| 1. |
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| 2. |
- Carlson, Jonas, et al.
(författare)
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Can Orthogonal Lead Indicators of Propensity to Atrial Fibrillation be Accurately Assessed from the 12-Lead ECG?
- 2005
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 7:Suppl 2, s. 39-48
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Tidskriftsartikel (refereegranskat)abstract
- Aims: When analyzing P-wave morphology, the vectorcardiogram(VCG) has been shown useful to identify indicators of propensity to atrial fibrillation (AF). Since VCG is rarely used in the clinical routine, we wanted to investigate if these indicators could be accurately determined in VCG derived from standard 12-lead ECG (dVCG).Methods: ECG and VCG recordings from 21 healthy subjects and 20 patients with a history of AF were studied. dVCG was calculated from ECG using the inverse Dower transform. Following signal averaging of P-waves, comparisons were madebetween VCG and dVCG, where three parameters characterizing signal shape and 15 parameters describing the P-wave morphology were used to assess the compatibility of the two recording techniques. The latter parameters were alsoused to compare the healthy and the AF groups.Results: After transformation, P-wave shape was convincingly preserved. P-wave morphology parameters were consistent within the respective groups when comparing VCG and dVCG, with better preservation observed in the healthy group.Conclusion VCG derived from routine 12-lead ECG may be a useful alternate method for studying orthogonal P-wave morphology.
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| 3. |
- Carlson, Jonas, et al.
(författare)
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Classification of Electrocardiographic P-wave Morphology
- 2001
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2531 .- 0018-9294. ; 48:4, s. 401-405
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Tidskriftsartikel (refereegranskat)abstract
- The atrial activity of the human heart is normally visible in the electrocardiogram as a P-wave. In patients with intermittent atrial fibrillation, a different P-wave morphology can sometimes be seen, indicating atrial conduction defects. The purpose of this study was to develop a method to discriminate between such P-waves and normal ones. 20 recordings of each type were used in a classification which, based on impulse response analysis of the P-wave and linear discrimination between various parameters, produced a correct classification in 37 of the 40 recordings (sensitivity 95%, specificity 90%)
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| 4. |
- Carlson, Jonas, et al.
(författare)
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Classification of Electrocardiographic P-wave Morphology
- 2000
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Ingår i: Proceedings of the 39th IEEE Conference on Decision and Control, 2000.. - 0780366387 ; 2, s. 1804-1809
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The atrial activity of the human heart is normally visible in the ECG as a P-wave. In patients with intermittent atrial fibrilation, a different P-wave morphology can sometimes be seen, indicating atrial conduction defects. The purpose of this study was to develop a method to discriminate between such P-waves and normal ones. 20 recordings of each type were used in a classification which, based on impulse response analysis of the P-wave and linear discrimination between various parameters, produced a correct classification in 37 of the 40 recordings (sensitivity 95%, specificity 90%)
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| 5. |
- Carlson, Jonas, et al.
(författare)
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Left Atrial Conduction along the Coronary Sinus during Ectopic Atrial Tachycardia and Atrial Fibrillation: A Study Using Correlation Function Analysis
- 2003
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Ingår i: Journal of Cardiovascular Electrophysiology. - : Wiley. - 1540-8167 .- 1045-3873. ; 14:10 Suppl, s. 148-153
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Tidskriftsartikel (refereegranskat)abstract
- ntroduction: Correlation function analysis was applied to endocardial electrograms to investigate conduction patterns along the coronary sinus (CS) during sinus rhythm (SR) and atrial tachycardias. Methods and Results: Eighteen recordings were obtained from 14 patients suffering from supraventricular tachycardias. Five atrial fibrillation(AF) recordings were compared to 10 SR recordings and 3 ectopic atrial tachycardia (EAT) recordings. The maximum correlation coefficient was used to assess similarity between signals, i.e., if they originate from the samewavefront. The cumulative time delay, calculated as pairwise summation of interelectrode time delays was used as an indicator of activation sequence along CS. Method validation using SR showed right to left conduction with high correlations in 8 of 10 recordings indicating one single wavefront. EAT recordings showed consistent left to right conduction with left atrial foci and right to left with right atrial focus and lower correlations than SR. All 5 AFrecordings showed predominantly left to right conduction direction, also with correlations lower than SR.Conclusion: 1) Correlation function analysis can be used to assess agreement between signals and direction of activation spread. 2) Due to the position of CS, the results can be used to derive mechanisms of interatrial conduction. 3) Consistency in electrical activity propagation along CS iscommon in AF.
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| 6. |
- Hansson, Anders P, et al.
(författare)
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Right atrial free wall conduction velocity and degree of anisotropy in patients with stable sinus rhythm studied during open heart surgery
- 1998
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 1522-9645 .- 0195-668X. ; 19:2, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Although the perpetuation of several supraventricular arrhythmias is critically dependent upon intra-atrial conduction, the literature lacks detailed information on normal values of conduction velocity and degree of anisotropy. In order to explore these factors further, we have measured conduction velocities at the right atrial free wall during sinus rhythm and during atrial pacing in four directions parallel and perpendicular to the atrioventricular groove in patients with normal atria and stable sinus rhythm. METHODS AND RESULTS: Using a Bard Cardiac Mapping System, atrial ECGs were recorded using a 3 x 4 cm electrode array with 56 equally spaced bipolar electrodes in 12 patients undergoing open heart surgery due to ischaemic heart disease or Wolf-Parkinson-White syndrome. A bipolar pen probe connected to a Medtronic 5328 stimulator was used for pacing at a 10% higher rate than sinus rhythm. The local activation times were manually set and isochronal activation maps were created for each recording. The conduction velocities were calculated from the activation maps over a distance ranging from 2.2 to 4.2 cm. The majority of the activation maps showed no signs of anisotropy; the others had less than 15% spatial inhomogeneity of conduction. Mean conduction velocity, calculated from five consecutive beats, was 88 +/- 9 cm.s-1 (mean +/- SD), ranging between 68 +/- 4 and 103 +/- 3 cm.s-1 during sinus rhythm. Mean conduction velocity during atrial pacing was 81 +/- 16 cm.s-1 at a propagation direction of 0 degree, 74 +/- 14 cm.s-1 at a 90 degrees direction, 79 +/- 12 cm.s-1 at 180 degrees and 78 +/- 20 cm.s-1 at 270 degrees, where 0 degree was parallel to the atrioventricular groove in the cranial direction and the angle increased counter-clockwise. Mean conduction velocity during sinus rhythm was significantly higher (P < 0.05) than during atrial pacing at the 90 degrees and 180 degrees directions but not compared to atrial pacing at 0 degree or 270 degrees. There was no significant difference in mean conduction velocity in different directions during atrial pacing. CONCLUSION: Although anisotropy was documented during conduction velocity in individual cases, conduction velocity was not dependent on propagation direction at the epicardial right atrial free wall in patients with stable sinus rhythm. These findings do not exclude the presence of internodal preferential pathways as these are located sub-epicardially and a marked transmural discordance in activation has previously been documented in the vicinity of such pathways.
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| 7. |
- Herreros, Alberto, et al.
(författare)
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An Algorithm for Phase-Space Detection of the P Characteristic Points
- 2007
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Ingår i: PROC. annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC2007). Lyon, France, Aug 23-26, 2007. - 1557-170X. ; 1, s. 2004-2007
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Konferensbidrag (refereegranskat)abstract
- A new algorithm, based on embedding phase space, to detect the P-wave characteristic points of an ECG signal is reported in this paper. The multi-lead ECG is transformed into points of an embedding phase space where similar ECG morphologies are converted into phase space points that are close using some distance measure. The algorithm is robust with respect to the type of selected characteristic points (onset, peak and end), morphology changes, baseline oscillations and high frequency noise. The performance of the algorithm has been succesfully validated using both simulated and real ECG signals.
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| 8. |
- Herreros, Alberto, et al.
(författare)
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Analysis of Changes in the Beat-to-Beat P-wave Morphology Using Clustering Techniques
- 2009
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Ingår i: Biomedical Signal Processing and Control. - : Elsevier BV. - 1746-8094. ; 4:4, s. 309-316
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Tidskriftsartikel (refereegranskat)abstract
- Several pathologies related to the atrial electrical activity can be detected in the electrocardiogram P-wave. A protocol for analyzing P-wave morphology changes has been developed in this article. By using this protocol a study on the beat-to-beat P-wave morphology changes of 89 ECG signals is performed. An algorithmbased on the embedding space techniques has been used to extract the P-wave information of the ECG. The P-waves obtained in several of these ECGs exhibit significant alternate morphology changes. The morphologies have been classified by using the K-means clustering algorithm. The mechanism behind the P-wave morphology change process and its possible pathophysiological importance remains to be clarified.
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| 9. |
- Herreros, Alberto, et al.
(författare)
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Analysis of Changes in the Beat-to-Beat P-Wave Morphology Using Clustering Techniques
- 2008
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Ingår i: Proceedings of the 17th World Congress Proceedings of the 17th World Congress of The International Federation of Automatic Control. - 1474-6670. - 9783902661005 ; 41:1, s. 5215-5220
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Konferensbidrag (refereegranskat)abstract
- Several pathologies related to the atrial electrical activity can be detected in the electrocardiogram P-wave. A study on the beat-to-beat P-wave morphology changes of 89 ECG signals is performed in this article. An algorithm based on the embedding space techniques has been used to extract the P-wave information of the ECG. The P-waves obtained in several of these ECGs exhibit intermittent morphology changes. The morphologies have been classified by using the K-means clustering algorithm. The mechanism behind different P-wave morphologies and its possible pathophysiological importance remains to be clarified.
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| 10. |
- Holm, M., et al.
(författare)
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A New Method for Analysis of Atrial Activation during Chronic Atrial Fibrillation in Man
- 1996
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Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2531 .- 0018-9294. ; 43:2, s. 198-210
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Tidskriftsartikel (refereegranskat)abstract
- To further clarify the mechanisms maintaining chronic atrial fibrillation (CAF), a method identifying preferable activation patterns of the atria during fibrillation, by time averaging of multiple discrete excitation vectors, was developed. Repeated recordings, each of 56 atrial bipolar electrograms simultaneously acquired during 8 s, were made at multiple sites in the right atrial free wall and the left atrial appendage in 16 patients with CAF using a 2.17/spl times/3.54 cm electrode array. The local activation times (LAT's) in each recording were estimated as the median activation time at the respective measurement point. By calculating the time difference between the LAT's at adjacent measurement points in two spatial dimensions, a direction vector was created for each activation wave passing each set of measurement points, a total of 42 sets. By time averaging of the individual direction vectors (typically n=55) at each set of measurement points, preferable activation patterns were determined. Three types of activation patterns were found: 1) inconsistent activation (n=5), 2) consistent activation with preferential propagation directions (n=7) and 3) consistent activation with impulses originating from a localizable site within the recording area (n=4). All activation patterns were reproducible and the two latter patterns were proven significant using statistical tests. It is concluded that this new method is useful in further clarification of the mechanisms involved in the maintenance of atrial fibrillation.
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