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How To Do It

Totally Extracardiac Maze Procedure Performed on the Beating Heart

^a Division of Cardiothoracic Surgery, Pinehurst Surgical Clinics, Pinehurst, North Carolina
^b Klinikum der Johann Wolfgang Goethe-Universitat, Frankfurt, Germany
^c Brody School of Medicine at East Carolina University, Greenville, North Carolina

Accepted for publication August 14, 2007.

^_* Address correspondence to Dr Kiser, Pinehurst Surgical Clinics, Cardiac and Thoracic Surgery, 5 FirstVillage Dr, Pinehurst, NC 28374 (Email: akiser{at}pinehurstsurgical.com).

Drs Kiser and Wimmer-Greinecker disclose that they have a financial relationship with nContact Surgical Inc.

 

	Abstract

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The cut-and-sew Cox Maze III procedure is a complex operation. A novel vacuum-integrated radiofrequency ablation device was developed to attenuate the complexity. This device has enabled the development of a totally extracardiac Maze (Ex-Maze) procedure. We describe the Ex-Maze procedure, which closely mimics the gold standard Maze III pattern and includes lines of ablation that isolate the pulmonary veins, interconnect the left and right atria, and a line that extends from the right inferior pulmonary vein to the medial inferior vena cava.

Despite innovations, a complete Cox Maze III procedure cannot be performed on the beating heart. Less complex Maze-like procedures generally limit treatment to the left atrium alone. However, the best surgical treatment for atrial fibrillation is the complete, biatrial Maze III lesion pattern [1, 2]. A novel radiofrequency ablation device (nContact Surgical Inc, Morrisville, NC) can create transmural ablative lesions in any pattern on a beating heart. We describe an ablation pattern, performed totally on the epicardium, which closely imitates the gold standard Maze III procedure (Fig 1).

View larger version (74K): [in this window] [in a new window]   Fig 1. Illustration of the extracardiac Maze lesion pattern. Numbers designate ablation lines.

	Technique

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Device Description
The ablation device uses unipolar radiofrequency energy with vacuum-maintained contact and suction-controlled saline perfusion to ensure uniform energy transmission and transmural lesion development. The average energy delivered is 50 W for 90 seconds. Suction encourages the electrode coil into approximation with the epicardial surface, thus ensuring consistent contact. The flexible low-profile device conforms to the anatomic surface of the heart. The device can be manipulated manually or guided with a tether. The ablation lesions are clearly visible on the myocardium, allowing the surgeon to create continuous lesion patterns on the epicardium (Fig 2).

View larger version (115K): [in this window] [in a new window]   Fig 2. Operative photo of the right atrium and right pulmonary veins demonstrates the extracardiac-Maze ablation lines 5 and 8. (PV = pulmonary vein; SVC = superior vena cava.)

Lesion 1 (Fig 3) is created by positioning the device toward, but not onto, the coronary sinus. Epicardial contact is verified by the audible "seal" of suction with the epicardium and by verifying saline perfusion through the device. The device is withdrawn behind the left pulmonary veins to create lesion 2. Lesion continuity is visually verified to avoid gaps of viable tissue between individual lesion segments.

View larger version (85K): [in this window] [in a new window]   Fig 3. Photo animation of the extracardiac Maze as seen from (a) the left pericardium, (b) the posterior left atrium, and (c) the right pericardium. The numbers designate ablation lines.

The device is then repositioned behind the SVC, from medial to lateral, behind the right pulmonary veins, and then behind and medial to the IVC. Lesion 6, the coronary sinus lesion, originates at the location of the Thebesian valve on the medial and inferior surface of the right atrium and extends behind the IVC towards the right inferior pulmonary vein. The device is withdrawn behind the right pulmonary veins to create lesion 7. The device is repositioned along the interatrial groove to create lesion 8 and complete the right pulmonary vein isolation. The device extends from the right pulmonary veins across the right atrium to create lesion 9. Lesion 10 extends from SVC to IVC along the lateral right atrium. The left atrial appendage is excluded or ligated (lesion 11).

The Ex-Maze procedure was performed during 44 concomitant cardiac procedures for patients with atrial fibrillation; of these, 82% of the patients had persistent or permanent atrial fibrillation. The average left atrial size was 5.2 cm. The additional mean ± SEM operative time was 34 ± 4.7 minutes (range, 48 to 20 minutes). Thirty-eight of the 44 patients (86%) presented in the operating room in atrial fibrillation, and 27 (71%) converted to sinus rhythm during the lesion creation.

There were no complications related to the Ex-Maze procedure. Five patients received amiodarone for 4 weeks; the remaining patients did not receive class I or III antiarrhythmic drugs. At 1 month, 66% (21 of 32) patients were in sinus rhythm. At 3 months, 79% (26 of 33) patients were in sinus rhythm.

	Comment

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Numerous soft-tissue ablation tools and incomplete procedures have been described to treat atrial fibrillation. These efforts have reduced the complexity of the gold standard Cox Maze III procedure but have sacrificed the completeness of the procedure and demonstrated questionable outcomes. In most cases, these less invasive procedures have limited the lesion pattern to those created only on the left atrium; however, this approach focuses primarily on patients with paroxysmal atrial fibrillation. The best treatment for all types of atrial fibrillation remains the full Maze III lesion pattern, addressing both the left and right atria. The advantages of the Ex-Maze include the ability to:

• perform all ablation lines on the epicardium of the beating heart,

• immediately verify the success of the procedure by the inability to pace outside the pulmonary veins or by the spontaneous conversion of atrial fibrillation to sinus rhythm during lesion creation; and

• see the ablations on the epicardium and, therefore, create continuous lesion patterns.

The Ex-Maze procedure avoids incomplete treatment patterns and pursues a treatment option for all patients with paroxysmal, persistent, or permanent atrial fibrillation.

Because the Ex-Maze does not include cryoablation of the mitral or tricuspid valve annulus, it is not an exact Maze procedure as Cox and colleagues described [3]. Persistent conduction pathways and recurrent atrial arrhythmias (ie, atrial flutter) are theoretically possible [4]. In addition, the right atrial appendage is not excised and the interatrial septum remains intact. However, the Ex-Maze treats both the left and the right atria and is performed without a cross clamp or atriotomy. Diligent creation of the biatrial Ex-Maze lesion pattern resulted in spontaneous conversion to sinus rhythm during lesion creation, signifying interruption of clinically significant macro-reentrant circuits. Of the patients who converted to sinus rhythm during the procedure, 94% did so during one of the lesions that connected the left atrium to the right atrium (eg, lesion 6 or 9 in Fig 1).

The Ex-Maze procedure is an uncomplicated and potentially effective solution for patients with paroxysmal, persistent, or permanent atrial fibrillation who undergo concomitant cardiac procedures. Long-term follow-up at 1, 3, 6, and 12 months to evaluate the clinical success of this procedure is underway.

	References

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1. Arcidi JM, Millar RC. Evolution of the Maze III procedure: are modifications necessary? Thorac Cardiovasc Surg 1999;47(suppl 3):362-364.[Medline]
2. Cox JL, Ad N. New surgical and catheter-based modifications of the Maze procedure Sem Thorac Cardiovasc Surg 2000;12:68-73.[Medline]
3. Cox JL, Boineau JP, Schuessler RB, Jaquiss RDB, Lappas DG. Modification of the Maze procedure for atrial flutter and atrial fibrillation: rationale and surgical results J Thorac Cardiovasc Surg 1995;110:473-484.[Abstract/Free Full Text]
4. Shah D, Haissaguerre M, Jais P, et al. High-density mapping of activation through an incomplete isthmus ablation line Circulation 1999;99:211-215.[Abstract/Free Full Text]

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Andy C. Kiser Gerhard Wimmer-Greinecker Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kiser, A. C. Articles by Chitwood, W. R. Search for Related Content PubMed PubMed Citation Articles by Kiser, A. C. Articles by Chitwood, W. R. Related Collections Extracorporeal circulation