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J Thorac Cardiovasc Surg 2003;125:1537-1538
© 2003 The American Association for Thoracic Surgery
Brief Communications |
From the Departments of Cardiothoracic Surgery, University of Tokyo, Tokyo, Japan.
Received for publication Aug 27, 2002. Accepted for publication Oct 9, 2002. Address for reprints: Toshiya Ohtsuka, MD, Department of Cardiothoracic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 Japan (E-mail: ootsuka-cvs{at}umin.ac.jp).
The maze procedure, originated by Cox and colleagues,
1,2 has become the criterion standard for the surgical treatment of chronic or paroxysmal atrial fibrillation. In this procedure, both atria are electrically separated into small compartments by atriotomy and cryoablation to prevent electrical macro reentry at each compartment, and a conduction from the sinus node to the atrioventricular node is preserved. In the usual left atrial (LA) maze procedure, endocardial cryoablation is performed directly through a right-sided left atriotomy, which is created anterior to the pulmonary veins (PVs).
In a limited number of patients in whom the mitral valve was left untouched, a video-assisted minicardioscopic approach through a small cut in the fossa ovalis or a congenital atrial septal defect (ASD) was used instead of a direct left atriotomy approach. This report describes the method and clinical outcomes of this technique.
Patients and method
This technique was applied to 3 consecutive male patients with chronic atrial fibrillation and concomitant nonmitral cardiac diseases: ASD (secundum type), severe tricuspid regurgitation (TR) resulting from previous endocarditis, and coronary artery disease (CAD). The durations of arrhythmia were 10 months, 1 year, and 3 years, respectively, and the sizes of the LA on longitudinal echocardiographic view were 52, 54, and 50 mm, respectively. The fibrillation waves were greater than 1 mV in the V1 electrocardiographic lead in each case. Although preoperative electrophysiologic tests were not available for any of the patients, a maze procedure was performed concomitantly. A 3-mm diameter, 30° rigid endoscope (Karl Storz GmbH & Co, Tüttlingen, Germany), and T-shaped and straight cryoablation probes (CooperSurgical, Inc, Shelton, Conn) were used.
Cardiopulmonary bypass was established with bicaval drainage and LA venting through the right upper PV. In the TR and CAD cases, bicaval occlusion was performed, and the Kosakai procedure, 3 a modified maze procedure that uses incisions and cryoablation, was performed for the right atrium. Thereafter an aortic crossclamp was placed and cardiac arrest was performed, and the T-shaped cryoablation probe and cardioscope were introduced into the LA through a 1-cm cut at the fossa ovalis or ASD. The anatomy of the LA, including the ostia of each PV and the LA appendage (LAA), was precisely identified videoscopically, and videocardioscopic endocardial cryoablation was performed (Figure 1). Cryolesions were created around the four PVs, between the PV-encircling cryolesion and the midst of the posterior mitral valvular annulus, and between the PV-encircling lesion and the base of the LAA. Finally, the cryolesion between the PV-encircling lesion and the septotomy or ASD was created with the straight cryoprobe. Each cryoablation was 2-minutes long, and the temperature was -75°C. Thereafter the septotomy or ASD was closed, the LAA was excised and closed, the LA was deaired, and the aorta was declamped. After the LA maze procedure, a right atrial maze procedure was performed in the ASD case, and tricuspid valve plasty and coronary artery bypass grafting were performed in the other 2 cases.
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Videocardioscopic LA-endocardial cryoablation required 24, 20, and 22 minutes of aortic crossclamping. No deaths or procedure-related morbidities occurred. After the operation, each patient recovered sinus rhythm. The follow-up periods were 7, 4, and 3 months in the ASD, TR, and CAD cases, respectively. With the oral intake of digoxin (0.25 mg) in the ASD and TR cases and atenolol (25 mg) in the CAD case, all 3 patients have maintained regular sinus rhythm.
Discussion
Cox 1 introduced the original maze procedure in 1991, and his group developed the Cox maze III technique with excellent clinical outcomes. 2 Today, although different energy sources (laser, microwave, and radiofrequency) have been applied endocardially or epicardially, 4,5 endocardial cryoablation is still considered the safest and most reliable method with acceptable transmurality and durability. Kosakai and associates 3 developed a modified method in which cardiotomies were reduced and cryoablation was used more extensively to minimize hemorrhage from atriotomies and preserve the sinus node artery. Their clinical results, including sinus rhythm recovery, were as good as the outcomes with the Cox method. Although it is limited to nonmitral cases, our cardioscopic technique is actually a modified Kosakai technique 3 in which the left atriotomy, except the LAA division, has been eliminated.
The 3-mm cardioscope is the most important tool in the technique described here. This miniscope, which was developed only recently, enables excellent intra-atrial visualization through a small septal entry.
In summary, although our experience is limited, videocardioscopic endocardial left-atrial cryoablation through a small septotomy or ASD is a feasible procedure. It has acceptable results and can be applied to nonmitral cases with atrial fibrillation.
References
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