Surgical treatment of atrial fibrillation using radiofrequency energy

Effects of Atrial Fibrillation Radiofrequency Ablation in Patients Aged > 75 Years Undergoing Mitral Valve Surgery

BACKGROUND

Few data exist about the efficacy of radiofrequency (RF) maze procedures in elderly patients with atrial fibrillation (AF) undergoing surgery for mitral valve disease. The aim of the present investigation was to evaluate the effects of AF ablation associated with mitral valve surgery on the recovery and long-term maintenance of sinus rhythm in elderly patients aged > 75 years. Moreover, we evaluated the effects on survival.

METHODS AND RESULTS

This study included 96 consecutive patients with AF (42 men and 56 women) aged > 75 years (mean age 78 ± 3) who underwent RF ablation associated with mitral valve surgery (group I). This group was compared to 209 younger patients (mean age 65 ± 8 years) treated in the same period (group II). Baseline clinical and echocardiographic characteristics were similar in the two groups. Four patients died during hospitalization, one aged > 75 years. In surviving patients at the end of the follow-up period, sinus rhythm was present respectively in 64% of the elderly and 74% of younger patients (p = 0.778). The rate of persistence of sinus rhythm without AF recurrences (38% vs. 41%, p = 0.705) was similar in the two groups. After surgery, sinus rhythm was frequently never regained in aged patients (27% vs. 20%, p = 0.231). Elderly patients more frequently needed permanent pacing and had more hospitalizations and a higher number of non-AF atrial tachyarrhythmias. At eight-year follow-up, survival was lower in older patients (48% aged > 75 vs. 79% aged < 75 years).

CONCLUSION

Elderly patients had a similar long-term rate of stable sinus rhythm maintenance in comparison to younger patients after AF radiofrequency ablation associated with mitral valve surgery. However, they needed more frequent permanent pacing and had higher rates of hospitalizations and post-procedural atrial tachyarrhythmias. The effects of survival are difficult to evaluate due to the different life expectancies of the two groups.

Advances in Atrial Fibrillation Ablation: Energy Sources Here to Stay

Energy sources used for catheter ablation of atrial fibrillation (AF) ablation have undergone an exceptional journey over the past 50 years. Traditional energy sources, such as radiofrequency and cryoablation, have been the mainstay of AF ablation. Novel investigations have led to inclusion of other techniques, such as laser, high-frequency ultrasound, and microwave energy, in the armamentarium of electrophysiologists. Despite these modalities, AF has remained one of the most challenging arrhythmias. Advances in the understanding of electroporation promise to overcome the shortcomings of conventional energy sources. A thorough understanding of the biophysics and practical implications of the existing energy sources is paramount.

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.

Mid-Term Results of Surgical Treatment of Atrial Fibrillation in Valvular Heart Disease Assesed by Speckle Tracking Echocardiography

Background

Atrial fibrillation frequently affects patients with valvular heart disease. Ablation of atrial fibrillation during valvular surgery is an alternative for restoring sinus rhythm.

Objectives

This study aimed to evaluate mid-term results of successful atrial fibrillation surgical ablation during valvular heart disease surgery, to explore left atrium post-ablation mechanics and to identify predictors of recurrence.

Methods

Fifty-three consecutive candidates were included. Eligibility criteria for ablation included persistent atrial fibrillation <10 years and left atrium diameter < 6.0 cm. Three months after surgery, echocardiogram, 24-hour Holter monitoring and electrocardiograms were performed in all candidates who maintained sinus rhythm (44 patients). Echo-study included left atrial deformation parameters (strain and strain rate), using 2-dimensional speckle-tracking echocardiography. Simultaneously, 30 healthy individuals (controls) were analyzed with the same protocol for left atrial performance. Significance was considered with a P value of < 0.05.

Results

After a mean follow up of 17 ± 2 months, 13 new post-operative cases of recurrent atrial fibrillation were identified. A total of 1,245 left atrial segments were analysed. Left atrium was severely dilated in the post-surgery group and, mechanical properties of left atrium did not recover after surgery when compared with normal values. Left atrial volume (≥ 64 mL/m²) was the only independent predictor of atrial fibrillation recurrence (p = 0.03).

Conclusions

Left atrial volume was larger in patients with atrial fibrillation recurrence and emerges as the main predictor of recurrences, thereby improving the selection of candidates for this therapy; however, no differences were found regarding myocardial deformation parameters. Despite electrical maintenance of sinus rhythm, left atrium mechanics did not recover after atrial fibrillation ablation performed during valvular heart disease surgery.

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.

[The results of pulmonary veins isolation to prevent postoperative atrial fibrillation]

AIM

To compare an efficacy of primary surgical (epicardial bipolar pulmonary veins isolation) and pharmacological (amiodarone) prevention of postoperative atrial fibrillation.

MATERIAL AND METHODS

The study included 117 patients with coronary artery disease without previous paroxysms of atrial fibrillation who were randomized into 3 groups. The first (I) group (n=39) included patients who underwent coronary artery bypass grafting without radiofrequency ablation of pulmonary veins and prophylactic amiodarone administration. The second (II) group (n=38) consisted of patients who received amiodarone as a prevention of postoperative atrial fibrillation. In the third (III) group (n=40) simultaneous CABG and pulmonary veins isolation were made.

RESULTS

The incidence of atrial fibrillation in early postoperative period was significantly lower in the 3rd group compared with control group (90% vs 69.2%, p=0.021). 1-year freedom from atrial fibrillation was 97.5% in group III vs. 84.2% in group II (p=0.004). In group I the incidence of early postoperative atrial fibrillation was 30.8% with following decrease to 17.9% in 12 months.

CONCLUSION

Simultaneous preventive pulmonary veins isolation during CABG is safe and effective, significantly reduces duration of hospital-stay and incidence of postoperative atrial fibrillation.

History of Cardiothoracic Surgery at Columbia University: A Century at the Vanguard of Clinical Care, Education, and Innovation

The Columbia University Cardiothoracic Surgery Program dates back to the earliest days of the specialty itself, when the first pioneers ventured into the chest, and eventually the heart, to treat diseases previously believed to be beyond the reach of medicine. This spirit of innovation, creativity, and vision has grown over the ensuing century and has driven the development of advances that have defined the specialty and saved countless lives. From novel techniques for the repair of complex congenital cardiac defects and acquired cardiovascular diseases, to comprehensive management of lung and esophageal maladies, and to the marvel of minimally invasive and percutaneous interventions, the march of progress has never been stronger, more dramatic, or more consequential that it is at Columbia today. Fueled by people who -- as descendants of those early pioneers -- have been raised in the "Columbia culture," the commitment to innovation and education has never been greater.

Surgical Ablation of Atrial Fibrillation Using Energy Sources

Surgical ablation, concomitant with other operations, is an option for treatment in patients with chronic atrial fibrillation. The aim of this study is to present a literature review on surgical ablation of atrial fibrillation in patients undergoing cardiac surgery, considering energy sources and return to sinus rhythm. A comprehensive survey was performed in the literature on surgical ablation of atrial fibrillation considering energy sources, sample size, study type, outcome (early and late), and return to sinus rhythm. Analyzing studies with immediate results (n=5), the percentage of return to sinus rhythm ranged from 73% to 96%, while those with long-term results (n=20) (from 12 months on) ranged from 62% to 97.7%. In both of them, there was subsequent clinical improvement of patients who underwent ablation, regardless of the energy source used. Surgical ablation of atrial fibrillation is essential for the treatment of this arrhythmia. With current technology, it may be minimally invasive, making it mandatory to perform a procedure in an attempt to revert to sinus rhythm in patients requiring heart surgery.

Performance of a novel bipolar/monopolar radiofrequency ablation device on the beating heart in an acute porcine model

OBJECTIVE

Although the advent of ablation technology has simplified and shortened surgery for atrial fibrillation, only bipolar clamps have reliably been able to create transmural lesions on the beating heart. Currently, there are no devices capable of reproducibly creating the long linear lesions in the right and left atria needed to perform a Cox-Maze procedure. This study evaluated the performance of a novel suction-assisted radiofrequency device that uses both bipolar and monopolar energy to create lesions from an epicardial approach on the beating heart.

METHODS

Six domestic pigs underwent median sternotomy. A dual bipolar/monopolar radiofrequency ablation device was used to create epicardial linear lesions on the superior and inferior vena cavae, the right and left atrial free walls, and the right and left atrial appendages. The heart was stained with 2,3,5-triphenyl-tetrazolium chloride, and each lesion was cross-sectioned at 5-mm intervals. Lesion depth and transmurality were determined.

RESULTS

Transmurality was documented in 94% of all cross sections, and 68% of all ablation lines were transmural along their entire length. Tissue thickness was not different between the transmural and nontransmural cross sections (3.1 ± 1.3 and 3.4 ± 2.1, P = 0.57, respectively), nor was the anatomic location on the heart (P = 0.45 for the distribution). Of the cross sections located at the end of the ablation line, 11% (8/75) were found to be nontransmural, whereas only 4% (8/195) of the cross sections located within the line of ablation were found to be nontransmural (P = 0.04). Logistic regression analysis demonstrated that failure of the device to create transmural lesions was associated with low body temperature (P = 0.006) but not with cardiac output (P = 0.54).

CONCLUSIONS

This novel device was able to consistently create transmural epicardial lesions on the beating heart, regardless of anatomic location, cardiac output, or tissue thickness. The performance of this device was improved over most devices previously tested but still falls short of ideal clinical performance. Transmurality was lower at the end of the lesions, highlighting the importance of overlapping lines of ablation in the clinical setting.

A modified cryo-maze procedure via the superior transseptal approach

The superior transseptal approach provides excellent exposure for mitral valve reconstruction. For atrial fibrillation, cryoablation is less invasive, simpler, and safer than the Cox maze operation. Combining the superior transseptal approach and cryoablation for mitral valve procedures yields a high recovery rate from atrial fibrillation, similar to that of radiofrequency ablation. Cryoablation-related complications such as thromboembolic events or requirement for a permanent pacemaker were not observed in our consecutive series. Cryoablation is also cost-effective.

Curative surgery for atrial fibrillation: current status and minimally invasive approaches

Atrial fibrillation (AF) is the most common disorder of heart rhythm. Affecting 2.2 million Americans and millions more worldwide, AF is a dangerous and costly epidemic. AF is associated with an increased risk of stroke, premature death and billions of dollars in healthcare expenditures. Traditional treatments of AF, which include medications aimed at rate or rhythm control have been disappointing, leaving most patients in AF and failing to eliminate the risk of stroke. In contrast, advances in surgical and catheter-based therapies offer the chance to cure AF. With more than a decade of experience, surgical treatment of AF is the most effective means of curing this arrhythmia. The classic Maze procedure eliminates AF in more than 90% of patients. A complex but safe operation, the Maze procedure is applied by relatively few surgeons. Recently, however, there has been a resurgence of interest in surgical treatment of AF. Advances in the understanding of the pathogenesis of AF and development of new ablation technologies enable surgeons to perform pulmonary vein ablation and create linear left atrial lesions rapidly and safely. Such procedures, which are generally applied to patients with AF and valvular heart disease, add 15 minutes to operative time and cure AF in approximately 80% of patients. New ablation technologies have been adapted to enable thoracoscopic and minimally invasive surgical AF ablation in patients with isolated AF, extending the possibility of cure to large numbers of patients.

Radiofrequency ablation of atrial fibrillation in patients with mechanical mitral valve prostheses safety, feasibility, electrophysiologic findings, and outcomes

OBJECTIVES

The purpose of this study was to evaluate the feasibility, safety, and outcomes of radiofrequency ablation of atrial fibrillation (AF) in patients with mechanical mitral valve replacement (MVR).

BACKGROUND

The role of ablative therapy in patients with MVR is not yet established, with safety concerns and very few outcome data.

METHODS

Between January 2003 and December 2008, we followed up 81 patients with MVR undergoing first-time AF ablation (compared with 162 age- and sex-matched controls). Arrhythmia recurrences were identified by symptoms with documentation, event monitoring, Holter monitoring, and electrocardiograms.

RESULTS

All MVR and control patients underwent ablation under therapeutic international normalized ratio. No entrapment of catheters or stroke occurred. There were no differences in terms of procedure-related complications between the groups (p = NS). Patients with MVR had larger atria (p < 0.0001), lower left ventricular ejection fractions (p = 0.0001), and more concomitant atrial flutter at baseline (p < 0.0001). Over a 24-month follow-up, they had higher recurrence rates compared with controls (49.4% vs. 27.7% after a single ablation, p = 0.0006). The creation of flutter lines significantly reduced recurrences in patients with any history of atrial flutter (16.7% vs. 60.9%, p = 0.009). At last follow-up, 82.7% of MVR patients had their arrhythmia controlled (69.1% not receiving antiarrhythmic drugs).

CONCLUSIONS

Radiofrequency ablation is feasible and safe for patients with MVR. It allowed restoration of sinus rhythm in a substantial proportion of patients undergoing ablation. An abnormal atrial substrate underlies recurrences in these patients. The ablation procedure needs to be further refined with a focus on extra pulmonary vein triggers and concomitant flutters to improve outcomes.

Mid-term results for the Maze procedure in patients with non-mitral valvular atrial fibrillation

BACKGROUND

The Maze procedure in patients without mitral valve disease remains controversial, because of the increased invasiveness and operation time required to create additional incisions in the atria. The aim of this study was to assess prognosis following the Maze procedure in patients without mitral valve disease.

METHODS AND RESULTS

One hundred and seven consecutive patients who underwent the Maze procedure between 2002 and 2008 was enrolled in this study. Patients were divided into two groups based on the presence or absence of mitral valve disease. Freedom from atrial fibrillation was compared by multivariate logistic regression analysis at discharge. The Kaplan-Meier method and Cox-proportional hazard analysis adjusted for other predictors were estimated to compare freedom from atrial fibrillation at follow-up. Follow-up was 98% complete and mean duration of follow-up was 457 days. Operation and aorta cross-clamp times were similar between groups. No differences were identified in freedom from atrial fibrillation at discharge (non-mitral valve surgery, 55% vs. mitral valve surgery, 66%) or follow-up (57% vs. 61%, respectively). In multivariate Cox proportional hazard modelling, the presence of mitral valve disease was not associated with a poor success rate of conversion.

CONCLUSIONS

Results of the Maze procedure for atrial fibrillation without mitral valve disease were acceptable. The Maze procedure could be a beneficial option for these patients to avoid adverse events of atrial fibrillation.

Mid-term results of endoscopic mitral valve repair in combination with endocardial or epicardial ablation

OBJECTIVE

Concomitant ablative therapy for atrial fibrillation can be effective at converting patients to normal sinus rhythm and at maintaining a regular rhythm for at least 5 years. We provide herein a comparison of an endocardial approach using Cryoablation with an epicardial approach using a suction-based RF ablation technology.

METHODS

Between February 2004 and January 2009, 325 patients underwent an endoscopic mitral valve repair. Of those patients, 112 (35%) had a history of atrial fibrillation prior to the procedure, all of whom underwent a concomitant ablation procedure. The first group of 78 concomitant ablation patients underwent a left-sided endocardial ablation procedure using a Cryoablation device. The second group of 34 ablation patients underwent a left-sided epicardial ablation procedure using an internally cooled monopolar RF device. No significant differences existed between groups in the preoperative data. All ablated patients were treated by the same Amiodarone protocol. Patients were followed for a minimum of 6 months for determining each ablated patient's rhythm, medication use, and overall health status.

RESULTS

The AF-free rates of group I and group II patients were statistically equivalent for both ablation groups at all evaluation time points. None of the 112 patients treated with endoscopic mitral valve repair and ablative therapy experienced a specific patient injury attributable to ablation; no ablated patients died in hospital following the procedure; there were no esophageal perforations and no coronary artery stenosis due to the ablations in either ablation group. The rate of patients without AF was 74% in group I and 82% in group II in the 6-month follow-up. The group I pacemaker implantation rate of 14% was significantly higher than non-ablated group (4.7%), but the group II rate of 5.9% observed did not differ significantly from the non-ablated group.

CONCLUSIONS

It was shown with our results that one succeeds with the en bloc-ablation in treating patients with different kinds of atrial fibrillation with concurrent intervention in the mitral valve reliably and with a high rate. The combination of this procedure with endocardial interventional ablation technologies can possibly develop to a promising strategy in the hybrid therapy of the isolated chronic atrial fibrillation as a standalone procedure.

Chylothorax and chylopericardium following mitral and tricuspid valve repairs and radiofrequency maze procedure

Surgical radiofrequency Maze procedure is a well-developed technology with an established safety profile. Clinical complications, albeit rare, have been described secondary to usage of unipolar radiofrequency devices. Bipolar radiofrequency devices have virtually eliminated the complications associated with unipolar devices, thereby combining safety with efficacy. We report a case of chylopericardial tamponade and chylothorax following radiofrequency Maze procedure using a bipolar device. 

The influence of age on atrial fibrillation recurrence after the maze procedure in patients with giant left atrium

OBJECTIVE

The presence of a giant left atrium (LA) is strongly associated with the recurrence of atrial fibrillation (AF) after the maze procedure. Therefore, we investigated the factors affecting the rhythm outcomes after the maze procedure in patients with a giant LA and AF-associated mitral valve disease to determine the best candidates for the maze procedure in this population.

METHODS

From January 1999 to December 2006, 224 patients with a giant LA (> 60 mm) underwent bi-atrial maze procedures combined with mitral valve surgery. Multivariate Cox regression analysis was performed to determine the risk factors for maze failure.

RESULTS

Follow-up was complete in all patients at a mean of 48.3 ± 28.0 months, during which 4 early and 9 late deaths occurred. Of the 218 early survivors, 24 had late AF recurrence. The 5-year AF-free rate was 87.1% ± 4.3% in patients 50 years or younger and 77.3% ± 4.1% in patients older than 50 years (P = .001). Univariate analysis showed that advanced patient age (> 50 years), a longer duration of AF, a fine AF pattern (wave length < 1 mm), and increased cardiothoracic ratio (> 60%) were associated with late AF recurrence. On multivariate analysis, advanced patient age was the only significant, independent risk factor for AF recurrence.

CONCLUSIONS

Although giant LA is known to be a predictor of poor outcomes after the maze procedure, younger patients had more favorable rhythm outcomes than older patients, as shown by the superior freedom from AF recurrence. A more aggressive surgical approach in younger patients might eliminate AF, even in the presence of a giant LA.

An overview of energy sources in clinical use for the ablation of atrial fibrillation

Recent years have seen many developments in the field of alternative energy sources for arrhythmia surgery. The impetus behind these advances is to replace the traditional, "cut-and-sew" Cox maze III procedure with lesion sets that are simpler, shorter, and safer but just as effective. There is demand for technology to make continuous, linear, transmural ablations reliably with a versatile energy source via an epicardial approach. This would make minimally invasive endoscopic surgical ablation of atrial fibrillation (AF) without cardiopulmonary bypass and with a closed chest feasible. These advances would shorten cardio-pulmonary bypass and improve outcomes in patients having surgical ablation and concomitant cardiac surgery. This review summarizes the technology behind alternative energy sources used to treat AF. Alternative energy sources include hypothermic sources (cryoablation) and hyperthermic sources (radiofrequency, microwave, laser, ultrasound). For each source, the biophysical background, mode of tissue injury, factors affecting lesion size, and advantages and complications are discussed.

Surgical ablation of atrial fibrillation: the Columbia Presbyterian experience

BACKGROUND

The Maze III procedure is an effective surgical treatment for atrial fibrillation (AF). However, it is not widely applied due to its complexity, increased operative times, and the risk of bleeding. Various energy sources have been introduced to simplify the traditional "cut and sew" approach.

METHODS

This study involves patients undergoing surgical atrial fibrillation ablation (SAFA) at a single institution from 1999 to 2005. Type of concomitant procedures, preoperative clinical characteristics, and chronicity of AF were evaluated in overall patient population. Parameters including surgical approach, lesion pattern, and energy source used were collected intraoperatively. Clinical outcomes examined were postoperative rhythm success, stroke, early mortality, and long-term survival.

RESULTS

Three hundred thirty-nine patients were identified. Three hundred twenty-eight (96.8%) patients had associated cardiac disease and underwent concomitant procedures; 75.8% of patients had persistent AF. Energy sources used were microwave (49.8%), radiofrequency (42.2%), and laser (8.0%). In 41.9% of cases a pulmonary vein encircling lesion was the only lesion created. Combination lesion sets were performed in the remaining cases. Rhythm success rates at 3, 6, 12, and 24 months were 74.1%, 68.2%, 74.5%, and 71.1%, respectively. Patients who underwent surgical removal of left atrial appendage by means of stapling or simple excision had no early postoperative stroke. Early mortality was 4.9%. Postoperative survival rates at 1, 3, and 5 years were 89.6%, 83.1%, and 78.0%.

CONCLUSIONS

Surgical ablation of atrial fibrillation is a safe and effective procedure in restoring sinus rhythm with excellent postoperative survival rates. Further advancements in the field will eventually result in minimally invasive procedures with higher success rates.

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.

An experimental sheep model used to develop an ablation procedure for chronic atrial fibrillation

BACKGROUND

Atrial fibrillation is the most common form of serious arrhythmia in humans. The therapeutic options offered are medical, surgical, and interventional. The surgical approach is justified in cases of atrial fibrillation already subjected to cardiac surgery for an associated organic heart disease such as a valvular or ischemic disease. A minimally invasive surgical approach is needed to extend the possibility of surgical treatment to patients with lone atrial fibrillation and those who cannot be treated by interventional procedures. This study aimed to use sheep as an experimental model in developing a minimally invasive surgical procedure for chronic atrial fibrillation therapy in humans.

METHODS

The investigation was conducted with 20 animals using a video-assisted thoracoscopic approach, in which a flexible microwave energy ablating probe was positioned on the epicardial surface encircling the pulmonary veins.

RESULTS

In 10 of the 20 animals, it was possible to encircle the pulmonary veins using the thoracoscopic approach in less than 3 h without major complications.

CONCLUSION

The epicardial ablation procedure using the thoracoscopic approach is feasible, safe, and reproducible.

Advances in Surgical Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia. It is associated with increased risks of death and stroke; most strokes in AF patients are thought to arise from thrombi in the left atrial appendage. Surgical ablation of AF includes excision of the left atrial appendage and is an effective means of treating this arrhythmia, with the classic Maze procedure curing AF in >90% of patients and virtually eliminating the risk of late stroke. 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. The majority of surgical ablation procedures have been performed in conjunction with mitral valve surgery, with 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. In addition, novel devices designed specifically for minimally invasive epicardial exclusion of the left atrial appendage will broaden the range of treatment options for patients with AF, possibly eliminating the need for anticoagulation in selected patients.

Current strategies in the surgical treatment of atrial fibrillation: review of the literature and Onze Lieve Vrouw Clinic's strategy

Atrial fibrillation is the most common rhythm disturbance in clinical practice. It is a major source of stroke and morbidity. Although the Cox maze procedure effectively eliminates atrial fibrillation in most patients, the procedure has not found widespread application. As a consequence, new operations that use alternative sources of energy, such as radiofrequency, microwave, cryothermy, laser, and ultrasound have emerged to surgically create lesion sets to treat atrial fibrillation. This article reviews the fundamentals and current strategies in the surgical treatment of atrial fibrillation.

Left Atrial Reduction Enhances Outcomes of Modified Maze Procedure for Permanent Atrial Fibrillation During Concomitant Mitral Surgery

BACKGROUND

Success of the maze procedure after mitral operations with large left atria and permanent atrial fibrillation remains suboptimal. Current technique variations tend to obscure the decision-making algorithm in these patients. A single energy-source approach for the surgical management of patients with large left atria and permanent atrial fibrillation is presented.

METHODS

From January 2003 to July 2005, 71 consecutive drug-resistant patients with permanent atrial fibrillation and left atrial enlargement who required mitral valve surgery underwent aggressive left atrial reduction combined with left-sided only irrigated radiofrequency unipolar maze. Left atrial dimensions were measured by transesophageal echo anterior-to-posterior leading edge-to-edge standardized protocol. There were 39 men (54.9%) and 32 women (45.1%), and their mean age was 71.9 +/- 9.5 years. Mean duration of atrial fibrillation was 49.3 +/- 58.0 months.

RESULTS

All patients underwent left atrial reduction with identical Cox-maze III pulmonary vein and appendage isolation including mitral annular connection, followed by appendage suture closure. Left atrial size was reduced from 6.7 +/- 1.2 cm to 4.3 +/- 0.6 cm (p = 0.001). Mitral valve repair was performed in 55 patients (76.1%) and replacement in 17 (23.9%). The 30-day mortality was 4.2% (3/71). Postoperative length of stay was 8.8 +/- 5.7 days, with 56 (82.4%) of 68 patients discharged in normal sinus rhythm. P-wave sinus rhythm was 93.8% between 7 and 12 months and 92.0% for patients with 1 year or more of follow-up.

CONCLUSIONS

Left atrial reduction combined with a left atrial only single energy-source radiofrequency maze procedure is an effective treatment for patients with permanent atrial fibrillation undergoing concomitant mitral operations.

Current Strategies in the Management of Atrial Fibrillation

Treatment of atrial fibrillation (AF) has been undergoing significant changes recently. This is due partly to different mechanisms proposed for persistent and permanent AF and partly due to the introduction of energy-based techniques, providing less invasive procedures. This article aims to review the mechanisms of AF leading to the changes in clinical practice and to review the results of surgery, energy-based, and percutaneous techniques. It is difficult to compare and contrast the results of reported series in the literature due to different definitions of AF; freedom from and recurrence of it. Furthermore, in most series it is difficult to distinguish results of surgery for lone AF and AF associated with valvular heart disease and coronary artery disease.

Surgical ablation as treatment for the elimination of atrial fibrillation: A meta-analysis

OBJECTIVE

The maze procedure is recognized as the most effective surgical treatment of atrial fibrillation. In the last few years, new surgical ablation techniques were developed involving the left atrium only and modifications of the maze procedure in ablating both atria. For this study, we evaluated the evidence regarding the effectiveness of the surgical ablation procedures (biatrial and left atrial) in reducing postoperative atrial fibrillation and subsequent survival.

METHODS

MEDLINE was searched for English-language studies using the terms "maze," "atrial fibrillation," and "surgical treatment" for 1995 through August 2005. Primary outcomes of interest were postoperative survival and postoperative freedom from atrial fibrillation. Survival data were collected at 1-, 2-, and 3-year intervals. Freedom from atrial fibrillation was collected at 3 months and at 1-, 2-, and 3-year intervals.

RESULTS

Sixty-nine studies were included in this analysis. Five thousand eight hundred eighty-five total patients were involved. Patients undergoing surgical ablation (range, 90.4-85.4) demonstrated significantly greater rates of freedom from atrial fibrillation compared with those seen in control patients (range, 47.2-60.9). Survival rates among patients with biatrial surgical procedures (range, 94.9-92.8) were similar to those who had left atrial procedures only (range, 93.9-89.4). However, patients undergoing biatrial ablation (range, 92.0-87.1 vs 86.1-73.4) demonstrated superior freedom from atrial fibrillation at all time points.

CONCLUSION

Biatrial ablation surgical procedures were more effective in controlling atrial fibrillation than procedures confined to the left atrium. To encourage the use of future meta-analysis within the surgical literature, we suggest the more frequent reporting of either through Kaplan-Meier survival analyses and the reporting of rates for specific time intervals.

Atrial Fibrillation Ablation: Reaching the Mainstream

INTRODUCTION AND AIMS

Ablation of atrial fibrillation (AF) has evolved rapidly in the decade since its inception. We aimed to review the results of this evolution as reflected in the published literature.

METHODS

Publications through 2005 were reviewed, and data included if there was information on the technique used, and follow-up of at least 6 months.

RESULTS

More than 23,000 patients met criteria for inclusion. There has been a steady improvement in reported outcomes (P<0.001). Variations on radiofrequency catheter ablation for pulmonary vein isolation result in apparent elimination ("cure") or improvement of AF in 75%, and surgical techniques are even better.

CONCLUSIONS

Catheter ablation of AF is now a mainstream procedure. Continuing technical advances are needed to achieve better results with more uniformity and reduced procedure times.

Mechanisms of Atrial Tachyarrhythmias Following Surgical Atrial Fibrillation Ablation

INTRODUCTION

Typical and atypical atrial flutters (AFLs) and atrial tachycardias (ATs) have been reported in patients with prior surgical atrial fibrillation ablation. The underlying mechanisms for this group of atrial tachyarrhythmias have not been well characterized and the efficacy of catheter ablation in their treatment is unknown.

METHODS AND RESULTS

Twenty patients (6 females) with a surface ECG diagnosis of AFL or AT following surgical atrial fibrillation ablation underwent 26 electrophysiology studies. Patients manifesting sustained, organized, and beat-by-beat reproducible atrial electrical activity underwent complete right and left atrial catheter mapping and catheter ablation. One patient had no inducible tachyarrhythmia, while 5 patients had nonmappable arrhythmias. Nineteen of the 31 potentially mappable atrial tachyarrhythmias were completely characterized in 14 patients. The underlying mechanisms were macro-reentrant left AFL (n = 9), focal left AT (n = 3), typical right AFL (n = 6), and atypical right AFL (n = 1). Of the 19 completely characterized atrial arrhythmias, catheter ablation was performed for 18, and the procedure was successful for 13 of these. After a mean follow-up of 15 +/- 10 months, 15 of 20 patients (75%) were in sinus rhythm including 10 of 13 patients (77%) with AT/flutter ablation. Ten patients, including 6 following ablation, were maintaining sinus rhythm without antiarrhythmic medications.

CONCLUSIONS

Patients with an ECG diagnosis of AFL or AT following surgical atrial fibrillation ablation may have multiple tachycardia mechanisms with the right or left atrium as the site of origin. Many of these rhythms may resolve with further maturation of surgical atrial fibrillation ablation (SAFA) lesions or be treatable with antiarrhythmic medication. However, persistent tachyarrhythmias can often be treated successfully with catheter mapping and ablation.

Radiofrequency pulmonary veins isolation of atrial fibrillation in patients undergoing mitral valve replacement

Introduction: Pulmonary veins isolation (PVI) is useful method in patients (pts) with mitral valve disease (MVD) and chronic atrial fibrillation (AF) during prosthetic valve implantation.

The aim of the study: To evaluate e.ectiveness of PVI in the treatment of AF in pt with MVD during valve implantation.

Material and methods: 45 pts (mean age 55 yrs) with AF were operated on for MVD.RF ablation around the pulmonary veins, a lesion between them and to the mitral annulus were performed. There were 44 prostheses implanted, 1 case of mitral valve annuloplasty, associated with tricuspid valve repair (5 pts), aorto-coronary bypass procedure (2 pts), ASD II closure (1 pt).

Results: SR was achieved in 2 (44,5%) pts, 21 (46,5%)pts were in AF, 4 (9%) pts needed pacing. No correlation between SR restoration and preoperative echocardiographic parameters, age, gender, NYHA functional class were found. In long-term follow-up 1 pt have reversed AF to SR spontaneously. There were 6 cases of paroxysmal AF,1 pt needed pacemaker implantation. 20 (44,5%) pts are in SR, 20 (44,5%) in AF, 5 (11%) in permanent pacing.

Conclusion: PVI with RF use is effective in restoring sinus rhythm in patients with chronic AF secondary to mitral valve disease.

Surgical treatment of atrial fibrillation using argon-based cryoablation during concomitant cardiac procedures

BACKGROUND

The development of ablative energy sources has simplified the surgical treatment of atrial fibrillation (AF) during concomitant cardiac procedures. We report our results using argon-based endocardial cryoablation for the treatment of AF in patients undergoing concomitant cardiac procedures.

METHODS AND RESULTS

Sixty-three patients with AF who were undergoing concomitant cardiac procedures had the same left atrial endocardial lesion set using a flexible argon-based cryoablative device. Mean age was 65.1+/-1.3 years. Sixty-two percent had permanent AF, whereas 38% had paroxysmal AF. Mean duration of AF was 30.5+/-4.8 months. Mean left atrial diameter was 5.5+/-0.1 cm. Mean ejection fraction was 45+/-1.4%. All endocardial lesions were performed for 1 minute once tissue temperature reached -40 degrees C. Follow-up echocardiograms were obtained to determine freedom from AF. Kaplan-Meier analysis demonstrated an 88.5% freedom from AF rate at 12 months. Ablation time was 16.8+/-0.6 minutes. There were no in-hospital deaths and no strokes. Twelve patients (19%) required postoperative permanent pacemaker placement.

CONCLUSIONS

Cryoablation using this flexible argon-based device for the treatment of AF during concomitant cardiac procedures was safe and effective, with 88.5% of patients free from AF at 12 months.

Surgical ablation of atrial fibrillation with off-pump, epicardial, high-intensity focused ultrasound: results of a multicenter trial

BACKGROUND

A simplified alternative to the Cox maze procedure to treat atrial fibrillation with epicardial high-intensity focused ultrasound was evaluated clinically, and the initial clinical results were assessed at the 6-month follow-up visit.

METHODS

From September 2002 through February 2004, 103 patients were prospectively enrolled in a multicenter study. Atrial fibrillation duration ranged from 6 to 240 months (mean, 44 months) and was permanent in 76 (74%) patients, paroxysmal in 22 (21%) patients, and persistent in 5 (5%) patients. All patients had concomitant operations, and ablation was performed epicardially on the beating heart before the concomitant procedure. The device automatically created a circumferential left atrial ablation around the pulmonary veins in an average of 10 minutes, and an additional mitral line was created epicardially in 35 (34%) patients with a handheld device by using the same technology.

RESULTS

No complications or deaths were device or procedure related. There were 4 (3.8%) early deaths and 2 late extracardiac deaths. The 6-month follow-up was complete in all survivors. At the 6-month visit, freedom from atrial fibrillation was 85% in the entire study group (80% in patients with permanent atrial fibrillation, 88% in the 35 patients who had the additional mitral line, and 100% in patients with paroxysmal atrial fibrillation). A pacemaker was implanted in 8 patients. Only the duration and type of atrial fibrillation significantly increased the risk of recurrence.

CONCLUSION

Epicardial, off-pump, beating-heart ablation with acoustic energy is safe and cures 80% of patients with permanent atrial fibrillation associated with long-standing structural heart 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.

Epicardial microwave application in chronic atrial fibrillation surgery

The search for alternative epicardial energy sources in the treatment of nonvalvular atrial fibrillation (AF) is a relatively new aspect of the evolving spectrum of Maze operations. We tested the hypothesis that epicardial microwave ablation produces identical results to those of the standard cryosurgical Maze. Fourteen consecutive patients with chronic AF underwent on-pump epicardial Maze procedures after routine cardiac surgery. The results were compared with those of 14 control patients selected from our Maze database of 280 patients. There were no differences in age, sex, cardiothoracic ratio, duration of AF, pump time, intensive care unit or hospital stays. The aortic cross clamp time with epicardial microwave was, however, shortened from 110 to 65 minutes (p=0.011). The recurrence rate of AF after discharge showed no significant difference between the two groups (14% vs. 15%, p=0.841). Epicardial microwave ablation might be a valuable alternative to the conventional cryosurgical Maze procedure, especially for those patients without associated mitral valve disease.

Surgical ablation of atrial fibrillation with a novel bipolar radiofrequency device

OBJECTIVE

When used for epicardial ablation, unipolar devices do not predictably yield transmural scars. Bipolar radiofrequency proved highly effective on the animal model, but clinical experience is still initial. We describe acute electrophysiologic findings and follow-up results of epicardial ablation with a novel bipolar radiofrequency device.

METHODS

A bipolar ablator was used to perform a simplified left atrial lesion set in 90 consecutive patients with atrial fibrillation undergoing open heart surgery. Pacing thresholds were assessed during surgery to validate 24 pulmonary vein encircling lines (12 patients). Follow-up was 100% complete.

RESULTS

In 67 of 90 patients (84%), mitral valve disease was the main indication to surgery. Atrial fibrillation was continuous in 74 patients (82%) and intermittent in 16 patients (18%). Pacing threshold assessment showed a complete conduction block in 22 of 24 pulmonary vein couples (92%) after a single ablation and in all patients after doubling of the encircling lines. No complications related to the ablation procedure were recorded. The sinus rhythm restoration rate was 79% at 3 months, 87% at 6 months, and 89% (17/18 patients) at 1 year. Postablation organized arrhythmias consisted in right atrial flutter in 2 patients (2%) and left atrial flutter in 6 patients (7%).

CONCLUSIONS

Epicardial ablation with bipolar radiofrequency grants acute transmurality. A simplified lesion set proved highly effective in eliminating atrial fibrillation at 1-year follow-up. Our data suggest that addition of a lesion to the mitral annulus is advisable to prevent left atrial flutter.

The Effect of Concomitant Radiofrequency Ablation and Surgical Technique (Repair Versus Replacement) on Release of Cardiac Biomarkers During Mitral Valve Surgery

All patients undergoing heart surgery experience a certain amount of nonspecific myocardial injury documented by the release of cardiac biomarkers and associated with poor outcome. We investigated the role of unipolar radiofrequency ablation of atrial fibrillation on the release of cardiac biomarkers in 71 patients undergoing mitral valve surgery and concomitant left atrial ablation case-matched with 71 patients undergoing isolated mitral surgery. The study was powered to detect a 3 ng/mL difference. There was no difference between the 2 groups in terms of cardiac troponin I (10 +/- 5.3 versus 12 + 10.4 ng/mL; P = 0.7) or creatine kinase-MB (50 +/- 21.8 versus 57 +/- 62.0 ng/mL; P = 0.5) release. Postoperative peak cardiac troponin I levels had univariate associations with the duration of cardiopulmonary bypass (P = 0.002) and aortic cross-clamping (P = 0.001) and with the surgical technique (15 +/- 12 ng/mL for mitral valve replacement versus 9 +/- 4.8 for mitral valve repair; P = 0.0007) at univariate analysis. Mitral valve replacement was the only independent predictor of postoperative peak release of cardiac troponin I identified with multivariate analysis (P = 0.005). Radiofrequency ablation of atrial fibrillation does not significantly increase cardiac biomarker release compared with isolated mitral surgery; mitral valve repair is associated with less release of cardiac biomarkers compared with mitral valve replacement.

Intraoperative Radiofrequency Ablation for the Treatment of Atrial Fibrillation During Concomitant Cardiac Surgery

BACKGROUND

Radiofrequency ablation has been recently introduced as an alternative to the surgical maze procedure to eliminate atrial fibrillation (AF). The purpose of this study was to examine the effectiveness of unipolar radiofrequency ablation in patients with AF undergoing open heart surgery.

METHODS

A retrospective review was performed on 54 patients undergoing radiofrequency ablation with concomitant cardiac operations from March 2002 through July 2003. Forty-two patients (77.8%) received left atrial ablation, and 12 (22.2%) received biatrial ablation.

RESULTS

Mean duration of preoperative AF was 46.3 +/- 44 months; 23 (42.6%) had AF 5 years or more, 32 (59.3%) had continuous AF, and 12 (22.6%) had a preoperative left atrial diameter of 6.0 cm or greater. At discharge, 33 patients (70.2%) were free from AF, 30 (62.5%) were in normal sinus rhythm, and 6 (12.7%) required a new pacemaker. Mid-term follow-up was available in 44 (93.6%) patients, with a median follow-up of 8.7 months (range, 3 to 22 months). At follow-up, 34 (77.3%) patients were free from AF. There were no significant differences in freedom from AF in patients with continuous versus intermittent AF or duration of 5 or greater years versus less than 5 years. In patients with isolated mitral valve surgery and radiofrequency ablation, 22 (88.0%) were free from AF compared with 12 (63.2%) with other operations (p = 0.074). In patients with left atrial diameter less than 6.0 cm, 30 (88.2%) were free from AF compared with 4 (40%) with left atrial diameter of 6.0 cm or greater (p = 0.006).

CONCLUSIONS

Radiofrequency ablation is an effective surgical option for the treatment of continuous or intermittent AF. The elimination of AF using radiofrequency ablation is most successful in patients undergoing isolated mitral valve surgery with preoperative left atrial diameter less than 6.0 cm.