects with than without plaques in the ICA. This analysis did not show any statistically significant association between plaques and FEV(1) or VC. Conclusion: The occurrence of plaques in the ICA was associated with low D(L,CO) and high RV, but not significantly with FEV(1) or COPD status. The results suggest that the relationships between reduced lung function, COPD and CVD are complex and not only linked to bronchial obstruction and low-grade systemic inflammation.
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