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Results for “Body Surface Potential Mapping”

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PubMed2002

Circular mapping catheter entrapment in the mitral valve apparatus: a previously unrecognized complication of focal atrial fibrillation ablation.

Radiofrequency catheter ablation of focal atrial fibrillation triggers within the pulmonary veins is a rapidly developing therapy that relies on both recent technologies and evolving techniques. We describe the entrapment of a circular mapping catheter within the mitral valve apparatus after transseptal catheterization and mapping of the left atrium and pulmonary veins. The occurrence of this previously unreported complication stresses the need for continual monitoring and reporting of adverse effects from new devices and procedures to better inform patients and physicians of the benefits and risks of electrophysiologic interventions.

Atrial Fibrillation↗
PubMed2006

Hybrid therapies for ventricular arrhythmias.

In recent years several trials demonstrated the efficacy of implantable cardioverter-defibrillation (ICD) therapy in reducing cardiac and total mortality in patients affected by rapid ventricular tachycardia (VT) and/or ventricular fibrillation. Nevertheless, ICD do not prevent arrhythmia recurrences, thus being a palliative and not a curative treatment modality. The tolerance to ICD therapy varies greatly, and within individuals, this leading to a nonuniform acceptance of this form of therapy. The very frequent occurrence of VT, defined as an arrhythmic storm, may be a life threatening condition. The majority of ICD patients is under antiarrhythmic drug therapy, to reduce episodes of VT or to make antitachycardia pacing more effective by slowing the tachycardia rate. Drug therapy, however, may cause additional problems, and does not represent the optimal solution. The prevention of VT and/or ventricular fibrillation episodes and excessive ICD therapy, remains a worthwhile goal. Radiofrequency catheter ablation (RFCA) is a curative approach, and can be expected to reduce the frequency of recurrent VT episodes in the majority of patients. The combination of these treatment modalities (ICD and RFCA) is often described as hybrid therapy, implying that the two treatments act providing some form of synergism. In experienced centers, RFCA is now performed, regardless of whether the VT rate is rapid and/or is hemodynamically unstable. Newer mapping and ablation techniques are now available, enhancing the acute success rate of the procedure. In this review the most recent application of VT catheter ablation and the use of advanced mapping and ablation techniques will be discussed.

Body Surface Potential Mapping↗
PubMed2006

Imaging techniques in cardiac electrophysiology.

Modern cardiac electrophysiology procedures include catheter-based arrhythmia ablation and transvenous device implantation, which are highly dependent on accurate, real-time cardiac imaging. With the realization that anatomic structures are critical to successful electrophysiologic procedures, accurately defining a patient's cardiac anatomy has become more important. Fluoroscopy allows for 2D imaging of cardiac structures in real-time, and is used to guide catheter and lead placement, but does not allow for visualization of soft tissues. Intracardiac echocardiography allows for both direct visualization of anatomic structures within the heart and real-time imaging during catheter placement. Despite advances in intracardiac echocardiography catheters that allow for larger windows, the ability to accurately delineate anatomic structures depends on the patient's anatomy and operator experience. Neither of these techniques allows for electrical mapping of the heart; however, both anatomic and electrical intracardiac mapping can be achieved with advanced mapping systems. These systems allow for real-time catheter localization, help elucidate cardiac anatomy, evaluate electrical activation during arrhythmias and guide catheter placement for deliverance of radiofrequency current. More recently, 3D cardiac computed tomography has been used to accurately define intracardiac anatomy; however, catheter tracking and electrical mapping cannot be performed by computed tomography. Mapping systems are now being merged with computed tomography images to produce an accurate anatomic and electrical map of the heart to guide catheter ablations. The objective of this paper is to describe the current imaging and mapping techniques used in electrophysiologic procedures.

Body Surface Potential Mapping↗
PubMed1997

Generalized eigensystem techniques for the inverse problem of electrocardiography applied to a realistic heart-torso geometry.

We have previously proposed two novel solutions to the inverse problem of electrocardiography, the generalized eigensystem technique (GES) and the modified generalized eigensystem technique (tGES), and have compared these techniques with other numerical techniques using both homogeneous and inhomogeneous eccentric spheres model problems. In those studies we found our generalized eigensystem approaches generally gave superior performance over both truncated singular value decomposition (SVD) and zero-order Tikhonov regularization (TIK). In this paper we extend the comparison to the case of a realistic heart-torso geometry. With this model, the GES and tGES approaches again provide smaller relative errors between the true potentials and the numerically derived potentials than the other methods studied. In addition, the isopotential maps recovered using GES and tGES appear to be more accurate than the maps recovered using either SVD and TIK.

Animals↗
PubMed2002

Information on heart repolarization changes obtained from body surface ECG potentials.

Possibility to obtain information about local changes of heart repolarization from body surface potentials was studied on a model. Activation-recovery intervals (ARI) in surface ECG leads were tested as indicators of changed repolarization in the underlying myocardium. ECG signals corresponding to activation of myocardium with normal and changed action potential duration were simulated on the surface of a realistic inhomogeneous torso. ARI intervals were derived from all ECG signals and displayed as surface ARI maps. Results suggest that shortening and prolongation of action potentials in anterior myocardial regions can be visible in corresponding areas on surface ARI maps while only prolongation in postero-lateral regions can be observed. Reproducibility of ARI maps was checked on real measurements using 63 and 192 surface ECG leads. Obtained ARI maps exhibited acceptable reproducibility with correlation of 0.73 to 0.87. Based on the model and experimental results it is hoped that ARI maps can give some insight into the myocardium repolarization and help to recognize tissue with changed properties, primarily in heart regions underlying the anterior chest.

Body Surface Potential Mapping↗
PubMed2006

Feasibility of the transseptal approach for fast and unstable left ventricular tachycardia mapping and ablation with a non-contact mapping system.

BACKGROUND: Radiofrequency ablation of fast and unstable left ventricular tachycardia (VT) usually requires non-contact mapping. The procedure is usually performed by a retrograde-transaortic route, requiring a double femoral artery puncture, for the 9F multielectrode catheter and the 7F ablation catheter which are advanced through the aorta and aortic valve into the left ventricle (LV). Reported limitations of the procedure are due to the stiffness of the balloon catheter, particularly in patients with tortuous peripheral arteries, atherosclerotic aorta, or with aortic stenosis. The aim of our study was to test the feasibility and assess the safety of a transseptal approach for left VT non-contact mapping and ablation. MATERIALS AND METHODS: Ten patients with multiple cardiac defibrillator shocks because of fast and unstable VT were selected for non-contact mapping and ablation. After a double transseptal puncture the multielectrode catheter (Ensite Array, St. Jude Medical) was advanced through a standard 10F introducer to a stable position in the LV apex over a 260 cm length 0.035 J-tip guidewire. The ablation catheter (Celsius Thermo-cool, Biosense Webster) was then inserted through the second 8F introducer. Twenty-five monomorphic sustained ventricular tachycardia were induced and ablated at the level of the diastolic pathway or exit point revealed by unipolar isopotential mapping. The total procedural and fluoroscopy times were 209 +/- 32 min and 28.5 +/- 9.27 min, respectively, which were comparable to those described with the traditional retrograde-transaortic approach. No major complication related with the transseptal approach were reported. CONCLUSION: A transseptal approach can be a feasible and effective alternative approach for mapping and ablation of fast and unstable left VT with a non-contact mapping system.

Aged↗
PubMed2003

Imaging electrocardiographic dispersion of depolarization and repolarization during ischemia: simultaneous body surface and epicardial mapping.

BACKGROUND: Myocardial ischemia creates abnormal electrophysiological substrates that result in life-threatening ventricular arrhythmias. Identifying patients at risk of such abnormalities by use of body surface electrical measures is controversial. We investigated the sensitivity of torso measures, recorded simultaneously with epicardial electrograms, to changes in dispersion of depolarization and repolarization during localized ventricular ischemia. METHODS AND RESULTS: Ventricular epicardial electrograms were recorded from 5 anesthetized pigs with a 127-electrode sock. A controllable suture snare was used to ligate the left anterior descending coronary artery (LAD). The chest was reclosed, and a vest with 256 ECG electrodes was fitted to the torso. Simultaneous arrays of epicardial electrograms and torso ECGs were recorded during LAD occlusion and reperfusion. Activation-recovery intervals (ARIs), QTu and RTu dispersion (where u indicates upstroke), and QRST integrals were calculated, and these data were fitted to anatomically customized computational models of the swine ventricular epicardium and torso. LAD occlusion caused the epicardial ARI dispersion to steadily increase, whereas the location of shortest ARI shifted from the posterobasal ventricular tissue (control) to the anteroapical myocardium, distal to the suture snare. These changes were associated with a steady increase in the torso RTu dispersion as the shortest RTu interval moved from the right shoulder (control) to the sternum. QTu and RTu dispersion determined from the 12-lead ECG did not consistently reflect the myocardial changes. CONCLUSIONS: Although changes in myocardial repolarization dispersion resulting from localized ischemia are not reliably reflected in temporal indices derived from the 12-lead ECG, they can be readily identified with high-resolution torso ECG mapping.

Animals↗
PubMed1995

[Body surface mapping in diagnosing the severity of left ventricular hypertrophy].

Body surface mapping is constructed from numerous electrocardiographic data, obtained from many lead points distributed over the entire thorax. It is generally accepted that the electrocardiographic features of ventricular hypertrophy consists of increase of voltage and prolongation of conduction time. In this report, the usefulness of body surface mapping in diagnosing the quantitative evaluation of left ventricular hypertrophy is reviewed. Finally, we attempted to diagnosis the severity of repolarization abnormalities from QRST isointegral map of patients with left ventricular hypertrophy.

Body Surface Potential Mapping↗
PubMed1984

[Effects of heart rate on body surface potential distribution in patients with atrial pacemaker].

Nine patients of sick sinus syndrome with atrial programmable pacemaker (3 males and 6 females, aged from 53 to 72 years) were studied to assess the effect of heart rate on the body surface potential distribution. Body surface maps (87 lead points) and M-mode echocardiograms were recorded at 20-beat increments of heart rate from 60 to 140 beats/min during atrial pacing. The potential changes of R and S voltages were evaluated quantitatively and were correlated with the changes of echocardiographically measured left ventricular dimension. As the heart rate increased, left ventricular dimension in end-diastole (LVDd) decreased gradually (Table 1), and a significant decrease was observed when the heart rate increased from 80 to 100 beats/min and from 100 to 120 beats/min, respectively, (p less than 0.05). With a decrease in LVDd, the distance between the left ventricular posterior wall and the anterior chest wall decreased and the left ventricular wall increased in its thickness. These changes, however, were not statistically significant. With an increase in the heart rate, R voltages decreased gradually in the left lateral chest and the sum of R voltages (sigma R) of six lead points in the left lateral chest including leads V5-6 decreased significantly when the heart rate increased from 60 to 100 beats/min and from 80 to 120 beats/min, respectively (p less than 0.02) (Table 2). On the other hand, R voltages remained unchanged in the left anterior chest during atrial pacing, then the sum of R voltages of six lead points in the left anterior chest including leads V2-4 and the sum of R voltages of 87 lead points did not show any significant changes (Table 2). An increase in the absolute value of S voltages was observed in the left anterior chest and the sum of S voltages of six lead points in the left anterior chest including leads V2-4 increased when the heart rate increased from 60 to 100 beats/min and from 80 to 120 beats/min, respectively (p less than 0.1) (Table 3) A decrease of R voltages in the left lateral chest was consistent with the reduction in LVDd (p less than 0.005). It is concluded that the changes in body surface QRS amplitudes during atrial pacing are related to those in the left ventricular dimension and that R voltages in the left lateral chest are fairly sensitive to see the changes in LVDd in cases with no abnormal wall motion of the left ventricle.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1995

Three-dimensional simulation of epicardial potentials using a microcomputer-based heart-torso model.

Previous cardiac simulation studies have focused on simulating the activation isochrones and subsequently the body surface potentials. Epicardial potentials, which are important for clinical applications as well as for electrocardiography inverse problem studies, however, have usually been neglected. This paper presents a procedure of simulating epicardial potentials using a microcomputer-based heart-torso model with real geometry. The heart model developed earlier which was composed of more than 60,000 cell units was used in this study. To simulate the epicardial potentials, an epicardial surface model which enclosed the whole heart was constructed. The heart model, together with the epicardial surface model, are mounted in an inhomogeneous human torso model. Electric dipoles, which are proportional to the spatial gradient of the action potential, are generated in all cell units. These dipoles give rise to a potential distribution on the epicardial surface, which is calculated by means of the boundary element method. The simulated epicardial potential maps during a normal heart beat and in patients with left bundle branch block (LBBB) are in close agreement with those reported in the literature.

Action Potentials↗