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  • 51.
    Mörner, Stellan
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Rask, Peter
    Olofsson, Bert-Ove
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Kazzam, Elsadig
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Waldenström, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Parasympathetic dysfunction in hypertrophic cardiomyopathy assessed by heart rate variability: comparison between short-term and 24-h measurements2005In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 25, no 2, p. 90-99Article in journal (Other academic)
    Abstract [en]

    In this study, we evaluate cardiac autonomic function in hypertrophic cardiomyopathy (HCM) by assessing heart rate variability (HRV), comparing a short-term laboratory method with an ambulatory (24-h) method, in patients with and without beta-blockade. Reduced HRV is a risk factor for adverse events in some cardiac diseases, but is not a proven risk indicator in HCM. Analysis of HRV has been based on either short- or long-term electrocardiographic recordings and previous studies in HCM have shown conflicting results. There is no consensus on which method to prefer, and we evaluate, for the first time, both short- and long-term analyses in patients with HCM. Long- and short-term HRV analyses were performed in 43 patients with HCM. They were divided in two groups, 22 patients on beta-blockade and 21 non-treated patients. As controls, 121 healthy subjects were used. Young patients without beta-blockade showed a reduction in HRV parameters reflecting parasympathetic function, both in the short- and long-term registrations, which was attenuated by beta-blockade. Parasympathetic autonomic regulation was found to be impaired in young patients with HCM. This may be of clinical relevance as abnormal autonomic function might be a substrate for malignant dysrhythmias. The impairment was attenuated by beta-blockade, which might indicate a clinically useful effect. We also show that short- and long-term methods yield similar results, suggesting that a short-term registration might be sufficient to assess HRV in patients with HCM.

  • 52.
    Nicoll, Rachel
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Schmermund, A.
    Cardiology, Bethanian Hospital, Frankfurt, Germany.
    Diederichsen, A.
    Cardiology, Odense University Hospital, Odense, Denmark.
    Mickley, H.
    Cardiology, Odense University Hospital, Odense, Denmark.
    Overhus, K.
    Cardiology, Odense University Hospital, Odense, Denmark.
    Zamorano, P.
    Cardiology, University Hospital Ramón y Cajal Carretera, Madrid, Spain.
    Gueret, P.
    Cardiology, Hôpital Henri Mondor Creteil, France.
    Maffi, E.
    Cardiology, Giovanni XXIII Hospital, Italy.
    Cademartiri, F.
    Cardiology, Giovanni XXIII Hospital, Italy.
    Henein, Michael
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Euro-ccad: Differing conventional atherosclerosis risk factors for coronary calcification depending on degree of luminal stenosis2014In: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 235, no 2, p. E81-E82Article in journal (Other academic)
  • 53.
    Nicoll, Rachel
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine. Ctr Heart, Umea, Sweden.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Zhao, Y.
    Diederichsen, A.
    Mickley, H.
    Ovrehus, K.
    Zamorano, P.
    Gueret, P.
    Schmermund, A.
    Maffei, E.
    Cademartiri, F.
    Budoff, M.
    Henein, M.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    The coronary calcium score is a more accurate predictor of significant coronary stenosis than conventional risk factors in symptomatic patients: Euro-CCAD study2016In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 207, p. 13-19Article in journal (Refereed)
    Abstract [en]

    Aims: In this retrospective study we assessed the predictive value of the coronary calcium score for significant (>50%) stenosis relative to conventional risk factors. Methods and Results: We investigated 5515 symptomatic patients from Denmark, France, Germany, Italy, Spain and the USA. All had risk factor assessment, computed tomographic coronary angiogram (CTCA) or conventional angiography and a CT scan for coronary artery calcium (CAC) scoring. 1539 (27.9%) patients had significant stenosis, 5.50 of whom had zero CAC. In 5074 patients, multiple binary regression showed the most important predictor of significant stenosis to be male gender (B = 1.07) followed by diabetes mellitus (B = 0.70) smoking, hypercholesterolaemia, hypertension, family history of CAD and age but not obesity. When the log transformed CAC score was included, it became the most powerful predictor (B = 1.25), followed by male gender (B = 0.48), diabetes, smoking, family history and age but hypercholesterolaemia and hypertension lost significance. The CAC score is a more accurate predictor of >50% stenosis than risk factors regardless of the means of assessment of stenosis. The sensitivity of risk factors, CAC score and the combination for prediction of >50% stenosis when measured by conventional angiogram was considerably higher than when assessed by CTCA but the specificity was considerably higher when assessed by CTCA. The accuracy of CTCA for predicting >50% stenosis using the CAC score alone was higher (AUC 0.85) than using a combination of the CAC score and risk factors with conventional angiography (AUC 0.81). Conclusion: In symptomatic patients, the CAC score is a more accurate predictor of significant coronary stenosis than conventional risk factors.

  • 54.
    Nicoll, Rachel
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Zhao, Ying
    Diederichsen, A.
    Mickley, H.
    Ovrehus, K.
    Zamorano, J.
    Gueret, P.
    Schmermund, A.
    Maffei, E.
    Cademartiri, F.
    Budoff, M.
    Henein, Michael
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Gender and age effects on risk factor-based prediction of coronary artery calcium in symptomatic patients: a Euro-CCAD study2016In: Atherosclerosis, ISSN 0021-9150, E-ISSN 1879-1484, Vol. 252, p. 32-39Article in journal (Refereed)
    Abstract [en]

    Background and aims: The influence of gender and age on risk factor prediction of coronary artery calcification (CAC) presence in symptomatic patients is unclear.

    Methods: From the European Calcific Coronary Artery Disease (EURO-CCAD) cohort, we retrospectively investigated 6309 symptomatic patients, 62% male, from Denmark, France, Germany, Italy, Spain and USA. All had risk factor assessment and CT scanning for CAC scoring.

     Results: The prevalence of CAC among females was lower than among males in all age groups. Using multivariate logistic regression, age, dyslipidaemia, hypertension, diabetes and smoking were independently predictive of CAC presence in both genders. In addition to a progressive increase in CAC with age, the most important predictors of CAC presence were dyslipidaemia and diabetes (β = 0.64 and 0.63 respectively) in males and diabetes (β = 1.08) followed by smoking (β = 0.68) in females; these same risk factors were also important in predicting increasing CAC scores. There was no difference in the predictive ability of diabetes, hypertension and dyslipidaemia in either gender for CAC presence in patients aged <50 and 50-70 years. However, in patients aged >70, only dyslipidaemia predicted CAC presence in males and only smoking and diabetes were predictive in females. 

     

    Conclusion:  In symptomatic patients, there are significant differences in the ability of conventional risk factors to predict CAC presence between genders and between patients aged <70 and ≥70, indicating the important role of age in predicting CAC presence.

  • 55.
    Nicoll, Rachel
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Zhao, Ying
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Diederichsen, Axel
    Mickley, Hans
    Ovrehus, Kristian
    Zamorano, Jose
    Gueret, Pascal
    Schmermund, Axel
    Maffei, Erica
    Cademartiri, Filippo
    Budoff, Matt
    Henein, Michael
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Diabetes and male sex are key risk factor correlates of the extent of coronary artery calcification: a Euro-CCAD study2017In: Journal of diabetes and its complications, ISSN 1056-8727, E-ISSN 1873-460X, Vol. 31, no 7, p. 1096-1102Article in journal (Refereed)
    Abstract [en]

    Background and Aims: Although much has been written about the conventional cardiovascular risk factor correlates of the extent of coronary artery calcification (CAC), few studies have been carried out on symptomatic patients. This paper assesses the potential ability of risk factors to associate with an increasing CAC score. Methods: From the European Calcific Coronary Artery Disease (Euro-CCAD) cohort, we retrospectively investigated 6309 symptomatic patients, 62% male, from Denmark, France, Germany, Italy, Spain and the USA. All had conventional cardiovascular risk factor assessment and CI scanning for CAC scoring. Results: Among all patients, male sex (OR = 4.85, p < 0.001) and diabetes (OR = 236, p < 0.001) were the most important risk factors of CAC extent, with age, hypertension, dyslipidemia and smoking also showing a relationship. Among patients with CAC, age, diabetes, hypertension and dyslipidemia were associated with an increasing CAC score in males and females, with diabetes being the strongest dichotomous risk factor (p < 0.001 for both). These results were echoed in quantile regression, where diabetes was consistently the most important correlate with CAC extent in every quantile in both males and females. To a lesser extent, hypertension and dyslipidemia were also associated in the high CAC quantiles and the low CAC quantiles respectively. Conclusion: In addition to age and male sex in the total population, diabetes is the most important correlate of CAC extent in both sexes.

  • 56.
    Obayashi, K
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Marcus
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Okamoto, S
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Ando, Y
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Hemodynamic responses after tilt reversal in FAP2011In: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, E-ISSN 1744-2818, Vol. 18, no Suppl 1, p. 161-163Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to evaluate hemodynamic responses after tilt reversal in familial amyloid polyneuropathy (FAP). Systolic blood pressure (BP) and heart rate variability (HRV) were analyzed in the baseline, 70-degree upright position, and after tilt reversal in 10 patients with FAP and 14 healthy controls. Maximum systolic BP after tilt reversal was increased in FAP as compared to baseline (BP overshoot), whereas controls showed a significantly lower BP overshoot. In all states, all HRV parameters were significantly lower than those of the controls. In a linear regression analysis adjusted for age, we found a significant inverse relation between BP overshoot and HRV in all three states. Five patients presented atrial arrhythmia precluding HRV analysis: four of those presented BP overshoots 12 mmHg. BP overshoot may be a useful marker to assess the progression of cardiac autonomic dysfunction, especially since heart arrhythmia in many patients with FAP prevents HRV analysis.

  • 57.
    Obayashi, Konen
    et al.
    Department of Diagnostic Medicine, Graduate School of Life Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Marcus
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Okamoto, Sadahisa
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Ando, Yukio
    Department of Diagnostic Medicine, Graduate School of Life Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Blood pressure overshoot after tilt reversal in patients with familial amyloidotic polyneuropathy2011In: Hypertension Research, ISSN 0916-9636, E-ISSN 1348-4214, Vol. 34, no 1, p. 133-138Article in journal (Refereed)
    Abstract [en]

    The pathophysiology of the hemodynamic responses to postural stress in familial amyloidotic polyneuropathy (FAP) remains to be elucidated. The aim of the study was to evaluate hemodynamic responses after tilt reversal in FAP. Systolic blood pressure (BP) and heart rate variability (HRV) were analyzed in the baseline, 70° upright position, and after tilt reversal in 15 FAP patients and 14 healthy controls. Beat-to-beat BP was recorded with a Finapres device. Maximum systolic BP after tilt reversal was increased with 22±13 mm Hg in FAP patients as compared with baseline (BP overshoot), whereas controls showed a significantly lower BP overshoot (8±6 mm Hg, P<0.001). In all states, total spectral power and the power of the low and high frequency components were all significantly lower than those of the controls (P<0.01). In a linear regression analysis adjusted for age, we found a significant inverse relation between BP overshoot and HRV (total spectral power, power of the low-frequency and high-frequency components) in all three states (standardized β between -0.74 to -0.53, P<0.01). Five FAP patients presented a trial arrhythmia precluding HRV analysis: four of those presented BP overshoots 12 mm Hg. BP overshoot may be a marker to assess the progression of cardiac autonomic dysfunction, especially as heart arrhythmia in many FAP patients prevent HRV analysis. In addition, assessment of the post-tilt BP reaction points to possible treatment modalities for orthostatic hypotension at least in the early stages of the disease.

  • 58.
    Rydberg, Annika
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Paediatrics.
    Karlsson, Markus
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Wiklund, Urban
    Can analysis of heart rate variability predict arrhythmia in children with fontan circulation?2008In: Pediatric Cardiology, ISSN 0172-0643, E-ISSN 1432-1971, Vol. 29, no 1, p. 50-55Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to examine whether changes in heart rate variability (HRV) can predict arrhythmias in children who have undergone the Fontan procedure. The study included 15 children with total cavopulmonary connection. All examinations included echocardiography and 24-h ambulatory electrocardiogram with power spectral analysis of HRV and Poincaré plots (plots of each R-R interval as a function of the previous R-R interval). Six patients developed supraventricular tachycardia (four or more consecutive supraventricular beats). One patient was excluded from the study due to the development of bradycardia, necessitating placement of a pacemaker. Compared to the arrhythmia group, the patients without arrhythmias (n = 8) exhibited a significant difference in the standard deviation of instantaneous beat-to-beat R-R interval variability (= 0.02). Poincaré plots of patients without arrhythmias showed a typical torpedo- or comet-shaped pattern, whereas the arrhythmia group showed a more complex pattern. Although this study examined only a few subjects, needing confirmation by larger studies, it does indicate that patients who develop arrhythmias after receiving the Fontan procedure show a different Poincaré pattern compared to the nonarrhythmic group—even before the arrhythmia can be detected using the conventional Holter procedure. Routine follow-up using the Holter procedure and Poincaré plot analysis could help detect early arrhythmias.

  • 59.
    Sonntag-Öström, Elisabet
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine. Umeå University, Arctic Research Centre at Umeå University.
    Nordin, Maria
    Umeå University, Faculty of Social Sciences, Department of Psychology.
    Lundell, Ylva
    Dolling, Ann
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Karlsson, Marcus
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Carlberg, Bo
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Slunga Järvholm, Lisbeth
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Restorative effects of visits to urban and forest environments in patients with exhaustion disorder2014In: Urban Forestry & Urban Greening, ISSN 1618-8667, E-ISSN 1610-8167, Vol. 13, no 2, p. 344-354Article in journal (Refereed)
    Abstract [en]

    This experimental study investigated differences in perceived restorativeness, mood, attention capacity and physiological reactions when visiting city and forest environments. Twenty female patients diagnosed with exhaustion disorder visited three different forest environments and one city environment in randomized order. They performed a standardized 90-min test procedure in each of these environments. Evaluation of the environments and psychological effects in mood were studied with self-administered questionnaires. Attention capacity was studied with Necker Cube Pattern Control task. Physiological responses were measured with regularly scheduled controls of heart rate and blood pressure, and a single test of heart rate recovery. Visits to the forest environments were perceived as significantly more restorative, enhancing mood and attention capacity compared to the city. This also applies to the results of heart rate and to some extent to the results of the diastolic blood pressure. The results from this experimental study support our hypothesis that short visits to forest environments enhance both psychological and physiological recovery and that visits to forest environments are likely to be beneficial when suffering from exhaustion disorder. 

  • 60.
    Svenmarker, Staffan
    et al.
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Häggmark, Sören
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Johansson, Göran
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Axelsson, B.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Haney, Michael
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Anaesthesiology.
    Regional changes in cerebral blood flow oxygenation can indicate global changes in cerebral blood flow during coronary artery occlusion in juvenile pigs2014In: Physiological Measurement, ISSN 0967-3334, E-ISSN 1361-6579, Vol. 35, no 7, p. 1439-1450Article in journal (Refereed)
    Abstract [en]

    Near infrared spectroscopy (NIRS) is a widely employed method for assessment of regional cerebral oxygenation (R(c)StO(2)). RcStO(2) values are expected to vary with changes in the relative amount of oxyhaemoglobin. The present experimental study aimed to assess the response of RcStO(2) to controlled alterations of carotid blood flow (CQ). Landrace pigs were anesthetized followed by surgical preparation. Cyclic variations in cardiac output were accomplished by intermittently occluding the main stem of the left coronary artery. A flow measurement probe for assessing CQ was placed around the left carotid artery. One NIRS probe was placed on the left ipsilateral forehead to assess regional cerebral oximetry. Simultaneous registration of CQ and RcStO(2) was conducted. There was a strong correlation for variation in CQ and RcStO(2) signal values. Based on coherence analysis the fraction of power of the RcStO(2) that was coherent with the CQ signal reached 0.84 - 0.12 (P < 0.05) for frequencies lower than 0.1 Hz. The agreement of the sampleto- sample co-variation, as assessed by the Pearson correlation coefficient, was 0.83 +/- 0.08 (P < 0.05). One explanatory component for variations in cerebral oxygenation verified by NIRS should be attributed to variations in the cerebral blood flow.

  • 61.
    Valham, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Mooe, Thomas
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Rabben, Terje
    Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Clinical Neurophysiology.
    Stenlund, Hans
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Public Health Sciences.
    Wiklund, Urban
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Franklin, Karl A
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Pulmonary Medicine.
    Increased risk of stroke in patients with coronary artery disease and sleep apnea: a 10-year follow-up2008In: Circulation, ISSN 0009-7322, E-ISSN 1524-4539, Vol. 118, no 9, p. 955-960Article in journal (Refereed)
    Abstract [en]

    Background The effect of sleep apnea on mortality and cardiovascular morbidity is mainly unknown. We aimed to study whether sleep apnea is related to stroke, death, or myocardial infarction in patients with symptomatic coronary artery disease.

    Methods and Results A total of 392 men and women with coronary artery disease referred for coronary angiography were examined by use of overnight sleep apnea recordings. Sleep apnea, defined as an apnea-hypopnea index ≥5, was recorded in 54% of the patients. All patients were followed up prospectively for 10 years, and no one was lost to follow-up. Stroke occurred in 47 (12%) of 392 patients during follow-up. Sleep apnea was associated with an increased risk of stroke, with an adjusted hazard ratio of 2.89 (95% confidence interval 1.37 to 6.09, P=0.005), independent of age, body mass index, left ventricular function, diabetes mellitus, gender, intervention, hypertension, atrial fibrillation, a previous stroke or transient ischemic attack, and smoking. Patients with an apnea-hypopnea index of 5 to 15 and patients with an apnea-hypopnea index ≥15 had a 2.44 (95% confidence interval 1.08 to 5.52) and 3.56 (95% confidence interval 1.56 to 8.16) times increased risk of stroke, respectively, than patients without sleep apnea, independent of confounders (P for trend=0.011). Death and myocardial infarction were not related to sleep apnea. Intervention in the form of coronary artery bypass grafting or percutaneous coronary intervention was related to a longer survival but did not affect the incidence of stroke.

    Conclusions Sleep apnea is significantly associated with the risk of stroke among patients with coronary artery disease who are being evaluated for coronary intervention.

  • 62.
    van den Berg, Johannes
    et al.
    Umeå University, Faculty of Medicine, Public Health and Clinical Medicine.
    Neely, Gregory
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Radiation Sciences.
    Landström, Ulf
    Heart rate variability during sedentary work and sleep in normal and sleep-deprived states2005In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 25, no 1, p. 51-57Article in journal (Refereed)
    Abstract [en]

    The possibility of using heart rate variability (HRV) as an indicator of sleepiness was investigated by analysing heart rate (HR) activity and electroencephalography (EEG) recordings from 10 individuals who performed a monotonous attention task for 120 min in both sleep-deprived and rested states. In both conditions, measurements were collected during 60 min of sleep immediately following a 120 min of non-sleep (awake phase). Although HR decreased significantly in both the rested and the sleep-deprived states during the awake phase, HR significantly changed sooner when subjects were sleep-deprived than when they were rested. No significant changes in HRV were found during the awake phase; however, HRV correlated significantly with alpha and theta power densities when rested but not when sleep-deprived. During the sleep phase, the total HRV and very low and low frequency HRV components significantly decreased approximately 40 min after sleeping in the sleep-deprived condition. These HRV components were also significantly and negatively correlated with delta power densities. HRV does not seem to be a viable indicator of sleepiness; however, HRV may be useful for determining sleep stages.

  • 63.
    Vanoli, Davide
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Lindqvist, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Henein, Michael
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Näslund, Ulf
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Fully automated on-screen carotid intima-media thickness measurement: a screening tool for subclinical atherosclerosis2013In: Journal of Clinical Ultrasound, ISSN 0091-2751, E-ISSN 1097-0096, Vol. 41, no 6, p. 333-339Article in journal (Refereed)
    Abstract [en]

    Purpose Carotid intima-media thickness (CIMT) is generally considered an appropriate direct vascular method for cardiovascular risk assessment. The objective of this study was to evaluate the feasibility and reproducibility of a newly developed automated on-screen carotid ultrasound with respect to manual measurement with a conventional system.

    Methods We assessed CIMT in 50 consecutive patients (age 62 +/- 5 years, range 21-79 years, 36 men) twice, using a newly developed automated ultrasound (CardioHealth Station) and a conventional system with manual measurement (Acuson, Sequoia). For each patient, three frozen frames of the distal 10 mm of the right and left common carotid arteries were acquired on the two systems, by operators blinded to each other. The average of the mean value of three readings of each system was calculated.

    Results The intraclass correlation coefficient of the interoperator variability was 0.95 and 0.94 for the automated and manual measurements, respectively. The comparative coefficient of variation of the interoperator variability was 8.2 and 8.7% for the automated and manual measurements, respectively. There was no clinically relevant difference between measurements obtained by the two systems (intraclass correlation coefficient=0.98). The acquisition time of the automated system was significantly shorter than the conventional system (p<0.01).

    Conclusions Fully automated on-screen measurements of CIMT are feasible, faster, and as reproducible as conventional manual measurements and may be suitable and cost-effective for screening application in community medicine.

  • 64.
    Vanoli, Davide
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Lindqvist, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Henein, Michael
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Näslund, Ulf
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Successful novice's training in obtaining accurate assessment of carotid IMT using an automated ultrasound system2014In: European Heart Journal Cardiovascular Imaging, ISSN 2047-2404, E-ISSN 2047-2412, Vol. 15, no 6, p. 637-642Article in journal (Refereed)
    Abstract [en]

    Aims The aim of this study was to assess the feasibility and learning curve of training novice operators in using automated ultrasound to achieve satisfactory carotid intima-media thickness (CIMT) measurements.

    Methods and results Four novices underwent 4 weeks carotid ultrasound training using a newly developed automated ultrasonograph. A longitudinal B-mode image of the distal right common carotid artery (CCA) was acquired in 96 patients. The interoperator CIMT reproducibility was analysed by the coefficient of variation (CV) and intraclass correlation coefficient (ICC) for every week and compared with that from an expert operator. The weekly mean CV of the measurements on the 24 patients made by all novices was consistently reduced: 0.06, 0.05, 0.03, and 0.02, respectively. For the expert, the mean CV was 0.02, 0.02, 0.03, and 0.02, respectively. The novices' standard deviation (SD) of CVs also reduced weekly from 0.04 in the first week to 0.01 in the last week (P < 0.05). The corresponding weekly variation in the SD for the expert was 0.02 for the first week to 0.01 in the last week (P = 0.27). The agreement between measurements made by the novices was expressed by the ICC being 0.97 (P < 0.001) in the first week and increased to 0.99 (P < 0.001) in the fourth week.

    Conclusion CIMT assessment by novices using an automated ultrasound could be reliably achievable after a short training period. These results may have encouraging implications when designing screening programmes for primary prevention in community health service.

  • 65.
    Wadell, Karin
    et al.
    Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Öhberg, Fredrik
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Bergmann, Eva
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Holmner, Åsa
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Blomberg, Anders
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Longitudinal, home-based study of lung function, saturation and disease-related symptoms in COPD2018In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 52Article in journal (Other academic)
    Abstract [en]

    Background: Many telehealth (TH) systems have been designed to identify signs of COPD exacerbations, but few previous studies have reported the nature of recorded lung function data and what variations to expect in stable versus unstable patients.

    Aims: To evaluate the nature of individual diurnal, day-to-day and long-term variation in important prognostic markers of COPD exacerbations in a heterogeneous patient group by employing a newly developed TH system.

    Methods: Eight women and five men with COPD performed measurements (FEV1, IC, SpO2 and CAT) three times per week during 4-6 months using the TH system. Feasibility was based on the repeatability and quality of the FEV1 and IC measurements, as defined by ERS/ATS guidelines. Short-term and long-term individual variations were assessed using the relative density and mean (SD) respectively.

    Results: Close to 1100 FEV1 and IC measurements respectively were performed during a total of 240 patient weeks. The 2SD ranges for intra-individual variation were ± 210 mL and ± 350 mL for FEV1 and IC respectively. The values both increased and decreased without corresponding influence on symptoms (CAT) or SpO2 and no exacerbation was reported. However, it was unusual with a decrease of more than 50 mL per measurement in FEV1 between three consecutive measurement days.

    Conclusions: This study reveals important and, to our knowledge, previously not reported information about short and long-term variability in lung function measurements in stable patients with COPD, of significance when defining criteria for detecting exacerbations with TH systems.

  • 66. Wedekind, D.
    et al.
    Kleyko, D.
    Osipov, E.
    Malberg, H.
    Zaunseder, S.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sparse Coding of Cardiac Signals for Automated Component Selection after Blind Source Separation2016In: / [ed] Murray, A, IEEE, 2016, p. 785-788Conference paper (Refereed)
    Abstract [en]

    Wearable sensor technology like textile electrodes provides novel ambulatory health monitoring solutions but most often goes along with low signal quality. Blind Source Separation (BSS) is capable of extracting the Electrocardiogram (ECG) out of heavily distorted multichannel recordings. However, permutation indeterminacy has to be solved, i.e. the automated selection of the desired BSS output. To that end we propose to exploit the sparsity of the ECG modeled as a spike train of successive heartbeats. A binary code derived from a two-item dictionary {peak, no peak} and physiological a-priori information temporally represents every BSS output component. The (best) ECG component is automatically selected based on a modified Hamming distance comparing the components' code with the expected code behavior. Non-standard ECG recordings from ten healthy subjects performing common motions while wearing a sensor garment were subsequently processed in 10 s segments with spatio-temporal BSS. Our sparsity-based selection RCODE achieved 98.1% heart beat detection accuracy (ACC) by selecting a single component each after BSS. Traditional component selection based on higher-order statistics (e.g. skewness) achieved only 67.6% ACC.

  • 67. Wedekind, Daniel
    et al.
    Kleyko, Denis
    Osipov, Evgeny
    Malberg, Hagen
    Zaunseder, Sebastian
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Robust Methods for Automated Selection of Cardiac Signals After Blind Source Separation2018In: IEEE Transactions on Biomedical Engineering, ISSN 0018-9294, E-ISSN 1558-2531, Vol. 65, no 10, p. 2248-2258Article in journal (Refereed)
    Abstract [en]

    Objective: Novel minimum-contact vital signs monitoring techniques like textile or capacitive electrocardiogram (ECG) provide new opportunities for health monitoring. These techniques are sensitive to artifacts and require handling of unstable signal quality. Spatio-temporal blind source separation (BSS) is capable of processing suchlike multichannel signals. However, BSS's permutation indeterminacy requires the selection of the cardiac signal (i.e., the component resembling the electric cardiac activity) after its separation from artifacts. This study evaluates different concepts for solving permutation indeterminacy.

    Methods: Novel automated component selection routines based on heartbeat detections are compared with standard concepts, as using higher order moments or frequency-domain features, for solving permutation indeterminacy in spatio-temporal BSS. BSS was applied to a textile and a capacitive ECG dataset of healthy subjects performing a motion protocol, and to the MIT-BIH Arrhythmia Database. The performance of the subsequent component selection was evaluated by means of the heartbeat detection accuracy (ACC) using an automatically selected single component.

    Results: The proposed heartbeat-detection-based selection routines significantly outperformed the standard selectors based on Skewness, Kurtosis, and frequency-domain features, especially for datasets containing motion artifacts. For arrhythmia data, beat analysis by sparse coding outperformed simple periodicity tests of the detected heartbeats. Conclusion: Component selection routines based on heartbeat detections are capable of reliably selecting cardiac signals after spatio-temporal BSS in case of severe motion artifacts and arrhythmia.

    Significance: The availability of robust cardiac component selectors for solving permutation indeterminacy facilitates the usage of spatio-temporal BSS to extract cardiac signals in artifact-sensitive minimum-contact vital signs monitoring techniques.

  • 68.
    Wiklund, Urban
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF). Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Olofsson, Bert-Ove
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Cardiac autonomic function does not improve after liver transplantation for familial amyloidotic polyneuropathy.2010In: Autonomic Neuroscience: Basic & Clinical, ISSN 1566-0702, E-ISSN 1872-7484, Vol. 156, no 1-2, p. 124-130Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: Liver transplantation is the only potentially curative treatment for familial amyloidotic polyneuropathy (FAP). We investigated cardiac autonomic function in 63 transplanted Swedish FAP patients. METHODS: Heart rate variability (HRV) was recorded between 1-17 (mean 8) months before, and 10-40 (mean 20) months after transplantation. HRV was analysed by power spectrum analysis, but only in patients without arrhythmia (n=38). RESULTS: Patients with moderate cardiac autonomic dysfunction showed a statistically significant reduction in HRV after transplantation, as compared to the pre-transplant recording. Patients with severe cardiac autonomic dysfunction presented unchanged HRV after liver transplantation. Twenty patients were excluded because they presented cardiac arrhythmia, five of these presented increased HRV after transplantation but had developed subtle arrhythmias, thus, they had not improved cardiac autonomic control. Five patients were excluded because they were pacemaker-treated. CONCLUSIONS: The reason why HRV decreased after transplantation remains unclear, but there are several possibilities: 1) liver transplantation did not stop the deterioration in cardiac autonomic function; 2) the deterioration continued until transplantation and was then halted; or 3) a sudden reduction in HRV occurred in connection with the transplantation procedure. Nonetheless, this study failed to disclose any improvement in cardiac autonomic function after liver transplantation for FAP.

  • 69.
    Wiklund, Urban
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Jensen, Steen M
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Abnormal heart rate variability and subtle atrial arrhythmia in patients with familial amyloidotic polyneuropathy2008In: Annals of Nonivasive Electrocardiology, Vol. 13, no 3, p. 249-256Article in journal (Refereed)
  • 70.
    Wiklund, Urban
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Kadkhodaee, Amir
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Andersson, Kennet
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Cardiorespiratory Coherence Analysis of Abnormal Heart Rate Responses during Deep Breathing2013In: 2013 COMPUTING IN CARDIOLOGY CONFERENCE (CINC), 2013, Vol. 40, p. 109-112Conference paper (Refereed)
    Abstract [en]

    Although the heart rate variability (HRV) normally is highly synchronised with respiration during deep breathing, in patients with transthyretin amyloidosis we occasionally observe abnormal heart rate responses due to subtle arrhythmias, This study evaluates the use of cardiorespiratory coherence analysis for automatic detection of these abnormal patterns.

  • 71.
    Wiklund, Urban
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Kadkhodaee, Amir
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Andersson, Kennet
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Suhr, Ole B.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Section of Medicine.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Normal scores of deep breathing tests: beware of dysrhythmia in transthyretin amyloidosis2018In: Amyloid: Journal of Protein Folding Disorders, ISSN 1350-6129, E-ISSN 1744-2818, Vol. 25, no 1, p. 54-61Article in journal (Refereed)
    Abstract [en]

    Background: The heart rate (HR) response to paced deep breathing (DB) is a common test of cardiac autonomic function, where high heart rate variability (HRV) is considered to reflect normal autonomic function. We evaluated the DB test in patients with hereditary transthyretin amyloid (ATTRm) amyloidosis, where autonomic dysregulation and atrial arrhythmias are common.Methods: Paced DB was performed during one minute (six breaths/min) in 165 recordings in adult ATTRm amyloidosis patients with the TTR Val30Met mutation, 42 hypertrophic cardiomyopathy (HCM) patients and 211 healthy subjects. HRV was scored by traditional DB indices and by a novel regularity index, estimating the fraction of the HRV that was coherent with the breathing pattern.Results: Twenty per cent of ATTRm amyloidosis patients presented with age-adjusted HRV scores within normal limits but poor regularity due to subtle atrial arrhythmias and cardiac conduction disturbances. Forty-seven per cent of ATTRm amyloidosis patients presented with HRV scores below normal limits, whereas HCM patients presented with higher HRV than ATTRm amyloidosis patients.Conclusions: Reduced HRV is common in ATTRm amyloidosis patients during DB, however, autonomic function cannot be evaluated in patients presenting with the combination of normal scores and low regularity, since their HR responses often reflects dysrhythmias.

  • 72.
    Wiklund, Urban
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Marcus
    Östlund, Nils
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Berglin, Lena
    Lindecrantz, Kaj
    Karlsson, Stefan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sandsjö, Leif
    Adaptive spatio-temporal filtering of disturbed ECGs: a multi-channel approach to heartbeat detection in smart clothing.2007In: Medical and Biological Engineering and Computing, ISSN 0140-0118, Vol. 45, no 6, p. 515-523Article in journal (Refereed)
  • 73.
    Wiklund, Urban
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Karlsson, Marcus
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Öström, Mats
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery. Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Forensic Medicine.
    Messner, Torbjörn
    Influence of energy drinks and alcohol on post-exercise heart rate recovery and heart rate variability2009In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 29, no 1, p. 74-80Article in journal (Refereed)
    Abstract [sv]

    Background: Media have anecdotally reported that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. This study investigated changes in the electrocardiogram (ECG) and heart rate variability after intake of an energy drink, taken in combination with alcohol and exercise.

    Methods: Ten healthy volunteers (five men and five women aged 19–30) performed maximal bicycle ergometer exercise for 30 min after: (i) intake of 0·75 l of an energy drink mixed with alcohol; (ii) intake of energy drink; and, (iii) no intake of any drink. ECG was continuously recorded for analysis of heart rate variability and heart rate recovery.

    Results: No subject developed any clinically significant arrhythmias. Post-exercise recovery in heart rate and heart rate variability was slower after the subjects consumed energy drink and alcohol before exercise, than after exercise alone.

    Conclusion: The healthy subjects developed blunted cardiac autonomic modulation after exercising when they had consumed energy drinks mixed with alcohol. Although they did not develop any significant arrhythmia, individuals predisposed to arrhythmia by congenital or other rhythm disorders could have an increased risk for malignant cardiac arrhythmia in similar situations.

  • 74.
    Wilén, Jonna
    et al.
    National Institute for Working Life, Umeå, Sweden.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology. National Institute for Working Life, Umeå, Sweden.
    Sandström, Monica
    National Institute for Working Life, Umeå, Sweden.
    Bjerle, Per
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology. Biomedical Engineering & Informatics, University Hospital, Umeå, Sweden.
    Stensson, Olov
    National Institute for Working Life, Umeå, Sweden.
    Lyskov, Eugene
    Centre for Musculoskeletal Research, University of Gävle, Sweden.
    Hansson Mild, Kjell
    National Institute for Working Life, Umeå, Sweden.
    Electromagnetic field exposure and health among RF plastic sealer operators2004In: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, Vol. 25, no 1, p. 5-15Article in journal (Refereed)
    Abstract [en]

    Operators of RF plastic sealers (RF operators) are an occupational category highly exposed to radiofrequency electromagnetic fields. The aim of the present study was to make an appropriate exposure assessment of RF welding and examine the health status of the operators. In total, 35 RF operators and 37 controls were included. The leakage fields (electric and magnetic field strength) were measured, as well as induced and contact current. Information about welding time and productivity was used to calculate time integrated exposure. A neurophysiological examination and 24 h ECG were also carried out. The participants also had to answer a questionnaire about subjective symptoms. The measurements showed that RF operators were exposed to rather intense electric and magnetic fields. The mean values of the calculated 6 min, spatially averaged E and H field strengths, in line with ICNIRP reference levels, are 107 V/m and 0.24 A/m, respectively. The maximum measured field strengths were 2 kV/m and 1.5 A/m, respectively. The induced current in ankles and wrists varied, depending on the work situation, with a mean value of 101 mA and a maximum measured value of 1 A. In total, 11 out of 46 measured RF plastic sealers exceeded the ICNIRP reference levels. RF operators, especially the ready made clothing workers had a slightly disturbed two-point discrimination ability compared to a control group. A nonsignificant difference between RF operators and controls was found in the prevalence of subjective symptoms, but the time integrated exposure parameters seem to be of importance to the prevalence of some subjective symptoms: fatigue, headaches, and warmth sensations in the hands. Further, RF operators had a significantly lower heart rate (24 h registration) and more episodes of bradycardia compared to controls.

  • 75.
    Wilén, Jonna
    et al.
    National Institute for Working Life, Umeå.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Radiation Sciences.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Surgical and Perioperative Sciences, Clinical Physiology.
    Sandström, Monica
    Umeå University, Faculty of Medicine, Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Changes in heart rate variability among RF plastic sealer operators.2007In: Bioelectromagnetics, ISSN 0197-8462, E-ISSN 1521-186X, Vol. 28, no 1, p. 76-79Article in journal (Refereed)
    Abstract [en]

    In a previous study, we showed that operators of radiofrequency (RF) plastic sealers, RF operators (n = 35) had a lower heart rate during nighttime compared to a control group (n = 37). We have analyzed the heart rate variability (HRV) on the same group of people to better understand the possible underlying rhythm disturbances. We found a significantly increased total HRV and very low frequency (VLF) power during nighttime among the RF operators compared to a control group. Together with our previous finding of a significantly lower heart rate during nighttime among the RF operators compared to the controls, this finding indicates a relative increase in parasympathetic cardiac modulation in RF operators. This could in turn be due to an adaptation of the thermoregulatory system and the cardiac autonomic modulation to a long-term low-level thermal exposure in the RF operators.

  • 76.
    Wixner, Jonas
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Karling, Pontus
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Rydh, Anders
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Diagnostic Radiology.
    Hornsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Anan, Intissar
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Suhr, Ole B.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Gastric emptying in hereditary transthyretin amyloidosis: the impact of autonomic neuropathy2012In: Neurogastroenterology and Motility, ISSN 1350-1925, E-ISSN 1365-2982, Vol. 24, no 12, p. 1111-e568Article in journal (Refereed)
    Abstract [en]

    Background: Gastrointestinal (GI) complications are common in hereditary transthyretin amyloidosis and an autonomic dysfunction has been considered to explain these symptoms. The aim of this study was to investigate the impact of autonomic neuropathy on gastric emptying in hereditary transthyretin amyloidosis and to relate these findings to nutritional status, GI symptoms, gender, and age at disease onset.

    Methods: Gastric emptying was evaluated with gastric emptying scintigraphy. Spectral analysis of the heart rate variability and cardiovascular responses after tilt test were used to assess the autonomic function. The nutritional status was evaluated with the modified body mass index (s-albumine x BMI).

    Key Results: Gastric retention was found in about one-third of the patients. A weak correlation was found between the scintigraphic gastric emptying rate and both the sympathetic (rs = -0.397, P < 0.001) and parasympathetic function (rs = -0.282, P = 0.002). The gastric emptying rate was slower in those with lower or both upper and lower GI symptoms compared with those without symptoms (median T50 123 vs 113 min, P = 0.042 and 192 vs 113 min, P = 0.003, respectively). Multiple logistic regression analysis showed that age of onset (OR 0.10, CI 0.020.52) and sympathetic dysfunction (OR 0.23, CI 0.100.51), but not gender (OR 0.76, CI 0.311.84) and parasympathetic dysfunction (OR 1.81, CI 0.724.56), contributed to gastric retention.

    Conclusions and Inferences: Gastric retention is common in hereditary transthyretin amyloidosis early after onset. Autonomic neuropathy only weakly correlates with gastric retention and therefore additional factors must be involved.

  • 77.
    Zhao, Ying
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Hörnsten, Rolf
    Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology.
    Lindqvist, Per
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Henein, Michael Y
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
    Left ventricular dyssynchrony is associated with reduced heart rate variability in familial amyloidotic polyneuropathy2012In: International Journal of Cardiology, ISSN 0167-5273, E-ISSN 1874-1754, Vol. 155, no 2, p. 272-278Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Cardiac complications are common in familial amyloidotic polyneuropathy (FAP), in which heart rate variability (HRV) is reduced. Although autonomic disturbances are well-established, mechanisms for reduced HRV, their relationship with left ventricular (LV) function in FAP are not well understood.

    METHODS: Twenty-nine FAP patients and 29 healthy controls were studied using Doppler echocardiography. Patients' and controls' HRV were studied using power spectral analysis from 24-hour Holter-ECG recordings.

    RESULTS: In FAP patients, all HRV parameters were lower (p<0.01 for all) than those in controls. Echocardiography showed a normal LV systolic function in patients. Relative filling time (FT/RR) was shorter (p<0.01) and total isovolumic time (t-IVT) was longer (p<0.01) in patients than in controls. E/Em was higher (p<0.01), as was Tei index (p=0.02) as compared to controls. T-IVT and Tei index correlated with stroke volume (SV) (r=-0.54, p<0.01 and r=-0.44, p<0.05, respectively) in patients. HRV was reduced in 9/29 (31%) patients, who had shorter FT/RR (p<0.01), longer t-IVT (p<0.01), higher Tei index (p=0.05), A wave (p<0.01) and E/Em (p<0.05) than in subjects without reduced HRV. FT/RR and t-IVT correlated with HRV spectral parameters (p<0.05 for all). The correlation between t-IVT and SV was stronger in patients with reduced HRV (r=-0.80, p<0.01) than in those without. QRS duration was not different in the two subgroups of patients.

    CONCLUSIONS: In a subset of patients with FAP, HRV was significantly reduced and appeared to be associated with shortened LV filling time and prolonged t-IVT, which reflect ventricular dyssynchrony, despite normal QRS. Thus, in addition to autonomic disturbances in FAP, ventricular dyssynchrony is another factor associated with reduced HRV. Correction of such disturbed ventricular function by cardiac resynchronization therapy may control patients' symptom.

  • 78.
    Öhberg, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Grip, Helena
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics.
    Sterner, Ylva
    Karlsson, J Stefan
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Gerdle, Björn
    Chronic whiplash associated disorders and neck movement measurements: an instantaneous helical axis approach.2003In: IEEE transactions on information technology in biomedicine, ISSN 1089-7771, E-ISSN 1558-0032, Vol. 7, no 4, p. 274-282Article in journal (Refereed)
    Abstract [en]

    This paper presents an assessment tool for objective neck movement analysis of subjects suffering from chronic whiplash-associated disorders (WAD). Three-dimensional (3-D) motion data is collected by a commercially available motion analysis system. Head rotation, defined in this paper as the rotation angle around the instantaneous helical axis (IHA), is used for extracting a number of variables (e.g., angular velocity and range, symmetry of motion). Statistically significant differences were found between controls and subjects with chronic WAD in a number of variables.

  • 79.
    Östlund, Nils
    et al.
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Suhr, Ole B
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences.
    Wavelet Coherence Detects Non-autonomic Heart Rate Fluctuations in Familial Amyloidotic Polyneuropathy.2007In: Conf Proc IEEE Eng Med Biol Soc, ISSN 1557-170X, Vol. 1, p. 4660-2Article in journal (Refereed)
  • 80.
    Östlund, Nils
    et al.
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Wiklund, Urban
    Umeå University, Faculty of Medicine, Department of Radiation Sciences, Radiation Physics. Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Yu, Jun
    Centre of Biostochastics, SLU.
    Karlsson, Stefan
    Umeå University, Faculty of Science and Technology, Centre for Biomedical Engineering and Physics (CMTF).
    Adaptive spatio-temporal filtration of bioelectrical signals2005In: Proceedings of The 27th Annual International Conferenceof the IEEE Engineering in Medicine and Biology Society, New York: IEEE Press, 2005, p. 5983-5986Conference paper (Refereed)
    Abstract [en]

    In this paper we show how independent component analysis (ICA) algorithms can be used to perform spatio-temporal filtration of electromyographic (EMG) and electrocardiographic (ECG) signals. The technique was used to decompose the EMG signals into motor unit action potential (MUAP) trains. From the 88 outputs of the adaptive spatio-temporal filtration, three groups of different MUAP train patterns were found. The technique was also used to obtain a fetus' ECG and showed better result compared to using ICA.

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