| 1. |
- Bollmann, Andreas, et al.
(författare)
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Atrial fibrillatory rate and risk of left atrial thrombus in atrial fibrillation.
- 2007
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 9:8, s. 6-621
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Tidskriftsartikel (refereegranskat)abstract
- ims In atrial fibrillation (AF), a relation between electrocardiogram (ECG) fibrillatory wave amplitude and thrombus formation has been sought for long with conflicting results. In contrast, the possible relation between atrial fibrillatory rate obtained from the surface ECG and left atrial thrombus formation in patients with AF is unknown and was consequently evaluated in this study. Methods and results One-hundred and twenty-five patients (mean age 64 ± 12 years, 72% male) with persistent non-valvular AF (mean duration 28 ± 80 days) undergoing transesophageal echocardiography were studied. In all patients, standard 12-lead ECG recordings were acquired before the examination. Atrial fibrillatory rate was determined using spatiotemporal QRST cancellation and time–frequency analysis of lead V1. Atrial fibrillatory rate measured 401 ± 63 fibrillations per minute (fpm, range 235–566 fpm) and was related with age (R = −0.326, P < 0.001), ventricular rate (R = −0.202, P = 0.024), gender (407 ± 62 in males vs. 387 ± 64 fpm in females, P = 0.038) but not AF duration (R = 0.088, P = 0.374), presence of lone AF (408 ± 66 vs. 394 ± 58 fpm, P = 0.228), or beta-blocker or calcium channel blocker treatment (398 ± 63 vs. 405 ± 62 fpm, P = 0.556). Age was the only independent predictor of fibrillatory rate (B = −1.714, P < 0.001). In patients with left atrial thrombus (n = 10), spontaneous echo contrast (SEC) was more frequently present (70 vs. 29 %, p = 0.007) and left atrial appendage (LAA) outflow velocity was lower (26 ± 20 vs. 37 ± 15 cm/s, P = 0.012) than in patients without thrombus (n = 115). In contrast, mean fibrillatory rate, which showed a weak inverse correlation with LAA velocity (R = −0.118, P = 0.048) was not different between both groups (380 ± 56 vs. 403 ± 63 fpm, P = 0.226). Similarly, presence of thrombus and SEC combined was not related with fibrillatory rate. Conclusion Atrial fibrillatory rate obtained from surface ECG lead V1 is not a risk marker for left atrial thrombus formation in AF.
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| 2. |
- Carlson, Jonas, et al.
(författare)
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Non-invasive assessment of direction of right atrial activation during atrial fibrillation using correlation function analysis.
- 2007
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Ingår i: Computers in Cardiology. - 0276-6574. ; 34, s. 277-280
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Tidskriftsartikel (refereegranskat)abstract
- ECGs were recorded from three electrodes attached at the corners of an equilateral triangle positioned around the location of electrode V1. The atrial signal between QRST complexes was subjected to correlation function analysis to reveal differences in activation times between the electrode sites. The time differences found were used to calculate the direction of activation across the body surface. Twenty-three subjects were studied during sinus rhythm (SR), intraoperatively confirmed typical and reverse typical atrial flutter, or during paroxysmal or permanent atrial fibrillation (AF). Subjects studied during SR and patients with typical atrial flutter exhibited a uniform direction of activation, with the main vector pointing downwards. The propagation of atrial activation during permanent AF did not show a consistent direction, while patients with paroxysmal AF exhibited more uniform activation vectors, corresponding to the direction observed in patients with atrial flutter.
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| 3. |
- Havmöller, Rasmus, et al.
(författare)
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Age-related changes in P wave morphology in healthy subjects.
- 2007
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 7:22
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Tidskriftsartikel (refereegranskat)abstract
- Background We have previously documented significant differences in orthogonal P wave morphology between patients with and without paroxysmal atrial fibrillation (PAF). However, there exists little data concerning normal P wave morphology. This study was aimed at exploring orthogonal P wave morphology and its variations in healthy subjects. Methods 120 healthy volunteers were included, evenly distributed in decades from 20–80 years of age; 60 men (age 50+/-17) and 60 women (50+/-16). Six-minute long 12-lead ECG registrations were acquired and transformed into orthogonal leads. Using a previously described P wave triggered P wave signal averaging method we were able to compare similarities and differences in P wave morphologies. Results Orthogonal P wave morphology in healthy individuals was predominately positive in Leads X and Y. In Lead Z, one third had negative morphology and two-thirds a biphasic one with a transition from negative to positive. The latter P wave morphology type was significantly more common after the age of 50 (P < 0.01). P wave duration (PWD) increased with age being slightly longer in subjects older than 50 (121+/-13 ms vs. 128+/-12 ms, P < 0.005). Minimal intraindividual variation of P wave morphology was observed. Conclusion Changes of signal averaged orthogonal P wave morphology (biphasic signal in Lead Z), earlier reported in PAF patients, are common in healthy subjects and appear predominantly after the age of 50. Subtle age-related prolongation of PWD is unlikely to be sufficient as a sole explanation of this finding that is thought to represent interatrial conduction disturbances. To serve as future reference, P wave morphology parameters of the healthy subjects are provided.
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| 4. |
- Havmöller, Rasmus, et al.
(författare)
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Evolution of P-wave morphology in healthy individuals: a 3-year follow-up study.
- 2009
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 14:3, s. 226-233
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Orthogonal P-wave morphology in healthy men and women has been described using unfiltered signal-averaged technique and holds information on interatrial conduction. The stability of P-wave morphology in healthy subjects over time is not fully known. METHODS: Sixty-seven healthy volunteers were investigated (29 males, aged 63 +/- 14 years, 48 females, 60 +/- 13 years). Orthogonal lead data (X, Y, and Z) were derived from standard 12-lead ECGs (recording length 6 minutes, sampling rate 1kHz, resolution 0.625 muV) recorded at baseline (BL), and 3 years later at follow-up (FU). P waves were then signal-averaged and analyzed regarding P-wave morphology, locations of maxima, minima, zero-crossings, and P-wave duration (PWD). RESULTS: No differences of P-wave variables were observed at FU compared to BL, including PWD (127 +/- 12 vs 125 +/- 14 ms at BL and FU, respectively, n.s.). In 59 of the 67 subjects (88%), the P-wave morphology was unaltered at FU. However, in the remaining eight cases a distinctively different morphology was observed. The most common change (P=0.030) was from negative polarity to biphasic (-/+) in Lead Z (n=5). In one case the opposite change was observed and in two cases transition into advanced interatrial block morphology was evident at FU. CONCLUSIONS: In the majority of healthy subjects, P-wave morphology is stable at 3-year FU. Subtle morphological changes, observed principally in Lead Z, suggest variation of interatrial conduction. These changes could not be detected by measuring conventional PWD that remained unchanged in the total population.
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| 5. |
- Holmqvist, Fredrik, et al.
(författare)
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Altered interatrial conduction detected in MADIT II patients bound to develop atrial fibrillation.
- 2009
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 14:3, s. 268-275
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Changes in P-wave morphology have recently been shown to be associated with interatrial conduction route used, without noticeable changes of P-wave duration. This study aimed at exploring the association between P-wave morphology and future atrial fibrillation (AF) development in the Multicenter Automatic Defibrillator Trial II (MADIT II) population. METHODS: Patients included in MADIT-II without a history of AF with sinus rhythm at baseline who developed AF during the study ("Pre-AF") were compared to matched controls without AF development ("No-AF"). Patients were followed for a mean of 20 months. A 10-minute high-resolution bipolar ECG recording was obtained at baseline. Signal-averaged P waves were analyzed to determine orthogonal P-wave morphology, P-wave duration, and RMS20. The P-wave morphology was subsequently classified into one of three predefined types using an automated algorithm. RESULTS: Thirty patients (age 68 +/- 7 years) who developed AF during MADIT-II were compared with 60 patients (age 68 +/- 8 years) who did not. P-wave duration and RMS20 in the Pre-AF group was not significantly different from the No-AF group (143 +/- 21 vs 139 +/- 30 ms, P=0.26, and 2.0 +/- 1.3 vs 2.1 +/- 1.0 muV, P=0.90). The distribution of P-wave morphologies was shifted away from Type 1 in the Pre-AF group when compared to the No-AF group (Type 1/2/3/atypical; 25/60/0/15% vs 10/63/10/17%, P=0.04). CONCLUSIONS: This study is the first to describe changes in P-wave morphology in patients prior to AF development. The results indicate that abnormal interatrial conduction may play a role in AF development in patients with prior myocardial infarction and congestive heart failure.
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| 6. |
- Holmqvist, Fredrik, et al.
(författare)
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Atrial fibrillation signal organization predicts sinus rhythm maintenance in patients undergoing cardioversion of atrial fibrillation.
- 2006
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 8:8, s. 559-565
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Tidskriftsartikel (refereegranskat)abstract
- Electrical remodelling is believed to influence the outcome following cardioversion of patients with persistent atrial fibrillation (AF). However, the results in clinical studies are conflicting. We assessed the hypothesis that non-invasively obtained atrial fibrillatory organization can be used as a predictor of sinus rhythm (SR) maintenance. METHODS AND RESULTS: Fifty-four patients (37 men, age 67+/-11) with persistent AF (median duration 3 months, 1 day to 18 months), without anti-arrhythmic drug treatment, referred for cardioversion were studied. Assessment of the atrial harmonic decay was made by time-frequency analysis of the ECG. At 1-month follow-up, 30 patients had relapsed into AF. The mean harmonic decay at inclusion of those relapsing into AF was 1.5+/-0.3 compared with 1.1+/-0.3 among those maintaining SR (P=0.0004). Using a cut-off value of harmonic decay
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| 7. |
- Holmqvist, Fredrik, et al.
(författare)
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Atrial fibrillatory rate and sinus rhythm maintenance in patients undergoing cardioversion of persistent atrial fibrillation.
- 2006
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 27:18, s. 2201-2207
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Tidskriftsartikel (refereegranskat)abstract
- The study set out to explore whether an index of atrial electrical electrophysiology can be used to predict atrial fibrillation (AF) relapse, and if the predictive properties differ as a result of arrhythmia duration. METHODS AND RESULTS: The study comprised 175 consecutive patients with persistent AF (median duration 94 days, range 2 to 1044) referred for cardioversion. Twenty-nine patients had arrhythmia duration under 30 days (median 5 days, range 2-26). Atrial fibrillatory rate (AFR) was estimated using a frequency power spectrum analysis of QRST-cancelled ECG. At 1-month follow-up, 56% of the patients had relapsed to AF. The pre-cardioversion mean AFR of those patients was 399+/-52 fibrillations per minute (fpm) compared with 363+/-63 fpm among patients maintaining SR (P<0.0001). In patients with short AF duration, the difference was even more pronounced (424+/-52 vs. 345+/-65 fpm, P<0.01). In this group, a finding of an AFR above the mean value of the study population predicted AF relapse with high accuracy. CONCLUSION: In patients undergoing cardioversion of persistent AF, AF relapse is predicted by a higher AFR. A stronger association is seen in patients with short arrhythmia duration, reflecting either rapid remodelling or pre-existing changes in those who relapse to AF.
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| 8. |
- Holmqvist, Fredrik
(författare)
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Characterisation of Atrial Electrophysiology with respect to Atrial Fibrillation - A Non-Invasive Approach
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atrial fibrillation (AF) is the most common form of cardiac arrhythmia encountered in clinical practice, accounting. Recent findings highlight the need for better characterisation of the arrhythmia in each patient, in order to improve patient treatment. The main objective of this work was to characterise atrial electrophysiology with respect to AF by means of non-invasively obtained data. Spectral analysis of QRST-cancelled ECG recorded during AF was used in Studies I-IV. The derived parameter, atrial fibrillatory rate (AFR), was used as an index of atrial refractoriness. Analysis of signal-averaged P waves was used in Study V when studying patients with hypertrophic cardiomyopathy (HCM) during sinus rhythm (SR). In Study I, patients with permanent AF were investigated using long-term ECG recordings. AFR was estimated once every hour. A lower fibrillatory rate was observed during night-time, indicating that the withdrawal of the sympathetic nervous system is affecting the atria more than the increased parasympathetic tone. In Study II, patients with permanent AF and third degree AV block treated with pacemaker were investigated. Baseline recordings were compared with recordings made during controlled respiration with and without preceding atropine injection. The results demonstrate that the atria are modulated by the parasympathetic nervous system during AF. In Studies III and IV, the possible clinical applications of AFR were investigated. In Study III, the correlation between AFR and parameters obtained from transoesophageal echocardiography was studied. Although a strong correlation was found between AFR and left atrial appendage outflow velocity, the correlation was not strong enough to allow predictions of the latter based on the former. In Study IV, it was found that the AFR in patients relapsing to AF following cardioversion was significantly higher than in patients maintaining SR. In patients with limited arrhythmia duration it is probable that AFR can be used as a clinical predictor of relapse probability. In Study V, it was shown that the interatrial conduction in the AF prone HCM population is different than in a healthy control population. The morphological changes in the P wave appear to be best explained by a higher prevalence of blocking of one or more of the interatrial conduction routes. The present work sheds further light on the characteristics of AF electrophysiology. It is also demonstrated that by applying non-invasive techniques, important information may be obtained that is likely to affect everyday AF treatment.
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| 9. |
- Holmqvist, Fredrik, et al.
(författare)
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Detailed ECG analysis of atrial repolarization in humans.
- 2009
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 14:1, s. 13-18
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Data on human atrial repolarization are scarce since the QRS complex normally obscures its ECG trace. In the present study, consecutive patients with third-degree AV block were studied to better describe the human Ta wave. METHODS AND RESULTS: Forty patients (mean age 75 years, 17 men) were included. All anti-arrhythmic drugs were discontinued before ECG recording. Standard 12-lead ECGs were recorded, transformed to orthogonal leads and studied using signal-averaged P wave analysis. The average P wave duration was 124 +/- 16 ms. The PTa duration was 449 +/- 55 ms (corrected PTa 512 +/- 60 ms) and the Ta duration (P wave end to Ta wave end) was 323 +/- 56 ms. The polarity of the Ta wave was opposite to that of the P wave in all leads. The Ta peaks were located at 196 +/- 55 ms in Lead Y, 216 +/- 50 ms in Lead X, and 335 +/- 92 in Lead Z. No correlation was found between P wave duration and Ta duration, or between Ta peak amplitude and Ta duration. The morphology of the Ta wave was similar regardless of the interatrial conduction. CONCLUSIONS: The Ta wave has the opposite polarity, and the duration is generally two to three times that, of the P wave. Although the Ta peak may occasionally be located in the PQ interval during normal AV conduction, it is unlikely that enough information can be obtained from analysis of this segment to differentiate normal from abnormal atrial repolarization. Hence, an algorithm for QRST cancellation during sinus rhythm is needed to further improve analysis.
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| 10. |
- Holmqvist, Fredrik, et al.
(författare)
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Indices of electrical and contractile remodeling during atrial fibrillation in man
- 2006
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Ingår i: PACE. - : Wiley. - 1540-8159. ; 29:5, s. 512-519
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Tidskriftsartikel (refereegranskat)abstract
- Atrial electrical and contractile remodeling have been demonstrated to coincide during atrial fibrillation (AF) in experimental studies. We explored whether electrical and contractile remodeling correlate in man and explored its clinical implications. METHODS: Forty-nine patients with persistent AF were studied. Electrical remodeling was assessed noninvasively using spectral analysis to estimate the average fibrillatory rate (AFR). Atrial contractility was assessed by transesophageal echocardiography (TEE) measurement of left atrial appendage outflow velocity (LAAOV). RESULTS: The AFR was 403+/-43 fibrillations per minute (fpm) and the LAAOV was 0.27+/-0.14 m/s. A significant correlation was found between AFR and LAAOV (r=-0.47, P=0.001). In patients with a LAAOV>or=0.25 m/s, the AFR was 387+/-48 fpm compared to 419+/-31 fpm among patients with LAAOV<0.25 m/s (P<0.01). CONCLUSIONS: This study demonstrates that indices of electrical and contractile remodeling are strongly correlated in persistent AF in man. The interindividual overlap, however, is too large to allow predictions of LAAOV based on fibrillatory frequency alone.
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| 11. |
- Holmqvist, Fredrik, et al.
(författare)
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Interatrial conduction can be accurately determined using standard 12-lead electrocardiography: validation of P-wave morphology using electroanatomic mapping in man.
- 2008
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Ingår i: Heart Rhythm. - : Elsevier BV. - 1547-5271. ; 5:3, s. 413-418
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Different P-wave morphologies during sinus rhythm as displayed on standard ECGs have been postulated to correspond to differences in interatrial conduction. OBJECTIVE: The purpose of this study was to evaluate the hypothesis by comparing P-wave morphologies using left atrial activation maps. METHODS: Twenty-eight patients (mean age 49 +/- 9 years) admitted for ablation of paroxysmal atrial fibrillation were studied. Electroanatomic mapping of left atrial activation was performed at baseline during sinus rhythm with simultaneous recording of standard 12-lead ECG. Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology. The morphology was subsequently classified into one of three predefined types. All analyses were blinded. RESULTS: The primary left atrial breakthrough site was the fossa ovalis in 8 patients, Bachmann bundle in 18, and coronary sinus in 2. Type 1 P-wave morphology was observed in 9 patients, type 2 in 17, and type 3 in 2. Seven of eight patients with fossa ovalis breakthrough had type 1 P-wave morphology, 16 of 18 patients with Bachmann bundle breakthrough had type 2 morphology, and both patients with coronary sinus breakthrough had type 3 P-wave morphology. Overall, P-wave morphology criteria correctly identified the site of left atrial breakthrough in 25 (89%) of 28 patients. CONCLUSION: In the vast majority of patients, P-wave morphology derived from standard 12-lead ECG can be used to correctly identify the left atrial breakthrough site and the corresponding route of interatrial conduction.
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| 12. |
- Holmqvist, Fredrik, et al.
(författare)
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Noninvasive evidence of shortened atrial refractoriness during sinus rhythm in patients with paroxysmal atrial fibrillation.
- 2009
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Ingår i: PACE. - : Wiley. - 1540-8159. ; 32:3, s. 302-307
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Shortening of the atrial refractory period is the key feature of atrial electrical remodeling during atrial fibrillation (AF). During sinus rhythm (SR), assessment of the atrial refractoriness is hampered by the fact that the atrial repolarization wave (Ta wave) is largely obscured by the following QRST complex. The purpose of this study was to study the Ta wave in subjects with paroxysmal AF during SR with third-degree atrioventricular (AV) block, and in matched controls. METHODS: Fifteen patients (mean age 70 +/- 10 years, five males) with paroxysmal AF undergoing AV-nodal ablation were studied. Fifteen age- and gender-matched subjects (mean age 71 +/- 9 years, five males) with third-degree AV block, without a history of heart disease, were used as controls. Standard 12-lead electrocardiograms (ECGs) were recorded and transformed to orthogonal leads and studied using P-wave signal averaging technique. RESULTS: The P to Ta interval was shorter (408 +/- 47 ms vs 451 +/- 53 ms, P = 0.017) and in Lead Y the Ta peak location was earlier (156 +/- 31 ms vs 187 +/- 34 ms, P = 0.002) in subjects with paroxysmal AF than in the controls. The P-wave duration (126 +/- 15 ms vs 129 +/- 17 ms, P = 0.59) and morphology was similar in AF patients and controls. CONCLUSIONS: In this study, the ECG signs of shorter atrial refractoriness associated with a history of AF are visualized for the first time during SR. The finding of the earlier location of the PTa peak in AF subjects implies that a possible indicator of increased arrhythmia susceptibility may be visible already in the unprocessed ECG.
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| 13. |
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| 14. |
- Holmqvist, Fredrik, et al.
(författare)
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Rapid fluctuations in atrial fibrillatory electrophysiology detected during controlled respiration.
- 2005
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Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 289:2, s. 754-760
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Tidskriftsartikel (refereegranskat)abstract
- Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we evaluated whether slow, controlled respiration causes cyclic fluctuations in the frequency of the fibrillating atria. Eight patients (four women; median age 63 yr, range 53–68 yr) with chronic atrial fibrillation (AF) and third-degree atrioventricular block treated by permanent pacemaker were studied. ECG was recorded during baseline rest, during 0.125-Hz frequency controlled respiration, and finally during controlled respiration after full vagal blockade. We calculated fibrillatory frequency using frequency analysis of the fibrillatory ECG for overlapping 2.5-s segments; spectral analysis of the resulting frequency trend was performed to determine the spectrum of variations of fibrillatory frequency. Normalized spectral power at respiration frequency increased significantly during controlled respiration from 1.4 (0.76–2.0) (median and range) at baseline to 2.7 (1.2–5.8) ( P = 0.01). After vagal blockade, the power at respiration frequency decreased to 1.2 (0.23–2.8) ( P = 0.01). Controlled respiration causes cyclic fluctuations in the AF frequency in patients with long-duration AF. This phenomenon seems to be related to parasympathetic modulations of the AF refractory period.
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| 15. |
- Holmqvist, Fredrik, et al.
(författare)
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Signal-averaged P wave analysis for delineation of interatrial conduction - Further validation of the method
- 2007
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 7:29
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT: BACKGROUND: The study was designed to investigate the effect of different measuring methodologies on the estimation of P wave duration. The recording length required to ensure reproducibility in unfiltered, signal-averaged P wave analysis was also investigated. An algorithm for automated classification was designed and its reproducibility of manual P wave morphology classification investigated. METHODS: Twelve-lead ECG recordings (1 kHz sampling frequency, 0.625 muV resolution) from 131 healthy subjects were used. Orthogonal leads were derived using the inverse Dower transform. Magnification (100 times), baseline filtering (0.5 Hz high-pass and 50 Hz bandstop filters), signal averaging (10 seconds) and bandpass filtering (40-250 Hz) were used to investigate the effect of methodology on the estimated P wave duration. Unfiltered, signal averaged P wave analysis was performed to determine the required recording length (6 minutes to 10 s) and the reproducibility of the P wave morphology classification procedure. Manual classification was carried out by two experts on two separate occasions each. The performance of the automated classification algorithm was evaluated using the joint decision of the two experts (i.e., the consensus of the two experts). RESULTS: The estimate of the P wave duration increased in each step as a result of magnification, baseline filtering and averaging (100 +/- 18 vs. 131 +/- 12 ms; P < 0.0001). The estimate of the duration of the bandpass-filtered P wave was dependent on the noise cut-off value: 119 +/- 15 ms (0.2 muV), 138 +/- 13 ms (0.1 muV) and 143 +/- 18 ms (0.05 muV). (P = 0.01 for all comparisons).The mean errors associated with the P wave morphology parameters were comparable in all segments analysed regardless of recording length (95% limits of agreement within 0 +/- 20% (mean +/- SD)). The results of the 6-min analyses were comparable to those obtained at the other recording lengths (6 min to 10 s).The intra-rater classification reproducibility was 96%, while the interrater reproducibility was 94%. The automated classification algorithm agreed with the manual classification in 90% of the cases. CONCLUSION: The methodology used has profound effects on the estimation of P wave duration, and the method used must therefore be validated before any inferences can be made about P wave duration. This has implications in the interpretation of multiple studies where P wave duration is assessed, and conclusions with respect to normal values are drawn.P wave morphology and duration assessed using unfiltered, signal-averaged P wave analysis have high reproducibility, which is unaffected by the length of the recording. In the present study, the performance of the proposed automated classification algorithm, providing total reproducibility, showed excellent agreement with manually defined P wave morphologies.
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| 16. |
- Holmqvist, Fredrik, et al.
(författare)
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Variable interatrial conduction illustrated in a hypertrophic cardiomyopathy population
- 2007
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Ingår i: Annals of Noninvasive Electrocardiology. - 1082-720X. ; 12:3, s. 227-236
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with hypertrophic cardiomyopathy (HCM) have a high incidence of atrial fibrillation. They also have a longer P-wave duration than healthy controls, indicating conduction alterations. Previous studies have demonstrated orthogonal P-wave morphology alterations in patients with paroxysmal atrial fibrillation. In the present study, the P-wave morphology of patients with HCM was compared with that of matched controls in order to explore the nature of the atrial conduction alterations. Methods and Results: A total of 65 patients (45 men, mean age 49 +/- 15) with HCM were included. The control population (n = 65) was age and gender matched (45 men, mean age 49 +/- 15). Five minutes of 12-lead ECG was recorded. The data were subsequently transformed to orthogonal lead data, and unfiltered signal-averaged P-wave analysis was performed. The P-wave duration was longer in the HCM patients compared to the controls (149 +/- 22 vs 130 +/- 16 ms, P < 0.0001). Examination of the P-wave morphology demonstrated changes in conduction patterns compatible with interatrial conduction block of varying severity in both groups, but a higher degree of interatrial block seen in the HCM population. These changes were most prominent in the Leads Y and Z. Conclusion: The present study suggests that the longer P-wave duration observed in HCM patients may be explained by a higher prevalence of block in one or more of the interatrial conduction routes.
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| 17. |
- Holmqvist, Marika, 1959-
(författare)
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Addressing Alcohol : Alcohol Prevention in Swedish Primary and Maternity Health Care and Occupational Health Services
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Alcohol consumption in Sweden has reached its highest levels of the past 100 years in the wake of the country’s entry into the European Union in 1995. Increased alcohol prevention efforts in Swedish health care settings have been given high priority by the authorities. The Swedish parliament’s national action plan up to 2010 emphasises that public health must be protected by achieving reductions in alcohol consumption and limiting the negative physical, psychological, and social effects of alcohol.This thesis aims to investigate various aspects related to the current alcoholpreventive activity in 2006 among health care professionals in three important health care settings: primary health care (PHC), occupational health services (OHS), and maternity health care (MHC). The thesis includes four studies based on a total population mail questionnaire survey.Results from the studies show that alcohol issues in both PHC and OHS were addressed less frequently than all other lifestyle issues, i.e. smoking, physical activity, overweight, and stress. Important barriers to alcohol-preventive activity in these settings were perceived lack of time, scepticism regarding the effectiveness of addressing the issue of alcohol, fear of potentially negative patient responses, uncertainty about how to ask, uncertainty about how to give advice regarding alcohol, and uncertainty concerning where to refer the patient.OHS professionals generally considered themselves more skilful than their PHC counterparts in achieving change in patients’ alcohol habits and more knowledgeable about providing advice to patients with risky alcohol consumption. The overall frequency of initiating discussions about alcohol with patients in PHC and OHS was positively associated with self-assessed skills, knowledge, and education for all professional categories.Slightly more than one-third of the MHC midwives used a questionnaire to assess the woman’s alcohol intake before the pregnancy; AUDIT was the most commonly used questionnaire. Their perceived knowledge concerning alcohol and pregnancy matters was generally high, but the midwives considered themselves less proficient at detecting pregnant women with risky alcohol consumption before the pregnancy.MHC midwives had participated in more continuing professional education in handling risky drinking than all other categories investigated. PHC nurses was the category that had the highest proportion of professionals who lacked education in handling risky drinking. Professionals in PHC, OHS, and MHC to a large extent believed that provision of more knowledge about counselling techniques to use when alcohol-related symptoms are evident could facilitate increased alcohol intervention activity.
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| 18. |
- Holmqvist, Marika, 1959-, et al.
(författare)
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Alcohol prevention activity in Swedish primary health care and occupational health services : Asking patients about their drinking
- 2008
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Ingår i: Nordic Studies on Alcohol and Drugs. ; 25:6, s. 489-504
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Tidskriftsartikel (refereegranskat)abstract
- Aims To investigate the alcohol preventive activity in Swedish Occupational health services (OHS) and Primary health care (PHC) in relation to education in handling risky drinking, perceived skills in achieving change in patients’ alcohol habits, and knowledge in alcohol issues among the physicians and nurses in these two settings. Design and Methods All Swedish physicians and nurses in OHS and PHC having the authority to issue prescriptions were surveyed with a postal questionnaire. The questionnaire was returned by 313 OHS physicians (response rate 54%), 759 OHS nurses (69%), 1821 PHC physicians (47%), and 3125 PHC nurses (55%). Regression analyses were used to assess the independent and interacting effects of skills, knowledge, education, sex, age, and years in practice, patient encounters per week, and location of unit. Results OHS professionals were more active in initiating discussions about alcohol with their patients than their colleagues in PHC. OHS professionals considered themselves more skilful and knowledgeable than PHC professionals. OHS nurses and PHC physicians were the professional categories that had received most education in handling risky drinking. Skills were positively associated with activity for all categories except OHS physicians. Knowledge and education were positively associated with activity for all categories except OHS nurses. Conclusions OHS professionals were more active than the PHC professionals in addressing alcohol issues with their patients. Education, knowledge, and skills were positively associated with activity for most professional categories in the two settings.
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| 19. |
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| 20. |
- Holmqvist, Marika, 1959-, et al.
(författare)
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Asking patients about their drinking - A national survey among primary health care physicians and nurses in Sweden
- 2008
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Ingår i: Addictive Behaviors. - : Elsevier BV. - 0306-4603. ; 33:2, s. 301-314
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Tidskriftsartikel (refereegranskat)abstract
- Aims To investigate the extent to which Swedish primary health care (PHC) general practitioners (GPs) and nurses discuss alcohol issues with their patients, their reasons for and against addressing alcohol issues, their perceived importance of these issues, and factors that could facilitate increased alcohol intervention activity among the PHC professionals. Methods All Swedish GPs and nurses who have the authority to issue prescriptions were surveyed with a postal questionnaire. The questionnaire was returned by 1821 GPs (47% response rate) and 3125 nurses (55% response rate). Results Fifty percent of the GPs and 28% of the nurses stated that they “frequently” discussed alcohol with their patients. The two most common reasons for asking patients about their drinking were that the GPs and nurses considered it part of their routines and the belief that the patient had alcohol-related symptoms. GPs said that improved opportunities for referral to specialists and provision of more knowledge about counselling techniques for use when alcohol-related symptoms are evident were the most important facilitators to increased intervention activity. Concerning the nurses, 93% stated that more time devoted to health-oriented work could facilitate increased alcohol intervention activity. Conclusions The findings highlight a considerable gap between the recognition of the significance of the alcohol problem and Swedish PHC intervention activity. Keywords: Primary health care; Alcohol intervention; Risk consumption
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| 21. |
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| 22. |
- Holmqvist, Marie E, et al.
(författare)
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No increased occurrence of ischemic heart disease prior to the onset of rheumatoid arthritis : results from two Swedish population-based rheumatoid arthritis cohorts.
- 2009
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 60:10, s. 2861-2869
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the relative importance of shared etiologies for rheumatoid arthritis (RA) and ischemic heart disease (IHD) in terms of the well-known increased risk of IHD in patients with RA, by assessing the occurrence of IHD up until the time of the onset of the first symptoms of RA. METHODS: We assessed the prevalence of a history of IHD, myocardial infarction (MI), and angina pectoris before the onset of RA symptoms in 2 large population-based case-control studies. Patients with newly diagnosed RA according to the criteria of the American College of Rheumatology were included as cases. We used data from the Swedish Early Arthritis Register study and the Swedish Epidemiologic Investigation of Rheumatoid Arthritis case-control study and from general population controls. Information on IHD, MI, and angina pectoris was obtained from the nationwide Hospital Discharge Register and from self reports. We calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) to compare the prevalence of a history of IHD/MI/angina pectoris among patients with RA with that among population controls. RESULTS: We could not detect any increased occurrence of IHD, MI, or angina pectoris before the onset of symptoms of RA, regardless of whether data on IHD were obtained from the Hospital Discharge Register or were self reported. As detected in the Hospital Discharge Register, the OR for IHD overall was 1.0 (95% CI 0.9-1.1), the OR for MI was 1.0 (95% CI 0.9-1.1), and the OR for angina pectoris was 1.0 (95% CI 0.9-1.2). CONCLUSION: Shared risk factors or susceptibilities for RA and IHD are likely to contribute less than RA-related factors to the increased occurrence of IHD in patients with manifest RA. Nonetheless, the existence of shared factors associated with longer latency until the occurrence of IHD cannot be excluded.
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| 23. |
- Larsson, David, et al.
(författare)
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The diagnostic and prognostic value of brain natriuretic peptides in adults with a systemic morphologically right ventricle or Fontan-type circulation.
- 2007
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273. ; 114:3, s. 345-351
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Tidskriftsartikel (refereegranskat)abstract
- Background: In acquired heart disease, brain natriuretic peptide (BNP) and N-Teminal pro-brain natriuretic peptide (NT-proBNP) are increasingly used as diagnostic and prognostic markers. In adult Congenital heart disease, the abnormal anatomy and physiology complicate assessment of cardiac function. We Studied the clinical correlates of measurement of natriuretic peptides (NP) in adults with a right ventricle in the systemic position or with Fontan-type physiology. Methods: A prospective longitudinal study (follow up time 23 +/- 13 months, mean +/- S.D.) was conducted in a specialised centre on 61 patients (age 26 +/- 8 years; NYHA class 1.5 +/- 0.6) including Senning/Mustard corrected transposition, congenitally corrected transposition and Fontan/ total cavopulmonary connection. Plasma NP concentration was compared with NYHA class, exercise capacity and echocardiographically determined systemic systolic ventricular function. Results: Neurohormone concentrations were generally elevated (mean=290% of upper reference limit) and related to NYHA class (P < 0.001, NYHA I vs. II-IV). No clinically significant relationship to ventricular function or exercise capacity was found however. An NP measurement could not predict the future Course of the disease in terms of functional status or ventricular function. Conclusion: In contrast to patients with acquired heart disease, measurement of NP seems to have low clinical value in adults with a right ventricle in the systemic position or with Fontan-type physiology.
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| 24. |
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| 25. |
- Platonov, Pyotr, et al.
(författare)
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Non-Invasive Estimates of Left Atrial Activation in a Patient with Dissociated Left Atrial Tachycardia following Ablation of Atrial Fibrillation
- 2009
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Ingår i: CINC: 2009 36TH Annual Computers In Cardiology Conference. - 0276-6574. - 9781424472819 ; , s. 133-136
-
Konferensbidrag (refereegranskat)abstract
- Introduction: Interatrial frequency gradient is used to guide catheter ablation of atrial fibrillation (AF) but reliable tools for its non-invasive estimation are lacking. We present a patient with dissociated left and right atrial rhythms that allows identification of sum face ECG leads that closely reflect left atrial activity. Methods: 12-lead ECG was recorded simultaneously with electrograms from the right and left atrial appendages (RAA/LAA). AF frequency spectra have been calculated from all 12 leads using spatiotemporal QRST cancellation and Welch periodogram. The dominating atrial cycle length (ACL) in the surface ECG leads was subsequently compared with ACL(LAA). Results: RAA and LAA cycle lengths were 1276 ins and 252 ins respectively. Of all surface ECG leads, AF frequency spectra in leads VI and aVR demonstrated the best agreement with ACL(LAA) showing prominent peaks corresponding to the LAA activation frequency. Conclusion: Leads VI and aVR contain a prominent left atrial component that has to be considered when interpreting fibrillatry activity from sum face ECG.
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| 26. |
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| 27. |
- Tapanainen, Jari M., et al.
(författare)
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Interatrial right-to-left conduction in patients with paroxysmal atrial fibrillation
- 2009
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Ingår i: Journal of Interventional Cardiac Electrophysiology. - : Springer Science and Business Media LLC. - 1572-8595 .- 1383-875X. ; 25:2, s. 117-122
-
Tidskriftsartikel (refereegranskat)abstract
- We wanted to illustrate the right-to-left impulse propagation routes during sinus in patients with paroxysmal atrial fibrillation (PAF), as alterations in conduction patterns have been linked to the pathogenesis of PAF, and as no large patient materials have been published. Patients underwent 3-D electroanatomical contact mapping prior to catheter ablation. The site of the earliest left atrial (LA) activation was determined. Three different interatrial routes were identified, either as solitary pathways (36/50 patients, 72%) or in their combinations (14/50). Bachmann's bundle (BB) was involved in the majority of the cases with solitary routes (25/36). More seldom, impulse propagation occurred near the oval fossa (FO) (7/36) or the coronary sinus ostium (4/36). In patients with combined routes, both the BB (10/14) and FO routes (11/14) were included in most cases. In PAF patients, LA can be activated during sinus rhythm through three distinct connections, either encompassing a single route or via any combination of these connections. In one third, the earliest LA activation occurs outside BB. The knowledge of the propagation patterns may give insight into the pathophysiology of PAF and into refining ablation therapy.
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| 28. |
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| 29. |
- Törneman, Niklas, et al.
(författare)
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Litteraturstudie om kemiska ämnen och nanopartiklar i produkter inför screening 2007
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- SWECO VIAK har på uppdrag av Naturvårdsverket genomfört en litteraturstudie av ett 80 tal ämnen som kan bli aktuella för screening inom den nationella miljöövervakningen. Dessutom har en litteraturstudie om nanopartiklar genomförts.Litteraturstudierna omfattade fysiokemisk information, begränsningar och förbud som berör ämnena, toxikologiska och ekotoxikologiska data, hantering och emissioner av ämnena, spridning och omvandling i naturen, förekomst i miljö och människa, en PBT bedömning (dvs. en bedömning av ämnenas motstånd mot nedbrytning, ämnenas bioackumulationspotential och ämnenas toxicitet), en bedömning av möjliga matriser där ämnena kan återfinnas samt möjliga metoder för analys av ämnena.För att förbättra överskådligheten presenteras detaljerad information om de olika ämnena i ämnesrapporter som bifogas huvudrapporten. I själva rapporten redovisas varje ämnesgrupp i översiktliga tabeller där en del av informationen om varje ämne återfinns.En rad olika informationskällor har använts. Dessa innefattar olika ämnesdatabaser, rapporter från statliga och överstatliga organ, vetenskapliga databaser där nyare information återfinns och olika tillverkares/importörers/exportörers information om de olika ämnena.De studerade ämnesgrupperna är, med en kortfattad beskrivning:Aminer är en grupp alifatiska eller aromatiska ämnen där minst en amingrupp ingår. Alla ämnen i gruppen är faroklassificerade och tillgången på toxikologiska och ekotoxikologisk data är förhållandevis god. Ämnena inom gruppen används bl.a. som smörjmedelstillsatser och tre ämnen i gruppen är högvolymsprodukter. Några av ämnena bedöms vara något intressanta för screening pga. de påträffats i miljön och kan ha negativa hälso- och miljöeffekter.Biocider är en liten grupp ämnen som bl.a. används i färger. Alla ämnena i gruppen är faroklassificerade som mycket giftiga för vattenlevande organismer och tillgången på toxikologiska och ekotoxikologisk data är förhållandevis god. Ett av ämnena i gruppen bedöms vara något intressant för screening pga. de förhållandevis låga ekotoxikologiska effekthalterna och den icke försumbara mängden som registreras.Estrar innefattar både estrar med enkla och polyaromatiska substituenter och alifatiska estrar. Två ämnen i gruppen är faroklassificerade som mycket giftiga för vattenlevande organismer och tillgången på ekotoxikologiska data är förhållandevis god. Ämnena ingår i olika industriella kemikalieprodukter och de flesta är högvolymskemikalier i EU. Två av ämnena i gruppen bedöms vara något intressanta för screening pga. de förhållandevis låga ekotoxikologiska effekthalterna och den icke försumbara mängden som registreras.Heterocykliska ämnen innefattar fyra ämnen vars enda strukturella likhet är att de innehåller minst en aromatisk ring. Flera ämnen i gruppen är faroklassificerade som mycket giftiga för vattenlevande organismer och tillgången på ekotoxikologisk data är begränsad. Ämnena ingår i olika industriella kemikalieprodukter och inga är högvolymskemikalier i EU. Ämnena i gruppen bedöms vara mindre intressanta för screening. Framförallt för att förhållandevis små mängder registreras årligen.Organiska fosfater och svavelföreningar innefattar tre ämnen utan strukturella likheter. Alla tre ämnen är högvolymsprodukter i EU och används som tillsatsämnen i kemikalie/plast -industrin. Ett av ämnena i gruppen är något intressant för screening eftersom registreringen ökar samtidigt som ämnet är misstänkt cancerframkallande. Dock är registreringen av detta ämne i Sverige förhållandevis låg (20 ton/år).Organiska halogener innefattar åtta ämnen. Samtliga är faroklassificerade som mycket giftiga för vattenlevande organismer och tillgången på ekotoxikologiska data är god. Fyra ämnen är dessutom misstänkt cancerogena. De flesta ämnen i gruppen är bekämpningsmedel och fyra ämnen är högvolymsprodukter. Flera ämnena i gruppen bedöms vara intressanta för screening pga. mycket hög giftighet gentemot vattenlevande organismer. Extra intressant i denna grupp är cypermetrin vars användning förväntas öka för att skydda timmerupplag mot skadedjurangrepp.Organiska jonföreningar innefattar sexton anjoniska ämnen som alla innehåller minst en bensenring. Flera av ämnena är alkylbensensulfonater och några av dessa har linjära alkylgrupper vilket innebär att de är s.k. linjära alkylbensensulfonater (LAS). Inga av ämnena i gruppen är faroklassificerade. Ämnen förekommer främst i olika rengörings- och ytbehandlingsprodukter och elva ämnen i gruppen är högvolymsprodukter i EU. Tillgången på ekotoxikologiska data är varierande men flera av ämnena tycks vara relativt giftiga för vattenlevande organismer. Flera ämnen i denna grupp bedöms vara intressanta för screening främst för att stora mängder registreras årligen samtidigt som den huvudsakliga användningen är i sådana produkter där en spridning till omgivningen via t.ex. reningsverk är möjlig.Pigmentämnen innefattar 10 gula, 3 orange, 13 röda, 3 lila, 1 blå och 2 gröna pigmentämnen. Hela gruppen är mycket heterogen vad gäller molekylstruktur, egenskaper, farlighet förr människa och miljö samt registrerade mängder. I denna studie är detta den grupp av ämnen som det finns minst information om i förhållande till den mängd som registreras. Trots bristen på information bör inte denna grupp uteslutas från screening. Däremot kan det viktigaste kriteriet för urval av pigmentämnen till screening tänkas vara den registrerade mängden. Ur detta hänseende framstår det enda blå pigmentämnet som en lämplig kandidat med en registrerad mängd av 1250 ton år 2004 samtidigt som det finns förhållandevis mycket information om detta ämne.Betongtillsatser innefattar 7 ämnen vars enda gemensamma nämnare är att de alla används som tillsatsämnen vid betongtillblandning. Flertalet av dessa ämnen är faroklassificeradeoch alla ämnen är högvolymsprodukter inom EU samtidigt som mycket stora mängder registreras i Sverige årligen (100 – 12000 ton). Tillgången på ekotoxikologisk data är varierande men flera av ämnena tycks vara relativt giftiga för vattenlevande organismer. Flera ämnen i denna grupp bedöms vara intressanta för screening främst för att mycket stora mängder registreras årligen samtidigt som deras miljöfarlighet inte är obetydlig.Nanopartiklar är inte en ämnesgrupp i egentlig mening. Istället är detta en materialkategori som kännetecknas av rymdstrukturer på en skala < 100 nm. I denna rapport behandlas främst nanopartiklar vilket innefattar både linjära och partikulära nanomaterial men inte nanoytor (ytbeläggningar). Nanopartiklar kemiska sammansättning varierar mellan helt oorganiska nanopartiklar, kolnanopartiklar och nanokompositer. Pga. av sin storlek kan nanopartiklar passera en rad biologiska barriärer inklusive cellmembran och blod-hjärn barriären. Nanopartiklars speciella egenskaperna (t.ex. hög reaktivitet) beror bl.a. på den extremt stora ytan i förhållande till volymen vilket innebär att en stor andel av alla atomer befinner sig på ytan av strukturer, där de har en större möjlighet till att interagera med andra abiotiska eller biologiska material. Nanopartiklar har i laboratorieförsök visat sig kunna ha negativa hälsoeffekter. Trots detta finns det endast begränsad kunskap om i vilken grad som exponering för nanopartiklar leder till faktiska hälsoeffekter. Det går inte i nuläget att kvantifiera varken import, export eller mängden nanopartiklar som används i Sverige. Orsakerna är att det i nuläget inte finns några krav på att material eller produkter som innehåller nanopartiklar skall rapporteras till någon myndighet, varken i Sverige eller på EU-nivå. Dessutom finns det en mycket lång rad användningsområden för nanopartiklar, vilket gör att det kan vara besvärligt att sammanställa statistik som på ett tillförlitligt sätt kvantifierar användning, export och import. Det faktum att mycket stora mängder nanopartiklar (framförallt kolpulverbaserade nanopartiklar) använts i en lång rad år före begreppet nanopartiklar uppmärksammades, försvårar statistiksammanställningen ytterligare.
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| 30. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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A New THOR Shoulder Design: A Comparison with Volunteers, the Hybrid III and THOR NT
- 2007
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 8:3, s. 211-222
-
Tidskriftsartikel (refereegranskat)abstract
- Objective Since the shoulders are rarely seriously injured in frontal or oblique collisions, they have been given low priority in the development of frontal impact crash test dummies. The shoulder complex geometry and its kinematics are of vital importance for the overall dummy kinematics. The shoulder complex also influences the risk of the safety belt slipping off the shoulder in oblique forward collisions. The first aim of this study was to develop a new 50th percentile male THOR shoulder design while the second was to compare the new shoulder, mounted on a THOR NT dummy, with volunteer, THOR NT and Hybrid III range-of-motion and stiffness data. The third aim was to test the repeatability of the new shoulder during dynamic testing and to see how the design behaves with respect to belt slippage in a 45° far-side collision.Methods The new 50th percentile THOR shoulder design was developed with the aid of a shell model of the seated University of Michigan Transportation Research Institute (UMTRI) 50th percentile male with coordinates for joints and bony landmarks (Schneider et al., 1983). The new shoulder design has human-like bony landmarks for the acromion and coracoid processes. The clavicle curvature and length are also made similar to that of a male human, as is the range-of-motion in the anterior-posterior, superior-inferior and medial-lateral directions. The new shoulder design was manufactured and tested under the same conditions that Törnvall et al. (2005b) used to compare the shoulder range-of-motion for the volunteers, Hybrid III and THOR Alpha. The new design was also tested in two dynamic test configurations: the first was a 0° full-frontal test and the second was a 45° far-side test. The dummy tests were conducted with an R-16 seat with a three-point belt, the ΔV was 27.0 ±0.5 km/h and the maximum peak acceleration was approximately 14.6 ±0.5 g for each test.Results A new shoulder design with geometry close to that of humans was developed to be retrofitted to the THOR NT dummy. The results showed that the range-of-motion for the new shoulder complex during static loading was larger by at least a factor of three, for the maximum load (200 N/arm), than that of either the Hybrid III or the THOR NT; this means it was more similar to the volunteers’ range-of-motion. It was observed that the THOR NT with the new shoulder did not slide out of the shoulder-belt during a far-side collision. The performance of the new shoulder was reasonably repeatable and stable during both the static tests and the sled tests.Conclusions A new shoulder for the THOR NT has been designed and developed, and data from static range-of-motion tests and sled tests indicate that the new shoulder complex has the potential to function in a more human-like manner on the THOR dummy.
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| 31. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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A New THOR Shoulder Design: Its Range-of-Motion in Comparison with Volunteers, the Hybrid III and THOR NT
- 2006
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Ingår i: International IRCOBI Conference on the Biomechanics of Impact. ; , s. 409-412
-
Konferensbidrag (refereegranskat)abstract
- There is a need for dummies that mimic crash victims kinematics in oblique and offset frontal collisions. Improved seatbelt-to-dummy interaction in crash testing is also desirable. Hence, a new THOR shoulder was developed and evaluated in comparison with volunteers, the Hybrid III and THOR NT shoulder range-of-motion. The new shoulder has human-like bony landmarks, clavicle curvature and length, and joints. The evaluation showed that the range-of-motion for the static loading of the new shoulder was similar to that of the volunteers. This was not so for the Hybrid III and THOR NT. The data indicates that the new shoulder design can provide more human-like shoulder motions in a crash test.
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| 32. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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Comparison of Shoulder Range-of-Motion and Stiffness between Volunteers, Hybrid III and THOR Alpha in Static Frontal Impact Loading
- 2005
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 10:2, s. 151-160
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the shoulder range-of-motion and stiffness between volunteers and 50th percentile dummies in static loading conditions simulating frontal collisions. Five volunteers a Hybrid III and a THOR Alpha were positioned in a test rig where both arms were statically loaded in the forward-upward direction at 90°, 135° and 170° angles while the sternum was supported. The distances between right shoulders and sternums were estimated by means of photo analysis. The photo analysis showed that the volunteers’ range-of-motion was at least three times larger for the maximum load (200 N/arm) than those of the Hybrid III and the THOR Alpha. The results indicate that the biofidelity of the dummies used today in full-frontal, oblique and offset frontal collisions may be improved by redesigned shoulder complexes. The dummies would then better predict the human kinematics and the loading of the chest by various restraint systems.
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| 33. |
- Törnvall, Fredrik, 1975, et al.
(författare)
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EVALUATION OF DUMMY SHOULDER KINEMATICS IN OBLIQUE FRONTAL COLLISIONS
- 2008
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Ingår i: IRCOBI. - 9783033015807 ; , s. 195-210
-
Konferensbidrag (refereegranskat)abstract
- The present study evaluates shoulder kinematics of the Hybrid III and THOR NT, with the firstversion of a new shoulder design (SD-1), in 45° far-side, full frontal and 30° near-side collisions. Intotal eleven dummy tests were conducted in the three collision angles, while film and instrument datawere generated and compared with those of PMHS data from Törnvall (2008). For the 45° far-sideimpact, the THOR SD-1NT dummy retained the shoulder belt on the shoulder during on-loading, as didthe PMHSs, whereas the THOR NT did not. In the 30° near-side impact,
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