Collaborative Convergent Epicardial and Endocardial Atrial Fibrillation Ablation

Ayotunde M. Bamimore, MDa, J. Paul Mounsey, BM, BCh, PhDa, Andy C. Kiser, MDb

a Division of Cardiology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; b Division of Cardiothoracic Surgery, Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina

Ayotunde M. Bamimore, MDa, J. Paul Mounsey, BM, BCh, PhDa, Andy C. Kiser, MDb

a Division of Cardiology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; b Division of Cardiothoracic Surgery, Department of Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina

Background

Endocardial ablation in patients with longstanding persistent atrial fibrillation (AF) is associated with limited levels of success compared to patients with paroxysmal AF, especially in the presence of structural heart disease.1 More extensive ablation strategies such as collaborative convergent epicardial and endocardial radiofrequency ablation (RFA) results in a higher likelihood of terminating AF and maintaining sinus rhythm in such patients.2 In this issue of EP Lab Digest®, we describe a case utilizing this collaborative technique.

Case Presentation

A 63-year-old man with a five-year history of paroxysmal AF transitioned to persistent AF in the six months preceding consultation, resulting in worsening fatigue and shortness of breath.

He had a recent diagnosis of heart failure secondary to dilated cardiomyopathy with an ejection fraction (EF) of 30–35%, a left atrial size of 5.4 cm, and a 50% right coronary artery stenosis found on cardiac catheterization. His past medical history was significant for hypertension, obstructive sleep apnea, and a remote history of pulmonary embolism treated with an IVC filter as well as warfarin. His arrhythmia and the disabling symptoms of fatigue and shortness of breath were resistant to propafenone and chronic oral amiodarone therapy, so he was referred for an AF ablation. In view of the chronicity of his AF, his low EF, the degree of left atrial dilatation, and prior resistance to amiodarone, we recommended a convergent epicardial and endocardial AF ablation given the anticipated low likelihood of success with conventional endocardial ablation. He had a cardiothoracic surgical evaluation and was discussed at our multidisciplinary convergent AF ablation meeting, following which the AF coordinator along with the EP nurse practitioners proceeded to arrange an anesthesia consult for advanced planning. In addition, a CT scan of the left atrium was obtained to help create a 3D electroanatomic map, and a transesophageal echocardiogram was obtained to rule out the presence of thrombus. He had a loop recorder implanted (Reveal®, Medtronic) in the interim for long-term arrhythmia burden monitoring; this pre-operatively confirmed a 100% AF burden.

On the day of procedure, the patient was brought into the hybrid EP laboratory in a fasting state, and EKG leads, 3D electroanatomic mapping pads for EnSite NavX (St. Jude Medical), and indifferent electrodes for RFA were applied by the EP staff. In a supine position, general anesthesia was induced with a double lumen endotracheal tube, and a radial arterial line was established for hemodynamic monitoring. The operating room staff then stepped in to prep and drape the patient in a manner adopted to facilitate right transthoracic access for epicardial ablation as well as bilateral groin access for insertion of sheaths and catheters for endocardial ablation. A 5 cm right submammary incision was extended to the right fifth intercostal space. The right lung was deflated to expose the heart in the pericardial sac. The pericardium was opened anterior to the phrenic nerve, and the transverse and oblique sinuses were mobilized. A quadripolar diagnostic catheter was used to map the posterior wall of the left atrium as well as the pulmonary veins. An integrated unipolar and bipolar RFA device (Fusion, Estech) was then passed along the transverse sinus cephalad to the right and left superior pulmonary veins, and magnetic passers were used to curve the device downwards posterior to the left atrial appendage but anterior to the left-sided veins and then distal to the inferior pulmonary veins to come out from the oblique sinus. In so doing, the ablation device wrapped around the left atrium and was used to create a box lesion of ablation applying 50W per electrode, generating 70º C for 60 seconds for each ablation. The intention was to render the posterior wall as well as the pulmonary veins electrically silent. A box lesion was also made on the lateral surface of the right atrium (Figure 1), following which the device was removed and a posterior pleural drainage tube positioned. Following this, the electrophysiologist then started with the endocardial portion. Two transseptal accesses were obtained with the aid of an intracardiac echocardiogram (ICE catheter, Boston Scientific). Using a 3.5 mm tip roving ablation catheter (Chilli, Boston Scientific) as well as a Lasso catheter (Biosense Webster), we constructed a 3D electroanatomic map of the left atrium and pulmonary veins using the EnSite NavX mapping system. A voltage map of the left atrium revealed extensive areas of scar but with the presence of residual electrical signals within the left-sided veins, requiring minimal segmental ablation. Once completed, all four veins were documented as electrically isolated with entrance and exit blocks. RFA was in power-controlled mode with temperature limited by power set between 25W and 40W for 40 seconds. Supplemental lines of ablation were made on the roof to complete the connection of the left upper to the right upper pulmonary veins; a low posterior line was also made to connect the left inferior to the right inferior veins, and a mitral isthmus line was made to connect the left inferior to the annulus of the mitral valve. Of note, there was a temperature probe placed in the patient’s esophagus, and power was interrupted for every 0.4 C degree rise. Finally, we performed a line of ablation within the coronary sinus itself and then cardioverted the patient with 200 J DC energy after failing to convert to sinus rhythm with ibutilide. Once the patient was in sinus rhythm, we created a line of ablation along the cavotricuspid isthmus to achieve bidirectional isthmus conduction block. The post-operative period was challenged by the development of dysautonomia, as evidenced by significant bradycardia and hypotension, that was treated successfully with a dopamine infusion. The patient also had an episode of atypical flutter requiring cardioversion. He received a prophylactic dose of methylprednisone to pre-empt pericarditis. He was discharged on dofetilide on post-op day 7 and was seen in the cardiothoracic surgical clinic a week later. In the cardiology clinic six weeks later, he admitted marked improvement in energy and was still in sinus rhythm.

Discussion

Although percutaneous endocardial ablation may terminate longstanding persistent atrial fibrillation,3 the outcome is limited in patients with co-existing structural heart disease and dilated atria.1 On the other hand, the Cox III maze “cut and sew” procedure is very effective in this cohort, with success rates approaching 89% off antiarrhythmic agents and improving to 98% on medications.4 However, the Cox procedure requires open-heart surgery, with its attendant morbidity and mortality of 2–3%.5 Therefore, attempts have been made to develop procedures that combine the efficacy of a surgical procedure with the safety and limited morbidity of a percutaneous endocardial ablation. To this end, the convergent hybrid epicardial and endocardial ablation was developed.6 This procedure closely replicates the complex bi-atrial lesion sets of the Cox III maze procedure by a combination of: (a) RF lesions on the epicardial surface of a beating heart via a limited trans-thoracic or trans-abdominal approach, and (b) endocardial lesions to make the final lesion set contiguous and more effectively transmural. 

Notably, initial procedures developed to replicate the Cox III lesion sets in less invasive ways that would not require sternotomies or cardiopulmonary bypass created “epicardial-only” lesions. Given the fact that no current modality of ablation is able to create transmural lesions when applied to the epicardium, these initial procedures had limited success.6 With the convergent strategy, the addition of endocardial lesion sets improves on the shortcomings of “epicardial-only” minimally invasive procedures, even though these “epicardial-only” procedures have evolved over time to more closely resemble the Cox III lesions sets.7,8 Furthermore, the convergent procedure through its collaboration with electrophysiologists permits simultaneous sophisticated mapping to ensure the integrity of the epicardial lesions by confirming conduction block along the lines of RFA ablation. By using this strategy, Kiser et al6 demonstrated a 12-month sinus rhythm rate of 77% without antiarrhythmic drugs compared to 47% in patients with an extensive “epicardial-only” Ex-maze procedure; since then, the use of the strategy has expanded. The largest cohort to-date that underwent the convergent approach was reported by Gehi et al,2 when our institution demonstrated a 12-month sinus rhythm rate of 66% in spite of the fact that the cohort had persistent atrial fibrillation for an average duration of six years, a mean atrial size of 5.1 cm (largest 7 cm), and multiple comorbidities including sleep apnea and heart failure. Even more importantly, those patients who had recurrence of atrial fibrillation still experienced an improvement in their symptoms, which ultimately is what we are trying to achieve. This collaborative strategy of cardiac surgery and electrophysiology working together holds promise for the future.

In conclusion, the convergent atrial fibrillation ablation strategy is an effective method of treating longstanding persistent atrial fibrillation in patients with structural heart disease by creating robust, contiguous and transmural lesions that mimic the Cox III maze lesions via epicardial and endocardial ablations. 

Disclosure: Dr. Bamimore has no conflicts of interest to report. Dr. Mounsey reports consultancy with, honoraria from, and travel/accommodations expenses covered or reimbursed by Medtronic, Estech, St. Jude Medical, and Boston Scientific. Dr. Kiser reports consultancy and payment for development of educational presentations including service on speakers’ bureaus with Estech and KARL STORZ. 

References

  1. Matsuo S, Lellouche N, Wright M, et al. Clinical predictors of termination and clinical outcome of catheter ablation for persistent atrial fibrillation. J Am Coll Cardiol. 2009;54(9):788-795. 
  2. Gehi AK, Mounsey JP, Pursell I, et al. Hybrid epicardial-endocardial ablation using a pericardioscopic technique for the treatment of atrial fibrillation. Heart Rhythm. 2013;10(1):22-28. 
  3. Haïssaguerre M, Hocini M, Sanders P, et al. Catheter ablation of long-lasting persistent atrial fibrillation: clinical outcome and mechanisms of subsequent arrhythmias. J Cardiovasc Electrophysiol. 2005;16(11):1138-1147. 
  4. Cox JL, Boineau JP, Schuessler RB, Kater KM, Lappas DG. Five-year experience with the maze procedure for atrial fibrillation. Ann Thorac Surg. 1993;56(4):814-823; discussion 823-824. 
  5. Cox JL, Ad N, Palazzo T, et al. Current status of the Maze procedure for the treatment of atrial fibrillation. Semin Thorac Cardiovasc Surg. 2000;12(1):15-19.
  6. Kiser AC, Landers MD, Boyce K, Sinkovec M, Pernat A, Geršak B. Simultaneous catheter and epicardial ablations enable a comprehensive atrial fibrillation procedure. Innovations (Phila). 2011;6(4):243-247. 
  7. Mack MJ. Current results of minimally invasive surgical ablation for isolated atrial fibrillation. Heart Rhythm. 2009;6(12 Suppl):S46-49.
  8. Edgerton JR, Edgerton ZJ, Weaver T, et al. Minimally invasive pulmonary vein isolation and partial autonomic denervation for surgical treatment of atrial fibrillation. Ann Thorac Surg. 2008;86:35–38.