Ann Thorac Surg 2008;85:303-304. doi:10.1016/j.athoracsur.2007.06.082
© 2008 The Society of Thoracic Surgeons
New Technology
Invited commentary
Takashi Nitta, MD
Cardiovascular Surgery, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-0022, Japan
Off-pump surgery for atrial fibrillation (AF) on the beating heart will benefit many patients with isolated and permanent AF who cannot presently be cured by existing pharmacological or nonpharmacological therapies. It is mandatory in the establishment of off-pump AF surgery to develop ablation devices that can create a safe and easy transmural, continuous lesion on the beating heart. Pulmonary vein isolation can be achieved by bipolar radiofrequency ablation devices without the use of cardiopulmonary bypass. These days a similar lesion can also be made by catheter-based ablation techniques. However, creation of lines of conduction block on the atrial free wall of the beating heart still remains an unresolved assignment. The heat-sink effect due to the warm blood flowing inside the atria interferes with the creation of transmural necrosis by epicardial ablation. Maintaining consistent contact with the irregular, curved surface of the atria on the beating heart has been another issue faced by epicardial ablation.
Kiser and colleagues [1] describe a novel ablation system that is capable of creating transmural, continuous lesions on the beating heart. Perfusion of saline cools the epicardial surface, allows the ablation power to be increased without charring the surface, and results in deeper thermal penetration and transmural necrosis. This technology is integrated with a suction feature that assures consistent contact of the device and atrial epicardium during ablation on the beating heart. The results of the experimental ovine study are promising. The pacing study revealed complete conduction block across the ablation lines, except in one animal in which the trabecula inside the appendage might have caused residual conduction. In the pathologic examination, all lesions demonstrated continuous and transmural degeneration. The final issue to be resolved in the establishment of off-pump AF surgery should be the extension of the lines of conduction block completely down to the mitral and tricuspid valve annuli. Because the atrioventricular grooves are covered with fat and the annuli located deep in the fat pads, it is truly challenging to make a transmural lesion in the atrium close to the annuli by epicardial ablation without any significant damage to adjacent structures. We all believe that innovative devices or procedures will emerge to make an off-pump AF procedure, hopefully by thoracoscopic approach, a reality in the near future.
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- Kiser AC, Nifong LW, Raman J, Kasirajan V, Campbell N, Chitwood Jr WR. Evaluation of a novel epicardial atrial fibrillation treatment system Ann Thorac Surg 2008;85:300-304.[Abstract/Free Full Text]
Related Article
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Evaluation of a Novel Epicardial Atrial Fibrillation Treatment System
- Andy C. Kiser, L. Wiley Nifong, Jai Raman, Vigneshwar Kasirajan, Nigel Campbell, and W. Randolph Chitwood, Jr
Ann. Thorac. Surg. 2008 85: 300-303.
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