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

Using 49 capacitive-coupled electrodes, mattress-type harness was developed to obtain posterior body surface potential map (P-BSPM) in dressed individuals. The aim of this study was to investigate how valuable information P-BSPM could provide, especially in discrimination of old myocardial infarction (OMI). P-BSPM of 59 individuals were analyzed; 23 normal control, 11 right bundle branch block (RBBB), 3 left bundle branch block (LBBB) and 19 OMI patients. Principal component analysis and linear hyper-plane approach were used to evaluate diagnostic performance. The axes of P-BSPM vector potential corresponded well with 12-lead electrocardiogram. During QRS, the end point of P-BSPM vector potential demonstrated characteristic clockwise rotation in RBBB, and counterclockwise rotation in LBBB patients. In OMI, initial negativity on P-BSPM during QRS was more frequently located at lower half, and also stronger in patients with inferior myocardial infarction (MI). The area under the receiver-operating characteristic curve of P-BSPM during QRS in diagnosing overall OMI, anterior MI, and inferior MI was 0.83 (95% confidence interval, 0.70-0.97), 0.71 (0.47-0.94), and 0.98 (0.94-1.0), respectively (P = 0.022 for anterior vs inferior MI groups). In conclusion, the novel P-BSPM provides detailed information for cardiac electrical dynamics and is applicable to diagnosing OMI, especially inferior myocardial infarction.
Adult ; Aged ; Area Under Curve ; Body Surface Potential Mapping/instrumentation/*methods ; Bundle-Branch Block/diagnosis ; Electrocardiography ; Electrodes ; Humans ; Male ; Middle Aged ; Myocardial Infarction/diagnosis ; Principal Component Analysis ; ROC Curve

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

In order to control real-time sampling and achieve smooth scroll wave in the epicardial mapping system, which has 128 channels and a sampling rate of 2kHz/channel, we have designed a user interface using Direct-Draw in cooperation with multiple-thread technology and extracting method. This method has proven to be feasible in animal experiment.
Algorithms ; Animals ; Artificial Intelligence ; Body Surface Potential Mapping ; methods ; Electrophysiologic Techniques, Cardiac ; instrumentation ; methods ; Pericardium ; physiology ; Signal Processing, Computer-Assisted ; instrumentation ; Software

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.

Body Surface Potential Mapping ; Electrocardiography ; Humans ; Wolff-Parkinson-White Syndrome ; diagnosis ; physiopathology

OBJECTIVETo explore the effect of reference point on the potential distribution of normal cardioeleclric field of healthy individuals.

METHODSTwo different reference points including central terminal and right forehead were applied to record electrocardiogram simultaneously from 15 testing points (V(1)-V(6), V(7)-V(9), V(3R)-V(8R)) of Wilson lead (RL) and the same testing points (HV(1)-HV(9), HV(3R)-HV(8R)) of head-chest (HC) lead around the torso of healthy individuals. Chi-square test was performed to observe statistical difference between the HCECGs and RLECGs according to different shapes of QRS and T waves.

RESULTSAmong 120 healthy individuals, deformed ECGs appeared in V(1) and HV(3R)-HV(8R) leads, with 20% (24/120) inverted T wave in V(1) lead, 100% (120/120) in V(3R)-V(8R) leads, wide or deep Q wave 100% (120/120) in V(4R)-V(8R) leads. However, in the corresponding HC-lead system, T waves were all positive, and QRS waves were upright as the pattern of rs, RS or qRs. There was statistical difference in the form of ECG between V(1), V(3R)-V(8R) of Wilson lead and the corresponding HC-lead (P<0.05). The distribution of normal cardioeleclric field related to QRS-T wave was of all-round outward shape by HC-lead, and of roughly bipolar shape by Wilson lead for inverted QRS-T wave on the right thoracic surface.

CONCLUSIONThe normal distribution of electrocardial field is determined by the potential of the reference point. The forehead of HC-lead seems to be better than the central terminal as the reference point of the lead system.

Adolescent ; Adult ; Body Surface Potential Mapping ; methods ; standards ; Chi-Square Distribution ; Female ; Heart ; physiology ; Humans ; Male ; Middle Aged ; Reference Values ; Young Adult

BACKGROUNDSubstrate modification guided by CARTO system has been introduced to facilitate linear ablation of ventricular tachycardia (VT) after myocardial infarction (MI). However, there is no commonly accepted standard approach available for drawing these ablation lines. Therefore, the aim of the present study was to practically refine this time consuming procedure.

METHODSSubstrate modification was performed in 23 consecutive patients with frequent VTs after MI using the CARTO system. The initial target site (ITS) for ablation was identified by pace mapping (PM) during sinus rhythm and/or entrainment pacing (EM) during VT. According to the initial target site, two approaches were used. The initial target site in approach one has a similar QRS morphology as VT and an interval from the stimulus to the onset of QRS complex (S-QRS) of = 50 ms during PM in sinus rhythm or a difference of the post pacing interval and VT cycle length = 30 ms during concealed entrainment pacing of VT; The initial target site in approach two has an similar QRS morphology as VT and an S-QRS of < 50 ms during PM in sinus rhythm.

RESULTSOverall, 50 lines were performed with a length of (35 +/- 11) mm. Procedure time averaged (232 +/- 56) minutes, fluoroscopy time (10 +/- 8) minutes. Sixteen patients were initially involved into approach one. After completion of 3 +/- 1 ablation lines, no further VT was inducible in 13 patients. The remaining 3 patients were switched to use the alternative approach. However, in none of them the alternative approaches were successful. Approach two was initially used in 7 patients. After completion of 3 +/- 1 ablation lines, no further VT was inducible in only 2 patients. The remaining 5 patients were switched to approach one, which resulted in noninducibility of VT in 4 of them. The initial successful rate was significantly higher in the group of approach one compared to that in the group of approach two (13/16 patients vs 2/7 patients, P = 0.026).

CONCLUSIONSThe approach for substrate modification of VT after MI can be optimized by identifying the appropriate initial target site with specific characteristics within the zone of slow conduction. The refined approach may facilitate linear ablation of VT, and further reduce the procedure and fluoroscopy time.

Aged ; Body Surface Potential Mapping ; instrumentation ; methods ; Catheter Ablation ; methods ; Electrocardiography ; Female ; Humans ; Male ; Middle Aged ; Myocardial Infarction ; complications ; Surgery, Computer-Assisted ; methods ; Tachycardia, Ventricular ; physiopathology ; surgery

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

Atrial fibrillation (AF) is a complex and dangerous arrhythmia. The treatment method is still unefficient because of its unknown mechanism. The purpose of our research is to detect the electrical activity on the atria surface and therefore find the optimal technique to characterize AF for clinical application. All kinds of maps are presented clearly and the activity of sinus or AF rhythm can be seen quite differently. The active isopotential map can display the dynamic electrical conduction of the atrium as a movie. Sequentially the vectorgraph shows the direction of depolarization at every moment. Finally statistical results are also very useful for analysis on AF. Statistics of exciting frequency and correlation area show great difference in various channels during AF. "Source" or "sink" may be estimated by interval variance statistics. This study demonstrates the flexibility of the system in AF research. The statistical results can also be adopted to clearly express the characteristics of AF.
Animals ; Atrial Fibrillation ; diagnosis ; physiopathology ; Body Surface Potential Mapping ; methods ; Dogs ; Electrocardiography, Ambulatory ; Electrodiagnosis ; methods ; Pericardium ; physiopathology ; Swine