Left atrial isolation associated with mitral valve operations

The Minimum Number of Ablation Lines for Complete Isolation of the Pulmonary Veins during Thoracoscopic Ablation for Atrial Fibrillation

Total thoracoscopic ablation has been recommended as a class IIa indication for atrial fibrillation. However, the optimal number of ablation lines for pulmonary vein isolation has not yet been proposed. This study aimed to report the minimum number of ablation lines required to achieve an intraoperative conduction block. This study included a total of 20 patients who underwent total thoracoscopic ablation from December 2020 to July 2021. The epicardial conduction block was checked after each ablation line of pulmonary vein antral clamping. The median age was 61 years old. The median duration of atrial fibrillation since the first diagnosis was 78 months. Pulmonary vein isolation with bidirectional conduction block was confirmed in 90% of patients. A median of six ablation lines around each pulmonary vein antrum were performed according to our protocol even after the conduction block was verified. The median number of ablations to achieve an exit block was two on the right side and 3.5 on the left side. We found that most conduction blocks were achieved within three ablations around the pulmonary vein antrum. Our results may provide evidence to reduce the number of unnecessary ablation lines in the future.

Left Atrial Isolation and Appendage Occlusion in Patients With Atrial Fibrillation at End-Stage Left Atrial Fibrotic Disease

[Figure: see text].

Surgical treatment of atrial fibrillation: a review

Atrial fibrillation is the most commonly sustained arrhythmia in man. While it affects millions of patients worldwide, its incidence will markedly increase with an aging population. Primary goals of AF therapy are to (1) reduce embolic complications, particularly stroke, (2) alleviate symptoms, and (3) prevent long-term heart remodelling. These have been proven to be a challenge as there are major limitations in our knowledge of the pathological and electrophysiological mechanisms underlying AF. Although advances continue to be made in the medical management of this condition, pharmacotherapy is often unsuccessful. Because of the high recurrence rate of AF despite antiarrhythmic drug therapy for maintenance of sinus rhythm and the adverse effects of these drugs, there has been growing interest in nonpharmacological strategies. Surgery for treatment of AF has been around for some time. The Cox-Maze procedure is the gold standard for the surgical treatment of atrial fibrillation and has more than 90% success in eliminating atrial fibrillation. Although the cut and sew maze is very effective, it has been superseded by newer operations that rely on alternate energy sources to create lines of conduction block. In addition, the evolution of improved ablation technology and instrumentation has facilitated the development of minimally invasive approaches. In this paper, the rationale for surgical ablation for atrial fibrillation and the different surgical techniques that were developed will be explored. In addition, it will detail the new approaches to surgical ablation of atrial fibrillation that employ alternate energy sources.

Cardima Surgical Ablation System: a novel tool for cardiac ablation in the treatment of atrial fibrillation

Atrial fibrillation is a pervasive and difficult heart rhythm problem for more than 3 million Americans. Patients are plagued by myriad symptoms and are exposed to the risk of stroke. Attempts to restore normal rhythm with drug therapy have been largely unsuccessful and the complications associated with long-term anticoagulation to reduce stroke risk are appreciable. Much interest has therefore developed in nonpharmacological treatments, such as ablation. At present, the optimal ablation device and technique have yet to be found. The Cardima Surgical Ablation System is a newly developed apparatus delivering radiofrequency energy to the outside of the beating heart within a shielded, lighted, irrigated, suction sheath. It advances the field of surgical ablation by addressing many of the shortcomings of older ablating devices, such as target fixation, controlled energy delivery, prevention of collateral tissue damage and device conformability. In this publication we present the specific advantages and disadvantages of the system, discuss its possible role in atrial fibrillation treatment and compare its characteristics with other currently available devices.

Incisional left atrial isolation for ablation of atrial fibrillation in mitral valve surgery

The renewed interest in surgical techniques for atrial fibrillation (AF) limited to the left atrium has risen the importance of the original technique of left atrial isolation by means of surgical incision. Transmurality of lesions and cost containment are strong elements to be appreciated in this technique.

Operative and Percutaneous Procedures for Cure of Atrial Fibrillation

The surgical maze procedure was the first successful curative procedure for atrial fibrillation. However it is a technically difficult procedure and has not been widely adopted. Subsequently, radiofrequency ablation has been used to replace the surgical incisions of the maze operation in new open-heart and percutaneous catheter based procedures. These procedures have an acceptable level of efficacy and safety, and should be considered for patients with problematic atrial fibrillation. This review summarises the development of these procedures, their current role in the treatment of atrial fibrillation, patient selection and after care.

Surgery for Atrial Fibrillation: A Worldwide Review

Maze procedure is highly effective in converting atrial fibrillation (AF) back to sinus rhythm and significantly prevents thromboembolism postoperatively. However, the procedure has not been widely performed by many surgeons, because of the technical demand and potential risk of complications of the procedure. During the past several years, the surgical strategy for AF has evolved dramatically and significantly. The evolution can be classified into two strategies: simplification of the lesion set and development of ablation devices. Isolation of the pulmonary veins with or without left atrial incisions has been shown to cure AF in selected patients. During the past decade, a number of ablation devices have been developed to replace the cut-and-sew lesions of the maze procedure and lessen the invasiveness of the procedure. The challenge in AF surgery is in the development and establishment of an off-pump thoracoscopic procedure in the patients with isolated AF. In addition to the development of ablation devices, intraoperative electrophysiological assessment of the triggers and substrates of AF for a step-by-step tailored approach and verification of conduction block over the ablation line should be established to accomplish a high success rate for AF.

Linear cryoablation of the left atrium versus pulmonary vein cryoisolation in patients with permanent atrial fibrillation and valvular heart disease: correlation of electroanatomic mapping and long-term clinical results

BACKGROUND

The aim of this study was to clarify the role of pulmonary vein isolation (PVI) alone versus left atrial linear lesions in the treatment of permanent atrial fibrillation (AF) in patients with left atrial dilatation and valvular disease. The primary end point was to assess the persistence of sinus rhythm (SR) off antiarrhythmic drugs (AADs) at 2-year follow-up and to correlate clinical outcome with surgical results validated with electroanatomic mapping (EAM).

METHODS AND RESULTS

A total of 105 patients with permanent AF undergoing valve surgery were assigned to 3 different groups: in groups "U" and "7," left atrial linear cryoablation was performed, whereas in group "PV" patients, anatomic cryoisolation of pulmonary veins only was performed. In groups U and 7, SR was achieved in 57% of patients, whereas it was achieved in 20% of PV patients during 2-year follow-up. In the first 51 patients, the ablation schemes were validated with EAM. The EAM showed that the U lesion was never obtained: in 59% of these patients, a complete 7 lesion was achieved instead; in the 7 group, a complete 7 lesion was present in 65% of patients, whereas a complete PVI was obtained in 71% of patients. Considering patients in whom a complete 7 lesion was demonstrated with the EAM, SR without AADs was achieved in 86% of patients, whereas only 25% of patients with complete PVI were in SR without AADs.

CONCLUSIONS

In patients with permanent AF, left atrial dilatation and valvular heart disease linear lesions in the posterior region of the left atrium are more effective than PVI alone. With cryoablation, the surgical intent is fulfilled in only approximately 65% of the cases. Knowing the real anatomic and electrophysiological effects of surgical ablation is necessary to correctly interpret the clinical outcome.

Pulmonary vein isolation by microwave energy ablation in patients with permanent atrial fibrillation

BACKGROUND

Atrial fibrillation is associated with significant morbidity and mortality. Microwave energy ablation (MW) is a new option for surgical treatment of permanent atrial fibrillation (pAF). We present our experience with surgical treatment of mitral valve disease (MVD), coronary artery disease (CAD), and aortic valve disease (AVD) and microwave ablation in patients with pAF.

METHODS

In 202 consecutive patients (100 female, 102 male, age 68.3 +/- 8.1 years from 30.4 to 83.5 years, ejection fraction 25-80%, left atrial diameter 56 +/- 9.1 mm from 30 to 102 mm) with an indication for a cardiosurgical intervention, pAF was documented for 6.8 +/- 9.1 years. MW was performed using two different lesion concepts. In the first 140 patients we used an ablation line starting at the posterior mitral valve annulus and incorporated the interior of all pulmonary veins. After the first 137 patients we switched to a different ablation line concept. Starting at the posterior mitral valve the annulus ablation line additionally included the left atrial appendix. Another ablation circle around the pulmonary veins of both sides was created and both circles were connected. If opening of the right atrium was necessary additional isthmus ablation was performed.

RESULTS

Survival rate was 98.5%. There were no ablation-related complications. In the 6-month follow-up 87 patients were in sinus rhythm (65%), in the 1-year follow-up 74 patients were in SR (62.2%).

CONCLUSIONS

Microwave ablation is a safe and efficient method for surgical treatment of pAF in patients with a concomitant cardiosurgical procedure. The short duration for this additional procedure and easy application has made this procedure the method of choice in our institution for treatment of pAF in patients with cardiosurgical operations.

Factors Predicting Success in Cryoablation of the Pulmonary Veins in Patients With Chronic Atrial Fibrillation

BACKGROUND

This study was designed to investigate the factors predicting maintenance of sinus rhythm (SR) in patients with chronic atrial fibrillation (AF) undergoing cryoablation of the pulmonary veins (PV-cryo) during cardiac surgery.

METHODS AND RESULTS

Seventy-seven patients with AF undergoing PV-cryo were recruited and divided into 2 groups based on whether they were able to maintain SR at discharge. The duration of AF (AF-D), left atrial dimension (LAd), and the average of the peak left atrial appendage outflow velocities (LAA-V) before surgery were determined for both groups. Group SR consisted of 54 patients (70%), and group AF consisted of 23 patients (30%). All patients with an AF-D <or=3 years, LAd <45 mm and LAA-V >40 cm/s were in group SR and all those with an AF-D >10 years and LAd >or=65 mm were in group AF. Only 71% of patients with a LAA-V <or=20 cm/s were in group AF.

CONCLUSIONS

Restoration of AF to SR by PV-cryo can be predicted from a knowledge of the AF-D, LAd and LAA-V.

Atrial compartment operation for atrial fibrillation: to isolate the left atrium or not?

BACKGROUND

The atrial compartment operation was designed to convert atrial fibrillation (AF) to sinus rhythm with intentional preservation of the electrical connection between adjacent atrial compartments. However, incidental left atrial isolation was observed in some patients. This study compared the long-term clinical outcomes of left atrial isolation for AF with those with right and left atrial connection.

METHODS

Twenty patients with mitral valve disease and chronic AF who underwent atrial compartment operation with successful sinus conversion were studied. Left atrial isolation was documented by local electrogram recording. When there were no signs of electrical connection between the left atrium and the rest of the heart, either during sinus rhythm or during stimulation from various atrial compartments, left atrial isolation was confirmed. All patients were followed by electrocardiogram and echocardiogram serial recordings. Clinical signs and symptoms of cardiac performance and thromboembolism were also examined.

RESULTS

Seven patients showed an isolated left atrium and 13 patients had electrical connection between the right and left atria. The age, gender, AF duration, and underlying disease were not different between the two groups of patients. During a mean follow-up period of 66 +/- 15 months, none of the patients with left atrial isolation showed recurrence of AF, although one experienced paroxysmal atrial flutter. However, 8 of the 13 patients with right and left atrial connection experienced recurrent atrial flutter/fibrillation (6 atrial flutter and 5 AF) (p = 0.058). The propensity for recurrent atrial flutter/fibrillation in these patients may be related to the conduction delay between the two atrial compartments, measured at 142 +/- 48 ms. At the end of the follow-up period, all patients with left atrial isolation remained in normal sinus rhythm without antiarrhythmic drugs. Of the patients who had right and left atrial connection, 2 developed sustained AF and 1 developed atrial flutter. Patients with left atrial isolation showed a decreased transmitral "A" flow compared with those with right and left atrial connection. Postoperative left atrial diameter and clinical functional class did not differ between patients with and without left atrial isolation. The incidence of embolization observed in both treatment groups did not differ significantly: 14% (1/7) in patients with left atrial isolation and 8% (1/13) in patients with right and left atrial connection (p > 0.05 between the groups).

CONCLUSIONS

Left atrial isolation confers a better arrhythmia outcome but at the expense of poorer mechanical performance as compared with preserved electrical connection between the two atria. Nonetheless, all patients remain at risk for systemic embolization. Therefore, modifications of current surgical incisions for AF are needed.

Clinical histopathology and ultrastructural analysis of myocardium following microwave energy ablation

OBJECTIVE

Due to weaknesses of conventional modes for treating atrial fibrillation (AF), surgical energy ablation methods and tools to cure AF have been under rapid development. One of these methods, microwave energy, is beginning to be applied clinically. The purpose of this study was to examine histology and ultrastructure of lesions produced by microwave energy in the myocardium.

METHODS

Fifteen consecutive patients underwent surgical microwave energy ablation (Microwave Ablation System with FLEX 4 probe, AFx Inc., Fremont, CA) concomitant to a valve procedure. Epicardial ablation was carried out on the beating normothermic heart prior to performing the valve procedure. Two tissue specimens (1cm(2)) were obtained from each patient; one from the lesion site (right appendage) and the other from an adjacent, non-ablated site, which was used as control. Tissue samples were fixed and stained as appropriate for histological and ultrastructural analysis.

RESULTS

All ablated samples revealed observable microscopic alteration, including loss of nuclei, foci of coagulative necrosis or induced irregular bands of contraction. Ultrastructurally, ablated cells demonstrated architectural disarray, loss of contractile filaments, mitochondrial swelling and focal interruption of plasma membrane.

CONCLUSIONS

Histologic appearance of lesions created by epicardial microwave energy ablation was consistent over tissue samples, although acute findings demonstrated differences from cryoablation. In most of the cases, lesions were transmural, as was demonstrated by loss of cellular viability throughout the depth of tissue specimens.

Characterization of left atrial activation in the intact human heart

BACKGROUND

The patterns of activation of the human left atrium (LA), how they relate to atrial myocardial architecture, and their role in arrhythmogenesis remain largely unknown.

METHODS AND RESULTS

Left atrial endocardial activation was mapped in 19 patients with a percutaneous noncontact mapping system. Earliest endocardial breakthrough during sinus rhythm (SR) occurred more frequently in the septal (63%, principally posteroseptal) than anterosuperior (37%) LA and varied little with isoproterenol or high right atrial pacing rate. Regardless of site of breakthrough, LA activation was characterized in all patients by propagation around a variably complete line of functional conduction block, descending on the posterior wall from the roof, passing between the ostia of the superior and then inferior pulmonary veins (PVs) before turning septally, passing below the oval fossa, and merging further anteriorly with the septal mitral annulus. Examination of the myocardial architecture in 10 normal adult postmortem hearts revealed an abrupt change in subendocardial fiber orientation along a line following the same course. During episodes of focal initiation of atrial fibrillation (AF), interaction was observed between wavefronts entering the LA from PVs and this functional line of conduction block that resulted in LA macroreentry or formation of daughter wavefronts.

CONCLUSIONS

The LA endocardium has complex but characteristic patterns of activation during sinus rhythm, pacing, and AF initiation by PV ectopy that are determined largely by the functional properties of atrial musculature. These findings have important implications for both pacing and ablative strategies for the prevention of initiation of AF.

Combined atrial fibrillation and mitral valve surgery using microwave technology

Atrial fibrillation is associated with a significant morbidity and mortality and is typically related to patients with mitral valve disease. Microwave ablation is a new option for surgical treatment of chronic atrial fibrillation. We present our experience with surgical treatment of mitral valve disease and microwave ablation in patients with chronic atrial fibrillation. In 105 patients (73 women, 32 men, 68.6 +/- 8 years of age from 45 to 83 years, ejection fraction 28% to 80%, left atrial diameter 56 +/- 9.1 mm from 35 to 97 mm) with mitral valve disease, chronic atrial fibrillation was documented for 8.6 +/- 6.8 years. Microwave ablation was performed using a continuous ablation line starting at the posterior mitral valve annulus and incorporating the interior of all pulmonary veins. In 33 patients, mitral valve reconstruction was performed. Ten patients received biologic valve replacement; 3 of them got a stentless quattro mitral valve prosthesis. Survival rate was 99.1% (n = 104). In the 6-month follow-up, 42 of 69 patients were in sinus rhythm (61%); in the 1-year follow-up, 37 of 64 patients were in sinus rhythm (57.8%). Microwave ablation is a safe and efficient method for surgical treatment of chronic atrial fibrillation in patients with mitral valve disease.

Combined atrial fibrillation and mitral valve surgery using radiofrequency technology

Recently, intraoperative radiofrequency ablation of the left atrium combined with mitral valve surgery has become widely used. In our center, 30 patients underwent this combined procedure; median sternotomy was used in 16 patients, and port access was used in 14 patients. At hospital discharge, 18 patients (60%) were no longer in atrial fibrillation, and at 6 months, 19 patients (65%) remained in sinus rhythm. All sinus rhythm patients had a well-defined transmitral A wave detectable by echocardiography. One patient sustained a major stroke. Two patients required pacemaker implantation. Such encouraging preliminary results have triggered worldwide interest in the percutaneous and surgical treatment of atrial fibrillation. However, the excellent long-term results with the classic Cox-Maze III operation have not yet been achieved with these newer approaches. Further basic and clinical research is required before a predictable simple and safe technique can be introduced as a new standard for the surgical treatment of atrial fibrillation in patients with or without structural heart disease.

Simple surgical isolation of pulmonary veins for treating secondary atrial fibrillation in mitral valve disease

BACKGROUND

Chronic atrial fibrillation (AF) due to mitral valve disease has been successfully treated by surgery. We performed a study to evaluate the effectiveness of a surgical method of simple pulmonary vein isolation (PVI) without radiofrequency or cryoablation in the restoration of sinus rhythm in a group of patients.

METHODS

Fifteen patients were operated on for mitral valve disease and chronic AF. The technique consists basically of a circumferential incision excluding the pulmonary vein ostia from the left atrium.

RESULTS

Sinus rhythm was achieved in 92.3% of the patients at 6-month follow-up. Echocardiograms 2 months after surgery showed a mean decrease of 1.1 cm in left atrial size. Effective atrial ejection was reestablished in all patients in whom sinus rhythm was achieved (mean LA ejection fraction 41% +/- 14%). Twenty-four hour Holter recordings did not show episodes of paroxysmal atrial fibrillation in any patients. Four patients had isolated episodes of ventricular ectopic beats. Stress electrocardiograms showed mean maximal ventricular response was 64% +/- 11% and 73% +/- 9% of predicted value at 2 and 6 months, respectively. All patients had improved NYHA functional class after surgery; 74% of patients were in NYHA functional class I at 6 months compared with 13.3% preoperatively.

CONCLUSIONS

Pulmonary vein isolation without the use of radiofrequency or cryoablation is effective in restoring sinus rhythm in patients with chronic AF secondary to mitral valve disease. Based on simple surgical incisions, this technique is more advantageous than others requiring additional instrumentation.

Clinical analysis of results of a simple left atrial procedure for chronic atrial fibrillation

BACKGROUND

We have performed a simple left atrial procedure for eliminating chronic atrial fibrillation (AF) associated with mitral valve disease. This article analyzes the midterm results of this procedure.

METHODS

Thirty-two patients were enrolled in this study concomitant with mitral valve operations. Patients were divided into two groups (AF- and AF+). We examined the efficacy of this operation and atrial function for more than 12 months of follow-up.

RESULTS

In a total of 98.5 patient years of follow-up, AF was absent 3 years after operation in 74%. Of preoperative and intraoperative variables, only long duration o

Interatrial conduction of atrial tachycardia in heart transplant recipients: potential pathophysiology

Surgical suture lines formed at the site of anastamosis have been considered to be electrically inert and thus present a line of block to conduction. However, a number of reports have suggested that conduction is occasionally possible across suture lines. Most of these cases have reported conduction between donor and recipient atria following cardiac transplantation. We report an illustrative case successfully treated with radiofrequency ablation, and present pathology findings that may give insight into the pathophysiology.

Mini-maze suffices as adjunct to mitral valve surgery in patients with preoperative atrial fibrillation

INTRODUCTION

After mitral valve (MV) surgery, preoperative atrial fibrillation (AF) often recurs while cardioversion therapy generally fails. Additional Cox maze surgery improves postoperative arrhythmia outcome, but the extensive nature of such an approach limits general appliance. We investigated the clinical outcome of a simplified, less extensive Cox maze procedure ("mini-maze") as adjunct to MV surgery.

METHODS AND RESULTS

Thirteen patients with MV disease and preoperative AF were treated with combined surgery (group 1). Nine control patients without previous AF underwent isolated MV surgery (group 2). We retrospectively compared the results to findings in 23 patients with preoperative AF who had undergone isolated MV surgery (group 3). In group 1, mini-maze took an additional 46 minutes of perfusion time. One 75-year-old patient died of postoperative multiple organ failure. Seven patients showed spontaneously converting (within 2 months) postoperative AF. After 1 year, 82% were in sinus rhythm (SR). No sinus node dysfunction was observed. In group 2, all patients were in SR after 1 year. In group 3, only 53% were in SR after 1 year, despite serial cardioversion and antiarrhythmic drug therapy. Exercise tolerance and heart rate were comparable for groups 1 and 2. Left atrial function was present in all but one patient in group 1 and in all patients in group 2 (after MV reconstruction).

CONCLUSION

Adding a relatively simple mini-maze to MV surgery improves arrhythmia outcome in patients with preoperative AF without introducing sinus node dysfunction or persistent absence of left atrial function. The results of this type of combined surgery are encouraging and deserve further attention.

Endocardial and epicardial radiofrequency ablation in the treatment of atrial fibrillation with a new intra-operative device

OBJECTIVE

Atrial fibrillation has been a difficult problem to solve in many surgical patients, especially in those with mitral valve pathology. This study evaluates the results of endocardial and epicardial radiofrequency ablation with a new intra-operative device in the treatment of atrial fibrillation.

METHODS

We operated on 65 patients with atrial fibrillation, 58 of which had concomitant mitral surgery. Atrial fibrillation was chronic (over 1 year) in 46 patients (group A) and paroxysmal or recent onset in 12 (group B). Group C had lone atrial fibrillation (two), concomitant coronary artery disease (four) or a sarcoma (one). Bilateral pulmonary vein isolation with a new intra-operative device was performed through multiple dry lesions in all patients. Groups A and B had endocardial applications at 70 degrees C during 60 s and group C had epicardial applications at 75 degrees C. Three group C patients had epicardial applications off pump. Atrial wall biopsies were performed in nine patients from groups A and B.

RESULTS

There were no serious post-operative complications. At 1 month follow-up 54% of all patients were out of atrial fibrillation and 34% were in normal sinus rhythm with bilateral atrial contraction (Santa Crus Score 4). At 6 months follow-up, in spite of some crossover of patients among groups, similar results were obtained. The success of the procedure was 69% (Santa Crus scores 3 and 4) in mitral patients with a left atrial volume smaller than 200 cm(3). Preliminary data on the transmurality of the lesions is presented. The patients submitted to epicardial radiofrequency ablation (group C) have satisfactory results at 1 month (six out of seven were out of AF).

CONCLUSIONS

Both endocardial and epicardial RF applications are simple and quick to perform and do not pose an additional risk for most patients. Furthermore we believe that it is possible to perform bilateral epicardial radiofrequency ablation of the pulmonary veins without cardiopulmonary bypass. Further refinements of the technique are needed to assure transmurality of all lesions and better results.

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.

Mitral valve surgery and atrial fibrillation: is atrial fibrillation surgery also needed?

OBJECTIVE

Atrial fibrillation (AF) persisting after mitral valve surgery reduces survival due to heart failure and thrombo-embolisms, and impairs quality of life. Arrhythmia surgery for AF shows today very satisfying results and therefore mitral valve surgery with AF surgery appears appealing. This study explores whether combined surgery in view of today's results of mitral valve surgery is indicated.

METHODS AND RESULTS

An outcome analysis of the arrhythmia outcome of patients undergoing exclusive mitral valve surgery with or without tricuspid repair was done. Preoperative baseline characteristics including arrhythmia pattern, surgical methods and follow-up findings were reviewed. Postoperative management of AF was not protocolized. Between 1990 and 1993, 162 consecutive patients underwent mitral valve surgery; follow-up was a mean of 3.3+/-1.9 years. In-hospital and late mortality were 1 and 9%, respectively. Sinus rhythm was preserved in 40 of 57 (70%) patients with preoperative sinus rhythm whereas AF persisted in 58 of 68 (85%) of patients with preoperative chronic AF (>1 year present). Sinus rhythm without AF was observed in 10 of 29 (34%) patients with preoperative paroxysmal AF. The 4-year Kaplan-Meier survival did not differ between patients with preoperative sinus rhythm (95.2%), paroxysmal AF (89.2%) and chronic AF (82.9%) but AF persisting after surgery tended to determine survival (P=0.05). Gender, age and right ventricular pressure and tricuspid valve repair were risk factors for postoperative recurrence of AF in patients with sinus rhythm at discharge, relative risk 0.35, 1.06, 1. 04 and 2.9, respectively.

CONCLUSION

Current mitral valve surgery with or without tricuspid valve repair does not eliminate preoperative paroxysmal or chronic AF. Secondly, because preoperative AF did not determine survival after mitral valve surgery, whereas postoperatively persisting AF was weakly associated with survival, atrial arrhythmia surgery primarily aims to reduce morbidity due to AF. Some characteristics can identify patients with increased propensity for persisting AF after surgery. Randomized studies of AF surgery are needed to identify suitable candidates for combined surgery.

Results of maze surgery for lone paroxysmal atrial fibrillation

BACKGROUND

If drug refractoriness to paroxysmal atrial fibrillation (PAF) occurs, arrhythmia surgery that involves channelling and the exclusion of specific atrial areas can abolish atrial fibrillation. The purpose of this study was to establish the effectiveness and safety of maze III surgery to abolish PAF.

METHODS AND RESULTS

Surgery was performed in 41 selected patients who had long-standing, symptomatic, drug-refractory, lone PAF. At discharge, 35 patients (85%) were arrhythmia free, and 6 patients (15%) showed PAF and paroxysmal atrial tachycardia. Death or stroke did not occur during a mean follow-up of 31+/-16 months. At the end of follow-up, 39 patients (95%) had no PAF; however, in 2 patients (5%), PAF persisted and eventually required His bundle ablation and pacing. Three months after surgery, nodal escape rhythm was observed in only 1 patient, whereas sick-sinus syndrome emerged late after surgery in 2 patients. Antiarrhythmic drugs were used in 20% of patients during follow-up. The quality of life improved markedly after surgery and remained unchanged afterward. Echocardiographic findings did not alter, but exercise capacity increased.

CONCLUSIONS

This pilot study demonstrates the effectiveness and safety of maze III surgery for lone PAF. In patients without sick-sinus syndrome, this intervention offers a sensible alternative to His bundle ablation and lifelong pacemaker dependency.

Intraoperative map guided operation for atrial fibrillation due to mitral valve disease

BACKGROUND

This study was designed to determine if intraoperative atrial activation mapping facilitates operations for chronic atrial fibrillation associated with mitral valve disease.

METHODS

Surgical treatment guided by intraoperative electrophysiologic mapping was performed in 12 patients with chronic atrial fibrillation associated with isolated mitral valve disease. In 10 of 12 patients, regular and repetitive activation (cycle length ranged from 118 to 210 msec) originated in the left atrial appendage and/or orifice of the left pulmonary vein. In the remaining 2 patients, dominant repetitive activation and sporadic complex activation were alternately observed in the left atrium. However, the activation sequence of the right atrium was extremely complex and chaotic.

RESULTS

On the basis of intraoperative mapping, surgical procedures, including resection of the left atrial appendage and/or cryoablation of the orifice of the left pulmonary vein, were applied on the breakthrough site of the repetitive activation. No surgical procedure was performed on the right atrium in 11 patients. Ten of 12 patients (83%) have maintained sinus rhythm for 6 to 40 months (average 24.8 months) after operation.

CONCLUSIONS

In the majority of the patients with isolated mitral valve disease, the left atrium acts as an electrical driving chamber for chronic atrial fibrillation. Computerized intraoperative mapping should guide surgeons in determining the appropriate surgical procedure for chronic atrial fibrillation.

Catheter ablation of chronic atrial fibrillation targeting the reinitiating triggers

INTRODUCTION

We assessed the mode of reinitiation of atrial fibrillation (AF) after cardioversion and the efficacy of ablating these foci of reinitiation in patients with chronic AF.

METHODS AND RESULTS

Fifteen patients, 7 with structural heart disease, underwent mapping and catheter ablation of drug-resistant AF documented to be persistent for 5 +/- 4 months. In all patients, cardioversion was followed by documentation of P on T atrial ectopy and early recurrence, which allowed mapping of the reinitiating trigger or the source of ectopy. Radiofrequency (RF) ablation was performed at pulmonary vein (PV) ostia using a target temperature of 50 degrees C and a power limit of 30 to 40 W, with the endpoint being interruption of all local muscle conduction. A total of 32 arrhythmogenic PVs and 2 atrial foci (left septum and left appendage) were identified: 1, 2, and 3 or 4 PVs in 5, 3, and 6 patients. RF applications at the ostial perimeter resulted in progressively increasing delay, followed by abolition of PV potentials in 8, but potentials persisted in 6. A single ablation session was performed in 7 patients and 8 underwent two or three sessions because of recurrence of AF; ablation was directed at the same source due to recovery of local PV potential or at a different PV. No PV stenosis was noted either acutely or at repeated follow-up angiograms. Nine patients (60%) were in stable sinus rhythm without antiarrhythmic drugs at follow-up of 11 +/- 8 months. Anticoagulants were interrupted in 7 patients.

CONCLUSION

PVs are the dominant triggers reinitiating chronic AF in this patient population. Elimination of PV potentials by ostial RF applications results in stable sinus rhythm in 60%. A larger group and longer follow-up are needed to investigate further the role of trigger ablation in curative therapy for chronic AF.

Treatment of atrial fibrillation using the Maze procedure: the Japanese experience

The results of a questionnaire survey show that surgical treatment for atrial fibrillation (AF) has been performed in more than 2,500 patients in Japan. The methods of treatment used were the Cox-Maze-II procedure, the Cox-Maze-III procedure, the Kosakai-Maze procedure, the left atrial Maze procedure, the right atrial Maze procedure, compartment operation, radial operation, and other modifications. The success rates of the right atrial Maze procedure and compartment operation for AF associated with congenital heart disease were approximately 50%. These success rates were significantly lower than those of the other procedures (P < .005), which were more than 70%. Among the latter procedures, there was no significant difference in success rate. In the author's experience, atrial tachycardias caused by micro-re-entries or acceleration of automaticities were seen in approximately 50% of unsuccessful cases. Any type of Maze procedure can be used to cure atrial arrhythmia that is caused by macro-reentries alone. In the future it will be very important to establish indications for the Maze procedure and methods of simplifying the operation.

Surgery for atrial fibrillation using radiofrequency catheter ablation: assessment of results at one year

OBJECTIVE

The results obtained in 43 patients using direct intraoperative radiofrequency catheter ablation, as an alternative to surgical incisions, to perform atrial fibrillation surgery, are presented.

METHODS

Forty-three patients with ages ranging from 43 to 74 years (x = 59), with chronic atrial fibrillation with an average duration 6+/-5 years were operated. Eleven patients suffered from clinically relevant tachyarrythmia and eight had previous thromboembolic events. All but one patient had concomitant mitral valve surgery. Direct intraoperative radiofrequency catheter ablation was used to perform endocardial bilateral isolation of the pulmonary veins from the left atrium.

RESULTS

There were no local or general complications, namely bleeding or thromboembolic events. Of the 33 patients with more than 3 months of follow-up, 36% remained in atrial fibrillation (Santa Cruz score 0); 30% had Score 4; 18% had Score 3; 6% had Score 2; 9% had Score 1.

CONCLUSIONS

We conclude that the use of intraoperative radiofrequency catheter ablation is fast and safe. Presently, this is our method of choice for surgical treatment of atrial fibrillation in mitral patients.

Wavelength and conduction inhomogeneity in each atrium in patients with isolated mitral valve disease and atrial fibrillation

INTRODUCTION

Patients with mitral valve disease frequently have atrial fibrillation (AF), and the left atrium is presumed to be the primary atrium that develops AF. However, it is still not clear whether the electrophysiologic abnormalities responsible for AF are confined to the left atrium in this subset of patients.

METHODS AND RESULTS

To examine the AF vulnerability of each atrium, we measured the wavelength and inhomogeneity of the conduction at the lateral right atrium, lateral left atrium, and Bachmann's bundle after defibrillation of AF in seven patients undergoing the maze procedure and mitral valve surgery for AF and isolated mitral valve disease, respectively (AF group). The data were compared with five coronary surgery patients in sinus rhythm (SR group). The wavelength in the AF group was significantly shorter (P < 0.05) than in the SR group not only at the lateral left atrium (225 +/- 62 vs 285 +/- 36 mm) but also at the lateral right atrium (214 +/- 54 vs 254 +/- 34 mm). The variation coefficient of the local maximum activation phase difference in the AF group (1.9 +/- 0.8 at the right atrium, 2.1 +/- 0.8 at the lateral left atrium, and 2.0 +/- 0.6 at Bachmann's bundle) was significantly greater (P < 0.05) than in the SR group at all atrial regions.

CONCLUSION

AF vulnerability was not confined to the left atrium immediately after defibrillation in AF patients with isolated mitral valve disease. Electrical remodeling resulting from perpetuation of AF, pathological changes extending to the right atrium, geometric changes caused by the atrial interactions occurring across the interatrial septum, or a combination of these may explain the results.

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.

Pharmacologic cardioversion of chronic atrial fibrillation in the goat by class IA, IC, and III drugs: a comparison between hydroquinidine, cibenzoline, flecainide, and d-sotalol

INTRODUCTION

Recently, we reported that repetitive induction of atrial fibrillation (AF) in the goat causes electrical remodeling of the atria leading to the development of sustained AF. The aim of the present study was to compare Class IA, IC, and III drugs in their ability to cardiovert chronic AF in remodeled atria.

METHODS AND RESULTS

In 16 goats with sustained AF, hydroquinidine (HQ), cibenzoline (Ci), flecainide (FI), and d-sotalol (dS) were infused. HQ, Ci, Fl, and dS restored sinus rhythm (SR) in 83%, 91%, 67%, and 92% of the cases, while adverse drug effects occurred in 17%, 36%, 56%, and 8%. Prior to restoration of SR, AF cycle length prolonged by 68%, 103%, 53%, and 20%, respectively. The QRS width increased by 14%, 64%, and 58% (HQ, Ci, and Fl), and remained unchanged by administration of dS. RR intervals were slightly prolonged by HQ, Ci, and Fl, and markedly prolonged by dS (48%). The QT interval was moderately prolonged by HQ, Ci, and Fl, and considerably by dS (34%). QTc was only slightly prolonged by each of the drugs. Directly after cardioversion of AF, the atrial refractory period was 87+/-29 (HQ), 119+/-32 (Ci), 66+/-10 (Fl), and 73+/-18 msec (dS) (control: 146+/-18 msec). Atrial conduction velocity was 85+/-6, 71+/-11, 86+/-12, and 110+/-11 cm/sec compared with a control value of 116+/-10 cm/sec. Because directly after cardioversion the atrial wavelength was still very short (5.7 to 8.4 cm), the vulnerability for AF was still very high, and a single premature beat reinduced AF in 71% (Ci) to 100% (HQ, Fl, and dS) of the cases.

CONCLUSION

In a goat model of sustained AF, Class IA, IC, and III drugs restored sinus rhythm in 67% to 92% of the cases. However, after cardioversion, the atrial wavelength was still abnormally short, and AF was readily inducible in 71% to 100% of the cases.

Intraoperative map-guided operation for chronic atrial fibrillation

Intraoperative map-guided cryoablation for chronic atrial fibrillation and coronary artery bypass grafting were simultaneously performed in a 55-year-old man. Computerized atrial mapping revealed that regular and repetitive electrical discharges originated in the left atrial appendage. Without opening the left atrium, we successfully ablated atrial fibrillation with cryoablation on the epicardium of the left atrial appendage. Thus, intraoperative mapping should facilitate operations for atrial fibrillation.

Catheter ablation of atrioatrial conduction as a cure for atrial arrhythmia after orthotopic heart transplantation

OBJECTIVES

We present three patients in whom atrial arrhythmia was treated by ablation of electrical conduction across a surgical suture line.

BACKGROUND

Conduction across the suture line separating the donor and native right atria has recently been described after orthotopic heart transplantation.

METHODS

Mapping and pacing of both grafted and recipient right atrium was performed to assess the relation between both atria and its relevance to clinical arrhythmia, prior to successful radiofrequency at the site of electrical communication.

RESULTS

In cases 1 and 3, atrioatrial conduction was bidirectional. In both, two types of P waves were observed during sinus rhythm. In case 2, conduction from the recipient to the grafted atrium yielded a very particular surface ECG pattern of atrial extrasystole. The block being unidirectional, the recipient atrial sinus rhythm was not perturbed and behaved like an atrial parasystole. Ablation was performed during sinus rhythm in case 1, recipient right atrial pacing in case 2 and grafted right atrial pacing in case 3 at the site with the shortest conduction time to the other tissue. At the successful ablation site multiple component potentials were recorded. Respectively, 1, 4 and 2 radiofrequency pulses were followed by total atrioatrial conduction interruption. No tachycardia could be induced at the end of the procedure and late follow-up was event free.

CONCLUSIONS

The existence of arrhythmogenic atrioatrial conduction should be taken into account when evaluating atrial arrhythmias in the transplanted heart because it is potentially curable by radiofrequency catheter ablation.

Left atrial reduction for chronic atrial fibrillation associated with mitral valve disease

Currently available surgical procedures to control chronic atrial fibrillation associated with mitral valvar disease are not always successful. The size of the left atrium is a major factor in the initiation and maintenance of atrial fibrillation. Here we describe a case of ablation of atrial fibrillation with left atrial reduction and pulmonary vein isolation in a patient with mitral valve disease.

The maze procedure for cure of atrial fibrillation

Atrial fibrillation is the most common dysrhythmia encountered in clinical practice. A significant number of patients fail medical therapy because of inability to convert or control the rhythm pharmacologically, intolerance of the requisite medication, or persistent symptoms despite apparently satisfactory rate control. Based on experimental studies establishing the electrophysiologic basis of atrial fibrillation, a surgical procedure has been developed that is highly effective in restoring sinus rhythm without further requirement for medications. The evolution of this procedure, its current indications, and results are outlined.

When and how to report results of surgery on atrial fibrillation

OBJECTIVE

Several medical, interventional and surgical techniques are used to treat atrial fibrillation, aimed at different goals and having variable success rates. To be able to assess and compare all these techniques a methodology of study and a classification is proposed.

METHODS

We developed a five grade score, named the Santa Crus Score, based upon the post-operative atrial rhythm and the effective atrial contraction. Score 0 corresponds to a persistence of atrial fibrillation, the presence of a regular rhythm is grade 1, 2 or 3 if there is no atrial contraction; right atrial contraction; or bilateral atrial contraction, respectively. Score 4 corresponds to sinus rhythm and bilateral atrial contraction. Surgery for atrial fibrillation was performed on 51 patients since 1992. All patients but two had associated mitrial surgery. Three different maze techniques were performed on 17 patients and the pulmonary veins isolation procedure on 34 patients. Patients were reassessed at 1, 6, 12, 24 and 36 months.

RESULTS

After the maze I procedure atrial fibrillation eradication was achieved in 88% of patients but none scored 4. Three patients changed score during the first year. All maze III patients scored 0 initially and one changed to score 3 in the first year. Sixty percent of the maze IIIA patients scored 4, but one evolved to score 0 at 6 months. The pulmonary veins isolation technique eliminated atrial fibrillation in 71% of the patients initially, and in 60% after 1 year, and achieved a score of 4 in a third of the patients.

CONCLUSION

This classification considers the intermediate grades of success that can occur with absence of atrial fibrillation and is applicable to all forms of therapy.

Operative risks of the maze procedure associated with mitral valve surgery

Twelve patients were operated on for mitral valve disease with concomitant chronic atrial fibrillation. Valve repair was performed in five patients and replacement in seven. Maze I and maze III procedures were applied in eight and four patients, respectively, and are compared. There was a regular rhythm in all maze I patients with a constant junctional rhythm in three and an alternating sinus and junctional rhythm in the remainder. In one case, part of the left atrium was in atrial fibrillation with the remaining atria in sinus rhythm. In the maze III group, one patient was always on a regular rhythm, two had episodes of atrial fibrillation and one was in atrial fibrillation with controlled ventricular rate. Echocardiography showed atrial contraction in two maze I patients, but systolic atrial flow across both atrioventricular valves could only be demonstrated in two patients in the maze III group.

Efficacy of serial electrical cardioversion therapy in patients with chronic atrial fibrillation after valve replacement and implications for surgery to cure atrial fibrillation

Chronic atrial fibrillation (AF) occurs often in the setting of mitral and aortic valve disease. Eventually, these patients undergo valve replacement which improves cardiac function but does not prevent AF. This study investigates which patient may benefit from additional surgery for the cure of AF performed in combination with valve surgery. Seventy-four patients were retrospectively included from our prospective database of patients referred for serial cardioversion therapy between 1986 and 1993. All these patients had chronic AF after valve replacement. After the first electrical cardioversion, patients did not receive antiarrhythmic drugs. Relapses were managed by repeated cardioversions, and then antiarrhythmic drugs were instituted. After a median follow-up of 7 years (range 1.3 to 23), 39 patients had intractable AF. Multivariate analysis revealed that patients with a history of chronic AF before surgery (risk ratio 5.4, confidence intervals 2.5 to 11.3, p = 0.0001) had a poor arrhythmia outcome. In addition, Kaplan-Meier survival analysis demonstrated a lower success rate (p = 0.0017) in patients with mitral valve disease than in those with aortic valve disease. Congestive heart failure (41% vs 6%, p = 0.0007) and cardiovascular mortality (23% vs 9%, p = 0.09) were seen most often in patients with an unsuccessful cardioversion strategy. Thus, patients scheduled for mitral valve surgery with a history of chronic AF should be considered candidates for additional surgery for AF concomitantly performed during valve surgery.

Risks and benefits of combined maze procedure for atrial fibrillation associated with organic heart disease

OBJECTIVES

This study sought to identify the risks and benefits of adding the maze procedure in patients with atrial fibrillation (AF) undergoing operation for underlying organic cardiac disorders.

BACKGROUND

Persistent AF often leaves patients symptomatic even after otherwise successful cardiac surgery.

METHODS

Fifty-one patients undergoing valvular operation and the maze procedure (n = 43) or repair of congenital anomalies (n = 8) combined with the maze procedure were compared with 51 patients (control group) matched for underlying diseases and procedures except for the maze operation. Each group, including 31 patients with a concomitant tricuspid annuloplasty and 12 undergoing reoperation, were similar in age, duration of arrhythmia, degree of cardiomegaly and New York Heart Association functional class.

RESULTS

Patients undergoing the maze procedure had longer cardiopulmonary bypass time (213 vs. 144 min, p < 0.0001), longer cardiac arrest (134 vs. 93 min, p < 0.0001) and greater blood loss with longer respiratory care (39 vs. 18 h p = 0.021) and intensive care unit stay but no mortality. No significant differences were found in catecholamine or transfusion requirements immediately after operation. Sustained AF was much less frequent in the maze group (12% at 1 year) than the control group (86%, p < 0.0001), with an average follow-up period of 32 months (range 25 to 42). Atrial contraction was documented in 41 (80%) and 40 (78%) patients for right and left ventricular filling, respectively, after the maze procedure, resulting in a significantly smaller cardiac size and improved functional capacity. Medication was discontinued in seven patients in the maze group compared with two in the control group.

CONCLUSIONS

Improved restoration of atrial rhythm and contraction with combined maze operation appeared to justify the increased operative time and complexity and postoperative care.