| 1. |
- Alcaraz Martinez, Raul, et al.
(författare)
-
Application of frequency and sample entropy to discriminate long-term recordings of paroxysmal and persistent atrial fibrillation
- 2010
-
Ingår i: Engineering in Medicine and Biology Society (EMBC), 2010 Annual International Conference of the IEEE. - 1557-170X. - 9781424441235 ; , s. 4558-4561
-
Konferensbidrag (refereegranskat)abstract
- Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. At an early stage of the disease, AF may terminate spontaneously and is then referred to as paroxysmal AF. On the other hand, when external intervention is required for the arrhythmia to terminate, it is referred to as persistent AF. In this work, a method to discriminate between paroxysmal and persistent AF in the long-term ECGs is presented. The dominant frequency as well as the organization of the atrial activity are employed to characterize AF. The dominant atrial frequency (DAF) is estimated using hidden Markov model based frequency tracking, and organization is estimated by the sample entropy of the main atrial wave (MAW) and the first two harmonics, respectively. Long-term variations in DAF and organization from 50 ECG recordings were evaluated, showing that episodes of paroxysmal AF were consistently associated with lower DAF and organization of the MAW and the harmonics, than was persistent AF. Discrimination of paroxysmal and persistent AF resulted in classification rates of 84.1±26.1%, thus suggesting that it possible to discriminate between paroxysmal and persistent AF in patients without previously known AF history.
|
|
| 2. |
- Alcaraz Martinez, Raul, et al.
(författare)
-
Classification of paroxysmal and persistent atrial fibrillation in ambulatory ECG recordings
- 2011
-
Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 58, s. 1441-1449
-
Tidskriftsartikel (refereegranskat)abstract
- The problem of classifying short atrial fibrillatory segments in ambulatory ECG recordings as being either paroxysmal or persistent is addressed by investigating a robust approach to signal characterization. The method comprises preprocessing, estimation of the dominant atrial frequency for the purpose of controlling the subbands of a filter bank, and computation of the relative subband (harmonics) energy and the subband sample entropy. Using minimum-error-rate classification of different feature vectors, a dataset consisting of 24-h ambulatory recordings from 50 subjects with either paroxysmal (26) or persistent (24) atrial fibrillation (AF) was analyzed on a 10-s segment basis; a total of 212196 segments were classified. The best performance in terms of area under the receiver operating characteristic curve was obtained for a feature vector defined by the subband sample entropy of the dominant atrial frequency and the relative harmonics energy, resulting in a value of 0.923, whereas that of the dominant atrial frequency was equal to 0.826. It is concluded that paroxysmal and persistent AF can be discriminated from short segments with good accuracy at any time of an ambulatory recording.
|
|
| 3. |
- Alcaraz, Raul, et al.
(författare)
-
Organization tracking of long-term atrial fibrillation recordings: differences between paroxysmal and persistent episodes
- 2009
-
Ingår i: [Host publication title missing]. ; 36, s. 509-512
-
Konferensbidrag (refereegranskat)abstract
- In this work, a method for non-invasive assessment of AF organization has been applied to discriminating between paroxysmal and long-term persistent AF episodes. Following extraction of the atrial activity (AA) signal, the dominant atrial frequency (DAF) of the AA was computed based on a hidden Markov model. Finally, the main atrial wave (MAW) was obtained by bandpass filtering centered on the DAF, thus providing a time series suitable for AF organization estimation with sample entropy (SampEn). The performance of the method was evaluated on 24-h Holter recordings with long-term changes in AF organization. The results showed that episodes of paroxysmal AF (0.06930.0147) were consistently associated with lower SampEn than episodes with persistent AF (0.10560.0146). Moreover, 94.2% of 1-min segments with paroxysmal AF and 88.6% of 1-min segments with persistent AF could be correctly classified based on Samp- En information, thus making it possible to classify longterm recordings of patients without AF history.
|
|
| 4. |
|
|
| 5. |
- Tiraboschi, Juan M, et al.
(författare)
-
No changes in HIV suppression and inflammatory markers in CSF in patients randomly switched to DTG + 3TC (Spanish HIV/AIDS Research Network, PreEC/RIS 62).
- 2021
-
Ingår i: The Journal of infectious diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 223:11, s. 1928-1933
-
Tidskriftsartikel (refereegranskat)abstract
- A major concern of HIV dual therapy is a potential lower efficacy in viral reservoirs, especially in the central nervous system (CNS). We evaluated HIV RNA, neuronal injury and inflammatory biomarkers and dolutegravir (DTG) exposure in cerebrospinal fluid (CSF) in patients switching to DTG+lamivudine (3TC). All participants maintained viral suppression in plasma and CSF at week 48. We observed no increase in CSF markers of inflammation or neuronal injury. Median (IQR) total and unbound DTG in CSF were 7.3(5.9-8.4) ng/mL and 1.7(1.2-1.9) ng/mL, respectively. DTG+3TC may maintain viral control without changes in inflammatory/injury markers within the CNS reservoir.
|
|
| 6. |
- Vraka, Aikaterini, et al.
(författare)
-
Alternative Time-Domain P-wave Analysis for Precise Information on Substrate Alteration after Pulmonary Vein Isolation for Atrial Fibrillation
- 2021
-
Ingår i: 2021 9th E-Health and Bioengineering Conference, EHB 2021. - 9781665440004
-
Konferensbidrag (refereegranskat)abstract
- While P-wave duration (PWD) is primarily employed to observe the atrial substrate alterations after pulmonary vein isolation (PVI) on atrial fibrillation (AF) patients, the acquired information corresponds to the entire atria. Left (LA) and right atrium (RA), though, may be differently affected by PVI, implying the need for different after-PVI handling. In order to clarify this assumption, five-minute lead II recordings from 29 paroxysmal AF patients undergoing first-ever PVI were recruited before and after PVI. PWD was analyzed integrally and in parts, with the first part (PWD1) from the onset to the peak corresponding to RA and the second part (PWD2) to LA depolarization. Time from P-wave onset or offset to the R peak were also calculated (Pon - R and Poff - R, respectively). Normalization (N) to mitigate heart-rate effect was applied. Results before and after PVI were compared with Mann-Whitney U-test (MWU). Median values and variations due to PVI were calculated for all features and compared between PWD and the remaining features via Pearson correlation. After PVI, PWD (-9.84%, p = 0.0085, N: - 17.96%, p = 0.0442) and PWD2 (-22.03%, p = 0.0250, N: - 27.77%, p = 0.0268) were significantly decreased. PWD1 did not shorten significantly (up to -8.96%, p > 0.05 at either cases). PWD - PWD1 (ρ > 74.5%, p < 0.0001) showed higher correlation than PWD - PWD2 (ρ > 41.9%, p < 0.0001) in before and after PVI analysis but not for PVI-related variation (ρPWD-PWD1 = 54.0%, p = 0.0114 and ρPWD-PWD2 = 61.4%, p = 0.0031). While RA depolarization time is more in line with PWD analysis, the effect of PVI in PWD is more coherent with LA's findings. Additionally, PWD shortening is only observed in the LA. Therefore, LA is crucial for the assessment of the atrial substrate alteration after PVI and its analysis should be considered by future studies.
|
|
| 7. |
- Vraka, Aikaterini, et al.
(författare)
-
The P-Wave Time-Domain Significant Features to Evaluate Substrate Modification After Catheter Ablation of Paroxysmal Atrial Fibrillation
- 2022
-
Ingår i: 2022 Computing in Cardiology, CinC 2022. - 2325-8861 .- 2325-887X. - 9798350300970 ; 2022-September
-
Konferensbidrag (refereegranskat)abstract
- The outcome of catheter ablation (CA) of atrial fibrillation (AF) is vastly analyzed by the entire P-wave duration (PWD). However, the first and second P-wave parts, corresponding to right (RA) and left atrial (LA) wavefront propagation, may be unequally modified. Five-minute lead II recordings before and after the first-ever CA of 40 parox-ysmal AF patients were analyzed and P-wave features were calculated: PWDon-off of the entire P-wave and each P-wave part (RA:PWDon-peak, LA:PWDpeak-off) and the time from P-wave onset or offset to the R-peak (PWDon-R and PWDoff-R, respectively). Heart-rate (HR) adjustment (HRA) mitigated the HR fluctuations. Prelpost-CA comparison was performed with Mann-Whitney U-test and median values were calculated. Pearson's correlation was calculated between PWD and the remaining features. The effect of CA with (Δ: -17.96%) or without HRA (Δ: -9.84%) was significant at the entire PWDon-off and at the PWDpeak-off(HRA:Δ: -27.77%, no HRA: Δ: -22.03%). PWDon-off showed a stronger correlation with RA than LA(ρmax=0.805 vs ρmax=0.541). P-wave features corresponding to RA are more strongly related to the entire P-wave. Nevertheless, only the P-wave part associated with LA is significantly affected by CA. That being so, studies are encouraged to incorporate part-time P-wave analysis.
|
|
