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William G Stevenson - One of the best experts on this subject based on the ideXlab platform.
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ventricular mapping during atrial and right ventricular pacing relation of electrogram parameters to ventricular tachycardia Reentry circuits after myocardial infarction
Journal of Interventional Cardiac Electrophysiology, 2004Co-Authors: Corinna Brunckhorst, Etienne Delacretaz, Kyoko Soejima, Warren M Jackman, Hiroshi Nakagawa, Karlheinz Kuck, Shlomo Benhaim, Burkhardt Seifert, William G StevensonAbstract:Introduction: Ventricular tachycardia (VT) late after myocardial infarction is usually due to Reentry in the border zone of the infarct area. Identification of critical parts of the VT Reentry circuit by catheter mapping without needing to induce VT is a desirable goal for VT ablation. The aim of this study was to develop a model to predict Reentry circuit locations based on characteristics of sinus or paced electrograms and pace mapping (PM) recorded from the infarct region.
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characteristics of electrograms recorded at Reentry circuit sites and bystanders during ventricular tachycardia after myocardial infarction
Journal of the American College of Cardiology, 1999Co-Authors: Dusan Z Kocovic, Peter L Friedman, Tomoo Harada, William G StevensonAbstract:Abstract OBJECTIVES The purpose of this study was to determine the relation of isolated potentials (IPs) recorded during ventricular tachycardia (VT) to Reentry circuit sites identified by entrainment. BACKGROUND Reentry circuits causing VT late after myocardial infarction are complex. Both IPs and entrainment have been useful for identifying successful ablation sites, but the relation of IPs to the location in the Reentry circuit as determined by entrainment has not been completely defined. METHODS Data from catheter mapping of 70 monomorphic VTs in 36 patients with prior myocardial infarction were retrospectively analyzed. Entrainment followed by radiofrequency current (RF) ablation was performed at 384 sites. On the basis of entrainment, sites were classified as Reentry circuit exit, central–proximal, inner or outer loop sites. Sites outside the circuit were divided into remote and adjacent bystanders. RESULTS Isolated potentials were recorded at 50% (51 of 101) of Reentry circuit exit, central and proximal sites as compared with only 8% (11 of 146, p CONCLUSIONS Isolated potentials are a useful guide to sites in the central–proximal region of the Reentry circuit, but often fail to identify exit sites where ablation is successful. Entrainment and analysis of electrograms provide complementary information during mapping of VT.
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exploring postinfarction reentrant ventricular tachycardia with entrainment mapping
Journal of the American College of Cardiology, 1997Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Isaac Wiener, Peter L Friedman, Dusan Z Kocovic, Tomoo Harada, Hafiza KhanAbstract:Ventricular tachycardia late after myocardial infarction is usually due to Reentry in the infarct region. These Reentry circuits can be large, complex and difficult to define, impeding study in the electrophysiology laboratory and making catheter ablation difficult. Pacing through the electrodes of the mapping catheter provides a new approach to mapping. When pacing stimuli capture the effects on the tachycardia depend on the location of the pacing site relative to the Reentry circuit. The effects observed allow identification of various portions of the Reentry circuit, without the need for locating the entire circuit. Isthmuses where relatively small lesions produced by radiofrequency catheter ablation can interrupt Reentry can often be identified. A classification that divides Reentry circuits into one or more functional components helps to conceptualize the Reentry circuit and predicts the likelihood that heating with radiofrequency current will terminate tachycardia. These methods are helping to define human Reentry circuits.
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relation of pace mapping qrs configuration and conduction delay to ventricular tachycardia Reentry circuits in human infarct scars
Journal of the American College of Cardiology, 1995Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:Abstract Objectives . This study sought to determine the relation of the paced QRS configuration and conduction delay during pace mapping to Reentry circuit sites in patients with ventricular tachycardia late after myocardial infarction. Background . The QRS configuration produced by ventricular pacing during sinus rhythm (pace mapping) can locate focal idiopathic ventricular tachycardias during catheter mapping, but postinfarction Reentry circuits may be relatively large and contain regions of slow conduction. We hypothesized that for postinfarction ventricular tachycardia, 1) pacing during sinus rhythm at Reentry circuit sites distant from the exit from the scar would produce a QRS configuration different from the tachycardia; and 2) a stimulus to QRS delay during pace mapping may be a useful guide to Reentry circuit slow conduction zones. Methods . Catheter mapping and ablation were performed in 18 consecutive patients with ventricular tachycardia after myocardial infarction. At 85 endocardial sites in 13 patients, 12-lead electrocardiograms (ECGs) were recorded during pace mapping, and participation of each site in a Reentry circuit was then evaluated by entrainment techniques during induced ventricular tachycardia or by application of radiofrequency current. Results . Pace maps resembled tachycardia at 40 ms was observed at ≥70% of Reentry circuit sites. Conclusions . At many sites in postinfarction ventricular Reentry circuits, the QRS configuration during pace mapping does not resemble the ventricular tachycardia QRS complex, consistent with relatively large Reentry circuits or regions of functional conduction block during ventricular tachycardia. A stimulus to QRS delay during pace mapping is consistent with slow conduction and may aid in targeting endocardial sites for further evaluation during tachycardia.
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activation times in and adjacent to Reentry circuits during entrainment implications for mapping ventricular tachycardia
American Heart Journal, 1994Co-Authors: Hafiza H Khan, William G StevensonAbstract:Abstract Myocardial infarct scars giving rise to reentrant ventricular tachycardia can contain “bystander” areas of abnormal electrical activity that are difficult to distinguish from Reentry circuit sites. Pacing to entrain ventricular tachycardia with analysis of electrograms at the pacing site is useful to identify Reentry circuit sites but assumes that electrograms reflect activation times at the recording site. The purpose of this study was to determine whether a similar analysis could be applied to electrograms recorded from sites distant from the pacing site. In computer simulations, activation times at sites in and adjacent to figure-eight Reentry circuits were analyzed during entrainment of tachycardia by pacing at various sites. During entrainment, activation at Reentry circuit sites activated by the stimulated orthodromic wavefronts maintains the same relation to the QRS complex as that during tachycardia. The return cycle from the last entrained electrogram to the following electrogram equals the tachycardia cycle length. The same findings occur, however, at bystander sites activated by stimulated wavefronts that have propagated orthodromically through the circuit. When a Reentry circuit site is activated by stimulated antidromic wavefronts, the electrogram to QRS interval is shorter than that during tachycardia, the return cycle may be less than the tachycardia cycle length, and the site may appear to be dissociated from the tachycardia, despite its location in the circuit. If the entrained electrogram to QRS interval exceeds the tachycardia electrogram to QRS interval and the return cycle length exceeds the tachycardia cycle length, it is likely that both pacing and recording sites are outside the Reentry circuit. Thus, during entrainment, failure to dissociate an electrogram from the QRS complex and the return cycle length does not reliably indicate the relation of the recording site to the Reentry circuit when the recording and pacing sites are separate.
Isaac Wiener - One of the best experts on this subject based on the ideXlab platform.
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exploring postinfarction reentrant ventricular tachycardia with entrainment mapping
Journal of the American College of Cardiology, 1997Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Isaac Wiener, Peter L Friedman, Dusan Z Kocovic, Tomoo Harada, Hafiza KhanAbstract:Ventricular tachycardia late after myocardial infarction is usually due to Reentry in the infarct region. These Reentry circuits can be large, complex and difficult to define, impeding study in the electrophysiology laboratory and making catheter ablation difficult. Pacing through the electrodes of the mapping catheter provides a new approach to mapping. When pacing stimuli capture the effects on the tachycardia depend on the location of the pacing site relative to the Reentry circuit. The effects observed allow identification of various portions of the Reentry circuit, without the need for locating the entire circuit. Isthmuses where relatively small lesions produced by radiofrequency catheter ablation can interrupt Reentry can often be identified. A classification that divides Reentry circuits into one or more functional components helps to conceptualize the Reentry circuit and predicts the likelihood that heating with radiofrequency current will terminate tachycardia. These methods are helping to define human Reentry circuits.
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relation of pace mapping qrs configuration and conduction delay to ventricular tachycardia Reentry circuits in human infarct scars
Journal of the American College of Cardiology, 1995Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:Abstract Objectives . This study sought to determine the relation of the paced QRS configuration and conduction delay during pace mapping to Reentry circuit sites in patients with ventricular tachycardia late after myocardial infarction. Background . The QRS configuration produced by ventricular pacing during sinus rhythm (pace mapping) can locate focal idiopathic ventricular tachycardias during catheter mapping, but postinfarction Reentry circuits may be relatively large and contain regions of slow conduction. We hypothesized that for postinfarction ventricular tachycardia, 1) pacing during sinus rhythm at Reentry circuit sites distant from the exit from the scar would produce a QRS configuration different from the tachycardia; and 2) a stimulus to QRS delay during pace mapping may be a useful guide to Reentry circuit slow conduction zones. Methods . Catheter mapping and ablation were performed in 18 consecutive patients with ventricular tachycardia after myocardial infarction. At 85 endocardial sites in 13 patients, 12-lead electrocardiograms (ECGs) were recorded during pace mapping, and participation of each site in a Reentry circuit was then evaluated by entrainment techniques during induced ventricular tachycardia or by application of radiofrequency current. Results . Pace maps resembled tachycardia at 40 ms was observed at ≥70% of Reentry circuit sites. Conclusions . At many sites in postinfarction ventricular Reentry circuits, the QRS configuration during pace mapping does not resemble the ventricular tachycardia QRS complex, consistent with relatively large Reentry circuits or regions of functional conduction block during ventricular tachycardia. A stimulus to QRS delay during pace mapping is consistent with slow conduction and may aid in targeting endocardial sites for further evaluation during tachycardia.
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identification of Reentry circuit sites during catheter mapping and radiofrequency ablation of ventricular tachycardia late after myocardial infarction
Circulation, 1993Co-Authors: William G Stevenson, Leslie A Saxon, H Khan, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:BACKGROUNDVentricular tachycardia Reentry circuits in chronic infarct scars can contain slow conduction zones, which are difficult to distinguish from bystander areas adjacent to the circuit during catheter mapping. This study developed criteria for identifying Reentry circuit sites using computer simulations. These criteria then were tested during catheter mapping in humans to predict sites at which radiofrequency current application terminated ventricular tachycardia.METHODS AND RESULTSIn computer simulations, effects of single stimuli and stimulus trains at sites in and adjacent to Reentry circuits were analyzed. Entrainment with concealed fusion, defined as ventricular tachycardia entrainment with no change in QRS morphology, could occur during stimulation in Reentry circuit common pathways and adjacent bystander sites. Pacing at Reentry circuit common pathway sites, the stimulus to QRS (S-QRS) interval equals the electrogram to QRS interval (EG-QRS) during tachycardia. The postpacing interval from th...
Philip T Sager - One of the best experts on this subject based on the ideXlab platform.
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exploring postinfarction reentrant ventricular tachycardia with entrainment mapping
Journal of the American College of Cardiology, 1997Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Isaac Wiener, Peter L Friedman, Dusan Z Kocovic, Tomoo Harada, Hafiza KhanAbstract:Ventricular tachycardia late after myocardial infarction is usually due to Reentry in the infarct region. These Reentry circuits can be large, complex and difficult to define, impeding study in the electrophysiology laboratory and making catheter ablation difficult. Pacing through the electrodes of the mapping catheter provides a new approach to mapping. When pacing stimuli capture the effects on the tachycardia depend on the location of the pacing site relative to the Reentry circuit. The effects observed allow identification of various portions of the Reentry circuit, without the need for locating the entire circuit. Isthmuses where relatively small lesions produced by radiofrequency catheter ablation can interrupt Reentry can often be identified. A classification that divides Reentry circuits into one or more functional components helps to conceptualize the Reentry circuit and predicts the likelihood that heating with radiofrequency current will terminate tachycardia. These methods are helping to define human Reentry circuits.
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relation of pace mapping qrs configuration and conduction delay to ventricular tachycardia Reentry circuits in human infarct scars
Journal of the American College of Cardiology, 1995Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:Abstract Objectives . This study sought to determine the relation of the paced QRS configuration and conduction delay during pace mapping to Reentry circuit sites in patients with ventricular tachycardia late after myocardial infarction. Background . The QRS configuration produced by ventricular pacing during sinus rhythm (pace mapping) can locate focal idiopathic ventricular tachycardias during catheter mapping, but postinfarction Reentry circuits may be relatively large and contain regions of slow conduction. We hypothesized that for postinfarction ventricular tachycardia, 1) pacing during sinus rhythm at Reentry circuit sites distant from the exit from the scar would produce a QRS configuration different from the tachycardia; and 2) a stimulus to QRS delay during pace mapping may be a useful guide to Reentry circuit slow conduction zones. Methods . Catheter mapping and ablation were performed in 18 consecutive patients with ventricular tachycardia after myocardial infarction. At 85 endocardial sites in 13 patients, 12-lead electrocardiograms (ECGs) were recorded during pace mapping, and participation of each site in a Reentry circuit was then evaluated by entrainment techniques during induced ventricular tachycardia or by application of radiofrequency current. Results . Pace maps resembled tachycardia at 40 ms was observed at ≥70% of Reentry circuit sites. Conclusions . At many sites in postinfarction ventricular Reentry circuits, the QRS configuration during pace mapping does not resemble the ventricular tachycardia QRS complex, consistent with relatively large Reentry circuits or regions of functional conduction block during ventricular tachycardia. A stimulus to QRS delay during pace mapping is consistent with slow conduction and may aid in targeting endocardial sites for further evaluation during tachycardia.
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identification of Reentry circuit sites during catheter mapping and radiofrequency ablation of ventricular tachycardia late after myocardial infarction
Circulation, 1993Co-Authors: William G Stevenson, Leslie A Saxon, H Khan, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:BACKGROUNDVentricular tachycardia Reentry circuits in chronic infarct scars can contain slow conduction zones, which are difficult to distinguish from bystander areas adjacent to the circuit during catheter mapping. This study developed criteria for identifying Reentry circuit sites using computer simulations. These criteria then were tested during catheter mapping in humans to predict sites at which radiofrequency current application terminated ventricular tachycardia.METHODS AND RESULTSIn computer simulations, effects of single stimuli and stimulus trains at sites in and adjacent to Reentry circuits were analyzed. Entrainment with concealed fusion, defined as ventricular tachycardia entrainment with no change in QRS morphology, could occur during stimulation in Reentry circuit common pathways and adjacent bystander sites. Pacing at Reentry circuit common pathway sites, the stimulus to QRS (S-QRS) interval equals the electrogram to QRS interval (EG-QRS) during tachycardia. The postpacing interval from th...
Leslie A Saxon - One of the best experts on this subject based on the ideXlab platform.
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exploring postinfarction reentrant ventricular tachycardia with entrainment mapping
Journal of the American College of Cardiology, 1997Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Isaac Wiener, Peter L Friedman, Dusan Z Kocovic, Tomoo Harada, Hafiza KhanAbstract:Ventricular tachycardia late after myocardial infarction is usually due to Reentry in the infarct region. These Reentry circuits can be large, complex and difficult to define, impeding study in the electrophysiology laboratory and making catheter ablation difficult. Pacing through the electrodes of the mapping catheter provides a new approach to mapping. When pacing stimuli capture the effects on the tachycardia depend on the location of the pacing site relative to the Reentry circuit. The effects observed allow identification of various portions of the Reentry circuit, without the need for locating the entire circuit. Isthmuses where relatively small lesions produced by radiofrequency catheter ablation can interrupt Reentry can often be identified. A classification that divides Reentry circuits into one or more functional components helps to conceptualize the Reentry circuit and predicts the likelihood that heating with radiofrequency current will terminate tachycardia. These methods are helping to define human Reentry circuits.
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relation of pace mapping qrs configuration and conduction delay to ventricular tachycardia Reentry circuits in human infarct scars
Journal of the American College of Cardiology, 1995Co-Authors: William G Stevenson, Leslie A Saxon, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:Abstract Objectives . This study sought to determine the relation of the paced QRS configuration and conduction delay during pace mapping to Reentry circuit sites in patients with ventricular tachycardia late after myocardial infarction. Background . The QRS configuration produced by ventricular pacing during sinus rhythm (pace mapping) can locate focal idiopathic ventricular tachycardias during catheter mapping, but postinfarction Reentry circuits may be relatively large and contain regions of slow conduction. We hypothesized that for postinfarction ventricular tachycardia, 1) pacing during sinus rhythm at Reentry circuit sites distant from the exit from the scar would produce a QRS configuration different from the tachycardia; and 2) a stimulus to QRS delay during pace mapping may be a useful guide to Reentry circuit slow conduction zones. Methods . Catheter mapping and ablation were performed in 18 consecutive patients with ventricular tachycardia after myocardial infarction. At 85 endocardial sites in 13 patients, 12-lead electrocardiograms (ECGs) were recorded during pace mapping, and participation of each site in a Reentry circuit was then evaluated by entrainment techniques during induced ventricular tachycardia or by application of radiofrequency current. Results . Pace maps resembled tachycardia at 40 ms was observed at ≥70% of Reentry circuit sites. Conclusions . At many sites in postinfarction ventricular Reentry circuits, the QRS configuration during pace mapping does not resemble the ventricular tachycardia QRS complex, consistent with relatively large Reentry circuits or regions of functional conduction block during ventricular tachycardia. A stimulus to QRS delay during pace mapping is consistent with slow conduction and may aid in targeting endocardial sites for further evaluation during tachycardia.
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identification of Reentry circuit sites during catheter mapping and radiofrequency ablation of ventricular tachycardia late after myocardial infarction
Circulation, 1993Co-Authors: William G Stevenson, Leslie A Saxon, H Khan, Philip T Sager, Holly R Middlekauff, Paul D Natterson, Isaac WienerAbstract:BACKGROUNDVentricular tachycardia Reentry circuits in chronic infarct scars can contain slow conduction zones, which are difficult to distinguish from bystander areas adjacent to the circuit during catheter mapping. This study developed criteria for identifying Reentry circuit sites using computer simulations. These criteria then were tested during catheter mapping in humans to predict sites at which radiofrequency current application terminated ventricular tachycardia.METHODS AND RESULTSIn computer simulations, effects of single stimuli and stimulus trains at sites in and adjacent to Reentry circuits were analyzed. Entrainment with concealed fusion, defined as ventricular tachycardia entrainment with no change in QRS morphology, could occur during stimulation in Reentry circuit common pathways and adjacent bystander sites. Pacing at Reentry circuit common pathway sites, the stimulus to QRS (S-QRS) interval equals the electrogram to QRS interval (EG-QRS) during tachycardia. The postpacing interval from th...
Masood Akhtar - One of the best experts on this subject based on the ideXlab platform.
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bundle branch Reentry a mechanism of ventricular tachycardia in the absence of myocardial or valvular dysfunction
Journal of the American College of Cardiology, 1993Co-Authors: Zalmen Blanck, Mohammad Jazayeri, Anwer Dhala, Sanjay Deshpande, Masood AkhtarAbstract:Objective, The aim of this study was to present bundle branch recentry as the mechanism of sustained ventricular tachycardia in the absence of myocardial or valvular dysfunction. Background. Previous reports have documented the relation between structural heart disease and bundle branch reentrant ventricular tachycardia. Myocardial or valvular dysfunction has thus far been recognised as the only anatomic substrate for the development of this tachycardia. Methods. Three patients with a wide QRS complex tachycardia underwent noninvasive and invasive cardiac evaluation and electrophysiologic studies to identify the substrate and mechanism of tachycardia. Catheter ablation of the right bundle branch using radiofrequency current was performed in each patient. Results. The patients were ail men (aged 54, 34 and 72 years) who presented with presyncope, palpitation and cardiac arrest, respectively. Electrocardiography during sinus rhythm revealed nonspecific intraventricular conduction delay in all three patients. Cardiac evaluation revealed no evidence of myocardial or valvular dysfunction in any patient. The baseline HV interval was prolonged in each patient (90, 100 and 75 ms, respectively). Programmed right ventricular stimulation initiated bundle branch reentrant tachycardia with typical left (three patients) and right (one patient) bundle branch block pattern. Catheter ablation of the right bundle branch using radiofrequency current abolished bundle branch Reentry in all three patients. After 26-, 13- and 8-month follow-up periods, complete right bundle branch block persisted, and all three patients remained asymptomatic without antiarrhythmic drugs. Conclusions. Sustained bundle branch Reentry can be a clinical arrhythmia in patients with no identifiable myocardial or valvular dysfunction except for isolated conduction abnormalities in the His-Purkinje system. This mechanism of tachycardia should be recognized during electrophysiologic evaluation, given the seriousness of this arrhythmia and the availability of effective treatment.
