Ablation of Persistent Atrial Fibrillation: Utilizing the Best of Both Worlds

In this article, the authors present a case study and overview of a new interdisciplinary approach to cardiac ablation of persistent atrial fibrillation.

Case Description

A 66-year-old male with a history of atrial fibrillation was referred for ablation for treatment of symptomatic persistent atrial fibrillation. The patient was diagnosed with atrial fibrillation six years ago and had previously failed treatment with amiodarone and sotalol. He was started on dofetilide and became paroxysmal, but continued to have symptomatic episodes of atrial fibrillation.

Two-dimensional echocardiogram revealed normal left ventricular function with an estimated ejection fraction of 55%. His left atrial diameter was 4.4 cm. He had no significant valvular heart disease.

The patient was scheduled for a co-disciplinary epicardial and endocardial radiofrequency ablation procedure, known as a convergent procedure, performed sequentially at the same sitting. It addresses patients with paroxysmal, persistent and longstanding persistent atrial fibrillation, those with large left atrial size, and those who have failed catheter ablation. It is a totally endoscopic trans-diaphragmatic approach to the epicardium without the need for chest incisions or lung deflations. It is followed by a conventional percutaneous endocardial ablation.

The procedure was performed under general anesthesia in the EP lab. Perioperative anticoagulation consisted of cessation of warfarin five days before the procedure and initiation of aspirin 325 mg daily. Transesophageal echocardiography was used to exclude LA thrombus. 

For the epicardial ablation, the patient's chest and abdomen were prepped and draped in a standard sterile fashion. A 5 mm Optiview trocar was then inserted in the left upper quadrant of the abdomen for laparoscopic exploration. CO2 pneumoperitoneum was created. An additional trocar (10/12 mm) was inserted in the subxyphoid region as well as an additional 5 mm trocar in the right upper quadrant. After general exploration of the abdomen, no abnormalities were identified. The central tendon of the right hemidiaphragm was identified. Just above the left lobe of the liver, a 1.5 cm incision was made in the central tendon of the diaphragm. Once the pericardium was identified, a 1.5 cm incision in the pericardium was created. An nContact cannula was then inserted under direct guidance through the diaphragm and pericardial incisions. A 7 mm scope was advanced through the cannula, and exploration of the pericardial sac was performed. The left inferior, left superior, right superior, right inferior pulmonary veins, and coronary sinus were identified. Using the Numeris® (nContact, Inc., Morrisville, NC) epicardial ablation catheter (Figure 1), radiofrequency ablation was performed starting from the coronary sinus to the left inferior pulmonary vein up toward the left superior pulmonary vein. The roof of the left atrium was crossed connecting the ablation from the left superior vein to the right superior pulmonary vein. The ablation was continued along the floor of the atrium adjacent to the right superior and inferior veins. This ablation line was brought as close to the oblique sinus as possible. Next, ablation was performed anterior to the left superior and inferior pulmonary veins using the Numeris® catheter off the wire. An additional ablation line connecting the left inferior pulmonary vein to the right inferior pulmonary vein was performed. Next, we crossed the inferior vena cava (IVC) and identified the superior vena cava (SVC), right superior and right inferior pulmonary veins. An ablation line was created under the SVC and followed along the pulmonary veins anteriorly on the right toward the oblique sinus (Figure 2). Once the ablation was completed, a BLAKE® drain (Ethicon, Inc., a Johnson & Johnson company, Somerville, NJ) was placed posteriorly in the pericardial sac. The BLAKE drain was brought out of the skin through the left upper abdominal port. The fascia was closed in the midline incision using interrupted Vicryl sutures. Subcutaneous tissues and skin were closed with serial Vicryl sutures. Total epicardial procedure time was 91 minutes. 

Following the epicardial ablation, the patient is prepped for conventional pulmonary vein antrum isolation. Two 8 French (Fr) sheaths were placed in the right femoral vein. An 11 Fr sheath and 8 Fr sheath were placed in the left femoral vein. A 10.5 Fr intracardiac echocardiographic catheter (ACUSON, Siemens) was advanced into the right atrium. This catheter was used to assist in the transseptal catheterization, to monitor for pericardial effusions and to identify the os of all 4 pulmonary veins. A deflectable decapolar catheter (Webster CS Bidirectional, Biosense Webster, Inc., a Johnson & Johnson company, Diamond Bar, CA) was advanced into the coronary sinus.

A circular mapping catheter (Lasso, Biosense Webster, Inc.) and a 3.5 mm tip irrigated radiofrequency (RF) ablation catheter (ThermoCool, Biosense Webster, Inc.) were passed through a Mullins sheath (Medtronic Inc., Minneapolis, MN) and SLO sheath, respectively, using a double transseptal catheterization. Intravenous heparin was administered to achieve activated clotting times of 300–350 seconds during the procedure.

Ablation was assisted with nonfluoroscopic electroanatomical mapping (Carto, Biosense Webster, Inc.). Since the patient had an epicardial ablation, pulmonary vein potentials were targeted first at the areas of pericardial reflections (Figure 2). The pulmonary vein potentials were assessed with the circular mapping catheter pre- and post-ablation. Maximal power was limited to 25 W on the posterior wall and 35 W elsewhere, and temperature was limited to 45 degrees.

Prior to the percutaneous endocardial ablation, there were pulmonary vein potentials seen around the left superior pulmonary vein (Figure 3), partially around the left inferior pulmonary vein (Figure 4), and around the right inferior pulmonary vein (Figure 5). The right superior pulmonary vein was completely isolated (Figure 6). All pulmonary veins were isolated individually. Endpoints were pulmonary vein potential and posterior wall potential abolition (Figures 7–9). Following complete isolation of all veins, burst pacing was performed down to 220 milliseconds, inducing atrial flutter. The atrial flutter appeared to be a typical right-sided atrial flutter with earliest activation in the proximal CS and a sawtooth pattern on the inferior leads. A cavotricuspid isthmus ablation was performed, resulting in termination of the atrial flutter. Trans-isthmus conduction times were 150 ms in both the clockwise and counterclockwise direction. Following this, burst pacing was performed a second time, inducing an atypical flutter which terminated after approximately two minutes and was not sustained on repeat induction. A biphasic external 30 J shock synchronized to the R wave was delivered as a further test for inducible AF,¹ which did not induce atrial fibrillation. The total endocardial procedure time was 126 minutes. Fluoroscopy time was 23 minutes. Total procedure time of the combined endocardial and epicardial ablation was 4 hours and 10 minutes.

After ablation, anticoagulation was reinitiated and dofetilide was continued for 8 weeks.

Following the procedure, the patient was transferred to the CICU overnight. Follow-up echo revealed a trivial pericardial effusion. The Blake drain was pulled on post-operative day 2. The patient was discharged home on post-operative day 4.

The patient did not have any symptomatic episodes of atrial fibrillation in the first 8 weeks post ablation. His dofetilide was discontinued, and he has remained free of any episodes of atrial fibrillation or atrial flutter. Holter monitor performed at 8 weeks did not reveal any episodes of atrial fibrillation. A 7-day event monitor performed at 6 months did not reveal any episodes of atrial fibrillation.

Challenges with Traditional Treatments

Although open-chest surgical procedures, such as the “cut and sew” Cox Maze, have been successful in the treatment of atrial fibrillation, they usually require cardiopulmonary bypass and have a higher rate of bleeding and need for permanent pacing.² The invasive nature of this type of procedure and the small number of surgeons who perform them have also limited its use. Minimally invasive surgical ablation procedures, such as the “mini-Maze,” which uses epicardial bipolar radiofrequency energy to isolate the pulmonary veins, have not resulted in the success rates of open-chest procedures.³ The mini-Maze procedure can also be proarrhythmic by promoting macro-reentrant circuits,⁴ is not truly minimally invasive because it requires chest incisions and lung deflations. These factors have resulted in limited widespread acceptance.

Percutaneous pulmonary vein antrum isolation has also been challenging for electrophysiologists and has not been demonstrated to result in the efficacy that has been seen in the Cox Maze for patients with persistent and permanent atrial fibrillation.^5,6

Interdisciplinary Solution

Much debate has been made between cardiothoracic surgeons and electrophysiologists regarding the best way to treat our patients who have drug resistant atrial fibrillation. The convergent procedure ends the debate by combining the best of both disciplines using a truly minimally invasive treatment solution in a single procedure. The cardiothoracic surgeon can isolate the pulmonary veins, except for the areas protected by the pericardial reflections. Since they are directly visualizing the lesions, it allows them to ensure the lesions are connected into a complete, comprehensive pattern. This technique also directs RF energy away from the esophagus during posterior wall ablation and results in significant debulking of the posterior wall. The electrophysiologist can then complete the pulmonary vein isolation and provide diagnostic confirmation that all veins are isolated, verify reentrant circuits have been blocked, and confirm posterior left atrial wall silence. If needed, they can also perform a mitral valve annulus ablation, tricuspid valve annulus ablation or coronary sinus ablation.

This new hybrid surgical/epicardial and electrophysiologic/endocardial approach to treating all types of AF patients, including longstanding persistent and persistent AF, offers high early success rates.^7,8 It reduces electrophysiologist procedural times (~1.5 hours) with reduced patient and physician fluoroscopy exposure (~10–30 min), as compared with historical and same institution catheter ablation data.⁹

We believe the convergent experience, which combines surgical and electrophysiological expertise, provides encouraging results in achieving freedom from atrial fibrillation. Further studies are enrolling to quantify the efficacy and safety of this procedure.^10,11

References

1. Wylie JV Jr, Essebag V, Reynolds MR, Josephson ME. Inducibility of atrial fibrillation with a synchronized external low energy shock post-pulmonary vein isolation predicts recurrent atrial fibrillation. J Cardiovasc Electrophysiol 2009;20:29-36.
2. Prasad SM, Maniar HS, Camillo CJ, et al. The Cox maze III procedure for atrial fibrillation: Long-term efficacy in patients undergoing lone versus concomitant procedures. J Thorac Cardiovasc Surg 2003;126:1822-1828.
3. Han FT, Kasirajan V, Kowalski M, et al. Results of a minimally invasive surgical pulmonary vein isolation and ganglionic plexi ablation for atrial fibrillation: Single-center experience with 12-month follow-up. Circ Arrhythm Electrophysiol 2009;2:370–377. 
4. Kron J, Kasirajan V, Wood MA, et al. Management of recurrent atrial arrhythmias after minimally invasive surgical pulmonary vein isolation and ganglionic plexi ablation for atrial fibrillation. Heart Rhythm 2010;7:445–451.
5. Bhargava M, Di Biase L, Mohanty P, et al. Impact of type of atrial fibrillation and repeat catheter ablation on long-term freedom from atrial fibrillation: Results from a multicenter study. Heart Rhythm 2009;6:1403–1412.
6. Elayi CS, Verma A, Di Biase L, et al. Ablation for longstanding permanent atrial fibrillation: Results from a randomized study comparing three different strategies. Heart Rhythm 2008;5:1658–1664. 
7. Gersak B. Single port subxyphoid approach for surgical ablation: Convergent procedure. European Association for Cardio-Thoracic Surgeons (EACTS). September 2010. 
8. Di Biase L, Bailey S, Kiser A, et al. Long-term results of the convergent endo-epicardial ablation procedure for the treatment of long standing persistent atrial fibrillation. Heart Rhythm Society. May 2010. 
9. Landers M, Kiser A, Boyce K, et al. Convergent procedure for persistent atrial fibrillation decreases fluoroscopy and procedure times. Heart Rhythm Society. May 2010. 
10. Safety and efficacy study of the combined ablation procedure to treat paroxysmal atrial fibrillation (CAP STOPS AF). Available at: https://clinicaltrials.gov/ct2/show/NCT01103674?term=atrial+fibrillation+ablation&lead=ncontact&rank=2
11. Safety and efficacy study of the combined ablation procedure to treat long-standing persistent atrial fibrillation (CAPstopsLSPAF). Available at: https://clinicaltrials.gov/ct2/show/NCT01103661?term=atrial+fibrillation+ablation&lead=ncontact&rank=1

Conflict of interest: Dr. Civello and Dr. Boedefeld report having an educational consulting agreement with nContact, Inc.

Editor’s Note: This article underwent peer review by one or more members of EP Lab Digest’s editorial board.