Ann Thorac Surg 2007;84:1412-1413
© 2007 The Society of Thoracic Surgeons
How To Do It
Lateral Placement of Bipolar Clamp Facilitates Pulmonary Vein Isolation
Eric W. Schneeberger, MD*,
Robert M. Osterday, BS, PA-C
Department of Cardiothoracic Surgery, University of Cincinnati, Cincinnati, Ohio
Accepted for publication March 7, 2007.
* Address correspondence to Dr Schneeberger, Department of Cardiothoracic Surgery, ML 0558, University of Cincinnati, Albert B Sabin Way, Cincinnati, OH 45267 (Email: william.schneeberger{at}uc.edu).
| Dr Schneeberger discloses that he has a financial relationship with AtriCure, Inc.
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Abstract
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The surgical management of atrial fibrillation is becoming more commonplace with the procedure of pulmonary vein isolation forming the cornerstone of the treatment of atrial fibrillation. In this article a technique is described to introduce a dry bipolar radiofrequency clamp into the chest through a lateral port sized incision to safely effect pulmonary vein isolation in patients with low ejection fractions undergoing a concomitant mini-maze procedure. Confirmation of the transmurality and effectiveness of the lines of ablation is shown by the demonstration of bidirectional block to and from the pulmonary veins.
Patients with low ejection fractions who also have coronary artery or valve disease frequently have a history of paroxysmal or continuous atrial fibrillation and are believed to be reasonable candidates for surgical correction of their atrial fibrillation. Initially we believed that with a median sternotomy, isolation of the pulmonary veins would be technically easy while using a dry bipolar radiofrequency clamp. However, despite the fact that multivessel off-pump coronary artery bypass grafting is usually feasible, these patients will often not tolerate the lifting of their ventricles to expose the left-sided pulmonary veins and become profoundly hypotensive when their pulmonary veins are clamped with their ventricles elevated. In addition, patients with low ejection fractions undergoing a valve procedure often will not tolerate lifting of their ventricles without having a lot of ectopy, even after they are on bypass. We believe that the demonstration of bidirectional block of pulmonary vein isolation is important, and for this to be effectively demonstrated the patient needs to be in sinus rhythm. For this reason, a modification of our dry bipolar radiofrequency pulmonary vein isolation technique was introduced to minimize the effect that placement of the clamp on the left-sided veins had on the hemodynamics and rhythm.
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Technique
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There were two groups of patients: (1) patients with a history of atrial fibrillation and coronary artery disease in whom the plan was to perform off-pump coronary artery bypass grafting and a mini-maze procedure (n = 7), and (2) patients with valvar disease and atrial fibrillation (n = 5). Those planned for off-pump coronary artery bypass grafting had a standard median sternotomy performed. Prior to grafting, but after the graft material (ie, internal mammary artery, radial, or saphenous veins, or a combination of these) had been prepared, the mini maze was performed [1–5]. In patients having a valve procedure, dry bipolar radiofrequency pulmonary vein isolation is usually performed before the commencement of bypass, but may be done after going on bypass, depending on the patient’s hemodynamic status. Lifting a large, low ejection fraction heart in both these types of patients often causes acute circulatory embarrassment and altered rhythm that makes confirmation of bidirectional block of the pulmonary vein isolation impossible.
To this end, P waves are sensed on the left superior and inferior pulmonary veins by looking over the top of the heart by depressing the left atrium with a sponge stick (see Fig 1). The ligament of Marshall is also able to be divided after pushing down on the left atrium and retracting the left pulmonary artery in a cephalad direction. After this, a 12-mm incision, the size of a standard port site, is made in the left chest just lateral and inferior to the nipple usually in the anterior to mid axillary line in the fifth or sixth interspace. A lighted dissector (Lumitip [AtriCure, Inc, West Chester, OH]) is then introduced through this small incision and is able to be passed into the chest anterior to the lung, into the pericardium and directed around the left-sided pulmonary veins. In this fashion, using the GlidePath tape technology (AtriCure, Inc), the left-sided ablation clamp (Endo xcL [AtriCure, Inc]) is then able to be easily passed around the left pulmonary veins (see Fig 1). The position of the clamp can be checked by looking over the top of the heart and by depressing the left atrium to view the tips of the clamp just below the left pulmonary artery. Ablations are then performed. Next, sensing and pacing are performed on the superior and inferior pulmonary veins and inlet and outlet (bidirectional) block of the pulmonary veins is demonstrated.
The right-sided pulmonary vein ablation is then done with the left-sided AtriCure ablation clamp (Endo xcL) by placing the device from above downward so as to maintain the curvature of the device onto the left atrial cuff that subtends the right-sided pulmonary veins (see Fig 1).
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Results
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Twelve patients had their pulmonary veins isolated using this technique because of the large size of their ventricles. One of the patients who underwent a valved conduit replacement of his ascending aorta and two coronary artery grafts had an extreme reaction to protamine and died shortly after the procedure of diffuse cerebral hypoxia. Of the remaining patients with valve disease, 3 of the 4 were in sinus rhythm after a minimum of 6 months follow-up.
Of the 7 patients with coronary artery disease, 1 patient died 6 months after the surgery in congestive cardiac failure, but was noted to be in sinus rhythm at the time. Another patient was in atrial fibrillation, but was feeling very well and did not wish to have any other studies performed. Another patient had recently been troubled with arrhythmias, which on continuous halter were shown to be frequent premature atrial contractions and occasional premature ventricular contractions. Two of these patients were lost to follow-up. The remaining 3 patients were in sinus rhythm.
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Comment
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We have performed this procedure on a number of patients who had either paroxysmal or permanent atrial fibrillation and who were undergoing off-pump coronary artery bypass grafting or valve surgery. Most of them have had low ejection fractions and therefore large hearts. It was found that elevating the ventricle to work on the pulmonary veins produced profound hypotension or severe disturbance of rhythm in most of the patients. Subsequently, this interfered with our ability to prove bidirectional block of the pulmonary vein isolation. By introducing the clamp from a lateral position and staying effectively posterior to the ventricle, it has been possible to perform this procedure with much less interference to the cardiac out put and intrinsic rhythm. The laterally situated port can then serve as a left-sided chest tube site.
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References
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- Haissaguerre M, Jais P, Shah DC, et al. Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins N Engl J Med 1998;339:659-666.[Abstract/Free Full Text]
- Pappone C, Rosanio S, Oreto G, Santinelli M. Circumferential radiofrequency ablation of pulmonary vein ostia: a new anatomic approach for curing atrial fibrillation Circulation 2000;102:2619-2628.[Abstract/Free Full Text]
- Kanagaratnam L, Tomassoni G, Schweikert R, et al. Empirical pulmonary vein isolation in patients with chronic atrial fibrillation using a three-dimensional nonfluoroscopic mapping system: long-term follow-up Pacing Clin Electrophysiol 2001;24:1774-1779.[Medline]
- Oral H, Pappone C, Chugh A, et al. Circumferential pulmonary-vein ablation for chronic atrial fibrillation New Engl J Med 2006;354:934-941.[Abstract/Free Full Text]
- Morady F. Catheter ablation of supraventricular arrhythmias Pacing Clin Electrophysiol 2004;27:125-142.[Medline]
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