| 1. |
- Martinez, J P, et al.
(författare)
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Accuracy of QT Measurement in the EASI-derived 12-lead ECG
- 2006
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Ingår i: Conference proceedings (IEEE Engineering in Medicine and Biology Society. Conf.). - 1557-170X. ; 1, s. 3986-3989
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study is to assess QT interval measurements from the EASI 12-lead ECG as compared to the standard 12-lead ECG. The QT interval was automatically measured in simultaneously recorded standard and EASI 12- lead ECGs, using a validated wavelet-based delineator. The agreement between the two sets of measurements was quantified both on a lead-by-lead basis and a multilead basis. The results show an acceptable agreement between QT measurements in the two lead systems, with correlation coefficients (CC) 0.91-0.98 depending on the lead. Standard deviations range from 9.2 ms to 26.4 ms depending on the selected lead. In a few patients large inter-system differences were found, mainly due to different T wave morphologies. Using a multilead delineation, QT intervals were considerably more stable than single-lead measurements and resulted in a much better agreement between the two lead systems (CC: 0.98, QT difference: 1.1 ms ± 9.8 ms). Thus, EASI-derived 12- lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted.
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| 2. |
- Smith, Danny, et al.
(författare)
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Heart Rate Turbulence Detection Using Mean Shape Information
- 2009
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Ingår i: CINC: 2009 36th Annual Computers in Cardiology Conference. - 0276-6574. ; , s. 153-156
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Konferensbidrag (refereegranskat)abstract
- In this study, we propose a generalized likelihood ratio test statistic for detection of heart rate turbulence (HRT) based on a linear signal model. The new test statistic, which expands our previous original detector; takes a priori information regarding HRT shape into account. The detector structure is based on the extended integral pulse frequency modulation model which accounts for the presence of ectopic beats and HRT The spectral relationship between heart rate variability (HRV) and HRT is investigated for the purpose of modeling HRV "noise" present during the turbulence period. The performance was studied for both simulated data and real data obtained from the Long-Term ST database. The results show that the new detector is superior to the original one as well as to the commonly used parameter turbulence slope (TS) on both types of data.
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| 3. |
- Albers, P, et al.
(författare)
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Guidelines on testicular cancer
- 2005
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Ingår i: European urology. - : Elsevier BV. - 0302-2838. ; 48:6, s. 885-894
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Tidskriftsartikel (refereegranskat)
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| 4. |
- Bailon, R, et al.
(författare)
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A robust method for ECG-Based estimation of the respiratory frequency during stress testing
- 2006
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 53:7, s. 1273-1285
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Tidskriftsartikel (refereegranskat)abstract
- A robust method is presented for electrocardiogram (ECG)-based estimation of the respiratory frequency during stress testing. Such ECGs contain highly nonstationary noise and exhibit changes in QRS morphology which, when combined with the dynamic nature of the respiratory frequency, make most existing methods break down. The present method exploits the oscillatory pattern of the rotation angles of the heart's electrical axis as induced by respiration. The series of rotation angles, obtained from least-squares loop alignment, is subject to power spectral analysis and estimation of the respiratory frequency. Robust techniques are introduced to handle the nonstationary properties of exercise ECGs. The method is evaluated by means of both simulated signals, and ECG/airflow signals recorded from 14 volunteers and 20 patients during stress testing. The resulting respiratory frequency estimation error is, for simulated signals, equal to 0.5% +/- 0.2%, mean SD (0.002 +/- 0.001 Hz), whereas the error between respiratory frequencies of the ECG-derived method and the airflow signals is 5.9 % +/- 4 % (0.022 +/- 0.016 Hz). The results suggest that the method is highly suitable for analysis of noisy ECG signals recorded during stress testing.
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| 5. |
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| 6. |
- Gravas, S, et al.
(författare)
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Seeking evidence that cell kill guided thermotherapy gives results not inferior to those of transurethral prostate resection: Results of a pooled analysis of 3 studies of feedback transurethral microwave thermotherapy
- 2005
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Ingår i: Journal of Urology. - : Ovid Technologies (Wolters Kluwer Health). - 1527-3792 .- 0022-5347. ; 174:3, s. 1002-1006
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: We compared ProstaLund Feedback Treatment(R) (PLFT(R)) to transurethral prostate resection (TURP) in terms of efficacy and safety in a pooled analysis of 3 clinical studies with 1-year followup. Materials and Methods: Overall raw data on 183 patients with PLFT(R) and 65 with TURP were pooled. All studies had identical inclusion criteria, and the efficacy and safety of the method were evaluated using the International Prostate Symptom Score, maximum urine flow (Qmax), responder rate, bother score, prostate volume reduction and adverse events. Results: The response rate was 85.3% and 85.9% in the PLFT(R) and TURP groups, respectively. One-sided 95% CI analysis showed the noninferiority of PLFT(R) vs TURP for this variable. Mean International Prostate Symptom Score was significantly decreased in the PLFT(R) and TURP groups after 12 months (from 20.9 to 6.4 and 20.7 to 7.1, respectively). The 1-sided upper 95% CI of PLFT(R) was within the noninferiority definition compared with that of TURP. The bother score decrease in the PLFT(R) and TURP groups was not significant different (70.9% and 64.0%, respectively). An increase in Qmax from 7.7 to 16.1 ml per second 12 months after PLFT(R) was noted, while the improvement in Qmax in the TURP group was higher (from 7.5 to 18.6 ml per second). The 1-sided lower 95% CI was close (0.76) but it did not attain the predetermined level of noninferiority (0.80). Mean transurethral ultrasound determined volume 12 months after PLFT(R) and TURP was reduced by 32.8% and 58.1%, respectively. A significant correlation between the transurethral ultrasound determined prostate volume reduction and estimated cell kill was found (r = 0.456, p <0.000001). Serious adverse events with causality occurred in 15.4% of patients with TURP compared with 6.0% in those with PLFT(R) (p = 0.035). Conclusions: Combined experience from our pooled analysis indicates that PLFT(R) challenges TURP in terms of efficacy and safety after 1 year of followup.
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| 7. |
- Martínez Cortés, Juan Pablo, et al.
(författare)
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Risk stratification in congestive heart failure patients using a model-based approach to heart rate turbulence characterization
- 2009
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Ingår i: Computers in Cardiology 2009, CinC 2009. - 9781424472819 ; 36, s. 337-340
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Konferensbidrag (refereegranskat)abstract
- Heart rate turbulence (HRT) is commonly assessed by two parameters: turbulence onset (TO) and turbulence slope (TS), both obtained by averaging RR tachograms following a ventricular premature beat (VPB). It has been recently shown that a model-based detection-theoretical approach results in HRT indices outperforming TO/TS in identifying the presence or absence of HRT. The aim of this work is to evaluate the risk stratification ability of this approach, as compared with the classical parameters TO and TS, in a population of 96 ischemic patients with mild to moderate congestive heart failure. We found signifi-cant differences (Mann-Withney U test) between survivors and cardiac death groups for TS and the new parameter TΣ(x). Survival analysis showed that TΣ(x) is the HRT index with highest association to risk of cardiac death (hazard ratio=2.8, p =0.008). Results show improved risk stratification of the new description of HRT with respect to classical parameters.
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| 8. |
- Solem, Kristian, et al.
(författare)
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An efficient method for handling ectopic beats using the heart timing signal
- 2006
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Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 53:1, s. 13-20
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Tidskriftsartikel (refereegranskat)abstract
- The problem of analyzing heart rate variability in the presence of ectopic beats is revisited. Based on the integral pulse frequency modulation model and the closely related heart timing signal, a new technique is introduced which corrects for the occasional presence of ectopic beats. The correction technique, which involves the occurrence times of a certain number of beats preceding the ectopic beat, is computationally very efficient. From actual heart rate data, the results show that the new technique is associated with a much lower computational complexity (flops reduced by a factor of about 3000) than the original heart timing technique, while producing similar performance. It is also shown that the power spectrum and related clinical indices obtained by the new technique are more accurately estimated than by other methods.
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| 9. |
- Sörnmo, Leif, et al.
(författare)
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El procesado de señales en medicina
- 2007
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Ingår i: Procesado de señales biomédicas. - 9788484275411 ; , s. 7-26
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Sörnmo, Leif, et al.
(författare)
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Electrocardiogram (ECG) Signal Processing
- 2006
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Ingår i: Wiley encyclopedia of biomedical engineering. - Hoboken, NJ, USA : John Wiley & Sons, Inc.. - 9780471249672 ; 2, s. 1298-1313
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Signal processing of electrocardiographic signals has a long and rich history and has greatly helped to enhance the diagnostic capability, especially when signals are recorded in noisy environments. This article gives an introductory presentation of the basic set of algorithms used for conditioning the ECG with respect to different types of noise and artifacts, detecting heartbeats, extracting basic ECG measurements, and performing data compression. Signal processing in clinical applications is exemplified by the high-resolution ECG and T wave alternans.
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