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Towards Low Energy Atrial Defibrillation. SENSORS 2015; 15:22378-400. [PMID: 26404298 PMCID: PMC4610542 DOI: 10.3390/s150922378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/25/2015] [Accepted: 08/31/2015] [Indexed: 11/24/2022]
Abstract
A wireless powered implantable atrial defibrillator consisting of a battery driven hand-held radio frequency (RF) power transmitter (ex vivo) and a passive (battery free) implantable power receiver (in vivo) that enables measurement of the intracardiacimpedance (ICI) during internal atrial defibrillation is reported. The architecture is designed to operate in two modes: Cardiac sense mode (power-up, measure the impedance of the cardiac substrate and communicate data to the ex vivo power transmitter) and cardiac shock mode (delivery of a synchronised very low tilt rectilinear electrical shock waveform). An initial prototype was implemented and tested. In low-power (sense) mode, >5 W was delivered across a 2.5 cm air-skin gap to facilitate measurement of the impedance of the cardiac substrate. In high-power (shock) mode, >180 W (delivered as a 12 ms monophasic very-low-tilt-rectilinear (M-VLTR) or as a 12 ms biphasic very-low-tilt-rectilinear (B-VLTR) chronosymmetric (6ms/6ms) amplitude asymmetric (negative phase at 50% magnitude) shock was reliably and repeatedly delivered across the same interface; with >47% DC-to-DC (direct current to direct current) power transfer efficiency at a switching frequency of 185 kHz achieved. In an initial trial of the RF architecture developed, 30 patients with AF were randomised to therapy with an RF generated M-VLTR or B-VLTR shock using a step-up voltage protocol (50–300 V). Mean energy for successful cardioversion was 8.51 J ± 3.16 J. Subsequent analysis revealed that all patients who cardioverted exhibited a significant decrease in ICI between the first and third shocks (5.00 Ω (SD(σ) = 1.62 Ω), p < 0.01) while spectral analysis across frequency also revealed a significant variation in the impedance-amplitude-spectrum-area (IAMSA) within the same patient group (|∆(IAMSAS1-IAMSAS3)[1 Hz − 20 kHz] = 20.82 Ω-Hz (SD(σ) = 10.77 Ω-Hz), p < 0.01); both trends being absent in all patients that failed to cardiovert. Efficient transcutaneous power transfer and sensing of ICI during cardioversion are evidenced as key to the advancement of low-energy atrial defibrillation.
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Sankari Z, Adeli H. HeartSaver: A mobile cardiac monitoring system for auto-detection of atrial fibrillation, myocardial infarction, and atrio-ventricular block. Comput Biol Med 2011; 41:211-20. [DOI: 10.1016/j.compbiomed.2011.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 10/23/2010] [Accepted: 02/04/2011] [Indexed: 10/18/2022]
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Tse HF, Wang Q, Yu CM, Ayers GM, Lau CP. Effect of verapamil on prevention of atrial fibrillation in patients implanted with an implantable atrial defibrillator. Clin Cardiol 2009; 24:503-5. [PMID: 11450689 PMCID: PMC6655226 DOI: 10.1002/clc.4960240717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The role of verapamil in the prevention of atrial fibrillation (AF) in patients with recurrent AF is unknown. HYPOTHESIS The aim of this study was to evaluate the effect of verapamil on the prevention of AF in patients implanted with an implantable atrial defibrillator (IAD). METHODS The effects of verapamil (240 mg/day) on the total duration of AF, number of AF recurrences, and number of cardioversions were prospectively evaluated in a randomized, crossover fashion over an 8-week period in 11 patients (9 men, 2 women; mean age: 60 +/- 6 years) implanted with an IAD. RESULTS Implantable atrial defibrillators successfully converted 13 of 14 (93%) spontaneous episodes of AF. There was no significant difference in the efficacy of cardioversion (86 vs. 100%, p = 0.8), the total duration of AF (173 +/- 198 vs. 270 +/- 241 h, p = 0.5), the number of AF episodes (8.5 +/- 9.0 vs. 9.3 +/- 10.2, p = 0.3), and the number of cardioversions (1.7 +/- 2.4 vs. 1.8 +/- 2.1 p = 0.7) with or without treatment with verapamil. CONCLUSIONS The results of the present study suggest that treatment with verapamil has no significant effect on the prevention of AF in patients treated with an LAD.
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Affiliation(s)
- H F Tse
- Division of Cardiology, Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong, China
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Boriani G, Diemberger I, Biffi M, Martignani C, Ziacchi M, Bertini M, Valzania C, Bronzetti G, Rapezzi C, Branzi A. How, why, and when may atrial defibrillation find a specific role in implantable devices? A clinical viewpoint. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2007; 30:422-33. [PMID: 17367364 DOI: 10.1111/j.1540-8159.2007.00685.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
This viewpoint article discusses the potential for incorporation of atrial defibrillation capabilities in modern multi-chamber devices. In the late 1990s, the possibility of using shock-only therapy to treat selected patients with recurrent atrial fibrillation (AF) was explored in the context of the stand-alone atrial defibrillator. The failure of this strategy can be attributed to the technical limitations of the stand-alone device, low tolerance of atrial shocks, difficulties in patient selection, a lack of predictive knowledge about the evolution of AF, and, last but not least, commercial considerations. An open question is how atrial defibrillation capability may now assume a specific new role in devices implanted for sudden death prevention or cardiac resynchronization. For patients who already have indications for implantable devices, device-based atrial defibrillation appears attractive as a "backup" option for managing AF when preventive pharmacological/electrical measures fail. This and several other personalized hybrid therapeutic approaches await exploration, though assessment of their efficacy is methodologically challenging. Achievement of acceptance by patients is an essential premise for any updated atrial defibrillation strategy. Strategies that are being investigated to improve patient tolerance include waveform shaping, pharmacologic modulation of pain, and patient-activated defibrillation (patients might also perceive the problem of discomfort somewhat differently in the context of a backup therapy). The economic impact of implementing atrial defibrillation features in available devices is progressively decreasing, and financial feasibility need not be a major issue. Future studies should examine clinically relevant outcomes and not be limited (as occurred with stand-alone defibrillators) to technical or other soft endpoints.
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Affiliation(s)
- Giuseppe Boriani
- Institute of Cardiology, University of Bologna, Azienda Ospedaliera S. Orsola-Malpighi, Bologna, Italy.
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Santini L, Forleo GB, Topa A, Romeo F, Santini M. Electrical cardioversion of atrial fibrillation: different methods for a safe and effective technique. Expert Rev Cardiovasc Ther 2006; 3:601-10. [PMID: 16076271 DOI: 10.1586/14779072.3.4.601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Atrial fibrillation is the most common cardiac arrhythmia observed in clinical practice. Many different therapeutic approaches are available at present but none may be considered the gold standard treatment. Antiarrhythmic drugs are not very effective agents to cardiovert persistent atrial fibrillation and, therefore, the technique most frequently used to restore sinus rhythm is external direct current cardioversion, which has proved to be safe and very effective. Esophageal cardioversion is an alternative method that could obviate some of the limitations of the external technique, such as the high energy required, need for anesthesia and longer hospital stay. Another technique performed during the last two decades is internal cardioversion, but at present, the advantage of this technique is limited to the small proportion of cases of unsuccessful external cardioversion.
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Affiliation(s)
- Luca Santini
- University Hospital of Tor Vergata, Cardiology Department, Rome, Italy.
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6
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Boodhoo L, Mitchell A, Ujhelyi M, Sulke N. Improving the Acceptability of the Atrial Defibrillator:. Patient-Activated Cardioversion Versus Automatic Night Cardioversion With and Without Sedation (ADSAS 2). PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2004; 27:910-7. [PMID: 15271009 DOI: 10.1111/j.1540-8159.2004.00558.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Acceptability of the atrial defibrillator is partly limited by concerns about shock related anxiety and discomfort. Sedation and/or automatic cardioversion therapy during sleep may ease shock discomfort and improve patient acceptability. Three atrial cardioversion techniques were compared: patient-activated cardioversion with sedation, automatic night cardioversion with sedation, and automatic night cardioversion without sedation. Sedation was oral midazolam (15 mg). Fifteen patients aged 60 +/- 13 years were assigned each strategy randomly for three consecutive episodes of persistent atrial fibrillation requiring cardioversion. Patients completed questionnaires for multiple parameters immediately and again at 24 hours postcardioversion. Atrial cardioversion strategies with oral sedation (patient-activated and automatic) significantly reduced shock recall by 77% (P < 0.005), therapy dissatisfaction by 57%-71% (P < 0.03), shock discomfort by 61%-73% (P < 0.01), shock pain by 79%-83% (P < 0.001), and shock intensity by 73%-77% (P < 0.03), compared to automatic night cardioversion without sedation (P < 0.02). Atrial shock pain was short-lived and caused little disruption to the patients' daily routines. Automatic night cardioversion without sedation, resulted in sleep disturbances not seen with the other strategies (42% vs 0%, P < 0.001) as well as concerns about future pain or discomfort. Twelve patients (80%) chose patient-activated cardioversion with sedation as their preferred treatment, and three (20%) remainder chose automatic night cardioversion with sedation. Ninety percent of patients chose automatic night cardioversion without sedation as the least acceptable therapy. Sedation significantly increases atrial shock acceptability regardless of cardioversion method. Shocks without sedation are significantly less acceptable to patients using the atrial defibrillators.
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Affiliation(s)
- Lana Boodhoo
- Department of Cardiology, Eastbourne General Hospital, Eastbourne, England.
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7
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Tse HF, Lau CP. Future prospects for implantable devices for atrial defibrillation. Cardiol Clin 2004; 22:87-100, ix. [PMID: 14994850 DOI: 10.1016/s0733-8651(03)00114-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The success of the implantable cardioverter defibrillator (ICD) led to the concept of a device that would terminate atrial fibrillation (AF) using an implantable device. Implantable devices for AF are undergoing rapid evolution. Currently used devices combine pacing and cardioversion therapies to prevent and to treat AE Recent studies have shown that these devices are safe and can decrease the incidence of AF and improve quality of life significantly. Implantable devices for atrial defibrillation are likely to have an increasing role in the near future, particularly when they are used in combination with ICD and cardiac resynchronization therapy in which AF is both common and its termination is clinically beneficial.
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Affiliation(s)
- Hung-Fat Tse
- Cardiology Division, Department of Medicine, The University of Hong Kong, 19/F, Block K, Queen Mary Hospital, Pokfulam Road, Hong Kong, China
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Wolpert C, Jung W, Spehl S, Schimpf R, Omran H, Schumacher B, Esmailzadeh B, Tenzer D, Mehra R, Lüderitz B. Incidence and rate characteristics of atrial tachyarrhythmias in patients with a dual chamber defibrillator. Pacing Clin Electrophysiol 2003; 26:1691-8. [PMID: 12877702 DOI: 10.1046/j.1460-9592.2003.t01-1-00254.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Atrial tachyarrhythmias play an important role in the treatment of patients with malignant ventricular tachyarrhythmias not only with respect to inappropriate discharges but also to left ventricular function and stroke risk. A combined dual chamber defibrillator provides separate therapies for atrial and ventricular tachyarrhythmias. To assess the incidence of atrial tachyarrhythmias in patients with this dual chamber implantable defibrillator, 40 patients with ventricular tachyarrhythmias and concomitant atrial tachyarrhythmias and/or AV conduction disturbances were included in a prospective study. During a mean follow-up of 25 +/- 11 months, 26 of 40 patients had a total of 1,430 recurrences of atrial tachyarrhythmias. The vast majority of the atrial tachyarrhythmias with regular atrial cycles had a mean median atrial cycle length of 235 +/- 37 ms and a mean duration of 34 +/- 144 minutes. Atrial tachyarrhythmias with irregular atrial cycles exhibited a median atrial cycle length of 198 +/- 31 ms and had a mean duration of 246 +/- 1,264 minutes. In addition, 67% of 375 tachyarrhythmias, in which the median ventricular cycle length during the ongoing episode could be documented, had a ventricular rate <100 beats/min. Continuous atrial arrhythmia detection with a dual chamber ICD reveals a high incidence of atrial tachyarrhythmias with a predominantly short duration of paroxysmal recurrences <1 hour in the vast majority of episodes.
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Abstract
The dose-response relationship for successful defibrillation has been determined in man for the ventricle but not for the atrium. The purpose of this study was to determine the dose-response relationship for internal atrial defibrillation in humans. Seventy-seven consecutive patients underwent internal atrial defibrillation for acute (n = 14) or chronic AF (n = 63). Shocks were delivered in 40-V increments between electrodes positioned in the coronary sinus and the right atrium until successful conversion or a maximum of 400 V was reached. The shock strength versus success of shock data were subjected to a Kaplan-Meier survival analysis combined with a nonparametric probability analysis to arrive at the dose-response relationship. Using this relationship, comparisons were made between acute and chronic AF and clinical relevant conversion percentages (20, 50, 80 and 95%) were estimated and were compared with the conventional mean threshold. There were significant dose-response relationships in both patients groups (P < 0.05). The Kaplan-Meier analysis comparing patients with chronic and acute AF showed significant differences in their dose-response relationships (P < 0.001). The estimated shock intensity for 95% conversion in patients with acute and chronic AF was 279 V (2.9 J) and 433 V (6.6 J), respectively (P < 0.001). The conventional mean defibrillation threshold in patients with acute (192 +/- 15 V. 1.4 +/- 0.2 J) and chronic AF (343 +/- 8 V, 4.4 +/- 0.2 J) predicted the 60% and 45% chance of successful conversion, respectively. In conclusion, this study demonstrates that single shock conversion data can be used to determine a dose-response relationship, which can be used to estimate the shock intensity required for specific successful atrial defibrillation efficacy and to compare different clinical factors that affect defibrillation efficacy.
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Affiliation(s)
- Hung-Fat Tse
- Cardiology Division, Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
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Everett TH, Kok LC, Vaughn RH, Moorman JR, Haines DE. Frequency domain algorithm for quantifying atrial fibrillation organization to increase defibrillation efficacy. IEEE Trans Biomed Eng 2001; 48:969-78. [PMID: 11534845 DOI: 10.1109/10.942586] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We hypothesized that frequency domain analysis of an interatrial atrial fibrillation (AF) electrogram would show a correlation of the variance of the signal and the amplitude of harmonic peaks with the periodicity and morphology (organization) of the AF signal and defibrillation efficacy. We sought to develop an algorithm that would provide a high-resolution measurement of the changes in the spatiotemporal organization of AF. AF was initiated with burst atrial pacing in ten dogs. The atrial defibrillation threshold (ADFT50) was determined, and defibrillation was repeated at the ADFT50. Bipolar electrograms from the shocking electrodes were acquired immediately preshock, digitally filtered, and a FFT was performed. The organization index (OI) was calculated as the ratio of the area under the first four harmonic peaks to the total area of the spectrum. For a 4-s window, the mean OI was 0.505 +/- 0.087 for successful shocks, versus 0.352 +/- 0.068 for unsuccessful shocks (p < 0.001). Receiver operator characteristic (ROC) curve analysis was used to determine the optimal sampling window for predicting successful shocks. The area of the ROC curve was 0.8 for a 1-s window, and improved to 0.9 for a 4-s window. We conclude that the spectrum of an AF signal contains information relating to its organization, and can be used in predicting a successful defibrillation.
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Affiliation(s)
- T H Everett
- Department of Internal Medicine, University of Virginia Health System, Charlottesville 22908, USA
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11
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Abstract
Significant advances have been made in the management of cardiac arrhythmias. New technology has enhanced the ability to understand and treat a variety of tachycardias. Excitement and caution surround ablative approaches for atrial fibrillation. The role of ICDs and class III antiarrhythmic drugs in the management of patients at risk for sudden cardiac death has been clarified. A new indication for cardiac pacing is evolving as a supplemental treatment for patients with refractory congestive heart failure. These and other advances provide numerous exciting options for management of cardiac patients.
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Affiliation(s)
- L Fei
- Division of Cardiovascular Disease and Critical Care Medicine, Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois, USA
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12
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Tse HF, Wang Q, Yu CM, Ayers GM, Lau CP. Time course of recovery of left atrial mechanical dysfunction after cardioversion of spontaneous atrial fibrillation with the implantable atrial defibrillator. Am J Cardiol 2000; 86:1023-5, A10. [PMID: 11053721 DOI: 10.1016/s0002-9149(00)01143-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effect of the timing of cardioversion of atrial fibrillation on left atrial mechanical function was studied in 11 patients treated with the implantable atrial defibrillator. Results of this study suggested that prompt cardioversion of spontaneous episodes of atrial fibrillation within 48 hours after onset was associated with early resolution of left atrial mechanical dysfunction seen after cardioversion.
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Affiliation(s)
- H F Tse
- Department of Medicine, and the Institute of Cardiovascular Science and Medicine, University of Hong Kong, Queen Mary Hospital, China
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13
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Timmermans C, Lévy S, Ayers GM, Jung W, Jordaens L, Rosenqvist M, Thibault B, Camm J, Rodriguez LM, Wellens HJ. Spontaneous episodes of atrial fibrillation after implantation of the Metrix Atrioverter: observations on treated and nontreated episodes. Metrix Investigators. J Am Coll Cardiol 2000; 35:1428-33. [PMID: 10807443 DOI: 10.1016/s0735-1097(00)00579-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVES We sought to evaluate the number and duration of device-treated and self-terminating, nontreated episodes of atrial fibrillation (AF) after implantation of the Metrix Atrioverter. BACKGROUND A recent study has shown that the Atrioverter can rapidly restore sinus rhythm in patients with AF; however, the effect of the device on the clinical course of the arrhythmia in these patients is unknown. METHODS The Atrioverter was implanted in 51 patients with symptomatic, recurrent, drug-refractory AF. The device was programmed to periodically monitor the cardiac rhythm. Defibrillation of AF episodes was performed under physician observation. RESULTS During a mean follow-up of 260 +/- 144 days, 1,161 episodes of AF were observed during valid monitoring periods in 45 of 51 patients. Forty-one patients experienced 231 episodes for which they sought defibrillation therapy. The average duration of the treated episodes during valid monitoring periods (190 of 231 episodes in 39 of 41 patients) was significantly longer than that of the nontreated episodes (38 +/- 44 vs. 10 +/- 8 h; p < 0.05). The time between episodes requiring Atrioverter therapy increased, and the risk of having an episode requiring treatment decreased. No changes were observed in the number and duration of the short-lasting, nontreated episodes as time since implantation of the device increased. CONCLUSIONS In patients with symptomatic, recurrent, drug-refractory AF, the frequency of long-lasting episodes, which were treated under observation with repeated defibrillation using the Atrioverter, decreased. The number and duration of short-lasting, nontreated episodes did not change during the 20-month study period. The effect of ambulatory use of the device on the recurrence of short-lasting episodes needs to be evaluated.
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Affiliation(s)
- C Timmermans
- Department of Cardiology, Academic Hospital, Maastricht, The Netherlands.
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14
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A century of cardiac arrhythmias. J Am Coll Cardiol 2000. [DOI: 10.1016/s0735-1097(00)80049-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
External cardioversion of AF is an established and accepted method for termination of individual episodes of AF. Recent advances have taken place in the area of non-pharmacologic management of AF, and despite its long history and well established technique, defibrillation has not been spared from these advances. The success of low-energy internal atrial defibrillation for the termination of both chronic and acute onset atrial fibrillation has resulted in the development of implantable defibrillators that treat this arrhythmia. Many of the advances have come about as a result of the use of defibrillation in implanted devices for recurrent AF due to the substantial efforts in an attempt to make this form of restoration of sinus rhythm more efficacious and tolerable to the patient. Additionally, the use of other non-pharmacologic control of atrial fibrillation has also been recently explored, namely the use of ablation and atrial pacing. The use of these other non-pharmacologic therapies are likely to both reduce the recurrence rate, as well as enhance the efficacy of defibrillation. However, defibrillation is likely to still be needed to terminate atrial fibrillation for persistent episodes, and its combination with these other therapies is likely synergistic. Electrical therapy to restore sinus rhythm for persistent episodes of atrial fibrillation is likely to be perceived by the patient. Therefore, the concept of patient controlled therapy from implanted devices to treat atrial fibrillation has shown promising results and will likely be a requirement of such devices in the future. Major advances in defibrillation therapy for atrial fibrillation have been made and have resulted in the development of implantable atrial defibrillators. Despite these advances in defibrillation and other therapies for atrial fibrillation, it is likely that combined pharmacologic and non-pharmacologic therapies for atrial fibrillation will prevail over the individual entities themselves. Future study is needed to determine the best therapy or combination of therapies for individual patients with atrial fibrillation.
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Affiliation(s)
- G M Ayers
- Corvascular Inc., Palo Alto, CA 94306, USA.
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Tse HF, Lau CP. Safety and efficacy of internal cardioversion of atrial fibrillation in patients with impaired left ventricular systolic function. Am J Cardiol 1999; 84:1090-2, A9. [PMID: 10569672 DOI: 10.1016/s0002-9149(99)00507-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In patients with structural heart disease and left ventricular ejection fraction <40%, internal cardioversion is a safe and effective method for converting persistent atrial fibrillation. The acute success rate and atrial defibrillation requirement for cardioversion in these patients is comparable to patients with lone atrial fibrillation and structurally normal hearts.
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Affiliation(s)
- H F Tse
- Department of Medicine, University of Hong Kong, Queen Mary Hospital, China
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Tse HF, Lau CP, Camm AJ. Transvenous atrial defibrillation--techniques and clinical applications. Clin Cardiol 1999; 22:614-22. [PMID: 10526684 PMCID: PMC6655977 DOI: 10.1002/clc.4960221005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/1998] [Accepted: 02/09/1999] [Indexed: 11/09/2022] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia requiring treatment. The most desirable therapy may be restoration and maintenance of sinus rhythm. Limitations of the current methods for cardioversion of AF have prompted the development of transvenous atrial defibrillation (TADF) as an alternative and more effective technique for converting AF. Recent advances in the technique of TADF, particularly in the design and configuration of the electrodes, and the use of an optimal biphasic shock waveform have dramatically improved the efficacy of TADF for the termination of all types of AF. The reduction in voltage and energy requirements for cardioversion by TADF may allow the procedure to be performed with little or no sedation and the risk of general anesthesia may be avoided. Both experimental and clinical studies have demonstrated the feasibility, safety, and efficacy of using TADF as a new temporary or "permanent" mode of electrical therapy for AF. It has several potential applications, from acute termination of AF in the electrophysiology laboratory and in patients who have failed to respond to external cardioversion, to its use as an implantable device for treating recurrent AF. This article reviews the current technique and clinical applications of TADF for treatment of AF.
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Affiliation(s)
- H F Tse
- Department of Medicine, University of Hong Kong, Queen Mary Hospital, China
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Tse HF, Lau CP, Yu CM, Lam TF, Leung SK, Ayers GM. Experience with a single-pass, dual-electrode implantable atrial defibrillator lead for maintaining sinus rhythm in patients with recurrent atrial fibrillation. Am J Cardiol 1999; 84:606-8, A9. [PMID: 10482167 DOI: 10.1016/s0002-9149(99)00390-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The implantable atrial defibrillator is a new potential nonpharmacologic treatment for recurrent atrial fibrillation. The results of this study suggest that a simplified lead configuration, with a single-pass, dual-electrode atrial defibrillation lead can be used for both atrial fibrillation detection and defibrillation with an implantable atrial defibrillator.
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Affiliation(s)
- H F Tse
- Department of Medicine, University of Hong Kong, Queen Mary Hospital, China
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Tse HF, Lau CP, Yu CM, Lee KL, Michaud GF, Knight BP, Morady F, Strickberger SA. Effect of the implantable atrial defibrillator on the natural history of atrial fibrillation. J Cardiovasc Electrophysiol 1999; 10:1200-9. [PMID: 10517652 DOI: 10.1111/j.1540-8167.1999.tb00296.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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 had no cardiovascular disease, 5 patients had hypertension, 3 patients had coronary heart disease, and 1 patient had 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, all 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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Affiliation(s)
- H F Tse
- Department of Medicine, University of Hong Kong, Queen Mary Hospital, China
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Abstract
OBJECTIVES We examined the feasibility and efficacy of using a single-pass, dual-electrode (Solo) lead for atrial fibrillation (AF) detection and defibrillation. BACKGROUND The efficacy and safety of an implantable atrial defibrillator (IAD) has been extensively studied; however, separate right atrial (RA) and coronary sinus (CS) defibrillation leads are used for the present system. METHODS We studied the use of the Solo lead for AF detection and defibrillation in 17 patients who underwent cardioversion of chronic AF. The Solo lead with a proximal 6-cm RA electrode and a distal 6-cm spiral-shaped CS electrode were positioned into the CS with the RA electrode against the anterolateral RA wall. The RA-CS electrogram signal amplitudes were measured and the efficacy of the Solo lead for AF detection and defibrillation was assessed by using an external version of the IAD. RESULTS The leads were inserted in all patients without complication (mean fluoroscopy time: 13.3+/-6.8 min). The mean RA-CS signal amplitude was 484+/-229 microV during sinus rhythm and 274+/-88 microV during AF (p < 0.05). All patients had satisfactory atrial signal amplitude to allow accurate detection of sinus rhythm. Successful cardioversion was achieved in 16/17 (94%) patients with an atrial defibrillation threshold of 320+/-70 V (5.5+/-2.7 J). Insufficient interelectrode spacing resulted in suboptimal electrode locations, associated with a lower atrial signal amplitude, a higher atrial defibrillation threshold and diaphragmatic stimulation. CONCLUSIONS These results suggest a simplified lead configuration with optimal interelectrode spacing can be used with an IAD for AF detection and defibrillation.
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Affiliation(s)
- H F Tse
- Department of Medicine, University of Hong Kong, Queen Mary Hospital, China
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