Hybrid Atrial Fibrillation Ablation Research Articles

The Effect of Atrial Fibrillation Ablation Techniques on P Wave Duration and P Wave Dispersion

A reduction in surface electrocardiogram (ECG) P wave duration and dispersion is associated with improved outcomes in atrial fibrillation ablation. We investigated the effects of different ablation strategies on P wave duration and dispersion, hypothesising that extensive left atrial (LA) ablation with left atrial posterior wall isolation would give a greater reduction in P wave duration than more limited ablation techniques. A retrospective analysis of ECGs from patients who have undergone atrial fibrillation (AF) ablation was performed and pre-procedural sinus rhythm ECGs were compared with the post procedure ECGs. Maximal P wave duration was measured in leads I or II, minimum P wave duration in any lead and values were calculated for P wave duration and dispersion. Left atrial dimensions and medications at the time of ECG were documented. Ablation strategies compared were; pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) and the persistent AF (PsAF) ablation strategies of pulmonary vein isolation plus additional linear lesions (Lines), left atrial posterior wall isolation via catheter (PWI) and left atrial posterior wall isolation via staged surgical and catheter ablation (Hybrid). Sixty-nine patients' ECGs were analysed: 19 PVI, 21 Lines, 14 PWI, 15 Hybrid. Little correlation was seen between pre-procedure left atrial size and P wave duration (r=0.24) but LA size and P wave duration was larger in PsAF patients. A significant difference was seen in P wave reduction driven by Hybrid AF ablation (p<0.005) and Lines (<0.02). There was no difference amongst P wave dispersion between groups but the largest reduction was seen in the Hybrid ablation group. P wave duration increased with duration of continuous atrial fibrillation. Hybrid AF ablation significantly reduced P wave duration and dispersion compared to other ablation strategies including posterior wall isolation via catheter despite this being the same lesion set.

Hybrid Atrial Fibrillation Ablation: Current Status and a Look Ahead.

Treatment of atrial fibrillation (AF) has evolved significantly during the last 3 decades. Successful surgical AF ablation was developed by the pioneering work of Dr James Cox in 1987 resulting in the development of the Cox-maze (CM) procedure.1 Further experience and incorporation of ablation technology allowed subsequent modifications to increase efficacy and decrease morbidity, resulting in the latest iteration—the CM IV.2 Despite the excellent results of open SA of AF, its widespread use has been limited by its morbidity, especially for stand-alone surgical procedures. Ablation lines from alternate energy sources to replace many of the surgical incisions in the cut and sew maze led to a thoracoscopic, minimally invasive, off-pump beating heart approach.1 Minimally invasive thoracoscopic surgery may improve on the results of AF catheter ablation but may not be as effective as open surgery because of limitations in creating transmural lesions in roof and floor of the left atrial posterior wall in some patients.3 In 1998, the observation by Haissaguerre et al2 that the pulmonary veins (PVs) serve as common sources of AF triggers in patients with paroxysmal AF paved the way for catheter AF ablation (CA) using radiofrequency energy. Although CA is associated with relatively low morbidity, it has been characterized by higher AF recurrence rates, especially in persistent and long-standing persistent AF.4 Because thoracoscopic SA and CA interventions may lead to incomplete isolation of the PVs and the posterior wall of left atrium, a hybrid option combining these 2 techniques was developed. The so-called hybrid strategies proposed to increase procedural success. In fact, single-center studies have demonstrated that catheter ablation may be effective in completing some of the lines created by the thoracoscopic-based SA procedure.5 Hybrid AF ablations in various centers have been variable in terms of surgical approach (thorascopic …

Midterm outcomes of two-staged hybrid ablation of persistent and long-standing persistent atrial fibrillation using the versapolar epicardial surgical device and subsequent catheter ablation.

Hybrid ablation of atrial fibrillation (AF) is a promising treatment strategy for patients with non-paroxysmal AF, although, data regarding mid-term outcomes are limited. Patients with persistent or long-standing persistent AF were enrolled. Initially, a thoracoscopic, right-sided, epicardial ablation was performed, with a goal of creating a box lesion on the posterior wall of the left atrium; a novel versapolar radiofrequency (RF) catheter was used. In patients enrolled later, occlusion of the left atrial appendage was also performed. An endocardial procedure was performed 2-4months later, with the goal of confirming/completing the box lesion and ablating the ganglionated plexi and cavotricuspid isthmus. Efficacy was assessed using multiple 24-h and 1-week Holter monitoring. Analysis was performed to search for variables associated with procedure's failure. Forty-one patients (14 persistent and 27 long-standing persistent AF) were enrolled with a mean AF duration of 33.5±33.1months. Mean follow-up was 507.2±201.1days (180-731). At the last follow-up visit, 27(65%) patients were arrhythmia-free, without anti-arrhythmics or need for re-ablation. Additional 4 patients (9.8%) were in sinus rhythm (SR) following re-ablation of postprocedural peri-mitral flutter and 4 (9.8%) were in SR on anti-arrhythmics. Longer periods of preoperative AF were independently associated with worse arrhythmia-free survival (p=0.015). Serious postoperative complications occurred in 3 (7.3%) patients; only 1 (2.4%) patient had clinical consequences after 6months. Hybrid ablation of non-paroxysmal AF using a novel, versapolar RF device yields promising mid-term results. Better arrhythmia-free survival rates were found in AF patients with shorter AF duration.

Two-staged hybrid ablation of non-paroxysmal atrial fibrillation: clinical outcomes and functional improvements after 1 year.

Hybrid ablation of atrial fibrillation (AF) is a promising treatment strategy; however, data regarding its efficacy and safety are still limited. Patients with non-paroxysmal AF were enrolled. First, a thoracoscopic, epicardial isolation of pulmonary veins and the left atrial posterior wall ('box lesion') was performed; a novel unipolar/bipolar radiofrequency device was used. Moreover, in 12 patients enrolled thereafter, the left atrial appendage was occluded. Electrophysiological evaluation and catheter ablation were performed 2-3 months later, with the goal of verifying or completing (if needed) the box lesion and ablation of the ganglionated plexi and the cavotricuspid isthmus. Outcomes were assessed using 1-week and 24-h Holter monitoring, repeated echocardiography and laboratory measurements. Thirty-eight patients (13 persistent and 25 long-standing persistent AF) were enrolled with a mean AF duration of 33 ± 32.9 months. The procedure was successfully completed in 35 patients; 3 patients underwent only the surgical part because of a postoperative left atrial appendage thrombus (2 patients) and perioperative stroke (1 patient). After 6 months, 30 (86%) patients were arrhythmia-free, whereas 80% were also off antiarrhythmics. After 1 year, 28 (82%) patients were arrhythmia-free, 79% were off anti-arrhythmics and 47% were off anticoagulation treatment. Four (10.5%) serious postoperative complications occurred, including 1 stroke, 1 right phrenic nerve palsy and 2 pneumothoraxes with a need for drainage. Significant improvements were observed in echocardiographic, functional and serological parameters. Hybrid ablation is an effective treatment strategy for patients with persistent or long-standing persistent AF. Over 80% of patients were arrhythmia-free 1 year after the procedure. Sinus rhythm restoration was accompanied by improvements in functional, echocardiographic and serological markers.

Middle-term results of hybrid atrial fibrillation ablation using AtriCure system

IntroductionLong-term results of catheter ablation (CA) for persistent and long-standing persistent atrial fibrillation (AF) are disappointing. The hybrid approach is currently one of options for overcoming the limitations of CA. AimTo evaluate the safety and medium-term efficacy of the hybrid approach in patients with persistent and long-standing persistent AF. MethodsAll patients underwent epicardial thoracoscopic radiofrequency (RF) pulmonary vein (PV) isolation using the AtriCure clamp followed by left atrial (LA) linear lesions (using a linear pen), Marshall ligament disruption, and LA appendage exclusion using an Atriclip. All patients underwent an electrophysiological study (EPS) and RF CA 2–3 months after the initial surgery to eliminate recurrent conductions from/to the PVs or across the linear lesions, and to eliminate all spontaneous and inducible atrial arrhythmias. 7-Day ECG Holter monitoring was performed every 3 months during the first year and every 6 months afterwards to evaluate possible recurrent arrhythmias. ResultsSeventy patients (49 male, median 63.5 years) took part in the study. EPS was performed 87 days (median) after the thoracoscopic surgery. Seventy-six percent of patients were in normal sinus rhythm (SR) at the start of the EPS, 7% had typical atrial flutter, 11% had atrial tachycardia, and 6% were in AF. After completion of the hybrid approach, all PVs were isolated, while a complete conduction block across the linear lines was achieved in 88.6% of patients. Twelve months after the procedure, 77.1% of patients had a stable SR without any anti-arrhythmic medication or re-ablation. If we included those on anti-arrhythmic drugs and re-ablation procedures, SR was achieved in 96.5% of patients during follow-up (936±432 days). ConclusionThe sequential hybrid approach is probably the most effective and relatively safe invasive treatment for persistent and long-term persistent AF with very low medium- to long-term recurrences. Introduction of the hybrid approach to clinical practice requires extensive cooperation between cardiologic and cardiothoracic teams.

Surgical and Hybrid Ablation of Atrial Fibrillation.

Atrial fibrillation (AF) is the most common arrhythmia in humans and is known to be associated with an increased risk of stroke, dementia, heart failure and mortality. Non-pharmacological therapy with ablation using either surgical or percutaneous techniques is recommended in drug refractory AF. Early attempts to devise procedures to ablate AF and restore sinus rhythm culminated with the Cox-Maze procedure, the first truly successful procedure. Since then, ablation surgery has been conducted predominately as a concomitant procedure. The Cox Maze procedure is complex and technically demanding and has, therefore, been extensively modified with new techniques for creating the linear ablation lines, new lesion sets, minimally invasive surgical techniques and most recently hybrid surgical-catheter ablation techniques. Surgical ablation techniques result in a marked reduction in atrial fibrillation when compared to conventional therapy with only a small increase in procedural risk. However, further research is required to more accurately quantify those benefits and to determine the optimal lesion sets, specific to the underlying arrhythmia mechanism and the optimal energy sources for ablation.

Adenosine administration during hybrid atrial fibrillation ablation to test dormant pulmonary vein conduction

BackgroundAdenosine administration after initial pulmonary vein isolation (PVI) reveals dormant conduction and predicts atrial fibrillation (AF) recurrence. Elimination of dormant conduction when present may increase a long-term success rate of AF ablation procedures. There are no studies till date using adenosine to reveal acute reconduction of pulmonary veins (PVs) after epicardial PVI during a hybrid AF ablation procedure.MethodsWe included 24 patients (21 male, 55 ± 9 years) undergoing hybrid ablation for symptomatic paroxysmal (n = 12) and persistent (n = 12) AF, using an epicardial bipolar radiofrequency clamp to perform PVI. All antiarrhythmic medications were discontinued 5 days prior to the procedure, except for patients on amiodarone. Thirty minutes after PVI and once sinus rhythm was obtained, a bolus of adenosine (12 to 36 mg) was administered intravenously. The subsequent response was assessed for each PV (n = 96) using an in situ circular mapping catheter.ResultsDormant conduction (i.e., the reappearance of PV potentials during at least one beat) was seen in 1 out of 96 PVs (1%). If reconduction was seen, further endocardial ablation using a 3.5-mm irrigated tip catheter was performed until no more reconduction occurred after repeating the adenosine bolus.ConclusionsAdenosine administration after PVI with the use of an epicardial bipolar radiofrequency clamp in the setting of hybrid AF ablation reveals acute reconduction in 1% of the PVs.

Hybrid ablation for atrial fibrillation: current approaches and future directions.

Catheter ablation of atrial fibrillation has rapidly evolved during the past decade: although the treatment of paroxysmal atrial fibrillation via a transcatheter approach has been consistently successful, persistent and long-standing atrial fibrillation still represents a major clinical challenge with less favorable outcomes to date. Because novel, minimally invasive surgical approaches have been developed for atrial fibrillation ablation, the aim of the present review is to analyze the current evidence surrounding the integration of surgical and transcatheter strategies in a hybrid fashion for the treatment of atrial fibrillation. Long-standing persistent, atrial fibrillation requires further understanding. Wide antral circumferential ablation of the pulmonary veins represents the cornerstone of any ablation therapy. Additional linear lesions and/or targeting complex fractionated atrial electrograms may also be considered. One of the limitations is achieving a transmural lesion. The combined endocardial and epicardial approach may represent a superior approach. Hybrid ablation of atrial fibrillation represents a novel therapeutic strategy for the treatment of complex scenarios, such as long-standing persistent atrial fibrillation. A specialized team including dedicated surgeons and cardiologists appears to be crucial in order to achieve durable and satisfactory outcomes following hybrid ablation of atrial fibrillation.

Minimally Invasive Epicardial Surgical Ablation Alone Versus Hybrid Ablation for Atrial Fibrillation: A Systematic Review and Meta-Analysis.

Maintaining sinus rhythm in patients with non-paroxysmal AF is an elusive goal. Some suggest that hybrid ablation, combining minimally invasive epicardial surgical ablation with endocardial catheter ablation, may be more effective than either modality alone. However, randomised trials are lacking. We investigated whether hybrid ablation is more effective than epicardial ablation alone at preventing recurrent AF by performing a systematic review and meta-analysis. The review was prospectively registered with PROSPERO (CRD42016043389). MEDLINE and EMBASE were searched for studies of standalone minimally invasive epicardial ablation of AF and/or hybrid ablation, identifying 41 non-overlapping studies comprising 2737 patients. A random-effects meta-analysis, meta-regression and sensitivity analysis were performed. Single-procedure survival free from atrial arrhythmias without antiarrhythmic drugs was similar between epicardial-alone and hybrid approaches at 12 months (epicardial alone 71.5 %; [95 % CI 66.1-76.9], hybrid 63.2 %; [95 % CI 51.5-75.0]) and 24 months (epicardial alone 68.5 %; [95 % CI 57.7-79.3], hybrid 57.0 %; [95 % CI 33.6-80.4]). Freedom from atrial arrhythmias with AADs and rates of unplanned additional catheter ablations were also similar between groups. Major complications occurred more often with hybrid ablation (epicardial alone 2.9 %; [95 % CI 1.9-3.9], hybrid 7.3 %; [95 % CI 4.2-10.5]). Meta-regression suggested that bipolar radiofrequency energy and thoracoscopic access were associated with greater efficacy, but adjusting for these factors did not unmask any difference between epicardial-alone and hybrid ablation. Hybrid and epicardial ablation alone appear to be equally effective treatments for AF, although hybrid ablation may be associated with higher complication rates. These data derived from observational studies should be verified with randomised data.

Hybrid ablation for atrial fibrillation: a systematic review.

PurposeHybrid 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).MethodsA systematic literature search was performed in the PubMed and Embase databases. All identified articles were screened and checked for eligibility by the two authors.ResultsTwelve 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).ConclusionThe 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.

96-14: Peri-atrial Fat Volume as a Predictor of Outcome in Hybrid Atrial Fibrillation Ablation

Introduction: Recently epicardial adipose tissue volume (EAT-V) has been linked to atrial fibrillation (AF) recurrence after catheter ablation. We have explored the relation between periatrial EAT-V and outcome after a hybrid AF ablation (simultaneous epicardial surgical and endocardial catheter ablation). Methods: Fifty patients, 26 paroxysmal (PAF), 22 persistent and 2 long-standing persistent AF (persAF), referred for a hybrid ablation were studied. On preoperative CT-scans, left atrial (LA) and right atrial (RA) EAT-V were quantified with custom-made software (imageJ). EAT was defined as any tissue located directly around the atria within a window of -30 to -190 Hounsfield Units. Also myocardial mass volumes (10 to 120 Hounsfield Units) and LA volumes (LAV) were assessed. Follow-up in 49 patients (1 lost to follow-up) at 1 year was according to the HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of AF. Results: Detailed results are depicted in the Table 1. EAT-V was not significantly different between PAF and persAF patients. EAT-V was not predictive of acute conduction block in the epicardial surgical box lesion. EAT-V neither was predictive of AF recurrence at 1 year. EAT-V in the RA was consistently higher compared to the LA, with significant differences in the PAF (P = 0.009) and persAF groups (P < 0.001). LA EAT-V correlated with LAV determined on CT (r = 0.42, P < 0.01), but not with LAV determined on echocardiography (r = 0.22, P = ns). Overall, LAV determined on CT correlated to but was systematically smaller than LAV determined on echocardiography (r = 0.40, P < 0.01). LA myocardial mass volume positively correlated with LA EAT-V (r = 0.42, P < 0.01). EAT-V = Epicardial Adipose Tissue, LA = Left Atrium, RA = Right Atrium, AF = Atrial Fibrillation, PAF = Paroxysmal AF, persAF = persistent + long-standing persistent AF, SR = Sinus Rhythm. EAT-V = Epicardial Adipose Tissue, LA = Left Atrium, RA = Right Atrium, AF = Atrial Fibrillation, PAF = Paroxysmal AF, persAF = persistent + long-standing persistent AF, SR = Sinus Rhythm. Conclusion: In patients undergoing hybrid AF ablation, total EAT-V is not predictive of recurrence at 1 year. However, LA EAT-V does increase with LAV. As such, fatty infiltration might play a role in early substrate development, and less in AF domestication. Furthermore, acute conduction block of the epicardial box lesion was not influenced by the total amount of left atrial fat.

The ABLA-BOX: An in Vitro Module of Hybrid Atrial Fibrillation Ablation

We present the first testing study on the ABLA-BOX, a new in vitro module of hybrid atrial fibrillation ablation. ABLA-BOX consists of two chambers that mimic the epicardial and endocardial sides of the heart. The septum between chambers provides catheter access on both sites of the cardiac tissue. A circuit, filled with freshly obtained porcine blood, including a pump, an oxygenator, and a heating device, circulate the blood inside the system. Left atrial fresh tissue is mounted on a tissue holder and magnetically fixed. Epicardial and endocardial catheters are fixed on the catheter holders and blocked with the locker knob. The system allows control of ablation force, flow rate, temperature, and flow pattern. Epicardial contact force of 100 g and endocardial force of 30 g resulted in larger lesion volumes (P < 0.001), areas (P < 0.001), and lesion diameters (P = 0.03 and P = 0.008), than the combination of 100/20 g. In addition, with a flow rate of 5 L/min, lesion volumes (P = 0.02), areas (P < 0.001), and diameters (both, P < 0.001) were significantly larger in comparison with those of 3 L/min. Furthermore, dimensions (both, P < 0.001), volume (P < 0.001), and area (P < 0.001) of the lesions at a circulating blood temperature of 38.0°C were larger than with a lower blood temperature (36.0°C). Finally, ablations made under stable flow pattern resulted in greater lesion diameters (P = 0.04 and P = 0.03) as well as larger volumes (P = 0.02) and areas (P = 0.03) than under turbulent-like flow reproduced with the system rotor set to 400 rpm. The ABLA-BOX allowed easy hybrid ablation with different setups, which can provide cardiologists and cardiac surgeons with reliable and more valuable insights.

Pulmonary vein triggers, focal sources, rotors and atrial cardiomyopathy: implications for the choice of the most effective ablation therapy.

Understanding of the pathophysiological mechanism(s) underlying atrial fibrillation (AF) is the foundation on which current ablation strategies are built. In the vast majority of patients with paroxysmal AF, the ablation procedure should target the pulmonary veins. In patients with nonparoxysmal AF, however, pulmonary vein isolation alone seems to be insufficient to prevent the arrhythmia. Several recent clinical trials have investigated the concept that rotors (re-entry based on a meandering central core from which spiral waves emanate) might be the mechanism responsible for sustaining AF. Ablation of these localized AF sources is an important step towards substrate-driven procedures in persistent AF. Hybrid AF ablation procedures, based on the integration of endocardial transcatheter and epicardial off-pump surgical techniques, have been introduced to overcome their mutual shortcomings. The long-term results are encouraging, especially in currently challenging settings such as nonparoxysmal AF and failed endocardial catheter ablation procedures.

Contact forces during hybrid atrial fibrillation ablation: an in vitro evaluation.

PurposeData on epicardial contact force efficacy in dual epicardial–endocardial atrial fibrillation ablation procedures are lacking. We present an in vitro study on the importance of epicardial and endocardial contact forces during this procedure.MethodsThe in vitro setup consists of two separate chambers, mimicking the endocardial and epicardial sides of the heart. A circuit, including a pump and a heat exchanger, circulates porcine blood through the endocardial chamber. A septum, with a cut out, allows the placement of a magnetically fixed tissue holder, securing porcine atrial tissue, in the middle of both chambers. Two trocars provide access to the epicardium and endocardium. Force transducers mounted on both catheter holders allow real-time contact force monitoring, while a railing system allows controlled contact force adjustment. We histologically assessed different combinations of epi-endocardial radiofrequency ablation contact forces using porcine atria, evaluating the ablation’s diameters, area, and volume.ResultsAn epicardial ablation with forces of 100 or 300 g, followed by an endocardial ablation with a force of 20 g did not achieve transmurality. Increasing endocardial forces to 30 and 40 g combined with an epicardial force ranging from 100 to 300 and 500 g led to transmurality with significant increases in lesion’s diameters, area, and volumes.ConclusionsIncreased endocardial contact forces led to larger ablation lesions regardless of standard epicardial pressure forces. In order to gain transmurality in a model of a combined epicardial–endocardial procedure, a minimal endocardial force of 30 g combined with an epicardial force of 100 g is necessary.

Repeat Procedures After Hybrid Thoracoscopic Ablation in the Setting of Longstanding Persistent Atrial Fibrillation: Electrophysiological Findings and 2-Year Clinical Outcome.

In order to increase success rates of invasive treatment of persistent atrial fibrillation, the hybrid approach was developed, combining video-assisted thoracoscopic epicardial procedure with conventional endocardial catheter ablation. Currently, there are no reports of electrophysiological findings and clinical outcomes of repeat procedures after the hybrid approach. Out of 64 patients who were treated by hybrid ablation for persistent atrial fibrillation (AF), 14 underwent the repeat catheter ablation and were selected for this study. All 14 patients initially presented with longstanding persistent atrial fibrillation and markedly dilated atria. The hybrid procedure was performed in a single act and the mean time to redo procedure was 346 ± 227 days. In 57% of patients indication for redo procedure was regular atrial tachycardia, and the rest presented with recurrent atrial fibrillation. In 36% of patients, recovered conduction was found along the previous ablation lesions. Only 9% of pulmonary veins were reconnected (0.36 veins per patient) and 7% of box lesions were not complete. The overall success rate at 2 years follow-up after the repeat procedure, including second repeat procedure and patients taking antiarrhythmic drugs, was 64% (57% without drugs and further ablation). One case of moderate pulmonary vein stenosis was detected as a consequence of hybrid procedure. Hybrid atrial fibrillation ablation results in durable lesions and high rates of chronic pulmonary vein isolation even after long-term follow-up. Most of the repeat procedures after the hybrid approach are related to left atrial flutters that could be successfully treated by catheter ablation.

The Late Electrophysiological Consequences Of Posterior Wall Isolation In Patients With Atrial Fibrillation.

There are many different lesion sets that are used for the surgical ablation of atrial fibrillation (AF). One such pattern is the 'box set', a single ring of scar delivered anterior to the pulmonary veins, which aims to electrically isolate the posterior wall from the rest of the heart. However it remains unclear whether posterior wall isolation (PWI) is an effective lesion set for maintenance of sinus rhythm and whether it is necessary to achieve complete bidirectional block. We investigated the long-term integrity of the 'box set' lesion created during surgical AF ablation by epicardial High Intensity Focussed Ultrasound (HIFU). All patients had documented persistent or recurrent paroxysmal AF prior to surgery. We correlated this with subsequent success or failure in the abolition of atrial fibrillation. With regional ethical and R&D approval, 101 patients who had previously undergone HIFU AF ablation greater than 4 years ago were screened for inclusion in the study. 17 patients agreed to late electrophysiological study: 11 with on-going AF and 6 in normal sinus rhythm. Clinical history and 7-day holters were used to define the NSR group. We performed a diagnostic EP study using a transseptal approach in fully anticoagulated patients (INR>2.0 and ACT maintained at >300s). A catheter was placed in the coronary sinus (CS) and a circular multipolar mapping catheter was used to map the left atrium and pulmonary veins. Patients in atrial fibrillation were cardioverted. We recorded whether posterior wall (PW) and pulmonary vein (PV) isolation had been achieved at the surgical procedure. In selected cases we recorded a voltage map using either CARTO (Biosense- Webster) or NavX (St Jude Medical) to identify areas of ablation scar. All 11 patients with AF had absence of PW+PV isolation with fractionated electrograms recorded across the PW. In the 6 patients with long-term freedom from AF, PW+PV isolation was confirmed in 4 (67%) and in 1 there was prolonged conduction across the box-set lesion with CS to PW activation time of around 200ms versus 45ms from mid-CS to left atrial appendage. Of the 4 patients with confirmed PW+PV isolation, 1 had dissociated spontaneous atrial potentials within the box set area and the other 3 had electrical silence throughout with inability to capture the posterior wall pacing at 10mA at multiple sites. There appears to be a clear correlation between the successful restoration of long-term sinus rhythm and isolation / delayed conduction from the pulmonary veins and posterior wall. Given the advent of hybrid atrial fibrillation ablation techniques designed to deliver this lesion set, these findings are timely and highly relevant.

Pericardial adhesions as a consequence of cryoballoon ablation detected during the hybrid AF ablation procedure

Pericardial adhesions as a consequence of cryoballoon ablation detected during the hybrid AF ablation procedure

Hybrid Treatment of Atrial Fibrillation

Endocardial catheter ablation (CA) and surgical Maze-like procedures have become mainstays of interventional treatment for atrial fibrillation (AF). However, CA has limited efficacy particularly in patients with persistent AF who have a high risk of recurrent AF. Epicardial CA in conjunction with endocardial CA, a hybrid CA, offers the potential advantage for robust lesion formation, left atrial debulking, and mapping and CA of residual arrhythmia circuits. Hybrid CA procedures may improve the success rate of an ablation procedure for AF, particularly in those with persistent or long-standing persistent AF and those with significant structural heart disease. However, the ideal patient populations who may benefit from hybrid AF ablation and the ideal tools and techniques for hybrid AF ablation have yet to be determined. In this review, we discuss the hybrid CA procedure including motivation for and methods of hybrid CA, available tools, and reported efficacy of the procedure.

The symbiosis of contact force catheter use for hybrid ablation for atrial fibrillation

ObjectiveReconduction across an ablation line is a common reason for arrhythmia recurrence over time. The hybrid procedure combines epicardial ablation of the pulmonary vein (PV) and creation of a box lesion with endocardial touch-ups for any electrical gaps. A high contact force (CF) between the ablation tip and cardiac tissue may increase the risk of thrombus formation, catheter tip charring, steam pop formation, and even cardiac perforation. CF monitoring is a significant new parameter for titration of the CF for creating an adequate lesion.MethodsThirty-eight consecutive patients underwent epicardial ablation using bipolar radiofrequency devices. After checking electrical bidirectional block of the ablation lines, an endocardial CF catheter was used for further ablation (if needed) to complete the isolation of PVs, box lesion, cavotricuspid isthmus (CTI), and complex fractionated atrial electrograms (CFAE).ResultsEndocardial touch-up was needed for 2 PVs (1.3 %) and 10 (26.3 %) box lesions. It was also used for the CTI line in 7 (18.4 %) patients, atrial tachycardia in 3 (7.9 %) patients, and additional CFAE ablation in 17 (44.7 %) patients. All 5 patients with arrhythmia recurrence had a mean CF < 10 g (p = 0.03). Procedure duration was significantly shorter in the CF group (223 ± 57 vs. 256 ± 60 min, p = 0.03) compared with control group.ConclusionUse of CF catheters is safe, feasible, and complementary to a hybrid procedure setup for atrial fibrillation ablation. Its real-time monitoring may predict future arrhythmia recurrence, and decrease procedure time.

25Invasive transseptal assessment of posterior wall isolation &gt;4yrs post surgical AF ablation in stable sinus rhythm and recurrent af patients. is isolation required for success?

Introduction: There are many different lesion sets that are used for the surgical ablation of atrial fibrillation (AF). One such pattern is the ‘box set’, a single ring of scar delivered anterior to the pulmonary veins, which aims to isolate the posterior wall from the rest of the heart. However it remains unclear whether posterior wall isolation (PWI) is required for maintenance of sinus rhythm. We investigated the long-term integrity of the ‘box set’ lesion created during surgical AF ablation by epicardial High Intensity Focussed Ultrasound (HIFU). All patients had documented persistent or recurrent paroxysmal AF prior to surgery. We correlated this with subsequent success or failure in the abolition of atrial fibrillation. Methods: With regional ethical and R&D approval, we recruited 16 patients, 10 with ongoing AF and 6 in normal sinus rhythm, who had previously undergone HIFU AF ablation: 14 during concomitant cardiac surgery and 2 stand alone ablation. Clinical history and 7-day holter was used to define the NSR group. We performed a diagnostic EP study using a transseptal approach in fully anticoagulated patients (INR > 2.0 and ACT maintained at >350s). A catheter was placed in the coronary sinus (CS) and a circular multipolar mapping catheter was used to map the left atrium and pulmonary veins. Patients in atrial fibrillation were cardioverted. We recorded whether posterior wall and pulmonary vein isolation (PWI + PVI) had been achieved at the surgical procedure. In selected cases we recorded a voltage map (EnSite™ Velocity™, St. Jude Medical, UK) to identify areas of ablation scar (see Figure 1). Results: All 10 patients with ongoing AF had absence of PWI + PVI with electrograms recorded across the PW. In the 6 patients with long-term confirmed sinus rhythm, PWI + PVI was confirmed in 4 (67%) and in 2 there was prolonged conduction across the box-set lesion with CS to PW activation time of around 200ms versus 45ms from CS to left atrial appendage. Of the 4 patients with confirmed PWI + PVI, 1 had dissociated spontaneous atrial potentials within the box set area and the other 3 had electrical silence with inability to capture the posterior wall pacing at 10mA at multiple sites Conclusions: There appears to be a clear correlation between the successful restoration of long-term sinus rhythm and isolation / delayed conduction from the pulmonary veins and posterior wall. Given the advent of hybrid atrial fibrillation ablation techniques designed to deliver this lesion set, these findings are of great significance. ![Graphic][1] Figure 1 Voltage map from EnSite™ Velovity™ with box-set lesion shown in red (arrow) [1]: /embed/inline-graphic-1.gif