| 1. |
- Barquero-Perez, Oscar, et al.
(författare)
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On the influence of heart rate and coupling interval prematurity on heart rate turbulence
- 2017
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 64:2, s. 302-309
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Heart rate turbulence (HRT) has been successfully explored for cardiac risk stratification. While HRT is known to be influenced by the heart rate (HR) and the coupling interval (CI), nonconcordant results have been reported on how the CI influences HRT. The purpose of this study is to investigate HRT changes in terms of CI and HR by means of an especially designed protocol. Methods: A dataset was acquired from 11 patients with structurally normal hearts for which CI was altered by different pacing trains and HR by isoproterenol during electrophysiological study (EPS). The protocol was designed so that, first, the effect of HR changes on HRT and, second, the combined effect of HR and CI could be explored. As a complement to the EPS dataset, a database of 24-h Holters from 61 acute myocardial infarction (AMI) patients was studied for the purpose of assessing risk. Data analysis was performed by using different nonlinear ridge regression models, and the relevance of model variables was assessed using resampling methods. The EPS subjects, with and without isoproterenol, were analyzed separately. Results: The proposed nonlinear regression models were found to account for the influence of HR and CI on HRT, both in patients undergoing EPS without isoproterenol and in low-risk AMI patients, whereas this influence was absent in high-risk AMI patients. Moreover, model coefficients related to CI were not statistically significant, p > 0.05, on EPS subjects with isoproterenol. Conclusion: The observed relationship between CI and HRT, being in agreement with the baroreflex hypothesis, was statistically significant (p < 0.05), when decoupling the effect of HR and normalizing the CI by the HR. Significance: The results of this study can help to provide new risk indicators that take into account physiological influence on HRT, as well as to model how this influence changes in different cardiac conditions.
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| 2. |
- Goya-Esteban, Rebeca, et al.
(författare)
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Long-term characterization of persistent atrial fibrillation: wave morphology, frequency, and irregularity analysis
- 2014
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Ingår i: Medical & Biological Engineering & Computing. - : Springer Science and Business Media LLC. - 0140-0118 .- 1741-0444. ; 52:12, s. 1053-1060
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Tidskriftsartikel (refereegranskat)abstract
- Short-term properties of atrial fibrillation (AF) frequency, f-wave morphology, and irregularity parameters have been thoroughly studied, but not long-term properties. In the present work, f-wave morphology is characterized by principal component analysis, introducing a novel temporal parameter defined by the cumulative normalized variance of the three largest principal components . Based on 7-day recordings from nine patients with stable chronic heart failure and persistent AF, long-term properties were studied in terms of , AF frequency, and sample entropy . The main result of the present study is that detection of circadian rhythms depends on the parameter considered: rhythms were found in six and five (AF frequency) patients, but not always in the same patient. Another important result is that circadian rhythms detected in 7-day recordings could not always be detected in 24-h periods, thus shedding new light on the results in previous studies which all were based on 24-h recordings. Infradian rhythms were found in four and one (AF frequency) patients.
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| 3. |
- Goya-Esteban, Rebeca, et al.
(författare)
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Seven-day analysis of atrial fibrillation and circadian rhythms
- 2013
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Ingår i: BIOSIGNALS 2013 - Proceedings of the International Conference on Bio-Inspired Systems and Signal Processing. - 9789898565365 ; , s. 20-24
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Konferensbidrag (refereegranskat)abstract
- In the present work, f-wave morphology is characterized by principal component analysis and a novel temporal parameter defined by the cumulative normalized variance of the 3 largest principal components (r3). The 7-day behavior of persistent atrial fibrillation (AF) was studied in 9 patients using r3, AF frequency, and sample entropy (SampEn). Detection of circadian rhythms depended on the parameter considered: rhythms were found in 6 (r3, SampEn) and 5 (AF frequency) patients, but interestingly not always in the same patients. Two patients had significant circadian rhythm in all parameters. When a circadian rhythm was significantly present in 7 days, it was usually only significantly present in some of the 24-h segments. It is concluded that detailed AF characterization can be achieved with complementary parameters.
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