Thoracoscopic Atrial Fibrillation Ablation Research Articles

Totally Thoracoscopic Pulmonary Vein Isolation: A Simplified Technique.

Since the introduction of thoracoscopic ablation for atrial fibrillation (AF), the field of minimally invasive AF treatment has evolved toward an established treatment option for AF, with an overall 2-year antiarrhythmic drug free success rate of 77%. Complications are usually minor, and the incidence of bleeding needing conversion to sternotomy or (mini-)thoracotomy varies between 0% and 1.6%. Bleeding is often related to encircling the pulmonary veins, which is a blind maneuver that has to be done without direct camera vision. We propose here a modified surgical technique to simplify the procedure, shorten the operating time, and lower the risk of complications.

Thoracoscopic ablation of atrial fibrillation – Should we still be concerned about periprocedural complications?

IntroductionMinimally invasive surgical ablations are becoming an interesting treatment option for patients with stand-alone atrial fibrillation (AF). However, they are in general connected with higher rates of perioperative complications. The aim of this study was to summarize the complications of all such procedures performed in our center and compare them with similar recent papers. Material and methodsAll perioperative and 30-days complications of thoracoscopic ablations of AF performed in our center were collected and analyzed. Recent literature was searched for studies describing the outcomes of thoracoscopic and hybrid ablations. Rates of complications were then compared with our outcomes and also with catheter ablations. ResultsA total of 112 patients underwent a thoracoscopic ablation of AF in our center between 2006 and 2017, with use of three different devices. Mean age was 61.4±8.8 years, 66% were males and 53% of patients had long-standing persistent AF. A life-threatening complications occurred in 2 (1.8%) patients, including 1 conversion to sternotomy and 1 stroke. Severe complications occurred in 6 (5.4%) patients including 2 re-explorations for bleeding, 3 cases of phrenic nerve palsy and 1 respiratory failure. A minor od moderate complications occurred in 17 (15.2%) patients. Twenty-seven suitable papers were identified in recent literature for comparison (total of 1869 patients). The rates of significant complications varied between 0 and 16% over different centers, mean rate was 4.8%. Regarding the catheter ablation studies, 5–7% of patients suffer from some severe complication after ablation of AF. ConclusionsRates of 30-days, life-threatening and severe complications are comparable between mini-invasive surgical and catheter ablations of AF. Rates of minor complications appear to be higher in surgical ablations. To keep the rates low or even to decrease them, those surgical or hybrid procedures should be performed in experienced centers.

Risk of Intraatrial Thrombi After Thoracoscopic Ablation in Absence of Heparin and Appendage Closure

Catheter and surgical ablation of atrial fibrillation (AF) can be associated with a risk of thromboembolic events. The goal of this study was to assess optimal anticoagulation management during thoracoscopic ablation of AF. Fifty-two patients with persistent or long-standing persistent AF underwent hybrid ablation consisting of thoracoscopic ablation followed by electrophysiologic (EP) evaluation and consecutive ablation if indicated. The thoracoscopic ablation was performed using three different anticoagulation protocols: (1) without periprocedural heparin and without occlusion of the left atrial appendage; (2) with periprocedural heparin but without left atrial appendage occlusion; and (3) with periprocedural heparin and left atrial appendage occlusion. Transesophageal echocardiography (TEE) was obligatorily used to screen for intraatrial thrombi before the surgical and EP procedure and before hospital discharge for patients in protocols 2 and3. In group 1 (n= 20), 1 patient (5%) had a postoperative stroke with persistent neurologic deficit, and 6 other patients (30%) had a new thrombus in the left atrial appendage seen on the pre-EP TEE. In group 2(n=6), 3 left atrial appendage thrombi occurred (50%; 2on predischarge TEE and 1 on pre-EP TEE). In group 3(n= 26), no intracardiac thrombi were found on predischarge and pre-EP TEE, and there were no strokes in this group of patients, namely, the rates of thrombus or stroke were significantly reduced when compared with groups 1and 2 (p= 0.001). Thoracoscopic ablation of AF can be associated with a risk of left atrial appendage thrombus formation and possibly also stroke. With administration of heparin during the ablation, followed by occlusion of the left atrial appendage as a part of the procedure, this risk can be effectively reduced.

PITX2 Modulates Atrial Membrane Potential and the Antiarrhythmic Effects of Sodium-Channel Blockers

BackgroundAntiarrhythmic drugs are widely used to treat patients with atrial fibrillation (AF), but the mechanisms conveying their variable effectiveness are not known. Recent data suggested that paired like homeodomain-2 transcription factor (PITX2) might play an important role in regulating gene expression and electrical function of the adult left atrium (LA). ObjectivesAfter determining LA PITX2 expression in AF patients requiring rhythm control therapy, the authors assessed the effects of Pitx2c on LA electrophysiology and the effect of antiarrhythmic drugs. MethodsLA PITX2 messenger ribonucleic acid (mRNA) levels were measured in 95 patients undergoing thoracoscopic AF ablation. The effects of flecainide, a sodium (Na+)-channel blocker, and d,l-sotalol, a potassium channel blocker, were studied in littermate mice with normal and reduced Pitx2c mRNA by electrophysiological study, optical mapping, and patch clamp studies. PITX2-dependent mechanisms of antiarrhythmic drug action were studied in human embryonic kidney (HEK) cells expressing human Na channels and by modeling human action potentials. ResultsFlecainide 1 μmol/l was more effective in suppressing atrial arrhythmias in atria with reduced Pitx2c mRNA levels (Pitx2c+/–). Resting membrane potential was more depolarized in Pitx2c+/– atria, and TWIK-related acid-sensitive K+ channel 2 (TASK-2) gene and protein expression were decreased. This resulted in enhanced post-repolarization refractoriness and more effective Na-channel inhibition. Defined holding potentials eliminated differences in flecainide’s effects between wild-type and Pitx2c+/– atrial cardiomyocytes. More positive holding potentials replicated the increased effectiveness of flecainide in blocking human Nav1.5 channels in HEK293 cells. Computer modeling reproduced an enhanced effectiveness of Na-channel block when resting membrane potential was slightly depolarized. ConclusionsPITX2 mRNA modulates atrial resting membrane potential and thereby alters the effectiveness of Na-channel blockers. PITX2 and ion channels regulating the resting membrane potential may provide novel targets for antiarrhythmic drug development and companion therapeutics in AF.

Treatment of stand-alone atrial fibrillation with a right thoracoscopic approach employing a microwave or monopolar radiofrequency energy source: long-term results.

Minimally invasive surgery for atrial fibrillation (AF) has rapidly evolved recently. The long-term efficacy of most of these procedures is poorly known. Between 2006 and 2010, 38 drug-resistant, symptomatic patients with stand-alone AF underwent unilateral, thoracoscopic, off-pump ablation. The mean age was 60 ± 8.2 (range 42-75) years and the mean AF duration was 46 ± 62 (range 3-240) months. Sixteen patients (42%) had paroxysmal, 9 (24%) had persistent and 13 (34%) had long-standing persistent AF. A box lesion was created using a microwave (26 patients) or monopolar radiofrequency (12 patients) system. Patients were prospectively followed with repeat electrocardiograms (ECGs) and ECG Holters. Additional catheter ablation was offered to patients with recurrence of arrhythmia. All procedures were completed as planned with one conversion to sternotomy, zero mortality and minimal in-hospital complications. The mean follow-up duration was 70 ± 19 (range 20-88) months. Arrhythmia-free survival rates after the procedure were 50, 44.4, 24.1 and 10.8% at 6, 12, 36 and 60 months, respectively, with most recurrences in the first 6 months. Twelve patients underwent additional catheter ablation(s); from the last intervention, 75% of them were in sinus rhythm (SR) with a mean follow-up of 31 ± 23 (range 4-86) months. Overall, at the end of follow-up, only 3 patients were still in SR without any arrhythmia recurrence. Major complications (cerebral, peripheral embolism or bleeding) occurred in 5 patients. Unilateral, thoracoscopic AF ablation is safe and technically feasible. However, the results of the microwave and monopolar radiofrequency devices were less than satisfactory, with a gradual decline in arrhythmia-free survival over a very long-term follow-up.

Electrophysiological findings after surgical thoracoscopic atrial fibrillation ablation

Hybrid ablation (a combination of thoracoscopic epicardial ablation and catheter ablation) has become a new technique for atrial fibrillation treatment. The goal of this study was to evaluate the success and electrophysiological follow-up after using the COBRA Fusion device to deliver a circumferential lesion set anterior to the pulmonary veins in an attempt to isolate the posterior left atrium (box isolation). Surgical ablation was carried out via a thoracoscopic approach using the COBRA Fusion radiofrequency catheter. An electrophysiology study was done 2-3 months later to verify box isolation (and to complete it, if needed) and to perform right-sided isthmus ablation. Fat thickness along the presumed box lesion line was measured using preprocedural computed tomography. Thirty patients (mean age 60.0 ± 11.6 years; 22 men; 8 with long-standing persistent AF and 22 with persistent atrial fibrillation) were enrolled. The duration of the EP study was 216.3 ± 64.2 minutes. Box isolation, based on the EP study, was complete in 12 patients (40%) and incomplete in 18 patients (60%). Successful box isolation was achieved with catheter ablation in 16 of 18 patients (89%). A total of 39 gaps in these 16 patients were identified. Typical gap locations were the anterior-superior part of the superior pulmonary veins and the roofline. Fat thickness along the roofline was substantially higher than that along the inferior line (4.58 ± 1.61 mm vs 2.37 ± 0.76 mm; P < .001). There is a relatively low rate of complete isolation using the COBRA catheter ablation system. The superior line and anterior parts of superior pulmonary veins have most conduction gaps.

Unanswered Question: Which Lesion Set Is Best in Thoracoscopic Atrial Fibrillation Ablation?

Objective: Pulmonary vein isolation (PVI) in minimally invasive atrial fibrillation (AF) ablation surgery is highly effective. Controversy exists, however, about the merit of extending the lesion set. The dilemma is not only the balance between increases of invasiveness versus potential therapeutic advantage. It is also our inability to truly map for gaps and non-transmurality of surgical or preexisting interventional ablation lines. We report the outcomes of our closed chest, beating heart AF ablation as the applied lesion set has evolved.

Surgical and hybrid atrial fibrillation ablation procedures

The purpose of this EP Wire is to survey clinical practice in this rapidly evolving field as the variety of surgical techniques and the heterogeneity of treated patients make the comparison of results and outcomes challenging. Twenty-four European centres, all members of the EHRA EP research network, responded to this survey and completed the questions. Of the participating centres, 11 (46%) performed (irrespective of the technique) stand-alone surgical atrial fibrillation (AF) ablation in 2011. Seven hospitals (64%) performed totally thoracoscopic AF ablation procedures off-pump (in 20-100% of their cases). The most commonly used lesion set was only pulmonary vein isolation in five hospitals (46%). Eight centres (73%) performed validation of the surgical lesion set at the time of intervention. The most important indication for performing stand-alone, totally thoracoscopic surgical AF ablation in seven participating hospitals was failed catheter ablation. According to their definition of success, participating centres reported their success rate to be 10-100% for paroxysmal AF and 0-95% for (longstanding) persistent AF. The most frequently encountered complications during stand-alone, surgical AF ablation were pneumothorax and haemothorax in up to 10% of the cases. This EP Wire survey shows a wide variation not only in indications for stand-alone, surgical AF ablation, but also in surgical techniques, lesion sets, follow-up, and outcome.

Wire perforation of Flex 10 microwave device during thoracoscopic atrial fibrillation ablation

Rapid advances in technology are increasing the repertoire of techniques available for the surgical treatment of atrial fibrillation (AF). These techniques utilize new devices which are normally safe. However, potential problems can arise with a new device as is illustrated in this report. A 58-year-old man underwent a thoracosopic AF ablation utilizing the Flex 10 probe (Guidant, Afix, Fremont, CA). We experienced an important device failure following thoracoscopic microwave AF ablation that has not been reported to date. Although new devices seem to be safe, potential problems often emerge with time, and clinicians pioneering these technologies have an obligation to report these experiences to the wider surgical community.