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Ann Thorac Surg 2006;82:1327-1331
© 2006 The Society of Thoracic Surgeons
Pediatric Cardiology and Cardiac Surgery Department, GUCH Unit, "E. Malan" Center, Policlinico San Donato, San Donato Milanese, Italy
Accepted for publication May 4, 2006.
* Address correspondence to Dr Giamberti, Pediatric Cardiac Surgery Department, GUCH Unit, Policlinico San Donato, Via Morandi 30, San Donato M.se (Mi) 20097, Italy (Email: alegia{at}hotmail.com).
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Abstract |
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METHODS: During a 26-month period between September 2002 and December 2004, 15 patients more than 40 years old with ASD and atrial arrhythmia underwent elective surgical closure of the defect and intraoperative IRF ablation. All patients had supraventricular arrhythmias: 8 had permanent atrial fibrillation, whereas 7 had previous episodes of atrial flutter or intra-atrial reentry tachycardia. The biatrial approach (Cox-Maze III procedure) was used in 7 patients and a right-sided Maze procedure (ablation lines on the right atrium only) was carried out in the remaining 8 patients.
RESULTS: All patients survived the procedure. Fourteen patients left the operating room in sinus rhythm and 1 had a pacemaker implanted. There were no complications resulting from the IRF ablation. All 15 patients survived over the average follow-up period of 24 months. Thirteen patients were still in sinus rhythm, 1 had pacemaker rhythm, and only 1 (1 of 15; 6.5%) suffered a recurrence of atrial fibrillation 3 months after the procedure.
CONCLUSIONS: We suggest adding intraoperative IRF ablation during surgical closure of an ASD in all adult ASD patients with arrhythmias. The IRF ablation is easy to perform, safe, and effective.
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Introduction |
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It has been proposed that surgical treatment of the atrial arrhythmia with a Cox-Maze procedure or a right-sided Maze procedure could be performed at the same time as the closure of the ASD [5–7], but this remains a controversial strategy given the technical complexity of the procedure, which carries the risk of postoperative bleeding and requires prolonged aortic cross-clamping and cardiopulmonary bypass. Research into simplifying these interventions suggest that the multiple surgical incisions could be replaced with linear lesions created by alternative energy sources such as radiofrequency.
We present our preliminary findings of surgical ASD closure combined with intraoperative irrigated radiofrequency (IRF) ablation in 15 adult patients and evaluate the effectiveness of the intraoperative ablation and the combined approach.
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Material and Methods |
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Eight patients had ostium secundum type ASD, 2 had ostium primum type ASD, 2 had sinus venosus ASD, and 3 had ostium secundum type ASD associated with tricuspid dysplasia, mitral valve prolapse, and scimitar syndrome. None of the patients had previously undergone cardiac surgery. Eight patients were in New York Heart Association (NYHA) functional class III and 7 were in NYHA functional class II.
All patients had supraventricular arrhythmias. Eight patients had permanent atrial fibrillation, 5 have had previous episodes of intra-atrial reentry tachycardia, and 2 patients had type I atrial flutter. The patients with intra-atrial reentry tachycardia and type I atrial flutter underwent electrophysiologic study. In patients with intra-atrial reentry tachycardia, the average heart rate was 116 ± 12 beats per minute and the duration of the atrial cycle was 520 ± 50 ms. The 2 patients with type I atrial flutter had heart rate of 120 and 115 beats per minute and atrial cycles lasting 500 ms and 520 ms, respectively. The mean PR duration was 0.141 ± 0.026.
Seven patients had received amiodarone treatment before surgical ablation, 3 had undergone several cardioversion procedures, and transcatheter ablation had been attempted unsuccessfully in 1.
Primary surgical closure of the ASD was performed on all patients using heterologous pericardial patch closure in 14 cases and direct suturing in 1. The associated surgical procedures were right atrial free wall reduction in 6 cases, tricuspid valve repair in 4, mitral cleft closure in 2, and mitral valve repair with annuloplasty and mitral ring in 1. The right atrial reduction was carried out in patients whose preoperative echocardiographically measured value of right atrial short axis and long axis exceeded normal values by at least 50%.
Monopolar IRF ablation (Cardioblate Surgical Ablation System; Medtronic, Inc, Minneapolis, MN) was performed in all patients. We used an irrigation flow rate of 5 mL/min, power of 30 to 40 W (40 W for the thicker atrial wall), pen movement of 0.5 cm/s, and ablation time of 10 s for each cycle. Ablation lines and surgical incisions were performed in a standard way in the right and left atrium. In the right atrium, we excised the appendage and removed a large part of the free wall in case of severe atriomegaly. Right atrial incisions were (1) from the amputated right atrial appendage toward the crista terminalis, and (2) from the middle of the right atriotomy toward the inferior part of the atrium (Fig 1). Right atrial ablation lines were as follows: (1) from superior vena cava (SVC) cannulation toward inferior vena cava (IVC) cannulation; (2) from the excised right atrial appendage to the tricuspid valve annulus and to the ASD; (3) from the crista terminalis to the ASD; (4) between the IVC and coronary sinus; and (5) between the IVC and tricuspid valve annulus (Fig 2).
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Results |
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During a mean follow-up of 24 months (range, 12 to 38), all 15 patients survived and all had an improvement of NYHA functional class (9 achieved NYHA functional class I and 6 reached class II). One patient (1 of 15;p 6.5%) had a recurrence of atrial fibrillation 3 months after the procedure. This patient was in AF before surgery and was the only patient with AF who underwent a right-sided Maze procedure. The arrhythmia in this patient responded to the reinstitution of antiarrhythmic treatment, and the patient had no further recurrences.
All patients underwent 24-hour electrocardiogram monitoring 3, 6, and 12 months after the operation. Data from the Holter monitoring showed that 13 patients were in sinus rhythm with a mean PR duration of 0.167 s ± 0.031 s without antiarrhythmic medication, 1 had a pacemaker rhythm, and 1 was in sinus rhythm but still receiving oral amiodarone treatment.
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Comment |
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Atrial arrhythmias, especially AF but also atrial flutter and supraventricular tachycardias, begin to occur more frequently in patients over the age of 40 and are one of the most important precipitating causes of heart failure [2]. It is not yet clear whether AF causes the heart failure or is a reflection of chronic right heart volume and pressure overload, and the long-standing left-to-right shunt.
Atrial flutter and fibrillation occur in 14% to 22% of adult patients with unoperated ASD [3, 4, 9], and AF persists in a high percentage of patients after surgical closure of the defect unless a direct antiarrhythmic intervention is performed. Brandenburg and colleagues [3] found that 88% of patients with ASD who were more than 44 years old with preoperative paroxysmal AF continued to have increasingly frequent paroxysmal AF, culminating in sustained AF. In a larger study, Berger and coworkers [4] showed that surgical correction of ASD in adults did not decrease the occurrence of AF. Even preoperative atrial flutter or paroxysmal supraventricular tachycardia can evolve into sustained postoperative AF [3]. Age more than 40 years old at the time of surgery, higher preoperative pulmonary artery pressure, preoperative atrial flutter or fibrillation, and postoperative atrial flutter or fibrillation or junctional rhythm are factors predisposing to the late postoperative AF [9]. Even after a successful defect closure, patients are exposed to the risks of stroke owing to arrhythmia-related thromboembolism and to the risks associated with chronic drug therapy (antiarrhythmic agents or warfarin) [7, 9, 10].
Older patients with ASD undergoing surgery must be evaluated carefully to determine the presence of AF and to access the need for arrhythmia surgery. Since the 1980s, the Cox-Maze III procedure has been the surgical procedure of choice for the management of AF refractory to medical treatment [11, 12]. This procedure is designed to eliminate AF while preserving intact atrioventricular nodal conduction and atrial contractility and prevents AF recurrence in more than 90% of adult patients, including those in whom the arrhythmia is associated with acquired or congenital heart disease [13, 14]. Theodoro and associates [7] proposed a modification of the Cox-Maze III procedure for patients with AF undergoing surgical treatment of right-sided congenital heart disease, the so called "right-side maze procedure" in which the line incisions are limited to the right atrium and atrial septum. Subsequent studies [5, 15] showed that the outcomes of the original Cox-Maze III procedures were better than those of the limited right-sided atrial Maze procedure in patients with AF. Nevertheless, the Cox-Maze III procedure remains a complex procedure that requires protracted surgical and cardiopulmonary bypass time, is associated with a high incidence of reopening the chest for bleeding [5, 13], and carries the risk of late pulmonary vein stenosis [13].
In an attempt to simplify the technique, many modifications have recently been developed, including changes in atriotomies [16] and replacement of the multiple surgical incisions, in which linear lesions are created, by alternative energy sources such as cryoablation [15, 17, 18] and dry or irrigated radiofrequency [19–21].
The problem in the presence of a congenital heart defect is the thickness of the atria and the variance of the anatomy. The aim of intraoperative ablation is to obtain a reliable transmural line of block in these thick atria. The ablation achieved with a bipolar radiofrequency ablation system is absolute, but such a system can be rarely used in patients with complex congenital heart defects because it is not feasible or is extremely difficult, requiring much exceptionally dangerous dissection.
A major drawback of dry radiofrequency systems is their inability to penetrate deep into tissue. With monopolar dry radiofrequency energy, high power settings must be used in order to achieve a transmural lesion, and an associated risk of pulmonary vein perforation or esophageal injury has been reported [22]. Higher power dry radiofrequency can cause tissue temperature to exceed 100°C. At this point, tissue fluid boils, thus increasing impedance and limiting the size of the lesion formed.
When an irrigated radiofrequency system is used, the power can be set at a higher level without fear of desiccation, charring, and increased impedance [23]. The cooling effect of the irrigating saline together with the higher power delivered allows a deeper and larger area of tissue to be heated, thus enabling transmural ablation [23]. We used monopolar irrigated radiofrequency on all our patients. As previously reported [21], there were no unforeseen complications from the use of irrigated radiofrequency, and based on our findings, we can confirm that the system is simple to use and effective.
The ablation on the right and left atria generally requires 15 minutes. The excisions and incisions can be performed on the right side, with the aorta declamped, after the ASD closure.
There are few data available in the literature [24] about the use of IRF ablation in congenital heart defects, especially in adults with ASD. Based on data from Deal and colleagues [15] Mavroudis and coworkers [18], our current policy is to perform Cox-Maze III ablation in patients with preoperative AF and to reserve the modified right-sided Maze ablation for patients with preoperative episodes of atrial flutter or supraventricular tachycardia, or both.
All patients were discharged on oral amiodarone treatment for 3 months and aspirin treatment for 6 months. Aspirin treatment was given to reduce the risks of left atrial thrombi related to the electrical isolation of the left atrial appendage. This approach prevented the recurrence of postoperative AF in more than 90% of our patients. The only patient who had postoperative recurrence of AF was the very first patient enrolled in the trial. A right-side Maze procedure was carried out in this patient despite the presence of preoperative AF. We now consider that this management was a mistake.
The reported rate of arrhythmias during the first 3 months after the standard Cox-Maze III procedure ranges from 40% to 50% [11]. The rate of recurrence of arrhythmia in the first month after the right-sided Maze procedure is also high [7]. Our results, after a mean follow-up of 24 months, seem to indicate a significant lack of recurrent arrhythmias. These data are encouraging, and we are extending the trial to patients with other complex congenital heart defects such as Fontan patients or those with Fallot's tetralogy [25].
In conclusion, for adult patients with ASD and arrhythmias, we suggest adding intraoperative IRF ablation to the surgical closure of the defect. We perform left- and right-sided ablation (Cox-Maze III) on patients in AF, and reserve the ablation on the right atrium to only those patients with prior episodes of supraventricular arrhythmia after electrophysiologic study. In our experience, the monopolar IRF ablation system is easy to use, safe, and effective. Although this trial was conducted on a limited number of patients, there were no complications related to the IRF ablation.
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References |
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This article has been cited by other articles:
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  L. A. Bockeria, A. S. Revishvili, Aziz. H. Melikulov, and S. Y. Serguladze Irrigated monopolar radiofrequency ablation in surgical treatment atrial fibrillation. Interactive CardioVascular and Thoracic Surgery, February 1, 2008; 7(1): 82 - 83. [Full Text] [PDF]
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Y.-Q. Lai, J.-H. Li, J.-W. Li, S.-D. Xu, Y. Luo, and Z.-G. Zhang Concomitant irrigated monopolar radiofrequency ablation of atrial fibrillation in adults with congenital heart disease Interactive CardioVascular and Thoracic Surgery, February 1, 2008; 7(1): 80 - 83. [Abstract] [Full Text] [PDF]
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