Year : 2008 | Volume
: 11 | Issue : 2 | Page : 111--115
Transvenous, intracardial cardioversion for the treatment of postoperative atrial fibrillation
Robert D Fitzgerald1, Stefan Fritsch2, Wojciech Wislocki3, Wolfgang Oczenski3, Ferdinand R Waldenberger4, Sylvia Schwarz1,
1 Karl Landsteiner Institute for Anaesthesiology and Intensive Care Medicine and Department of Anaesthesia and Intensive Care, Hospital Hietzing, Vienna, Austria
2 Department of Cardiology, Hospital Hietzing, Vienna, Austria
3 Department of Anaesthesia and Intensive Care, Hospital Hietzing, Vienna, Austria
4 Surgical Department, Hospital Hietzing, Vienna, Austria
Robert D Fitzgerald
Karl Landsteiner Institute for Anaesthesiology and Intensive Care Medicine, Wolkersbergenstraße 1, A-1130 Vienna
Atrial fibrillation (AF) following cardiac surgery is an important factor contributing to postoperative morbidity. Transvenous, intracardial cardioversion (TIC) has been shown to be effective in the treatment of chronic AF, but is an invasive and cost-intensive procedure. However, TIC would definitely be a beneficial approach if recurrence of AF following TIC is low and pharmacological treatment could be avoided. Thus, we hypothesised that TIC would be superior to conventional treatment with amiodarone with respect to the conversion rate and recurrence of AF.
We compared TIC and conventional amiodarone therapy in a prospective, randomised and controlled trial in patients who developed AF following cardiac surgery. Twenty-three patients developed AF out of a total of 76 patients who gave written informed consent. Eighteen of these AF patients could be randomised into two equally sized groups to receive either an ALERT TM pulmonary artery catheter and TIC, or a standard pulmonary artery catheter and treatment with amiodarone. Haemodynamic parameters were registered before intervention to exclude pulmonary hypertension or fluid overload. Rates of cardioversion were compared by a Likelyhood ratio test.
Out of the nine ALERT patients, AF in five cases converted to sinus rhythm (SR) with a median of two shocks (6 J). After 24 hours however, only two patients remained in sinus rhythm. On the other hand, six of the nine patients treated with amiodarone were still in SR after 24 hours.
Whereas no difference was detectable in the conversion rate, persistence of SR following TIC was low. Thus, TIC without antiarrhythmic treatment is not recommendable for the treatment of postoperative AF.
|How to cite this article:|
Fitzgerald RD, Fritsch S, Wislocki W, Oczenski W, Waldenberger FR, Schwarz S. Transvenous, intracardial cardioversion for the treatment of postoperative atrial fibrillation.Ann Card Anaesth 2008;11:111-115
|How to cite this URL:|
Fitzgerald RD, Fritsch S, Wislocki W, Oczenski W, Waldenberger FR, Schwarz S. Transvenous, intracardial cardioversion for the treatment of postoperative atrial fibrillation. Ann Card Anaesth [serial online] 2008 [cited 2020 Jan 28 ];11:111-115
Available from: http://www.annals.in/text.asp?2008/11/2/111/39558
The occurrence of atrial fibrillation following cardiac surgery is between 26 and 41%.  Atrial fibrillation is associated with an increased rate of postoperative stroke, haemodynamic deterioration and an increased duration of hospitalisation.  Prophylactic treatment with antiarrythmic drugs has not only failed to reduce the incidence of atrial fibrillation, but also has many side effects.  Therapy with extrathoracic cardioversion has the disadvantages of necessitating anaesthesia and still requiring the application of antiarrhythmic medication as the atrial fibrillation (AF) recurrence rate is high.
Transvenous, intra-cardiac cardioversion (TIC) has been shown to be effective in the treatment of chronic atrial fibrillation resistant to other modes of therapy. , A system developed for TIC (atrial low energy reversion therapy, ALERT TM , EP MedSystems Inc., NJ, USA) is now commercially available and has been shown to be effective in the treatment of non-postoperative atrial fibrillation. , Compared to extrathoracal cardioversion, the use of this system requires no anaesthesia, but it is invasive and its application requires time and a sterile surrounding, thus excluding patients requiring instant intervention because of haemodynamic instability. Also, costs connected to the use of this device are considerably higher. While these facts sound discouraging, the system would be advantageous to patients, if no antiarrhythmic medication would be required after cardioversion. Thus, we hypothesised that intra-cardial cardioversion will produce a higher reversion rate in postoperative atrial fibrillation than the standard therapy with amiodarone. Thus, in a prospective, randomised, and controlled study, we investigated the effectiveness of this system in patients with atrial fibrillation following cardiac surgery.
Materials and Methods
Following approval by our Institutional Ethics Committee and signing a written informed consent all patients scheduled for heart surgery during the time of the investigation were routinely informed about the study and written consent was obtained from them if they approved to participate. We included patients scheduled for coronary artery bypass grafting, as well as patients who should undergo valve surgery, as these are expected to show the highest rate of postoperative atrial fibrillation.  Exclusion criteria were chronic atrial fibrillation, conduction disorders and patients with pacemakers. In total 76 patients agreed to participate in the study. Of these, 23 (30.3%) developed atrial fibrillation during the observation period (median 2.5 days after surgery; range 1-6 days). Three refused participation at that time, while two others were not included due to organisational reasons (haemodynamic instability requiring treatment before study intervention could be performed). Thus, 18 patients were finally included in the present study. Demographic data are shown in [Table 1].
During the study period, all participating patients received a multiport three-lumen central venous catheter including an introducer sheath for easy introduction of a pulmonary artery catheter (PAC) at any time during the observation period (AVA TM , Edwards Lifesciences, Irvine, CA). Anaesthesia was administered after routine management: induction was performed with midazolam, sufentanil, etomidate and pancuronium, while maintenance was by continuous infusion of sufentanil and propofol. Monitoring included measuring five-lead Electrocardiogram (ECG), arterial blood pressure, peripheral oxygen saturation and transoesophageal echocardiography. No patient required a pulmonary artery catheter for the intraoperative or immediate postoperative periods. Surgery was performed in a standardised manner with cardiopulmonary bypass and cold blood cardioplegia. Types of surgery are listed in [Table 1]. After surgery, patients were transferred to the intensive care unit (ICU) and were rapidly weaned off the ventilator. Only one patient was still intubated at the time of occurrence of atrial fibrillation, four were still in the ICU and the others encountered atrial fibrillation in the step-down unit or the regular surgical ward. All patients remained under constant ECG-monitoring for the detection of atrial fibrillation throughout the observation period (five days).
Those patients who developed AF were randomised into two groups following a computer generated randomisation list (MS Excel 4.0). Patients in both groups were allowed treatment with intravenous digoxin, if tachycardia led to haemodynamic instability at any time prior to the intervention. If this treatment was not successful in establishing haemodynamic stability and further treatment was required, patients were excluded from further evaluation. This applied to two patients.
The intervention was either performed in the ICU when the patients were still admitted, or they were brought to an operation room to allow for optimal monitoring and sterility. They either received an ALERT catheter for intra-cardiac cardioversion, or a standard pulmonary artery catheter. Mean pulmonary arterial pressure (MPAP) and pulmonary artery occlusion pressure (PAOP) were registered to exclude pulmonary hypertension or imbalances of preload. If satisfactory (as was the case in all our patients), the patients proceeded according to the randomization protocol to receive sedation with midazolam (3-5 mg i.v .) and intra-cardiac cardioversion (ALERT Group) or they were returned to the ward and treated with intravenous amiodarone (Control Group; dosage: 240 mg bolus followed by a continuous infusion of 0.6 mg/kg/h).
Non-responders from TIC received treatment according to the preference of the doctor in charge and were excluded from further evaluation.
The ALERT TM system
The ALERT TM System (EP MedSystems Inc., NJ, USA) was described in detail earlier. , In short, it incorporates a multifunctional balloon-tipped 7.5 Fr catheter that is combined with a 12-lead ECG connected to a cardioverter (Companion TM , EP MedSystems Inc, NJ, USA). The system is able to provide temporary pacing, sensing and delivery of stimuli for internal cardioversion. Pressure readings and measurement of cardiac output is possible as with a standard pulmonary artery catheter.
The catheter was introduced and its placement controlled by pressure wave monitoring. Optimal positioning would require placement of the catheter tip in the left pulmonary artery. However, as recent data supplied by the manufacturer has suggested, placement in the right pulmonary artery is almost as effective and no X-ray control of position was done to minimise patient discomfort.
The first shock was delivered with 3 J. Following each shock, a 12-lead ECG was taken to identify the sinus rhythm. In the absence of sinus rhythm, shock energy was increased by increments of 3 J to a maximum of 15 J. If no sinus rhythm was apparent even after the 15 J shock, the patient was classified as being not responsive. When fully awake and haemodynamically stable, patients were returned to the ward.
Successful cardioversion was defined as a period of sinus rhythm lasting for at least five minutes. Occurrence of sinus rhythm was registered at the time of internal cardioversion and again at 24 hours following initiation of therapy when success rate was compared between the groups.
Due to the small size of the groups, data are presented by median (range) and comparison between the groups was accomplished by Mann-Whitney U-Test. Rate of cardioversion was compared by Likelihood Ratio Test. P  Stroke and heart failure might be induced by atrial fibrillation. Thus, treatment of postoperative atrial fibrillation is regarded as an important and worthwhile measure. However, as the pathophysiology of postoperative atrial fibrillation is different from other kinds of atrial fibrillation due to high endogenous catecholamines, fluid imbalances, pericardial effusions and myocardial oedema, treatment that is effective in non-postoperative atrial fibrillations often fails in postoperative atrial fibrillation. Studies investigating the effectiveness of pharmacological treatments or prophylaxis have reported inconsistent results and patients even suffered from side effects of the drugs used.  Also, possibly transthoracic cardioversion has a reduced effectiveness ranging between 60-90% in these patients. , Thus, the development of TIC, which was found to be effective in patients with chronic atrial fibrillations not responsive to transthoracic cardioversion , and to be superior to external cardioversion,  seemed to be a promising approach for postoperative patients.
However, the method has several drawbacks, e.g ., higher costs, invasiveness and the need for sedation. Thus, to really ensure benefit, these drawbacks should be counterbalanced by an instant effect and the obviation of treatment with antiarrhythmic drugs. To investigate these questions, the authors chose a setting different from those of former studies utilising intra-cardiac cardioversion, where patients who suffered from chronic atrial fibrillation and were unresponsive to transthoracic cardioversion, experienced mostly a combination therapy of intra-cardiac cardioversion and pharmacological treatment. , However, the authors felt that due to the principal effectiveness of pharmacological treatment and the often self-limiting course of postoperative atrial fibrillation, a combination of the two treatments offers no advantage to pharmacological treatment alone.
In a randomised controlled study the authors investigated the effectiveness of transvenous, intra-cardiac cardioversion in patients developing atrial fibrillation following cardiac surgery in comparison to treatment with amiodarone. The rate of atrial fibrillation in our patients was 30.3% and thus, in the range reported in the literature. , The authors took care to identify patients with pulmonary hypertension and/or fluid imbalances leading to preload-triggered atrial fibrillation. Both mechanisms are known to decrease responsiveness to cardioversion. The groups seemed to be comparable, even when the only three females in the study were all in the ALERT Group. None of the results reported seems to be attributable to this imbalance.
The authors have to comment on the fact that the authors have not attempted to place the tip of the TIC catheter in the left pulmonary artery, as was recommended by the producer (EP Med Systems) and was done in former studies using this device. The reason was that the authors were informed by this company, that effectiveness is only diminished by a small degree if the tip is in the right pulmonary artery. This procedural change did not affect our study, as certainly our results cannot be explained by a failure to establish sinus rhythm by TIC. The conversion rate with TIC in our patients (55%) was only slightly worse than that reported for non-postoperative atrial fibrillation , and for extra-thoracic cardioversion (60-90%), , Instead the problem in this group was the fact, that sinus rhythm persisted only in two patients (22%). Thus, in the setting investigated in the present study of TIC without following pharmacological treatment, the success of this method appears to be rather small.
The problem of early recurrence of atrial fibrillation was also reported in other studies investigating the effect of postoperative cardioversion.  However, when TIC and pharmacological treatment need to be combined, a benefit for the use of the invasive and expensive TIC cannot be concluded from our results.
In contrast, treatment with amiodarone alone in the control group induced sinus rhythm in six out of nine patients (60%), which persisted in all of them. the authors have to state here that the disadvantage of the side effects of a pharmacological treatment in these patients was more than counterbalanced by the absence of any invasiveness (as the pulmonary artery catheter would not be applied regularly) and the absence of the need for sedation. Differences in patient comfort were also quite apparent to the patients. Three patients who initially consented to participate in the study, refused to do so when atrial fibrillation was detected and the procedure should have been started. Also, costs for TIC are considerable - not only for the catheter and equipment, but also for the time- and personnel-consuming nature of the procedure with the necessary precautions for sterility and monitoring.
Thus, the authors have to conclude that the use of TIC without concomitant pharmacological treatment, while able to convert some patients to sinus rhythm, is less effective in establishing persisting sinus rhythm in postoperative cardiac surgery patients, when compared to amiodarone therapy.
The authors thank the doctors and nurses of the Department of Anaesthesia and Intensive Care, Hospital Hietzing, for their help and assistance in performing this study. Furthermore, the authors thank Wolfgang Polzer MD, physician of the Department of Cardiac Surgery, and the doctors and nurses of the Department of Cardiac Surgery of our hospital for their cooperation. Also, the authors thank Claus Lamm, PhD certified statistician, for the statistical evaluation of our data.
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