| 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.
|
|
| 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.
|
|
| 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.
|
|
| 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.
|
|
| 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.
|
|
| 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.
|
|
| 7. |
|
|
| 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.
|
|
| 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%).
|
|
| 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.
|
|
