Scheduled System Maintenance:
On May 6th, single article purchases and IEEE account management will be unavailable from 8:00 AM - 5:00 PM ET (12:00 - 21:00 UTC). We apologize for the inconvenience.
By Topic

Date Sept. 30 2007-Oct. 3 2007

Filter Results

Displaying Results 1 - 25 of 217
  • Development of a method for left ventricular shape evaluation based on surfaces obtained by real-time 3D echocardiographic images

    Publication Year: 2007 , Page(s): 1 - 4
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1793 KB) |  | HTML iconHTML  

    Left ventricular (LV) shape is strictly related to LV function. Previously proposed shape indexes suffer from their intrinsic 2D nature. Our aim was to develop a method to quantify directly 3D LV shape from LV surfaces semi-automatically detected from real-time 3D echocardiographic (RT3DE) images. First, a monodimensional shape descriptor has been obtained by sampling through an helical pattern the extracted endocardial surfaces. Then, four shape indexes have been defined by comparing the LV with reference shapes. The developed method was applied to RT3DE datasets obtained from 12 normal subjects, 8 patients with dilated cardiomiopathy and 7 ischemic patients. Some of the proposed shape indexes were able to follow chamber deformation throughout the cardiac cycle and to discriminate between normal and pathologic conditions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A multilead approach to T-wave alternans detection combining principal component analysis and the Laplacian likelihood ratio method

    Publication Year: 2007 , Page(s): 5 - 8
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1489 KB) |  | HTML iconHTML  

    Several methods have been proposed to automatically detect and estimate T-wave alternans (TWA) in the ECG, all of them operating on a single-lead basis. In this study a multilead detection scheme is proposed. It combines principal component analysis with the Laplacian likelihood ratio method to improve the detection results. A simulation is carried out to evaluate the effect of different types of simulated and physiological noise, and to assess the performance of this detection scheme. According to simulation results, the proposed multilead approach can detect alternans with a SNR 30 dB lower than the single-lead approach, showing a remarkable improvement of the sensitivity to low-level alternans. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Location of myocardium at risk in comparison between single photon emission computed tomography, magnetic resonance imaging and electrocardiography

    Publication Year: 2007 , Page(s): 9 - 12
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2339 KB) |  | HTML iconHTML  

    The aim of the present study was to test the hypothesis that perfusion SPECT, estimation of regional wall thickening using MRI and the distribution of ST changes on the admission ECG display similar localization of the MaR in patients with reperfused first-time MI. Eleven patients with first-time MI with ST-elevation underwent percutaneous coronary intervention (PCI), SPECT imaging within 3 hours of the PCI and Cardiac MRI the day after admission. All images were presented in polar plots and compared with polar plots generated from the initial ECG's, based upon ST-changes. Comparison of the displays reveals similarity of location of myocardium at risk by all three methods in 73% of the patients, between SPECT and ECG in 91% of the patients, and between SPECT and wall thickening by MRI in 73% of the patient. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Co-registration of doppler tissue synchronization imaging and computer tomography with an application to pacing and cardiac resynchronization therapy

    Publication Year: 2007 , Page(s): 13 - 16
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1547 KB) |  | HTML iconHTML  

    Dyssynchronous myocardial contraction can be treated with surgical implant of a pacing device. Integrated information of coronary anatomy and mechanical delay may be extremely beneficial to success of the implant but it is not available in current cardiac imaging modalities. The objective of this study is to investigate the feasibility of a point-merge co-registration approach to overcome the limitation. This study shows that our method is a reliable and fast tool useful not only to attain optimal left ventricular implantation site but also to better select patients that undergo cardiac resynchronization therapy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Variations of HRV analysis in different approaches

    Publication Year: 2007 , Page(s): 17 - 20
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1783 KB) |  | HTML iconHTML  

    The analysis of normal-to-normal (NN) intervals acquired from a continuous electrocardiogram (ECG) record is a standard method to evaluate the variations in heart rate. For the advantage of responding to the pumping action of the heart, photoplethysmography (PPG) has also been used extensively in the analysis of heart rate variability (HRV). However, there is little literature available on the variation between the HRV analysis derived from ECG and PPG. In the research described here, experiments of recording short-term (les 5 minutes) ECG and PPG signals simultaneously from healthy subjects (male, N=10) under control were carried out to investigate the possibility of such variation. Automatic computer analysis is provided for the analysis of correlation coefficient and the LF/HF ratio by autoregressive (AR) spectral analysis for evenly resampled sequences. The identical results are highly expected. However, the correlation coefficient between RRI (R-R interval from ECG) and PPI (peak-to-peak interval from PPG) is 0.86plusmn0.15, which should be unity for perfectly matched patterns. In additions, the relative LF/HF ratios are 2.49plusmn1.13 (for ECG) and 2.73plusmn0.82 (for PPG) respectively. Though there is no statistical difference, the worst likelihood ratio (LR) reaches the deviation of 19.04%. From the experimental results, it can be appreciated that there is indeed variation for HRV analysis in two different approaches even for healthy subjects under well-controlled conditions. For abnormal subjects in clinical applications, such variation may be expected to become more apparent. Though the variation is minor, it is suggested to obey the standard measure of HRV proposed by Task Force for consistent conclusions. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Long-range dependence in heart rate variability data: ARFIMA modelling vs detrended fluctuation analysis

    Publication Year: 2007 , Page(s): 21 - 24
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1566 KB) |  | HTML iconHTML  

    Heart rate variability (HRV) data display non-stationary characteristics and exhibit long-range correlation (memory). Detrended fluctuation analysis (DFA) has become a widely-used technique for long memory estimation in non-stationary HRV data. Recently, we have proposed an alternative approach based on fractional integrated autoregressive moving average (ARFIMA) models. ARFIMA models, combined with selective adaptive segmentation may be used to capture and remove long-range correlation, leading to an improved description and interpretation of the components in 24 hour HRV recordings. In this work estimation of long memory by DFA and selective adaptive ARFIMA modelling is carried out in 24 hour HRV recordings of 17 healthy subjects of two age groups. The two methods give similar information on long-range global characteristics. However, ARFIMA modelling is advantageous, allowing the description of long-range correlation in reduced length segments. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of physiological meaning of detrended Fluctuation Analysis in Heart Rate Variability using a lumped parameter model

    Publication Year: 2007 , Page(s): 25 - 28
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1974 KB) |  | HTML iconHTML  

    Chaos and fractal based measurements, such as detrended fluctuation analysis (DFA), have been widely used for quantifying the heart rate variability (HRV) for cardiac risk stratification purposes. However, the physiological meaning of these measurements is not clear. Given that existing lumped parameter models contain a detailed physiological description of several of the circulatory system regulation processes, we hypothesize that controlled changes in these processes will highlight the physiological basis in DFA indices. We used a detailed lumped parameter model of HRV, introduced earlier. Ten signals were generated in different physiological conditions. DFA coefficients alpha1, alpha2, and the Hurst exponent, were calculated. A clear disruption point was always observed. Modifications in sympatho-vagal activity yielded significant changes in alpha1 when compared to basal, but not in alpha2 or Hurst exponent. Modifications in non-nervous system mediated changes yielded significant differences only for peripheral resistance and heart period, only in alpha1. In conclusion, the analysis of the effect of changes in the regulatory system on the HRV chaotic/fractal indices can be analyzed using detailed lumped parameter models. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling and estimation of time-varying heart rate variability during stress test by parametric and non parametric analysis

    Publication Year: 2007 , Page(s): 29 - 32
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1878 KB) |  | HTML iconHTML  

    A methodological framework for simulating real-like HRV during stress test with controlled spectral properties has been developed with the purpose to assess SPWVD and time-variant AR analysis. For each method results have been evaluated computing the estimation error for LF and HF components during all the test (mean error of the order of 10% in all case) and a direct comparison based on the correlation between estimate and original ACF yields very high values (rhoWV=0, 99 and rhoAR=0, 94). In real data analysis bothmethods highlightan inversion of the relative spectral balance around the apex of exercise which passes from LF to HF prevalence. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cyclic variation in heart rate during sleep in four recordings of up to 13 years in elderly adults

    Publication Year: 2007 , Page(s): 33 - 35
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1849 KB) |  | HTML iconHTML  

    To characterize changes in nighttime cyclic variation in HR (CVHR) with advancing age in older adults, CVHR was quantified for N=56 adults with 2 Holter recordings 5 yrs apart (CHS1 and CHS 2) in the cardiovascular health study (CHS) and 2 overnight polysomnograms 5 yrs apart in the sleep heart health study (SHHS1 and SHHS2) using MatLab. Baseline age was 71plusmn3 yrs. The number of CVHR events was also normalized to time in bed (CVHR index). CVHR index did not change across recordings, but males had higher values (p=0.009). Mean HR increase during CVHR was similar in the first 3 recording but declined on the last (p<0.02). CVHR duration increased, but CHS1 vs. CHS2 and SHHS1 vs. SHHS2 were NS (rest, p<0.007). We conclude that CVHR is frequent at night in older adults, but results suggest an age-related trend towards decreased magnitude and longer durations of HR arousals, possibly due to the aging of the autonomic nervous system. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The mean firing rate of atrial fibrillation as estimated from the ECG evaluation using a biophysical model

    Publication Year: 2007 , Page(s): 37 - 40
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2173 KB) |  | HTML iconHTML  

    The correspondence between the firing rates of atrial myocytes during atrial fibrillation and the dominant frequencies observed in the Fourier spectra of the corresponding surface ECG signals was studied. The observations were based on signals simulated using a biophysical model of the atria and of the volume conduction effects of the thorax. Different substrates for AF were generated, each resulting in a different type of AF dynamics. The results indicate that the full Fourier spectrum yields more information on the complexity of a particular variant of AF than the analysis of just its dominant frequency. The same applies to analyzing the spectra of multiple leads rather using just single lead signals. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysing effects of implant dimensions on electrocardiograph: A modeling approach

    Publication Year: 2007 , Page(s): 41 - 44
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1588 KB) |  | HTML iconHTML  

    Modeling offers effective means of studying the effects of implant dimensions on the measured electrocardiograph (ECG) prior to any in vivo tests, and thus provides the designer with valuable information. Finite difference (FDM) and lead field approaches combined with cardiac activation models offer straightforward and effective methods for analyzing different ECG measurement configurations. In the present study such methods are applied in studying the effects of implant dimensions on the simulated ECG which describes an ectopic beat originating from the apex. The results indicated that the change in interelectrode distance has the largest effects on the ECG. Other parameters related implant dimensions have minor effect on the ECG. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 3D model of magnetohydrodynamic voltages: Comparison with voltages observed on the surface ECG during cardiac MRI

    Publication Year: 2007 , Page(s): 45 - 48
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1623 KB) |  | HTML iconHTML  

    The magnetohydrodynamic (MHD) effect generates voltages which distort the ECG obtained during cardiac MRI. Consequently, MHD voltages result in triggering problems for MR image acquisition. In addition, since the MHD effect is related to blood flow, analysis of it not only as interference, but also as a signal may provide useful blood flow information. Comsol Multiphysics modeling software was used to compute and model the MHD voltages in 3D. These voltages were compared with MHD voltages obtained experimentally from the subtraction of ECGs taken outside the MRI magnet from ECGs taken inside the magnet. The maximum MHD voltage magnitude for the experimental data was 0.2 mV and was 3.04 mV for the modeled data when calculated on the surface of the uniform volume conductor. By modeling MHD voltages in 3D, we can learn about their effect on the ECG during cardiac MRI. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling of heterogeneous electrophysiology in the human heart with respect to ECG genesis

    Publication Year: 2007 , Page(s): 49 - 52
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1600 KB) |  | HTML iconHTML  

    Heterogeneity of ion channel properties within human ventricular tissue determines the sequence of repolarization under healthy conditions. In this computational study, the impact of different extend of electrophysiological heterogeneity in both human ventricles on the ECG was investigated by a forward calculation of the cardiac electrical signals on the body surface. The gradients ranged from solely transmural, interventricular and apico-basal up to full combination of these variations. As long interventricular heterogeneities were neglected, the transmural gradient generated a positive T wave that was increased when apico-basal variations were considered. Inclusion of interventricular changes necessitated the incorporation of both transmural and apico-basal heterogeneities to reproduce the positive T wave. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determining risk factors for survival after LMCA stenosis with intelligent data analysis

    Publication Year: 2007 , Page(s): 53 - 56
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1490 KB) |  | HTML iconHTML  

    Coronary artery disease is one of the most frequent causes of premature deaths in Slovenia and also in most countries in the world. A ldquogold standardrdquo for treatment of left main coronary artery (LMCA) stenosis is still a surgical therapy; however percutanueous transluminal coronary angioplasty (PTCA) is much simpler for the patients and gives comparable short-term and mid-term results to surgical therapy. PTCA of LMCA stenosis is safe and technically demanding but long-term clinical outcomes are not yet defined. In this paper we present an intelligent data analysis method for inducing a decision tree that was able to outline some anticipated and also some relatively unexpected but useful risk factors for survival after PTCA. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Decision support system for the practical implementation of the Chronic Heart Failure guidelines: The MyHeart approach

    Publication Year: 2007 , Page(s): 57 - 60
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1722 KB) |  | HTML iconHTML  

    Chronic Heart Failure (CHF) is the major cause for hospitalization in adults in western societies, mainly due to decompensation of patients. Active prevention, diagnosis, and personalized treatment contribute to the stabilization of chronic patients and the reduction of events. The approach of the EU FP6 MyHeart project is to collect daily vital body signs on CHF patients in an easy and comfortable way. The data is processed via a decision support system (DSS) and the platform gives instant recommendations to the user. The system also sends the information to the professionals for a better follow-up. The designed DSS is based on Bayesian networks (BN) and combines the accepted standardized clinical guidelines with the most advanced monitoring data in daily routine, in order to provide individualized recommendations to the patient in a concrete situation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of teaching basic electrocardiographic concepts with and without ECGSIM, an interactive program for electrocardiography

    Publication Year: 2007 , Page(s): 61 - 64
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1499 KB) |  | HTML iconHTML  

    The electrocardiogram (ECG) is an important diagnostic tool in the management of cardiac disease. Currently, most methods of introducing electrocardiography in medical schools rely on books, papers, and clinical observation (classical method). As more interactive software become available, it would be instructive for students to learn the ECG this way. This study compares the effectiveness of teaching the basics of electrocardiography using the classical method versus an interactive program, ECGSIM. Thirty-five students were randomized into two groups (classical and ECGSIM) and were taught the basic concepts of the ECG. This study demonstrates that teaching electrocardiography using ECGSIM is superior to traditional methods alone, indicating a potentially large role for interactive programs in teaching electrocardiography. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Virtual heart: Simulation-based cardiac physiolgy for education

    Publication Year: 2007 , Page(s): 65 - 68
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1855 KB) |  | HTML iconHTML  

    An investigation into the technical feasibility of computer based interactive simulation of the heart was conducted. The project is currently at prototype development phase, which is focused on the development of a virtual heart organ. The prototype will be customized for clinical skills training for interventional cardiology and electrophysiology, as well as for general cardiology education. Further development will incorporate an interface for handling catheter insertion for cardiac ablation and pacing. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Use of body-surface potential mapping and computer model simulations for optimal programming of cardiac resynchronization therapy devices

    Publication Year: 2007 , Page(s): 69 - 72
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1495 KB) |  | HTML iconHTML  

    It has been proposed that by optimizing the timing of activation between the ventricles (V-V interval), with the aid of body-surface potential mapping (BSPM), the success rate of cardiac resynchronization therapy (CRT) devices could be improved. We recorded 120-electrode BSPM data and CT scans from two patients with implanted CRT devices and calculated, by means of electrocardiographic inverse solution, epicardial potentials and isochrones of activation for different V-V intervals. To gain better insight, we used a computer model of ventricular activation to simulate activation isochrones for CRT pacing. As a measure of inter-ventricular synchrony for a variety of V-V settings we used the area between the LV and RV percent surface activated curves. We have demonstrated that by aiming to minimize dyssynchrony in ventricular activation patterns, an optimal CRT pacing V-V interval can be selected. The computer model simulations provided a baseline measure by which our measure of synchrony can be evaluated. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Assessment of factors affecting accuracy and repeatability in semi-automated echocardiographic measurement of chamber volume using a physical phantom

    Publication Year: 2007 , Page(s): 73 - 76
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1494 KB) |  | HTML iconHTML  

    Three dimensional echocardiography offers the benefit of non-invasive measurement of chamber volume at the cost of increased effort of data handling. Automated or semi-automated image analysis may help to reduce manual effort but can embody assumptions and limitations which have a significant effect on results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Prognostic significance of electrocardiogram and cine magnetic resonance imaging parameters in patients with idopathic dilated cardiomyopathy

    Publication Year: 2007 , Page(s): 77 - 80
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1665 KB) |  | HTML iconHTML  

    Patients with idopathic dilated cardimyopathy (IDC) and reduced left ventricular function have a limited prognosis. Aim of this study was the evaluation of parameters of cardiac magnetic resonance imaging (CMRI) and ECG for prognosis. 149 patients with IDC were studied by CMRI for hemodynamic and late enhancement (LE) analysis and followed for a mean of 986 plusmn 588 days. QRS and QTc intervals were measured. In total we recorded 16 parameters including NYHA status, age and diabetes mellitus. Combined endpoint was cardiac death, sudden death (SCD) or rehospitalization for pump failure. We used a bootstrap approach over the cases combined with a stepwise parameter selection method to find the most relevant variables in a Cox proportional hazard model. We found that 3 parameters, namely QRS duration > 110 ms, left ventricular enddiastolic volume index, and left ventricular cardiac index were most predictive. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cardiac motion analysis from magnetic resonance imaging: Cine magnetic resonance versus tagged magnetic resonance

    Publication Year: 2007 , Page(s): 81 - 84
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1628 KB) |  | HTML iconHTML  

    The objective of this work is to compare the results obtained from the motion analysis of tagged vs. CINE MR sequences when using spatio-temporal non-rigid registration techniques based on pixel intensity. Those techniques have been previously validated on tagged MR images. Moreover, registration algorithms have been applied to MR CINE sequences to obtain radial displacement and strain parameters demonstrating its usefulness to quantify regional myocardial function. Tagged and CINE MR short axis sequences from 10 subjects were examined. Four segments were manually selected in both the tagged MR and CINE sequences. Automatic estimation of the myocardial motion field was performed using a consecutive non-rigid registration algorithm based on a semilocal Bspline parametric model. Finally, a statistical analysis was applied to compare the systolic displacement and strain estimations from both types of sequences. An important discrepancy between results obtained from tagged MR based strain analysis and CINE MR has been found. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Assessment of left atrial function using multi-slice CT images

    Publication Year: 2007 , Page(s): 85 - 88
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1813 KB) |  | HTML iconHTML  

    The function of left atrium can be accurately estimated non-invasively using 4D CT cardiac images. A self-developed image analysis program will first reconstruct 3D volume of heart. Then, one may re-sample images for accurately deleting the 4 pulmonary veins from the atrium and set the boundary. With the prior processed information, the active contour methodology and seed regional growth methodology were implemented to delineate the atrial contour. With a calibration standard of 500 ml saline with contrast medium in bag, both methods were able to estimate volume within 5% of error. Thirty sets of patientpsilas CT cardiac images that were acquired at 30% and 90% of RR interval. The dimension of pulmonary veins and the left atrial volume was evaluated. The contractility of pulmonary vein and the ejection fraction (EF) of atrium was calculated. The result shows that the left atrium with a larger volume will have a poor ejection fraction. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Comparison of three methods to estimate regional wall motion on the Evalechocard database of echocardiographic image sequences

    Publication Year: 2007 , Page(s): 89 - 92
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1485 KB) |  | HTML iconHTML  

    The objective of this paper is to propose a framework in order to make the comparison of image processing algorithms effective. This framework was applied to three methods developed for automated regional wall motion scoring and they were compared to a reference scoring on a database of echocardiographic images (Evalechocard). Firstly, 200 annotated echocardiograms on hundred patients were used for the training stage; secondly the algorithms were blinded tested on 100 additional echocardiograms. Results obtained by the three methods are presented, using different metrics to compare them. This evaluation procedure enables a real progress in the assessment of each method and helps to understand its limits and its potentialities. Test results have shown the difficult cases and could be further used to improve the methods. Moreover the annotated database is now open to any research group who wants to test its own methods. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Denoising cyclostationary framework for enhanced Electrocardiogram analysis

    Publication Year: 2007 , Page(s): 93 - 96
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1443 KB) |  | HTML iconHTML  

    We present a novel two module scheme for efficient analysis of noisy Electrocardiogram (ECG) signals. The first module consists of a segmentation algorithm which uses cyclostationary analysis for the detection of a single heart beat or cycle (P wave-QRS complex-T wave). The time domain cyclostationary (CS) algorithm exploits the statistical properties of the recorded periodic ECG signal and does not use any prior knowledge about signal morphology. Using the obtained cycle length the next module uses repeated applications of Principal Component Analysis (PCA) to reduce multiple additive noises from the multi trial and multi channel recorded ECG signals. PCA has been used for noise reduction in ECG but the method of repeated applications of PCA is novel. In this study, PCA was applied in 2 stages. In the first stage, PCA was applied to multi-channel ECG signals from one trial. The output ECG signals from the first stage were used in the second stage, where PCA was applied to multi-trial ECG signals from a single channel. The proposed scheme was tested with the 12-lead ECG signals from PTB Diagnostic database (National Metrology Institute of Germany) provided on physionet website which showed significant improvement in Signal to Noise ratio. We suggest that this simple scheme can be used for automatic analysis of noisy ECG signals where the extraction and denoising of single heart beat provide enhanced physiological features which enables better clinical interpretation of cardiovascular functionalities. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wavefront detection from intra-atrial recordings

    Publication Year: 2007 , Page(s): 97 - 100
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1508 KB) |  | HTML iconHTML  

    The present study deals with detection of intra-atrial wavefronts from atrial activation times in adjacent bipolar electrograms. A statistic of the delays within each wave-front was calculated and served as a basis for quantifying the wavefront consistency as well as the propagation of the electrical activity along the catheter. The database consisted of 19 patients for which five electrograms were recorded simultaneously during 10 s. The analysis resulted in 38plusmn2 complete wavefronts per patient, i.e., wavefronts consisting of one activation from each recording site. Two parameters were evaluated for quantifying wavefront consistency, which together with the propagation profile well reflect the overall wavefront timing. In most cases, electrical activity was observed first in the high septal right atrium, and then spread along the catheter. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.