Linear left atrial lesions in minimally invasive surgical ablation of persistent atrial fibrillation: Techniques for assessing conduction block across surgical lesions

Hybrid Totally Thoracoscopic Maze and Catheter Ablation for Persistent Atrial Fibrillation: Initial Experience

Atrial fibrillation is now a pandemic in our ageing community. Although James L. Cox devised a surgical procedure with near-universal curative success in 1987, catheter-based interventions have flourished. For persistent atrial fibrillation (AF), however, an isolated endocardial approach has limitations: procedural times are long, carry risk, and the outcomes are not durable. By combining left atrial endocardial and epicardial interventions with staged mapping, we optimise the benefits of both approaches. Our initial series of hybrid ablation for persistent atrial fibrillation reports excellent early outcomes, freedom from complications and excellent success at follow-up.

The Minimum Number of Ablation Lines for Complete Isolation of the Pulmonary Veins during Thoracoscopic Ablation for Atrial Fibrillation

Total thoracoscopic ablation has been recommended as a class IIa indication for atrial fibrillation. However, the optimal number of ablation lines for pulmonary vein isolation has not yet been proposed. This study aimed to report the minimum number of ablation lines required to achieve an intraoperative conduction block. This study included a total of 20 patients who underwent total thoracoscopic ablation from December 2020 to July 2021. The epicardial conduction block was checked after each ablation line of pulmonary vein antral clamping. The median age was 61 years old. The median duration of atrial fibrillation since the first diagnosis was 78 months. Pulmonary vein isolation with bidirectional conduction block was confirmed in 90% of patients. A median of six ablation lines around each pulmonary vein antrum were performed according to our protocol even after the conduction block was verified. The median number of ablations to achieve an exit block was two on the right side and 3.5 on the left side. We found that most conduction blocks were achieved within three ablations around the pulmonary vein antrum. Our results may provide evidence to reduce the number of unnecessary ablation lines in the future.

Hybrid Ablation Versus Repeated Catheter Ablation in Persistent Atrial Fibrillation: A Randomized Controlled Trial

BACKGROUND

Although catheter ablation (CA) is successful for the treatment of paroxysmal atrial fibrillation (AF), results are less satisfactory in persistent AF. Hybrid ablation (HA) results in better outcomes in patients with persistent atrial fibrillation (persAF), as it combines a thoracoscopic epicardial and transvenous endocardial approach in a single procedure.

OBJECTIVES

The purpose of this study was to compare the effectiveness and safety of HA with CA in a prospective, superiority, unblinded, randomized controlled trial.

METHODS

Forty-one ablation-naive patients with (long-standing)-persAF were randomized to HA (n = 19) or CA (n = 22) and received pulmonary vein isolation, posterior left atrial wall isolation and, if needed, a cavotricuspid isthmus ablation. The primary efficacy endpoint was freedom from any atrial tachyarrhythmia >5 minutes off antiarrhythmic drugs after 12 months. The primary and secondary safety endpoints included major and minor complications and the total number of serious adverse events.

RESULTS

After 12 months, the freedom of atrial tachyarrhythmias off antiarrhythmic drugs was higher in the HA group compared with the CA group (89% vs 41%, P = 0.002). There was 1 pericarditis requiring pericardiocentesis and 1 femoral arteriovenous-fistula in the HA group. In the CA arm, 1 bleeding from the femoral artery occurred. There were no deaths, strokes, need for pacemaker implantation, or conversions to sternotomy, and the number of (serious) adverse events was comparable between groups (21% vs 14%, P = 0.685).

CONCLUSIONS

Hybrid AF ablation is an efficacious and safe procedure and results in better outcomes than catheter ablation for the treatment of patients with persistent AF. (Hybrid Versus Catheter Ablation in Persistent AF [HARTCAP-AF]; NCT02441738).

Five-year follow-up report: Box lesion radiofrequency ablation procedure for atrial fibrillation under video-assisted thoracoscope

We report the initial 5-year follow-up of a novel mini-invasive procedure for epicardial ablation for the treatment of atrial fibrillation. The initial 5-year survival rate is acceptable and comparable with that of hybrid ablation. And this shared procedure has the advantages of shorter operation time and less surgical trauma.

Ganglionated Plexi Ablation for the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common type of cardiac arrhythmia and is associated with significant morbidity and mortality. The autonomic nervous system (ANS) plays an important role in the initiation and development of AF, causing alterations in atrial structure and electrophysiological defects. The intrinsic ANS of the heart consists of multiple ganglionated plexi (GP), commonly nestled in epicardial fat pads. These GPs contain both parasympathetic and sympathetic afferent and efferent neuronal circuits that control the electrophysiological properties of the myocardium. Pulmonary vein isolation and other cardiac catheter ablation targets including GP ablation can disrupt the fibers connecting GPs or directly damage the GPs, mediating the benefits of the ablation procedure. Ablation of GPs has been evaluated over the past decade as an adjunctive procedure for the treatment of patients suffering from AF. The success rate of GP ablation is strongly associated with specific ablation sites, surgical techniques, localization techniques, method of access and the incorporation of additional interventions. In this review, we present the current data on the clinical utility of GP ablation and its significance in AF elimination and the restoration of normal sinus rhythm in humans.

Left atrial effective conducting size predicts atrial fibrillation vulnerability in persistent but not paroxysmal atrial fibrillation

Background

The multiple wavelets and functional re‐entry hypotheses are mechanistic theories to explain atrial fibrillation (AF). If valid, a chamber's ability to support AF should depend upon the left atrial size, conduction velocity (CV), and refractoriness. Measurement of these parameters could provide a new therapeutic target for AF. We investigated the relationship between left atrial effective conducting size (LA_ECS), a function of area, CV and refractoriness, and AF vulnerability in patients undergoing AF ablation.

Methods and Results

Activation mapping was performed in patients with paroxysmal (n = 21) and persistent AF (n = 18) undergoing pulmonary vein isolation. Parameters used for calculating LA_ECS were: (a) left atrial body area (A); (b) effective refractory period (ERP); and (c) total activation time (T). Global CV was estimated as √A/T. Effective atrial conducting size was calculated as LAECS=A/(CV×ERP). Post ablation, AF inducibility testing was performed. The critical LA_ECS required for multiple wavelet termination was determined from computational modeling. LA_ECS was greater in patients with persistent vs paroxysmal AF (4.4 ± 2.0 cm vs 3.2 ± 1.4 cm; P = .049). AF was inducible in 14/39 patients. LA_ECS was greater in AF‐inducible patients (4.4 ± 1.8 cm vs 3.3 ± 1.7 cm; P = .035, respectively). The difference in LA_ECS between inducible and noninducible patients was significant in patients with persistent (P = .0046) but not paroxysmal AF (P = .6359). Computational modeling confirmed that LA_ECS > 4 cm was required for continuation of AF.

Conclusions

LA_ECS measured post ablation was associated with AF inducibility in patients with persistent, but not paroxysmal AF. These data support a role for this method in electrical substrate assessment in AF patients.

Staged hybrid procedure versus radiofrequency catheter ablation in the treatment of atrial fibrillation

The treatment effect of the hybrid procedure, consisting of a thoracoscopic ablation followed by an endocardial radiofrequency catheter ablation (RFCA), is unclear. A total of 117 ablation-naïve patients who underwent either the staged hybrid procedure (n = 72) or RFCA alone (n = 105) for drug-refractory, non-valvular persistent or long-standing persistent atrial fibrillation (AF) were enrolled. The primary outcome is occurrence of total atrial arrhythmia, defined as a composite of AF, sustained atrial tachycardia (AT), and atypical atrial flutter (AFL) after index procedure. The mean age was 52.7 years. Eighty-four percentage of the patients were male. Patients with prior history of stroke and long-standing persistent AF were more prevalent in the hybrid group than RFCA group. The left atrial volume index was larger in the hybrid group (P<0.001). During 2.1 years of median follow-up, the incidence of total atrial arrhythmia was not different between the two groups (32.5% vs. 35.7%; adjusted hazard ratio: 0.64; 95% confidence interval: 0.36–1.14; P = 0.13). The AF recurrence was significantly lower in the hybrid group than in the RFCA group (29.6% vs. 34.9%; adjusted HR: 0.53; 95% CI: 0.29–0.99; P = 0.046). The hospital stay was longer in the hybrid group than in the RFCA group (11 days vs. 4 days; P<0.001). A staged hybrid procedure may be an alternative choice for drug-refractory persistent AF, but it is no more effective than RFCA alone to eliminate atrial arrhythmias. Considering the long-length of stay and the morbidity, careful consideration should be given in selection of treatment strategy.

Surgical Ablation of Atrial Fibrillation: is Electrical Isolation of the Pulmonary Veins a Must?

Ablation of atrial fibrillation (AF) is a well-established treatment option for patients with symptomatic AF refractory to antiarrhythmic drugs. The cornerstone of catheter ablation is electrical isolation of the pulmonary veins, since the pulmonary veins are the most common location for triggers of AF. Electrical reconnection of the pulmonary veins is associated with arrhythmia recurrence and therefore diminishes long-term success of catheter ablation of AF. Therefore, durable pulmonary vein isolation remains a condition sine qua non for catheter ablation of AF. The Cox-Maze procedure is considered an effective surgical cure of AF, however it has never been widely adopted due to its procedural complexity. Since the development of minimal invasive techniques for surgical AF treatment, surgical ablation of AF has regained interest. Most of the minimal invasive surgical AF ablations performed around the globe include pulmonary vein isolation as a part of the procedure. In this review, we explore the necessity of electrical isolation of the pulmonary veins in surgical AF ablation.

Hybrid ablation for atrial fibrillation: a systematic review

PURPOSE

Hybrid ablation for AF is performed in a growing number of centers. Due to absence of guidelines, operative approaches and perioperative care differ per center. In this review, an overview of findings from published studies on hybrid ablations is given, and related topics are discussed (e.g., one- and two-stage approaches, lesion sets, and patient management).

METHODS

A systematic literature search was performed in the PubMed and Embase databases. All identified articles were screened and checked for eligibility by the two authors.

RESULTS

Twelve studies describing a total of 563 patients were selected. Due to substantial differences in approaches (one-stage, two-stage, sequential), surgical techniques (bilateral or monolateral thoracoscopy, subxiphoideal, transabdominal), energy sources (unipolar, bipolar), lesion sets (applying left or right atrial lesions), periprocedural care and endpoints (monitoring, definition of recurrence), and success rates (sinus rhythm after a mean of 26 months) are difficult to compare and varied from 27 % (without antiarrhythmic drugs, AADs) to 94 % (with AADs). For studies using bipolar devices, success rates with the use of antiarrhythmic drugs were at least 71 %. Major complications such as bleeding, sternotomy, and death occurred in 7 % of the total population (of which ten complications, 16 %, occurred in the concomitant cardiac surgery hybrid group).

CONCLUSION

The field of AF ablation has dramatically changed over the past years, with one of the most recent developments the hybrid AF ablation. Lack of matching data hinders drawing conclusions and creating guidelines. Early results however are encouraging. More data are awaiting and needed.

Electrophysiological Perspectives on Hybrid Ablation of Atrial Fibrillation

To overcome limitations of minimally invasive surgical ablation as a standalone procedure in eliminating atrial fibrillation (AF), hybrid approaches incorporating adjunctive endovascular catheter ablation have been proposed in recent years. The endovascular component targets residual conduction gaps and identifies additional electrophysiological targets with the goal of minimizing recurrent atrial arrhythmia. We performed a systematic review of published studies of hybrid AF ablation, analyzing 432 pooled patients (19% paroxysmal, 29% persistent, 52% long-standing persistent) treated using three different approaches: A. bilateral thoracoscopy with bipolar radiofrequency (RF) clamp-based approach; B. right thoracoscopic suction monopolar RF catheter-based approach; and C. subxiphoid posterior pericardioscopic ("convergent") approach. Freedom from recurrence off antiarrhythmic medications at 12 months was seen in 88.1% [133/151] for A, 73.4% [47/64] for B, and 59.3% [80/135] for C, with no significant difference between paroxysmal (76.9%) and persistent/long-standing persistent AF (73.4%). Death and major surgical complications were reported in 8.5% with A, 0% with B and 8.6% with C. A critical appraisal of hybrid ablation is presented, drawing from experiences and insights published over the years on catheter ablation of AF, with a discussion of the rationale underlying hybrid ablation, its strengths and limitations, where it may have a unique role in clinical management of patients with AF, which questions remain unanswered and areas for further investigation.

Study on Left Atrial Dimension and Function After Modified Endoscopic Procedure for Atrial Fibrillation at Two Years' Follow-Up

BACKGROUND

Modified endoscopic procedures for atrial fibrillation (AF) have a greater success rate because of the increased number of linear lesions. Concerns have been raised about the impact of ablation scars on the left atrium. This study aimed to examine the impact of ablation on left atrial dimension and systolic function after modified endoscopic procedures with echocardiographic measurement.

METHODS

Of 107 patients undergoing modified endoscopic ablation, 58 had paroxysmal AF and 49 had persistent or long-standing AF. The procedure was performed on the beating heart through three ports on the left chest wall. Three circular and two linear lesions were made on the left atrium. The left atrial appendage was excised by stapler. Echocardiography was performed preoperatively and at the 2-year follow-up.

RESULTS

Most patients (86.9%) patients were in sinus rhythm (SR) postoperatively. Fourteen patients (5 with paroxysmal AF and 9 with persistent/long-standing AF) failed to maintain SR. Echocardiographic data indicated that the left atrial diameter decreased only in the patients with postoperative SR but continued to increase in patients with fail SR maintenance. Left atrial function was also improved after the procedure, especially in patients with preoperative nonparoxysmal AF or with postoperative SR maintenance. Furthermore, left atrial function in patients who failed to restore SR was not worsened even with left atrial appendage excision.

CONCLUSIONS

Modified endoscopic procedure for AF improved post-procedural left atrial function of patients with SR maintenance. The left atrial function of patients with failed SR maintenance was also not worsened after left atrial appendage excision.

Surgical Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common chronic arrhythmia in the adult population. Ablation lines have largely replaced the historical and challenging cut and sew techniques. Surgical ablation of AF is commonly performed in cases with other indications for cardiac surgery and less commonly as a stand-alone therapy. Pulmonary vein isolation is the cornerstone of this procedure. Extended left atrial ablation lines may increase efficacy in cases with longstanding persistent or permanent AF. Additional efficacy by adding right atrial ablation is controversial but is often performed in cases undergoing right atrial or atrial septal surgery. Left atrial volume reduction is recommended in cases with large left atria and AF undergoing another cardiac surgery. Arrhythmia recurrence is not uncommon after surgical ablation of AF and varies among studies due to heterogeneity in patient population, lesion set and endpoints. Freedom from AF recurrence was 65-87% at 12 months and 58-70% at 2 years follow-up. Long-term monitoring is recommended due to an increased prevalence of asymptomatic recurrences. The strongest predictors of AF recurrence are longstanding or persistent AF and a large left atrium. The most common mechanisms of recurrence are pulmonary vein reconnection, nonpulmonary vein triggers, and gaps in the ablation lines. About 20% of atrial tachyarrhythmia recurrences are atrial flutter or atrial tachycardia. There are not enough data in the surgical literature to support withdrawal of anticoagulation after surgical AF ablation. Patients selected for stand-alone surgical ablation usually have low risk profiles and low postoperative mortality rates (0.2%).

Modern treatment of atrial fibrillation

Atrial fibrillation (AF) is the most common type of arrhythmia and has a large global burden. In general, treatment of AF is based on medication and consists of rate and rhythm control together with anticoagulation. However, surgical treatment may be required in patients with AF combined with organic valvular heart diseases or who experience recurrence despite medication. In addition, surgical treatment plays a role in the treatment of lone AF. This article reviews the various surgical treatment options for AF.

Hybrid therapy in the management of atrial fibrillation

Atrial fibrillation is the most common sustained arrhythmia. Because of the sub-optimal outcomes and associated risks of medical therapy as well as the recent advances in non-pharmacologic strategies, a multitude of combined (hybrid) algorithms have been introduced that improve efficacy of standalone therapies while maintaining a high safety profile. Antiarrhythmic administration enhances success rate of electrical cardioversion. Catheter ablation of antiarrhythmic drug-induced typical atrial flutter may prevent recurrent atrial fibrillation. Through simple ablation in the right atrium, suppression of atrial fibrillation may be achieved in patients with previously ineffective antiarrhythmic therapy. Efficacy of complex catheter ablation in the left atrium is improved with antiarrhythmic drugs. Catheter ablation followed by permanent pacemaker implantation is an effective and safe treatment option for selected patients. Additional strategies include pacing therapies such as atrial pacing with permanent pacemakers, preventive pacing algorithms, and/or implantable dual-chamber defibrillators are available. Modern hybrid strategies combining both epicardial and endocardial approaches in order to create a complex set of radiofrequency lesions in the left atrium have demonstrated a high rate of success and warrant further research. Hybrid therapy for atrial fibrillation reviews history of development of non-pharmacological treatment strategies and outlines avenues of ongoing research in this field.

Cardiac Autonomic Denervation for Ablation of Atrial Fibrillation

The influence of the autonomic nervous system (ANS) on triggering and perpetuation of atrial fibrillation (AF) is well established. Ganglionated plexi (GP) ablation achieves autonomic denervation by affecting both the parasympathetic and sympathetic components of the ANS. GP ablation can be accomplished endocardially or epicardially, i.e. during the maze procedure or thoracoscopic approaches. Recent evidence indicates that anatomic GP ablation at relevant atrial sites appears to be safe and improves the results of pulmonary vein isolation in patients with paroxysmal and persistent AF.

Hybrid surgical and catheter treatment for atrial fibrillation

Advances in surgery for atrial fibrillation from cut and sew technique to thoracoscopy and new energy source have enabled minimally invasive approach which avoids median sternotomy and cardiopulmonary bypass. However, minimally invasive approach is unable to match the outcome of classic surgical technique due to difficulty in creating some of linear ablation lines. Hybrid procedure using catheter mapping and ablation in addition to minimally invasive surgical ablation has gained interest to combine the advantages of both procedures. No large study has been conducted to date comparing this new technique to other existing treatments. The aim of this paper is to review the data on hybrid procedure for atrial fibrillation and assess its early outcome and efficacy.

Electrophysiological Evaluation of Thoracoscopic Pulmonary Vein Isolation

Although the majority of patients with atrial fibrillation and an indication for non-pharmacological therapy is treated with catheter ablation, thoracoscopic surgery is an emerging technique that aims at combining the results of the classic Cox Maze operation with a less invasive approach. Recurrences after thoracoscopic surgery have been mainly ascribed to incomplete ablation lines, but literature on electrophysiological confirmation of thoracoscopic pulmonary vein isolation is limited. Currently, surgical confirmation of uni- or bidirectional conduction block may be hampered by insufficient resolution of the mapping material available. Additionally uncertainty remains on the precise lesions sets required, and how to tailor them to individual patients. In hybrid procedures, electrophysiologists and surgeons join forces to combine their expertise and skills which may lead to increased procedural success rates by minimizing the chance of incomplete PV isolation or absence of conduction block across an alternative ablation line. Here we describe techniques for thoracoscopic mapping and present a literature review.

New technologies and hybrid surgery for atrial fibrillation

The Cox maze III and Cox maze IV procedures are surgical solutions for the treatment of symptomatic stand-alone atrial fibrillation. Despite their proven efficacy, these procedures have not gained widespread acceptance because of the invasiveness, complexity, and technical difficulty. Endocardial pulmonary vein isolation is the cornerstone of percutaneous catheter ablation for atrial fibrillation. It is currently accepted as an invasive therapy, if rhythm control has failed using antiarrhythmic drugs or electrical cardioversions. Pulmonary vein isolation is reported to be effective in 60%-85% of patients with paroxysmal atrial fibrillation and in 30%-50% of patients with persistent atrial fibrillation. A second or third ablation is often necessary to achieve these results, and complications may occur in up to 6% of patients. Surgical treatment of atrial fibrillation has seen important improvements in the last decade. New technologies have simplified creation of transmural lesions on the beating heart through a less-invasive, thoracoscopic procedure. This allows for pulmonary vein isolation, isolation of the posterior wall, and left atrial appendage exclusion-usually combined with ganglionic plexi evaluation and destruction. Nonetheless, it is still uncertain whether these procedures are effective in restoring permanent sinus rhythm since transmurality of a lesion set cannot be guaranteed with current ablation catheters on the beating heart. In an attempt to limit the shortcomings of an endo- or an epicardial technique, a hybrid approach has recently been introduced. This approach is based on a close collaboration between the surgeon and the electrophysiologist, employing a patient-tailored procedure which is adapted to the origin of the patient's atrial fibrillation and takes into consideration triggers and substrate. Using a mono- or bilateral energy source, a thoracoscopic epicardial approach is combined with a percutaneous endocardial ablation in a single-step or in a sequential-step procedure. This article provides our experience and an overview of the current knowledge in the hybrid treatment of stand-alone atrial fibrillation.

Double Potential Mapping: A Novel Technique for Locating the Site of Incomplete Ablation

Objective

Double potential mapping using bipolar electrodes that straddle the ablation line should identify the site of incomplete ablation as a conduction gap without constructing the activation maps.

Methods

Bipolar electrograms were recorded during pacing using 11 custom-made bipolar electrodes straddling the ablation line created by a bipolar radiofrequency ablation device on the lateral right atrium in seven canines. A linear ablation was made with an ablation device, of which one jaw was inserted into the atrium through a purse-string suture. A 3-mm-wide tape was placed on both jaws 10 mm from the tip of the ablation electrode to intentionally create an incomplete ablation lesion. The activation times at each dipole across the ablation line were defined as the times of the maximum positive and negative derivatives of the double potentials, and the site of conduction gap was determined as the site of the earliest activation across the linear ablation. The lateral right atrium was mapped simultaneously with 45 different bipolar electrodes to construct the activation maps and the earliest activation site across the ablation line was determined.

Results

The double potential mapping located the conduction gap on a real-time basis without displaying any maps. There was no significant change in the accuracy between the different times after ablation and different pacing cycle lengths.

Conclusions

Double potential mapping locates the conduction gap on a real-time basis and would be useful in beating-heart epicardial ablation in off-pump setting.

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.

A review of current surgical treatment of patients with atrial fibrillation

Surgical therapy for patients with atrial fibrillation has undergone significant advances over the past 30 years. The Cox Maze III technique is currently the gold standard of care for these patients. However, Maze IV, a less complex procedure using alternative energy sources, is rapidly replacing the Cox Maze III in clinical practice. The use of alternative energy sources such as cryothermy and radiofrequency eliminates some of the "cut and sew" lesions of the Maze III, resulting in an easier and faster procedure with less morbidity. Video-assisted technology and hybrid procedures have further ushered in the future of surgical therapy. This article presents the latest surgical therapeutic options for patients with atrial fibrillation. The history of these procedures is presented, followed by a discussion of modern-era techniques, including concomitant ablation and standalone (also referred to as "lone") procedures. Finally, the article explores breaking developments and future directions for the surgical treatment of patients with atrial fibrillation.