The endeavors to solve the inverse problem of electrocardiography embody the approach to calculate the epicardial potentials using the measured body-surface-potential distribution; it is important for pathology and very useful for clinical application. In this paper, we construct the 2D human torso model using the FEM method and solve the forward problem. In the constructed state-space equations, and the relationship between the body surface potentials and epicardial potentials in the FEM torso model is the measurement equation, and the relationship of the adjacent states is the state process equation. To solve the problem of uncertainty of the parameters, we design the likelihood function and introduce the Expectation Maximization (EM) algorithm. Step E (Expectation) estimates the parameters using the Kalman filter; step M (Maximization) re-estimates the parameters using the likelihood functions, step E and step M iterate. Simulations of the whole process show that EM algorithm leads to better convergence of the solutions than does the traditional Kalman filtering, and the relative errors are much smaller than before.
Algorithms ; Body Surface Potential Mapping ; methods ; Finite Element Analysis ; Humans ; Models, Cardiovascular ; Signal Processing, Computer-Assisted

OBJECTIVETo observe whether there was difference between the head-chest leads electrocardiogram (HCECGs) and routine lead electrocardiogram (RLECGs) in the manifest accessory pathways in patients with Wolff-Parkinson-White syndrome.

METHODSHCECGs and RLECGs were recorded simultaneously in patients with Wolff-Parkinson-White syndrome, whose manifest accessory pathways had been confirmed by radiofrequency catheter ablation and intra-cardiac electrophysiology according to the same standard set beforehand. The diagnosis of pathways location was made by analysis of each HCECG and RLECG by two senior physicians in clinical electrophysiology. The diagnostic accuracy of the HCECGs and RLECGs was evaluated by the comparison with that of the intra-cardiac electrophysiology. The delta wave size was also compared between HCECGs and RLECGs.

RESULTSThe diagnostic accuracy in the manifest accessory pathways was 86.2% (50/58) in RLECGs, and 84.4% (49/58) in HCECGs in the 58 patients with Wolff-Parkinson-White syndrome, showing no significant difference between them (P > 0.05), but each delta wave in HCECG was more evident than that in RLECG.

CONCLUSIONHCECG and RLECG both have high diagnostic accuracy in the manifest accessory pathways in patients with Wolff-Parkinson-White syndrome.

Surface Laplacian of the body surface potential (Laplacian ECG--LECG) is a new approach to resolve spatially distributed bioelectrical source. In this paper, we discussed an LECG sensor which integrated triple concentric ring electrodes and signal adjustor on a printed board. The LECG is measured directly by this sensor. The frequency, amplitude and phase of the power line interference were detected by a nonlinear adaptive filter so that interference was eliminated. The wavelet shrinking technique was used to eliminate the rest of random noise. And we got the high quality LECG signal. It laid the foundation for heart disease diagnosis.
Algorithms ; Body Surface Potential Mapping ; methods ; Electrocardiography ; methods ; Electrodes ; Humans ; Signal Processing, Computer-Assisted

In this article, some details about the parameter optimization of body surface Laplacian electrodes are presented theoretically and practically. The influence of these parameters on the performance of the electrodes is studied to derive some rules which have to be obeyed during the design. An evaluation routine based on relative error analysis and the noise level of amplifier is prompted. Furthermore, the paper particularly indicates that, it would be helpful to reduce the relative error when assuming that the effective radius b is equal to the inner radius r(i) of the ring electrode. Finally, we suggest that in the presence of weak bioelectrical signals, the effective radius of the electrodes should be reasonably increased in order to improve signal-to-noise ratio (SNR).
Body Surface Potential Mapping ; methods ; Electric Impedance ; Electrodes ; Humans ; Signal Processing, Computer-Assisted

In this paper, a method based on the convex hull algorithm is presented for extracting modelling data from the locations of catheter electrodes within a cardiac chamber, so as to create a 3-D model of the heart chamber during diastole and to obtain a good result in the 3-D reconstruction of the chamber based on VTK.
Algorithms ; Body Surface Potential Mapping ; methods ; Catheter Ablation ; Humans ; Image Processing, Computer-Assisted ; methods

We put forward a new concept of software oversampling mapping system for electrocardiogram (ECG) to assist the research of the ECG inverse problem to improve the generality of mapping system and the quality of mapping signals. We then developed a conceptual system based on the traditional ECG detecting circuit, Labview and DAQ card produced by National Instruments, and at the same time combined the newly-developed oversampling method into the system. The results indicated that the system could map ECG signals accurately and the quality of the signals was good. The improvement of hardware and enhancement of software made the system suitable for mapping in different situations. So the primary development of the software for oversampling mapping system was successful and further research and development can make the system a powerful tool for researching ECG inverse problem.
Body Surface Potential Mapping ; instrumentation ; Electrocardiography ; instrumentation ; Equipment Design ; Humans ; Signal Processing, Computer-Assisted ; instrumentation ; Software

Although complex fractionated electrogram (CFE) is known to be a target for catheter ablation of fibrillation, its physiological meaning in fibrillation wave-dynamics remains to be clarified. We evaluated the spatiotemporal relationships among the parameters of fibrillation wave-dynamics by simulation modeling. We generated maps of CFE-cycle length (CFE-CL), local dominant frequency (LDF), wave break (WB), and phase singularity (PS) of fibrillation in 2-dimensional homogeneous bidomain cardiac modeling (1,000 x 1,000 cells ten Tusscher model). We compared spatiotemporal correlations by dichotomizing each maps into 10 x 10 lattice zones. In spatial distribution, WB and PS showed excellent correlation (R = 0.963, P < 0.001). CFE-CL had weak correlations with WB (R = 0.288, P < 0.001), PS (R = 0.313, P < 0.001), and LDF (R = -0.411, P < 0.001). However, LDF did not show correlation with PS or WB. PSs were mostly distributed at the periphery of low CFE-CL area. Virtual ablation (5% of critical mass) of CFE-CL < 100 ms terminated fibrillation at 14.3 sec, and high LDF ablation (5% of critical mass) changed fibrillation to organized tachycardia, respectively. In homogeneous 2D fibrillation modeling, CFE-CL was weakly correlated with WB, PS, and LDF, spatiotemporally. PSs are mostly positioned at the periphery of low CFE-CL areas, and virtual ablation targeting low CFE-CL regions terminated fibrillation successfully.
Algorithms ; Atrial Fibrillation/*physiopathology ; Body Surface Potential Mapping ; Catheter Ablation ; *Electrocardiography ; Electrodes ; Heart Atria/physiopathology ; Humans ; *Models, Biological

PURPOSE: Right ventricular (RV) infarction is associated with increased morbidity and mortality in patients with acute inferior wall myocardial infarction (MI). A 12-lead electrocardiogram (ECG) has a poor tendency to identify RV involvement. Our objective was to evaluate the diagnostic accuracy of 80-lead body surface mapping (BSM) for RV infarction and to compare diagnostic accuracy of 12-lead ECG criteria and 80-lead BSM for RV infarction in patients with acute inferior wall MI. METHODS: Between September 2002 and January 2003, 96 patients visited to our emergency center with AMI. All standard initial 12-lead ECG and 80-lead BSM were examined and compared with angiographic and echocardiographic findings. RESULTS: Thirty-one patients were confirmed as inferior wall MI. With the use of exclusion criteria, sixteen patients included in this study. RV infarction accompanied in 5 patients of these 16 patients. BSM showed a high sensitivity (60%), specificity (82%), high positive and negative predictive values (60%, and 82%, respectively), and high diagnostic accuracy (75%) in diagnosing RV infarction in patients with acute inferior wall MI. BSM showed increase in the sensitivity for RV infarction from 40% to 60% when compared with the 12-lead ECG. CONCLUSION: The 80-lead BSM is a more useful test in diagnosing RV infarction in patients with acute inferior wall
Body Surface Potential Mapping* ; Echocardiography ; Electrocardiography* ; Emergencies ; Heart Ventricles ; Humans ; Infarction ; Inferior Wall Myocardial Infarction ; Mortality ; Myocardial Infarction* ; Sensitivity and Specificity

PURPOSE: A 12-lead ECG is only 50% sensitive for the detection of an acute myocardial infarction (AMI). The majority of leads for optimal classification of an AMI probably lie outside the area covered by the 6 precordial leads. Thus, body surface potential mapping (BSPM) may be more helpful in diagnosing AMI, because a large thoracic area is sampled. METHODS: Two hundred sixty-eight consecutive patients with ischemic-type chest pain, who visited our emergency medical center from August 2002 to January 2003, were recruited prospectively. A 12-lead ECG and an 80-lead BSPM were recorded at presentation. Cardiac markers were measured. Acute myocardial infarction was defined as 1) chest pain with a duration greater than 20 minutes and, 2) elevated cardiac enzyme. The diagnoses of the 12-lead ECGs and the BSPM algorithms were categorized into two subgroups, AMI and non-AMI, and were compared. RESULTS: Of the 268 patients, 81 patients (30.2%) were confirmed as having an acute myocardial infarction. The 12-lead ECGs identified 32 patients with AMI (sensitivity 39.5%, specificity 93.0%), and the BSPM algorithm identified 56 patients with AMI (sensitivity 69.1%, specificity 85.6%). Patients with a positive BSPM diagnosis were much more likely to have AMI (odds ratio 13.3, 95% Confidence interval 7.1~24.8) than patients with a positive 12-lead ECG diagnosis. Thirty AMI patients that had not been detected with 12-lead ECGs were detected with 80-lead BSPMs (sensitivity 61.2%, specificity 87.9%). CONCLUSION: When compared with the 12-lead ECG, the BSPM algorithm has a higher sensitivity for detection of AMI, particularly in patients presenting with chest pain and nondiagnostic ECG changes. The use of the BSPM algorithm in such patients may lead to earlier detection of an AMI.
Body Surface Potential Mapping* ; Chest Pain ; Classification ; Diagnosis* ; Electrocardiography ; Emergencies ; Humans ; Myocardial Infarction* ; Prospective Studies ; Sensitivity and Specificity

Based on a 3-D inhomogeneous simulative body torso model, the influence of various boundary conditions on inverse recovered epicardial potential maps (EPM) was studied by boundary element method (BEM). The result shows that the precision of EPM calculated under incomplete boundary conditions will meet the clinical requirements, as long as the incomplete boundary conditions still contain the extremum area which often appears at the breast area.
Action Potentials ; Algorithms ; Body Surface Potential Mapping ; Computer Simulation ; Electrocardiography ; Heart ; physiology ; Humans ; Mathematics ; Membrane Potentials ; physiology ; Microcomputers ; Models, Cardiovascular