| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Eur J Cardiothorac Surg 2003;24:223-230
© 2003 Elsevier Science NL
s Caynaka
a Department of Cardiovascular Surgery, Florence Nightingale Hospital, Kadir Has University Medical Faculty, Istanbul, Turkey
b Department of Anesthesia, Florence Nightingale Hospital, Kadir Has University Medical Faculty, Istanbul, Turkey
Received 15 October 2002; received in revised form 31 March 2003; accepted 1 April 2003.
* Corresponding author. Tel.: +90-212-239-8790; fax: +90-212-239-8791
e-mail: belh{at}turk.net
 |
Abstract |
|---|
 Top Abstract 1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
Key Words: Port access • Radiofrequency ablation • Maze
|
1. Introduction |
|---|
|
TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
The aim of this study was to assess the feasibility and efficacy of an irrigated RF system during port access mitral valve surgery and to evaluate early and mid-term results in terms of sinus rhythm restoration and outcome.
|
2. Materials and methods |
|---|
|
TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
Mean age was 53±0 in Group A and 50±8 in Group B (P=0.90). Rheumatic disease was dominant in both groups with a prevalence of 55 and 59% in Groups A and B, respectively (P=0.90). Patient characteristics are shown in Table 1.
|
2.2. Surgical procedure
After standard induction of anesthesia, patients underwent double lumen intubation for single lung ventilation. Following the administration of 2 mg/kg of heparin, a 17 F arterial cannula (DLP, Inc, Grand Rapids, MI) was introduced through the right internal jugular vein percutaneously to assist venous drainage during cardiopulmonary bypass (CPB). TEE monitorisation was used routinely to evaluate the results of valve repair and detect evacuation of air. Patients were positioned supine with the right shoulder elevated and external defibrillation pads were placed. A right lateral minithoracotomy (4–6 cm) in the fourth intercostal space was performed. A soft tissue retractor (Heartport Inc, Redwood City, USA) was used for the exposure of the surgical field, avoiding the division or traction of any rib. A 5 mm camera port (Storz, Karl Storz GmbH and Co, Tuttingen-Ger) was introduced through the fourth intercostal space front axillary line. A second port was introduced through the sixth intercostal space mid axillary line for left atrial venting and carbon dioxide insufflation, which began immediately after collapsing the right lung. Simultaneously, the right femoral artery and vein were prepared by means of a 2 cm oblique incision in the groin. CPB was established by femoro-femoral cannulation. A 18–20 F arterial cannula (DLP, Inc, Grand Rapids, MI) was used for arterial cannulation. Venous drainage was obtained by a 24–29 F femoral cannula (DLP, Inc, Grand Rapids, MI) and the 17–19 F arterial cannula previously inserted in the right internal jugular vein, thus allowing adequate venous drainage. The pericardium was opened 2 cm above and parallel to the phrenic nerve. Exposure was optimised with several pericardial stay sutures. Patients were cooled down to 28°C. Both vena cavae were encircled with tapes for a dryer operative field. A transthoracic clamp (Chitwood, Scanlan, Saint Paul, MN, USA) was introduced from the second intercostal space, front axillary line percutaneously. After cross-clamping of the aorta, blood cardioplegia was administered through a custom made (DLP) antegrade cardioplegia cannula inserted in the ascending aorta. The left atrium was opened parallel to the interatrial groove. The Heart Port atrial retractor system (Heart Port Inc, Redwood City, CA) was used for the exposure of the atrium.
2.3. Radiofrequency ablation
The Cardioblate (Medtronic Inc, MN, USA) RF ablation system consists of a power generator and a pen. This is a hand held unipolar RF ablation device. The electrode tip is irrigated with saline that cools the tissue and provides a low impedance path. The irrigation of the saline through the nine tip openings conducts RF current away from the tip creating a virtual electrode. During the procedure, the pen is slowly oscillated over the tissue. The power generator can produce a power output ranging from 20 to 30 watts/5 cc irrigation/min. The exact duration for each lesion varies according to tissue thickness, power setting and irrigation rate. Based on our personal experience and device guidelines, we most frequently used 25 watts with an irrigation rate of 5 cc/min. Experimental and clinical studies have suggested that these settings would allow to reach a tissue depth of 3–4 mm (average thickness of the left atrial tissue) in 15 s. The pen shaped probe allowed sufficient endothoracic movement and enabled the surgeon to perform precise ablation lines through a limited incision (Fig. 1
). The videoscopic vision allowed excellent view for the left atrium during the Maze procedure (Fig. 2
).
|
|
|
|
|
2.5. Technical details
The ablation preceded any other procedure, in order to avoid any damage to the suture lines due to heat produced by the RF energy. The TEE probe was always removed during the ablation to prevent any damage by the transmission of heat waves to the esophagus and cause injury.
To avoid any collateral damage to the circumflex coronary artery while performing the ablation line towards the mitral annulus, the P2–P3 segment was targeted.
The biatrial Maze procedure was applied in cases in which the right atrium had to be opened for a tricuspid valve inspection or an atrial septal defect or if the patient formerly had a history of atrial flutter. Otherwise the procedure was limited to the left side.
2.6. Postoperative management
All patients received temporary atrial and ventricular pacemaker wires at the end of the operation, for pacing or overdriving the atrium when necessary.
Since rhythm problems are common during the early postoperative period, patients in both groups received prophylactic amiodarone. An initial dose of 150 mg were given at the end of the operation intravenously followed by 0.5 mcg/kg/min for 24 h followed by 200 mg daily. The authors do not favour early cardioversion for patients in postoperative AF and reserve this for patients who are still in AF after 3 months. Antiarrhythmic medication was administered for 3 months in Group A and gradually discontinued afterwards. Patients in Group B received cordarone for 12 months. After 12 months, only patients who were in sinus rhythm continued to receive cordarone.
All patients underwent 72 h of Holter monitoring during their hospitalization. Left atrial transport function was evaluated 12 months after the operation by transthoracic echocardiography with Doppler analysis of mitral flow.
The anticoagulation management protocol was the same as that applied for routine open heart surgery. Patients receiving mechanical valves continued Coumadin (Du Pont Pharmaceuticals, Wilmington, DE) treatment. At discharge, all patients received coumadin, due to the high incidence of arrhythmias during this period. INR value was kept between 2.5 and 3 in patients who were in sinus rhythm and between 3 and 3.5 for patients who remained in AF. Coumadin was discontinued after 6 months, if the patient was in sinus rhythm and did not receive a mechanical valve. All other patients continued to receive coumadin.
|
3. Results |
|---|
|
TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
|
In Group A, intraoperative freedom from AF was 100% (76% SR, 24% pacemaker). At discharge, 81% of patients were free of AF. During 6 months, 1 year and over 1 year follow-up, 87.2, 93.6 and 92% of patients were free of AF, respectively.
In Group B, 41% of patients were free of AF at the end of the operation (20.5% SR, 20.5% PM). Despite antiarrhythmic therapy, only 15.2% were free of AF at discharge. During follow-up, 9.4, 9.4 and 7.6% remained in sinus rhythm, respectively (P=0.0001). The rhythm status of patients during follow-up are shown in Table 4. During follow-up between discharge and 12 months, no significant change was detected in AF rate for both groups (P=0.25, P=0.98). During Holter monitorisation, early postoperatively, a subgroup analysis of Group A patients revealed no difference in terms of sinus rhythm restoration between patients who received a left or biatrial Maze procedure even though the small number of biatrial procedures did not allow to reach a statistically significant conclusion. However, none of the patients undergoing a biatrial Maze procedure had postoperative atrial flutter while right atrial flutter was detected in two patients with the left sided Maze procedure (P=0.005). These patients were treated successfully with percutaneous techniques. Atrial transport function (LAT) was evaluated 12 months postoperatively using transthoracic echocardiography with Doppler analysis of mitral flow in 31 patients showing that 95% of patients had recovered LAT in Group A. Restoration and maintaining sinus rhythm was significantly lower in Group B at discharge and follow-up. One patient in Group A needed a permanent pacemaker implantation 1 month after the operation due to a third degree AV block (3%). At 12 months, the functional capacity of patients had improved in both groups (P=0.0001). There were no thromboembolic events detected in Group A. In Group B, there were two thromboembolic events, one resulting with death (6%, P=0.081) (Table 4).
|
|
4. Discussion |
|---|
|
TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
Significant mitral valve disease is often associated with chronic AF and approximately 60% of mitral valve cases referred for surgery are reported to have AF [14,15]. This fact has stimulated surgeons to approach these two problems during a combined minimally invasive approach. Mohr and associates have shown the feasibility of creating ablation lines using RF energy during minimally invasive valve procedures in a large series. They reported a 6 months and 1 year sinus rhythm restoration rate of 78 and 69%, respectively, in a group of 133 patients. This was a subset of 234 patients operated during a 3 years period showing the feasibility of RF ablation through a port access approach [16].
Dr Sie and Dr Khargi were among the first to use the irrigated RF device for the surgical treatment of AF [8,9]. Dr Sie reported a freedom from AF of 98 and 86%, at 1 and 2 years [17]. A recent review of the literature shows that 1 year sinus rhythm restoration varies between 62 and 98% among series using RF energy [4,11,12,18]. These differences can be attributed to variations in patient selection, ablation patterns and technical equipment used. The choice of lesion pattern during the ablation procedure differs among groups, thus having an implement over the success of the procedure [19]. A recent study has shown that a lesion pattern comprising of electrically isolating the pulmonary veins, left atrial appendage and left atrial connecting lesions was 100% effective in terminating AF in an animal model in comparison to other models which consist of pulmonary vein isolation alone [20]. This is similar to the ablation pattern the authors have been using. On the other hand, series based on simple pulmonary vein isolation seem to have a slightly lower SR restoration rate suggesting that simplifying the procedure comes at a cost of lower SR restoration rates [12,16,21]. One advantage of the left sided limited procedure is that it obviates the need for some incisions. However, if a patient develops atrial flutter after the operation, this usually needs to be managed by catheter ablation techniques [16,21]. Two patients in our series had to undergo such a procedure. These series report postoperative incidences of atrial flutter reaching 10–15% [16–22]. Although catheter based techniques can be applied in these patients, a second procedure will increase the cost considerably and this option may not be available in all centers. Our current policy is to apply a biatrial approach in patients with a history of atrial flutter or where the right atrium has to be opened. Otherwise, the procedure is limited to the left side. A combination of epicardial and endocardial ablation was applied during the right-sided Maze procedure. This is a modification of our previous method in order to avoid the amputation of the right atrial appendage and to reduce the number of surgical incisions [18]. However, the right sided procedure, especially ablation around the isthmus area slightly increases the risk of AV block, which happened in one patient in our series (3%).
Esophagus injury and coronary artery damage (circumflex artery) are two serious complications that have been reported during RF ablation [16,23]. Esophageal injury reported in most series is attributed to the heat waves transmitted by the TEE probe. Therefore, the removal of the probe before beginning the ablation is advised. In addition, the type of RF device, amount of energy delivered and the ablation pattern are other points that need to be mentioned in order to bring such complications to a minimum. The pulmonary vein is a thin structure which is in close relation to the esophagus and ablation inside the pulmonary veins may increase the chance of esophagus injury [16,21,23]. The authors lesion pattern largely replicates the Maze III procedure, with the ablation lines being located outside the pulmonary veins and never entering the vein, thus minimizing the chance of esophageal damage. The saline irrigation has some theoretical advantages over dry RF systems. It cools the surface temperature so that direct heating is transmitted below the surface resulting in a lesion of greater depth and higher chance of creating a transmural lesion. Irrigation obviates the need of firm contact and pressure. This also avoids the use of excessive energy levels that can cause collateral damage which has been reported in some series [16,23]. Probes designed to stamp at the tissue at a certain pressure with constant high energy levels bring the tissue, being ablated in closer relation to underlying structures, which can be a potential cause of collateral damage. The importance of probe design becomes even more crucial during minimally invasive procedures. The pen shaped probe used during this study enabled the surgeon to perform ablation lines through a limited incision allowing sufficient endothoracic movement without any pressure to the atrial tissue. However, in patients with a deep chest and giant atrium, it can be difficult to reach the LAA directly with the probe pen and a longer pen can be appreciated in such cases.
It has been postulated that many patients undergoing mitral valve surgery convert to sinus rhythm irrespective of ablation and that ablation may not be necessary in this group of patients. It has also been suggested that routine prophylactic use of antiarrhythmics might have a major role in the high conversion rates to sinus. However, these ideas do not seem to be justified by the data coming from this study since only 9% of patients who did not receive ablation were in sinus rhythm at 1 year despite antiarrhythmic therapy (P=0.0001). Several studies have shown similar results [9,24]. Whatever technique is used, even with the original Maze procedure, an early AF rate of 35% is reported [25]. This early AF is explained by the late healing process of atrial lesions and by the inflammatory process associated with the procedure. In addition, early atrial arrhythmias and AF after the operation can be caused by small macro re-entries which respond well to antiarrhythmic therapy [25]. We believe that these data provide a solid basis for such a therapy after the operation even though the prophylactic use of antiarrhythmics is still a controversial issue.
A major criticism for port access surgery has been the prolonged CPB and ischemic times. Our series is no exception. Even though CPB and cross-clamp time improved during the learning curve, they still exceeded the conventional method. Although the ischemic time was slightly longer in the RF Maze group, this did not have any adverse effect on outcome. However, both the port access technique and complex mitral valve repair require a learning curve and it is the authors feeling that complex mitral valve repair should be avoided in the beginning of one's experience during port access surgery.
Outcome after mitral valve surgery can be influenced by many factors. Studies have shown that persisting chronic AF has a negative impact, and these patients experience a reduced quality of life due to impaired hemodynamic function and increased risk of thromboembolism. Although the follow-up was short, none of the patients who received RF ablation had any thromboembolic event while two patients in Group B suffered from this complication (P=0.08). Longer term follow-up with larger series and other parameters are needed to reach any conclusion concerning the quality of life or the rate of thromboembolism between two groups. However, a recent study has shown that patients undergoing the Cox-Maze procedure enjoyed less thromboembolic complications at the end of 5 years, supporting the early data coming from our study [24].
Our series did not include any patient with lone AF. However, the avoidance of a sternotomy may largely increase patient acceptance of surgical treatment for isolated AF and can become a major reason for increased patient referral for antiarrhythmic surgical treatment. As for AF with structural valve disease, achieving both goals through a port access approach becomes even more important since many of the isolated mitral valve cases are operated through a minimally invasive approach today.
In conclusion, the port access approach provided a good access for both valve surgery and the RF Maze procedure. The combination of direct and videoscopic vision allowed adequate view of both the valve and left atrium, leading to a safe and efficient combined procedure. There were no procedure related complications such as esophagus or coronary artery injury. Short and intermediate term follow-up was favourable, with 93.6% of patients receiving the combined procedure being free of AF at 12 months in comparison to 9% in the control group. No thromboembolic event was observed in the RF Maze group. Whether these favourable results will continue during the long-term remains to be seen; nevertheless, early results are encouraging.
|
5. Limitations of the study |
|---|
|
TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
|
References |
|---|
|
TopAbstract1. Introduction2. Materials and methods3. Results4. Discussion5. Limitations of the...References |
|---|
., Van Praet F., Vanerman H. Minimally invasive video-assisted mitral valve surgery: our lessons after a 4 year experience. Ann Thorac Surg 2001;72(3):1050-1054.[CrossRef]
nar B., Saniso
lu ., Saba
E., Bayndr O. Inraoperative saline-irrigated radiofrequency modified maze procedure for atrial fibrillation. Ann Thorac Surg 2002;74:1301-1306.
This article has been cited by other articles:
|
|
 |
|
  J. Melo, T. Santiago, C. Aguiar, E. Berglin, M. Knaut, O. Alfieri, S. Benussi, H. Sie, M. Williams, F. Hornero, et al. Surgery for atrial fibrillation in patients with mitral valve disease: Results at five years from the International Registry of Atrial Fibrillation Surgery. J. Thorac. Cardiovasc. Surg., April 1, 2008; 135(4): 863 - 869. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. T. McElderry, D. C. McGiffin, V. J. Plumb, K. Nanthakumar, A. E. Epstein, T. Yamada, and G. N. Kay Proarrhythmic Aspects of Atrial Fibrillation Surgery: Mechanisms of Postoperative Macroreentrant Tachycardias Circulation, January 15, 2008; 117(2): 155 - 162. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 W. Wisser, G. Seebacher, T. Fleck, C. Aigner, C. Khazen, G. Stix, D. Hutschala, and E. Wolner Permanent Chronic Atrial Fibrillation: Is Pulmonary Vein Isolation Alone Enough? Ann. Thorac. Surg., October 1, 2007; 84(4): 1151 - 1157. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. D. Barnett and N. Ad Surgical ablation as treatment for the elimination of atrial fibrillation: A meta-analysis J. Thorac. Cardiovasc. Surg., May 1, 2006; 131(5): 1029 - 1035. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Akpinar, I. Sanisoglu, M. Guden, E. Sagbas, B. Caynak, and Z. Bayramoglu Combined Off-Pump Coronary Artery Bypass Grafting Surgery and Ablative Therapy for Atrial Fibrillation: Early and Mid-Term Results Ann. Thorac. Surg., April 1, 2006; 81(4): 1332 - 1337. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Akpinar, M. Guden, E. Sagbas, I. Sanisoglu, B. Caynak, and Z. Bayramoglu Robotic-Enhanced Totally Endoscopic Mitral Valve Repair and Ablative Therapy. Ann. Thorac. Surg., March 1, 2006; 81(3): 1095 - 1098. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. T. Reston and J. H. Shuhaiber Meta-analysis of clinical outcomes of maze-related surgical procedures for medically refractory atrial fibrillation Eur. J. Cardiothorac. Surg., November 1, 2005; 28(5): 724 - 730. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
