Effect of electrode position on outcome of low-energy intracardiac cardioversion of atrial fibrillation

Treatment of Acute Atrial Fibrillation: Ventricular Rate Control and Restoration of Sinus Rhythm

Atrial fibrillation (AF) is a familiar arrhythmia seen in the emergency department and the general population. In the past it was treated in the majority of cases by controlling the ventricular rate, whether the AF is acute or chronic. However, ventricular rate control alone does not address the underlying problem and the patients still remain in AF, cardiac output and symptoms have not been optimally corrected. There is definite risk of thromboembolism. Restoration of sinus rhythm is the only way of resuming the normal conduction physiology of the heart and correcting these problems This article provides a review of the two major principles of rhythm treatment of acute AF: rate control and restoration of sinus rhythm. Transthoracic electrical cardioversion is the mainstay of treatment in haemodynamically unstable AF, whereas in stable AF, there is a choice between rate control and restoration of sinus rhythm, or they can be carried out in conjunction with each other.

Predictors of atrial fibrillation recurrence in patients with long-lasting atrial fibrillation

BACKGROUND

Limited data are available on the predictors of atrial fibrillation (AF) recurrence in patients with chronic AF.

OBJECTIVES

To evaluate potential clinical, echocardiographic and electrophysiological predictors of AF recurrence, after internal cardioversion for long-lasting AF.

METHODS

A total of 99 consecutive patients (63 men and 36 women, mean age 63.33+/-9.27 years) with long-standing AF (52.42+/-72.02 months) underwent internal cardioversion with a catheter that consisted of two defibrillating coils. Shocks were delivered according to a step-up protocol. Clinical follow-up and electrocardiographic recordings were performed on a monthly basis for a 12-month period or whenever patients experienced symptoms suggestive of recurrent AF.

RESULTS

Ninety-three patients (93.94%) underwent a successful uncomplicated cardioversion, with a mean atrial defibrillation threshold of 10.69+/-6.76 J. Immediate reinitiation of AF was observed in 15 patients (15.78%) of whom a repeated cardioversion restored sinus rhythm in 13 cases. Early recurrence of AF (within one week) was observed in 12 of 93 patients (12.90%). At the end of the 12-month follow-up period, during which seven patients were lost, 42 of the 86 remaining patients (48.84%) were still in sinus rhythm. Multivariate regression analysis showed that left atrial diameter (OR 1.126, 95% CI 1.015 to 1.249; P=0.025) and mitral A wave velocity (OR 0.972, 95% CI 0.945 to 0.999; P=0.044) were significant and independent predictors of AF recurrence, whereas age, left ventricular ejection fraction and AF cycle length were not predictive of arrhythmia recurrence.

CONCLUSION

The present study showed that the left atrial diameter and mitral A wave velocity are the only variables associated with AF recurrence after successful cardioversion.

Transvenous electrical cardioversion of atrial fibrillation in six horses using custom made cardioversion catheters

Pharmacological conversion of atrial fibrillation (AF) to sinus rhythm in horses can be difficult. The objective of this study was to investigate the feasibility of transvenous electrical cardioversion with custom made catheters in eight horses, of which three had failed cardioversion using quinidine sulfate. Two cardioversion catheters and one pacing/sensing electrode were inserted via the right jugular vein and placed using ultrasound guidance into the left pulmonary artery, the right atrium and the right ventricle, respectively. Because immediate recurrence of AF was encountered in the second horse treated, pre-treatment with amiodarone was given to each of the remaining six horses. Induction of general anaesthesia was associated with dislocation of the cardioversion catheter in three horses, requiring a second catheterisation procedure. During general anaesthesia, biphasic R wave synchronised shocks of up to 360 J were delivered between both cardioversion electrodes. In six horses (75%), including two which had failed quinidine sulfate treatment, sinus rhythm was restored with a mean energy level of 295+/-62 J. No side effects were observed. Blood analysis 3 h after cardioversion revealed normal parameters, including cardiac troponin I values. Transvenous electrical cardioversion of atrial fibrillation with custom made cardioversion catheters can be considered as a treatment option for atrial fibrillation in horses, especially when conventional drugs fail.

Improving the Acceptability of the Atrial Defibrillator:. Patient-Activated Cardioversion Versus Automatic Night Cardioversion With and Without Sedation (ADSAS 2)

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.

Impact of informed consent requirements on cardiac arrest research in the United States: exception from consent or from research?

INTRODUCTION

Research in patients with life-threatening illness such as cardiac arrest is challenging since they can not consent. The Food and Drug Administration addressed research under emergency conditions by publishing new criteria for exception from informed consent in 1996. We systematically reviewed randomized trials over a 10-year period to assess the impact of these regulations.

METHODS

Case-control study of published trials for cardiac arrest (cases) and atrial fibrillation (controls.) Studies were identified by using structured searches of MEDLINE and EMBASE from 1992 to 2002. Included were studies using random allocation in humans with cardiac arrest or atrial fibrillation prior to enrollment. Excluded were duplicate publications. Number of American trials, foreign trials and proportion of trials of American origin were compared by using regression analysis. Changes in cardiac arrest versus atrial fibrillation trials were calculated as risk differences.

RESULTS

Of 4982 identified cardiac arrest studies, 57 (1.1%) were randomized trials. The number of American cardiac arrest trials decreased by 15% (95% CI: 8, 22%) annually (P = 0.05). The proportion of cardiac arrest trials of American origin decreased by 16% (95% CI: 10, 22%) annually (P = 0.006). Of 5596 identified atrial fibrillation studies, 197 trials (3.5%) were randomized trials. The risk difference between cardiac arrest versus atrial fibrillation trials being of American origin decreased significantly (annual difference -5.8% (95% CI: -10, -0.1%), P = 0.03).

INTERPRETATION

Fewer American cardiac arrest trials were published during the last decade, when federal consent requirements changed. Regulatory requirements for clinical trials may inhibit improvements in care and threaten public health.

The effects of electrode position on the excitability of rat atria during postnatal development

Cardiac excitability is determined by the direction of the electric field, which is defined by the positioning of electrodes. However, important morphological and physiological modifications that happen during the postnatal development of the heart may affect the cardiac threshold. In this work we have evaluated the effect of electrode positioning on the excitability threshold of isolated Wistar rat atria (left auricles) during postnatal development. This was performed by determining the parameters of strength-duration curves for stimuli (rheobase, chronaxie and normalized minimum pulse energy) of atria from rats at ages (days) 5, 15, 30, 60, 90 and 120. These parameters were determined using electric field stimulation in four different orientations (apex-base, base-apex, left-right and right-left). Atrial rheobase decreased by 1.5- to 4-fold with animal age and was altered by electric field orientation in a diversified way, whereas atrial chronaxie increased only with animal age. The minimum pulse energy decreased two- to nine-fold with ageing. This was mainly due to rheobase dependence with electric field direction. We showed that the appropriate cardiac stimulation depends on the effects of three combined factors (pulse parameters, electrode position and animal age) on the atrial tissue excitability.

Atrial mechanical performance after internal and external cardioversion of atrial fibrillation: an echocardiographic study

OBJECTIVES

To compare the time course of resumption of mechanical performance of the left and right atrium after the novel method of internal low-energy cardioversion (CV) and conventional external CV of atrial fibrillation (AF).

BACKGROUND

Right atrial performance has been shown to normalize before the left atrium after external CV. However, no data on atrial function after internal CV are available.

PATIENTS AND INTERVENTIONS

Sixty-three patients with chronic AF were randomized to participate in either external or internal CV.

MEASUREMENTS

Echocardiographic examinations were carried out before as well as immediately after CV (day 0), and at days 1, 7, and 28 thereafter for the determination of cardiac dimensions, volumes, and transvalvular flow patterns.

RESULTS

After randomized internal CV or external CV, stable sinus rhythm was restored in 59 patients. Irrespective of the mode of CV, the right atrium resumed its mechanical function immediately after CV, whereas the left atrium was stunned beyond day 7. The mode of CV, internal or external, had no influence on the recovery of atrial mechanical function.

CONCLUSIONS

The right atrium resumes its normal function immediately after internal as well as external CV, whereas left atrium function is delayed. In contrast to the assumption that low-energy internal CV would impact less on atrial mechanical recovery, the type of method of CV used has no effect on such recovery.

Current clinical perspectives on implantable devices for atrial defibrillation

The role of devices that deliver shock therapy for atrial fibrillation is still debated. Following technical improvements in catheter-based atrial defibrillation, implantable devices have become available either in the form of stand-alone atrial defibrillators or in the form of dual defibrillators. Although preliminary results do not support their use as a single, unique treatment for atrial fibrillation patients, in combination with drugs, pacing or other treatments such as ablation, atrial defibrillators should help appropriately selected groups of patients.

Efficacy and safety of transvenous atrial cardioversion in patients with mitral valve disease and long-standing atrial fibrillation

BACKGROUND

Transvenous internal cardioversion (ICV) of atrial fibrillation (AF) may be successful after unsuccessful external CV. However, the safety 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.

Decreasing the number of leads required for an implantable atrial defibrillator: use of a new 2-lead system

BACKGROUND

The purpose of this study was to evaluate the use of a new 2-lead system for detection of atrial fibrillation (AF) and atrial defibrillation.

METHODS

In 16 patients undergoing elective cardioversion of AF, a 2-lead system was compared with the conventional 3-lead system in a randomized trial. The new 2-lead system consisted of a catheter with a distal bipolar right ventricular electrode pair and a proximal right atrial shock electrode coil and a separate decapolar defibrillation catheter in the coronary sinus. For the 3-lead system, an additional decapolar catheter was placed in the right atrium. AF and sinus rhythm signal amplitude detection and atrial defibrillation threshold (ADFT) were compared in each patient with both systems.

RESULTS

Successful defibrillation was obtained in all patients. ADFT for the 2-lead system was significantly higher compared with the 3-lead system (370 +/- 112 vs 316 +/- 100 V, P < .05; 9.3 +/- 5.2 vs 6.8 +/- 4.2 J, P < .05). In contrast, there was an increase in impedance for the 3-lead system (77 +/- 16 ohms vs 68 +/- 13 ohms; P < .05). AF had a lower signal amplitude compared with sinus rhythm for both systems (P < .05), and the 2-lead system had a lower signal amplitude compared with the 3-lead system for both rhythms (P < .05).

CONCLUSION

The use of a 2-lead system with this configuration is not superior to the 3-lead system regarding AF signal amplitude detection and ADFT. Further study is needed with implantable-quality leads in place of the temporary catheters used in this study.

Marked reduction in atrial defibrillation thresholds with repeated internal cardioversion

OBJECTIVES

This study was performed to assess the atrial defibrillation threshold in patients with recurrent atrial fibrillation (AF) using repeated internal cardioversion.

BACKGROUND

Previous studies in patients with chronic AF undergoing internal cardioversion have shown this method to be effective and safe. However, current energy requirements might preclude patients with longer-lasting AF from being eligible for an implantable atrial defibrillator.

METHODS

Internal shocks were delivered via defibrillation electrodes placed in the right atrium (cathode) and the coronary sinus (anode) or the right atrium (cathode) and the left pulmonary artery. After cardioversion, patients were orally treated with sotalol (mean 189 +/- 63 mg/day). Eighty consecutive patients with chronic AF (mean duration 291 +/- 237 days) underwent internal cardioversion, and sinus rhythm was restored in 74 patients. Eighteen patients underwent repeated internal cardioversion using the same electrode position and shock configuration after recurrence of AF (mean duration 34 +/- 25 days).

RESULTS

In these 18 patients, the overall mean defibrillation threshold was 6.67 +/- 3.09 J for the first cardioversion and 3.83 +/- 2.62 J for the second (p = 0.003). Mean lead impedance was 55.6 +/- 5.1 ohms and 57.1 +/- 3.7 ohms, respectively (not significant). For sedation, 6.7 +/- 2.9 mg and 3.9 +/- 2.2 mg midazolam were administered intravenously (p = 0.003), and the pain score (0 = not felt, 10 = intolerable) was 5.1 +/- 1.9 and 2.7 +/- 1.8 (p = 0.001). Uni- and multivariate analyses revealed only the duration of AF before cardioversion to be of relevance, lasting 175 +/- 113 days before the first and 34 +/- 25 days before the second cardioversion in these 18 patients (p = 0.002).

CONCLUSIONS

If the duration of AF is reduced, a significant reduction in defibrillation energy requirements for internal cardioversion ensues. This might extend the group of patients eligible for an implantable atrial defibrillator despite relatively high initial defibrillation thresholds.

Facilitating transthoracic cardioversion of atrial fibrillation with ibutilide pretreatment

BACKGROUND

Atrial fibrillation cannot always be converted to sinus rhythm by transthoracic electrical cardioversion. We examined the effect of ibutilide, a class III antiarrhythmic agent, on the energy requirement for atrial defibrillation and assessed the value of this agent in facilitating cardioversion in patients with atrial fibrillation that is resistant to conventional transthoracic cardioversion.

METHODS

One hundred patients who had had atrial fibrillation for a mean (+/-SD) of 117+/-201 days were randomly assigned to undergo transthoracic cardioversion with or without pretreatment with 1 mg of ibutilide. We designed a step-up protocol in which shocks at 50, 100, 200, 300, and 360 J were used for transthoracic cardioversion. If transthoracic cardioversion was unsuccessful in a patient who had not received ibutilide pretreatment, ibutilide was administered and transthoracic cardioversion attempted again.

RESULTS

Conversion to sinus rhythm occurred in 36 of 50 patients who had not received ibutilide (72 percent) and in all 50 patients who had received ibutilide (100 percent, P<0.001). In all 14 patients in whom transthoracic cardioversion alone failed, sinus rhythm was restored when cardioversion was attempted again after the administration of ibutilide. Pretreatment with ibutilide was associated with a reduction in the mean energy required for defibrillation (166+/-80 J, as compared with 228+/-93 J without pretreatment; P<0.001). Sustained polymorphic ventricular tachycardia occurred in 2 of the 64 patients who received ibutilide (3 percent), both of whom had an ejection fraction of 0.20 or less. The rates of freedom from atrial fibrillation after six months of follow-up were similar in the two randomized groups.

CONCLUSIONS

The efficacy of transthoracic cardioversion for converting atrial fibrillation to sinus rhythm was enhanced by pretreatment with ibutilide. However, use of this drug should be avoided in patients with very low ejection fractions.

Effect of butorphanol tartrate on shock-related discomfort during internal atrial defibrillation

BACKGROUND

In patients with atrial fibrillation, intracardiac atrial defibrillation causes discomfort. An easily applicable, short-acting analgesic and anxiolytic drug would increase acceptability of this new treatment mode.

METHODS AND RESULTS

In a double-blind, placebo-controlled manner, the effect of intranasal butorphanol, an opioid, was evaluated in 47 patients with the use of a step-up internal atrial defibrillation protocol (stage I). On request, additional butorphanol was administered and the step-up protocol continued (stage II). Thereafter, if necessary, patients were intravenously sedated (stage III). After each shock, the McGill Pain Questionnaire was used to obtain a sensory (S), affective (A), evaluative (E), and total (T) pain rating index (PRI) and a visual analogue scale analyzing pain (VAS-P) and fear (VAS-F). For every patient, the slope of each pain or fear parameter against the shock number was calculated and individual slopes were averaged for the placebo and butorphanol group. All patients were cardioverted at a mean threshold of 4.4+/-3.3 J. Comparing both patient groups for stage II, the mean slopes for PRI-T (P=0.0099), PRI-S (P=0.019), and PRI-E (P=0.015) became significantly lower in the butorphanol group than in the placebo group. Comparing patients who received the same shock intensity ending stage I and going to stage II, in those patients randomized to placebo the mean VAS-P (P=0.023), PRI-T (P=0. 029), PRI-S (P=0.030), and PRI-E (P=0.023) became significantly lower after butorphanol administration.

CONCLUSIONS

During a step-up internal atrial defibrillation protocol, intranasal butorphanol decreased or stabilized the value of several pain variables and did not affect fear. Of the 3 qualitative components of pain, only the affective component was not influenced by butorphanol. The PRI evaluated pain more accurately than the VAS.

Transvenous atrial cardioversion threshold in patients with implantable cardioverter defibrillator: influence of active pectoral can

Recent studies have shown that transvenous atrial cardioversion is feasible with lead configurations primarily designed for implantable cardioverter defibrillators (ICD). The purpose of this study was to examine the influence of an active pectoral ICD can on the atrial cardioversion threshold (ADFT). Forty consecutive patients received a transvenous single lead system (Endotak DSP 0125, CPI, St. Paul, MN, USA) in combination with a left subpectoral ICD (Ventak Mini, CPI) for treatment of malignant ventricular tachyarrhythmias. Patients were randomized into two groups: 21 received a Hot Can 1743 and 19 patients a Cold Can 1741. Step-down testing of the ventricular defibrillation threshold (VDFT) was performed intraoperatively and evaluation of the ADFT for induced atrial fibrillation (AF) at predischarge. After testing, each patient received a 2-J shock and was asked to quantify discomfort on a numerical scale ranging from 0 to 10. Both groups were comparable with regard to all clinical parameters studied. The mean VDFT in patients with a Hot Can device was significantly lower than in patients with a Cold Can (7.5 +/- 2.3 J vs 9.8 +/- 3.8 J; P < 0.03). The mean ADFT in the Hot Can group tended to be lower than in the group with Cold Cans (3.4 +/- 1.4 J vs 4.5 +/- 2.4 J; P = 0.07), and the proportion of patients in whom atrial cardioversion was accomplished at low energies (< or = 3 J) was higher in patients with active compared with patients with inactive pulse generators (57% vs 26%; P < 0.04). The mean discomfort reported after delivery of a 2-J shock was comparable in both groups (Hot Can 5.2 +/- 1.9; Cold Can: 5.3 +/- 2.1; P = NS). We conclude that the inclusion of an active left subpectoral can in the defibrillation vector of a ventricular ICD seems to reduce the energy requirements for atrial cardioversion without increasing the discomfort caused by low energy shocks.

Initial experience with a new balloon-guided single lead catheter for internal cardioversion of atrial fibrillation and dual chamber pacing

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 J. 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.

Internal right atrial cardioversion of chronic atrial fibrillation: effects of low-energy biphasic shocks

This study evaluates the efficacy and safety of internal right atrial cardioversion of atrial fibrillation using a defibrillation right atrial catheter and 2 thoracic patches with low-energy biphasic shocks.

Internal cardioversion of atrial fibrillation with a single lead configuration in a patient with massive diaphragmatic herniation

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.

Optimization of shocking lead configuration for transvenous atrial defibrillation

INTRODUCTION

High atrial defibrillation energy requirements (ADER) in patients with chronic atrial fibrillation (AF) may limit the acceptance of transvenous atrial defibrillation. We evaluated an optimized defibrillation electrode configuration that could help to reduce the ADER in patients with AF.

METHODS AND RESULTS

We tested ten different configurations in nine dogs with AF (3.33+/-2.92 days) induced by rapid atrial pacing. The configurations were: right atrial (RA) appendage as anode and coronary sinus (CS) as cathode; RA and innominate vein (I) as anode to CS (cathode); RA-CS (anode) to I (cathode); I-CS (anode) to RA (cathode); RA and left lateral subcutaneous patch (P) as anode to CS (cathode); RA-CS (anode) to P (cathode); P-CS (anode) to RA (cathode); superior vena cava (SVC) and CS (anode) to RA (cathode); RA-CS (anode) to SVC (cathode); and RA-SVC (anode) to CS (cathode). ADER was defined as the voltage needed to defibrillate the atria in 10% to 90% of 20 consecutive shocks. Three lead systems had ADER lower than the RA (anode) to CS (cathode) configuration, which required a mean of 143+/-58 volts. These three were: RA-SVC (anode) to CS (cathode) 103+/-29 V; I-CS (anode) to RA (cathode) 129+/-39 V; and P-CS (anode) to RA (cathode) 130+/-38 V. The remaining configurations had ADER higher than the RA (anode) to CS (cathode) configuration.

CONCLUSION

Adding an additional shocking electrode may reduce ADER when compared with the RA (anode) to CS (cathode) configuration. This concept could be incorporated into future implantable atrial defibrillators or used for refractory patients undergoing temporary transvenous cardioversion.

Efficacy of a new balloon catheter for internal cardioversion of chronic atrial fibrillation without anaesthesia

OBJECTIVE

To compare a new internal cardioversion system incorporated into a balloon guided catheter with a conventional two electrode system in patients with atrial fibrillation (AF).

DESIGN

Prospective study.

PATIENTS

74 patients with chronic AF treated by internal cardioversion.

MATERIALS

A 7.5 F balloon catheter with high energy electrode arrays each consisting of six 0.5 cm platinum rings. Brachial vein access enables one electrode array to be placed in the left pulmonary artery (distal pole) and the other at the lateral right atrial wall (proximal pole). The conventional two electrode system consists of 6 F electrodes placed in the proximal left pulmonary artery (anode) and the lower right atrium.

INTERVENTIONS

Internal cardioversion was performed by shocks delivered in 40 V incremental steps from an external defibrillator. Shocks were applied by the new device to 32 patients (group A) and by the conventional system to 42 patients (group B).

RESULTS

The groups differed with respect to system positioning (9.2 (7.3) upsilon 12.3 (8.1) minutes, p < 0.05) and fluoroscopy times (1.7 (1.0) v 3.3 (2.1) minutes, p < 0.01). Sinus rhythm was restored in 30 patients of group A and in 39 of group B (NS) with mean (SD) energy requirements of 8.4 (3.1) J and 7.2 (3.1) J, respectively (NS).

CONCLUSIONS

This new method of internal cardioversion has comparably high primary success rates and low sedation requirements with single and two lead systems.