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| 4. |
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| 5. |
- Andersson, Staffan, et al.
(författare)
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A laser Doppler technique for measuring distal blood-pressure : a comparison with conventional strain-gauge technique
- 1986
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Ingår i: Clinical Physiology. - 0144-5979 .- 1365-2281. ; 6:4, s. 329-335
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-five patients with peripheral circulatory disorders were examined by laser Doppler and strain-gauge techniques to compare these methods of measuring distal systolic blood-pressure. The correlation coefficients for simultaneous measurement of toe and ankle systolic blood-pressures were high, 0.98 and 0.99 respectively. The correlation coefficient for successive measurements of toe pressure was lower, 0.83, probably because of a variation in blood-pressure with time. The laser Doppler method seems to be more sensitive than the strain-gauge method in the low-pressure range. The laser Doppler probe is easy to attach to most skin surfaces and the laser Doppler technique may be, therefore, an alternative and a complement to the strain-gauge method when the strain-gauge is difficult to use on damaged or ulcerous toes and feet.
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| 6. |
- Andersson, Staffan, et al.
(författare)
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Continuous and stepwise cystometry through suprapubic catheters : effect of infusion pattern and infusion rate on the cystometrogram of the normal human bladder
- 1989
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Ingår i: Clinical Physiology. - 0144-5979 .- 1365-2281. ; 9:1, s. 89-96
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Tidskriftsartikel (refereegranskat)abstract
- Continuous cystometry at two filling rates (50 and 100 ml min-1) and stepwise cystometry (successive rapid volume infusions followed by bladder wall relaxation) were performed in 12 healthy subjects. Suprapubic catheters were used for infusion and recording of perivesical and intravesical pressures. The continuous cystometrograms obtained at filling rates of 50 and 100 ml min-1, respectively, did not differ with respect to desire to void, transmural pressure increase or bladder capacity. Stepwise cystometry allowed the bladders to be filled to a slightly larger volume than during continuous cystometry, but with comparatively lower transmural pressures only at very large distension of the bladder. There was considerable inter-individual variation in transmural pressure at both continuous and stepwise cystometry. Stepwise cystometry did not appear to provide any important additional information about pressure-volume relationship in the normal human bladder than could be obtained at routine clinical cystometry
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| 7. |
- Andren, Bertil, et al.
(författare)
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The influence of body composition on left ventricular mass and other echocardiographic and Doppler measurements in 70-year-old males
- 1995
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Ingår i: Clinical Physiology. - 0144-5979 .- 1365-2281. ; 15:5, s. 425-433
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Tidskriftsartikel (refereegranskat)abstract
- Heart morphology and function are often related to body size. The most common way to standardize for body composition is to divide these measures by body surface area (BSA). It has, however, been suggested that left ventricular mass (LV mass) ought to be indexed for height and that cardiac output is influenced by the body fat distribution.As part of a health screening programme of 70-year-old males in Uppsala, Sweden, 100 consecutive men were investigated with echocardiography and Doppler with regard to cardiac morphology and function. These measures were related to an evaluation of body composition using an X-ray method (dual energy X-ray absorptiometry).Lean body mass was strongly related to BSA and body weight (r=0.90 and 0.89, respectively; P<0.001), and to a lesser degree to height (r=0.70, P<0.0001). In the healthy part of the population (n=39), relationships between LV mass on the one hand and lean body mass, BSA and height on the other were seen (r=0.51, 0.51 and 0.50, respectively; P<0.01). Stroke volume calculated according to Teichholtz (but not when calculated with Doppler) showed a significant correlation to lean body mass (r=0.38, P<0.05). Also, left ventricular diameter and the thickness of the free wall were related to lean body mass (r=0.40 and 0.39, respectively; P<0.05). All of the evaluated relationships were generally weaker and in most cases no longer significant when evaluated in the part of the population with diseases known to affect the heart.No significant correlations were seen between the size of the left atrium, septal thickness or indices of diastolic function (E/A-ratio, isovolumic relaxation time, deceleration time) and the indices of body composition. No measures of cardiac morphology and function were significantly related to the amount of body fat or body bone.LV mass, stroke volume and left ventricular diameter were found to be correlated with lean body mass, but not with the amount of fat, in healthy 70-year-old males.
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| 8. |
- Appelberg, Jonas, 1964-, et al.
(författare)
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Ventilatory response to CO2 in patients with snoring, obstructive hypopnoea and obstructive apnoea
- 1997
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Ingår i: Clinical Physiology. - : Wiley-Blackwell Publishing Inc.. - 0144-5979 .- 1365-2281. ; 17:5, s. 497-507
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Tidskriftsartikel (refereegranskat)abstract
- Obstructive sleep apnoea (OSA) is caused by an obstruction of the upper airway. Sufficient sensitivity to CO2 in the respiratory centre is known to be a critical factor for adequate tone in the upper airway muscles. The hypothesis of this study is, therefore, that the ventilatory response to CO2 is reduced in patients with OSA. Twenty-six patients who suffered from snoring, 19 snoring patients with obstructive hypopnoea (OH) and 33 snoring patients with obstructive apnoea (OA), were studied. The control group consisted of 25 subjects from a random sample with no history of snoring or daytime sleepiness. Tests of the hyperoxic and hypoxic ventilatory response to CO2 were performed, as well as static and dynamic spirometry. Subjects in the OA group displayed a higher hyperoxic (VE/FetCO2hy = 12.6 l min-1/%) and hypoxic (VE/FetCO2ho = 15.7 l min-1/%) ventilatory response to CO2 than patients with obstructive hypopnoea (VE/FetCO2hy = 8.6 l min-1/%; VE/FetCO2ho = 15.2 l min-1/%), snorers (VE/FetCO2hy = 8.4 l min-1/%; VE/FetCO2ho = 12.7 l min-1/%) and non-snorers (VE/FetCO2hy = 7.6 l min-1/%; VE/FetCOho = 9.6 l min-1/%). Multiple regression analysis reveals that neck circumference, apnoea index, oxygen desaturation index, PCO2 and sex (male gender) are correlated with VE/FetCO2hy (R2 = 0.43). Multiple regression analysis also reveals that ERV (expiratory reserve volume) and sex (male gender) are correlated with VE/FetCO2ho (R2 = 0.21). Arguing against the hypothesis, patients with OSA displayed an increased hyperoxic and hypoxic ventilatory response to CO2. Nocturnal apnoea frequency and the obesity factor in OSA may have contributed to these results.
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| 9. |
- Baer, R, et al.
(författare)
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Effects of triglycyl-lysine-vasopressin on cardiovascular responses to orthostatic stress.
- 1987
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Ingår i: Clinical Physiology. - 0144-5979 .- 1365-2281. ; 7:4, s. 329-35
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Tidskriftsartikel (refereegranskat)abstract
- The influence of triglycyl-lysine-vasopressin (TGLVP) on cardiovascular responses to orthostatic stress was studied. Arterial pressures, heart rate (HR) and stroke volume (SV) were measured in eight healthy males subjected to 20 min 70 degrees head-up tilt. On different days they received either 0.01 mg/kg b.w. of TGLVP or a corresponding volume of 0.9% saline i.v. after 15 min supine rest. After the drug injection, in supine subjects, HR had decreased from 58 to 50 beats min-1, total peripheral resistance (TPR) was elevated by 29%, systolic (SAP) and diastolic pressure (DAP) had increased by 7 and 8 mmHg, respectively. During tilt, values for HR and SAP were similar with and without TGLVP whereas DAP and MAP were elevated 8 and 7 mmHg, respectively, by the drug. 4-8 min into the tilt, TGLVP caused an 8% sustained curtailment of SV. Both with and without the drug TPR increased by about 30% in response to head-up tilt. Thus, the marked peripheral arteriolar constriction after vasopressin in the supine position was not affected by head-up tilt. Tilting also abolished the drug-induced elevation in SAP, most likely explained by the reduction in SV. Although TPR was markedly increased by TGLVP during head-up tilt, reflected in the behaviour of DAP, the response of SV speaks against any beneficial effect of this drug on orthostatic tolerance in healthy subjects.
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| 10. |
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| 11. |
- Bennhagen, Rolf, et al.
(författare)
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High-frequency components in ECG analysed in guinea-pig Langendorf preparations
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 21:5, s. 576-583
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Tidskriftsartikel (refereegranskat)abstract
- High-frequency components in ECG during global ischaemia were studied in isolated guinea-pig hearts perfused ad modum Langendorf. Electrocardiograph recordings were carried out from the epicardial surface both in normo- and low-flow perfusion. After bandpass filtering (5-500 Hz), signal-averaging, was undertaken. The high-frequency components either increased or decreased after low-flow perfusion was instituted. Root-mean-square voltage (RMS) of the depolarization signal correlated poorly with the signal amplitude, but highly with the first and second derivative, i.e. the velocity and the acceleration of the signal. It is concluded that high-frequency components are not pathological phenomena per se, but reflect the shape of the original electrocardiographic signal.
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| 12. |
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| 13. |
- Berg, J, et al.
(författare)
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CAVIAR : a tool to improve serial analysis of the 12-lead electrocardiogram
- 1995
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 0144-5979. ; 15:5, s. 435-445
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Tidskriftsartikel (refereegranskat)abstract
- An important part of an electrocardiogram (ECG) interpretation is the comparison between the present ECG and earlier recordings. The purpose of the present study was to evaluate a combination of two computer-based methods, synthesized vectorcardiogram (VCG) and CAVIAR, in this comparison. The methods were applied to a group of 38 normal subjects and to a group of 36 patients treated with anthracyclines. A fraction of these patients are likely to develop cardiac injury during or after the treatment, since anthracyclines are known to cause heart failure and cardiomyopathy. Two ECGs were recorded on each patient, one before and one after the treatment. On each normal subject, two ECGs were recorded with an interval of 8-9 years. A synthesized VCG was calculated from each ECG and the two synthesized VCGs from each subject were analysed with the CAVIAR method. The CAVIAR analysis is a quantitative method and normal limits for four measurements were established using the normal group. Values above these limits were more frequent in the patient group than in the normal group. The conventional ECGs were also analysed visually by an experience ECG interpreter without knowledge of the result of the CAVIAR analysis. No significant serial changes were found in 10 of the patients with high CAVIAR values. Changes in the ECGs were found in two patients with normal CAVIAR values. In summary, synthesized VCG and CAVIAR could be used to highlight small serial changes that are difficult to find in a visual analysis of ECGs.
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| 14. |
- Blomstrand, Peter, et al.
(författare)
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Assessment of left ventricular diastolic function from mitral annulus motion, a comparison with pulsed Doppler measurements in patients with heart failure
- 1996
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Ingår i: Clinical Physiology. - : John Wiley & Sons. - 0144-5979 .- 1365-2281. ; 16:5, s. 483-493
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Tidskriftsartikel (refereegranskat)abstract
- Mitral and pulmonary venous flow velocity recordings are often used for the assessment of left ventricular diastolic function. These curves are, however, also influenced by other factors. To investigate whether mitral annulus motion carries additional information in this context, mitral annulus motion was compared to Doppler registrations of mitral and pulmonary flow velocities in 38 patients with heart failure (NYHA II-III) after myocardial infarction. Patients with an increased atrial contribution to mitral annulus motion (> 57%, n = 12) had a higher mitral late-to-early flow velocity ratio (A/E) and pulmonary systolic to diastolic filling ratio (< 0.01). Patients with atrial displacement above average for the group (≤ 5.1 mm, n = 19) had a higher mitral A/E ratio and pulmonary systolic to diastolic filling ratio than patients with a lower than average atrial component (P < 0.05). There was a significant correlation between a/T ratio and A/E ratio (r = 0.61, P < 0.001) and between pulmonary flow and transmitral flow (= 0.76, P < 0.001). We conclude that an increased atrial displacement of the mitral annulus is a frequent finding in patients with signs of left ventricular relaxation abnormality. There is a significant correlation between a/T ratio and A/E ratio but the information contained in the two indices are not identical.
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| 15. |
- Blomstrand, Peter, et al.
(författare)
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Exercise echocardiography : a methodological study comparing peak‐exercise and post‐exercise image information
- 1992
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Ingår i: Clinical Physiology. - : John Wiley & Sons. - 0144-5979 .- 1365-2281. ; 12:5, s. 553-565
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Tidskriftsartikel (refereegranskat)abstract
- It is unclear whether echocardiography at peak bicycle exercise adds information to registrations obtained recumbent immediately after the test and what factors influence image quality. Therefore, exercise echocardiography was performed consecutively and prospectively in 66 men, unselected with regard to echocardiography, one month after an episode of unstable coronary artery disease. Of 594 segments (9 × 66), 569 (96%) were adequately visualized recumbent at rest. The corresponding figures recumbent directly after exercise, seated before exercise, and seated at peak exercise were 544 (92%), 474 (80%), and 428 (72%), respectively. In the majority of our patients, acceptable images at peak exercise were obtained for the septal region, while for the anterior, lateral, and inferior segments the success rate varied from 50 to 70%. Recumbent after exercise, the success rate was acceptable for most segments, possibly with the exception of the apical and lateral segments. Fifty‐five patients developed new wall motion abnormalities or worsening of wall motion in connection with exercise. Echocardiography at peak exercise provided more information than afterwards in patients with images of good quality. However, in patients with inferior image quality, the registrations obtained recumbent after the test revealed wall motion abnormalities which were not obtained seated at peak exercise. Patients with worse image quality had significantly higher respiratory rate and weight, and rated a higher degree of dyspnoea at peak exercise than those with good quality. We conclude that in middle aged men with coronary artery disease, image acquisition at peak bicycle exercise and immediately after exercise are of complementary value.
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| 16. |
- Blomström-Lundqvist, C
(författare)
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Late potentials--a clinical update
- 1992
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Ingår i: Clinical Physiology. - 0144-5979 .- 1365-2281. ; 12:3, s. 319-323
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Tidskriftsartikel (refereegranskat)
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| 17. |
- Bornmyr, S, et al.
(författare)
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Effect of local cold provocation on systolic blood pressure and skin blood flow in the finger
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 21:5, s. 570-575
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Tidskriftsartikel (refereegranskat)abstract
- Demonstration of increased vascular cold reactivity in patients with Raynaud's syndrome is difficult. For medico-legal reasons, it is important to get objective measures of vasospasm in these patients. Evaluation of the degree of vasospasm also provides prognostic information which is useful for patient management. In this study, we compare two methods of arterial circulation measurement. The laser Doppler scanning is a new method, which uses the recently developed laser Doppler perfusion imaging (LDPI) instrument. The aim of the present study was to compare the effect on finger skin blood flow measured with LDPI with changes in finger systolic blood pressure during local cold provocation. The effect of such provocation, skin blood flow and systolic blood pressure, were studied in 15 healthy controls. Six patients with known traumatic vasospastic disease (TVD) were also tested with both methods. Finger skin blood flow was measured with LDPI on the distal phalanx of the index finger of the left hand, every minutes during 6 min of local heating at 40 degrees C followed by local cooling for 3 min at 15 degrees C and then for 3 min at 10 degrees C. Finger systolic blood pressure was measured with strain-gauge method before and after local cooling to 10 degrees C with a cuff perfused with water of desired temperature. The test was performed in the same finger within a week of the laser Doppler scanning. Local finger cooling to 15 degrees C and 10 degrees C caused a significant decrease in blood flow, most marked at 10 degrees C. There was, however, no correlation between the decrease in blood flow and blood pressure. In the TVD-patients decreases in skin blood flow were similar compared with the healthy controls. In contrast, the changes in systolic blood pressure, were outside normal range (systolic quotient <0.65) in five of the six patients (83%), and also in 11 of the 15 healthy controls (73%). In conclusion, there is no correlation between the decrease in finger skin blood flow and systolic blood pressure during local cold provocation. For diagnosis of traumatic vasospastic disease (TVD), local cold-induced changes in finger systolic blood pressure seems superior to changes in skin blood flow, but the ideal clinical method for demonstrating increased cold-induced vasospasm is, however, still lacking.
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| 20. |
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| 21. |
- Brodszki, Jana, et al.
(författare)
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Reproducibility of ultrasonic fetal volume blood flow measurements
- 1998
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 18:5, s. 479-485
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Tidskriftsartikel (refereegranskat)abstract
- The intraobserver reproducibility of ultrasonic volume blood flow measurements in the human fetus was evaluated in this study. A new approach, simultaneous measurement of the vessel diameter and the flow velocity with a pulsed-wave Doppler ultrasound synchronized with a real-time ultrasound phase-locked echo-tracking system, was used to estimate volume blood flow (VBF) in the fetal descending aorta. Measurements were performed in a longitudinal study on 20 normally grown fetuses. Intraobserver reproducibility of repeated estimations of mean blood flow velocities throughout gestation was very good, with high values of intraclass correlation coefficient (IntraCC 0.80-0.91) and low values of coefficient of variation (CV 4-11%). The IntraCC of repeated vessel diameter measurements throughout gestation was low (0.30-0.68), whereas the values of CV were acceptable (< 12%), with the exception of the period between 140 and 167 gestational days (CV > 12%). The lower reproducibility of vessel diameter measurement contributed directly to the relatively low reproducibility of VBF estimations overall (IntraCC 0.25-0.70; CV 17-28%), as these are calculated from a formula using both flow velocity and vessel diameter. Nevertheless, the synchronized approach gives absolute values of vessel diameter, flow velocity and VBF comparable with values reported in the human fetus previously. The new method provides, by taking the vessel wall pulsations into consideration and by measuring diameter and velocity simultaneously, a more complete information on fetal haemodynamics and fetal physiology.
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| 22. |
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| 23. |
- Carlhäll, Carljohan, 1973-, et al.
(författare)
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Atrioventricular plane displacement correlates closely to circulatory dimensions but not to ejection fraction in normal young subjects
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 21:5, s. 621-628
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Tidskriftsartikel (refereegranskat)abstract
- Aims Mitral atrioventricular plane displacement (AVPD) provides information about left ventricular systolic function. M-mode of systolic annulus amplitude or tissue Doppler imaging of systolic annulus velocity are the current methods of evaluating AVPD. A correlation to ejection fraction (EF) has been demonstrated in patients with coronary artery disease and left ventricular dysfunction. Our aim was (i) to investigate the mitral AVPD of normal subjects with different physical work capacities and (ii) to further evaluate AVPD as an index of left ventricular systolic function.Methods and results Twenty-eight healthy men mean age 28 years (20–39) were included: endurance trained (ET) (n=10), strength trained (ST) (n=9) and untrained (UT) (n=9). The systolic AVPD was recorded at four sites, septal, lateral, anterior and posterior, using M-mode. Left ventricular volumes were calculated according to Simpson’s rule. Systolic AVPD was higher in endurance trained, 16·9 ± 1·5 mm, as compared with both strength trained, 13 ± 1·6 (P<0·001) and untrained, 14 ± 1·6 (P<0·001). Left ventricular systolic AVPD correlated strongly with end-diastolic volume (r=0·82), stroke volume (r=0·80) and maximal oxygen consumption per body weight (r=0·72). The correlation between AVPD and EF was poor (r=0·22).Conclusion In the subjects studied, with a range of normal cardiac dimensions, AVPD correlated to stroke volume, end-diastolic volume and maximal oxygen consumption per body weight, but not to EF. On theoretical grounds, it also seems reasonable that a dimension like AVPD is related to other cardiac dimensions and volumes, rather than to a fraction, like EF. AVPD is one parameter that is useful for evaluation of left ventricular systolic function but is not interchangeable with other measurements such as EF.
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| 24. |
- Carlsson, U, et al.
(författare)
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Plantar flexor muscle function in open and closed chain.
- 2001
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Ingår i: Clinical physiology (Oxford, England). - 0144-5979. ; 21:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, the torque or work produced during isometric, pure concentric and eccentric-concentric plantar flexions, performed in sitting, standing and prone were measured. The electromyographic (EMG) activity was measured from the soleus, gastrocnemius medialis, tibialis anterior and rectus femoris muscles. The isometric tests showed the highest torques in the standing test. The rectus femoris and gastrocnemius activities were lower in the prone than in the standing test. The sitting test showed lower activities in all muscles of the lower leg compared with the standing test. No differences in work between the prone and sitting tests were found during the concentric phases. Higher rectus femoris activity in the eccentric-concentric test and lower activity in the triceps surae during the concentric phases were seen in the sitting compared with the prone test. We conclude that tests of overall functional ability should be performed in the standing position while specific tests of the plantar flexors should be performed in the prone position.
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| 25. |
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| 26. |
- Damm, S., et al.
(författare)
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Wall motion abnormalities in male elite orienteers are aggravated by exercise
- 1999
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 19:2, s. 121-126
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Tidskriftsartikel (refereegranskat)abstract
- During the period 1979-92, 16 (15 men and one woman) sudden unexpected cardiac deaths occurred among young Swedish orienteers. This finding indicated a sharp increase in the death rate of orienteers, and necropsy demonstrated that myocarditis was a common histopathological finding. Therefore, an extensive non-invasive cardiac investigation was performed. A total of 59 male élite orienteers (mean age 23 years) and 36 cross-country skiers and middle-distance runners (mean age 22 years), serving as controls, were examined by both echocardiography at rest and radionuclide ventriculography at rest and during exercise. Wall motion abnormalities were found in eight orienteers using echocardiography. The purpose of this study was to examine whether the group of orienteers with wall motion abnormalities found using echocardiography had a smaller increase in ejection fraction from rest to exercise using radionuclide ventriculography than the rest of the orienteers and the controls, indicating an aggravation of the wall motion abnormalities during exercise. There were no significant differences in the ejection fraction at rest between the groups. In the orienteers with wall motion abnormalities (group 1), 62% (five out of eight) had less than a 0.05 unit increase in left ventricular ejection fraction compared with 27% (14 out of 51) of the remaining orienteers (group 2) and 19% (7 out of 36) of the controls (group 3). A comparison of athletes in group 1 with those in groups 2 and 3 combined revealed a statistically significant difference (P < 0.05). The divergent response in left ventricular ejection fraction during exercise suggests an aggravation of the wall motion abnormalities with exercise. Both the echocardiographic and the radionuclide ventriculographic findings indicate that the orienteers in group 1 had concealed left ventricular damage.
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| 27. |
- Eckert, Bodil, et al.
(författare)
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Hypoglycaemia leads to an increased QT interval in normal men
- 1998
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 18:6, s. 570-575
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Tidskriftsartikel (refereegranskat)abstract
- Hypoglycaemia is presumed to be the cause of death in about 3% of insulin-treated diabetic patients. Some of these patients suffer from hypoglycaemic brain damage, but the majority have no evident brain damage and are supposed to have died from other causes such as a cardiac arrhythmia. The putative mechanism is a hypoglycaemia-induced prolongation of the QT interval which increases the risk of malignant ventricular tachycardia. The aim of the present study was to examine the electrocardiogram during and after hypoglycaemia in healthy men. To that end, hypoglycaemia was induced by an intravenous infusion of insulin (2.5 mU kg-1 min-1) in 10 healthy men to reach a venous blood glucose level of 2.1 +/- 0.3 mmol l-1 for 65 +/- 9 min. Before hypoglycaemia, after 20 and 50 min of hypoglycaemia and 20 and 45 min after normalization of the blood glucose, the QT interval was measured by a ruler and corrected for the heart rate. Results are given as mean +/- SD and comparisons were made with an ANOVA, except for symptom scores and plasma adrenaline where non-parametric tests were used. When this indicated significance, further analysis was performed with a two-tailed t-test. During hypoglycaemia the corrected QT interval increased from 380 +/- 20 ms1/2 to 440 +/- 30 ms1/2 (P < 0.001), and the amplitude of the T wave decreased (P = 0.002). The serum potassium level decreased from 4.3 +/- 0.3 mmol l-1 to 3.5 +/- 0.2 mmol l-1 (P < 0.001) and the plasma adrenaline concentration increased from 0.20 +/- 0.04 nmol l-1 to 2.46 +/- 2.58 nmol l-1 (P < 0.01). The results of this study confirm that a prolongation of the QT interval occurs during hypoglycaemia, but the significance of this finding still has to be proven.
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| 28. |
- Edenbrand, L., et al.
(författare)
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Vectorcardiogram more sensitive than 12‐lead ECG in the detection of inferior myocardial infarction
- 1990
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Ingår i: Clinical Physiology. - 0144-5979. ; 10:6, s. 551-559
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Tidskriftsartikel (refereegranskat)abstract
- Summary. The vectorcardiogram (VCG) is commonly stated to be more sensitive than the 12‐lead electrocardiogram (ECG) for the diagnosis of inferior myocardial infarction. However, a recent study indicated that VCG is not superior to ECG for this diagnosis. The purpose of this study was to compare the performance of VCG and ECG criteria and to indicate possible explanations for the disagreement between earlier studies. Accordingly, we studied 65 patients with inferior myocardial infarction verified by left ventriculography or 201‐TI myocardial scintigraphy and 351 normal subjects. Sensitivity was 69% (45/65) and 43% (28/65) for the VCG and ECG criteria, respectively. This difference was highly significant (P<0·001). Among the normal subjects there were only three with false positive VCG and none with false positive ECG. We conclude that both VCG and ECG criteria for the diagnosis of inferior myocardial infarction are highly specific and that VCG criteria have greater sensitivity than ECG criteria.
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| 29. |
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| 30. |
- Eiken, Ola, et al.
(författare)
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Effects of ischaemic training on force development and fibre-type composition in human skeletal muscle
- 1991
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Ingår i: Clinical Physiology. - 0144-5979 .- 1365-2281. ; 11:1, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- Force (peak torque) of m. quadriceps femoris was measured during 60 repeated, voluntary dynamic knee extensions in 10 men before and after a 4-week training regimen of one-legged cycle exercise. Biopsies for histochemical analysis were obtained from the lateral vastus muscle after the training period. One leg was trained with the blood flow to the leg muscles reduced by local supra-atmospheric external pressure of 50 mmHg ('Ischaemic leg, I-leg'). Employing the same work-load profile the other leg was trained at normal atmospheric pressure ('Non-restricted-flow leg, N-leg'). In response to I-training, Maximum Peak Torqued (MPT; the highest torque produced in any contraction) and Initial Peak Torque (IPT; the average peak torque of the initial 12 contractions) decreased by 8% (P less than 0.01) and 9% (P less than 0.001), respectively. Final Peak Torque (FPT; the average peak torque of the final 12 contractions) increased by 13% (P less than 0.05) after I-training. No changes in MPT, IPT or FPT occurred following N-training. After training the proportion of slow-twitch fibres was higher (P less than 0.05) and the mean slow-twitch fibre area was larger (P less than 0.05) in the I-than in the N-trained leg. The results indicate that blood flow-restricted training, in contrast to non-restricted-flow training, decreases maximum voluntary dynamic force, possibly by inducing an increase in the share of the muscle cross-sectional area consisting of slow-twitch fibres. That flow-restricted training improves maintenance of force during short-term local exercise may reflect ischaemically induced changes in the metabolic characteristics of skeletal muscle.
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| 31. |
- Emilsson, Kent, 1963-, et al.
(författare)
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The mode of left ventricular pumping : is there an outer contour change in addition to the atrioventricular plane displacement?
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 21:4, s. 437-446
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Tidskriftsartikel (refereegranskat)abstract
- The outer contour of the heart has in some studies been shown to be constant during the heart cycle and the epicardial apex almost stationary whilst the base of the ventricles moves towards apex during systole. The base of the left ventricle has been regarded as a cylinder with constant cross-sectional area with changes in height during the heart cycle, the latter corresponding to the amplitude of mitral annulus motion (MAM). In this echocardiographic study, including 20 healthy adults, the stroke volume calculated by the cylinder model was significantly lower than by a reference method (modified Simpson's rule). MAM explained 82% of the stroke volume and 18% must, therefore, be explained by an inward motion of the outer left ventricular wall. A mean outer diameter shortening of about 3% (about 2 mm) was calculated.
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| 32. |
- Emilsson, Kent, 1963-, et al.
(författare)
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The relation between ejection fraction and mitral annulus motion before and after direct-current electrical cardioversion.
- 2000
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 20:3, s. 218-24
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Tidskriftsartikel (refereegranskat)abstract
- Mitral annulus motion (MAM) and the relation between left ventricular ejection fraction (EF) and MAM has been shown to differ between patients with sinus rhythm and patients with atrial fibrillation. However, it has not been investigated how the relation between EF and MAM changes on direct-current (DC) electrical cardioversion to sinus rhythm. Therefore, 31 consecutive patients on the waiting list for DC electrical cardioversion were examined by echocardiography before DC electrical cardioversion, and those who maintained sinus rhythm (13 patients) were examined again 4-8 weeks after cardioversion. The conversion factor (CF) (ratio EF/MAM) decreased from 8.4 +/- 1.7 before to 5.8 +/- 0.8 SD after cardioversion (P<0.001). The EF increased slightly (P<0.05) but the MAM had a much greater increase (P<0.001), resulting in the decrease in CF. There was no significant difference in CF between patients after cardioversion and age- and gender-matched control patients with sinus rhythm, indicating that CF is normalized or almost normalized 4-8 weeks after cardioversion. This indicates that when MAM is used for investigation of the left ventricular function, and the function is expressed as EF, the same CF as in other patients with sinus rhythm can be used 4-8 weeks after DC electrical cardioversion.
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| 33. |
- Emilsson, Kent, 1963-, et al.
(författare)
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The relation between mitral annulus motion and ejection fraction changes with age and heart size.
- 2000
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Ingår i: Clinical Physiology. - : John Wiley & Sons. - 0144-5979 .- 1365-2281. ; 20:1, s. 38-43
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Tidskriftsartikel (refereegranskat)abstract
- Mitral annulus motion (MAM) has recently been introduced as an index of left ventricular function. Several echocardiographic studies have shown good agreement between ejection fraction (EF) and MAM x 5, where MAM is the total mitral annulus motion, measured in mm, and EF is expressed as a percentage. This means that if MAM is used for estimation of left ventricular function, the conversion factor 5 is used, if the function is expressed as EF. In these studies, the mean age of the patients was over 60 years. The present study, including 102 patients, shows that in patients aged 20-40 years, the conversion factor is about 4.3, in patients aged 41-60 years it is about 4.6 and in patients aged 61-80 years it is about 5.0. It was also found that the ratio EF/MAM decreases with increasing height and left ventricular diameter, both variables closely connected to heart size. The results suggest that when MAM is used in assessment of left ventricular function, it is unwise to express the function in terms of EF. It is preferable to use MAM as a direct index of ventricular function, using reference values referred to aged and height. If the estimated function is expressed in terms of EF, different converting factors must be used depending on the age of the patients.
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| 34. |
- Emilsson, Kent, 1963-, et al.
(författare)
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The relation between mitral annulus motion and left ventricular ejection fraction in atrial fibrillation.
- 2000
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 20:1, s. 44-9
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Tidskriftsartikel (refereegranskat)abstract
- Mitral annulus motion (MAM) has recently been introduced as an index of left ventricular function. Previous studies have shown a good agreement between MAM (mm) x 5 and ejection fraction in middle-aged and elderly patients. These studies only included patients with sinus rhythm, while patients with atrial fibrillation were excluded. In the present study, MAM was reduced in patients with atrial fibrillation while ejection fraction (EF) did not differ from age-matched control patients with sinus rhythm. The 'conversion factor' (EF/MAM) was 7.2 in the group with atrial fibrillation and 5. 1 in controls with sinus rhythm. This difference must be taken into account when MAM is used to estimate left ventricular function in patients with atrial fibrillation. Patients with atrial fibrillation had lower stroke volume and higher heart rate than patients with sinus rhythm. A decreased systolic long-axis shortening was found (P<0.005) compared to patients with sinus rhythm, but no difference in short-axis diameter shortening.
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| 35. |
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| 36. |
- Holmlund, F, et al.
(författare)
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Sympathetic skin vasoconstriction--further evaluation using laser Doppler techniques
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 1365-2281 .- 0144-5979. ; 21:3, s. 287-291
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to quantify the reflex sympathetic vasoconstriction in skin at different depths. Twenty healthy subjects were studied. Finger skin blood flow was measured using laser Doppler perfusion imaging (LDPI) and laser Doppler perfusion monitoring (LDPM). In LDPM, a probe with fibres separated 0.25 mm (deep) and 0.14 mm (superficial) from the illuminating fibre was used. Local heating (40 degrees C) was achieved with a Peltier element, and reflex vasoconstriction induced by immersion of the contra-lateral hand and forearm for 3 min in water at 15 degrees C. The change in skin blood flow was measured and a vasoconstriction index (VAC: cooling/before cooling) calculated. VAC indices of LDPI, LDPM-0.25 and LDPM-0.14 were 0.60, 0.59 and 0.60, respectively. The two components of the LDPM perfusion value, blood cell velocity and concentration, were studied separately. Their contributions in LDPM-0.25 were roughly the same, whereas the velocity component dominated in LDPM-0.14, although their relative responses in the two channels were similar. We conclude that sympathetic skin vasoconstriction does not significantly differ in two compartments, as probed with fibres separated by 0.25 and 0.14 mm. Blood cell velocity is influenced in a proportional way, as is concentration.
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| 37. |
- Holst, Holger, et al.
(författare)
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A confident decision support system for interpreting electrocardiograms
- 1999
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979. ; 19:5, s. 410-418
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Tidskriftsartikel (refereegranskat)abstract
- Computer-aided interpretation of electrocardiograms (ECGs) is widespread but many physicians hesitate to rely on the computer, because the advice is presented without information about the confidence of the advice. The purpose of this work was to develop a method to validate the advice of a computer by estimating the error of an artificial neural network output. A total of 1249 ECGs, recorded with computerized electrocardiographs, on patients who had undergone diagnostic cardiac catheterization were studied. The material consisted of two groups, 414 patients with and 835 without anterior myocardial infarction. The material was randomly divided into three data sets. The first set was used to train an artificial neural network for the diagnosis of anterior infarction. The second data set was used to calculate the error of the network outputs. The last data set was used to test the network performance and to estimate the error of the network outputs. The performance of the neural network, measured as the area under the receiver operating characteristic (ROC) curve, was 0.887 (0.845-0.922). The 25% test ECGs with the lowest error estimates had an area under the ROC curve as high as 0.995 (0.982-1.000), i.e. almost all of these ECGs were correctly classified. Neural networks can therefore be trained to diagnose myocardial infarction and to signal when the advice is given with great confidence or when it should be considered more carefully. This method increases the possibility that artificial neural networks will be accepted as reliable decision support systems in clinical practice.
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| 38. |
- Holst, H., et al.
(författare)
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Intelligent computer reporting 'lack of experience' : A confidence measure for decision support systems
- 1998
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979. ; 18:2, s. 139-147
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to explore the feasibility of developing artificial neural networks that are able to provide confidence measures for their diagnostic advice. Computer-aided decision making can improve physician performance, but many physicians hesitate to use these 'black boxes'. If we are to rely upon decision support systems for such tasks as medical diagnosis it is essential that the computers indicate when the advice given is based on experience, i.e. give a confidence measure. An artificial neural network was trained to diagnose healed anterior myocardial infarction and to indicate 'lack of experience' when test electrocardiograms were different from the electrocardiograms of the training set. A database of 1249 electrocardiograms from patients who had undergone cardiac catheterization was used to train and test the neural network. Thereafter, the ability of the network to indicate 'lack of experience' was assessed using 100 left bundle branch block electrocardiograms, an electrocardiographic pattern that was excluded from the training set. The network indicated that 83% of the left bundle branch block electrocardiograms and 1% of the test electrocardiograms from catheterized patients were different from the electrocardiograms of the training set. All but one of the left bundle branch block electrocardiograms would otherwise be falsely classified as anterior myocardial infarction by the network. Artificial neural networks can be trained to indicate 'lack of experience', and this ability increases the possibility for neural networks to be accepted as reliable decision support systems in clinical practice.
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Janerot-Sjöberg, Birgitta, et al.
(författare)
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Quantitative digital evaluation of myocardial exercise thallium-201 single-photon emission tomography in post-menopausal women
- 1998
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 18:3, s. 169-177
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative computerized analysis of data from myocardial thallium-201 (201Tl) single-photon emission tomography (SPET) may improve the diagnostic accuracy of coronary heart disease. The reference ranges for post-menopausal women are, however, limited and obtained mainly from patients. To compare reference values from healthy post-menopausal women and to improve the quantitative analysis, 20 women (10 patients with coronary heart disease and previous infarction and 10 age-matched healthy volunteers) were examined immediately post exercise and after a delay. A nine-segment 'bull's-eye' model was used for analysis. At visual evaluation, reproducibility was high (93%), no false-positive results were obtained and in 70% of the patients the SPET was interpreted as abnormal. Using reported reference values for quantitative analysis, all the healthy women had an abnormal result. New reference values based on three different methods of 'normalization' were calculated: the relative activity of segment 3 set to 100%, the segment with the highest activity set to 100% and a least-squares method. They all differed significantly from those that had previously been reported. The frequencies of agreement between visual and quantitative analysis were 84-92% and were highest when segment 3 was used as a reference, but in this case only 40% of the patients with coronary heart disease had an abnormal SPET. Using the least-squares method for handling digital information, the SD of the normal values decreased and 90% of the patients with coronary heart disease were accurately diagnosed. These results provide quantitative digital reference values for healthy post-menopausal women. They verify that quantitative analysis is in diagnostic agreement with visual evaluation, stress the need for local verification of reference ranges and suggest a least-square normalization method for the analysis.
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| 43. |
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| 44. |
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| 45. |
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| 46. |
- Jonason, T., et al.
(författare)
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Menopause is associated with the stiffness of the common carotid artery in 50-year-old women
- 1998
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 18:2, s. 149-155
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Tidskriftsartikel (refereegranskat)abstract
- To determine if menopause has an effect on the elasticity of the arteries, the stiffness index of the common carotid artery was studied in 84 premenopausal and 139 post-menopausal women. The study group was age-homogeneous, all women being 50 years of age. There were no significant differences between pre- and post-menopausal women regarding atherosclerosis, when measured as the number of subjects with plaques or intimal-medial thickness. The diameter of the common carotid artery was significantly larger in post-menopausal women. The diameter was correlated to measurements of body size which did not, however, differ between the two groups. The mean stiffness indexes were 4.99 +/- 1.02 and 5.38 +/- 1.21 in the pre- and post-menopausal groups respectively (P < 0.05). In a multivariate analysis, menopause (P < 0.05), and also serum insulin levels (P < 0.01) and smoking (P < 0.05) were found to have independent significant associations to the stiffness index. In conclusion, menopause is associated with reduced elasticity of the carotid arteries in 50-year-old women.
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| 47. |
- Jönsson, Björn, 1951-, et al.
(författare)
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Is oscillometric ankle pressure reliable in leg vascular disease?
- 2001
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 21:2, s. 155-163
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0·52 was used, the mean difference between CW Doppler and oscillometry was 1·7 mmHg [range −19 to +27, limits of agreement (2 SD) 21·1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28·8 mmHg [range –126 to +65, limits of agreement 82·8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.
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| 48. |
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| 49. |
- Kurland, Lisa, 1960-, et al.
(författare)
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Polymorphisms in the renin-angiotensin system and endothelium-dependent vasodilation in normotensive subjects
- 2001
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 21:3, s. 343-349
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Our aim was to test the hypothesis that genes encoding components in the renin-angiotensin system influence endothelial vasodilatory function. METHODS: In 59 apparently healthy, normotensive individuals, endothelium-dependent vasodilation (EDV) and endothelial-independent vasodilation (EIDV) was evaluated by infusing metacholine and sodium nitroprusside into the brachial artery. Forearm blood flow was measured by venous occlusion plethysmography. The ACE insertion (I)/deletion (D) polymorphism, the T174M and M235T angiotensinogen restriction fragments length polymorphisms, the angiotensin II receptor type 1 (AT1R) A1166C, and the aldosterone synthase gene (CYP11B2) C-344T polymorphisms were analysed. RESULTS: When analysing the ACE, the two angiotensinogen and the aldosterone synthase CYP11B2 genotypes independently, no significant association with endothelial vasodilatory function was found. However, a significant reduction in endothelium-dependent vasodilation was observed in the subjects (n=9) with the ACE D allele and the angiotensinogen T174M genotype (P<0.05). Subjects with the AT1R genotype AC showed a reduction in both EDV (P=0.05) and EIDV (P=0.04) when compared with those with the AA genotype. CONCLUSIONS: The subjects with the ACE D allele in combination with the angiotensinogen T174M genotype are associated with a reduced EDV. This together with the observation that the AC AT1R genotype is associated with a reduction in both EDV and EIDV, supports the hypothesis that endothelial vasodilatory function is influenced by genes in the renin-angiotensinogen system.
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| 50. |
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