Radiofrequency and cryoablation of atrial fibrillation in patients undergoing valvular operations

Comparison of Radiofrequency Ablation and Cryoablation for the Recovery of Atrial Contractility and Survival

Background

Limited comparative data are available on the efficacy of cryoablation versus radiofrequency ablation in patients with atrial fibrillation. This study aimed to compare radiofrequency ablation and cryoablation with regard to clinical outcomes and the restoration of sinus rhythm or atrial contractility.

Methods

A total of 239 patients who underwent surgical ablation between August 2003 and December 2016 at our institution were included. The patients were divided into 2 groups according to the energy device that was used (group A: n=140, radiofrequency ablator; group B: n=99, cryoablator). Echocardiographic data, overall survival, and major cardiovascular and cerebrovascular event (MACCE)-free survival were compared between the 2 groups.

Results

At 1 year of follow-up, the atrial contractility recovery rate was 32.2% (19 of 59) in group A and 48.8% (21 of 44) in group B. In addition, cryoablation was found to be a predictive factor for the recovery of atrial contractility (cryoablation vs. radiofrequency ablation: odds ratio, 2.540; 95% confidence interval, 1.063–6.071; p=0.036). The left ventricular ejection fraction was significantly higher in group B (53.1%±11.5% vs. 59.1%±6.3%, p=0.001). The median follow-up duration was 36 months. The 5-year overall survival rate was 80.1%±3.6% in group A and 92.1%±2.9% in group B (p=0.400). The 5-year MACCE-free survival rate was 70.3%±4.0% in group A and 70.9%±5.6% in group B (p=0.818).

Conclusion

Cryoablation was associated with a higher atrial contractility restoration rate and better left ventricular function than radiofrequency ablation. However, no significant relationship was observed between the energy source and overall or MACCE-free survival.

Rhythmic and haemodynamic determinants of long-term survival after radiofrequency ablation of atrial fibrillation in mitral valve surgery

Aims

The aim of the present study was to evaluate the effects of sinus rhythm recovery on long-term survival after radiofrequency (RF) ablation in patients with permanent atrial fibrillation (AF) undergoing surgery for mitral valve disease.

Methods and results

This study included 173 consecutive patients (101 men and 72 women, age 67 ± 9 years) with AF and mitral valve disease who underwent RF ablation procedure associated with mitral valve surgery. Four patients died during hospitalization. At the 6-year follow-up, sinus rhythm was present in 68% of the surviving patients. Thirty-nine patients remained in persistent AF after hospital discharge. In patients with stable sinus rhythm, mortality (10 vs. 30%) and recurrent hospitalization were significantly lower than in patients with persistent AF, but functional capacity improved. The incidence of stroke was also lower in patients with stable sinus rhythm. A pre-operative higher right and left atrial area, pulmonary hypertension, and rheumatic disease were associated with the persistence of AF despite RF ablation. At multivariate analysis, only age and concomitant tricuspid valve repair were independently associated with mortality, whereas the right atria area and tricuspid valve repair were associated with persistent AF.

Conclusion

Although the re-establishment of sinus rhythm by unipolar RF ablation is associated with a higher survival rate after mitral valve surgery, our data suggest that a more severe haemodynamic impairment, in particular in patients with rheumatic valve disease, may be responsible both for higher long-term mortality and lower rate of sinus rate maintenance.

Sinus Rhythm Restoration after Radiofrequency Ablation Improves Survival in Patients Undergoing Mitral Valve Surgery : A Eight Year Single Center Study

Background

The usefulness of radiofrequency (RF) ablation in restoring sinus rhythm in patients with permanent atrial fibrillation (AF) undergoing surgery for mitral valve has been demonstrated. But whether sinus rhythm recovery affects long-term survival is less clear.

Methods

This study included 301 consecutive patients (126 men and 175 women, age 69±6 years) undergoing radiofrequency ablation of persistent atrial fibrillation along with mitral valve surgery. Radiofrequency ablation was performed using unipolar probe in 55.3%, bipolar probe in the remaining 44.7% of cases.

Results

Four patients died during hospitalization. At follow-up, sinus rhythm was present in 76% of the surviving patients. 71 patients never recovered sinus rhythm after hospital discharge. Mortality and recurrent hospitalization were significantly lower in patients with sinus rhythm at the end of follow-up in comparison to permanent AF. The incidence of stroke was also lower in patients with stable sinus rhythm. Larger atria, pulmonary hypertension and history of rheumatic disease were associated with the persistence of AF despite radiofrequency ablation. Although survival and functional capacity were significantly lower in patients with permanent AF at multivariate analysis only age and pulmonary artery pressure before surgery were independently associated with mortality.

Conclusion

Sinus rhythm restoration by RF ablation in patients undergoing mitral valve surgery is associated with an improved long-term survival. However our results suggest that a more severe hemodynamic impairment, expressed by higher pulmonary artery pressure, and increasing age are the only independent factors related to long-term survival.

Long-term results of radiofrequency maze procedure for persistent atrial fibrillation with concomitant mitral surgery

Background

The radiofrequency (RF) maze procedure can effectively restore sinus rhythm in most patients with persistent atrial fibrillation (AF) and mitral disease. However, long-term results and predictors for late AF recurrence are still under investigation.

Methods

From December 1995 to November 2011, 207 consecutive patients with persistent AF and mitral disease underwent RF maze procedure and concomitant mitral surgery. The mean age was 54±12.4 year-old. Mitral surgery was performed in all patients and concomitant procedures including tricuspid surgery, aortic valve surgery, and atrial septal defect closure were carried on 164 patients.

Results

The in-hospital mortality was 3.9% (n=8) and late mortality was 8.2% (n=17). After a mean follow-up period of 101±50.9 months, 154 patients (74.4%) had long-term sinus conversion. A permanent pacer was implanted in 8 patients (3.9%). By Cox multivariate survival regression analysis, predictors for long-term sinus conversion were identified to be the duration of persistent AF, preoperative left atrial (LA) diameter, preoperative right atrial (RA) area, and preoperative beta-blocker use. The receiver operating characteristic (ROC) curve analysis showed that the best cutoff value for persistent AF duration, preoperative LA diameter, and preoperative RA area were 59.5 months, 59.85 mm, and 25.65 cm².

Conclusions

Longer persistent AF duration, larger preoperative LA diameter, larger preoperative RA area and preoperative beta-blocker use were the predictors for negative long-term outcome of RF maze procedure for the patients with persistent AF underwent concomitant mitral surgery. Timely referral of patients for surgery is mandatory.

Intraoperative Cryoablation of Atrial Fibrillation With the Old-Fashioned Cryode Tips: A Simple, Effective, and Inexpensive Method

Nowadays atrial fibrillation is usually treated simultaneously with cardiac procedures, and new cryo-systems have been developed for performing easier and faster intraoperative ablation. However, the old cryode designs can still be useful in surgical practice and represent a more cost-effective method. In this article we present a technique using old-fashioned cryodes for intraoperative treatment of atrial fibrillation and comment on its advantages and limitations.

Surgical treatment of atrial fibrillation : a systematic review

BACKGROUND

The recently published overwhelming number of publications on the surgical treatment of AF, using a wide variety of techniques, blurred any precise appreciation of the nowadays surgical treatment of AF. As a consequence, the "state of the art" of the surgical technique of AF is ill-defined.

OBJECTIVES

In this review the efficacy of the alternative sources of energy (radiofrequency-microwave and cryoablation; (group I) and the classical "cut and sew" Cox-Maze III (group II), which claims a 97-99% sinus rhythm (SR) success rate, were evaluated in the surgical treatment of atrial fibrillation (AF).

METHODS

A computerized search in the PubMed and Medline database was conducted. Only original, English written, clinical manuscripts on the surgical treatment of atrial fibrillation citing the clinical outcome, including the postoperative sinus rhythm, were included. The following data were registered: the absolute numbers and percentages of treated patients, gender (male versus female) distribution, the type of arrhythmia (permanent or paroxysmal AF), type of surgery (mitral or non-mitral valve or a lone AF surgical procedure), postoperative morbidity (bleeding, the use of an intra-aortic balloon pump, cerebral vascular accident), postoperative pacemaker implantations, 30-day mortality, survival and sinus rhythm conversion. The mean values for age (years), left atrial diameter (mm), preoperative duration of AF (years) and left ventricular ejection fraction (%) were also recorded.

RESULTS

Forty-eight studies were included comprising 3832 patients: 2279 in group I and 1553 in group II. The mean duration of AF, left atrial diameter and LVEF were 5.4 versus 5.5 years (p=0.90), 55.5 versus 57.8 mm (p=0.23) and 57 versus 58% (p=0.63). The postoperative SR rates for group I and II were 78.3 versus 84.9% (p=0.03). However, the "cut and sew" Cox-Maze III was conducted in younger patients (55.0 versus 61.2 years; p=0.005), more often to treat paroxysmal (22.9 versus 8.0%) and lone AF (19.3 versus 1.6%). Alternative sources of energy were predominantly used to treat permanent AF (92.0%), almost always as a concomitant surgical procedure (98.4%) and increasingly in combination with non-mitral valve surgery (18.5%). After correction for these variations, the postoperative SR conversion rates for group I and II did not differ significantly anymore.

CONCLUSIONS

We could not identify any significant difference in the postoperative SR conversion rates between the classical 'cut and sew' and the alternative sources of energy, which were used to treat atrial fibrillation.

Guidelines for reporting data and outcomes for the surgical treatment of atrial fibrillation

Atrial fibrillation is the most common sustained cardiac rhythm disturbance, affecting an estimated 2.5 million people in the United States. Atrial fibrillation may occur with or without structural heart disease. The medical and surgical literature has seen an exponential growth in reports of ablation techniques and the Cox-Maze procedure to treat atrial fibrillation. There has been no agreement or standards on the proper reporting of these techniques and results. The current literature is in disarray, and this report is an attempt to provide a framework for the necessary elements to be included in reports on this subject. The Workforce on Evidence Based Surgery of the Society of Thoracic Surgeons encourages the adoption of these guidelines for reporting clinical results derived from patients undergoing surgical procedures for atrial fibrillation. Adoption of these guidelines will greatly facilitate the comparison between the reported experiences of various authors treating different cohorts of patients at different times with different techniques and energy sources. These guidelines are also appropriate for catheter-based treatment of atrial fibrillation. Thus, more reliable evaluation and comparisons of results will advance our knowledge and further the development and application of these procedures.

Superiority of cut-and-sew technique for the Cox maze procedure: comparison with radiofrequency ablation

OBJECTIVE

Although radiofrequency ablation is increasingly used to create the atrial lesions of the Cox maze procedure, its effectiveness in ablating atrial fibrillation compared with the standard cut-and-sew method is not known. We compare the freedom from atrial fibrillation in patients undergoing both methods with identical lesion sets.

METHODS

Radiofrequency ablation was used to create full Cox maze lesions in 56 patients between January 2002 and February 2005; these patients were matched with those who underwent the standard cut-and-sew method. Matched variables were gender (33 male, 23 female, both), age (67.5 vs 67.2 years), New York Heart Association class (mean 2.28 vs 1.96), atrial fibrillation type (37 paroxysmal, 19 continuous, both), and concomitant mitral valve surgery (37 in both). Hypertension, preoperative left atrial size, and preoperative duration of atrial fibrillation were similar between groups.

RESULTS

When compared with matched controls, fewer patients undergoing radiofrequency ablation were free from atrial fibrillation at dismissal (63% vs 88%; P = .0039) and at last follow-up (62% vs 92%; P = .016). According to logistic regression for matched pairs, patients undergoing radiofrequency ablation were 4.5 times more likely to be in atrial fibrillation at dismissal (95% confidence intervals [CI], 1.8, 10.9) and 5 times more likely to be in atrial fibrillation at follow-up (95% CI, 1.4, 17.3). No other covariate was associated with atrial fibrillation status at hospital dismissal or follow-up.

CONCLUSION

Creating Cox maze lesions with radiofrequency ablation is associated with less freedom from atrial fibrillation both early and late postoperatively. Because transmurality can be assured, the standard cut-and-sew Cox maze procedure remains the gold standard for the surgical treatment of atrial fibrillation.

A novel atrial volume reduction technique to enhance the Cox maze procedure: Initial results

OBJECTIVE

Large left atrial diameter is reported to be a predictor for recurrent atrial fibrillation after the Cox maze procedure, and left atrial diameter by itself influences the chance of sinus rhythm recovery, as well as maintenance of sinus rhythm. However, additional cut-and-sew procedures to decrease left atrial diameter extend operative time and can cause bleeding. Thus we developed a no-bleeding, faster, and therefore less invasive left atrial volume reduction technique to enhance the Cox maze procedure.

METHODS

The modified Cox maze III procedure with cryoablation or the left atrial maze procedure in association with mitral valve surgery was performed in 80 patients with atrial fibrillation and enlarged left atria (> or =60 mm). Among them, 44 patients had the concomitant volume reduction technique (VR group); continuous horizontal mattress sutures for left atrial plication were placed on the left atrial wall along the pulmonary vein isolation line. Cryoablation was applied to the suture line so that the plicated left atrium is anatomically and electrically isolated. Another 36 patients did not have the volume reduction technique (control group).

RESULTS

The VR group had preoperative left atrial diameters similar to those of the control group (67.1 +/- 7.8 vs 64.5 +/- 6.7 mm) and a longer preoperative duration of atrial fibrillation (14.1 +/- 5.4 vs 9.5 +/- 5.1 years, P < .05) but had smaller postoperative left atrial diameters (47.6 +/- 6.3 vs 62.1 +/- 7.9 mm, P < .01). There were no differences in mean crossclamp/bypass time and chest tube drainage for 12 hours between the groups. Twelve months after surgical intervention, the sinus rhythm recovery rate of the VR group was better than that of the control group (90% vs 69%, P < .05).

CONCLUSIONS

Even in patients with long-standing atrial fibrillation and an enlarged left atrium, maze procedures concomitant with the novel left atrial volume reduction technique improved the sinus rhythm recovery rate without increasing complications. Although further study with a larger number of patients and a longer follow-up period is needed, this safe and thus far potent technique that catheter-based ablation cannot copy might extend indication of the Cox maze procedure for patients with tough atrial fibrillation.

Clinical determinants of sinus conversion by radiofrequency maze procedure for persistent atrial fibrillation in patients undergoing concomitant mitral valvular surgery

The radiofrequency Maze procedure can effectively restore sinus rhythm in most patients with atrial fibrillation (AF) and mitral valve disease. AF after cardiac surgery is associated with increased morbidity and mortality. However, clinical determinants of long-term postoperative AF after the radiofrequency Maze procedure and concomitant mitral valve surgery are poorly defined. This study comprised 99 consecutive patients with persistent AF and mitral valve disease who underwent radiofrequency Maze procedures and concomitant mitral valvular operations. The predictive values of clinical variables for postoperative AF were examined. After a mean follow-up period of 46.1+/-24.6 months, 83 patients (83.8%) had sinus conversion after the Maze procedure, and 16 patients remained in persistent or paroxysmal AF. Multiple logistic regression analysis determined that predictors of sinus conversion were preoperative left atrial diameter (odds ratio [OR] 1.127 per 1-mm increment in left atrial diameter, 95% confidence interval [CI] 1.045 to 1.215, p<0.002) and the duration of AF (OR 1.022 per 1-month increment in duration of AF, 95% CI 1.009 to 1.035, p<0.001). Discriminant analysis showed that the sinus conversion rate was significantly lower in patients with preoperative left atrial diameters>56.8 mm (p<0.001) or AF duration>66 months (p<0.001) than in patients with preoperative left atrial diameters<56.8 mm or AF duration<66 months. In conclusion, the preoperative left atrial size and duration of AF are primary predictors of sinus conversion by the radiofrequency Maze procedure for patients with persistent AF and mitral valve disease.

Surgical Ablation of Atrial Fibrillation

Surgical ablation of atrial fibrillation (AF) is the most effective means of curing this arrhythmia, with the classic Maze procedure eliminating AF in more than 90% of patients. A complex but safe operation, the Maze procedure has been applied by relatively few surgeons. However, recent advances in the understanding of the pathogenesis of AF and development of new ablation technologies enable surgeons to perform pulmonary vein ablation, create linear left atrial lesions, and remove the left atrial appendage rapidly and safely. Lesions are created under direct vision, minimizing the risk of damage to the pulmonary veins and adjacent mediastinal structures. Most surgical ablation procedures have been performed in conjunction with mitral valve surgery, the combination of mitral valve repair and cure of AF enabling patients to avoid lifelong anticoagulation. Recently developed surgical instrumentation now enables thoracoscopic and keyhole approaches, facilitating extension of epicardial AF ablation and excision of the left atrial appendage to patients with isolated AF and no other indication for cardiac surgery.

Atrial Pacemaker Complex Preserved Radiofrequency Maze Procedure Reducing the Incidence of Sick Sinus Syndrome in Patients With Atrial Fibrillation

BACKGROUND

The Cox maze III procedure can effectively restore sinus rhythm in most patients with permanent atrial fibrillation (AF). However, previous studies have shown that the maze procedure results in significant sinus node dysfunction, and, consequently, a considerable number of patients required postoperative pacemaker implantation.

HYPOTHESIS

This study investigates the hypothesis that the modification of the Cox III maze procedure, to avoid injuring the sinus node and the atrial physiologic pacemaker complex, will reduce the incidence of sick sinus syndrome following surgery.

METHODS AND RESULTS

This study investigated 71 patients with permanent AF and mitral valve disease who were undergoing concomitant open-heart surgery. Most atrial incisions in the Cox maze III procedure were replaced with radiofrequency ablation, and the intercaval counterablation was moved posterolaterally to avoid injury to the sinus node and atrial pacemaker complex. At a mean (+/- SD) follow-up time of 46.5 +/- 24 months, 59 patients (83.1%) regained sinus rhythm without receiving antiarrhythmic drug therapy or undergoing electrical cardioversion. The transmitral atrial wave was observed in 44 patients (62%), and the transtricuspid atrial wave was also observed in 53 patients (74.6%). Late sinus node dysfunction developed in only two patients (2.8%), who received permanent pacemaker implantation.

CONCLUSION

This modified radiofrequency maze procedure produces few patients with sick sinus syndrome and effectively restores sinus rhythm and atrial transport function in most patients with permanent AF undergoing concomitant open-heart surgery.

Monopolar and Bipolar Radiofrequency Ablation Surgery: 3-Year Experience in 90 Patients with Permanent Atrial Fibrillation

OBJECTIVE

In our population, permanent atrial fibrillation (pAF) is a serious concomitant problem in patients scheduled for open heart surgery. The high incidence necessitates reliable methods of treating pAF efficiently. We report our 3-year experience with a safe concept of using monopolar and bipolar radiofrequency (RF) ablation procedures.

METHODS

Ninety patients (mitral, n = 56; aortic, n = 22; aortic and mitral, n = 1; coronary artery bypass grafting, n = 11) underwent either monopolar (n = 77) or, recently, bipolar (n = 13) RF ablation procedures that produced encircling isolation lesions around the left and the right pulmonary veins (PVs) and a connection line between the two. Amiodarone was given for 3 months after surgery.

RESULTS

Hospital mortality was 2.2%. At follow-up, 75% of the patients were in stable sinus rhythm (SR). Preoperative pAF duration, etiology of heart disease, and type of RF energy application were not predictive of the risk of persisting pAF after surgery. Whereas patients (50 of 90) with small preoperative left atrial (LA) diameters (<56 mm) had SR in almost 90% of cases, large preoperative LA diameters (>or=56 mm; 40 of 90 patients) were associated with a significant risk of persisting pAF (P < .05).

CONCLUSION

Particularly in cases of small preoperative LA diameters, isolation of the PVs using either monopolar or bipolar RF ablation procedures in combination with amiodarone therapy represents a safe and efficient option for curing pAF in patients undergoing open heart surgery.

Preoperative Atrial Size Predicts the Success of Radiofrequency Maze Procedure for Permanent Atrial Fibrillation in Patients Undergoing Concomitant Valvular Surgery

BACKGROUND

The radiofrequency (RF) maze procedure can effectively restore sinus rhythm and atrial transport function in the majority of patients with permanent atrial fibrillation (AF) and mitral valve disease. No previous study has described a cutoff value of preoperative atrial size determined by the discriminant analysis in predicting the success of sinus conversion by the RF maze procedure for permanent AF in patients with mitral valve disease.

METHODS AND RESULTS

This study included 81 patients with permanent AF and mitral valve disease who underwent the RF maze IV procedure while undergoing concomitant valvular operations. There was one surgical death (1.2%). Another patient died of acute necrotizing pancreatitis 13 months later. Two patients (2.5%) developed sick sinus syndrome and received transvenous permanent pacemaker implantation. In the remaining 77 patients, there were 38 men and 39 women, with a mean (+/- SD) age of 51 +/- 11 years. At a mean follow-up time of 38 months, 65 patients (84.4%) had persistent sinus conversion that had been accomplished by the RF maze procedure (group 1), and 12 patients (15.6%) did not regain sinus rhythm (group 2). We evaluated the preoperative variables between the two groups. Univariate analysis demonstrated that the preoperative left atrial area and the left atrial diameter of group 1 patients were significantly smaller than those of group 2 patients. Group 1 had significantly fewer patients associated with tricuspid valve disease than did group 2. By multiple stepwise logistic regression analysis, only the preoperative left atrial area was an independent determinant of sinus conversion by the RF maze procedure (odds ratio, 0.961; 95% confidence interval, 0.935 to 0.988; p < 0.005). Linear discriminant analysis demonstrated that the sensitivity and specificity of the cutoff value of 56.25 cm(2) of the preoperative left atrial area in predicting the sinus conversion by the RF maze procedure were 50.0% and 86.2%, respectively, and the positive and negative predictive values were 40.0% and 90.3%, respectively.

CONCLUSION

The preoperative left atrial area is an independent determinant of sinus conversion by the RF maze procedure for patients with permanent AF and mitral valve disease.

Advances in the surgical treatment of atrial fibrillation

There has been a resurgence in the surgical treatment of AF. Although the Maze procedure is extremely effective at curing AF, new surgical approaches are far simpler and include pulmonary vein isolation, left atrial lesions, and excision of the left atrial appendage. Currently applied as an adjunct to other cardiac operations, these new approaches are being modified for thoracoscopic, minimally invasive, epicardial AF ablation. This minimally invasive procedure will enable rapid and effective cure of AF in large numbers of patients.

Predictors of Failure to Cure Atrial Fibrillation with the Mini-Maze Operation

BACKGROUND

Maze-III is a complex surgical procedure designed to treat chronic atrial fibrillation. A reduction in the number of right and left atrial incisions could decrease the operative time. The aim of this study was to assess the results of a mini-maze operation and to define predictors of its failure.

METHODS

Between 1995 and 2000, 72 patients (mean age 64 +/- 9 years) undergoing cardiac surgery had a concomitant mini-maze operation for symptomatic chronic atrial fibrillation. Three and 12 months post-operatively, heart rhythm and left atrial transport functions were assessed by electrophysiology, echocardiography, and magnetic resonance imaging. Multivariate analysis was performed to identify predictors of failure of the mini-maze operation.

RESULTS

Operative mortality was 1.4% (1/72). Death during follow-up occurred in 5.6% of patients (4/71), in one due to chronic heart failure. After 1 year, 80% of patients (48/60) were either in sinus rhythm (n = 43; 72%) or had a pacemaker (n = 5; 8%) implanted due to sick sinus syndrome. Intermittent and chronic atrial fibrillation was found in 20% of patients (12/60). Preoperative duration of atrial fibrillation (p = 0.05), preoperative left atrial diameter (p = 0.001), preoperative right atrial diameter (p = 0.02), a reduced left ventricular ejection fraction (p = 0.03), an increased left ventricular end-diastolic diameter (p = 0.04), and the presence of mitral valve stenosis (p = 0.001) were found to be univariate predictors of failure of the mini-maze operation 1 year postoperatively. Multivariate analysis defined preoperative diagnosis of mitral valve stenosis (p = 0.005; OR 117.5), longer duration of preoperative atrial fibrillation (p = 0.01; OR 1.33), and increased preoperative left ventricular end-systolic diameter (p = 0.02; OR 1.2) as incremental independent risk factors for failure of the mini-maze operation to cure chronic atrial fibrillation.

CONCLUSION

The mini-maze operation is a safe procedure with similar results to that of Cox's Maze-III operation. The less-invasive mini-maze operation could be applicable even to patients with severely reduced left ventricular function, in whom complex cardiac surgery has to be performed concomitantly as well as in those presenting severe comorbidities.

Surgical treatment of arrhythmias related to congenital heart diseases

BACKGROUND

Supraventricular arrhythmias complicate operated and unoperated congenital heart disease, especially when atrial dilatation coexists.

METHODS

We evaluated the results of intraoperative ablation in a group of 23 patients with chronic supraventricular tachyarrhythmias (mostly intraatrial reentry) that were unresponsive to conventional medical therapy. All procedures were performed consecutively between September 1999 and November 2001. Ablation was done during redo operations (Fontan conversion to total cavopulmonary connection in 16 patients) in 18 patients and during primary surgical correction in 5 patients. The mean age at operation was 25 +/- 12 years (2 to 50 years). Cryoablation was done in 10 patients and radiofrequency ablation in 13 patients. Nineteen patients had ablation in one atrium and 4 had ablation in both atria. A generous atrial reduction was always performed at the end of the operation.

RESULTS

The operative mortality rate was 13% (3 patients) from causes unrelated to ablation. In 20 survivors, the ablation was effective immediately. Eight patients required a permanent pacemaker. During a mean follow-up of 22 +/- 4 months, atrial arrhythmias recurred in 25% (5 patients) and were controlled with medical therapy, whereas 1 patient required pacemaker implantation.

CONCLUSIONS

Intraoperative treatment of unresponsive atrial tachyarrhythmias associated with operated or unoperated congenital heart disease is feasible and the midterm results are encouraging.

Atrial fibrillation: current surgical options and their assessment

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with morbidity and mortality. Traditional surgical treatment of AF is the Cox-Maze III procedure, a complicated operation. New surgical approaches include alternate energy sources (radiofrequency, microwave, cryothermy) and simplified left atrial lesion sets. These operations cure AF in 70% to 80% of patients. This review describes contemporary and emerging surgical approaches to AF, synthesizes results of these operations, and proposes new standards for reporting results of AF treatment.

Application of microwave energy in cardiac tissue ablation: from in vitro analyses to clinical use

BACKGROUND

Recently, there has been renewed interest in simplifying a surgical cure for atrial fibrillation. Microwave energy ablation provides an easier and faster surgical technique, in lieu of traditional "cut and sew," which can also be applied on the beating heart.

METHODS

Specific absorption rate (SAR) and thermal profiles were determined after microwave energy ablation intended for clinical application. Lesion geometry measures obtained in vitro with tissue equivalent media were compared with values collected from animal myocardium.

RESULTS

Thermal profile analysis demonstrated lesion penetration depths of 2.5, 3, and 5 mm after 8, 16, and 24 seconds, respectively, with microwave power application of 40 W. Dosimetric studies performed using animal myocardium corresponded to the thermal profile analysis and showed that lesion depth was controlled by the output power and the ablation time.

CONCLUSIONS

Lesion geometry in tissue using microwave energy is similar to that predicted from in vitro analysis. The ablation depths and thermal profile of microwave ablation is favorable for performing atrial ablation, and this is corroborated by favorable early clinical results.

Radiofrequency ablation of atrial fibrillation during mitral valve surgery

Twenty-three patients underwent endocardial radiofrequency ablation of atrial fibrillation (AF) during mitral valve procedures with a previously described left atrial lesion pattern. A temperature-controlled 7-coil surgical probe delivered 60-second lesions at 80 degrees C. The left atrial appendage was oversewn after ablation. Ages ranged from 28 to 88 years. Nineteen patients had chronic AF that was present for over 1 year in 74%; 12 patients had rheumatic mitral stenosis. Mean left atrial diameter was 5.4 +/- 0.7 cm. There was 1 operative death unrelated to the ablation, and no strokes or ablation-related complications were observed. At mean follow-up of 32.5 weeks, 86% of the 22 survivors were in sinus rhythm. All 18 patients with left atrial diameter <6 cm are in sinus rhythm. All postoperative atrial flutter was transient, and no patients required subsequent transcatheter ablation. This lesion pattern is safe and effective when applied in the method described here. It appears to be a reasonable alternative to the complete Maze 3 lesion pattern in patients with mitral valve disease.

Validation of a left atrial lesion pattern for intraoperative ablation of atrial fibrillation

BACKGROUND

Evidence that atrial fibrillation may begin in early stages from triggers or reentry circuits primarily in the left atrium suggests that the entire Maze 3 lesion pattern may be unnecessary. In the present study we describe a new left atrial lesion pattern for intraoperative linear ablation of chronic atrial fibrillation.

METHODS

Endocardial radiofrequency ablation was performed on 12 dogs with chronic atrial fibrillation. Lesions to isolate pulmonary veins in pairs, the left atrial appendage, and connecting lesions between these structures were administered in a randomized approach.

RESULTS

Twelve dogs were in chronic atrial fibrillation for 31 +/- 21 days before ablation. Atrial fibrillation was successfully ablated and rendered noninducible in all 12 dogs. All treatment failures observed with less than the full lesion pattern became a success when the remaining lesions were given.

CONCLUSIONS

Atrial fibrillation ablation using this left atrial lesion pattern is highly successful in this model. This approach may have significant utility as a concomitant procedure for patients with atrial fibrillation undergoing mitral valve procedures.

Radiofrequency lesions produced by handheld temperature controlled probes for use in atrial fibrillation surgery

OBJECTIVES

Detailed analysis of the size and shape of lesions produced by handheld radiofrequency ablation devices at open heart surgery has not been reported previously.

METHODS

Radiofrequency lesions were made from the epicardial surface of the cardiac ventricles in open-chested dogs. The effects of electrode size, electrode temperature and duration of ablation were studied. In a second group of experiments simultaneous multielectrode ablation was performed on the ventricular epicardium after cold cardioplegia.

RESULTS

Using a single 12 x 2.5 mm electrode and a target temperature of 80 degrees C the lesion depth increased from 3.8+/-0.9 mm at 15 s, to 6.1+/-0.9 mm at 120 s (P=0.01). Increasing the target temperature from 70 to 90 degrees C (for 60 s) increased lesion depth from 5.0+/-1.2 to 5.6+/-1.7 mm (P=0.2). There was no difference in depth of lesions with the two electrode widths (4.0+/-0.5 mm (large) vs. 3.9+/-1.0 mm (small)). Lesions produced using the multielectrode probe (80 degrees C, 60 s) were 30-35 mm long with even penetration into the tissue. The mean depth of these lesions on microscopic sections was 3.9 mm. The mean width was 7.1 mm.

CONCLUSIONS

Handheld probes can be used to make deep linear lesions in the myocardium. Lesions expand rapidly and are wider than they are deep. A multielectrode ablation device allows rapid formation of linear lesions.

Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin modification

BACKGROUND

The Cox-maze procedure combined with an operation for organic heart disease is highly successful in the elimination of chronic atrial fibrillation. However, it prolongs significantly the aortic cross-clamp and operating time. In this study, a simplified left atrial maze procedure, which is a short procedure performed using a surgical radiofrequency ablation probe, is added to elective open heart procedures in patients with atrial fibrillation.

METHODS

Forty-eight adults with atrial fibrillation (duration, 6 months to 36 years) underwent elective open heart operations (isolated valve procedures or coronary artery bypass grafting, n = 27 patients; combined procedures, n = 21 patients) combined with intraoperative radiofrequency ablation of the left atrium. The postoperative follow-up period ranged from 1 to 11 months (mean, 4 months). Possible predictors for persistent postoperative atrial fibrillation were determined among 40 variables by univariate and multivariate analyses.

RESULTS

Intraoperative radiofrequency ablation prolonged the aortic cross-clamp time for 6 to 14 minutes (mean, 11 minutes). Freedom from atrial fibrillation was 100% intraoperatively, 25% at 1 week after operation (12 of 48 patients), 59% at 1 month postoperatively (16 of 27 patients), 64% at 3 months postoperatively (16 of 25 patients), and 92% at 6 months postoperatively (12 of 13 patients). The only predictor of postoperative atrial fibrillation was the presence of coronary artery disease (odds ratio, 7.5; 80% confidence interval, 2.24-25.13).

CONCLUSIONS

Intraoperative radiofrequency ablation of the left atrium combined with an operation for organic heart disease effectively eliminates atrial fibrillation without significant prolongation of the aortic cross-clamp and operative time. The presence of coronary artery disease decreases the success rate during the first 6 postoperative months.

[Surgical treatment of atrial fibrillation and coronary artery bypass without the use of extracorporeal circulation: case report]

A 71-year-old man presented stable angina due to severe coronariophaty and chronic atrial fibrillation. A radial approach for atrial fibrillation and three coronary artery bypass grafts were performed without cardiopulmonary bypass. The procedure for the arrhythmia ablation was done epicardially with a multipolar radiofrequency catheter. Intraoperatively, the patient regained normal sinus rhythm, with an uneventful postoperative course. Postoperative echocardiography demonstrated the presence of an atrial A wave.

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.

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.

In vivo and in vitro study of radio-frequency application with a new long linear probe: implication for the maze operation

BACKGROUND

The maze operation for atrial fibrillation is effective but highly invasive. We tested, both in vitro and in vivo, a new technique for creating long linear atrial lesions with a custom-made, 25-mm long, stainless-steel, linear probe and a corresponding 500-kHz generator for assistance in the maze operation.

METHODS

In the in vitro study with the isolated canine atria, the power of the delivered radio-frequency energy and the saline irrigating flow rate were changed independently, and the sizes of the lesions were measured. In the in vivo study radio-frequency energy was delivered to 4 portions (ie, the smooth and trabeculated portions of the right and left atria). The sizes of the lesions were measured, and the histologic features of the lesions were examined. Electrical isolation of the right atrial appendage from the remaining right atrium was attempted by using this linear probe.

RESULTS

In the in vitro study the size of the lesion became larger as the delivered power was increased, although the lesion was limited when the flow rate was high. In the in vivo study the size of the lesion was equal at the 4 different sites. Histologic examinations demonstrated linear and transmural lesions, and electrophysiologic examinations revealed conduction block between the right atrial appendage and the remaining right atrium.

CONCLUSIONS

The new original long linear probe was effective for creating transmural linear atrial lesions with the irrigation method, presenting the possibility of an intraoperative technique that mimics the maze procedure.

Limited posterior left atrial cryoablation in patients with chronic atrial fibrillation undergoing valvular heart sugery

OBJECTIVES

We sought to evaluate whether a limited surgical cryoablation of the posterior region of the left atrium was safe and effective in the cure of atrial fibrillation (AF) in patients with associated valvular heart disease.

BACKGROUND

Extensive surgical ablation of AF is a complex and risky procedure. The posterior region of the left atrium seems to be important in the initiation and maintenance of AF.

METHODS

In 32 patients with chronic AF who underwent heart valve surgery, linear cryolesions connecting the four pulmonary veins and the posterior mitral annulus were performed. Eighteen patients with AF who underwent valvular surgery but refused cryoablation were considered as the control group.

RESULTS

Sinus rhythm (SR) was restored in 25 (78%) of 32 patients immediately after the operation. The cryoablation procedure required 20 +/- 4 min. There were no intraoperative and perioperative complications. During the hospital period, one patient died of septicemia. Thirty-one patients reached a minimum of nine months of follow-up. Two deaths occurred but were unrelated to the procedure. Twenty (69%) of 29 patients remained in SR with cryoablation alone, and 26 (90%) of 29 patients with cryoablation, drugs and radiofrequency ablation. Three (10%) of 29 patients remained in chronic AF. Right and left atrial contractility was evident in 24 (92%) of 26 patients in SR. In control group, two deaths occurred, and SR was present in only four (25%) of 16 patients.

CONCLUSIONS

Linear cryoablation with lesions connecting the four pulmonary veins and the mitral annulus is effective in restoration and maintenance of SR in patients with heart valve disease and chronic AF. Limited left atrial cryoablation may represent a valid alternative to the maze procedure, reducing myocardial ischemic time and risk of bleeding.

Cox-Maze procedure for atrial fibrillation: Mayo Clinic experience

The Cox-Maze procedure corrects atrial fibrillation in 90% of patients, and successful operation restores sinus rhythm, thereby reducing risks of thromboembolism and anticoagulant-associated hemorrhage. Symptoms such as palpitation and fatigability also improve with restoration of atrioventricular synchrony. At the Mayo Clinic, 221 Cox-Maze procedures were performed from March 1993 through March 1999. Over 75% of patients had associated cardiac disease and concomitant operations. Overall, early mortality was 1.4%, and the incidence of postoperative pacemaker implantation was 3.2%. Limiting incisions to the right atrium simplifies the operation for patients who primarily have tricuspid valve disease, and in early follow-up, outcome appeared to be as good as that achieved with biatrial incisions. The Cox-Maze procedure has proved particularly useful for patients with preoperative atrial fibrillation who require valvuloplasty for acquired mitral valve regurgitation; 87 patients have had this combined procedure, and there have been no early deaths. Further, our experience indicates that ventricular dysfunction is not a contraindication for operation and that restoration of sinus rhythm after the Cox-Maze procedure improves left ventricular ejection fraction in most patients.

The closed heart MAZE: a nonbypass surgical technique

BACKGROUND

The MAZE-III is the surgical treatment of choice for medically refractory atrial fibrillation. Although a number of nonsurgical techniques are evolving to duplicate the transmural atrial lesions of the MAZE-III, the surgical atriotomy remains the gold standard for conduction block. It was the objective of this study to surgically create the atrial incisions of the MAZE-III without the use of cardiopulmonary bypass.

METHODS

A technique was developed to create and intersect the linear incisions of the MAZE-III on 10 beating canine hearts without the use of cardiopulmonary bypass using a "tunnel" of atrial tissue. The effectiveness of the procedure was tested by atrial burst pacing.

RESULTS

This technique was successfully performed on 10 mongrel dogs without operative mortality. Preoperatively, sustained atrial fibrillation (>30 seconds) was induced in all animals. Postoperatively, all the animals remained in sinus rhythm even after burst pacing.

CONCLUSIONS

In an experimental canine model, the MAZE-III can be performed on beating hearts without the assistance of cardiopulmonary bypass using a "tunnel" technique. This technique allows for the immediate assessment of electrophysiologic and mechanical function after the MAZE-III, or any other type of procedure using the "maze principle" and may find future application in the clinical arena.

Experimental ablation study using a new long linear probe in isolated porcine hearts

We studied a new technique for creating long linear lesions in hearts using a custom-made linear probe. Radiofrequency (RF) energy applications using a 25-mm long stainless steel linear probe and a corresponding 500-kHz energy generator were tested, creating 90 lesions in isolated porcine hearts. The RF current was applied between the linear probe and a large patch electrode attached to the back of the specimen. Three parameters, comprising the power of the delivered energy, the pressure of contact between the probe and the specimen, and the duration of energy delivery were changed independently and the size of the resulting lesions was measured. All 90 lesions were transmural, well demarcated and created by a single stationary RF application. Lesion length and width increased with: 1) increasing power, when the other two parameters were maintained at constant levels, 2) increasing contact pressure, when the other two parameters were maintained at constant levels, and 3) increasing duration of energy delivery when the other two parameters were maintained at constant levels. The maximum width of the lesions was 3.7 mm. No overheating of any of the specimens was observed. In conclusion, the new original long linear probe used in this study was effective for creating transmural linear lesions, presenting the possibility of a worthwhile contribution to the maze surgical procedure applied to atrial fibrillation.

Partial maze procedure is effective treatment for chronic atrial fibrillation associated with valve disease

The maze procedure may be performed in combination with valve operations to treat chronic atrial fibrillation associated with valve dysfunction. Although we initially used the modified Cox maze III procedure, a more limited partial maze procedure is now preferred because the left atrium might be considered as the electrical impetues for atrial fibrillation. In this study we compared the results of 30 patients (group I) who underwent the full biatrial modified Cox maze III and 20 (group II) patients the partial maze procedure. While the rates of restored sinus rhythm were the same in both groups at 6-month follow-up (I: 83.3%, vs II: 80%), the following advantages were noted in the patients undergoing the partial maze procedure: shorter operative times, lesser elevations of creatine phosphokinase, lower rate of blood transfusion, lower rate of junctional rhythm soon after the operation, and a higher P wave in those patients with restored sinus rhythm. The effectiveness of the partial maze procedure seems equal to that of the biatrial modified Cox maze III procedure for atrial fibrillation associated with valve disease. The partial maze procedure is simple and less invasive, and thus might be applied more frequently as an additional procedure to valve operations without additional risk.