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Introduction: Although there is a high prevalence of atrial arrythmias in patients with cardiovascular implantable electronic devices (CIED), few studies have compared the efficacy of cardioversion modalities for the restoration of sinus rhythm. The primary aim of this study is to compare the efficacy of internal and external first-time cardioversion for the treatment of atrial arrythmias in patients with an implantable cardioverter defibrillator (ICD), including the relative efficacy of dual and single coil leads. Methods: Demographic and clinical information was collected and analysed from consecutive electronic records of patients with a CIED who received atrial cardioversion at a single NHS trust between 2008 and 2023. Non-parametric statistical analyses were undertaken to enable the relative success of first-time cardioversion for different modalities to be determined. Results: Out of 163 patients who were identified, 71 received external and 92 received internal cardioversion. External cardioversion had the highest first-time efficacy (90.1%) with a statistically significant difference in first-time success between the external and combined internal cohorts (p = .002). Dual coil leads had superior first-time efficacy (80.4%) compared to single coil leads (56.1%), with a statistically significant difference between them (p = .022). Conclusions: First-time internal cardioversion success is superior for patients with dual coil leads compared to patients with single coil leads. There is no statistical difference between first time success for dual coil internal and external cardioversions, making an initial attempt at internal cardioversion a potentially credible clinical option for patients with dual coil leads. [ABSTRACT FROM AUTHOR]

Background: The atrial defibrillation threshold (ADFT) for internal cardioversion is theoretically related to the critical mass for sustaining atrial fibrillation (AF).Objective: This study aimed to investigate the association of ADFT for internal cardioversion with the outcome of catheter ablation for non-paroxysmal AF (non-PAF).Methods: We included 368 consecutive patients who underwent first-time catheter ablation for non-PAF. Based on the degree of ADFT recorded by the internal cardioversion before pulmonary vein isolation, we divided the patients into low ADFT (<20 J) and high ADFT (≥20 J) groups and analysed the association between ADFT and atrial tachyarrhythmia recurrence.Results: There were 234 and 134 patients in the low and high ADFT groups, respectively. Of these, 39 patients (16.7%) and 41 (30.6%) patients, respectively, had atrial tachyarrhythmia recurrence during the 2.6±1.0 year follow-up. The high ADFT group showed a significantly higher atrial tachyarrhythmia recurrence than the low ADFT group (p=0.002). This finding was also noted in patients with long-standing persistent AF (p=0.032) but not in patients with persistent AF (p=0.159). The significant predictors of arrhythmia recurrence on multivariate analysis were high ADFT (p=0.004) and long-standing persistent AF (p=0.011). In multivariate analysis within the long-standing persistent AF group, only ADFT remained a significant risk factor for AF recurrence (p=0.035).Conclusions: The high ADFT of internal cardioversion was found to be a risk factor for post-catheter ablation recurrence in patients with long-standing persistent AF but not in those with persistent AF. [ABSTRACT FROM AUTHOR]

Background: Atrial fibrillation (AF) commonly observed in patients with heart failure and cardioversion was often needed to restore the sinus rhythm. Previously, there is no study evaluating usefulness of internal cardioversion with implantable cardioverter defibrillator (ICD) device. In this study, we aimed to compare the efficacy and long-term effects of internal cardioversion with ICD devices compared to conventional external cardioversion in patients with AF and heart failure.Methods: Seventy patients with AF and heart failure who underwent electrical cardioversion were enrolled in the study. Forty patients (mean age 65.36 ± 10.37, 35 male) were assigned to undergo internal cardioversion with approximately 35 J shocks delivered through the ICD electrode. Standard external cardioversion was performed for the remaining patients (30 patients; mean age 66.20 ± 11.89; 24 male) that were similar with regard to baseline, and electrocardiographic characteristics.Results: Sinus rhythm was restored in 32 of 40 patients (80.0%) assigned to internal cardioversion compared with 25 of 30 patients (83.3%) assigned to external cardioversion (P = 0.725). We did not witness any serious complication during the procedure and hospitalization. On the follow-up, there was no statistically significant difference in recurrence of AF and incidence of major cardiovascular events between the internal and external cardioversion groups.Conclusions: Internal cardioversion with ICD device is an effective and safe method to restore sinus rhythm in heart failure patients with AF. [ABSTRACT FROM AUTHOR]

For more than 30 years transthoracic external cardioversion has been an established method for the restoration of sinus rhythm in patients with persistent atrial fibrillation. It was first described by Lown in 19631. Though the success rate for external cardioversion ranges from 60-90 %2,3,4, there is reduced efficacy in those patients with a high body-mass index and an increased transthoracic diameter 5. The method of internal cardioversion for restoration of sinus rhythm using transvenous electrodes has been reported in several animal6,7 and human studies 8,9,10,11,12,13,14,15. Cooper et al6 tested multiple electrode configurations in a sheep model of atrial fibrillation. They demonstrated that the optimal single current pathway for internal atrial defibrillation employed two electrodes that surrounded both atria (e.g., right atrial appendage and distal coronary sinus). Similar results have been reported in several human studies12,13,14. Internal cardioversion has been shown to be superior to conventional external cardioversion in terms of primary success rate, energy requirements and the need for sedation; this superiority holds especially true for patients with a high body mass index of > 25 kg/m2 and increased transthoracic diameter1

Background: Shock pain has limited the acceptance of the implantable atrial cardioverter and is a complication of ventricular implantable cardioverter-defibrillator therapy. Rounding off of the peak of a shock waveform reduces pain. Whether the pain reduction results from reduction in the peak voltage or from the rounding has not been established. In other words, does reducing the extreme dV/dt (voltage derivative) of the conventional truncated exponential capacitive discharge waveform reduce pain?Objectives: The purpose of this study was to compare the relative contributions of peak voltage and waveform shape to pain.Methods: We compared rounded and conventional waveforms with equal peak voltages. Eighty-five shocks of 50 to 500 V were delivered to 10 patients requiring atrial cardioversion for persistent atrial fibrillation. The patient touched an analog pain scale (0-15 cm) and orally reported a pain score on a scale from 0 to 5. An observer scored thoracic contractions on a scale from 0 to 5.Results: No differences between the rounded and conventional waveform on any scale were noted for either univariate or multivariate analyses. However, all three response scales were strongly predicted by voltage with r(2) = 0.77 (oral), r(2) = 0.86 (analog), and r(2) = 0.85 (contraction) after correcting for patient variability and including a log voltage term.Conclusions: Patient pain perception was determined primarily by waveform peak voltage and not by the rounding, per se. [ABSTRACT FROM AUTHOR]

KOFUNE, T.,et al.: Effect of IKr Blocker Nifekalant on Atrial Action Potential Duration After Successful Internal Cardioversion of Chronic Atrial Fibrillation. Background:Chronic atrial fibrillation (AF) is characterized by a marked decrease in the atrial effective refractory period (ERP) and in the ERP adaptation to rate as well as a decrease in the atrial conduction velocity. Little information is available about the ionic mechanisms underlying AF in humans.Materials and Methods:We studied the effect of IKr blocker nifekalant on the rate-dependent changes in atrial action potential duration in 11 patients after successful internal cardioversion of chronic AF of>2 months duration and in 7 patients without AF. In AF patients, right atrial (RA) monophasic action potential (MAP) was recorded at pacing cycle lengths (CLs) of 800–250 ms before and after administration of nifekalant. In control patients, RAMAP was recorded at CLs of 600 and 350 ms before and after administration of nifekalant.Results:Nifekalant significantly increased RAMAPD at 90% repolarization (RAMAPD90) at CLs of 800–300 ms in the AF patients. The increase in RAMAPD90 by nifekalant became significantly smaller at shorter CLs (42.5± 12.4 ms at a CL of 600 ms vs 32.8± 14.5 ms at a CL of 350 ms, P<0.05). Effect of nifekalant on RAPMAPD was attenuated at CL of 600 ms in AF patients in comparison to control patients (increase in RAMAPD in control; 73.0± 36.6 ms vs increase in RAMAPD in AF; 42.5± 12.4 ms, P<0.05); however, it was similar at a CL of 350 ms between control and AF patients.Conclusions:Electrophysiological effects of nifekalant are significantly attenuated in the chronically remodeled human atrium at slower heart rates, but the beneficial effect of RAMAPD prolongation by IKr blocker was well-preserved even at shorter CLs after chronic AF.(PACE 2005; 28:391–396) [ABSTRACT FROM AUTHOR]

Background Several pharmacological or technical factors may affect atrial defibrillation threshold (ADFT) for internal cardioversion (ICV) in the treatment of atrial fibrillation (AF). Methods We evaluated the reproducibility of ADFT in lone paroxysmal (electrically induced AF, 10 pts, 51 ± 4 years) or persistent AF (15 pts, 64 ± 7 years). The AF pattern (F–F interval) was characterised before each ICV attempt. A first step-up synchronised ICV test (ICV1, biphasic shock waveform 6 ms/6 ms) with increasing energy levels from 0.2 to 20 J was performed by a dual-lead defibrillation system (right atrium–coronary sinus configuration) connected to an external cardioverter defibrillator. After 30 min of stable sinus rhythm, a new sustained AF was induced (>20 min duration) and ICV protocol was repeated (ICV2). The AF cycle length was recorded for 30 s from the lateral wall of right atrium in basal condition and before each cardioversion attempt. Results The mean values of AF cycle length before a successful shock were similar in both AF populations (paroxysmal AF: pre-ICV1 175 ± 21 ms vs pre-ICV2 181 ± 20 ms (p=NS); persistent AF pre-ICV1 194 ± 25 ms vs pre-ICV2 202 ± 15 ms (p=NS)). No significant differences were observed between the two successful ICV tests concerning intensity, energy and impedance levels. The value of ADFT energy was reproducible in paroxysmal AF population (SD differences 1.2, coefficient of variability 9.6%). In persistent AF group only the impedance was reproducible (SD differences 2.6 Ω, coefficient of variability 4.5%), but not the energy requirements (SD differences 9.6, coefficient of variability 44.3%). Conclusions ADFT is reproducible in paroxysmal AF patients, while a high coefficient of variability is present in persistent AF, possibly related to different patterns of re-entrant circuits in the reinduced AF. This observation is important in order to evaluate factors influencing ICV-ADFT correctly in AF patients. [ABSTRACT FROM PUBLISHER]

TSE, H.-F., et al. : Clinical Predictors and Time Course of Arrhythmia Recurrence in Patients with Early Reinitiation of Atrial Fibrillation After Successful Internal Cardioversion. --> Early reinitiation of atrial fibrillation (ERAF) was commonly observed after successful electrical cardioversion, however, the effect of ERAF on the subsequent time course of arrhythmia recurrence remains unclear. The aim of this study was to evaluate the clinical predictors and time course of AF recurrence with respect to the occurrence of ERAF after successful cardioversion. The clinical predictors and time course of AF recurrence were prospectively evaluated in 124 patients (94 men, 30 women; mean age65 ± 9 years) with persistent AF (mean AF duration36 ± 40 months), who underwent internal cardioversion. After cardioversion, all patients received treatment with sotalol and were monitored for AF recurrence. Successful restoration of sinus rhythm was achieved in 104 (84%) of 124 patients. ERAF was observed in 28 (27%) of 104 patients in whom 26 of them were successfully treated acutely with intravenous sotalol and repeated cardioversion. After a mean follow‐up of 26 months, 29 (28%) of 104 patients remained in sinus rhythm. Kaplan‐Meier analysis revealed a significantly poorer outcome with regard to the recurrence of AF in patients with ERAF (hazard ratio 1.7,P = 0.03) and in those with AF for more than 3 years (hazard ratio 1.6,P = 0.03). Despite treatment with sotalol, patients with ERAF had a significantly higher AF recurrence rate within the first day (13/26 [50%] vs 12/76 [16%],P < 0.01), but not during long‐term follow‐up (21/26 [81%] vs 52/76 [68%],P = 0.3). In contrast, patients with AF for more than 3 years had a similar AF recurrence rate within the first day (7/29 [24%] vs 18/73 [25%],P = 1.0), but a significantly higher recurrence rate during long‐term follow‐up (27/29 [93%] vs 46/73 [37%],P < 0.01). In conclusion, the occurrence of ERAF and long AF duration were independent predictors for AF recurrence after successful internal cardioversion. The difference in the time course of AF recurrence in patients with ERAF from those with long AF duration suggests distinct arrhythmogenic mechanisms. (PACE 2003; 26:1809–1814) [ABSTRACT FROM AUTHOR]

Efficacy and Pain Perception of Two Biphasic Waveforms. Introduction: We evaluated the influence of the peak voltage of waveforms used for internal cardioversion of atrial fibrillation on defibrillation efficacy and pain perception. A low peak voltage biphasic waveform generated by a 500-μF capacitor with 40% tilt was compared to a standard biphasic waveform generated by a 60-μF capacitor with 80% tilt. Methods and Results: In 19 patients with paroxysmal atrial fibrillation (79% male, age 55 ± 11 years, 21% with heart disease), the atrial defibrillation threshold (ADFT) was determined during deep sedation with midazolam for both waveforms in a randomized fashion using a step-up protocol. Internal cardioversion with a single lead (shock vector: coronary sinus to right atrium) was successful in 18 (95%) of 19 patients. ADFT energy and peak voltage were significantly lower for the low-voltage waveform ( 2.1 ± 2.4 J vs 3.5 ± 3.9 J, P < 0.01; 100 ± 53 V vs 290 ± 149 V, P < 0.01 ). Sedation then was reversed with flumazenil after ADFT testing. Two shocks at the ADFT (or a 3-J shock if ADFT >3 J) were administered to the patient using each waveform in random order. Pain perception was assessed using both a visual scale and a numerical score. ADFTs were above the pain threshold in 17 (94%) of 18 patients, even though the ADFT with the 500-μF waveform was <100 V in 63% of the patients. Pain perception was comparable for both waveforms (numerical score: 6.5 ± 2.4 vs 6.3 ± 2.6 ; visual scale: 5.4 ± 2.6 vs 5.2 ± 3.1; P = NS, 500-μF vs 60-μF ). The second shock was perceived as more painful in 88% of the patients, independent of the waveform used. Conclusion: Despite a 66% lower peak voltage and a 40% lower energy, the 40% tilt, 500-μF capacitor biphasic waveform did not change the pain perceived by the patient during delivery of internal cardioversion shocks. Pain perception for internal cardioversion probably is not influenced by peak voltage alone and increases with the number of applied shocks. (J Cardiovasc Electrophysiol, Vol. 14, pp. 837-840, August 2003). [ABSTRACT FROM AUTHOR]

Although internal cardioversion is an effective method for converting AF the thromboembolic risk and bleeding complication of this procedure remains unclear. Retrospective analysis of the thromboembolic events and bleeding complications was performed in 114 consecutive patients (mean age 63 ± 10 years, 91 men) who underwent internal cardioversion for persistent AF (mean AF duration 31 ± 42 months). All patients received therapeutic warfarin for 3 weeks prior to the procedure, which was then replaced by periprocedural heparin therapy during internal cardioversion. The mean INR value before the internal cardioversion was 1.3 ± 0.2. A total of 992 R wave synchronized shocks were delivered (mean 8.7 shocks/patients) without ventricular proarrhythmia. Successful internal cardioversion of AF was achieved in 100 (88%) patients. Two (2%) patients developed major bleeding complications with pericardial effusion after the procedure. Both of them subsided with conservative treatment. Minor bleeding with wound hematoma occurred in 8 (7%) of 114 after the procedure. Overall, there was no significant difference in the risk of procedure related complication between the use of heparin infusion and subcutaneous LMWH injection (6/78 [13%] vs 3/36 [8%], P = 0.9). No thromboembolic event was observed after 4 weeks of follow-up. In conclusion, the risk of thromboembolism after discontinuation of anticoagulation before the procedure is low in patients with persistent AF underwent internal cardioversion. However, the use of periprocedural heparin therapy was associated with an increase risk of procedure related bleeding complications. [ABSTRACT FROM AUTHOR]

This study was conducted to analyze the meaning of AF frequency obtained from the surface ECG for prediction of energy requirements and early arrhythmia relapse in patients undergoing internal cardioversion of persistent AF. Nineteen consecutive patients (mean age 58 ± 11 years; 11 men, 8 women) with persistent AF (> 7 days) underwent internal cardioversion. A biphasic shock synchronized to the R wave was delivered between two catheters positioned in the high right atrium (HRA) and the coronary sinus (CS). AF frequency was estimated prior to cardioversion from surface ECG lead V1. After filtering, QRST complexes were subtracted using a template matching and averaging algorithm. The resulting fibrillatory baseline signal was subjected to Fourier transformation, displayed as a frequency power spectrum and the peak frequency was determined in the 3-12 Hz frequency band. Atrial defibrillation threshold (ADFT) was determined using a step-up protocol All patients were cardioverted successfully with a mean ADFT of 7.6 ± 6.5 J (range 0.5-25). There was a strong positive correlation between fibrillatory frequency and ADFT (R = 0.71. P = 0.001). AF recurrence within 30 days after successful cardioversion occurred in 11 (58%) patients. Receiver operating characteristic (ROC) analysis revealed a fibrillatory frequency ⩾ 7 Hz to be 64 % sensitive and 88% specific to predict AF recurrence. It was observed in 4 (36%) of 11 cases with a fibrillatory frequency < 7 Hz, as opposed to 7 (88%) of 8 cases with a fibrillatory frequency < 7 Hz (P = 0.02). Fibrillatory frequency obtained from the surface ECG predicts ADFT and early AF recurrence in patients with persistent AF undergoing internal cardioversion. [ABSTRACT FROM AUTHOR]

Internal cardioversion (ICV) has been demonstrated as an effective and safe method for restoring sinus rhythm in patients with AF. Recently, a new single lead system with a balloon-guided cardioversion catheter was introduced. ICV was performed after advancing a 7.5 Fr catheter flow-directed into the left or right pulmonary artery (PA. distal array, cathode). The proximal array (anode) was placed at the lateral RA wall. Synchronized shocks (3/3 ms biphasic impulse) were applied using a stepwise protocol (0.5, 3, 6, 9, 12, 15 J) until sinus rhythm was restored or maximum energy (15 J) was reached. Sixty-five patients (mean age 58 ± 13 years) with acute and chronic AF were included. Sinus rhythm could be restored in 59 (91 %) patients. Cardioversion success was 93% in the left PA compared to 86% in right PA. DFTs for the left and right PA approaches were 7A ± 4.0 f and 10.2 ± 4.0 J, respectively (P < 0.0001). It was significantly higher in patients with an AF history > 7 days (7.2 ± 4.1 J) than for those with a recent onset of AF (5.6 ± 4.1 J), P = 0.0012. Shock impedance differed for the left and right PA lead configuration (53 ± 11 vs 49 ± 13 Ω, P < 0.05). A right PA had configuration is as effective compared to a left PA catheter approach when performing ICV for AF. ICV with a single lead system is safe and cardioversion success is comparable to other internal and external cardioversion techniques. In combination with hemodynamic monitoring, flow-directed nonfluoroscopic catheter positioning is feasible and may serve as a valuable therapeutic and diagnostic tool in intensive care units. [ABSTRACT FROM AUTHOR]

Aim To present some safety and efficacy issues of low-energy internal cardioversion of chronic atrial fibrillation from 500 consecutive procedures performed with two different techniques, using either two single-coil catheters, or a single twin-coil catheter. Methods and Results Low-energy internal cardioversion was carried out in 368 patients by means of two defibrillation catheters: the former was positioned in the right atrium and the latter either in the left pulmonary artery (212 patients), or in the distal coronary sinus (156 patients). In the remaining 132 patients, a single twin-coil catheter was positioned with the distal coil either in the pulmonary artery (75 patients) or in the coronary sinus (57 patients), while the proximal coil was in the right atrium. The external defibrillator delivered truncated biphasic shocks (6/6 ms, tilt 50%), with a voltage of 10–400 V. In 283 patients (57%) external cardioversion had been unsuccessfully tried before low-energy internal cardioversion. After a total of 1118 shocks, the overall success rate was 92·2% (91·3% with two catheters and 94·7% with the single catheter); the success rate was 93·4 and 91·3% with the coronary sinus and the pulmonary artery approach, respectively. The mean energy used was 6·5±3·4 J (voltage: 320±45 V); no difference was found between the twin catheter (6·3±3·1 J) and the single catheter approach (6·9±3·7 J), while the coronary sinus configuration required a significantly lower energy than the pulmonary artery configuration (5·6±2·9 vs 7·2±3·8 J, P<0·05). The duration of the current atrial fibrillation episode was the only clinical characteristic statistically different between the 461 successfully cardioverted patients and the 39 failures (295 vs 727 days, P<0·01). No complication was recorded during or after the delivery of the therapy; no procedure had to be terminated because of patient's intolerance. Conclusions Low-energy internal cardioversion is a safe and effective procedure for converting chronic atrial fibrillation, confirmed by this large multicentre experience. The newly available twin-coil catheter seems to achieve a slightly better success rate compared with the traditional two-catheter technique, and is associated with the same safety profile. [ABSTRACT FROM PUBLISHER]

Background: Transvenous internal cardioversion (ICV) of atrial fibrillation (AF) may be successful after unsuccessful external CV. However, the safely and efficacy of ICV in patients with significant mitral valve disease and AF of long duration have not been evaluated prospectively. Methods: This study included 22 consecutive patients (mean age = 59 ± 14 years, 12 women) with mitral regurgitation grade = II (n = 14) or after mitral valve replacement (n = 8), who underwent ICV with 3/3 ms biphasic shocks delivered via two defibrillation catheters placed in the right atrium and the coronary sinus, respectively. The mean left atrial diameter was 53 ± 7 mm (range 45–68), and AF had been diagnosed for a median of 24 months. All patients received oral amiodarone pretreatment followed by a maintenance dose of 200 mg/day. Results: Sinus rhythm (SR) was restored by ICV in 15/20 patients (75%), and returned spontaneously in two patients during amiodarone pretreatment. The mean threshold for ICV was 6.2 ± 3.5 J. Sinus node disease was present in one patient after ICV, and two patients developed amiodarone induced hyperthyroidism. During a follow-up of 11 ± 5 months, 8 patients had recurrent AF. The remaining 11 patients who were successfully cardioverted remained in stable SR. Conclusion: SR can be safely and successfully restored by ICV in patients with MVD and long-standing AF. During intermediate-term follow-up, a significant proportion of patients remained in SR with oral amiodarone therapy. [ABSTRACT FROM AUTHOR]

This study examined the clinical, echocardiographic, and electrophysiological factors influencing the atrial defibrillation threshold (ADFT) in patients with chronic, persistent AF undergoing transvenous, low energy, atrial cardioversion. Twenty-two patients (age 57 ± 15 years) with a mean AF duration of 7.8 ± 7.1 months (range 2–32 months) underwent internal cardioversion with catheters placed in the right atrium and coronary sinus. Biphasic shocks (3/3 ms) were delivered in a step-up protocol. ADFT was defined as the lowest energy shock that converted AF to sinus rhythm. All patients were successfully cardioverted at a mean ADFT of 5.62 ± 2.82 J (range 2.6–12.9 J). Fifteen variables, including clinical characteristics (age, body mass index, AF duration, etiology), echocardiographic measurements (atrial diameter and volumes, indexes of ventricular performance), hemodynamic measurements, and mean atrial cycle during AF were analyzed as possible predictors of ADFT. In univariate regression analysis, AF duration, mean RR interval, and cardiac index correlated with ADFT. In multivariate regression analysis, AF duration remained as the only significant predictor of ADFT (B coefficient 0.311, F < 0.001; 95% confidence interval [CI] 0.194–0.427). AF duration was the most powerful predictor of ADFT. It should be considered when planning internal CV of AF to limit the number of shocks delivered. Furthermore, long intervals between AF onset and CV should be avoided. [ABSTRACT FROM AUTHOR]

Low energy internal cardioversion is a safe and highly effective method for atrial fibrillation termination. We will describe 6 patients in whom the conventional 2-electrode systems with the defibrillation leads positioned in the right atrium and in the coronary sinus or left pulmonary artery failed to terminate the arrhythmia despite the use of maximal available energies. A 3-electrode configuration including right atrium, coronary sinus and left pulmonary artery was used in order to encompass as much atrial mass as possible between the cathode and the anode. The atrial fibrillation was successfully interrupted in 4 out of 6 patients. The creation of a 3-electrode configuration may be a further technical expedient in order to increase the success rate of internal cardioversion when usual manoeuvres like lead repositioning, reversion of polarity, or addition of antiarrhythmic drugs are ineffective. [ABSTRACT FROM AUTHOR]

Background: Previous studies have shown that endocardial atrial defibrillation, using lead configurations specifically designed for ventricular defibrillation, is feasible but the substantial patient discomfort might prevent the widespread use of the technique unless significant improvements in shock tolerability are achieved. It has been suggested that the peak voltage or the peak current but not the total energy delivered determines the patient pain perception and therefore, lower defibrillating voltage and current achieved with modifications in lead and waveforms may increase shock tolerability. This study was undertaken to evaluate the effect, on the atrial defibrillation threshold (ADFT), of the addition of a patch electrode (mimicking the can electrode) to the right ventricle (RV)-superior vena cava (SVC) lead configuration. The influence of capacitor size on ADFT using the RV-SVC+skin patch configuration was also assessed. Methods: In 10 patients (pts) (Group 1) cardioversion thresholds were evaluated using biphasic shocks in two different configurations: 1) right ventricle (RV) to superior vena cava (SVC); 2) RV to SVC+skin patch. In a second group of twelve patients (Group 2) atrial defibrillation thresholds of biphasic waveforms that differed with the total capacitance (90 or 170 µF) were assessed using the RV to SVC+skin patch configuration. Results: In Group 1 AF was terminated in 10/10 pts (100 %) with both configurations. There was no significant difference in delivered energy at the defibrillation threshold between the two configurations (7.1 ± 5.1 J vs 7.1 ± 2.6 J; p < 0.05). In group 2 AF was terminated in 12/12 pts (100%) with both waveforms. The 170 µF waveform provided a significantly lower defibrillating voltage (323.7 ± 74.6 V vs 380 ± 70.2 V; p < 0.03) and current (8.1 ± 2.7 A vs 10.0 ± 2.3 A; p < 0.04) than the 90 µF waveform. All pts, in both groups, perceived the shock of the lowest energy tested (180 V) as painful or uncomfortable. Conclusions: The addition of a patch electrode to the RV-SVC lead configuration does not reduce the ADFT. Shocks from larger capacitors defibrillate with lower voltage and current but pts still perceive low energy subthreshold shocks as painful or uncomfortable. [ABSTRACT FROM AUTHOR]

Background: Despite using different electrode positions, "conventional" external DC cardioversion in patients with atrial fibrillation is ineffective in 6%-50% of cases. An alternative when DC cardioversion is not successful is low energy internal cardioversion, which is performed at increased risk. We tested the hypothesis that optimization of electrode pad position under fluoroscopy to encompass as much atrial muscle as possible might improve the success rate of external cardioversion and thus minimize the need for internal cardioversion Methods: Fifteen (9 males, 6 females) patients (age: 54 ± 15 years, weight: 124 ± 35 kg) with chronic atrial fibrillation (> 8 weeks) who had undergone unsuccessful conventional external cardioversion entered the study. Repeat conventional external cardioversion with electrodes in standard (right anterior and left posterior) positions was followed by "optimized" external cardioversion by positioning electrodes under fluoroscopy (using metallic markers). In case of failure, internal cardioversion was performed. Results: All 15 patients had undergone unsuccessful conventional external cardioversion with 360-J shocks. Eight patients (group A) reverted to sinus rhythm with one or two 360-J shocks using fluoroscopy-guided pad placement (53%). Six of the remaining 7 (86%) patients (group B) had successful internal cardioversion with biphasic shocks (12 ± 3 J). The body weight and body mass index were statistically lower in group A vs group B (106 ± 27 vs 145 ± 33 kg, p = 0.03 and 35 ± 8 vs 45 ± 8 kg/m², P = 0.48, respectively). There was no statistically significant in age, height, body surface area, duration of atrial fibrillation, amiodarone therapy, ejection fraction, or underlying heart disease. Conclusion: Unsuccessful external DC cardioversion, in some patients, is in part due to suboptimal conventional positioning of electrode pads that can be improved under... [ABSTRACT FROM AUTHOR]

Background: Based on the observation that internal cardioversion (IntCV) of atrial fibrillation is effective with electrodes in the right atrium and pulmonary artery, a new balloon-guided catheter and external defibrillation device with optional dual chamber pacing was evaluated. Methods: IntCV was attempted in 27 patients (age: 57 ± 10 years, duration: 14 ± 18 months, left atrial diameter 56 ± 8 mm) using a new defibrillation device (Alert, EP MedSystems. Inc., NJ, USA) that allows the delivery of biphasic shocks (0.5-15 J, variable tilt), atrial and ventricular pacing, and online signal recording. Pacing and defibrillation shocks were applied via a 7.5 Fr balloon-guided catheter (EP MedSystems, Inc.). Pacing, sensing, and triggering were established through the proximal atrial array and an electrode ring between both defibrillation arrays and a single ventricular electrode ring. Catheters were inserted from the antecubital vein. Results: In 25 of 27 patients sinus rhythm was restored with a mean energy of 6.7 ± 4.5 f. In five patients, atrial postshock pacing was required for bradycardia and atrial premature beats. The mean fluoroscopy time was 2.0 ± 1.3 minutes. Conclusion: The high success rate, ease of application, and backup dual chamber pacing suggest that this system is an alternative to established methods of cardioversion. In certain indications, such as failure of prior external cardioversion and situations in which a standard pulmonary balloon catheter is needed, this system would be advantageous. [ABSTRACT FROM AUTHOR]

Aims Conventional external cardioversion remains the technique of choice for restoration of sinus rhythm in patients with chronic atrial fibrillation (AF). Recent reports have suggested that internal low-energy cardioversion is efficient and safe in terminating AF in patients with failed external cardioversion. Methods and Results In 20 of 118 consecutive patients with spontaneous chronic AF (>7/days), who underwent low-energy cardioversion, one or more attempts at restoring sinus rhythm with external cardioversion had failed. Low-energy internal cardioversion was performed under light sedation. Shocks were delivered (using an external custom defibrillator) between two nonapolar catheters positioned in the right atrium (cathode) and in the coronary sinus (anode). Heart disease was present in 12 and absent in eight patients (‘lone’ atrial fibrillation). Atrial fibrillation was established for a period ranging from 12 days to 53 months. Low-energy internal cardioversion restored sinus rhythm in 15 of the 20 patients (75%) with a mean energy of 4·5 ± 1·2 J, a mean conversion voltage of 355 ± 53 V and a mean impedance of 63 ± 8 ohms. No complications were observed. With a mean follow-up of 6 ± 7 months, 11 patients (73%) were in stable sinus rhythm. Conclusions This study provides evidence in support of low-energy internal cardioversion as a valuable therapeutic option in patients in whom conventional external cardioversion failed. This technique is safe and does not require general anaesthesia. [ABSTRACT FROM PUBLISHER]

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Introduction: Clinical studies have shown that electrical conversion of atrial fibrillation (AF) is feasible with transvenous catheter electrodes at low energies. We developed a single atrial lend system that allows atrial pacing, sensing, and defibrillation to improve and facilitate this new therapeutic option. Methods and Results: The lead consists of a tripolar sensing, pacing, and defibrillation system. Two defibrillation coil electrodes are positioned on a stylet-guided lead. A ring electrode located between the two coils serves as the cathode for atrial sensing and pacing. We used this lead to cardiovert patients with acute or chronic AF. The distal coil was positioned in the coronary sinus, and the proximal coil and the ring electrode in the right atrium. R wave synchronized biphasic shocks were delivered between the two coils. Atrial signal detection and pacing were performed using the proximal coil and the ring electrode. Eight patients with acute AF (38 ± 9 rain) and eight patients with chronic AF (6.6 ± 5 months) were included. The fluoroscopy time for lead placement was 3.5 ± 4.3 minutes. The atrial defibrillation threshold was 2.0 ± 1.4 J for patients with acute AF and 9.2 ± 5.9 J for patients with chronic AF (P < 0.01). The signal amplitude detected was 1.7 ± 1.1 mV during AF and 4.0 ± 2.9 mV after restoration of sinus rhythm (P < 0.001). Atrial pacing was feasible at a threshold of 4.4 ± 3.3 V (0.5-msec pulse width). Conclusions: Atrial signal detection, atrial pacing, and low-energy atrial defibrillation using this single atrial lead system is feasible in various clinical settings. This system might lead to a simpler, less invasive approach for internal atrial cardioversion. [ABSTRACT FROM AUTHOR]

Aim Low-energy (1 to 15 J), catheter-based intracardiac cardioversion was compared with transthoracic external cardioversion (360 J) in a prospective, cross-over clinical trial. Methods and results In 187 consecutive patients with chronic atrial fibrillation, over a period of a mean of 10·0±7·3 (SD) months, 217 cardioversion attempts were made. Intracardiac shocks were randomly applied between two 6-F catheters located in either the right atrium and coronary sinus or between the right atrium and left pulmonary artery. When a cardioversion attempt with one method failed, the other method was implemented. After cardioversion, all patients were treated orally with sotalol with a mean daily dose of 174±54 mg. Conclusion Internal cardioversion is effective in restoring sinus rhythm. It might be indicated in patients in whom external cardioversion had failed or in whom external cardioversion is assumed to be difficult or even contraindicated. [ABSTRACT FROM PUBLISHER]

Copyright of Herzschrittmachertherapie und Elektrophysiologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Herzschrittmachertherapie und Elektrophysiologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Herzschrittmachertherapie und Elektrophysiologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent reports have suggested that transvenous cardioversion ofatrial fibrillation is feasible using low-energy shocks and a right atriumcoronary sinus electrode configuration. We evaluated in a prospective studythe efficacy and safety of low-energy internal cardioversion of atrialfibrillation in 104 consecutive patients. Sixty-two patients presented withchronic atrial fibrillation (group I), 16 had paroxysmal atrial fibrillation(group II), and 26 had an induced atrial fibrillation episode (group III).The mean duration of the presenting episode of atrial fibrillation was 9± 19 months for group I, 4 ± 2 days for group II, and 18± 7 minutes for group III. Atrial defibrillation was performed usingtwo intracardiac catheters: one was placed in the right atrium (cathode) andthe other in the coronary sinus or in the left branch of the pulmonaryartery (anode). The catheters were connected to a customized externaldefibrillator capable of delivering 3/3-ms biphasic waveform shocks with avoltage programmable between 10 and 400 volts. The shocks were synchronizedto the R wave. Sinus rhythm was restored in 44 of the 62 patients in group I(70%), in 12 of the 16 patients in group II (75%), and in 20of 26 patients in group III (77%). The mean voltage and energyrequired for cardioversion were respectively 300 ± 68 V and 3.5± 1.5 J, for group I, 245 ± 72 V and 2.0 ± 0.9 J forgroup II, and 270 ± 67 V and 2.6 ± 1.2 J for group III. Theleading-edge voltage required for sinus rhythm restoration was significantlyhigher (p < 0.05) in the chronic atrial fibrillation group than in theparoxysmal or induced groups. No proarrhythmic effects ocurred for thedelivered 686 R-wave synchronized shocks. This study of a large group ofpatients confirms and extends the results of previous reports. Such findingsmay have clinical implications for elective cardioversion of atrialfibrillation and the development of an implantable atrial defibrillator. [ABSTRACT FROM AUTHOR]

Transvenous internal cardioversion of chronic AF using a right atrium (RA) coronary sinus (CS) vector requires more energy than cardioversion of paroxysmal AF. Chronic AF is not terminated in 25% of patients using biphasic shocks up to 10 J. We therefore evaluated efficacy, safety, and tolerability of internal cardioversion using a "unipolar" configuration (RA to skin patch) and biphasic shocks in patients with long-lasting AF and different heart disease. In each patient, biphasic R wave synchronous shocks were delivered between a large defibrillating surface area electrode in the RA and a skin patch in the left prepectoral position. Defibrillation protocol started with a test shock of 0.4 J. Shocks were repeated and increased until termination of AF or a maximum of 34 f. Sedation was used when the patient described the shock as painful. This study included 11 patients with a mean age of 67 ± 8 years (range 56-83). AF duration was ≥ 1 month in all patients with a mean duration of 11 ±11 months (range 2-36). Underlying heart disease was present in all patients and the mean left atrial dimension was 43 ± 9 mm (range 26-57). AF was terminated in 10 of 11 patients (91 %) with a mean delivered energy of the successful shocks of 18.7 ± 8.7 f (median energy 16.9 f; range 7.3-32.5) and a mean leading edge voltage of 564 ± 129 V. The mean shock impedance at the defibrillation threshold was 71 ± 13 D, (range 59-103). A total of 131 shocks were delivered without any complication and proarrhythmia episodes. We conclude that low energy "unipolar" internal cardioversion is a simple, safe, and effective technique for termination of chronic AF in patients with heart disease. The procedure is often tolerated under light sedation. [ABSTRACT FROM AUTHOR]

High energy internal cardioversion has been proposed as an alternative method to cardiovert drug refractory or external cardioversion refractory atrial fibrillation. However, the safety of this technique has not been clearly evaluated. We reviewed findings in 53 patients who underwent 55 sessions of high energy internal cardioversion (2 patients underwent 2 sessions] for termination of longstanding atrial fibrillation. Shocks energy varied from 70-270 J. Three patients had 3 shocks during the same session, 5 had 2, and 47 only 1. Success rate was 89% (success was defined as immediate conversion to normal sinus rhythm). Low cardiac output occurred in two patients, and resulted in the death of one of these individuals, a patient with significant hypertrophic cardiomyopathy and heart failure. The other patient recovered completely. In 11% of the cases, shock induced transient atrioventricular block, necessitating ventricular pacing until sinus rhythm was restored. In three patients, a moderate but asymptomatic and uncomplicated pericardial effusion was diagnosed on echocardiogram. Finally, four patients had side effects related to venous puncture, which resolved spontaneously. These results suggest that high energy internal cardioversion is effective for conversion of atrial fibrillation. However, the technique may not be optimal in patients with advanced hypertrophic cardiomyopathy and in such cases the technique should be used carefully and only in the case of failure of external cardioversion; no more than two shocks should be delivered during the same procedure. Temporary ventricular pacing should be provided in all patients and an echocardiogram should be performed before patients are being discharged. [ABSTRACT FROM AUTHOR]

A 26-year-old man underwent an electrophysiological study for evaluation of a history of congenital heart disease, presyncope, and wide complex tachycardia. During the study the patient developed sustained atrial fibrillation with a rapid ventricular response. A 17-year-old man with a history of sick sinus syndrome developed sustained atrial fibrillation. Both patients failed four attempts at external cardioversion with a maximum delivered energy of 360 J. Low energy cardioversion was successful in both patients using biphasic waveforms and internal transvenous defibrillation electrodes. Internal cardioversion using a transvenous electrode system can be successful in patients with a trial fibrillation refractory to external cardioversion. [ABSTRACT FROM AUTHOR]

An anatomically related circumstance is reported as indication for the internal low energy cardioversion instead of an external approach. A new single lead electrode configuration is described. [ABSTRACT FROM AUTHOR]