A new era in the surgical treatment of atrial fibrillation: the impact of ablation technology and lesion set on procedural efficacy

BACKGROUND/OBJECTIVE: While the Cox-Maze procedure remains the gold standard for the surgical treatment of atrial fibrillation (AF), the use of ablation technology has revolutionized the field. To simplify the procedure, our group has replaced most of the incisions with bipolar radiofrequency ablation lines. The purpose of this study was to examine results using bipolar radiofrequency in 130 patients undergoing a full Cox-Maze procedure, a limited Cox-Maze procedure, or pulmonary vein isolation alone. METHODS: A retrospective review was performed of patients who underwent a Cox-Maze procedure (n = 100), utilizing bipolar radiofrequency ablation, a limited Cox-Maze procedure (n = 7), or pulmonary vein isolation alone (n = 23). Follow-up was available on 129 of 130 patients (99%). RESULTS: Pulmonary vein isolation was confirmed by intraoperative pacing in all patients. Cross-clamp time in the lone Cox-Maze procedure patients was 44 +/- 21 minutes, and 104 +/- 42 minutes for the Cox-Maze procedure with a concomitant procedure, which was shortened considerably from our traditional cut-and-sew Cox-Maze procedure times (P < 0.05). There were 4 postoperative deaths in the Cox-Maze procedure group and 1 in the pulmonary vein isolation group. The mean follow-up was 13 +/- 10, 23 +/- 15, and 9 +/- 10 months for the Cox-Maze IV, the pulmonary vein isolation, and the limited Cox-Maze procedure groups, respectively. At last follow-up, freedom from AF was 90% (85 of 94), 86% (6 of 7), and 59% (10 of 17) in the in the Cox-Maze procedure group, limited Cox-Maze procedure group, and pulmonary vein isolation alone group, respectively. CONCLUSIONS: The use of bipolar radiofrequency ablation to replace Cox-Maze incisions was safe and effective at controlling AF. Pulmonary vein isolation alone was much less effective, and should be used cautiously in this population.     

Atrial fibrillation ablation during mitral valve surgery using the Atricure™ device

We have now used bipolar radiofrequency ablation in over 50 cases. A total of 43 patients have undergone a complete modified Cox-Maze procedure as described above; 19 had a lone Maze procedure, and 24 had a Maze procedure plus a concomitant operation. At 1 month postoperatively, high resolution MRI scans were performed in the first 8 patients to evaluate for pulmonary vein stenosis. All patients have been followed monthly since their operation by clinical examination and serial electrocardiograms.In our early experience with this procedure, there have been no operative mortalities. The cross-clamp time required to perform the modified bipolar radiofrequency ablation-assisted Maze procedure was 43 ± 26 minutes. This was significantly shorter than our experience with the cut-and-sew lone Cox-Maze procedure (93 ± 34 minutes; P < 0.05). Similarly, for concomitant procedures, our cross-clamp time was reduced from 122 ± 37 minutes to 92 ± 37 minutes (P < 0.05) when compared with the traditional cut-and-sew Maze procedure.The mean follow-up time in our series has been 7.4 ± 5.5 months. Follow-up MRI showed no evidence of pulmonary vein stenosis, and atrial contractility was preserved in all patients. There were no late strokes. At a 6-months follow-up, 91% of patients were in sinus rhythm. At last follow-up, 41 of 43 patients (95%) were free from atrial fibrillation. At a 6-month follow-up, only 10 patients were still on antiarrhythmic drugs.Our results show that bipolar radiofrequency ablation can replace the majority of incisions of the traditional cut-and-sew Maze procedure. This significantly decreases the amount of time to perform the procedure. The morbidity with this new procedure appears to be low, while still maintaining the efficacy of the traditional cut-and-sew Maze procedure. With this simplified operation, the Maze procedure can safely be added to all patients with AF coming to the operating room for correction of their valvular heart disease.     

The Cox maze III procedure for atrial fibrillation: long-term efficacy in patients undergoing lone versus concomitant procedures

BACKGROUND: For the last decade, the Cox maze III procedure has been available for the treatment of atrial fibrillation. It is unknown whether the operation has similar efficacy in patients with lone atrial fibrillation compared with that in patients with atrial fibrillation associated with coronary, valve, or congenital heart disease. This study examined the long-term outcome of patients who underwent this procedure either as a lone operation or as a concomitant procedure. METHODS: From 1988 to 2001, 198 patients underwent a Cox maze III procedure; 112 were lone operations, and 86 were concomitant procedures. Major complications included renal failure, reoperation for bleeding, mediastinitis, stroke, and balloon pump insertion. Follow-up was performed by means of mail and telephone questionnaires with both the patients and their cardiologists. All patients who had any history of arrhythmia or who were taking medication had their rhythm documented by means of electrocardiography. RESULTS: The lone operation group was significantly younger (51.3 +/- 10.5 vs 58.8 +/- 9.9 years) and had a higher male/female ratio (4:1 vs 2:1). There was no difference in operative mortality between groups (1.8% vs 1.2%). At a follow-up of 5.4 +/- 2.9 years, 96.6% (172/178) of all patients were free of atrial fibrillation. There was no difference between the lone operation and concomitant procedure groups (95.9% vs 97.5%). CONCLUSION: The Cox maze III procedure has equivalent operative risk and long-term efficacy in patients undergoing both lone operations and concomitant procedures. The Cox maze III procedure remains the standard against which alternative procedures for atrial fibrillation must be judged.     

Surgical treatment of atrial fibrillation: predictors of late recurrence

OBJECTIVE: The Cox maze procedure was introduced in 1987 for the treatment of atrial fibrillation. This study evaluated the predictors of late atrial fibrillation recurrence in 276 consecutive patients who underwent this procedure at our institution. METHODS: From 1987 through June 2003, 276 patients (79 female and 197 male patients; mean age, 55 +/- 11 years) underwent the Cox maze procedure. Thirty-three patients had Cox maze procedure I, 16 patients had Cox maze procedure II, and 197 patients had Cox maze procedure III. The last 30 patients underwent a modified procedure (Cox maze procedure IV) with bipolar radiofrequency ablation. There were 113 (41%) patients who had a concomitant operation, most commonly either a mitral valve procedure (19%) or coronary artery bypass grafting (20%). Data were analyzed by means of univariate analysis, with preoperative and perioperative variables used as covariates. Patient follow-up was conducted by means of questionnaire, physician examination, and electrocardiographic documentation. All patients had a minimum of 6 months of follow-up. RESULTS: Patient follow-up was achieved in 92.8% of cases, with a mean follow-up time of 5.8 +/- 3.6 years. Risk factors for late atrial fibrillation recurrence were duration of preoperative atrial fibrillation (P = .01) and Cox maze procedure version (P = .001). There was no difference in actuarial 10-year survival between the Cox maze procedure versions. CONCLUSION: The Cox maze procedure remains the gold standard for the treatment of atrial fibrillation and has excellent long-term efficacy. The most significant predictor of late recurrence was duration of preoperative atrial fibrillation, suggesting that earlier surgical intervention would further increase efficacy.     

Surgical treatment of atrial fibrillation with bipolar radiofrequency ablation: mid-term results in one hundred consecutive patients

AIM: The Cox-Maze procedure was introduced nearly two decades ago for the surgical treatment of atrial fibrillation (AF). Recently, our group has replaced most of the incisions of the Cox-Maze procedure with bipolar radiofrequency (RF) ablations (Cox-Maze IV procedure). The purpose of this study was to examine our midterm results with the Cox-Maze procedure using bipolar RF ablation. METHODS: From January 2002 to October 2005, 100 consecutive patients underwent a modified Cox-Maze procedure with bipolar RF ablation for AF; 32 were lone operations, and 68 were concomitant procedures. Follow-up was performed at 1, 3, 6, and 12 months, and then annually thereafter. Heart rhythm was confirmed by electrocardiography. RESULTS: The mean age of patients was 62+/-13 years; 57% were male. Duration of AF was 6.3+/-7.6 years (0.1 to 40 years), 59% had paroxysmal AF, and 34% had permanent AF. Follow-up was complete for all patients with a mean follow-up of 13+/-10 months. At 12-month follow-up, 91% (49/54) of patients were free of AF. Cross-clamp time in the lone Cox-Maze IV procedure patients was 42+/-15 minutes, while it was 101+/-29 minutes for the Cox-Maze IV with a concomitant procedure (compared to 93+/-34 minutes and 122+/-37 minutes for the traditional procedure, P<0.05). There were four operative deaths. CONCLUSIONS: The Cox-Maze IV procedure had good mid-term efficacy. The use of bipolar RF energy significantly decreased operative time and simplified the procedure compared to the traditional Cox-Maze procedure, potentially increasing utilization of the procedure among cardiac surgeons.     

Evaluation of clinical treatment of atrial fibrillation associated with rheumatic mitral valve disease by radiofrequency ablation.

OBJECTIVES: The aim of this clinical study was to evaluate the effectiveness and advantages of the radiofrequency ablation maze procedure in the treatment of atrial fibrillation associated with rheumatic mitral valve disease. METHODS: We developed one kind of modified Cox III maze procedure with the use of radiofrequency ablation in the treatment of atrial fibrillation associated with rheumatic mitral valve disease and compared the outcome of 96 patients of atrial fibrillation associated rheumatic mitral valve disease who underwent radiofrequency ablation maze procedure plus mitral valve replacement with that of 87 patients with atrial fibrillation associated rheumatic mitral valve disease who had mitral valve replacement during the same interval by the same surgeon. The patients in the two groups were similar in age, gender, preoperative New York Heart Association class and duration of preoperative atrial fibrillation. RESULTS: No operative deaths occurred in the study group and the control group. Duration of cardiopulmonary bypass (137.63 +/- 10.82 vs. 90.95 +/- 7.65 min, P<0.01) and duration of aortic crossclamping (56.96 +/- 6.19 vs. 32.66 +/- 3.55 min, P<0.01) were prolonged in the study group. Blood loss from chest tubes was similar in the two groups (494.06 +/- 100.44 vs. 476.09 +/- 115.84 ml, P=0.263). Freedom from atrial fibrillation in the study group was 77% 3 years after the operation compared with 25% in the control group (P<0.01). CONCLUSIONS: The addition of the radiofrequency ablation maze procedure to mitral valve replacement is safe and effective in the treatment of atrial fibrillation associated with rheumatic mitral valve disease.     

二尖瓣置换术中射频消融治疗慢性心房颤动的疗效分析

目的 分析二尖瓣置换术同期采用Atricure双极射频改良迷宫手术治疗慢性心房颤动的疗效,总结其临床经验。 方法 回顾性分析2010年6月至2012年9月苏北人民医院59例二尖瓣病变合并慢性心房颤动患者的临床资料,其中男22例,女37例;年龄29 ～ 71 （48 ± 11） 岁。心房颤动持续时间1.2 ～ 26.0 （7.2 ± 3.4） 年。术前心功能（NYHA分级） Ⅱ级20例,Ⅲ级31例,Ⅳ级8例。二尖瓣中至重度狭窄32例,二尖瓣中至重度关闭不全9例,二尖瓣狭窄伴关闭不全18例;合并三尖瓣关闭不全42例。左心房内径39 ～ 98 （55.2±8.9） mm。9例患者左心房内有血栓形成。于术中应用Atricure双极射频消融装置（Inc.West Chester,Ohio,USA）,频率460 kHz,最大能量28.5 W,在常温体外循环心脏跳动下进行右心房消融,然后在中低温心脏停搏下进行左、右肺静脉口和左心房的消融隔离,最后进行二尖瓣置换。术后常规使用胺碘酮,并定期进行随访。 结果 术后无围术期死亡,体外循环时间 65～180 （99 ± 28） min, 主动脉阻断时间 46～123 （69 ± 17） min,射频消融时间15～28 （21 ± 4） min。术后心脏复跳后44例患者立即恢复窦性心律,10例患者仍为心房颤动,1例患者呈心房扑动心律,4例患者心动过缓使用心外膜临时起搏（3例恢复窦性心律,1例仍为心房颤动）。术后随访58例,随访时间6～33个月,失访1例。出院时、术后3个月、6个月、1年和2年窦性心律转复率分别为86.2 % （50/58）、91.4% （53/58）、89.7 % （52/58）、84.6 % （33/39）和71.4 % （5/7）。随访期间无远期血栓栓塞发生。 结论 二尖瓣置换术中应用Atricure双极射频改良迷宫手术治疗慢性心房颤动安全、近期疗效良好。     

Long-term results of irrigated radiofrequency modified maze procedure in 200 patients with concomitant cardiac surgery: six years experience

BACKGROUND: The Cox maze procedure is considered an effective surgical treatment of atrial fibrillation in patients with and without organic heart disease. Radiofrequency energy offers an alternative to the complex surgical maze procedure. We used the radiofrequency modified maze III procedure in patients with atrial fibrillation undergoing elective concomitant cardiac surgery. This study evaluated the long-term results of the irrigated radiofrequency ablation to create linear lines of conduction block endocardially. METHODS: Between November 1995 and June 2001, 200 patients with mainly structural heart disease and chronic atrial fibrillation underwent intraoperative radiofrequency linear ablation in both atria with concomitant cardiac surgery. RESULTS: The in-hospital mortality rate was 3.5% (7 patients) and during the mean follow-up of 40 months (range, 12 to 80) 27 patients (13.5%) died. Eight patients (4%) were lost from follow-up and complete data were available in 158 survivors. Sinus or atrial rhythm was present in 116 patients (73.4%) and an atrial driven rhythm in 10 patients (6.3%) with an atrioventricular pacemaker. Atrial fibrillation or flutter was documented in 32 patients (20.3%). Antiarrhythmic drugs were used in 49% of survivors who were free of atrial fibrillation or flutter. CONCLUSIONS: Intraoperative radiofrequency endocardial ablation is an effective technique to eliminate atrial fibrillation with promising long-term results.     

Atrial reduction plasty Cox maze procedure: extended indications for atrial fibrillation surgery

BACKGROUND: The Cox maze procedure yields good results for atrial fibrillation (AF). However, patients with predictors of failure-chronic long-standing AF, low amplitude fibrillatory waves, and large left atriums-are generally thought not to benefit from a maze procedure. We report an aggressive approach for these patients, utilizing biatrial reduction plasty concomitantly with the Cox maze procedure for AF. METHODS: A complete Cox maze procedure utilizing supplemental RF ablation was performed in 36 patients. All underwent resection of both atrial appendages and biatrial reduction plasty encompassing resection of the left atrial posterior wall from left to right pulmonary veins and from inferior pulmonary veins to the mitral annulus, as well as removal of the right atrial lateral wall. Mitral or tricuspid valve repair, or both, was performed on 32 patients. RESULTS: These patients had a mean AF duration of 45 +/- 89 months. Their preoperative left atria measured 66 +/- 16 mm, with mean AF waves of 0.74 +/- 0.3 mm. Mean preoperative New York Heart Association class was 2.7 +/- 0.7 and left ventricular ejection fraction was 48 +/- 9. Cross clamp and bypass times were 91 +/- 35 minutes and 124 +/- 33 minutes, respectively. The average posterior left atrial tissue resected was 5.4 x 2.1 cm, and mean resected atrial weight was 10.3 +/- 2 g. There were no deaths and length of stay was 5.5 +/- 2 days. At a follow-up time of 19 +/- 16 months, 32 of the 36 patients were in normal sinus rhythm and New York Heart Association class I. CONCLUSIONS: Aggressive biatrial reduction plasty Cox maze procedure was effective in 89% of these "low success" AF patients. This simple procedure can extend utilization of the Cox maze procedure to more patients with chronic AF.     

Radiofrequency modified maze in patients with atrial fibrillation undergoing concomitant cardiac surgery

OBJECTIVE: In the majority of patients with chronic atrial fibrillation the arrhythmia will persist after correction of the underlying structural abnormality. The maze procedure is an effective surgical method to eliminate atrial fibrillation and to restore atrial contractility. METHODS: In this study we used radiofrequency energy to create lines of conduction block in both atria during cardiac surgery as a modification of the maze III procedure. One hundred twenty-two patients with atrial fibrillation for at least 1 year and structural heart disease underwent open heart operation and a radiofrequency modified maze procedure. RESULTS: In 108 (89%) of 122 patients mitral valve surgery was performed, and in this group 86 patients (80%) underwent 121 concomitant procedures. Fourteen patients (11%) underwent cardiac surgery not involving the mitral valve. The additional crossclamp time required for the left atrial part of the radiofrequency modified maze procedure was 14 +/- 3 minutes. The in-hospital mortality rate was 4.1%. The overall 39-month survival was 90%, and freedom of atrial flutter or atrial fibrillation was 78.5% +/- 5.1%. Eighty-nine survivors with sinus, atrial rhythm, or atrioventricular sequential pacemaker had Doppler echocardiography, and right atrial transport function was documented in 83% and left atrial transport function in 77% of patients. CONCLUSION: We concluded that the radiofrequency modified maze procedure as an adjunctive procedure is safe, time-sparing, and effective in eliminating atrial fibrillation and restoring atrial transport function.     

Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study

BACKGROUND: Alternative energy sources have been proposed for the transvenous and surgical treatment of atrial fibrillation. This study examined the physiologic consequences of a novel energy source, bipolar radiofrequency energy, in a chronic animal model in order to determine its ability to produce transmural lesions on the beating heart. METHODS: Five dogs underwent baseline pacing from the following target areas: right and left atrial appendage, superior and inferior vena cavae, and right and left pulmonary veins. A cuff of atrial myocardium, proximal to the target tissue was clamped and ablated between the arms of the bipolar radiofrequency energy device. Tissue conductance was used as a transmural indicator. After ablation, the pacing protocol was repeated. Baseline and postablation pulmonary vein flows were measured. Animals were survived for 30 days, and permanent electrical isolation was evaluated by pacing, epicardial mapping, and histology. RESULTS: Mean ablation time was 5.0 +/- 1.8 seconds and mean peak tissue temperature was 46.7 degrees C +/- 2.8 degrees C. All lesions (30/30) acutely and permanently isolated atrial tissue. There was no change in pulmonary vein flow. Mapping studies with pacing of atrial tissue on both sides of the lesion confirmed isolation. Histology demonstrated that all lesions were linear, continuous, and transmural with no thrombus formation or stenosis. CONCLUSIONS: Bipolar radiofrequency energy rapidly produced permanent transmural linear lesions on the beating heart. Measurement of tissue conductance reliably predicted transmural lesions. This new technology may enable the development of a less invasive, surgical approach to atrial fibrillation.     

The radiofrequency modified maze procedure. A less invasive surgical approach to atrial fibrillation during open-heart surgery.

OBJECTIVE: Patients with mitral valve disease and suffering of atrial fibrillation of more than 1 year's duration have a low probability of remaining in sinus rhythm after valve surgery alone. Intraoperative radiofrequency ablation was used as an alternative to simplify the surgical maze procedure. METHODS: Seventy-two patients with mitral valve disease, aged 63+/-11 years ranging from 31 to 80 years, underwent valve surgery and radiofrequency energy applied endocardially, based on the maze III procedure to eliminate the arrhythmia. The right-sided maze was performed on the beating heart and the left-sided maze during aorta cross-clamping. RESULTS: Surgical procedures included mitral valve repair (n=38) or replacement (n=34) and in addition tricuspid valve repair (n=42), closure of an atrial septal defect (n=2) and correction of cor triatriatum (n=1). The left-sided maze needed 14+/-3 min extra ischemic time. There were two in-hospital deaths (2.7%) and three patients (4.2%) died during follow-up of 20+/-15 months. Among 67 surviving patients, 51 patients (76%) were in sinus rhythm, two patients (3%) had an atrial rhythm and eight patients (12%) had persistent atrial fibrillation or atrial flutter. Four patients had a pacemaker implanted, in one patient because of sinus node dysfunction. Doppler echocardiography in 64 patients demonstrated right atrial contractility in 89% and left atrial transport in 91% of patients. CONCLUSIONS: Intraoperative radiofrequency ablation of atrial fibrillation is an effective and less invasive alternative for the original maze procedure to eliminate atrial fibrillation.     

Prevention of atrial fibrillation during the acute postoperative period following open-heart surgery by pulmonary vein antrum isolation using bipolar radiofrequency ablation

We evaluated the effectiveness of pulmonary vein isolation (PVI) with bipolar radiofrequency ablation in prevention of atrial fibrillation during the acute postoperative period following open-heart surgery. Twenty-six patients with paroxysmal atrial fibrillation (PAF) underwent elective open-heart surgery combined with PVI using bipolar radiofrequency ablation from October 2004 to January 2006. They consisted of 17 male and 9 female with the mean age of 64.2 +/- 8.6 years. Their structural heart disease included coronary artery disease, aortic valve disease, and mitral valve disease. PVI was performed on the bilateral pulmonary vein antra under beating heart using cardiopulmonary bypass. The bipolar radiofrequency system included Atricure (n = 19) and Cardioblate (n = 7). There was no operative death nor complication related to bipolar radiofrequency ablation. In principle, no anti-arrhythmic drugs except beta-blockades were administered postoperatively. In 24 of 26 (92.3%) patients, the sinus rhythms were restored without PAF during the 2 week postoperative period. Even in cases with preoperative PAF, PVI was effective in preventing atrial fibrillation during the acute phase following open-heart surgery. We suggest that bipolar radiofrequency ablation is an alternative procedure to prevent atrial fibrillation in open-heart surgery.     

The long-term outcome of patients with coronary disease and atrial fibrillation undergoing the Cox maze procedure

BACKGROUND: A significant number of patients presenting for coronary revascularization have chronic atrial fibrillation. Although the Cox maze III procedure is the gold standard for the surgical treatment of this arrhythmia, few of these patients undergo atrial fibrillation operations at the time of their coronary bypass grafting. This study examined the long-term outcome of patients with ischemic heart disease who underwent the Cox maze procedure at our institution. METHODS: From 1990 to 2002, 47 patients undergoing operations for ischemic heart disease underwent a concomitant Cox maze III procedure. All patients underwent coronary bypass grafting, and 7 (15%) patients underwent coronary bypass grafting plus a mitral valve repair. Follow-up was performed by means of mail and telephone questionnaires with both the patients and their cardiologists. All patients who had any history of arrhythmia or who were taking medications had their rhythm documented by electrocardiogram. RESULTS: The mean age of these patients was 62 +/- 8 years, with a marked male predominance (45 men and 2 women). Twenty-eight (60%) of the patients had paroxysmal atrial fibrillation, and the remainder had persistent arrhythmias. The mean duration of atrial fibrillation was 7.6 +/- 6.5 years. The operative mortality in this series was 2%. Nine (19%) patients required postoperative pacemakers. At last follow-up (mean of 5.7 +/- 3.3 years), 98% of patients were free of atrial fibrillation. CONCLUSION: The Cox maze III procedure has a low operative mortality and excellent long-term efficacy in patients with ischemic heart disease. These data suggest a more widespread use of this procedure in these patients.     

Outcome of valve repair and the Cox maze procedure for mitral regurgitation and associated atrial fibrillation.

OBJECTIVE: The objective was to determine whether the Cox maze procedure provides adjunctive benefit in patients with atrial fibrillation undergoing mitral valve repair. METHODS: We compared the outcome of 39 patients who had the Cox maze procedure plus mitral valve repair between January 1993 and December 1996 (maze group) with that of 58 patients with preoperative atrial fibrillation who had mitral valve repair during the same interval by the same surgeons (control group). Patients in the 2 cohorts were similar for age, gender, preoperative New York Heart Association class III or IV, and duration of preoperative atrial fibrillation. The control group had a higher incidence of previous heart surgery and coronary artery disease. RESULTS: No operative deaths occurred, and 1 patient in each group required pacemaker implantation after the operation. Duration of cardiopulmonary bypass (122 +/- 40 minutes vs 58 +/- 27 minutes, P <.0001) and hospitalization (12.6 +/- 6.4 vs 9.3 +/- 3.4 days, P <.0025) were prolonged in patients having the Cox maze procedure. Overall, 2-year survival was similar (92% +/- 5% for maze patients and 96% +/- 3% for controls). Freedom from atrial fibrillation in the maze group was 74% +/- 8% 2 years after the operation compared with 27% +/- 7% for the control group (P <.0001). Freedom from stroke or anticoagulant-associated bleeding in the maze group was 100% 2 years after the operation compared with 90% +/- 8% in the control group (P =.04). At most recent follow-up, 82% of maze patients were in normal sinus rhythm (53% in control group). CONCLUSION: The addition of the Cox maze procedure to mitral valve repair is safe and effective for selected patients, and elimination of atrial fibrillation decreased late complications.     

Lateral placement of bipolar clamp facilitates pulmonary vein isolation

The surgical management of atrial fibrillation is becoming more commonplace with the procedure of pulmonary vein isolation forming the cornerstone of the treatment of atrial fibrillation. In this article a technique is described to introduce a dry bipolar radiofrequency clamp into the chest through a lateral port sized incision to safely effect pulmonary vein isolation in patients with low ejection fractions undergoing a concomitant mini-maze procedure. Confirmation of the transmurality and effectiveness of the lines of ablation is shown by the demonstration of bidirectional block to and from the pulmonary veins.     

Medium-term outcome of different surgical methods to cure atrial fibrillation: is less worse?

Different lesion sets and ablation techniques have been performed. We compared these outcomes in search of the best method. We performed a retrospective analysis of patients who have undergone AF surgery different from the maze III. The surgical lesion sets were pulmonary vein isolation (PVI) alone, left atrial maze (LAM) and bi-atrial maze (BAM) and were made with different ablation techniques. During surgery one patient died due to bleeding of a pulmonary vein. The number of patients in the PVI-, LAM-, BAM-groups was 12, 28 and 26, respectively, with freedom from AF at latest follow-up [22.0+/-15.6 (3.1-81.2) months] of 33%, 59% and 60%, respectively. Atrial flutter occurred less in the BAM-group (4%) than in the left-sided procedures (15.4%) (P=0.231). Multivariate analysis demonstrated a higher recurrence of AF for PVI alone (OR 4.42, CL 0.95-20.6, P=0.0583) and a lower recurrence for the 'cut-and-sew' technique (OR 0.13, CL 0.030-0.60, P=0.0084). Left- and bi-atrial maze procedures are equally effective in the suppression of AF, whereas omission of right-sided lesions results in a higher prevalence of atrial flutter. The 'cut-and-sew' technique is superior in terms of freedom from AF compared to bipolar and unipolar radiofrequency.     

Kleine Schnitte – große Wirkung

The Cox-MAZE procedure and less complex modifications with alternative energy sources have gained widespread use as a treatment modality for patients with concomitant atrial fibrillation. Endocardial ablation is easy to perform and effective. Epicardial techniques may even simplify the procedure by allowing surgery on a beating heart. The development of new ablation devices using uni- or bipolar radiofrequency or focused ultrasound energy makes it possible to perform an endoscopic ablation by creating transmural lesions on a beating heart without cardiopulmonary bypass. This gentle procedure has a higher success rate in achieving sinus rhythm than catheter ablation especially in patients with persistent atrial fibrillation and is therefore a good alternative for patients with “lone atrial fibrillation”. Therefore, to be prepared for the future, heart surgeons should be trained in endoscopic procedures due to the potential of minimally invasive techniques.     

Recent topics on the surgical treatment for atrial fibrillation.

After the introduction of endocardial radiofrequency catheter, only two arrhythmias, atrial fibrillation and ischemic ventricular tachycardia require surgical procedures. In this review, we describe recent advancements and problems of surgical treatment for atrial fibrillation. On the basis of multiple-circuit re-entry theory, Cox developed the maze operation with the aim of interrupting the re-entry circuit. Although this procedure has become the gold standard technique for the surgical treatment of atrial fibrillation with approximately 90% success rate, several modifications have been made over time. To obtain a more physiological atrial transport function, radial approach technique or bilateral appendage-preserved maze procedures were developed and to simplify surgical procedures, maze operation with cryo-ablation or radiofrequency-ablation were created. Other topics are concerned with surgical target or approach to atrial fibrillation. Ectopic focus theories from pulmonary veins have been widely recognized recently and the surgical isolation of pulmonary veins orifices is performed with various energy sources. In addition to standard cut-and-sew surgical technique, cryoablation, unipolar or bipolar radiofrequency ablation, or microwave ablation were induced with endocardial or epicardial approach for the achievement of less invasive cardiac surgery. As atrial fibrillation leads to frequent mortality, cardiac surgeons have to treat atrial fibrillation with other cardiac disease more frequently to obtain better quality of operative results.     

Chronic transmural atrial ablation by using bipolar radiofrequency energy on the beating heart

BACKGROUND: Recently, there has been renewed interest in the development of minimally invasive procedures to treat atrial fibrillation. Unipolar radiofrequency catheters are plagued by poor results, in part because of their inability to produce transmural lesions. This study tested the ability of bipolar radiofrequency energy to create chronic transmural lesions on the beating heart that isolated atrial myocardium. METHODS: Five sheep underwent a right thoracotomy. Baseline pacing was performed from the following targeted areas: right atrial appendage, superior vena cava, inferior vena cava, and right pulmonary veins. A cuff of atrial myocardium around the targeted tissue was clamped between the 2 arms of the device. Radiofrequency energy was delivered at 750 mA and continued until the tissue conductance between the electrodes reached a stable minimum level. After ablation, pacing was used to document tissue isolation. The animals survived for 30 days. RESULTS: Twenty circumferential lesions were produced at the initial operation. The mean ablation time was 9.3 +/- 4.0 seconds, and the mean peak temperature was 48.4 degrees C +/- 6.4 degrees C. All lesions acutely and chronically isolated the targeted tissue. Trichrome staining showed that all lesions were transmural. There were no instances of pulmonary vein stenosis or thrombosis. CONCLUSIONS: Bipolar radiofrequency energy can produce permanent transmural linear lesions on the beating heart. Online measurement of tissue conductance reliably predicted lesion transmurality. This new technology may enable surgeons to perform a curative minimally invasive operation for atrial fibrillation on the beating heart.