Biomedical subjects

Stig A Slørdahl

Publications and source records attributed to Stig A Slørdahl.

7 recordsLinked to original sources

PubMed2006

Noninvasive myocardial strain measurement by speckle tracking echocardiography: validation against sonomicrometry and tagged magnetic resonance imaging.

OBJECTIVES: The aim of this study was to validate speckle tracking echocardiography (STE) as a method for angle-independent measurement of regional myocardial strain, using sonomicrometry and magnetic resonance imaging (MRI) tagging as reference methods. BACKGROUND: Tissue Doppler imaging allows non-invasive measurement of myocardial strain in the left ventricle (LV), but is limited by angle dependency. METHODS: Strain measurements with STE were obtained by a custom-made program that allowed tracking of two-dimensional motion of speckle patterns in a B-mode image. In anesthetized dogs, we compared LV long- and short-axis measurements by STE to sonomicrometry during preload changes and regional myocardial ischemia. Measurements in the two orthogonal axes were obtained simultaneously in a single imaging plane. In human subjects, long-axis strain by STE and MRI tagging were compared in multiple segments of the LV. RESULTS: In the experimental study there was good correlation and agreement between STE and sonomicrometry for systolic strain in the long axis (r = 0.90, p < 0.001; 95% limits of agreement -4.4% to 5.0%) and systolic shortening in the short axis (r = 0.79, p < 0.001; -5.6% to 5.1%). In the clinical study, 80% of the segments could be analyzed, and correlation and agreement between STE and MRI tagging were good (r = 0.87, p < 0.001; -9.1% to 8.0%). CONCLUSIONS: Speckle tracking echocardiography provides accurate and angle-independent measurements of LV dimensions and strains and has potential to become a clinical bedside tool for quantifying myocardial strain.

Adult↗

PubMed2006

A single weekly bout of exercise may reduce cardiovascular mortality: how little pain for cardiac gain? 'The HUNT study, Norway'.

BACKGROUND: The observation that exercise training reduces cardiovascular mortality is robust and consistent, but the amount and intensity of exercise that is required for risk reduction is not yet resolved. METHODS: We studied the association between the amount and intensity of exercise and cardiovascular mortality in 27 143 men and 28 929 women who were free from known cardiovascular disease at the beginning of follow-up between 1984 and 1986. The relative risk of death was calculated as the rate of death among participants within a given physical activity category compared with the rate of death in the reference category (no physical activity). We used Cox regression analysis to adjust for age and other potentially confounding factors. RESULTS: After 16 years (SD 4 years) of follow-up, 2946 men (10.8%) and 2486 women (8.6%) had died from ischaemic heart disease or stroke. A single weekly bout of exercise of high intensity reduced the risk of cardiovascular death, both in men [relative risk (RR) 0.61, 95% confidence interval (CI) 0.49-0.75], and women (RR 0.49, 95% CI 0.27-0.89), compared with those who reported no activity. There was no additional benefit from increasing the duration or the number of exercise sessions per week. The risk reduction related to exercise increased with increasing age in men, but not in women. CONCLUSION: These results challenge the current recommendation that expenditure of at least 1000 kcal per week is required to achieve exercise-induced protection against premature cardiovascular mortality.

Adult↗

PubMed2005

Effective training for patients with intermittent claudication.

OBJECTIVE: Current guidelines for treatment of intermittent claudication (IC) do not include a specific recommendation for the intensity of exercise therapy. Thus, the purpose of this study was to determine the relative effectiveness of high versus low intensity exercise for patients with IC, and further to study the effect of such training on blood flow to the legs during exercise. DESIGN: The effect of eight weeks of supervised endurance training was examined in 16 patients with IC. The patients were randomly assigned to training at intensities corresponding to either 60% or 80% of their peak oxygen consumption (VO2peak), respectively. RESULTS: VO2peak and time to exhaustion increased significantly (9% and 16%, respectively) more in the high intensity group (p<0.05). Blood flow to the legs did not change after training in any of the groups. CONCLUSION: High intensity training gave larger improvements in VO2peak and time to exhaustion than low intensity training. As blood flow did not change after the exercise program, it is likely that the observed different increase of VO2peak was due to changed mitochondrial oxidative capacity and/or skeletal muscle diffusive capacity.

Aged↗

PubMed2005

Endothelial function in highly endurance-trained and sedentary, healthy young women.

Endothelial function is reduced by age, chronic heart failure, coronary artery disease, hypertension or type 2 diabetes, and it is shown that aerobic exercise may reverse this trend. The effect of a high aerobic training status on endothelial function in young, healthy subjects is however less clear. The present study was designed to determine whether endothelial function is improved in highly endurance-trained young women compared to sedentary, healthy controls. Brachial artery diameter was measured in 16 endurance-trained (age: 23.7 +/- 2.5 years, maximal oxygen uptake (VO2max): 60.6 +/- 4.5 ml/kg per min) and 14 sedentary females (age: 23.7 +/- 2.1 years, VO2max: 40.5 +/- 5.6 ml/kg per min) at rest, during flow-mediated dilation (FMD) and after sublingual glycerol trinitrate administration, using high-resolution ultrasound. FMD did not differ between the endurance-trained and the sedentary females (14.8% vs 16.4%, p = NS), despite a substantial difference in VO2max of 50% (p < 0.001). The endurance-trained group possessed however, a 9% larger resting brachial artery diameter when adjusted for body surface area. The results of the present study suggest that endothelial function is well preserved in young, healthy women, and that a high aerobic training status due to long term aerobic training does not improve the dilating capacity any further.

Adult↗

PubMed2004

High intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease.

BACKGROUND: Increased aerobic exercise capacity appears to reduce both all-cause mortality and cardiovascular disease mortality. Physical exercise to improve peak oxygen uptake (VO2peak) is thus strongly recommended, however evidence regarding the most efficient training intensity for patients with coronary artery disease (CAD) is still lacking. The purpose of this randomized study was therefore to assess the effects of high intensity aerobic interval exercise compared to moderate intensity exercise, representing the same total training load, for increasing VO2peak in stable CAD-patients. METHODS: Twenty-one stable CAD-patients were randomized to supervised treadmill walking at either high intensity (80-90% of VO2peak) or moderate intensity (50-60% of VO2peak) three times a week for 10 weeks. RESULTS: After training VO2peak increased by 17.9% (P=0.012) in the high intensity group and 7.9% (P=0.038) in the moderate intensity group. The training-induced adaptation was significantly higher in the high intensity group (P=0.011). CONCLUSIONS: High intensity aerobic interval exercise is superior to moderate exercise for increasing VO2peak in stable CAD-patients. As VO2peak seems to reflect a continuum between health and cardiovascular disease and death, the present data may be useful in designing effective training programmes for improved health in the future.

Coronary Artery Disease↗

PubMed2004

Atrioventricular plane displacement in untrained and trained females.

PURPOSE: Female athletes often demonstrate changes in cardiac dimensions that are less prominent than in male athletes, and results from longitudinal studies are conflicting. The atrioventricular plane displacement (AVPD) in the heart is used as an index of left ventricular systolic function with the assumption that it is a more sensitive method for measuring myocardial contractility compared with left ventricular ejection fraction. The aim of the present study was to determine the effect of a short period of endurance training on cardiac dimensions in sedentary female subjects and to measure the AVPD at rest and during submaximal workload. METHODS: Twelve sedentary female subjects (21.9 +/- 1.3 yr, 168.8 +/- 3.5 cm, 64.0 +/- 6.6 kg, and 42.6 +/- 2.9 mL x kg(-1) x min(-1) in maximal oxygen uptake) were examined with echocardiography before and after a period of interval training (varying from 2 to 5 min at 90-95% of maximal heart rate, 3 d x wk(-1), 8 wk). RESULTS: Maximal oxygen uptake increased by 18% to 50.4 +/- 3.1 mL x kg(-1) x min(-1) (P < 0.001). Left ventricular mass increased from 123.9 to 139.2 g (P = 0.007). There was a significant increase in posterior wall thickness but no change in cavity size. The AVPD did not change at rest but increased significantly from 15.6 to 17.6 mm (P < 0.001) during exercise at 85-90% of maximal heart rate. CONCLUSION: This study shows that a short period of aerobic endurance training induces changes in the female heart, both in cardiac dimensions at rest and in left ventricular systolic function at submaximal workload. AVPD during submaximal exercise discriminate well between the untrained and trained healthy heart.

Adaptation, Physiological↗

PubMed2002

Ultrasound recorded axillary artery blood flow during elbow-flexion exercise.

PURPOSE: To characterize and evaluate the repeatability of ultrasound recorded blood flow in the axillary artery during one-arm dynamic elbow flexion. METHOD: 11 healthy women (23 +/- 0.9 yr, 168 +/- 1.7 cm, 63 +/- 1.1 kg) performed 90 degrees elbow flexion in supine position. Mean maximum blood velocity was recorded by ultrasound during and after two submaximal loads, representing 16 and 24% of maximal voluntary contraction, and after exhaustion (.VO(2peak))Axillary artery diameter was measured after each workload. Each subject was examined two times 8 wk apart. Oxygen uptake was measured during exercise. Values are mean +/- SE. RESULTS: Flow was not different in the two tests. Flow was 25% higher immediately after than during exercise at the submaximal workloads. Flow immediately after .VO(2peak) was 1420 +/- 79 mL.min(-1). Axillary artery diameter after .VO(2peak) was 8% larger than at rest. Coefficient of variation ranged from 11 to 23%, coefficient of repeatability ranged from 230 mL.min(-1) at rest to 940 mL.min(-1) after exercise. Coefficient of repeatability for artery diameter was 0.09 cm; coefficient of variation for diameter was about 4% at all recording times. CONCLUSION: The present study showed that ultrasound recordings of blood flow during dynamic elbow-flexion exercise were reproducible. The method can be used to study training-induced flow changes and can detect differences of about 130 mL.min(-1). Artery diameter seemed to increase as flow and load increased.

Adult↗