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John M. Morgan - One of the best experts on this subject based on the ideXlab platform.

  • Global Endocardial Electrical Restitution in Human Right and Left Ventricles Determined by Noncontact Mapping
    Journal of the American College of Cardiology, 2005
    Co-Authors: Arthur M. Yue, Paul R. Roberts, Michael R Franz, John M. Morgan
    Abstract:

    This study was aimed at evaluating global characteristics of electrical restitution in the human ventricle using Noncontact Mapping. Steep action potential restitution (slope >1) and conduction velocity (CV) restitution have been linked with propensity to ventricular fibrillation, but clinical measurement of global electrical restitution had not been feasible. Activation-recovery interval (ARI) and CV restitution curves were simultaneously constructed from 16 regional segments of the left and right ventricles in 8 patients (6 male, 2 female, age 42 +/- 17 years) following successful ablation of idiopathic ventricular tachycardia in the absence of structural disease guided by the Ensite 3000 system (Endocardial Solutions Inc., St. Paul, Minnesota). The ARIs were determined from reconstructed unipolar electrograms as validated with monophasic action potential recordings. The ARI restitution slopes were determined using the overlapping least-squares linear segments. Global electrical restitution curves were heterogeneous in shape and distribution. ARI restitution slope was >1 at 25% of 128 sites. The overall mean slope was 0.79 and was greater in the left than the right ventricle (0.93 +/- 0.49 vs. 0.65 +/- 0.26, p < 0.001). Dispersion of ARI restitution slopes increased with decreasing diastolic intervals. The CV restitution operated over a narrower range of diastolic intervals compared with ARI restitution, reaching a plateau (10 +/- 6 ms vs. 38 +/- 13 ms, p < 0.001) after refractoriness. The magnitude of CV restitution was also greater (steeper) than ARI restitution (25 +/- 10% vs. 18 +/- 9%, p < 0.001). Noncontact Mapping can be used to examine global electrical restitution in the human ventricle. The ARI restitution is heterogeneous, with a slope >1 at 25% of all sites. The heterogeneity of ARI and CV restitution may be important in determining myocardial electrical stability.

  • global endocardial electrical restitution in human right and left ventricles determined by Noncontact Mapping
    Journal of the American College of Cardiology, 2005
    Co-Authors: Arthur M. Yue, Paul R. Roberts, Michael R Franz, John M. Morgan
    Abstract:

    Objectives This study was aimed at evaluating global characteristics of electrical restitution in the human ventricle using Noncontact Mapping. Background Steep action potential restitution (slope >1) and conduction velocity (CV) restitution have been linked with propensity to ventricular fibrillation, but clinical measurement of global electrical restitution had not been feasible. Methods Activation-recovery interval (ARI) and CV restitution curves were simultaneously constructed from 16 regional segments of the left and right ventricles in 8 patients (6 male, 2 female, age 42 ± 17 years) following successful ablation of idiopathic ventricular tachycardia in the absence of structural disease guided by the Ensite 3000 system (Endocardial Solutions Inc., St. Paul, Minnesota). The ARIs were determined from reconstructed unipolar electrograms as validated with monophasic action potential recordings. The ARI restitution slopes were determined using the overlapping least-squares linear segments. Results Global electrical restitution curves were heterogeneous in shape and distribution. ARI restitution slope was >1 at 25% of 128 sites. The overall mean slope was 0.79 and was greater in the left than the right ventricle (0.93 ± 0.49 vs. 0.65 ± 0.26, p Conclusions Noncontact Mapping can be used to examine global electrical restitution in the human ventricle. The ARI restitution is heterogeneous, with a slope >1 at 25% of all sites. The heterogeneity of ARI and CV restitution may be important in determining myocardial electrical stability.

  • determination of human ventricular repolarization by Noncontact Mapping validation with monophasic action potential recordings
    Circulation, 2004
    Co-Authors: Arthur M. Yue, Tim R. Betts, Paul R. Roberts, J R Paisey, Steve Robinson, John M. Morgan
    Abstract:

    Background— Noncontact Mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. Methods and Results— MAPs were recorded from a total of 355 beats at 46 sites in the left or right ventricle of 9 patients undergoing ablation of ventricular tachycardia guided by NCM (EnSite system). Measurements were made during sinus rhythm, constant right ventricular pacing, and ventricular extrastimuli during restitution-curve construction. The EnGuide locator signal was used to document MAP catheter locations on the endocardial geometry. UE-determined activation-recovery interval (ARI) measured at the maximum derivative of the T wave (Wyatt method) and the minimum derivative of the positive T wave (alternative method) was correlated with MAP measured at 90% repolarization (MAP90%...

  • Determination of human ventricular repolarization by Noncontact Mapping: validation with monophasic action potential recordings.
    Circulation, 2004
    Co-Authors: Arthur M. Yue, Tim R. Betts, Paul R. Roberts, J R Paisey, Steve Robinson, John M. Morgan
    Abstract:

    Noncontact Mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. MAPs were recorded from a total of 355 beats at 46 sites in the left or right ventricle of 9 patients undergoing ablation of ventricular tachycardia guided by NCM (EnSite system). Measurements were made during sinus rhythm, constant right ventricular pacing, and ventricular extrastimuli during restitution-curve construction. The EnGuide locator signal was used to document MAP catheter locations on the endocardial geometry. UE-determined activation-recovery interval (ARI) measured at the maximum derivative of the T wave (Wyatt method) and the minimum derivative of the positive T wave (alternative method) was correlated with MAP measured at 90% repolarization (MAP90%) at the same sites. ARI correlated with MAP90% during steady state by the Wyatt method (r=0.83, P<0.001) and the alternative method (r=0.94, P<0.001). Restitution curves constructed from MAP and UE data exhibited the same characteristics, with a mean correlation coefficient of 0.95 (range, 0.90 to 0.99, P<0.001). The error between ARI and MAP90% was greater over a shorter diastolic coupling interval but was not influenced by distance of the sampling site from the multielectrode array. NCM accurately determines steady-state and dynamic endocardial repolarization in humans. Global, high-density, NCM data could be used to characterize abnormalities of human ventricular repolarization.

  • Radiofrequency ablation of idiopathic ventricular fibrillation guided by Noncontact Mapping.
    Journal of cardiovascular electrophysiology, 2004
    Co-Authors: Tim R. Betts, Arthur M. Yue, Paul R. Roberts, John M. Morgan
    Abstract:

    A 32-year-old man with idiopathic ventricular fibrillation and an implantable cardioverter defibrillator presented during a ventricular fibrillation storm. Frequent monomorphic ventricular ectopics with left bundle branch block morphology were documented, some of which initiated fibrillation. He underwent Noncontact Mapping of the right ventricle, during which the ventricular ectopics were mapped to a site in the free wall displaying a diastolic potential 80 ms before ectopic QRS onset. Following three radiofrequency energy applications, the ectopics were abolished. After 11-month follow-up, he has experienced no further arrhythmias. Noncontact Mapping may identify ablatable triggers of ventricular fibrillation and lead to successful outcomes even when only single ectopics are present.

Thomas Paul - One of the best experts on this subject based on the ideXlab platform.

  • catheter ablation of idiopathic left and right ventricular tachycardias in the pediatric population using Noncontact Mapping
    Heart Rhythm, 2010
    Co-Authors: Heike E Schneider, Thomas Kriebel, Klaus Jung, Verena Gravenhorst, Thomas Paul
    Abstract:

    Background Idiopathic ventricular tachycardia (VT) in children with a structurally normal heart can cause significant morbidity, and although rare, mortality. Conventional activation and pace Mapping may be limited by nonsustained tachycardia or unstable hemodynamics. Objective The aim of this study was to assess feasibility of catheter ablation of idiopathic VT in the pediatric population guided by Noncontact Mapping. Methods Twenty consecutive pediatric patients with idiopathic VT underwent electrophysiologic study with the intention to use the Noncontact Mapping system EnSite 3000 (EnSite Array, St. Jude Medical Inc., Minneapolis, Minnesota). The multielectrode balloon array was introduced into the left or right ventricle, respectively, and tachycardia was analyzed using color-coded isopotential maps as well as reconstructed unipolar electrograms on the virtual geometry. The region of origin was identified in all of them, and the site of earliest activation with a QS pattern of the unipolar electrograms was guided for sites of ablation. Results Idiopathic VT originated from the right ventricular outflow tract in 6 patients, from the left ventricle in 8, and from the aortic sinus cusp in 6 in this cohort with a median age of 14.4 (range: 4.8 to 20.9) years. Ablation was attempted in 18 of 20 children, and was acutely successful in 17 of these 18 (94%). During a mean follow-up of 2.3 ± 1.7 years, VT recurred in 3, 2 of them have been treated with a second procedure, resulting in an overall intermediate-term success in 16 of 18 (89%) children with idiopathic VT. Conclusion Noncontact Mapping can safely and effectively be used to map and guide catheter ablation of the tachycardia substrate of idiopathic VT in pediatric patients.

  • Catheter ablation of idiopathic left and right ventricular tachycardias in the pediatric population using Noncontact Mapping.
    Heart rhythm, 2010
    Co-Authors: Heike E Schneider, Thomas Kriebel, Klaus Jung, Verena Gravenhorst, Thomas Paul
    Abstract:

    Idiopathic ventricular tachycardia (VT) in children with a structurally normal heart can cause significant morbidity, and although rare, mortality. Conventional activation and pace Mapping may be limited by nonsustained tachycardia or unstable hemodynamics. The aim of this study was to assess feasibility of catheter ablation of idiopathic VT in the pediatric population guided by Noncontact Mapping. Twenty consecutive pediatric patients with idiopathic VT underwent electrophysiologic study with the intention to use the Noncontact Mapping system EnSite 3000 (EnSite Array, St. Jude Medical Inc., Minneapolis, Minnesota). The multielectrode balloon array was introduced into the left or right ventricle, respectively, and tachycardia was analyzed using color-coded isopotential maps as well as reconstructed unipolar electrograms on the virtual geometry. The region of origin was identified in all of them, and the site of earliest activation with a QS pattern of the unipolar electrograms was guided for sites of ablation. Idiopathic VT originated from the right ventricular outflow tract in 6 patients, from the left ventricle in 8, and from the aortic sinus cusp in 6 in this cohort with a median age of 14.4 (range: 4.8 to 20.9) years. Ablation was attempted in 18 of 20 children, and was acutely successful in 17 of these 18 (94%). During a mean follow-up of 2.3 +/- 1.7 years, VT recurred in 3, 2 of them have been treated with a second procedure, resulting in an overall intermediate-term success in 16 of 18 (89%) children with idiopathic VT. Noncontact Mapping can safely and effectively be used to map and guide catheter ablation of the tachycardia substrate of idiopathic VT in pediatric patients. Copyright (c) 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  • Noncontact Mapping and radiofrequency catheter ablation of fast and hemodynamically unstable ventricular tachycardia after surgical repair of tetralogy of fallot
    Journal of the American College of Cardiology, 2007
    Co-Authors: Thomas Kriebel, Heike E Schneider, Matthias Sigler, Philip J Saul, Thomas Paul
    Abstract:

    Objectives The goal of this work was to assess efficacy of radiofrequency (RF) ablation of fast ventricular tachycardia (VT) in patients after surgical repair of tetralogy of Fallot (TOF) guided by Noncontact Mapping. Background Ventricular tachycardias after repair of TOF are associated with significant morbidity and mortality. Methods Ten patients after surgical repair of TOF underwent electrophysiological study for hemodynamically unstable VT using the Noncontact Mapping system. Dynamic substrate Mapping was performed and activation was recorded during basic rhythm and induced VT (mean cycle length 269 ms) using color-coded isopotential maps and reconstructed unipolar electrograms. Results A total of 13 VTs were induced in the 10 patients. In 11 of 13 VTs, a macro–re-entrant mechanism was identified; 2 had a focal origin. For macro–re-entrant VT, RF current lesion lines were created between areas of residual conduction; in 2 patients, no RF current was delivered due to high risk of atrioventricular block. Focal applications were performed for the focal VTs. Ventricular tachycardia was not inducible after RF application in the 8 patients in whom ablation was attempted (100%, 80% of all patients). An internal cardioverter-defibrillator had already been implanted in 2 patients and was recommended to the rest of the group. During follow-up (mean 35.4 months), 6 of 8 patients with a successful procedure were still free of VT, and 2 patients had recurrence of VT with a different cycle length. Conclusions In patients with fast and unstable VT after surgical repair of TOF, Noncontact Mapping helped to identify the tachycardia substrate and allowed for effective and safe treatment by RF ablation.

  • Noncontact Mapping and radiofrequency catheter ablation of fast and hemodynamically unstable ventricular tachycardia after surgical repair of tetralogy of Fallot.
    Journal of the American College of Cardiology, 2007
    Co-Authors: Thomas Kriebel, Heike E Schneider, J. Philip Saul, Matthias Sigler, Thomas Paul
    Abstract:

    The goal of this work was to assess efficacy of radiofrequency (RF) ablation of fast ventricular tachycardia (VT) in patients after surgical repair of tetralogy of Fallot (TOF) guided by Noncontact Mapping. Ventricular tachycardias after repair of TOF are associated with significant morbidity and mortality. Ten patients after surgical repair of TOF underwent electrophysiological study for hemodynamically unstable VT using the Noncontact Mapping system. Dynamic substrate Mapping was performed and activation was recorded during basic rhythm and induced VT (mean cycle length 269 ms) using color-coded isopotential maps and reconstructed unipolar electrograms. A total of 13 VTs were induced in the 10 patients. In 11 of 13 VTs, a macro-re-entrant mechanism was identified; 2 had a focal origin. For macro-re-entrant VT, RF current lesion lines were created between areas of residual conduction; in 2 patients, no RF current was delivered due to high risk of atrioventricular block. Focal applications were performed for the focal VTs. Ventricular tachycardia was not inducible after RF application in the 8 patients in whom ablation was attempted (100%, 80% of all patients). An internal cardioverter-defibrillator had already been implanted in 2 patients and was recommended to the rest of the group. During follow-up (mean 35.4 months), 6 of 8 patients with a successful procedure were still free of VT, and 2 patients had recurrence of VT with a different cycle length. In patients with fast and unstable VT after surgical repair of TOF, Noncontact Mapping helped to identify the tachycardia substrate and allowed for effective and safe treatment by RF ablation.

  • Origin of electrical activation within the right atrial and left ventricular walls: differentiation by electrogram characteristics using the Noncontact Mapping system.
    Pacing and clinical electrophysiology : PACE, 2003
    Co-Authors: Maja Kroll, Thomas Kriebel, Britta Windhagen-mahnert, Birgit Franzbach, Christian Jux, Martina Zutz, Jürgen Tebbenjohanns, Thomas Paul
    Abstract:

    Clinical data using the Noncontact Mapping system (Ensite 3000) suggest that characteristics of the reconstructed unipolar electrograms may predict the origin of electrical activation within the atrial and ventricular walls (endocardial vs myocardial vs epicardial origin). Experimental data are lacking. In ten open-chest pigs (mean body weight 62 kg) cardiac pacing was performed at a cycle length of 600 ms with a pulse width of 2 ms and twice diastolic threshold from the endo-, the myo-, and the epicardium, respectively. Pacing was undertaken at three right atrial and three left ventricular sites, and cardiac activation was recorded with the Ensite system. Reconstructed unipolar electrograms at the location of earliest endocardial activation assessed by color coded isopotential maps were analyzed systematically for differences in morphology. The positive predictive value of atrial electrograms exhibiting an initial R wave during pacing for a subendocardial origin (i.e., myocardial or epicardial) was 0.96. The negative predictive value was 0.48. Electrograms generated during myocardial pacing exhibited increased maximal negative voltage and maximal dV/dt (−3 ± 1.8 mV, −798 ± 860 mV/ms, respectively) than the electrograms obtained during endocardial (−2 ± 1 mV, −377 ± 251 mV/ms, respectively) and epicardial pacing (−2.1 ± 0.7 mV, −440 ± 401 mV/ms, respectively, P < 0.01 for both parameters). During pacing at the left ventricular wall, occurrence of an initial R wave did not differ significantly between electrograms reconstructed during endocardial and subendocardial pacing. All other characteristics of the unipolar ventricular electrograms analyzed, except latency, did not differ significantly when compared to stimulation depth. Morphological characteristics of unipolar electrograms generated by the Noncontact Mapping system during pacing of the atrium allowed for discrimination of an endocardial versus a subendocardial origin of activation. At the ventricular level, characteristics of unipolar electrograms did not predict the origin of cardiac activation in this experimental setting. (PACE 2003; 26:1970–1978)

Thomas Kriebel - One of the best experts on this subject based on the ideXlab platform.

  • catheter ablation of idiopathic left and right ventricular tachycardias in the pediatric population using Noncontact Mapping
    Heart Rhythm, 2010
    Co-Authors: Heike E Schneider, Thomas Kriebel, Klaus Jung, Verena Gravenhorst, Thomas Paul
    Abstract:

    Background Idiopathic ventricular tachycardia (VT) in children with a structurally normal heart can cause significant morbidity, and although rare, mortality. Conventional activation and pace Mapping may be limited by nonsustained tachycardia or unstable hemodynamics. Objective The aim of this study was to assess feasibility of catheter ablation of idiopathic VT in the pediatric population guided by Noncontact Mapping. Methods Twenty consecutive pediatric patients with idiopathic VT underwent electrophysiologic study with the intention to use the Noncontact Mapping system EnSite 3000 (EnSite Array, St. Jude Medical Inc., Minneapolis, Minnesota). The multielectrode balloon array was introduced into the left or right ventricle, respectively, and tachycardia was analyzed using color-coded isopotential maps as well as reconstructed unipolar electrograms on the virtual geometry. The region of origin was identified in all of them, and the site of earliest activation with a QS pattern of the unipolar electrograms was guided for sites of ablation. Results Idiopathic VT originated from the right ventricular outflow tract in 6 patients, from the left ventricle in 8, and from the aortic sinus cusp in 6 in this cohort with a median age of 14.4 (range: 4.8 to 20.9) years. Ablation was attempted in 18 of 20 children, and was acutely successful in 17 of these 18 (94%). During a mean follow-up of 2.3 ± 1.7 years, VT recurred in 3, 2 of them have been treated with a second procedure, resulting in an overall intermediate-term success in 16 of 18 (89%) children with idiopathic VT. Conclusion Noncontact Mapping can safely and effectively be used to map and guide catheter ablation of the tachycardia substrate of idiopathic VT in pediatric patients.

  • Catheter ablation of idiopathic left and right ventricular tachycardias in the pediatric population using Noncontact Mapping.
    Heart rhythm, 2010
    Co-Authors: Heike E Schneider, Thomas Kriebel, Klaus Jung, Verena Gravenhorst, Thomas Paul
    Abstract:

    Idiopathic ventricular tachycardia (VT) in children with a structurally normal heart can cause significant morbidity, and although rare, mortality. Conventional activation and pace Mapping may be limited by nonsustained tachycardia or unstable hemodynamics. The aim of this study was to assess feasibility of catheter ablation of idiopathic VT in the pediatric population guided by Noncontact Mapping. Twenty consecutive pediatric patients with idiopathic VT underwent electrophysiologic study with the intention to use the Noncontact Mapping system EnSite 3000 (EnSite Array, St. Jude Medical Inc., Minneapolis, Minnesota). The multielectrode balloon array was introduced into the left or right ventricle, respectively, and tachycardia was analyzed using color-coded isopotential maps as well as reconstructed unipolar electrograms on the virtual geometry. The region of origin was identified in all of them, and the site of earliest activation with a QS pattern of the unipolar electrograms was guided for sites of ablation. Idiopathic VT originated from the right ventricular outflow tract in 6 patients, from the left ventricle in 8, and from the aortic sinus cusp in 6 in this cohort with a median age of 14.4 (range: 4.8 to 20.9) years. Ablation was attempted in 18 of 20 children, and was acutely successful in 17 of these 18 (94%). During a mean follow-up of 2.3 +/- 1.7 years, VT recurred in 3, 2 of them have been treated with a second procedure, resulting in an overall intermediate-term success in 16 of 18 (89%) children with idiopathic VT. Noncontact Mapping can safely and effectively be used to map and guide catheter ablation of the tachycardia substrate of idiopathic VT in pediatric patients. Copyright (c) 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  • Noncontact Mapping and radiofrequency catheter ablation of fast and hemodynamically unstable ventricular tachycardia after surgical repair of tetralogy of fallot
    Journal of the American College of Cardiology, 2007
    Co-Authors: Thomas Kriebel, Heike E Schneider, Matthias Sigler, Philip J Saul, Thomas Paul
    Abstract:

    Objectives The goal of this work was to assess efficacy of radiofrequency (RF) ablation of fast ventricular tachycardia (VT) in patients after surgical repair of tetralogy of Fallot (TOF) guided by Noncontact Mapping. Background Ventricular tachycardias after repair of TOF are associated with significant morbidity and mortality. Methods Ten patients after surgical repair of TOF underwent electrophysiological study for hemodynamically unstable VT using the Noncontact Mapping system. Dynamic substrate Mapping was performed and activation was recorded during basic rhythm and induced VT (mean cycle length 269 ms) using color-coded isopotential maps and reconstructed unipolar electrograms. Results A total of 13 VTs were induced in the 10 patients. In 11 of 13 VTs, a macro–re-entrant mechanism was identified; 2 had a focal origin. For macro–re-entrant VT, RF current lesion lines were created between areas of residual conduction; in 2 patients, no RF current was delivered due to high risk of atrioventricular block. Focal applications were performed for the focal VTs. Ventricular tachycardia was not inducible after RF application in the 8 patients in whom ablation was attempted (100%, 80% of all patients). An internal cardioverter-defibrillator had already been implanted in 2 patients and was recommended to the rest of the group. During follow-up (mean 35.4 months), 6 of 8 patients with a successful procedure were still free of VT, and 2 patients had recurrence of VT with a different cycle length. Conclusions In patients with fast and unstable VT after surgical repair of TOF, Noncontact Mapping helped to identify the tachycardia substrate and allowed for effective and safe treatment by RF ablation.

  • Noncontact Mapping and radiofrequency catheter ablation of fast and hemodynamically unstable ventricular tachycardia after surgical repair of tetralogy of Fallot.
    Journal of the American College of Cardiology, 2007
    Co-Authors: Thomas Kriebel, Heike E Schneider, J. Philip Saul, Matthias Sigler, Thomas Paul
    Abstract:

    The goal of this work was to assess efficacy of radiofrequency (RF) ablation of fast ventricular tachycardia (VT) in patients after surgical repair of tetralogy of Fallot (TOF) guided by Noncontact Mapping. Ventricular tachycardias after repair of TOF are associated with significant morbidity and mortality. Ten patients after surgical repair of TOF underwent electrophysiological study for hemodynamically unstable VT using the Noncontact Mapping system. Dynamic substrate Mapping was performed and activation was recorded during basic rhythm and induced VT (mean cycle length 269 ms) using color-coded isopotential maps and reconstructed unipolar electrograms. A total of 13 VTs were induced in the 10 patients. In 11 of 13 VTs, a macro-re-entrant mechanism was identified; 2 had a focal origin. For macro-re-entrant VT, RF current lesion lines were created between areas of residual conduction; in 2 patients, no RF current was delivered due to high risk of atrioventricular block. Focal applications were performed for the focal VTs. Ventricular tachycardia was not inducible after RF application in the 8 patients in whom ablation was attempted (100%, 80% of all patients). An internal cardioverter-defibrillator had already been implanted in 2 patients and was recommended to the rest of the group. During follow-up (mean 35.4 months), 6 of 8 patients with a successful procedure were still free of VT, and 2 patients had recurrence of VT with a different cycle length. In patients with fast and unstable VT after surgical repair of TOF, Noncontact Mapping helped to identify the tachycardia substrate and allowed for effective and safe treatment by RF ablation.

  • Origin of electrical activation within the right atrial and left ventricular walls: differentiation by electrogram characteristics using the Noncontact Mapping system.
    Pacing and clinical electrophysiology : PACE, 2003
    Co-Authors: Maja Kroll, Thomas Kriebel, Britta Windhagen-mahnert, Birgit Franzbach, Christian Jux, Martina Zutz, Jürgen Tebbenjohanns, Thomas Paul
    Abstract:

    Clinical data using the Noncontact Mapping system (Ensite 3000) suggest that characteristics of the reconstructed unipolar electrograms may predict the origin of electrical activation within the atrial and ventricular walls (endocardial vs myocardial vs epicardial origin). Experimental data are lacking. In ten open-chest pigs (mean body weight 62 kg) cardiac pacing was performed at a cycle length of 600 ms with a pulse width of 2 ms and twice diastolic threshold from the endo-, the myo-, and the epicardium, respectively. Pacing was undertaken at three right atrial and three left ventricular sites, and cardiac activation was recorded with the Ensite system. Reconstructed unipolar electrograms at the location of earliest endocardial activation assessed by color coded isopotential maps were analyzed systematically for differences in morphology. The positive predictive value of atrial electrograms exhibiting an initial R wave during pacing for a subendocardial origin (i.e., myocardial or epicardial) was 0.96. The negative predictive value was 0.48. Electrograms generated during myocardial pacing exhibited increased maximal negative voltage and maximal dV/dt (−3 ± 1.8 mV, −798 ± 860 mV/ms, respectively) than the electrograms obtained during endocardial (−2 ± 1 mV, −377 ± 251 mV/ms, respectively) and epicardial pacing (−2.1 ± 0.7 mV, −440 ± 401 mV/ms, respectively, P < 0.01 for both parameters). During pacing at the left ventricular wall, occurrence of an initial R wave did not differ significantly between electrograms reconstructed during endocardial and subendocardial pacing. All other characteristics of the unipolar ventricular electrograms analyzed, except latency, did not differ significantly when compared to stimulation depth. Morphological characteristics of unipolar electrograms generated by the Noncontact Mapping system during pacing of the atrium allowed for discrimination of an endocardial versus a subendocardial origin of activation. At the ventricular level, characteristics of unipolar electrograms did not predict the origin of cardiac activation in this experimental setting. (PACE 2003; 26:1970–1978)

Nicholas S. Peters - One of the best experts on this subject based on the ideXlab platform.

  • Multiple distinct right atrial endocardial origins in a patient with atrial tachycardia: Mapping and ablation using Noncontact Mapping.
    Pacing and clinical electrophysiology : PACE, 2004
    Co-Authors: Oliver R. Segal, Vias Markides, Prapa Kanagaratnam, Tom Wong, Nicholas S. Peters
    Abstract:

    Noncontact Mapping identified the endocardial origins of four distinct atrial tachycardias in a young patient with drug refractory palpitations and effected successful ablation with no recurrence of symptoms in 5 months of follow-up.

  • Localization of the Isthmus in Reentrant Circuits by Analysis of Electrograms Derived from Clinical Noncontact Mapping During Sinus Rhythm and Ventricular Tachycardia
    Journal of cardiovascular electrophysiology, 2004
    Co-Authors: Edward J. Ciaccio, D. Wyn Davies, Anthony W. Chow, Andrew L. Wit, Nicholas S. Peters
    Abstract:

    New methods for electrogram analysis accurately estimated reentrant circuit isthmus location and shape in a canine model. It was hypothesized that these methods also would locate reentrant circuits causing clinical ventricular tachycardia (VT). Intracardiac electrogram recordings, obtained with a Noncontact Mapping system, were analyzed retrospectively from 14 patients with reentrant VT who had undergone successful radiofrequency ablation for prevention of VT initiation. Unipolar electrograms from 256 uniformly distributed endocardial sites were reconstructed by mathematical transformation. Twenty-seven tachycardias were mapped; 15 (in 11 patients) had a complete endocardial reentrant circuit with a figure-of-eight conduction pattern. During sinus rhythm, the location and axis of the slowest and most uniform conduction in the region of latest endocardial activation (the primary axis), the limits of which were defined as boundaries with >15 ms difference in electrogram duration between contiguous recordings, identified the location and shape of the reentrant circuit isthmus with a mean sensitivity compared with activation Mapping of 79.3% and a mean specificity of 97.6%. The midpoint of a theoretical "estimated best ablation line" drawn perpendicular to the primary axis of activation, spanning the estimated isthmus location was within 1.3 +/- 0.2 cm (mean distance +/- SD) of the actual ablation site that terminated tachycardia. Analysis of VT electrograms, based on time shifts in the far-field component of the local electrogram when cycle length changed (piecewise linear adaptive template matching [PLATM] method) in 5 of the cases, accurately estimated the time interval between activation at the recording site and the circuit isthmus slow conduction zone where the effective ablation lesion had been placed, which is proportional to the distance between the two locations (mean difference compared with activation Mapping: +/-37.3 ms). In selected patients with VT who have a complete endocardial circuit, isthmus location and shape can be discerned by analysis of sinus rhythm or tachycardia electrograms, and an effective ablation site can be predicted without the need to construct activation maps of reentrant circuits.

  • localization of the isthmus in reentrant circuits by analysis of electrograms derived from clinical Noncontact Mapping during sinus rhythm and ventricular tachycardia
    Journal of Cardiovascular Electrophysiology, 2004
    Co-Authors: Edward J. Ciaccio, Andrew L. Wit, W Anthony M D Chow, Wyn D Davies, Nicholas S. Peters
    Abstract:

    Introduction: New methods for electrogram analysis accurately estimated reentrant circuit isthmus location and shape in a canine model. It was hypothesized that these methods also would locate reentrant circuits causing clinical ventricular tachycardia (VT). Methods and Results: Intracardiac electrogram recordings, obtained with a Noncontact Mapping system, were analyzed retrospectively from 14 patients with reentrant VT who had undergone successful radiofrequency ablation for prevention of VT initiation. Unipolar electrograms from 256 uniformly distributed endocardial sites were reconstructed by mathematical transformation. Twenty-seven tachycardias were mapped; 15 (in 11 patients) had a complete endocardial reentrant circuit with a figure-of-eight conduction pattern. During sinus rhythm, the location and axis of the slowest and most uniform conduction in the region of latest endocardial activation (the primary axis), the limits of which were defined as boundaries with >15 ms difference in electrogram duration between contiguous recordings, identified the location and shape of the reentrant circuit isthmus with a mean sensitivity compared with activation Mapping of 79.3% and a mean specificity of 97.6%. The midpoint of a theoretical “estimated best ablation line” drawn perpendicular to the primary axis of activation, spanning the estimated isthmus location was within 1.3 ± 0.2 cm (mean distance ± SD) of the actual ablation site that terminated tachycardia. Analysis of VT electrograms, based on time shifts in the far-field component of the local electrogram when cycle length changed (piecewise linear adaptive template matching [PLATM] method) in 5 of the cases, accurately estimated the time interval between activation at the recording site and the circuit isthmus slow conduction zone where the effective ablation lesion had been placed, which is proportional to the distance between the two locations (mean difference compared with activation Mapping: ±37.3 ms). Conclusion: In selected patients with VT who have a complete endocardial circuit, isthmus location and shape can be discerned by analysis of sinus rhythm or tachycardia electrograms, and an effective ablation site can be predicted without the need to construct activation maps of reentrant circuits. (J Cardiovasc Electrophysiol, Vol. 15, pp. 27-36, January 2004)

  • Characterization of the anatomy and conduction velocities of the human right atrial flutter circuit determined by Noncontact Mapping.
    Journal of the American College of Cardiology, 2001
    Co-Authors: Richard J. Schilling, Nicholas S. Peters, Jeffrey J. Goldberger, Alan H. Kadish, D. Wyn Davies
    Abstract:

    Abstract OBJECTIVES This study was done to characterize human right atrial (RA) flutter (AFL) using Noncontact Mapping. BACKGROUND Atrial flutter has been mapped using sequential techniques, but complex anatomy makes simultaneous global RA Mapping difficult. METHODS Noncontact Mapping was used to map the RA of 13 patients with AFL (5 with previous attempts), 11 with counterclockwise and 2 with clockwise AFL. “Reconstructed” electrograms were validated against contact electrograms using cross-correlation. The Cartesian coordinates of points on a virtual endocardium were used to calculate the length and thus the conduction velocity (CV) of the AFL wave front within the tricuspid annulus-inferior vena cave isthmus (IS) and either side of the crista terminalis (CT). RESULTS When clearly seen, the AFL wave front split (n = 3) or turned in the region of the coronary sinus os (n = 6). Activation progressed toward the tricuspid annulus (TA) from the surrounding RA in 10 patients, suggesting that the leading edge of the reentry wave front is not always at the TA. The IS length and CV was 47.73 ± 24.40 mm (mean ± SD) and 0.74 ± 0.36 m/s. The CV was similar for the smooth and trabeculated RA (1.16 ± 0.48 m/s and 1.22 ± 0.65 m/s, respectively [p = 0.67]) and faster than the IS (p = 0.03 and p = 0.05 for smooth and trabeculated, respectively). CONCLUSIONS Noncontact Mapping of AFL has been validated and has demonstrated that IS CV is significantly slower than either side of the CT.

  • Catheter ablation of ventricular tachycardia related to coronary artery disease: The role of Noncontact Mapping
    Current Cardiology Reports, 2000
    Co-Authors: Anthony W. C. Chow, Richard J. Schilling, Nicholas S. Peters, D. Wyn Davies
    Abstract:

    There are a number of limitations associated with conventional Mapping for ablation of ventricular tachycardia (VT) in ischemic heart disease, such as the high recurrence rates after initially successful ablation. The development of a Noncontact Mapping system capable of producing high-resolution isopotential maps of the entire left ventricle has enabled rapid identification of diastolic activity that maintains VT for ablation. With this system it is possible to map nonsustained and fast unstable as well as stable VTs. In this article we review the historic background and concepts of Noncontact Mapping, its clinical application, and the results of ablations for human VT guided by this Mapping system.

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  • determination of human ventricular repolarization by Noncontact Mapping validation with monophasic action potential recordings
    Circulation, 2004
    Co-Authors: Arthur M. Yue, Tim R. Betts, Paul R. Roberts, J R Paisey, Steve Robinson, John M. Morgan
    Abstract:

    Background— Noncontact Mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. Methods and Results— MAPs were recorded from a total of 355 beats at 46 sites in the left or right ventricle of 9 patients undergoing ablation of ventricular tachycardia guided by NCM (EnSite system). Measurements were made during sinus rhythm, constant right ventricular pacing, and ventricular extrastimuli during restitution-curve construction. The EnGuide locator signal was used to document MAP catheter locations on the endocardial geometry. UE-determined activation-recovery interval (ARI) measured at the maximum derivative of the T wave (Wyatt method) and the minimum derivative of the positive T wave (alternative method) was correlated with MAP measured at 90% repolarization (MAP90%...

  • Determination of human ventricular repolarization by Noncontact Mapping: validation with monophasic action potential recordings.
    Circulation, 2004
    Co-Authors: Arthur M. Yue, Tim R. Betts, Paul R. Roberts, J R Paisey, Steve Robinson, John M. Morgan
    Abstract:

    Noncontact Mapping (NCM) has not been validated as a clinical technique to measure ventricular repolarization. We used NCM to determine repolarization characteristics by analysis of reconstructed unipolar electrograms (UEs) at the same sites as monophasic action potential (MAP) recordings in the human ventricle. MAPs were recorded from a total of 355 beats at 46 sites in the left or right ventricle of 9 patients undergoing ablation of ventricular tachycardia guided by NCM (EnSite system). Measurements were made during sinus rhythm, constant right ventricular pacing, and ventricular extrastimuli during restitution-curve construction. The EnGuide locator signal was used to document MAP catheter locations on the endocardial geometry. UE-determined activation-recovery interval (ARI) measured at the maximum derivative of the T wave (Wyatt method) and the minimum derivative of the positive T wave (alternative method) was correlated with MAP measured at 90% repolarization (MAP90%) at the same sites. ARI correlated with MAP90% during steady state by the Wyatt method (r=0.83, P<0.001) and the alternative method (r=0.94, P<0.001). Restitution curves constructed from MAP and UE data exhibited the same characteristics, with a mean correlation coefficient of 0.95 (range, 0.90 to 0.99, P<0.001). The error between ARI and MAP90% was greater over a shorter diastolic coupling interval but was not influenced by distance of the sampling site from the multielectrode array. NCM accurately determines steady-state and dynamic endocardial repolarization in humans. Global, high-density, NCM data could be used to characterize abnormalities of human ventricular repolarization.

  • Radiofrequency ablation of idiopathic ventricular fibrillation guided by Noncontact Mapping.
    Journal of cardiovascular electrophysiology, 2004
    Co-Authors: Tim R. Betts, Arthur M. Yue, Paul R. Roberts, John M. Morgan
    Abstract:

    A 32-year-old man with idiopathic ventricular fibrillation and an implantable cardioverter defibrillator presented during a ventricular fibrillation storm. Frequent monomorphic ventricular ectopics with left bundle branch block morphology were documented, some of which initiated fibrillation. He underwent Noncontact Mapping of the right ventricle, during which the ventricular ectopics were mapped to a site in the free wall displaying a diastolic potential 80 ms before ectopic QRS onset. Following three radiofrequency energy applications, the ectopics were abolished. After 11-month follow-up, he has experienced no further arrhythmias. Noncontact Mapping may identify ablatable triggers of ventricular fibrillation and lead to successful outcomes even when only single ectopics are present.

  • radiofrequency ablation of idiopathic left ventricular tachycardia at the site of earliest activation as determined by Noncontact Mapping
    Journal of Cardiovascular Electrophysiology, 2000
    Co-Authors: Tim R. Betts, Paul R. Roberts, Stuart A. Aelen, John M. Morgan
    Abstract:

    Ablation of Idiopathic LV Tachycardia. Introduction. The most effective method for guiding radiofrequency (RF) ablation of idiopathic left ventricular tachycardia (ILVT) has yet to be determined. We investigated the use of Noncontact Mapping in five patients with this condition. Methods and Results. The multielectrode array was positioned in the left ventricular apex via the retrograde approach. Isopotential color maps of ILVT were examined to determine the site of earliest endocardial activation. The ablation catheter was steered to the target site using the locator signal. Pace Mapping was performed and contact electrograms examined for diastolic potentials. RF energy was applied to the target site. Sustained ventricular tachycardia was induced in 2 patients and nonsustained ventricular tachycardia in 3. The site of earliest activation was at the apical Septum in 3. the inferior apex in I, and the base of the inferior wall in 1. Mean timing was 21 ± 10) msec before onset of the surface QRS. Diastolic activity was visualized with Noncontact Mapping at the base of the septum in 1 patient. A Purkinje potential was seen at the ablation site in only 1 patient. No diastolic activity was seen in the remaining 3 patients. Tachycardia was successfully terminated in all 5 patients with a median of four RF applications. No patient suffered a recurrence after 9.6 ± 4.7 months of follow-up. Conclusion. By identifying the precise site of earliest activation during ILVT, Noncontact Mapping has been shown to be an effective and safe method for guiding RF ablation. (J Cardiovasc Electrophysiol Vol. 11. pp 1094-1101. October 2000)

  • electrophysiological Mapping and ablation of intra atrial reentry tachycardia after fontan surgery with the use of a Noncontact Mapping system
    Circulation, 2000
    Co-Authors: Tim R. Betts, Paul R. Roberts, Stuart Allen, Anthony P Salmon, Barry R Keeton, Marcus P Haw, John M. Morgan
    Abstract:

    Background—Atrial tachyarrhythmias are a complication of Fontan surgery. Conventional electrophysiological Mapping and ablation techniques are limited by the complex anatomic and surgical substrate and a high arrhythmia recurrence rate. This study investigates the use of Noncontact Mapping to identify arrhythmia circuits and guide ablation in Fontan patients. Methods and Results—Eleven arrhythmias were recorded in 6 patients. Noncontact Mapping improved recognition of the anatomic and surgical substrate and identified exit sites from zones of slow conduction in all clinical arrhythmias. Radiofrequency linear lesions were targeted across these critical zones in 5 patients. One patient underwent surgical cryotherapy. Although immediate success was achieved in 3 of 5 patients with radiofrequency ablation, 2 patients had a recurrence after a mean of 6.4 months of follow-up. The patient who underwent cryoablation remains free of arrhythmias. Conclusions—Noncontact Mapping can identify arrhythmia circuits in th...