| 1. |
- Albano, Amanda, et al.
(author)
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Echocardio-variability - Low and high frequency beat-to-beat variability in echocardiographic signals
- 2013
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In: Computing in Cardiology 2013. - 9781479908844 ; , s. 767-770
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Conference paper (peer-reviewed)abstract
- Measurement signals originating from the cardiovascular system are known to comprise oscillating components and beat-to-beat variability, e.g., heart-rate variability and blood pressure variability. In clinical echocardiographic procedures, typically only a few cardiac cycles are acquired. This pilot study analyses the beat-to-beat variability of echocardiographic variables (echocardio-variability) in minute long acquisitions.
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| 2. |
- Granåsen, Gabriel, et al.
(author)
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Multivariate Classification of Cardiac Autonomic Function and Echocardiographic Abnormalities
- 2013
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In: 2013 COMPUTING IN CARDIOLOGY CONFERENCE (CINC). - 9781479908844 ; , s. 1151-1154
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Conference paper (peer-reviewed)abstract
- Abnormalities in the function, physiology and the regulation of the heart can be diagnosed using echocardiography (ECHO) and analysis of heart rate variability (HRV). Patients with transthyretin amyloidosis often present increased wall thickness in the myocardium and/ or autonomic dysfunction. We used a novel approach to analyse the relationship between these findings, using a combination of dimension reduction techniques and model based clustering.
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| 3. |
- Lazaro, Jesus, et al.
(author)
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Electrocardiogram derived respiration from QRS slopes : Evaluation with stress testing recordings
- 2013
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In: 2013 Computing in Cardiology. - 9781479908844 ; 40, s. 655-658
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Conference paper (peer-reviewed)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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| 4. |
- Petrenas, Andrius, et al.
(author)
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A noise-adaptive method for detection of brief episodes of paroxysmal atrial fibrillation
- 2013
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In: 2013 Computing in Cardiology. - 9781479908844 ; 40, s. 739-742
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Conference paper (peer-reviewed)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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| 5. |
- Riveros, F., et al.
(author)
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Influence of intraluminal thrombus topology on AAA passive mechanics
- 2013
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In: 2013 40th Computing in Cardiology Conference, CinC 2013. - : IEEE Computer Society. - 9781479908844 ; , s. 899-902
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Conference paper (peer-reviewed)abstract
- An intraluminal thrombus (ILT) is found in most AAAs of clinically relevant size. Even though some studies seem to indicate a protective role of the ILT against AAA rupture, there is still great controversy on this regard. In addition, patient-specific AAA models are generated from gated medical images in which the artery is under pressure. Identification of the AAA zero pressure geometry would allow for a more realistic estimate of the aneurysmal wall mechanics and a better understanding of the role of the ILT. This study looks into the influence of the ILT on patient specific AAA accounting for the zero pressure geometry. Ten patient specific AAA of similar maximum diameter (4.8-5.2cm) and ILT volume were considered. For the stress analysis, the arterial wall is modeled as an anisotropic hyperelastic solid. Our results suggest that the geometrical configuration of the ILT relative to the arterial wall may be an influential factor not only on the ensuing peak wall stress, but also on its location within the lesion. The effects of the ILT topology are enhanced when the zero pressure configuration of the lesion is accounted for, where as the location of the peak wall stress in the lesion corresponds to the region of minimal ILT thickness. These suggest that the topology of the ILT, which greatly influence the zero-pressure geometry of the AAA, affects the stress field at the systolic pressure on AAA.
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| 6. |
- Sandberg, Frida, et al.
(author)
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Drug effect evaluation during permanent atrial fibrillation using an AV-node model
- 2013
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In: Computing in Cardiology 2013, CinC 2013. - 9781479908844 ; 40, s. 1243-1246
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Conference paper (peer-reviewed)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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| 7. |
- Sandberg, Frida, et al.
(author)
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Prediction of intradialytic hypotension using PPG and ECG
- 2013
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In: 2013 Computing in Cardiology. - 9781479908844 ; 40, s. 1227-1230
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Conference paper (peer-reviewed)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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| 8. |
- Wiklund, Urban, et al.
(author)
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Cardiorespiratory Coherence Analysis of Abnormal Heart Rate Responses during Deep Breathing
- 2013
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In: 2013 COMPUTING IN CARDIOLOGY CONFERENCE (CINC). - 9781479908844 ; , s. 109-112
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Conference paper (peer-reviewed)abstract
- Although the heart rate variability (HRV) normally is highly synchronised with respiration during deep breathing, in patients with transthyretin amyloidosis we occasionally observe abnormal heart rate responses due to subtle arrhythmias, This study evaluates the use of cardiorespiratory coherence analysis for automatic detection of these abnormal patterns.
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