| 1. |
- Corino, Valentina D.A., et al.
(författare)
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Non-invasive evaluation of the effect of metoprolol on the atrioventricular node during permanent atrial fibrillation
- 2014. - January
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Ingår i: Computing in Cardiology 2014. - : Oxford University Press (OUP). - 2325-8861. - 9781479943463 - 9781479943470 ; 41, s. 889-892
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Konferensbidrag (refereegranskat)abstract
- The aim of this study was to evaluate changes in AV nodal properties during administration of metoprolol, using a novel ECG-based method for parameter estimation. The AV nodal parameters account for the probability of an impulse not passing through the fast pathway, the absolute refractory periods of the slow and fast pathways (aRPs and aRPf), representing the functional refractory period, and related prolongation in the respective refractory periods. Twenty patients (age 71±8 years, 14 men) with permanent AF from the RATe control in Atrial Fibrillation (RATAF) database were included in this study. Recordings during baseline and metoprolol administration were analyzed. Furthermore, simulated RR series were generated mimicking metoprolol administration. During metoprolol administration, aRP was significantly prolonged in both pathways (aRPs: 342±39 vs. 408±81 ms, p<0.001; aRPf: 432±74 vs. 527±83 ms, p<0.001). Similar results were found for the simulated RR series: both aRPs and aRPf were significantly prolonged with metoprolol. The AV nodal parameters reflect expected changes after metoprolol administration, i.e., a prolongation in functional refractory period. The simulations suggest that aRP may serve as an estimate of the functional refractory period.
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| 2. |
- Corino, Valentina D A, et al.
(författare)
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Statistical modeling of atrioventricular nodal function during atrial fibrillation : An update
- 2013
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Ingår i: BIOSIGNALS 2013 - Proceedings of the International Conference on Bio-Inspired Systems and Signal Processing. - 9789898565365 ; , s. 25-29
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a number of advancements of our recently proposed model of atrioventricular (AV) node function during atrial fibrillation (AF). The model is defined by parameters characterizing the arrival rate of atrial impulses, the probability of an impulse choosing either one of the two AV nodal pathways, the refractory periods of these pathways, and their prolongation. In the updated model, the characterization of AV nodal pathways is made more detailed and the number of pathways is determined by the Bayesian information criterion. The performance is evaluated on ECG data acquired from twenty-five AF patients during rest and head-up tilt test. The results show that the refined AV node model provides significantly better fit than did the original model. During tilt, the AF frequency increased (6.25 ±0.58 Hz vs. 6.32 ±0.61 Hz, p < 0.05, rest vs. tilt) and the prolongation of the refractory periods decreased for both pathways (slow pathway: 0.23 ±0.20 s vs. 0.11 ±0.10 s, p < 0.001, rest vs. tilt; fast pathway: 0.24±0.31 s vs. 0.16±0.19 s, p < 0.05, rest vs. tilt). These results show that AV node characteristics can be assessed noninvasively for the purpose of quantifying changes induced by autonomic stimulation.
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| 3. |
- Corino, Valentina D.A., et al.
(författare)
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Statistical modeling of the atrioventricular node during atrial fibrillation : Data length and estimator performance
- 2013
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Ingår i: 2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2013. - 9781457702167 ; , s. 2567-2570
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Konferensbidrag (refereegranskat)abstract
- The atrioventricular (AV) node plays a central role during atrial fibrillation (AF). We have recently proposed a statistical AV node model defined by parameters characterizing the arrival rate of atrial impulses, the probability of an impulse choosing either one of the dual AV nodal pathways, the refractory periods of the pathways, and the prolongation of refractory periods. All model parameters are estimated from the RR series using maximum likelihood (ML) estimation, except for the mean arrival rate of atrial impulses which is estimated by the AF frequency derived from the f-waves. The aim of this study is to present a unified approach to ML estimation which also involves the shorter refractory period, thus avoiding our previous Poincaré plot analysis which becomes biased. In addition, the number of RR intervals required for accurate parameter estimation is presented. The results show that the shorter refractory period can be accurately estimated, and that the resulting estimates converge to the true values when about 500 RR intervals are available.
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| 4. |
- Lazaro, Jesus, et al.
(författare)
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Electrocardiogram derived respiration from QRS slopes : Evaluation with stress testing recordings
- 2013
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Ingår i: 2013 Computing in Cardiology. - 9781479908844 ; 40, s. 655-658
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Konferensbidrag (refereegranskat)abstract
- A method for respiratory rate estimation from electrocardiogram (ECG), based on variations in QRS complexes slopes, is evaluated over stress testing recordings. Besides the 12 standard, and the 3 vectorcardiogram (VCG), 2 additional leads derived from the VCG are analyzed. A total of 34 slope series were studied, 2 for each lead: slopes between the peaks of the Q and R waves, and between the peaks of the R and S waves. Respiratory rate is estimated by using a time-frequency based algorithm which can combine information from several derived respiration signals. Evaluation was performed over a database containing ECG and respiratory signals simultaneously recorded from 30 subjects spontaneously breathing during a stress test. Respiratory rate estimation is performed with information of 4 different combinations of QRS slope series. The best results in respiratory rate estimation error terms are -1.07 ± 8.86% (-11.47 ± 37.97 mHz). These results suggest that proposed methods based on QRS slopes are highly suitable for respiratory rate estimation from ECG signal, specially at very non-stationary and noise scenarios as stress test.
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| 5. |
- Petrenas, Andrius, et al.
(författare)
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A noise-adaptive method for detection of brief episodes of paroxysmal atrial fibrillation
- 2013
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Ingår i: 2013 Computing in Cardiology. - 9781479908844 ; 40, s. 739-742
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Konferensbidrag (refereegranskat)abstract
- The aim of this work is to develop a method for detection of brief episode paroxysmal atrial fibrillation (PAF). The proposed method utilizes four different features: RR interval irregularity, absence of P waves, presence of f-waves and noise level. The obtained features are applied to the Mamdani-type fuzzy inference method for decisionmaking. The performance was evaluated on one hundred 90 s long surrogate ECG signals with brief PAF episodes (5-30 beats). The robustness to noise in ECGs where noise level in each set is incremented in steps of 0.01 mV from 0 to 0.2 mV was examined as well. When compared to the coefficient of sample entropy, our method showed considerably better performance for low and moderate noise levels (< 0.06 mV) with an area under the receiver operating characteristic curve of 0.9 and 0.94, respectively. Similar performance is expected for higher noise levels as atrial activity is less used in the detection process. Finally, the results suggest that our method is more robust to false alarms due to ectopic beats or other irregular rhythms than the method under comparison.
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| 6. |
- Petrenas, Andrius, et al.
(författare)
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Reservoir computing for extraction of low amplitude atrial activity in atrial fibrillation
- 2012
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Ingår i: 2012 Computing in Cardiology. - 9781467320740 ; 39, s. 13-16
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Konferensbidrag (refereegranskat)abstract
- A novel method for QRST cancellation during atrial fibrillation (AF) is introduced for use in recordings with two or more leads. The method is based on an echo state neural network (ESN) which estimates the time-varying, nonlinear transfer function between two leads, one lead with atrial activity and another lead without, for the purpose of canceling ventricular activity. The performance is evaluated on ECG signals, with simulated f-waves of low amplitude added, by determining the root mean square error P between the true f-wave signal and the estimated signal, as well as by evaluating the dominant AF frequency. When compared to average beat subtraction (ABS), being the most widely used method for QRST cancellation, the performance is found to be significantly better with equal to mean and standard deviation of PESN 24.8±7.3 and PABS 34.2±17.9 μV (p < 0.001). The novel method is particularly well-suited for implementation in mobile health systems where monitoring of AF during extended time periods is of interest.
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| 7. |
- Sandberg, Frida, et al.
(författare)
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Drug effect evaluation during permanent atrial fibrillation using an AV-node model
- 2013
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Ingår i: Computing in Cardiology 2013, CinC 2013. - 9781479908844 ; 40, s. 1243-1246
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Konferensbidrag (refereegranskat)abstract
- The purpose of the present study is to evaluate the effect of rate control drugs on the AV node characteristics during atrial fibrillation (AF) using a model-based approach. A statistical model of the AV nodal function is employed, defined by parameters which characterize the arrival rate of atrial impulses, the refractoriness of the fast and the slow AV-nodal pathway and the probability of atrial impulse to pass through either of the two pathways. The RATAF (RATe control in Atrial Fibrillation) study database consists of recordings from 60 patients with permanent AF at baseline and on treatment with metoprolol, verapamil, diltiazem and carvedilol, respectively. The resulting model parameter estimates indicate that the refractory period of the slow pathway as well as that of the fast pathway increased significantly during treatment with all four drugs. The results suggest that the proposed AV-node model can be used for non-invasive evaluation of the effect of rate control drugs.
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| 8. |
- Sandberg, Frida, et al.
(författare)
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Prediction of intradialytic hypotension using PPG and ECG
- 2013
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Ingår i: 2013 Computing in Cardiology. - 9781479908844 ; 40, s. 1227-1230
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Konferensbidrag (refereegranskat)abstract
- Intradialytic hypotension (IDH) is the most common complication during hemodialysis; early prediction and prevention of IDH would dramatically improve the living conditions for patients with end stage renal disease. A recently published study suggests that a decrease in the envelope of the photoplethysmograpy (PPG) signal can be used for predicting acute symptomatic IDH. In the present study, the PPG based method is extended by introducing a patient dependent detection threshold, which involves information on heart rate variability (HRV) and heart rate turbulence (HRT) from the current dialysis session. This is motivated since several studies have found significant differences in HRV and HRT between hypotension-prone and hypotension-resistant patients. Recordings from 15 patients during 38 hemodialysis sessions were used to evaluate the method. Symptomatic IDH was correctly predicted in 9 out of 14 cases, while 5 out of 24 cases were falsely predicted. The performance was better for acute symptomatic IDH, 5 out of 5 cases were correctly predicted. The present method represents a novel approach to combining information derived from ECG and PPG signals.
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