BACKGROUND Spatial resolution in cardiac activation maps based on voltage measurement is limited by far-field interference. Precise characterization of electrical sources would resolve this limitation; however, practical charge-based cardiac mapping has not been achieved. METHODS A prototype algorithm, developed from first principles of electrostatic field theory, derives charge density (CD) as a spatial representation of the true sources of the cardiac field. The algorithm processes multiple, simultaneous, noncontact voltage measurements within the cardiac chamber to inversely derive the global distribution of CD sources across the endocardial surface. RESULTS Comparison of CD to an established computer-simulated model of atrial conduction demonstrated feasibility in terms of spatial, temporal, and morphologic metrics. Inverse reconstruction matched simulation with median spatial errors of 1.73 mm and 2.41 mm for CD and voltage, respectively. Median temporal error was less than 0.96 ms and morphologic correlation was greater than 0.90 for both CD and voltage. Activation patterns observed in human atrial flutter reproduced those established through contact maps, with a 4-fold improvement in resolution noted for CD over voltage. Global activation maps (charge density-based) are reported in atrial fibrillation with confirmed reduction of far-field interference. Arrhythmia cycle-length slowing and termination achieved through ablation of critical points demonstrated in the maps indicates both mechanistic and pathophysiological relevance. CONCLUSION Global maps of cardiac activation based on CD enable classification of conduction patterns and localized nonpulmonary vein therapeutic targets in atrial fibrillation. The measurement capabilities of the approach have roles spanning deep phenotyping to therapeutic application. TRIAL REGISTRATION ClinicalTrials.gov NCT01875614. FUNDING The National Institute for Health Research (NIHR) Translational Research Program at Royal Papworth Hospital and Acutus Medical.

BACKGROUND:The relationship between insulin resistance, dyslipidemia, HIV infection, and antiretroviral therapy remains unclear, and the atherogenic nature of lipid and lipoprotein profiles in HIV-infected patients has not been fully characterized.METHOD:We measured plasma lipid and lipoprotein subfractions using Vertical Auto Profile-II methodology and directly measured insulin-mediated glucose disposal in 45 protease inhibitor (PI)-treated and non-PI-treated HIV-infected patients.RESULTS:PI-treated patients had higher total, LDL, and narrow-density LDL cholesterol (p <.05) and a trend toward higher triglycerides, whereas HDL cholesterol and LDL particle characteristics were unrelated to PI use or history of lipodystrophy. Insulin sensitivity did not differ on the basis of PI therapy, but decreased insulin sensitivity was associated with lower HDL and HDL-3 cholesterol (p <.01); elevated triglyceride (p <.01), VLDL 1+2, and VLDL 3a+3b lipoproteins (p <.01); and smaller, denser (more atherogenic) LDL particle characteristics (p <.01). Thus, the lipoprotein abnormality associated with PI use was increased LDL cholesterol, whereas changes in TG and HDL metabolism were associated with insulin resistance, independent of PI use.CONCLUSION:The variables of PI-treatment, dyslipidemia, lipodsytrophy, and insulin resistance do not always cluster together in HIV-infected patients, which suggests that the metabolic phenotype emerging in treated patients results from a complex interplay of drug effects, immune restoration, and baseline insulin sensitivity.

SEIDL, K., et al.: Noncontact Mapping of Ectopic Atrial Tachycardias: Different Characteristics of Isopotential Maps and Unipolar Electrogram. The success rate for catheter ablation of ectopic atrial tachycardia (AT) has been limited by the inherent difficulty in localizing the site of origin within the complex three‐dimensional structures of the atria. The objective of the study was to determine the usefulness of a noncontact mapping system for catheter ablation of AT. Radiofrequency ablation of 25 ATs was performed using a noncontact mapping system. Three different characteristics of isopotential maps and unipolar electrogram morphologies were observed: Group 1: Isopotential maps displayed a narrow, sharp ring of colors around a white, center spot. Unipolar electrograms revealed a Q‐S morphology with a rapid dV/dt. Group 2: Isopotential maps displayed a broad ring of colors with little or no white spot in the center. Unipolar electrograms revealed a low amplitude, broad and smooth Q‐S morphology in front of a second component with a rapid dV/dt. Group 3: Isopotential maps displayed a broad ring of colors. Unipolar electrogams revealed a low amplitude and fractionated waveform followed by endocardial breakthrough with a gradual dV/dt. Radiofrequency catheter ablation was successful in all ATs of groups 1 and 2, and failed in two of three ATs in group 3. The overall success rate was 92%. No severe complications were observed. Noncontact isopotential mapping is helpful to identify and characterize the origin of ectopic AT. Ablation success is associated with the characteristics of isopotential maps and unipolar electrogram morphologies. The overall success rate was 92%. (PACE 2003; 26[Pt. I]:16–25)

To describe the distribution of insulin sensitivity and glucose tolerance in HIV-infected patients, the authors measured insulin-mediated glucose disposal (IMGD) in 51 subjects (24 protease inhibitor (PI)-treated subjects and 27 non-PI-treated subjects). IMGD was determined by measuring the steady-state plasma glucose (SSPG) concentration during the last 30 minutes of a 180-minute intravenous infusion of octreotide, glucose, and insulin. In addition, oral glucose tolerance testing was performed. SSPG concentrations varied six-fold in both groups, and the mean values +/- SEM did not differ between PI-treated and non-PI-treated groups (8.7 +/- 0.9 vs. 8.0 +/- 0.7 mmol/L, respectively). The mean fasting plasma glucose concentration +/- SEM was higher in the PI-treated subjects than in the non-PI-treated subjects (5.44 +/- 0.11 vs. 5.05 +/- 0.11 mmol/L, respectively; p =.01), whereas fasting plasma insulin concentrations did not differ. PI-treated patients also had significantly higher plasma glucose (p =.001) and insulin (p =.03) responses to the oral glucose challenge. However, whereas the incremental plasma glucose response during the first 30 minutes was significantly higher in PI-treated patients, the incremental insulin response in the two groups was identical. In conclusion, insulin sensitivity varies widely in HIV-infected patients irrespective of PI treatment, and the adverse effect of PIs on insulin sensitivity is likely to be of modest magnitude. Finally, PI treatment may have an inhibitory effect on insulin secretion.

The success rate for catheter ablation of ectopic atrial tachycardia (AT) has been limited by the inherent difficulty in localizing the site of origin within the complex three-dimensional structures of the atria. The objective of the study was to determine the usefulness of a noncontact mapping system for catheter ablation of AT. Radiofrequency ablation of 25 ATs was performed using a noncontact mapping system. Three different characteristics of isopotential maps and unipolar electrogram morphologies were observed: Group 1: Isopotential maps displayed a narrow, sharp ring of colors around a white, center spot. Unipolar electrograms revealed a Q-S morphology with a rapid dV/dt. Group 2: Isopotential maps displayed a broad ring of colors with little or no white spot in the center. Unipolar electrograms revealed a low amplitude, broad and smooth Q-S morphology in front of a second component with a rapid dV/dt. Group 3: Isopotential maps displayed a broad ring of colors. Unipolar electrogams revealed a low amplitude and fractionated waveform followed by endocardial breakthrough with a gradual dV/dt. Radiofrequency catheter ablation was successful in all ATs of groups 1 and 2, and failed in two of three ATs in group 3. The overall success rate was 92%. No severe complications were observed. Noncontact isopotential mapping is helpful to identify and characterize the origin of ectopic AT. Ablation success is associated with the characteristics of isopotential maps and unipolar electrogram morphologies. The overall success rate was 92%.

The currently available technology for the diagnosis of arrhythmias is capable of diagnosing only stable, patient tolerated arrhythmias: single-beat electrophysiologic imaging of the heart's electrical activity is not possible with currently available technology. For some sort of arrythmias (e.g., non-sustained atrial tachycardia) a system capable to do so seems to be of high value

This article describes our experience with a staged “hybrid” approach to the treatment of drug resistant AF, in which the completeness of a single linear lesion in the RA was verified with a noncontact mapping system. Inferior vena cava‐tricuspid annulus ablation was performed and followed by the creation of a single intercaval lesion. The study population consisted of 24 patients with a 3.4 ± 1.6‐year history of drug resistant, severely symptomatic, lone paroxysmal (n = 19), or persistent (n = 5) AF. During a follow‐up of 8 ± 2.6 months, 12 (50%) patients remained asymptomatic and 6 (25%) had a significant decrease in AF episodes, while the arrhythmia was unchanged in 5 (21 %) patients and aggravated in 1 (4%) patient. Overall, a favorable clinical result was achieved in 18 (75%) patients.

BACKGROUND:Endocardial mapping of sustained arrhythmias has traditionally been performed with a roving diagnostic catheter. Although this approach is adequate for many tachyarrhythmias, it has limitations. The purpose of this study was to evaluate a novel noncontact mapping system for assessing atrial tachyarrhythmias.METHODS AND RESULTS:The mapping system consists of a 9F multielectrode-array balloon catheter that has 64 active electrodes and ring electrodes for emitting a locator signal. The locator signal was used to construct a 3-dimensional right atrial map; it was independently validated and was highly accurate. Virtual electrograms were calculated at 3360 endocardial sites in the right atrium. We evaluated right atrial activation by positioning the balloon catheter in the mid right atrium via a femoral venous approach. Experiments were performed on 12 normal mongrel dogs. The mean correlation coefficient between contact and virtual electrograms was 0.80+/-0.12 during sinus rhythm. Fifty episodes of atrial flutter induced in 11 animals were evaluated. In the majority of experiments, complete or almost complete reentrant circuits could be identified within the right atrium. Mean correlation coefficient between virtual and contact electrograms was 0.85+/-0.17 in atrial flutter. One hundred fifty-six episodes of pacing-induced atrial fibrillation were evaluated in 11 animals. Several distinct patterns of right atrial activation were seen, including single-activation wave fronts and multiple simultaneous-activation wave fronts. Mean correlation coefficient between virtual and contact electrograms during atrial fibrillation was 0.81+/-0.18. The accuracy of electrogram reconstruction was lower at sites >4.0 cm from the balloon center and at sites with a high spatial complexity of electrical activation.CONCLUSIONS:This novel noncontact mapping system can evaluate conduction patterns during sinus rhythm, demonstrate reentry during atrial flutter, and describe right atrial activation during atrial fibrillation. The accuracy of electrogram reconstruction was good at sites <4.0 cm from the balloon center, and thus the system has the ability to perform high-resolution multisite mapping of atrial tachyarrhythmias in vivo.

HomeCirculationVol. 95, No. 6Human Left Ventricular Endocardial Activation Mapping Using a Novel Noncontact Catheter Free AccessResearch ArticleDownload EPUBAboutView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessResearch ArticleDownload EPUBHuman Left Ventricular Endocardial Activation Mapping Using a Novel Noncontact Catheter Nicholas S. Peters, Warren M. Jackman, Richard J. Schilling, Graydon Beatty and D. Wyn Davies Nicholas S. PetersNicholas S. Peters , Warren M. JackmanWarren M. Jackman , Richard J. SchillingRichard J. Schilling , Graydon BeattyGraydon Beatty and D. Wyn DaviesD. Wyn Davies Originally published18 Mar 1997https://doi.org/10.1161/01.CIR.95.6.1658Circulation. 1997;95:1658–1660The patient was a 39-year-old male who had recurrent sustained monomorphic ventricular tachycardia, satisfying the electrocardiographic criteria for fascicular tachycardia, in a structurally normal heart.These isopotential maps were acquired from the patient's left ventricle during an otherwise routine electrophysiology study by deploying a catheter-mounted multielectrode array consisting of a wire braid on the surface of an 8-mL balloon (Endocardial Solutions Inc). Without endocardial contact, this system uses inverse solution mathematics (boundary-element method) to reconstruct 3360 "virtual" electrograms onto a shell model of the endocardium. A manually selected line of virtual electrograms shows a normal sequence of high-frequency potentials consistent with fascicular activation during sinus rhythm, which correlates with the activation process shown by isopotential mapping (Fig 1). During a brief, nonsustained episode of the patient's clinical tachycardia (Fig 2) the sequence of these presumed fascicular potentials is clearly altered in a manner consistent with the diagnosis of fascicular tachycardia and corresponding to an altered activation sequence on isopotential mapping. Despite its short duration, the tachycardia could be characterized in a single beat.This case illustrates the use of a novel catheter-based technology in acquiring extensive simultaneous data to create unique maps of endocardial activation during electrophysiological study of a conscious patient.From the Department of Cardiology (N.S.P., R.J.S., D.W.D.), St Mary's Hospital and Imperial College School of Medicine, London, UK; Department of Medicine (W.M.J.), University of Oklahoma Health Sciences Center, Oklahoma City, Okla; and Endocardial Solutions, Inc (G.B.), Saint Paul, Minn.The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke's Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke's Episcopal Hospital and Texas Heart Institute, 6720 Bertner, MC 4-265, Houston, TX 77030.Download figureDownload PowerPoint Figure 1. Sinus rhythm: A sequence of isopotential maps of the left ventricular endocardium (purple) modeled to the patient's chamber dimensions and opened along its anteroseptal margin. The location of the multielectrode array is represented by the yellow ellipsoid. Surface ECG lead I and selected virtual electrograms from a line following fascicular activation (I-P on the map) are shown beneath each map. The timing of each map is indicated by the white cursor, which progresses through the presystolic fascicular potentials (A and B). Fascicular activation propagates toward the apex, where it initiates ventricular activation (C).Download figureDownload PowerPoint Figure 2. Fascicular tachycardia: During tachycardia, the fascicular activation sequence is altered, starting near the left ventricular apex (A) and propagating toward the His bundle (B). This rapid retrograde fascicular activation is closely followed by ventricular activation (C). The relative delay in right ventricular activation produces a QRS complex with right bundle-branch block pattern in ECG lead I.This work was supported by the British Heart Foundation.FootnotesCorrespondence to Dr Nicholas S. Peters, Department of Cardiology, St Mary's Hospital, Praed St, London W2 1NY, UK. E-mail [email protected] Previous Back to top Next FiguresReferencesRelatedDetailsCited By LEMERY R (2012) Interventional Electrophysiology at the Crossroads: Cardiac Mapping, Ablation and Pacing Without Fluoroscopy, Journal of Cardiovascular Electrophysiology, 10.1111/j.1540-8167.2012.02373.x, 23:10, (1087-1091), Online publication date: 1-Oct-2012. 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FENICI R, PESOLA K, KORHONEN P, MAKIJARVI M, NENONEN J, TOIVONEN L, FENICI P and KATILA T (1998) Magnetocardiographic Pacemapping for Nonfluoroscopic Localization of Intracardiac Electrophysiology Catheters, Pacing and Clinical Electrophysiology, 10.1111/j.1540-8159.1998.tb01207.x, 21:11, (2492-2499), Online publication date: 1-Nov-1998. March 18, 1997Vol 95, Issue 6 Advertisement Article InformationMetrics Copyright © 1997 by American Heart Associationhttps://doi.org/10.1161/01.CIR.95.6.1658 Originally publishedMarch 18, 1997 Advertisement

Salomon, D.; Cirulli, V.; Hayek, A.; Beatty, G.; Crisa, L.; Torbett, B.; Gaber, O.; Fraga, D.; Ingram, R.; Glass, J.; Pierschbacher, M. Author Information