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- Erelund, Sofia, 1983-
(författare)
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Heart and lung function - in health and disease : methodological studies in clinical physiology
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The human heart and lungs constitute an intricate and dynamic system. Various clinical physiological examinations can be used to evaluate cardio-pulmonary function and identify abnormalities. Thus, it is important to understand how normal physiology presents, to be able to identify pathological findings. To distinguish normal from abnormal findings in a patient population compared to healthy controls, adequate, accurate and up-to-date reference materials are required. There is currently a lack of well-established sex and age specific reference materials that clearly state boundaries of normality for electrocardiography (ECG) variables. For lung function examinations there are several different reference materials available, being discordant between ethnicities. In addition, the relation between lung function, age, sex, and height has generally been difficult to model in an optimal way. This highlights the need for more adequate sex-specific models regarding age- and height-dependency of spirometry variables. Heart rate variability (HRV) is a method for evaluating the autonomic nervous system (ANS) and its influence on heart rate and blood pressure. Autonomic disturbances are characterized by an imbalance between the sympathetic and the parasympathetic nervous systems. It is well known that decreased HRV is associated with increased mortality. Autonomic imbalances are also associated with various pathological conditions, of which rheumatoid arthritis (RA) and ischemic heart disease (IHD) are studied in this thesis.The purpose of this thesis was to describe the properties of different clinical physiological examinations and to investigate reference values relating to cardiovascular and pulmonary function in healthy individuals regarding age and sex. In addition, the aim was to assess the relationship between HRV, RA and CVD both cross sectionally and longitudinally. In a subjectively healthy population (n=219) of varying age, there were age and sex-dependent differences in ECG examinations. This emphasizes former findings and supports the need to establish age- and sex-specific reference values in the future. Lung function examinations in subjectively healthy persons (n=285) support and emphasize that the reference values presented by the Global Lung function Initiative (GLI) underestimate the pulmonary function in the adult Swedish population. The study showed that the model used in GLI can be updated with new values that are specific for the Caucasian population in Sweden. Patients with RA (n=50) presented with lower HRV than healthy controls (n=100) during autonomic provocation tests, both at baseline examinations and after five years. This indicates a cardiac autonomic imbalance. Furthermore, increased systolic blood pressure was associated with reduced HRV, thus a decrease in HRV could be a risk marker for developing arterial hypertension in this patient group.Females with IHD (n=197) presented with lower HRV compared to controls (n=141) at baseline, and a higher mortality rate after 15 years. The higher mortality rate was only present in females < 60 years of age. For measurements obtained in the upright position, HRV was higher in females that died during follow-up compared to those who were alive. This thesis emphasizes the importance of validated and updated sex- and age- specific reference materials, and models that are well suited for different clinical physiological examinations. Additionally, HRV examinations exposed changes in the ANS related to RA as well as IHD, where findings were shown to be persistent over time and particularly pronounced during provocations. In the future, HRV assessment could be a useful tool to identify the increased risk of developing hypertension in patients with RA, or to customize treatment based on ANS response as the field of personalized medicine continues to evolve.
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| 2. |
- Lundström, Anna, 1984-
(författare)
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Autonomic cardiac control in long QT syndrome : clinical studies of arrhythmogenic triggers
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Long QT syndrome (LQTS) is an inherited cardiac disease characterized by prolonged cardiac repolarization and an increased risk for life-threatening arrhythmias. These arrhythmias are typically triggered by adrenergic stimuli, such as physical activity and intense emotions, implicating that the sympathetic part of the autonomic nervous system (ANS) is involved in arrhythmogenesis. However, symptoms also commonly occur swimming and diving, situations associated with dual activation of both branches of the ANS. This observation suggests that both sympathetic and parasympathetic physiological responses may contribute to the initiation of arrhythmias in individuals with LQTS.Aim: The overall aim of this thesis was to describe the cardiac autonomic response in LQTS patients during daily activities, exercise, and swimming, as well as to assess the presence of arrhythmias during activities in water. Methods: In all 4 studies electrocardiograms (ECGs) were recorded. In study I and II, a 24-hour ECG (Holter) system was used. In study III and IV, a waterproof 2-lead ECG device (Actiwave-Cardio) was used. In study I, ECGs were collected from adult LQTS patients (n = 44) and healthy controls (n = 44) during a submaximal bicycle exercise stress test. In study II, annual 24-hour ECG recordings (n = 575) during ordinary daily living was retrospectively collected in children with LQTS (n = 116). In study III, children with LQTS type 1 (LQT1) (n = 15) and age and sex matched healthy controls (n = 15) performed face immersion (FI), swimming, diving, and whole-body submersion (WBS). In study IV, healthy adolescents aged 15 years performed FI (n = 54) and ice-water immersion (IWI) of the body (n = 20).Heart rate responses and spectral analysis of heart rate variability (HRV) were assessed. HRV measures the beat-to-beat variation of the RR intervals of the heart, making it possible to non-invasively analyze the cardiac autonomic influence on the heart. The total power (PTOT) reflects all the variation during the recorded period. The high frequency (HF) component reflects parasympathetic activity, while the low frequency (LF) is influenced by both the sympathetic and parasympathetic activity.Results: In study I, LQTS patients had a decreased heart rate reduction and a lower PTOT, LF and HF than controls during the post-exercise phase. LQTS patients off beta-blocker (BB) treatment showed a lower HF and higher LF/HF ratio compared to LQTS patients on BB treatment. In study II, a correlation between heart rate and changes in HRV parameters was observed. At higher heart rates, the whole cohort of LQTS patients, as well as the subgroup of LQTS patients off BB, had lower HRV values than controls. A pattern was observed indicating that LQT1 patients had lower HF in the age group of 1-10 years, with this trend shifting as age increased, resulting in lower HF in the LQT2 patients aged 15-18 years. LQT1 girls aged 10-18 years had lower PTOT than LQT1 boys. Study III showed that LQT1 patients had a smaller reduction in heart rate during FI and WBS than controls. LQT1 patients had a lower HRV before, during and after FI and WBS than controls. In study IV, in healthy adolescents, supraventricular extrasystoles were relatively common during both FI and IWI, and 2 of 54 had ventricular bigeminy during FI. FI resulted in a more pronounced heart rate reduction compared to IWI.Conclusions: The results of these studies indicate that individuals with LQTS have an aberrant cardiac response to activities that affects the ANS. After exercise and in response to water activities, the parasympathetic effect on both the heart rate and HRV appears depressed in LQTS patients. Additionally, during everyday activities, LQTS patients generally have lower HRV values at higher heart rates compared to controls. These findings suggest that both branches of the ANS might be involved in arrhythmogenesis in this patient group, and that an increased understanding of the ANS role could improve patient management and treatment. The results from the ice-water study indicate that the ventricular arrhythmia risk is likely higher during whole-body submersion with apnea. The absence of arrhythmias in beta-blocked LQT1 patients indicates effective protection by their current treatment.
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| 4. |
- Alenius Dahlqvist, Jenny, et al.
(författare)
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Heart rate variability in children with fontan circulation : lateral tunnel and extracardiac conduit
- 2012
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Ingår i: Pediatric Cardiology. - New York : Springer-Verlag New York. - 0172-0643 .- 1432-1971. ; 33:2, s. 307-315
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Tidskriftsartikel (refereegranskat)abstract
- The technique in Fontan surgery has developed from the lateral tunnel (LT) toward the extracardiac conduit (EC) used to reduce long-term complications such as atrial arrhythmia and sinus node dysfunction. Heart rate variability (HRV) examines cardiac nervous activity controlling the sinus node. This study aimed to investigate HRV in a cohort of children with univentricular hearts, focusing on the relation between HRV and surgical procedure. For 112 children with Fontan circulation, HRV was analyzed using power spectral analysis. Spectral power was determined in three regions: very-low-frequency (VLF), low-frequency (LF), and high-frequency (HF) regions. Patients were compared with 66 healthy controls subject. Patients with LT were compared with patients who had EC. The children with Fontan circulation showed a significantly reduced HRV including total power (P < 0.0001), VLF (P < 0.0001), LF (P < 0.0001), and HF (P = 0.001) compared with the control subjects. The LT and EC patients did not differ significantly. Reduced HRV was found in both the LT and EC patients. In terms of HRV reduction, EC was not superior to LT.
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| 5. |
- Alenius Dahlqvist, Jenny, 1972-, et al.
(författare)
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Pacemaker treatment after Fontan surgery-A Swedish national study
- 2019
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Ingår i: Congenital Heart Disease. - : Computers, Materials and Continua (Tech Science Press). - 1747-079X .- 1747-0803. ; 14:4, s. 582-589
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveFontan surgery is performed in children with univentricular heart defects. Previous data regarding permanent pacemaker implantation frequency and indications in Fontan patients are limited and conflicting. We examined the prevalence of and risk factors for pacemaker treatment in a consecutive national cohort of patients after Fontan surgery in Sweden. MethodsWe retrospectively reviewed all Swedish patients who underwent Fontan surgery from 1982 to 2017 (n=599). ResultsAfter a mean follow-up of 12.2years, 13% (78/599) of the patients with Fontan circulation had received pacemakers. Patients operated with the extracardiac conduit (EC) type of total cavopulmonary connection had a significantly lower prevalence of pacemaker implantation (6%) than patients with lateral tunnel (LT; 17%). Mortality did not differ between patients with (8%) and without pacemaker (5%). The most common pacemaker indication was sinus node dysfunction (SND) (64%). Pacemaker implantation due to SND was less common among patients with EC. Pacemaker implantation was significantly more common in patients with mitral atresia (MA; 44%), double outlet right ventricle (DORV; 24%) and double inlet left ventricle (DILV; 20%). In contrast, patients with pulmonary atresia with intact ventricular septum and hypoplastic left heart syndrome were significantly less likely to receive a pacemaker (3% and 6%, respectively). ConclusionsThirteen percent of Fontan patients received a permanent pacemaker, most frequently due to SND. EC was associated with a significantly lower prevalence of pacemaker than LT. Permanent pacemaker was more common in patients with MA, DORV, and DILV.
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| 6. |
- Alenius Dahlqvist, Jenny, 1972-, et al.
(författare)
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Sinus node dysfunction in patients with Fontan circulation: could heart rate variability be a predictor for pacemaker implantation?
- 2019
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Ingår i: Pediatric Cardiology. - : Springer Science and Business Media LLC. - 0172-0643 .- 1432-1971. ; 40:4, s. 685-693
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Tidskriftsartikel (refereegranskat)abstract
- Sinus node dysfunction (SND) causes significant morbidity in patients after Fontan surgery. Heart rate variability (HRV) reflects the autonomic regulation of the heart, and changes in HRV have been associated with SND in adults. We aimed to study whether changes in HRV could be detected in 24-h electrocardiographic (ECG) recordings in Fontan patients with SND. We compared HRV results from two patient groups; patients with Fontan circulation who later required a pacemaker due to severe SND (n = 12) and patients with Fontan circulation and SND, without indication for pacemaker treatment (n = 11), with two control groups; patients with Fontan circulation without SND (n = 90) and healthy controls (n = 66). The Poincare plot index SD2 (representing changes in heart rate over 24-h) and the very low-frequency (VLF) HRV component were significantly higher in both SND groups, both compared with healthy controls and patients with Fontan circulation without SND. In SND patients with pacemakers, SD2 and VLF were slightly reduced compared to SND patients without pacemaker (p = 0.06). In conclusion, in Fontan patients with SND the HRV is significantly higher compared to healthy controls and Fontan patients without SND. However, in patients with severe SND requiring pacemaker, SD2 and VLF tended to be lower than in patients with SND without pacemaker, which could indicate a reduced diurnal HRV in addition to the severe bradycardia. This is a small study, but our results indicate that HRV analysis might be a useful method in the follow-up of Fontan patients regarding development of SND.
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| 7. |
- Andersson, Kennet, et al.
(författare)
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Directed coherence analysis in patients with severe autonomic dysfunction
- 2014
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Ingår i: 2014 8th conference of the European Study Group on Cardiovascular Oscillations (ESGCO). - : IEEE conference proceedings. ; , s. 167-168
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Konferensbidrag (refereegranskat)abstract
- Many different approaches have been applied to analyse the coupling between cardiovascular signals. This study evaluated the use of directed coherence, based on multivariate autoregressive modelling, for analysis of cardiovascular signals in patients with transthyretin amyloidosis, a rare disease where severe autonomic dysfunction is common.
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| 8. |
- Erelund, Sofia, et al.
(författare)
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Heart rate variability and cardiovascular risk factors in patients with rheumatoid arthritis : a longitudinal study
- 2023
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Ingår i: Autonomic Neuroscience. - : Elsevier. - 1566-0702 .- 1872-7484. ; 249
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Tidskriftsartikel (refereegranskat)abstract
- Background: It is established that the risk of cardiovascular disease (CVD) is increased in patients with Rheumatoid Arthritis (RA). Heart rate variability (HRV) is a method for evaluating the activity in the cardiac autonomic nervous system. Our aim was to assess the longitudinal development of HRV in patients with RA and compare with healthy controls. Furthermore, we wanted to investigate associations between HRV, inflammatory disease activity and cardiovascular complications in patients with RA over time.Method: HRV was assessed with frequency-domain analysis at baseline and after five years in 50 patients with early RA, all being younger than 60 years. HRV indices were age-adjusted based on the estimated age-dependency in 100 age and sex matched healthy controls. Additionally, clinical data including serological markers, disease activity, and blood pressure were collected from the patients. Eleven years after inclusion CVD was assessed.Results: At baseline, patients with RA presented with lower HRV compared to controls during deep breathing (6 breaths/min), paced normal breathing (12 breaths/min) and after passive tilt to the upright position. No significant change in HRV was observed at the five-year follow-up. A significant negative correlation was found between HRV parameters and systolic blood pressure (SBP) at baseline. A significant positive correlation was found between heart rate and inflammatory markers at baseline but not after five years. Nine patients had developed CVD after 11 years, but no significant association was found with baseline HRV data.Conclusion: This study showed that patients with RA have autonomic imbalance both at an early stage of the disease and after five years, despite anti-rheumatic medication, but no correlation between HRV and inflammation markers were observed. Reduced HRV was also significantly negatively correlated with increased SBP. Hypertension is a common finding in patients with RA. Thus, significant decline of HRV could be a useful early marker for development of hypertension in patients with RA.
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| 9. |
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| 10. |
- Granfeldt, Hans, et al.
(författare)
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Risk Factor Analysis of Swedish Left Ventricular Assist Device (LVAD) Patients
- 2003
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Ingår i: Annals of Thoracic Surgery. - : Elsevier. - 0003-4975 .- 1552-6259. ; 76:6, s. 1993-1998
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Tidskriftsartikel (refereegranskat)abstract
- Background. The use of left ventricular assist devices (LVADs) is established as a bridge to heart transplantation. Methods. All Swedish patients on the waiting list for heart transplantation, treated with LVAD since 1993 were retrospectively collected into a database and analyzed in regards to risk factors for mortality and morbidity. Results. Fifty-nine patients (46 men) with a median age of 49 years (range, 14 to 69 years), Higgins score median of 9 (range, 3 to 15), EuroScore median of 10 (range, 5 to 17) were investigated. Dominating diagnoses were dilated cardiomyopathy in 61% (n = 36) and ischemic cardiomyopathy in 18.6% (n = 11). The patients were supported with LVAD for a median time of 99.5 days (range, 1 to 873 days). Forty-five (76%) patients received transplants, and 3 (5.1%) patients were weaned from the device. Eleven patients (18.6%) died during LVAD treatment. Risk factor analysis for mortality before heart transplantation showed significance for a high total amount of autologous blood transfusions (p < 0.001), days on mechanical ventilation postoperatively (p < 0.001), prolonged postoperative intensive care unit stay (p = 0.007), and high central venous pressure 24 hours postoperatively and at the final measurement (p = 0.03 and 0.01, respectively). Mortality with LVAD treatment was 18.6% (n = 11). High C-reactive protein (p = 0.001), low mean arterial pressure (p = 0.03), and high cardiac index (p = 0.03) preoperatively were risk factors for development of right ventricular failure during LVAD treatment. Conclusions. The Swedish experience with LVAD as a bridge to heart transplantation was retrospectively collected into a database. This included data from transplant and nontransplant centers. Figures of mortality and morbidity in the database were comparable to international experience. Specific risk factors were difficult to define retrospectively as a result of different protocols for follow-up among participating centers. © 2003 by The Society of Thoracic Surgeons.
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