Reentrant and Focal Activations During Atrial Fibrillation in Patients With Atrial Septal Defect

Volume overload impedes the maturation of sarcomeres and T-tubules in the right atria: a potential cause of atrial arrhythmia following delayed atrial septal defect closure

Introduction: Adult patients with atrial septal defects (ASD), the most common form of adult congenital heart disease, often die of arrhythmias, and the immaturity of cardiomyocytes contributes significantly to arrhythmias. ASD typically induces a left-to-right shunt, which then leads to the right atrium (RA) volume overload (VO). Whether or not VO contributes to RA cardiomyocyte immaturity and thereby causes arrhythmias in adult patients with ASD remains unclear. Methods: Here, we developed the first neonatal RA VO mouse model by creating a fistula between the inferior vena cava and abdominal aorta on postnatal day 7. RA VO was confirmed by increases in the mean flow velocity, mean pressure gradient, and velocity time integral across the tricuspid valve, and an increase in the RA diameter and RA area middle section. Results: We found that VO decreased the regularity and length of sarcomeres, and decreased the T-element density, regularity, and index of integrity of T-tubules in RA cardiomyocytes, suggesting that the two most important maturation hallmarks (sarcomere and T-tubules) of RA cardiomyocytes were impaired by VO. Accordingly, the calcium handling capacity of cardiomyocytes from postnatal day 21 (P21) RA was decreased by VO. VO caused a significant elongation of the PR interval. The expression of connexin 43 (Cx43) was decreased in RA VO. Moreover, gene ontology (GO) analysis of the downregulated genes in RA demonstrated that there was an abundance of enriched terms associated with sarcomeres and T-tubules exposed to VO. The results were further verified by qRT-PCR. Conclusions: In conclusion, the first neonatal RA VO mouse model was developed; furthermore, using this neonatal RA VO mouse model, we revealed that VO impeded RA sarcomere and T-tubule maturation, which may be the underlying causes of atrial arrhythmias in adult patients with ASD.

Provocation and localization of atrial ectopy in patients with atrial septal defects

Background

Atrial fibrillation (AF) is associated with atrial septal defects (ASDs), but the mechanism of arrhythmia in these patients is poorly understood. We hypothesised that right-sided atrial ectopy may predominate in this cohort. Here, we aimed to localise the origin of spontaneous and provoked atrial ectopy in ASD patients.

Methods

Following invasive calibration of P-wave axes, 24-h Holter monitoring was used to determine the chamber of origin of spontaneous atrial ectopy. Simultaneous electrogram recording from multiple intra-cardiac catheters was used to determine the chamber of origin of isoprenaline-provoked ectopy. Comparison was made to a group of non-congenital heart disease AF patients.

Results

Amongst ASD patients, a right-sided origin for spontaneous atrial ectopy was significantly more prevalent than a left-sided origin (24/30 patients with right-sided ectopy vs. 14/30 with left-sided ectopy, P = 0.015). Amongst AF patients, there was no difference in the prevalence of spontaneous right vs. left-sided ectopy. For isoprenaline-provoked ectopy, there was no significant difference in the proportions of patients with right-sided or left-sided ectopy in either group.

Conclusions

When spontaneous atrial ectopy occurs in ASD patients, it is significantly more prevalent from a right-sided than left-sided origin. Isoprenaline infusion did not reveal the predilection for right-sided ectopy during electrophysiology study.

Pathophysiology, Risk Factors, and Management of Atrial Fibrillation in Adult Congenital Heart Disease

A confluence of clinical and epidemiologic factors has provoked a steep increase in the prevalence of atrial fibrillation in adults with congenital heart disease. Atrial fibrillation is the most common presenting arrhythmia. Much remains to be unraveled about the mitigating role congenital heart disease, residual hemodynamic defects, surgical ramifications, and shunts and cyanosis on new-onset and recurrent atrial fibrillation in this population. Catheter ablation is increasingly performed for atrial fibrillation. This synopsis provides an overview of current knowledge on atrial fibrillation in adults with congenital heart disease, addresses clinical management, and discusses knowledge gaps and areas for future research.

Efficacy of catheter ablation for patients with atrial fibrillation and atrial septal defect

INTRODUCTION

Given that few studies investigated the efficacy of catheter ablation (CA) in patients with paroxysmal atrial fibrillation (AF) and atrial septal defect (ASD), this study evaluated its effectiveness in patients with paroxysmal AF and ASD.

METHODS AND RESULTS

Of the 216 patients who underwent ASD device closure at two hospitals, 36 patients had paroxysmal AF. After April 2012, CA for AF was performed before ASD device closure (ASD-CA group; n = 20). The ASD-CA group had a significantly higher AF-free survival rate after ASD device closure compared to patients without CA for AF before ASD device closure (ASD-non-CA group; n = 16) (ASD-CA group: 2 patients vs. ASD-non-CA group: 9 patients; follow-up period: 4.2 ± 2.5 years; log-rank p = .01). In addition, the AF-free survival rates were similar between the ASD-CA group and 80 paroxysmal AF patients who underwent CA without any detectable structural heart disease (non-SHD-CA group). The two groups were matched by propensity scores for age, sex, and left atrium dimension (ASD-CA group: 2 patients vs. non-SHD-CA group: 5 patients; follow-up period: 3.3 ± 1.8 years; log-rank p = .28).

CONCLUSION

CA for AF before ASD device closure might be an effective treatment option for patients with paroxysmal AF and ASD.

Percutaneous secundum atrial septal defect closure for the treatment of atrial arrhythmia in the adult: A meta-analysis

BACKGROUND

Atrial arrhythmias are common in patients with atrial septal defects (ASD) but the effects of percutaneous closure on atrial arrhythmia prevalence is unclear. We investigated the effects of ASD device closure and the impact of age at time of closure on prevalent atrial arrythmia.

METHODS

Meta-analysis of studies reporting atrial arrhythmia prevalence in adult patients before and after percutaneous closure was performed. Primary outcomes were prevalence of 'all atrial arrhythmia' and atrial fibrillation alone post closure. Sub-group analysis examined the effects of closure according to age in patients; <40 years, ≥40 and ≥ 60 years. 25 studies were included.

RESULTS

Meta-analysis of all studies demonstrated no reduction in all atrial arrhythmia or atrial fibrillation prevalence post-closure (OR 0.855, 95% CI 0.672 to 1.087, P = .201 and OR 0.818, 95% CI 0.645 to 1.038, P = .099, respectively). A weak reduction in all atrial arrhythmia and atrial fibrillation was seen in patients ≥40 years (OR 0.77, 95% CI 0.616 to 0.979, P = .032 and OR 0.760, 95% CI 0.6 to 0.964, P = .024, respectively) but not ≥60 years (OR 0.822, 95% CI 0.593 to 1.141, P = .242 and OR 0.83, 95% CI 0.598 to 1.152, P = .266, respectively). No data were available in patients <40 years. This, and other limitations, prevents conclusive assessment of the effect of age on arrhythmia prevalence.

CONCLUSIONS

Overall, percutaneous ASD closure is not associated with a reduction in atrial arrhythmia prevalence in this meta-analysis. A weak benefit is seen in patients ≥40 years of age, not present in patients ≥60 years.

Outcomes of Atrial Arrhythmia Surgery in Patients With Congenital Heart Disease: A Systematic Review

Background The improved life expectancy of patients with congenital heart disease is often accompanied by the development of atrial tachyarrhythmias. Similarly, the number of patients requiring redo operations is expected to continue to rise as these patients are aging. Consequently, the role of arrhythmia surgery in the treatment of atrial arrhythmias is likely to become more important in this population. Although atrial arrhythmia surgery is a well-established part of Fontan conversion procedures, evidence-based recommendations for arrhythmia surgery for macroreentrant atrial tachycardia and atrial fibrillation in other patients with congenital heart disease are still lacking. Methods and Results Twenty-eight studies were included in this systematic review. The median reported arrhythmia recurrence was 13% (interquartile range, 4%-26%) during follow-up ranging from 3 months to 15.2 years. A large variation in surgical techniques was observed. Based on the acquired data, biatrial lesions are more effective in the treatment of atrial fibrillation than exclusive right-sided lesions. Right-sided lesions may be more appropriate in the treatment of macroreentrant atrial tachycardia; evidence for the superiority of additional left-sided lesions is lacking. There are not enough data to support the use of exclusive left-sided lesions. Theoretically, prophylactic atrial arrhythmia surgery may be beneficial in this population, but evidence is currently limited. Conclusions To be able to provide recommendations for arrhythmia surgery in patients with congenital heart disease, future studies should report outcomes according to the type of preoperative arrhythmia, underlying congenital heart disease, lesion set, and energy source. This is essential for determining which surgical techniques should ideally be applied under which circumstances.

Surgical treatment for adult congenital heart disease: consideration for indications and procedures

The number of the adult patients with congenital heart diseases (ACHD) continues to grow owing to improvement of surgical results and medical management. Corrective surgery for complex CHD does not always mean complete cure. It is not rare that the patients will visit the cardiology institutes because of secondary lesions due to residua or sequela in adults. Some patients with CHD remain unrepairable with different degree of heart failure and pulmonary arterial hypertension. Association of arrhythmias is common in ACHD patients and sometimes critical. We experienced 265 surgical procedures for ACHD patients at our center between 1999 and 2015. Of these procedures, palliative surgery was performed in 3%, palliation to corrective surgery in 6%, primary repair in 57%, and redo surgery in 34%. Hospital mortality within 30 days in this period was 1.1%. Surgery for ACHD patients is safe, beneficial and low-risk treatment; however, tailored procedures for the individual patient are essential to obtain the optimal quality. A comprehensive multidisciplinary approach is required to fulfill this goal.

Surgical aspects of atrial arrhythmia : Right atrial ablation and anti-arrhythmic surgery in congenital heart disease

BACKGROUND

Atrial arrhythmias are frequently described in congenital heart disease.

OBJECTIVES

To provide a surgical perspective of anti-arrhythmic procedures and strategic approaches.

METHODS

Discussion of the history of anti-arrhythmic treatments in congenital heart disease.

RESULTS

Before the advent of the Maze procedure (first published in 1991), surgery mainly focused on patients with Wolff-Parkinson-White syndrome and also on arrhythmias in Ebstein's malformation. Atrial septal defects (ASD) subsequently received more attention, i.e., in terms of atrial arrhythmia in the natural prognosis and the surgically modified course and in terms of surgical versus transcatheter approaches. Based on the background of various atrial arrhythmia mechanisms of ASD, several surgical procedures have been reported, ranging from the bilateral full Maze procedure to simple modification of right atriotomy. The so-called right atrial Maze procedure occupies a special position from the viewpoint of cardiology in acquired heart disease, especially in cases of frequently occurring right heart failure. In hearts with more complex structural abnormalities, a detailed understanding of the conditions to improve overall surgical outcome and develop future "anti-arrhythmic" strategies is necessary.

CONCLUSIONS

It is important to precisely specify factors in the individual cases, not only morphological diversity but also technical and strategic variations and their consequences. A variety of anti-arrhythmic surgical procedures are currently available. How and when to use which procedure requires professional insight and cautious clinical decision-making.