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Hungfat Tse - One of the best experts on this subject based on the ideXlab platform.
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treatment of Atrial fibrillation with an implantable Atrial Defibrillator long term results
European Heart Journal, 2003Co-Authors: Christoph J Geller, Hungfat Tse, Chupak Lau, Carl Timmermans, John A Camm, Werner Jung, Christian Wolpert, Sven Reek, Torsten Kayser, Hein J J WellensAbstract:Objectives To evaluate the long-term outcome with an implantable Atrial Defibrillator (IAD) in patients with recurrent Atrial fibrillation (AF). Background Maintenance of sinus rhythm using repeated internal cardioversion shocks has been shown to be effective and safe in short-term studies but long term follow-up is unknown. Methods Since 1995, 136 patients (30 women) with symptomatic, drug-refractory Atrial fibrillation were implanted with an IAD (METRIX, InControl). This analysis was performed after a median of 40 (range 7–66) months after implantation. Results In 26 patients, the programmed mode was not documented during last follow-up, four patients had died. Of the remaining 106 patients (mean age 58±10, range 34 – 79 years), 39 were actively delivering therapy with the device, in 14 patients the device was used to monitor the arrhythmia but no shocks were delivered, and in 53 patients it was turned off or explanted. Increases in defibrillation thresholds ( n =7), patient intolerance of multiple cardioversion shocks ( n =15), and significant bradycardia requiring dual-chamber pacing ( n =12) were the main reasons for discontinuation of therapy in addition to battery depletion ( n =19). After explantation, efforts to maintain sinus rhythm were continued in 17 patients whereas rate control was attempted in 36 patients. Conclusions A strategy of maintaining sinus rhythm long-term with an IAD is feasible in a proportion of patients. However, patient selection is critical, and technical improvements (i.e. higher shock energies, dual-chamber pacing and additional preventive and anti-tachycardia pacing algorithms) are required to increase the number of patients having long term benefit, and frequent arrhythmia recurrences and patient intolerance to repeated cardioversion shocks remain a major limitation.
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reversible impairment of left and right ventricular systolic and diastolic function during short lasting Atrial fibrillation in patients with an implantable Atrial Defibrillator a tissue doppler imaging study
Pacing and Clinical Electrophysiology, 2001Co-Authors: Qiong Wang, Hungfat Tse, Chupak Lau, Sumkin Leung, Kathy Laifan Lee, Vella Tsang, Gregory M AyersAbstract:YU, C.-M., et al.: Reversible Impairment of Left and Right Ventricular Systolic and Diastolic Function During Short-Lasting Atrial Fibrillation in Patients with an Implantable Atrial Defibrillator: A Tissue Doppler Imaging Study. AF with a fast ventricular response may cause ventricular mechanical impairment, though whether short-lasting AF with satisfactory rate control may affect ventricular function is unknown. This study investigated if prompt cardioversion by an implantable Atrial Defibrillator (IAD) may prevent left (LV) and right ventricular (RV) systolic and diastolic dysfunction. Ten patients (mean age 61 ± 9 years, 8 men) with paroxysmal AF without structural heart disease who received an IAD were studied by echocardiography and tissue Doppler imaging (TDI) for both ventricles. Measurements were made during baseline sinus rhythm and at 1-minute, 20-minute, 4-hour, and 1-week postcardioversion of an episode of spontaneous AF. The occurrence of AF and the ventricular rate were monitored at 2-hour intervals by the device. There were 50 episodes of AF with a mean duration of 8.8 ± 8.9 days (2 hours to 37 days). There was no difference in M-mode measured LV fractional shortening and ejection fraction between baseline sinus rhythm and after cardioversion. However, the TDI derived myocardial systolic velocity (TDI-S) was significantly lower at 1- minute postcardioversion and was normalized at 1 week in both LVs (baseline: 5.7 ± 1.8, 1 minute: 4.2 ± 1.0, 20 minutes: 4.3 ± 0.9, 4 hours: 4.8 ± 1.0, 1 week: 5.5 ± 1.8 cm/s; P 48 hours) resulted in a more depressed TDI-S in LV (> 48 hours: 4.2 ± 1.0, ≤ 48 hours: 5.3 ± 1.3 cm/s; P < 0.01). Shocks in sinus rhythm did not affect any of the above echocardiographic parameters. Therefore, despite adequate rate control, short-lasting AF impairs systolic and diastolic function in both ventricles, which improves gradually after cardioversion. Early restoration of sinus rhythm by an IAD minimizes ventricular dysfunction. TDI is a sensitive tool to assess early systolic and diastolic dysfunction.
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effect of the implantable Atrial Defibrillator on the natural history of Atrial fibrillation
Journal of Cardiovascular Electrophysiology, 1999Co-Authors: Hungfat Tse, Chupak Lau, Kathy Laifun Lee, Gregory F Michaud, Bradley P Knight, Fred Morady, Adam S StrickbergerAbstract:Implantable Atrial Defibrillator. Introduction: The purpose of our study was to evaluate the effect of repeated cardioversion with an implantable Atrial Defibrillator on the clinical outcome of patients with Atrial fibrillation. Methods and Results: The effects of the implantable Atrial Defibrillator on the total duration of Atrial fibrillation, number of Atrial fibrillation recurrences, and left Atrial size were evaluated prospectively in 16 patients with Atrial fibrillation (13 men and 3 women; mean age 58 ± 11 years). Seven patients bad no cardiovascular disease, 5 patients had hypertension. 3 patients had coronary heart disease, and 1 patient bad congenital heart disease. Eight patients had paroxysmal Atrial fibrillation for a mean duration of 80 ± 61 months, and eight patients had persistent Atrial fibrillation for a mean duration of 68 ± 119 months. Except for one patient who received digoxin throughout the study, alt patients received the same Class I or III antiarrhythmic agent throughout the study. The implantable Atrial Defibrillator successfully converted 50 (93%) of 54 spontaneous episodes of Atrial fibrillation in 12 patients. During the initial 3 months of clinical follow-up, the Atrial Defibrillator documented 261 ± 270 hours of Atrial fibrillation compared with 126 ± 172 hours (P = 0.01) during the subsequent 3 months. The left Atrial size decreased from 4.4 ± 0.7 cm at the time of Atrial Defibrillator implantation to 4.1 ± 0.6 cm (P = 0.02) 6 months later. The number of Atrial fibrillation recurrences did not change. These findings were observed in the absence of changes in drug therapy. No complications were observed. Conclusion: Restoration and maintenance of sinus rhythm in patients with Atrial fibrillation by repeated cardioversion with an implantable Atrial Defibrillator was associated with a reduction in the total arrhythmia duration and a reduction in left Atrial size. These results suggest that maintenance of sinus rhythm with the Atrial Defibrillator may reverse the remodeling process associated with Atrial fibrillation.
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Atrial fibrillation detection and r wave synchronization by metrix implantable Atrial Defibrillator implications for long term efficacy and safety
Circulation, 1999Co-Authors: Hungfat Tse, C P Lau, J S Sra, Harry J G M Crijns, N Edvardsson, S Kacet, D G WyseAbstract:Background—The long-term efficacy of Atrial fibrillation (AF) detection and R-wave synchronization are critical safety requirements for the development of an implantable Atrial Defibrillator (IAD) for treatment of AF. Methods and Results—The long-term efficacy of the Metrix IAD for AF detection and R-wave synchronization was tested in 51 patients. The mean duration of follow-up was 259±138 days (72 to 613 days). AF detection tests were performed 2240 times during observed operation with 100% specificity and 92.3% sensitivity for differentiation between sinus rhythm and AF; 2219 episodes and their electrograms stored in the device during AF detection were analyzed. The positive predictive value of the AF detection algorithm was 97.4% (lower 95% confidence limit [CL], 94.5%) in the out-of-hospital setting. A total of 242 435 R waves were analyzed for R-wave synchronization. Of these, 49% were marked for synchronized shock delivery, 82% of sinus rhythm and 36% of AF R waves, respectively. All shock markers w...
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initial clinical experience with an implantable human Atrial Defibrillator
Pacing and Clinical Electrophysiology, 1997Co-Authors: Chupak Lau, Hungfat Tse, Kathy Laifun Lee, Ngaisang Lok, Mark Sopher, Francis Murgatroyd, John A CammAbstract:Low energy biAtrial shock is an effective means of restoring sinus rhythm in patients with Atrial fibrillation (AF). Ventricular proarrhythmia is avoided provided that shocks are well synchronized to R waves that are not at closely coupled intervals or preceded by long-short cycles. Based on these principles, an implantable Atrial Defibrillator has been developed and was implanted in three patients with drug refractory paroxysmal AF. The device detects AF via an actively fixed right Atrial and a self-retaining coronary sinus defibrillating leads, and delivers 3/3 ms biphasic shocks up to 300 V synchronized to the R wave. The mean implant threshold (ED50) was 195 V (1.8 J). and minimum voltage at conversion during follow-up assessments at 1, 3, and 6 months were 260 V, 2.5 J. 250 V, 2.3 J, and 300 V, 3.0 J respectively. Detection of AF was 100% specific and shocks were 100% synchronized, although only a proportion of synchronized R waves were considered suitable for shock delivery primarily because of closely coupled cycles. Three patients had 9 spontaneous AF episodes, 8/9 (89%) successfully defibrillated by shocks of 260-300 V. Sedation was not used in 4 out of 9 (45%) episodes. Backup ventricular pacing was initiated by the device in 6 out of (67%) episodes. One patient had more frequent AF after lead placement, which subsided after a change of medication. There was no ventricular proarrhythmia. It is concluded that an implantable Atrial Defibrillator is a viable therapy for selected patients with paroxysmal AF. The device is capable of accurate AF detection, R wave synchronization and ventricular support pacing after successful defibrillation of AF.
Hein J J Wellens - One of the best experts on this subject based on the ideXlab platform.
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treatment of Atrial fibrillation with an implantable Atrial Defibrillator long term results
European Heart Journal, 2003Co-Authors: Christoph J Geller, Hungfat Tse, Chupak Lau, Carl Timmermans, John A Camm, Werner Jung, Christian Wolpert, Sven Reek, Torsten Kayser, Hein J J WellensAbstract:Objectives To evaluate the long-term outcome with an implantable Atrial Defibrillator (IAD) in patients with recurrent Atrial fibrillation (AF). Background Maintenance of sinus rhythm using repeated internal cardioversion shocks has been shown to be effective and safe in short-term studies but long term follow-up is unknown. Methods Since 1995, 136 patients (30 women) with symptomatic, drug-refractory Atrial fibrillation were implanted with an IAD (METRIX, InControl). This analysis was performed after a median of 40 (range 7–66) months after implantation. Results In 26 patients, the programmed mode was not documented during last follow-up, four patients had died. Of the remaining 106 patients (mean age 58±10, range 34 – 79 years), 39 were actively delivering therapy with the device, in 14 patients the device was used to monitor the arrhythmia but no shocks were delivered, and in 53 patients it was turned off or explanted. Increases in defibrillation thresholds ( n =7), patient intolerance of multiple cardioversion shocks ( n =15), and significant bradycardia requiring dual-chamber pacing ( n =12) were the main reasons for discontinuation of therapy in addition to battery depletion ( n =19). After explantation, efforts to maintain sinus rhythm were continued in 17 patients whereas rate control was attempted in 36 patients. Conclusions A strategy of maintaining sinus rhythm long-term with an IAD is feasible in a proportion of patients. However, patient selection is critical, and technical improvements (i.e. higher shock energies, dual-chamber pacing and additional preventive and anti-tachycardia pacing algorithms) are required to increase the number of patients having long term benefit, and frequent arrhythmia recurrences and patient intolerance to repeated cardioversion shocks remain a major limitation.
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are electrophysiological changes induced by longer lasting Atrial fibrillation reversible observations using the Atrial Defibrillator
Circulation, 1999Co-Authors: Luzmaria Rodriguez, Carl Timmermans, Hein J J WellensAbstract:Background—Studies in animal hearts have shown shortening of the Atrial effective refractory period (AERP) and loss of the relation between the AERP and heart rate after prolonged periods of Atrial fibrillation (AF). The purposes of this study were (1) to evaluate Atrial electrophysiology after a long period of sinus rhythm in patients who had longer lasting recurrent AF that was successfully treated with the Metrix Atrioverter and (2) to analyze the effect of prompt cardioversion on subsequent AF episodes and the duration of sinus rhythm. Methods and Results—Four patients with recurrent AF (duration, 3 to 21 years; mean±SD, 13±7.6 years) were studied after the implantation of an Atrioverter. The Atrioverter stores and analyzes 3 minutes of cardiac rhythm every hour. Before implantation, AERP was measured. During a mean follow-up of 14 months, 52 spontaneous (39 treated and 18 nontreated) AF episodes occurred while the patients were on antiarrhythmic drugs. All patients were electrophysiologically studied...
Carl Timmermans - One of the best experts on this subject based on the ideXlab platform.
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treatment of Atrial fibrillation with an implantable Atrial Defibrillator long term results
European Heart Journal, 2003Co-Authors: Christoph J Geller, Hungfat Tse, Chupak Lau, Carl Timmermans, John A Camm, Werner Jung, Christian Wolpert, Sven Reek, Torsten Kayser, Hein J J WellensAbstract:Objectives To evaluate the long-term outcome with an implantable Atrial Defibrillator (IAD) in patients with recurrent Atrial fibrillation (AF). Background Maintenance of sinus rhythm using repeated internal cardioversion shocks has been shown to be effective and safe in short-term studies but long term follow-up is unknown. Methods Since 1995, 136 patients (30 women) with symptomatic, drug-refractory Atrial fibrillation were implanted with an IAD (METRIX, InControl). This analysis was performed after a median of 40 (range 7–66) months after implantation. Results In 26 patients, the programmed mode was not documented during last follow-up, four patients had died. Of the remaining 106 patients (mean age 58±10, range 34 – 79 years), 39 were actively delivering therapy with the device, in 14 patients the device was used to monitor the arrhythmia but no shocks were delivered, and in 53 patients it was turned off or explanted. Increases in defibrillation thresholds ( n =7), patient intolerance of multiple cardioversion shocks ( n =15), and significant bradycardia requiring dual-chamber pacing ( n =12) were the main reasons for discontinuation of therapy in addition to battery depletion ( n =19). After explantation, efforts to maintain sinus rhythm were continued in 17 patients whereas rate control was attempted in 36 patients. Conclusions A strategy of maintaining sinus rhythm long-term with an IAD is feasible in a proportion of patients. However, patient selection is critical, and technical improvements (i.e. higher shock energies, dual-chamber pacing and additional preventive and anti-tachycardia pacing algorithms) are required to increase the number of patients having long term benefit, and frequent arrhythmia recurrences and patient intolerance to repeated cardioversion shocks remain a major limitation.
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initial clinical experience with ambulatory use of an implantable Atrial Defibrillator for conversion of Atrial fibrillation
Circulation, 2000Co-Authors: Emile G Daoud, Carl Timmermans, Christopher L Fellows, Robert F Hoyt, Robert Lemery, Kathy Dawson, Gregory M AyersAbstract:Background—A recent study has shown that the implantable Atrial Defibrillator can restore sinus rhythm in patients with recurrent Atrial fibrillation when therapy was delivered under physician observation. The objective of this study was to evaluate the safety and efficacy of ambulatory use of the implantable Atrial Defibrillator. Methods and Results—An Atrial Defibrillator was implanted in 105 patients (75 men; mean age, 59±12 years) with recurrent, symptomatic, drug-refractory Atrial fibrillation. After successful 3-month testing, patients could transition to ambulatory delivery of shock therapy. Patients completed questionnaires regarding shock therapy discomfort and therapy satisfaction using a 10-point visual-analog scale (1 represented “not at all,” 10 represented “extremely”) after each treated episode of Atrial fibrillation. During a mean follow-up of 11.7 months, 48 of 105 patients satisfied criteria for transition and received therapy for 275 episodes of Atrial fibrillation. Overall shock therap...
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are electrophysiological changes induced by longer lasting Atrial fibrillation reversible observations using the Atrial Defibrillator
Circulation, 1999Co-Authors: Luzmaria Rodriguez, Carl Timmermans, Hein J J WellensAbstract:Background—Studies in animal hearts have shown shortening of the Atrial effective refractory period (AERP) and loss of the relation between the AERP and heart rate after prolonged periods of Atrial fibrillation (AF). The purposes of this study were (1) to evaluate Atrial electrophysiology after a long period of sinus rhythm in patients who had longer lasting recurrent AF that was successfully treated with the Metrix Atrioverter and (2) to analyze the effect of prompt cardioversion on subsequent AF episodes and the duration of sinus rhythm. Methods and Results—Four patients with recurrent AF (duration, 3 to 21 years; mean±SD, 13±7.6 years) were studied after the implantation of an Atrioverter. The Atrioverter stores and analyzes 3 minutes of cardiac rhythm every hour. Before implantation, AERP was measured. During a mean follow-up of 14 months, 52 spontaneous (39 treated and 18 nontreated) AF episodes occurred while the patients were on antiarrhythmic drugs. All patients were electrophysiologically studied...
Chupak Lau - One of the best experts on this subject based on the ideXlab platform.
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treatment of Atrial fibrillation with an implantable Atrial Defibrillator long term results
European Heart Journal, 2003Co-Authors: Christoph J Geller, Hungfat Tse, Chupak Lau, Carl Timmermans, John A Camm, Werner Jung, Christian Wolpert, Sven Reek, Torsten Kayser, Hein J J WellensAbstract:Objectives To evaluate the long-term outcome with an implantable Atrial Defibrillator (IAD) in patients with recurrent Atrial fibrillation (AF). Background Maintenance of sinus rhythm using repeated internal cardioversion shocks has been shown to be effective and safe in short-term studies but long term follow-up is unknown. Methods Since 1995, 136 patients (30 women) with symptomatic, drug-refractory Atrial fibrillation were implanted with an IAD (METRIX, InControl). This analysis was performed after a median of 40 (range 7–66) months after implantation. Results In 26 patients, the programmed mode was not documented during last follow-up, four patients had died. Of the remaining 106 patients (mean age 58±10, range 34 – 79 years), 39 were actively delivering therapy with the device, in 14 patients the device was used to monitor the arrhythmia but no shocks were delivered, and in 53 patients it was turned off or explanted. Increases in defibrillation thresholds ( n =7), patient intolerance of multiple cardioversion shocks ( n =15), and significant bradycardia requiring dual-chamber pacing ( n =12) were the main reasons for discontinuation of therapy in addition to battery depletion ( n =19). After explantation, efforts to maintain sinus rhythm were continued in 17 patients whereas rate control was attempted in 36 patients. Conclusions A strategy of maintaining sinus rhythm long-term with an IAD is feasible in a proportion of patients. However, patient selection is critical, and technical improvements (i.e. higher shock energies, dual-chamber pacing and additional preventive and anti-tachycardia pacing algorithms) are required to increase the number of patients having long term benefit, and frequent arrhythmia recurrences and patient intolerance to repeated cardioversion shocks remain a major limitation.
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reversible impairment of left and right ventricular systolic and diastolic function during short lasting Atrial fibrillation in patients with an implantable Atrial Defibrillator a tissue doppler imaging study
Pacing and Clinical Electrophysiology, 2001Co-Authors: Qiong Wang, Hungfat Tse, Chupak Lau, Sumkin Leung, Kathy Laifan Lee, Vella Tsang, Gregory M AyersAbstract:YU, C.-M., et al.: Reversible Impairment of Left and Right Ventricular Systolic and Diastolic Function During Short-Lasting Atrial Fibrillation in Patients with an Implantable Atrial Defibrillator: A Tissue Doppler Imaging Study. AF with a fast ventricular response may cause ventricular mechanical impairment, though whether short-lasting AF with satisfactory rate control may affect ventricular function is unknown. This study investigated if prompt cardioversion by an implantable Atrial Defibrillator (IAD) may prevent left (LV) and right ventricular (RV) systolic and diastolic dysfunction. Ten patients (mean age 61 ± 9 years, 8 men) with paroxysmal AF without structural heart disease who received an IAD were studied by echocardiography and tissue Doppler imaging (TDI) for both ventricles. Measurements were made during baseline sinus rhythm and at 1-minute, 20-minute, 4-hour, and 1-week postcardioversion of an episode of spontaneous AF. The occurrence of AF and the ventricular rate were monitored at 2-hour intervals by the device. There were 50 episodes of AF with a mean duration of 8.8 ± 8.9 days (2 hours to 37 days). There was no difference in M-mode measured LV fractional shortening and ejection fraction between baseline sinus rhythm and after cardioversion. However, the TDI derived myocardial systolic velocity (TDI-S) was significantly lower at 1- minute postcardioversion and was normalized at 1 week in both LVs (baseline: 5.7 ± 1.8, 1 minute: 4.2 ± 1.0, 20 minutes: 4.3 ± 0.9, 4 hours: 4.8 ± 1.0, 1 week: 5.5 ± 1.8 cm/s; P 48 hours) resulted in a more depressed TDI-S in LV (> 48 hours: 4.2 ± 1.0, ≤ 48 hours: 5.3 ± 1.3 cm/s; P < 0.01). Shocks in sinus rhythm did not affect any of the above echocardiographic parameters. Therefore, despite adequate rate control, short-lasting AF impairs systolic and diastolic function in both ventricles, which improves gradually after cardioversion. Early restoration of sinus rhythm by an IAD minimizes ventricular dysfunction. TDI is a sensitive tool to assess early systolic and diastolic dysfunction.
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effect of the implantable Atrial Defibrillator on the natural history of Atrial fibrillation
Journal of Cardiovascular Electrophysiology, 1999Co-Authors: Hungfat Tse, Chupak Lau, Kathy Laifun Lee, Gregory F Michaud, Bradley P Knight, Fred Morady, Adam S StrickbergerAbstract:Implantable Atrial Defibrillator. Introduction: The purpose of our study was to evaluate the effect of repeated cardioversion with an implantable Atrial Defibrillator on the clinical outcome of patients with Atrial fibrillation. Methods and Results: The effects of the implantable Atrial Defibrillator on the total duration of Atrial fibrillation, number of Atrial fibrillation recurrences, and left Atrial size were evaluated prospectively in 16 patients with Atrial fibrillation (13 men and 3 women; mean age 58 ± 11 years). Seven patients bad no cardiovascular disease, 5 patients had hypertension. 3 patients had coronary heart disease, and 1 patient bad congenital heart disease. Eight patients had paroxysmal Atrial fibrillation for a mean duration of 80 ± 61 months, and eight patients had persistent Atrial fibrillation for a mean duration of 68 ± 119 months. Except for one patient who received digoxin throughout the study, alt patients received the same Class I or III antiarrhythmic agent throughout the study. The implantable Atrial Defibrillator successfully converted 50 (93%) of 54 spontaneous episodes of Atrial fibrillation in 12 patients. During the initial 3 months of clinical follow-up, the Atrial Defibrillator documented 261 ± 270 hours of Atrial fibrillation compared with 126 ± 172 hours (P = 0.01) during the subsequent 3 months. The left Atrial size decreased from 4.4 ± 0.7 cm at the time of Atrial Defibrillator implantation to 4.1 ± 0.6 cm (P = 0.02) 6 months later. The number of Atrial fibrillation recurrences did not change. These findings were observed in the absence of changes in drug therapy. No complications were observed. Conclusion: Restoration and maintenance of sinus rhythm in patients with Atrial fibrillation by repeated cardioversion with an implantable Atrial Defibrillator was associated with a reduction in the total arrhythmia duration and a reduction in left Atrial size. These results suggest that maintenance of sinus rhythm with the Atrial Defibrillator may reverse the remodeling process associated with Atrial fibrillation.
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initial clinical experience with an implantable human Atrial Defibrillator
Pacing and Clinical Electrophysiology, 1997Co-Authors: Chupak Lau, Hungfat Tse, Kathy Laifun Lee, Ngaisang Lok, Mark Sopher, Francis Murgatroyd, John A CammAbstract:Low energy biAtrial shock is an effective means of restoring sinus rhythm in patients with Atrial fibrillation (AF). Ventricular proarrhythmia is avoided provided that shocks are well synchronized to R waves that are not at closely coupled intervals or preceded by long-short cycles. Based on these principles, an implantable Atrial Defibrillator has been developed and was implanted in three patients with drug refractory paroxysmal AF. The device detects AF via an actively fixed right Atrial and a self-retaining coronary sinus defibrillating leads, and delivers 3/3 ms biphasic shocks up to 300 V synchronized to the R wave. The mean implant threshold (ED50) was 195 V (1.8 J). and minimum voltage at conversion during follow-up assessments at 1, 3, and 6 months were 260 V, 2.5 J. 250 V, 2.3 J, and 300 V, 3.0 J respectively. Detection of AF was 100% specific and shocks were 100% synchronized, although only a proportion of synchronized R waves were considered suitable for shock delivery primarily because of closely coupled cycles. Three patients had 9 spontaneous AF episodes, 8/9 (89%) successfully defibrillated by shocks of 260-300 V. Sedation was not used in 4 out of 9 (45%) episodes. Backup ventricular pacing was initiated by the device in 6 out of (67%) episodes. One patient had more frequent AF after lead placement, which subsided after a change of medication. There was no ventricular proarrhythmia. It is concluded that an implantable Atrial Defibrillator is a viable therapy for selected patients with paroxysmal AF. The device is capable of accurate AF detection, R wave synchronization and ventricular support pacing after successful defibrillation of AF.
Werner Jung - One of the best experts on this subject based on the ideXlab platform.
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treatment of Atrial fibrillation with an implantable Atrial Defibrillator long term results
European Heart Journal, 2003Co-Authors: Christoph J Geller, Hungfat Tse, Chupak Lau, Carl Timmermans, John A Camm, Werner Jung, Christian Wolpert, Sven Reek, Torsten Kayser, Hein J J WellensAbstract:Objectives To evaluate the long-term outcome with an implantable Atrial Defibrillator (IAD) in patients with recurrent Atrial fibrillation (AF). Background Maintenance of sinus rhythm using repeated internal cardioversion shocks has been shown to be effective and safe in short-term studies but long term follow-up is unknown. Methods Since 1995, 136 patients (30 women) with symptomatic, drug-refractory Atrial fibrillation were implanted with an IAD (METRIX, InControl). This analysis was performed after a median of 40 (range 7–66) months after implantation. Results In 26 patients, the programmed mode was not documented during last follow-up, four patients had died. Of the remaining 106 patients (mean age 58±10, range 34 – 79 years), 39 were actively delivering therapy with the device, in 14 patients the device was used to monitor the arrhythmia but no shocks were delivered, and in 53 patients it was turned off or explanted. Increases in defibrillation thresholds ( n =7), patient intolerance of multiple cardioversion shocks ( n =15), and significant bradycardia requiring dual-chamber pacing ( n =12) were the main reasons for discontinuation of therapy in addition to battery depletion ( n =19). After explantation, efforts to maintain sinus rhythm were continued in 17 patients whereas rate control was attempted in 36 patients. Conclusions A strategy of maintaining sinus rhythm long-term with an IAD is feasible in a proportion of patients. However, patient selection is critical, and technical improvements (i.e. higher shock energies, dual-chamber pacing and additional preventive and anti-tachycardia pacing algorithms) are required to increase the number of patients having long term benefit, and frequent arrhythmia recurrences and patient intolerance to repeated cardioversion shocks remain a major limitation.
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specific considerations with the automatic implantable Atrial Defibrillator
Journal of Cardiovascular Electrophysiology, 1998Co-Authors: Werner Jung, Christian Wolpert, B Esmailzadeh, Susanne Spehl, S Herwig, Burghard Schumacher, Thorsten Lewalter, Heyder Omran, P G Kirchhoff, Berndt LuderitzAbstract:Introduction Internal Atrial defibrillation has been evaluated as an alternative approach to the external technique for more than two decades. Previous studies in animals and humans have shown that internal Atrial defibrillation is feasible with relatively low energies. The promising results achieved with internal Atrial defibrillation have facilitated the development of an implantable Atrial Defibrillator (IAD). Methods and results For any new therapy, it is imperative to demonstrate safety, efficacy, tolerability with improvement in quality of life, and cost-effectiveness compared with therapeutic options already available. Maintenance of sinus rhythm or prolonged duration in arrhythmia-free intervals should be demonstrated clearly with an IAD. Initial clinical experience with the Metrix system indicates stable Atrial defibrillation thresholds, appropriate R wave synchronization markers, no shock-induced ventricular proarrhythmia, and excellent detection of Atrial fibrillation (AF) with a specificity of 100%. Ventricular proarrhythmia has not been reported for correctly R wave synchronized low-energy shocks when closely coupled to RR intervals, and long-short cycles are avoided. Conclusion Preliminary experience with the Metrix system suggests that the IAD may offer a therapeutic alternative for a subgroup of patients with drug-refractory, symptomatic, long-lasting, and infrequent episodes of AF. Further efforts must be undertaken to reduce the patient discomfort associated with internal Atrial defibrillation in an attempt to make this new therapy acceptable to a larger patient population with AF.