Ann Thorac Surg 2009;87:1592-1595. doi:10.1016/j.athoracsur.2008.10.014
© 2009 The Society of Thoracic Surgeons
Case Reports
Epicardial Electrical Isolation of the Right Atrial Appendage on the Beating Heart With an Infrared Coagulator
Hiroshi Kubota, MD, PhDa,*,
Kenichi Sudo, MD, PhDa,
Shinichi Takamoto, MD, PhDb,
Kunihiko Tonari, MD, PhDa,
Tatsuo Fujiki, MDa,
Hidehito Endo, MDa,
Hiroshi Tsuchiya, MDa,
Akira Furuse, MD, PhDc
a Department of Cardiovascular Surgery, Kyorin University, Tokyo, Japan
b Department of Cardiac Surgery, JR Tokyo General Hospital, Tokyo, Japan
c Department of Cardiac Surgery, Tokyo University, Tokyo, Japan
Accepted for publication October 8, 2008.
* Address correspondence to Dr Kubota, Department of Cardiovascular Surgery, Kyorin University, 6-20-2, Shinkawa, Mitaka, Tokyo, 181-8611, Japan (Email: kub{at}kyorin-u.ac.jp).
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Abstract
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To determine the clinical efficacy of application of infrared energy to the beating heart as a means of creating electrical blocks, an original infrared coagulator (KIRC-119; Phomec Inc, Tokyo, Japan) was applied to the atrium of a patient with atrial fibrillation. A postoperative electrophysiologic study was performed to confirm its efficacy. The coagulator was applied epicardially to the beating heart concomitant with an on-pump beating heart coronary artery bypass graft procedure. Sinus rhythm was restored during the operation, and the electrophysiologic study revealed that a bidirectional block had been created on the right atrial appendage. The infrared coagulator may facilitate performance of the epicardial Maze procedure on the beating heart.
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Introduction
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Radiofrequency, lasers, microwaves, cryo, and ultrasound are listed as effective energy sources for achieving atrial ablation. They are effective on the cardioplegic arrested heart, but creating transmural atrial lesions is more difficult when they are applied to the beating heart on the epicardial side. The inner blood flow of the atrium reduces the thermal effect on the endocardial side. In a canine study, infrared rays were used to create a transmural atrial lesion on the beating heart without injuring either the epicardium or endocardium and without causing any complications.
In the KIRC-119 infrared coagulator (Phomec Inc, Tokyo, Japan), light from a tungsten-halogen lamp is focused by a reflector into a light-conducting quartz rod with a diameter of 10 mm and emerges as 35-W/cm2 near-infrared light energy (wavelength, 400 to 1600 nm; peak wavelength, 850 nm). The distal exit plane of the light-conducting rod is connected to a cylindrical artificial sapphire tip with a diameter of 10 mm. When the sapphire tip is pressed onto the epicardium, light energy is absorbed by the myocardium, and when the tissue temperature reaches about 100°C, photocoagulation results. In this report we present a case in which the infrared coagulator was used clinically on the patient's beating heart. The patient's sinus rhythm has been maintained throughout the 3 years after the operation.
On August 25, 2005, a 63-year-old man was referred to our hospital because of a complaint of chest oppression. He was diagnosed with unstable angina pectoris. Emergency coronary angiography revealed 75% stenosis of the left main trunk, 60% stenosis of the proximal left anterior descending artery, and 60% stenosis of the middle portion of the left circumflex artery. The left ventricular ejection fraction was 0.40. Echocardiography showed anteroseptal hypokinesis of the left ventricle but no valvular dysfunction. The diameter of the left atrium was 34 mm. The electrocardiogram (ECG) showed ST depression in leads II, III, aVF, and V2through V6. No Q waves were detected. The ECG also showed atrial fibrillation (AF), and the maximum voltage of the f wave in V1 was 0.2 mV. The serum creatine kinase-MB fraction level was 3.4 IU/L, and the serum troponin-I level was 0.96 ng/mL.
According to his family physician, the patient had an 18-month history of AF. Because of his hemodynamic instability, an intraaortic balloon pump was inserted. After obtaining his informed consent, including to the use of the infrared coagulator to treat the AF, the patient was transferred to the operating room immediately after the coronary angiography and emergency coronary artery bypass grafting (CABG) was performed.
The pericardium was opened through a median sternotomy, and the cardiopulmonary bypass (CPB) was established. The left ventricle was vented with a cannula inserted through the right superior pulmonary vein. Two CABGs with saphenous vein were performed, one to the left anterior descending coronary artery and the other to the left circumflex coronary artery. A left internal thoracic artery was not used because enzyme leakage was detected and it was thought that earlier revascularization would be better.
Next, tapes was passed around the superior vena cava (SVC), the inferior vena cava (IVC), and the transverse sinus to achieve good left atrial exposure. A total CPB was established by snaring the tapes around the SVC and IVC.
Epicardial ablation was performed by applying the KIRC-119 infrared coagulator. The duration of the each application was 10 seconds: two ablations of 4 seconds, 2 seconds apart. Ablation was started in the right atrium (RA). The root of the right atrial appendage (RAA) was encircled, and the free wall of the RA was ablated from the RAA-encircling lesion to the IVC. Vertical ablation was performed from this coagulated line to the tricuspid annulus. The opposite side of the RA was ablated from the RAA-encircling lesion to the roof of the left atrium (LA), and a box lesion encircling the pulmonary vein (PV) was created. Finally, the left atrial appendage (LAA) was encircled, and a linear connecting lesion between the LAA-encircling lesion and the LA box lesion was created. After all of the lesions were completed, a pair of electrodes was sutured to the RAA and another pair to the free wall of the RA.
Soon after returning the patient to the intensive care unit, an ECG and atrial potentials were recorded with an HPM 4500 polygraph (Fukuda Denshi, Tokyo, Japan). Two weeks later, ECGs were recorded in the same manner. The recording conditions were (1) spontaneously beating heart, (2) overdrive pacing from the RA free wall, and (3) overdrive pacing from the RAA.
The AF spontaneously converted to sinus rhythm during the operation. No potentials were detected within the RAA-encircling lesion during spontaneous beating, but the free wall of the RA exhibited potentials synchronous with the sinus rhythm (Fig 1). During overdrive pacing from the RA, the cardiac rhythm was synchronous with the pacing. Overdrive pacing from the RAA did not affect the cardiac rhythm, which was a sinus rhythm (Fig 2).
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Fig 1. Atrial potentials recorded by the attached electrodes. Atrial potentials synchronous with the sinus rhythm were detected at the right atrial (RA) free wall. No atrial potentials were detected within the right atrial appendage (RAA) encircling lesion. Only the small smooth curve caused by RAA movement was seen.
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The results of the electrophysiologic study performed 2 weeks after the operation were the same. Persistent bidirectional block was confirmed. Regular sinus rhythm was confirmed by a postoperative 24-hour Holter monitor, and no supraventricular tachyarrhythmia was observed. An antiplatelet drug (aspirin, 81 mg/d) was started and continued. The patient recovered well, with no complications, and as of 3 years after the operation, his sinus rhythm has been maintained without the use of any antiarrhythmia drugs.
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Comment
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The KIRC-119 infrared coagulator was developed by modifying the prototype IRK-151 infrared coagulator (Lumatec, Deisenhofen, Germany). The results from a series of experiments that were performed with the KIRC-119 coagulator have been reported [1–3].
In the first experiment, the efficacy of the infrared coagulator was examined in canine beating hearts. The maximum depth of the lesions created in the right ventricle was 10.3 mm after ablation for 21 seconds. This was a transmural lesion, and there was no injury to the epicardium or endocardium. The ablated myocardium exhibited well-demarcated photocoagulation necrosis, with no carbonization or vaporization. Deposition of hemosiderin, invasion by macrophages, and increased juvenile elastic fibers were observed in the chronic phase. The myocardium did not regenerate [1].
In the second experiment, the Maze III procedure was performed on canine cardioplegic arrested hearts. Instead of being used to create a lesion encircling the PV, the coagulator was used to create a series of overlapping circular lesions from the endocardium. The postoperative electrophysiologic study showed that the LA within the PV-encircling coagulation area had been isolated electrophysiologically [2].
In the third experiment in a canine AF model, instead of making all of the incisions usually required for Maze procedures, the infrared coagulator was applied epicardially on the beating heart to create a series of overlapping linear lesions that conformed to the incision line in the Maze III procedure, except for the intraatrial lesion. The postoperative electrophysiologic study confirmed electrophysiologic isolation of both atrial appendages and within the PV-encircling lesion, and sustained AF could no longer be induced [3]. A photograph of a well-demarcated encircling lesion on the RAA created in this experiment is shown in Figure 3.
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Fig 3. The internal appearance of the lesion encircling the right atrial appendage (canine experiment). Well-demarcated degenerated myocardium is seen. Epicardial application of the infrared coagulator enabled the creation of a continuous encircling transmural lesion. Note that all the complicated trabecular structures are discolored.
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On the basis of these results, we applied the KIRC-119 coagulator in the case reported here. Although it is important to ablate between the encircling lesion and the mitral annulus in the Cox Maze III procedure, the isthmus line was omitted, because the safety of using the device on the human coronary sinus wall has not been demonstrated, and it was difficult to expose a good operative field that was safe enough to prevent coronary sinus injury. In the case reported here, the RAA was electrophysiologically isolated and the heart converted to sinus rhythm during the operation. The electrical block was confirmed immediately after the operation and again 2 weeks after the operation. We can conclude that the KIRC-119 coagulator created a continuous encircling transmural lesion in the RAA.
The electrophysiologic examination of our patient was focused on the RAA. To avoid injury to the LA, the electrode was not sutured to the posterior wall of the LA or the LAA. The fact that it was possible to create a bidirectional electrical block with the KIRC-119 coagulator on the RAA, which is one of the most difficult sites in which to create the transmural lesions, encourages us to attempt the off-pump epicardial Maze procedure.
Total CPB was performed in our patient because of the hemodynamic instability. Use of the total CPB provides two advantages in terms of performing the epicardial ablation. It markedly reduces the inner blood flow, which reduces the photothermal effect on the myocardium, and it facilitates creation of the transmural lesion. It is easy to expose the posterior wall of the LA of the exsanguinated heart. The major risk posed by the off-pump beating epicardial Maze procedure with the KIRC-119 coagulator through the median sternotomy is thought to be the hemodynamic instability caused by the exposure of the posterior wall of the LA, especially of the segment parallel to the coronary sinus.
Our patient recovered with no neurologic complications. To develop an ablation device, it is important not only to produce the transmural lesion but also to preserve the endocardium and epicardium to prevent thromboembolism and atrial perforation. The photoenergy of the infrared coagulator passes through the epicardium and endocardium, because both of them are translucent, and when the energy reaches the myocardium, a higher temperature is transmitted.
Accord and colleagues [4] performed a detailed postmortem histologic evaluation of microwave-induced lesions after epicardial pulmonary vein isolation to treat AF in 3 patients who died of nonablation-related causes. All 3 patients were in sinus rhythm before death. Thirteen tissue samples from the box lesions encircling the pulmonary veins were microscopically examined for transmurality, and transmural lesions were observed in only 3 samples. No histologic damage was observed in 3 samples, and the transmural extent of myocardial damage in the remaining samples was a mean of 64% ± 13% (range, 48% to 82%). Although the authors concluded that lesion transmurality cannot be assumed even after using the validated approach of epicardial beating heart ablation and satisfactory clinical results have been obtained, there is no question about the importance of creating a transmural lesion to achieving the same AF conversion ratio as by the gold standard "cut and sew" Maze procedure.
Many results of treatment of AF clinically by various means have been reported, and various modifications of the ablation line have also been reported [5–7]. It will be important to show that the device used is capable of producing a continuous transmural lesion in the atrium and of creating an electrophysiologic conduction block to assess the efficacy of any new procedure.
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Acknowledgments
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This work was supported by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education and Science in 1994, 1995, 2000, and 2001 to 2003; a Japan Heart Foundation/Pfizer Grant for Cardiovascular Disease Research in 2000; and by the Fujita Memorial Fund for Medical Research in 2001.
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References
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- Kubota H, Furuse A, Takeshita M, Kotsuka Y, Takamoto S. Atrial ablation with an IRK- 151 infrared coagulator Ann Thorac Surg 1998;66:95-100.[Abstract/Free Full Text]
- Kubota H, Takamoto S, Takeshita M, Miyaji K, Kotsuka Y, Furuse A. Atrial ablation using an lRK-151 infrared coagulator in canine model J Cardiovasc Surg 2000;4:835-847.
- Kubota H, Takamoto S, Furuse A, et al. Epicardial maze procedure on the beating heart with an infrared coagulator Ann Thorac Surg 2005;80:1081-1086.[Abstract/Free Full Text]
- Accord RE, van Suylen RJ, van Brakel YJ, Maessen JG. Post-mortem histologic evaluation of microwave lesions after epicardial pulmonary vein isolation for atrial fibrillation Ann Thorac Surg 2005;80:881-887.[Abstract/Free Full Text]
- Deneke T, Khargi K, Grewe PH, et al. Left atrial versus bi-atrial Maze operation using intraoperatively cooled-tip radiofrequency ablation in patients undergoing open-heart surgery: safety and efficacy J Am Coll Cardiol 2002;39:1644-1650.[Abstract/Free Full Text]
- Khargi K, Deneke T, Haardt H, et al. Saline-irrigated, cooled-tip radiofrequency ablation is an effective technique to perform the maze procedure Ann Thorac Surg 2001;72:S1090-S1095.[Abstract/Free Full Text]
- Gaita F, Gallotti R, Calo L, et al. Limited posterior left atrial cryoablation in patients with chronic atrial fibrillation undergoing valvular heart surgery J Am Coll Cardiol 2000;36:159-166.[Abstract/Free Full Text]
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Abstract
Introduction
