Ann Thorac Surg 2002;73:320-321
© 2002 The Society of Thoracic Surgeons
How to do it
Epicardial ablation of atrial fibrillation on the beating heart without cardiopulmonary bypass
Domenico Mazzitelli, MD*a,
Chul-Hyun Park, MDb,
Kook-Yang Park, MDb,
Federico J. Benetti, MDc,
Ruediger Lange, MDa
a Department of Cardiovascular Surgery, German Heart Center, Munich, Germany
b Department of Cardiothoracic Surgery, GIL Medical Center, Inchon, South Korea
c Benetti Foundation, Rosario, Argentina
Accepted for publication October 10, 2001.
* Address reprint requests to Dr Mazzitelli, Department of Cardiovascular Surgery, German Heart Center at the Technical University, Lazarettstr 36, 80636 Munich, Germany
e-mail: mazzitelli{at}dhm.mhn.de
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Abstract
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The Cox-Maze procedure is the gold standard in surgical treatment of atrial fibrillation. Alternative techniques using cryoablation, radiofrequency, or microwaves have been proven to be equally effective. However, up to now, all techniques require the opening of the atria and, hence, the use of extracorporeal circulation. We describe a technique to perform epicardial ablation of atrial fibrillation on the beating heart without the use of cardiopulmonary bypass.
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Introduction
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The Cox-Maze procedure is the gold standard in surgical treatment of atrial fibrillation (AF). Alternative techniques using cryoablation, radiofrequency, or microwaves have been proven to be equally effective. However, until now, all techniques require the opening of the atria and, therefore, the use of extracorporeal circulation. We describe a technique to perform epicardial ablation of AF on the beating heart without the use of cardiopulmonary bypass (CPB).
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Technique
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We start with the dissection of the pericardial reflection between the superior vena cava and the right superior pulmonary vein. Then we perform the dissection toward the right inferior pulmonary vein, which must be completely separated from the inferior vena cava. At this point the first ablation lesions are performed. We use a flexible microwave ablation tool with a 40-mm-long tip. The energy is set at 65 W, and the application time is 90 seconds. Because the tip of the tool is flexible, it can be bent to completely encircle each one of the right pulmonary veins.
After the right superior pulmonary vein and the right inferior pulmonary vein have been isolated, they are joined with one or more additional ablation lines (Fig 1).

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Fig 1. Back view of pericardium. Schematic illustration of ablation lines connecting all pulmonary veins (dotted lines are ablation lines). (IVC = inferior vena cava; LIPV = left inferior pulmonary vein; LSPV = left superior pulmonary vein; RIPV = right inferior pulmonary vein; RSPV = right superior pulmonary vein; SVC = superior vena cava.)
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The next lesions are performed on the roof of the left atrium, starting from the right superior pulmonary vein toward the left superior pulmonary vein (Fig 2).
The lesion is completed placing the tool in the transverse pericardial sinus.

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Fig 2. Ablation line on the roof of the left atrium. (RAA = right atrial appendage; SVC = superior vena cava.)
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At this point the dissection of both the left pulmonary veins is performed. The heart is lifted to the right, either by placing deep pericardial sutures above the left phrenic nerve or with the help of a suction device placed at the apex of the heart. The dissection of the left pulmonary veins is performed in a similar manner as for the right side. After isolating both left pulmonary veins with circular ablations, they are joined with one or more linear lesions.
Now a linear ablation lesion between the left superior pulmonary vein and the left atrial appendage is performed, taking care not to injure the circumflex artery (Fig 3).
Then the left atrial appendage is ligated at its base. Alternatively, it may be closed with a pursestring suture.

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Fig 3. Ablation between left superior pulmonary vein (LSPV) and left atrial appendage (LAA). (PA = pulmonary artery.)
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The last step of the left atrial epicardial ablation consists of joining the right inferior pulmonary vein and left inferior pulmonary vein by a vertical lesion. The patient is put in Trendelenburg position, and gradual verticalization of the heart is achieved. Then the right inferior pulmonary vein and left inferior pulmonary vein are connected with linear lesions.
Epicardial ablation of AF was performed in a 46-year-old female patient who suffered from rheumatic mitral valve disease and chronic AF for more than 5 years. Preoperative transesophageal echocardiography showed no evidence of thrombi in the left atrium, which is considered a contraindication for the procedure. All the lesions were performed on the beating heart and before cannulation. Mitral valve replacement with a mechanical bileaflet prosthesis was then performed using standard CPB and moderate hypothermia. Conversion to normal frequent sinus rhythm was observed already before starting CPB and remained stable after coming off bypass until the third postoperative day.
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Comment
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The Cox-Maze operation still shows the most consistent results for surgical treatment of AF [1], but alternative techniques, which are less time-consuming, have proven to be effective, too [2, 3]. Up to now, only two reports exist about epicardial ablation of AF on the beating heart. In one publication, the procedures were started on the beating heart, but they were completed endocardially on standard CPB [4]. Melo and associates [5] described isolation of epicardial pulmonary veins without CPB using radiofrequency.
The present report focuses on the details of a new surgical technique. The application of microwave energy was found to be easy and effective. This study confirms that CPB may not be necessary for epicardial ablation of AF, which in this case was performed totally off-pump on the beating heart. Our experience could open new perspectives for a minimally invasive surgical approach to the treatment of AF and help to further expand the indications for surgical therapy.
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References
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Cox J.L., Jaquiss R.D., Schuessler R.B., Boineau J.P. Modification of the maze procedure for atrial flutter and atrial fibrillation. Surgical technique of the maze III procedure. J Thorac Cardiovasc Surg 1995;110:485-495.[Abstract/Free Full Text]
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Kim K.B., Huh J.H., Kang C.H., Ahn H., Sohn D.W. Modifications of the Cox-Maze III procedure. Ann Thorac Surg 2001;71:816-822.[Abstract/Free Full Text]
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Knaut M., Spitzer S.G., Karolyi L., et al. Intraoperative microwave ablation for curative treatment of atrial fibrillation in open heart surgery: the MICRO-STAF and MICRO-PASS pilot trial. Thorac Cardiovasc Surg 1999;47(Suppl):379-384.
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Benussi S., Pappone C., Nascimbene S., et al. A simple way to treat chronic atrial fibrillation during mitral valve surgery: the epicardial radiofrequency approach. Eur J Cardiothorac Surg 2000;17:524-529.[Abstract/Free Full Text]
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Melo J., Adragao P., Neves J., et al. Endocardial, and epicardial radiofrequency ablation in the treatment of atrial fibrillation with a new intra-operative device. Eur J Cardiothorac Surg 2000;18:182-186.[Abstract/Free Full Text]
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