Publications by authors named "Viktor Hamrefors"

Background: Preserved ratio impaired spirometry (PRISm) is a spirometry pattern of interest regarding incident airflow obstruction and higher mortality risk. We applied a proteomic approach to gain more insight into the biological mechanisms associated with PRISm.

Methods: From the population-based Swedish Cardiopulmonary Bioimage Study (SCAPIS), participants in the Main (n=4835) and Pilot (n=1054) studies, were included as discovery and replication cohorts.

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Introduction: Exercise training is recommended as a complementary treatment in postural orthostatic tachycardia syndrome (POTS) according to international guidelines. However, less is known regarding how exercise training could successfully be implemented in clinical practice in patients with POTS. Thus, in the current study, we aim to assess the effect of a 16-week tailored exercise training programme in POTS.

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An abnormal blood pressure (BP) response on standing is associated with atherosclerotic cardiovascular disease (CVD). The role of physical activity (PA) on orthostatic BP-reactions and its relation to subclinical atherosclerosis is unclear. We aimed to assess the association between PA and orthostatic BP-reactions, and whether PA modifies the relationship between orthostatic BP-reactions and subclinical atherosclerosis.

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Aims: Orthostatic hypotension (OH) is an important differential diagnosis in unexplained syncope. Neurogenic OH (nOH) has been postulated to differ from non-neurogenic OH (non-nOH), yet pathophysiological differences are largely unexplored. We aimed to investigate aetiology and tilt table test (TTT)-induced haemodynamic responses in symptomatic OH patients.

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Background: There is a well-known comorbidity between chronic obstructive pulmonary disease (COPD) and coronary artery disease (CAD) which is only partially explained by common risk factors. Markers of cardiovascular autonomic dysfunction (CVAD), such as orthostatic hypotension and increased resting heart rate, are strongly associated with CAD. The autonomic nervous system also innervates the airways, and several studies have shown an association between autonomic dysfunction and COPD.

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Article Synopsis
  • Postural orthostatic tachycardia syndrome (POTS), frequently diagnosed after COVID-19, involves excessive heart rate increase when standing, without drops in blood pressure (BP). This study compared BP profiles of 100 POTS patients post-COVID-19 to 100 healthy controls.* -
  • The findings revealed that POTS patients had higher nighttime systolic BP and were more likely to experience daytime hypotensive episodes, with significant differences in circadian BP patterns.* -
  • Overall, the study suggests that individuals with post-COVID-19 POTS have disrupted BP regulation and higher average BP levels, indicating a need for further research on potential targeted BP treatments.*
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Objectives: To examine cardiovascular autonomic function in middle-aged people with long-term cervical and upper thoracic spinal cord injury (SCI) compared with the general population, and explore if the neurological level of injury (NLI) is related to cardiovascular autonomic function.

Design: Population-based cross-sectional study with matched controls.

Setting: Outpatient SCI unit in Southern Sweden.

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Background: The ankle-brachial index (ABI) is the ratio of the ankle and brachial systolic blood pressures. In the clinical setting, low ABI (< 0.9) is an indicator of peripheral atherosclerosis, while high ABI (> 1.

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Knowledge regarding the prevalence and shared and unique characteristics of the restrictive spirometric pattern (RSP) and preserved ratio impaired spirometry (PRISm) is lacking for a general population investigated with post-bronchodilator spirometry and computed tomography of the lungs. To investigate shared and unique features for RSP and PRISm. In the Swedish CArdioPulmonary bioImage Study (SCAPIS), a general population sample of 28,555 people aged 50-64 years (including 14,558 never-smokers) was assessed.

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Aims: The pathophysiology of orthostatic hypotension (OH), a common clinical condition, associated with adverse outcomes, is incompletely understood. We examined the relationship between OH and circulating endostatin, an endogenous angiogenesis inhibitor with antitumour effects proposed to be involved in blood pressure (BP) regulation.

Methods And Results: We compared endostatin levels in 146 patients with OH and 150 controls.

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Gastrointestinal (GI) symptoms are common in postural orthostatic tachycardia syndrome (POTS). We aimed to explore the prevalence and severity of GI symptoms in POTS, and to investigate immunological factors, hemodynamic findings, and their possible association with GI symptoms in POTS. Forty-three patients (93% female, median age 30.

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Postural Orthostatic Tachycardia Syndrome (POTS) reflects an autonomic dysfunction, which can occur as a complication to COVID-19. Our aim was to examine gastrointestinal symptoms and gut microbiota composition in patients with POTS and post-acute COVID-19 syndrome (PACS), compared with controls. POTS patients (n = 27), PACS patients (n = 32) and controls (n = 39) delivered fecal samples and completed a 4-day food diary, irritable bowel syndrome-severity scoring system (IBS-SSS), and visual analog scale for IBS (VAS-IBS).

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Background: Previous studies have shown that the ratio between alveolar volume (V) and total lung capacity (TLC) reflects ventilation heterogeneity in subjects with chronic obstructive pulmonary disease (COPD). However, the ratio and its correlation to respiratory symptoms had to our knowledge not previously been investigated in subjects with mild chronic airflow obstruction or without airflow obstruction (normal ratio FEV/VC). The purpose of this study was to investigate potential connection between V/TLC and respiratory symptoms, smoking habits and lung function parameters in subjects with normal spirometry and with mild chronic airflow obstruction.

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Reduced lung function is associated with cardiovascular mortality, but the relationships with atherosclerosis are unclear. The population-based Swedish CArdioPulmonary BioImage study measured lung function, emphysema, coronary CT angiography, coronary calcium, carotid plaques and ankle-brachial index in 29,593 men and women aged 50-64 years. The results were confirmed using 2-sample Mendelian randomization.

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Whereas autonomic dysfunction and the metabolic syndrome are clinically associated, the relationships with the plasma metabolome is unknown. We explored the association between orthostatic blood pressure responses and 818 plasma metabolites in middle-aged subjects from the general population. We included 3803 out of 6251 subjects (mean age, 57 years; 52% women) from the Malmö sub-cohort of The Swedish CardioPulmonary bioImage Study with information on smoking habits, diabetes, antihypertensive drug treatment, anthropometrics, hemodynamic measurements and 818 plasma metabolites (mass-spectrometry).

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Tilt table testing (TTT) has been used for decades to study short-term blood pressure (BP) and heart rate regulation during orthostatic challenges. TTT provokes vasovagal reflex in many syncope patients as a background of widespread use. Despite the availability of evidence-based practice syncope guidelines, proper application and interpretation of TTT in the day-to-day care of syncope patients remain challenging.

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Aims: Syncope is a common condition with many possible causes, ranging from benign to life-threatening aetiologies. Establishing a diagnosis can be difficult, and specialized syncope units, using cardiovascular autonomic tests (CATs), including a head-up tilt test, can increase the diagnostic yield. However, up to one-fifth of examined patients have inconclusive CAT results.

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Background: Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous condition predominantly affecting autonomic control of the cardiovascular system. Its extensive symptom diversity implies multi-organ involvement that interacts in ways still requiring full exploration. Current understanding of POTS pathophysiology suggests alterations in the renin-angiotensin-aldosterone system as a possible contributing factor.

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Article Synopsis
  • - The study aimed to investigate how physical activity and sedentary time relate to autonomic function, specifically measured through the deep breathing test (DBT), among a group of 4325 individuals aged 50-64.
  • - Results showed that higher sedentary time was linked to lower measures of heart rate variability (HRV) and respiratory sinus arrhythmia (RSA), indicating poorer autonomic function, particularly after analyzing by age and sex factors.
  • - However, after accounting for heart rate adjustments, these associations lost significance, suggesting that the impact of physical activity on cardiovagal function is closely linked to heart rate levels.
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Postbronchodilator spirometry is used for the diagnosis of chronic obstructive pulmonary disease. However, prebronchodilator reference values are used for spirometry interpretation. To compare the resulting prevalence rates of abnormal spirometry and study the consequences of using pre- or postbronchodilator reference values generated within SCAPIS (Swedish CArdioPulmonary bioImage Study) when interpreting postbronchodilator spirometry in a general population.

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Article Synopsis
  • * Results show that patients with reflex syncope had significantly lower 24-hour systolic BP and pulse pressure, but higher diastolic BP, along with more frequent daytime systolic BP drops below 90 mm Hg compared to controls.
  • * The findings suggest that specific BP profiles, particularly a low systolic BP and pulse pressure, are associated with reflex syncope, indicating the potential use of ambulatory BP monitoring as a diagnostic tool for this condition.
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Objective: Orthostatic hypotension and resting heart rate (RHR) are associated with cardiovascular disease (CVD). However, it is unknown how these factors relate to subclinical CVD. We examined the relationship between orthostatic blood pressure (BP) response, RHR and cardiovascular risk factors, including coronary artery calcification score (CACS) and arterial stiffness, in the general population.

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Introduction: Diffuse peripheral neuropathy is a well-known complication of several conditions, whereas many patients have peripheral neuropathy of unknown etiology and pathophyisology. Increased knowledge of mechanisms may provide insight into enteric neuropathy with gastrointestinal dysmotility. The aim of the present systematic review was to identify mechanisms behind diffuse idiopathic peripheral neuropathies in humans.

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