| 1. |
- Corino, Valentina D.A., et al.
(författare)
-
A Mathematical Model of The Atrioventricular Node during Atrial Fibrillation
- 2010
-
Ingår i: [Host publication title missing]. - 0276-6574. ; 37, s. 117-120
-
Konferensbidrag (refereegranskat)abstract
- The atrioventricular (AV) node plays a crucial role during atrial fibrillation (AF). The aim of this study is to present an AV node model which can be fitted to short-term ECG recordings in order to infer certain AV node characteristics. The proposed model is characterized by: i) the arrival rate of atrial impulses; ii) two different refractory periods, corresponding to dual AV nodal paths; iii) the probability of an atrial impulse choosing either of these pathways; iv) a parameter modeling prolongation of the refractory period due to different physiological reasons. The model was tested on atrial fibrillatory ECGs recorded from 33 patients; the average normalized absolute error between the normalized RR histogram and the estimated model probability density function was 0.0023 ± 0.0016, (20-ms bin size, 0–2 s interval). These preliminary results are encouraging as AV nodal properties can be noninvasively assessed by a set of statistical parameters with a simple electrophysiological interpretation.
|
|
| 2. |
- Corino, Valentina D. A., et al.
(författare)
-
An Atrioventricular Node Model for Analysis of the Ventricular Response During Atrial Fibrillation
- 2011
-
Ingår i: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 58:12, s. 3386-3395
-
Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a model of the atrioventricular node function during atrial fibrillation (AF), and describes the related ECG-based estimation method. The proposed model is defined by parameters that characterize the arrival rate of atrial impulses, the probability of an impulse choosing either one of the two atrioventricular nodal pathways, the refractory periods of these pathways, and the prolongation of the refractory periods. These parameters are estimated from the RR intervals using maximum likelihood estimation, except for the shorter refractory period which is estimated from the RR interval Poincare plot, and the mean arrival rate of atrial impulses by the AF frequency. Simulations indicated that 200-300 RR intervals are generally needed for the estimates to be accurate. The model was evaluated on 30-min ECG segments from 36 AF patients. The results showed that 88% of the segments can be accurately modeled when the estimated probability density function (PDF) and an empirical PDF were at least 80% in agreement. The model parameters were estimated during head-up tilt test to assess differences caused by sympathetic stimulation. Both refractory periods decreased as a result of stimulation, and the likelihood of an impulse choosing the pathway with the shorter refractory period increased.
|
|
| 3. |
- Corino, Valentina D. A., et al.
(författare)
-
Association between Atrial Fibrillatory Rate and Heart Rate Variability in Patients with Atrial Fibrillation and Congestive Heart Failure
- 2013
-
Ingår i: Annals of Noninvasive Electrocardiology. - : Wiley. - 1082-720X. ; 18:1, s. 41-50
-
Tidskriftsartikel (refereegranskat)abstract
- Background Even if atrial fibrillatory rate (AFR) has been related to clinical outcome in patients with atrial fibrillation (AF), its relation with ventricular response has not been deeply studied. The aim of this study was to investigate the relation between AFR and RR series variability in patients with AF. Methods Twenty-minute electrocardiograms in orthogonal leads were processed to extract AFR, using spatiotemporal QRST cancellation and time frequency analysis, and RR series in 127 patients (age 69 +/- 11 years) with congestive heart failure (NYHA IIIII) enrolled in the MUSIC study (MUerte Subita en Insufficiencia Cardiaca). Heart rate variability and irregularity were assessed by time domain parameters and entropy-based indices, respectively and their correlation with AFR investigated. Results Variability measures seem not to be related to AFR, while irregularity measures do. A significant correlation between AFR and variability parameters of heart rate variability during AF was found only in patients not treated with antiarrhythmics drugs (correlation = 0.56 P < 0.05 for pNN50), while this correlation was lost in patients taking rate- or rhythm-control drugs. A significant positive correlation between AFR and indices of RR irregularity was found, showing that a higher AFR is related to a less organized RR series (correlation = 0.33 P < 0.05 for regularity index for all patients, correlation increased in subgroups of patients treated with the same drug). Conclusions These results suggest that a higher AFR is associated with a higher degree of irregularity of ventricular response that is observed regardless of the use of rate-controlling drugs. Ann Noninvasive Electrocardiol 2013;18(1):41-50
|
|
| 4. |
- Corino, Valentina D. A., et al.
(författare)
-
Atrioventricular nodal function during atrial fibrillation: Model building and robust estimation
- 2013
-
Ingår i: Biomedical Signal Processing and Control. - : Elsevier BV. - 1746-8094. ; 8:6, s. 1017-1025
-
Tidskriftsartikel (refereegranskat)abstract
- Statistical modeling of atrioventricular (AV) nodal function during atrial fibrillation (AF) is revisited for the purpose of defining model properties and improving parameter estimation. The characterization of AV nodal pathways is made more detailed and the number of pathways is now determined by the Bayesian information criterion, rather than just producing a probability as was previously done. Robust estimation of the shorter refractory period (i.e., of the slow pathway) is accomplished by a Hough-based technique which is applied to a Poincare plot of RR intervals. The performance is evaluated on simulated data as well as on ECG data acquired from AF patients during rest and head-up tilt test. The simulation results suggest that the refractory period of the slow pathway can be accurately estimated even in the presence of many artifacts. They also show that the number of pathways can be accurately determined. The results from ECG data show that the refined AV node model provides significantly better fit than did the original model, increasing from 85 +/- 5% to 88 +/- 4% during rest, and from 86 +/- 5% to 87 +/- 3% during tilt. When assessing the effect of sympathetic stimulation, the AF frequency increased significantly during tilt (6.25 +/- 0.58 Hz vs. 6.32 +/- 0.61 Hz, p <0.05, rest vs. tilt) and the prolongation of the refractory periods of both pathways decreased significantly (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 +/- 0.19s, p <0.05, rest vs. tilt). The results show that AV node characteristics can be assessed noninvasively for the purpose of quantifying changes induced by autonomic stimulation. (C) 2012 Elsevier Ltd. All rights reserved.
|
|
| 5. |
- Corino, Valentina D. A., et al.
(författare)
-
Beta-blockade and A1-adenosine receptor agonist effects on atrial fibrillatory rate and atrioventricular conduction in patients with atrial fibrillation
- 2014
-
Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092 .- 1099-5129. ; 16:4, s. 587-594
-
Tidskriftsartikel (refereegranskat)abstract
- Reduced irregularity of RR intervals in permanent atrial fibrillation (AF) has been associated with poor outcome. It is not fully understood, however, whether modification of atrioventricular (AV) conduction using rate-control drugs affects RR variability and irregularity measures. We aimed at assessing whether atrial fibrillatory rate (AFR) and variability and irregularity of the ventricular rate are modified by a selective A1-adenosine receptor agonist tecadenoson, beta-blocker esmolol, and their combination. Twenty-one patients (age 58 7 years, 13 men) with AF were randomly assigned to either 75, 150, or 300 g intravenous tecadenoson. Tecadenoson was administered alone (Dose Period 1) and in combination (Dose Period 2) with esmolol (100 g/kg/min for 10 min then 50 g/kg/min for 50 min). Heart rate (HR) and AFR were estimated for every 10 min long recording segment. Similarly, for every 10 min segment, the variability of RR intervals was assessed, as standard deviation, pNN20, pNN50, pNN80, and the root of the mean squared differences of successive RR intervals, and irregularity was assessed by non-linear measures such as regularity index (R) and approximate entropy. A marked decrease in HR was observed after both tecadenoson injections, whereas almost no changes could be seen in the AFR. The variability parameters were increased after the first tecadenoson bolus injection. In contrast, the irregularity parameters did not change after tecadenoson. When esmolol was infused, all the variability parameters further increased. Modification of AV node conduction can increase RR variability but does not affect regularity of RR intervals or AFR.
|
|
| 6. |
- Corino, Valentina D.A., et al.
(författare)
-
Non-invasive evaluation of the effect of metoprolol on the atrioventricular node during permanent atrial fibrillation
- 2014. - January
-
Ingår i: Computing in Cardiology 2014. - : Oxford University Press (OUP). - 2325-8861. - 9781479943463 - 9781479943470 ; 41, s. 889-892
-
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.
|
|
| 7. |
- Corino, Valentina D A, et al.
(författare)
-
Statistical modeling of atrioventricular nodal function during atrial fibrillation : An update
- 2013
-
Ingår i: BIOSIGNALS 2013 - Proceedings of the International Conference on Bio-Inspired Systems and Signal Processing. - 9789898565365 ; , s. 25-29
-
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.
|
|
| 8. |
- Corino, Valentina D. A., et al.
(författare)
-
Statistical Modeling of Atrioventricular Nodal Function During Atrial Fibrillation Focusing on the Refractory Period Estimation
- 2014
-
Ingår i: Biomedical Engineering Systems and Technologies (Biostec 2013). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1865-0929. ; 452, s. 258-268
-
Konferensbidrag (refereegranskat)abstract
- We have recently proposed a statistical AV node model defined by a set of parameters characterizing the arrival rate of atrial impulses, the probability of an impulse passing through the fast or the slow pathway, the refractory periods of the pathways, and the prolongation of refractory periods. All parameters are estimated from the RR interval 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. In this chapter, we compare four different methods, based either on the Poincare plot or ML estimation, for determining the refractory period of the slow pathway. Simulation results show better performance of the ML estimator, especially in the presence of artifacts due to premature ventricular beats or misdetected beats. The performance was also evaluated on ECG data acquired from 26 AF patients during rest and head-up tilt test. During tilt, the AF frequency increased (6.08 +/- 1.03 Hz vs. 6.20 +/- 0.99 Hz, p < 0.05, rest vs. tilt) and the refractory periods of both pathways decreased (slow pathway: 0.43 +/- 0.12 s vs. 0.38 +/- 0.12 s, p = 0.001, rest vs. tilt; fast pathway: 0.55 +/- 0.14 s vs. 0.47 +/- 0.11 s, p < 0.05, rest vs. tilt). These results show that AV node characteristics can be assessed non-invasively to quantify changes induced by autonomic stimulation.
|
|
| 9. |
- Corino, Valentina D.A., et al.
(författare)
-
Statistical modeling of the atrioventricular node during atrial fibrillation : Data length and estimator performance
- 2013
-
Ingår i: 2013 35th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2013. - 9781457702167 ; , s. 2567-2570
-
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.
|
|
| 10. |
- Sandberg, Frida, et al.
(författare)
-
Drug effect evaluation during permanent atrial fibrillation using an AV-node model
- 2013
-
Ingår i: Computing in Cardiology 2013, CinC 2013. - 9781479908844 ; 40, s. 1243-1246
-
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.
|
|
