The Cox-maze IV procedure in its second decade: still the gold standard?

Surgical strategy for atrial fibrillation to prevent stroke in patients undergoing cardiac surgery

OBJECTIVE

The aim of this study was to compare outcomes of the full maze procedure with left atrial appendage closure (LAAc) as concomitant procedures for atrial fibrillation (AF) in patients undergoing cardiovascular surgery.

METHODS

A total of 151 patients (88 men, 62 women) underwent elective AF surgery concomitantly with cardiovascular surgery from April 2005 to December 2019. The mean age at time of operation was 70 years and the mean follow-up period was 5.2 ± 3.8 years. Patients were divided into two groups according to the procedure performed: the maze group (n = 87) and the LAAc group (n = 63).

RESULTS

Patients in the LAAc group were significantly older and had more comorbidities than those in the maze group. The operative mortality rate was significantly higher in the LAAc group. There was no difference in the rate of freedom from cardiac-related death between the groups (p = 0.86). Furthermore, there was no difference in the 5-year rate of freedom from thromboembolic stroke between the maze group and the LAAc group (p  =  0.17). However, the 5-year rate of freedom from heart failure was significantly higher in the maze group compared with the LAAc group (100% vs. 86%  ±  6%, respectively; p  =  0.006).

CONCLUSIONS

Patients undergoing the maze procedure had good operative and long-term results, suggesting that this procedure should be performed if indicated. Concomitant LAAc may be effective for preventing thromboembolic stroke in patients with AF if they have no indication for the maze procedure.

Catheter ablation or surgical therapy in moderate-severe tricuspid regurgitation caused by long-standing persistent atrial fibrillation. Propensity score analysis

BACKGROUND

This study aimed to describe the mid-term outcomes of different treatments in patients with atrial fibrillation caused tricuspid regurgitation.

METHODS

A retrospective study of patients diagnosed as atrial fibrillation caused moderate-severe tricuspid regurgitation undergoing ablation (n = 411) were reviewed. The surgical cohort (n = 114) underwent surgical ablation and tricuspid valve repair; the catheter cohort (n = 279) was selected from those patients who had catheter ablation.

RESULTS

The estimated actuarial 5-year survival rates were 96.8% (95% CI: 92.95-97.78) and 92.0% (95% CI: 85.26-95.78) in the catheter and surgical cohort, respectively. Tethering height was showed as independent risk factors for recurrent atrial fibrillation and tricuspid regurgitation in both cohorts. A matched group analysis using propensity-matched was conducted after categorizing total patients by tethering height < 6 mm and ≥ 6 mm. Kaplan-Meier analysis showed in patients with tethering height < 6 mm, there were no differences in survival from mortality, stroke, recurrent atrial fibrillation and tricuspid regurgitation between two groups. In patients with tethering height ≥ 6 mm, there were significantly higher cumulative incidence of stroke (95% CI, 0.047-0.849; P = 0.029), recurrent atrial fibrillation (95% CI, 0.357-09738; P = 0.039) and tricuspid regurgitation (95% CI, 0.359-0.981; P = 0.042) in catheter group.

CONCLUSIONS

Atrial fibrillation caused tricuspid regurgitation resulted in less leaflets coaptation, which risk the recurrence of atrial fibrillation and tricuspid regurgitation. Patients whose tethering height was less than 6 mm showed satisfying improvement in tricuspid regurgitation with the restoration of sinus rhythm after catheter ablation. However, in patients with severe leaflets tethering, the results favored surgical over catheter.

The Mei mini-maze procedure

Atrial fibrillation is a common clinical arrhythmia with high morbidity and a risk of stroke. The Cox-maze IV procedure that uses radiofrequency energy for ablation is established as an effective way to eliminate atrial fibrillation. Compared to the Cox-maze IV procedure, the video-assisted Wolf mini-maze procedure is associated with reduced surgical trauma, but still requires bilateral thoracotomies, and the ablation line connecting the right and left pulmonary vein isolations cannot be created with a bipolar ablation clamp. We have developed a novel video-assisted mini-maze technique that uses a unilateral (left chest) thoracoscopic approach (the Mei mini-maze procedure).

Bipolar Radiofrequency Ablation on Explanted Human Hearts: How to Ensure Transmural Lesions

BACKGROUND

Bipolar radiofrequency (RF) clamps have been shown to be capable of reproducibly creating transmural lesions with a single ablation in animal models. Unfortunately in clinical experience the bipolar clamps have not been as effective and often require multiple ablations to create conduction block. This study created a new experimental model using fresh, cardioplegically arrested human hearts turned down for transplant to evaluate the performance of a nonirrigated bipolar RF clamp.

METHODS

Nine human hearts turned down for transplant were harvested, and the Cox-Maze IV lesion set was performed with a nonirrigated bipolar RF clamp. In the first 7 hearts a single ablation was performed for each lesion. In the last 2 hearts a set of 2 successive ablations without unclamping were performed. The heart tissue was stained with 2,3,5-triphenyl-tetrazolium chloride. Each ablation lesion was cross-sectioned to assess lesion depth and transmurality.

RESULTS

A single ablation with the bipolar RF clamp resulted in 89% (469/529) of the histologic sections and 65% (42/65) of the lesions being transmural. Of the nontransmural sections, 92% occurred in areas with epicardial fat. Performing 2 successive ablations without unclamping resulted in 100% of the cross-sections (201/201) and lesions (25/25) being transmural.

CONCLUSIONS

A single ablation failed to create a transmural lesion 35% of the time, and this was associated with the presence of epicardial fat. Two successive ablations without unclamping resulted in 100% lesion transmurality using the bipolar RF clamp.

The Role of the Electrophysiologist in Convergent Ablation

Catheter ablation is a well-established treatment for patients with AF in whom sinus rhythm is desired. Both radiofrequency catheter ablation and cryoablation are widely performed, rapidly developing techniques. Convergent ablation is a novel hybrid technique combining an endocardial radiofrequency ablation with a minimally invasive epicardial surgical ablation. Some suggest that hybrid ablation may be more effective than lone endocardial ablation in achieving the elusive goal of maintaining sinus rhythm in patients with non-paroxysmal AF. In this article, the authors examine the safety and efficacy of catheter ablation and convergent ablation for long-standing, persistent AF. We also outline the crucial role that electrophysiologists play, not only as a procedure operator, but also as the coordinator and developer of this multidisciplinary service.

Contemporary Surgical Management of Atrial Fibrillation

Atrial fibrillation is a common arrhythmia which may cause symptoms that significantly impact quality of life and is associated with increased risk of stroke, heart failure, and sudden death. Over the past three decades many surgical techniques as well as catheter-bases procedures have been developed to treat atrial fibrillation. In this review we describe the indications, treatments, outcomes, surgical techniques, and technical advances reported in the literature.

Localization of the sinoatrial and atrioventricular nodal region in neonatal and juvenile ovine hearts

Localization of the components of the cardiac conduction system (CCS) is essential for many therapeutic procedures in cardiac surgery and interventional cardiology. While histological studies provided fundamental insights into CCS localization, this information is incomplete and difficult to translate to aid in intraprocedural localization. To advance our understanding of CCS localization, we set out to establish a framework for quantifying nodal region morphology. Using this framework, we quantitatively analyzed the sinoatrial node (SAN) and atrioventricular node (AVN) in ovine with postmenstrual age ranging from 4.4 to 58.3 months. In particular, we studied the SAN and AVN in relation to the epicardial and endocardial surfaces, respectively. Using anatomical landmarks, we excised the nodes and adjacent tissues, sectioned those at a thickness of 4 μm at 100 μm intervals, and applied Masson's trichrome stain to the sections. These sections were then imaged, segmented to identify nodal tissue, and analyzed to quantify nodal depth and superficial tissue composition. The minimal SAN depth ranged between 20 and 926 μm. AVN minimal depth ranged between 59 and 1192 μm in the AVN extension region, 49 and 980 μm for the compact node, and 148 and 888 μm for the transition to His Bundle region. Using a logarithmic regression model, we found that minimal depth increased logarithmically with age for the AVN (R2 = 0.818, P = 0.002). Also, the myocardial overlay of the AVN was heterogeneous within different regions and decreased with increasing age. Age associated alterations of SAN minimal depth were insignificant. Our study presents examples of characteristic tissue patterns superficial to the AVN and within the SAN. We suggest that the presented framework provides quantitative information for CCS localization. Our studies indicate that procedural methods and localization approaches in regions near the AVN should account for the age of patients in cardiac surgery and interventional cardiology.

Convergent epicardial-endocardial ablation for treatment of long-standing persistent atrial fibrillation: A review of literature

BACKGROUND AND AIM OF STUDY

The convergent procedure (CVP) is a hybrid ablation technique via a subxiphoid incision that has recently emerged as a treatment option for non-paroxysmal atrial fibrillation (npAF). By combining endocardial and epicardial ablation into a simultaneous or staged procedure, the pulmonary vein and posterior left atrium can be isolated with transmural lesion sets while minimizing the risk of proarrhythmic gaps that are a known limitation with endocardial linear lesion sets. We reviewed the 12-month outcomes in patients who underwent CVP compared to those who underwent endocardial catheter ablation (CA) and surgical ablation (SA).

METHODS

A literature search was conducted using the PubMed database for publications related to CVP. Selected studies included detailed 12-month follow-up of patients, patient characteristics, periprocedural complications, use of antiarrhythmic drugs (AADs), and monitoring method.

RESULTS

Five studies with 340 patients who underwent CVP between January 2009 and March 2017 were selected for this review. A total of 8.5% of patients had paroxysmal AF (pAF), 42.2% had persistent AF (peAF), and 49.1% had long-standing persistent AF (lspAF). At 12 months, 81.9% of patients were in sinus rhythm, while 54.1% of patients were in sinus rhythm while not taking AADs. The overall complication rate was 10%.

CONCLUSION

CVP had better 1-year efficacy in eliminating AF when compared to CA. However, SA, specifically the Cox Maze IV, had lower rates of AF recurrence in the npAF patient population. Despite its promising 1-year efficacy rates, the periprocedural complication rate for CVP was significantly higher than both CA and SA.

Surgical treatment of atrial fibrillation: technique of thoracoscopic radiofrequency fragmentation of the left atrium

Presented in the article is a detailed description of a modified technique of minimally invasive surgical treatment of patients with atrial fibrillation - thoracoscopic radiofrequency fragmentation of the left atrium. This modification differs from the prototype GALAXY procedure by a significant increase of the 'quantitative' rather than 'qualitative' parameter of surgical aggression in relation to the left atrium. This technique results in creation of multiple transmural continuous closed lines of lesion to the left atrium and, consequently, a reduced risk of inadequate surgical treatment for atrial fibrillation. Besides the radiofrequency action on the wall of the left atrium, the protocol of the operation included destruction of the ligament of Marshall and resection of the left atrial appendage. An indication for performing this operation is the presence of various forms of atrial fibrillation.

Energy Sources for the Surgical Treatment of Atrial Fibrillation

The surgical treatment of atrial fibrillation has evolved over the past 2 decades due to the advent of ablation technology, and the introduction of less invasive surgical approaches. Current devices produce ablation lines that aim to replace the incisions of traditional surgical ablation strategies, such as the Cox-Maze procedure. This has helped to simplify and shorten surgical ablation procedures and has allowed for the development of minimally invasive surgical techniques. This review discusses surgical ablation energy sources and devices, providing background on device characteristics, mechanism of tissue injury, and success in creating transmural lesions.

Persistent Atrial Fibrillation Ablation: Where Do We Go From Here?

Catheter ablation is being used increasingly for the treatment of atrial fibrillation (AF). Pulmonary vein antral isolation is considered the "cornerstone" for the ablation of AF. This approach has demonstrated consistent rates of success for paroxysmal AF, but the rates of success for persistent AF are lower. There has long been a hypothesis that additional ablation beyond pulmonary vein isolation is required to achieve better outcomes in the population with persistent AF. However, large clinical trials have demonstrated recently that such approaches as empiric linear ablation and/or ablation of complex fractionated electrograms may add no benefit over pulmonary vein isolation alone in persistent AF. Furthermore, new technologies are improving the durability and outcome of pulmonary vein isolation alone. These observations have endorsed a search for new potential targets for adjuvant ablation, which currently include ablation of dynamic phenomena during AF such as rotational and focal activations, ablation of scar regions in the atria, isolation of the left atrial posterior wall, and ablation of nonpulmonary vein triggers. Whether any of these additional approaches will add to the success of ablation for persistent AF is unknown. Smaller study results are mixed. Only the performance of large-scale randomized trials will definitively answer whether additional ablation over pulmonary vein isolation alone with improve outcomes for persistent AF.