Ablation of atrial tachycardia after surgery for congenital and acquired heart disease using an electroanatomic mapping system: Which circuits to expect in which substrate?

Updates in Arrhythmia Management in Adult Congenital Heart Disease

Arrhythmias are highly prevalent in adults with congenital heart disease. For the clinician caring for this population, an understanding of pathophysiology, diagnosis, and management of arrhythmia is essential. Herein we review the latest updates in diagnostics and treatment of tachyarrhythmias and bradyarrhythmias, all in the context of congenital anatomy, hemodynamics, and standard invasive palliations for congenital heart disease.

Mid-term outcomes after catheter ablation in patients with congenital heart disease

INTRODUCTION

Cardiac arrhythmias are a major concern in patients with CHD. The purpose of this study was to evaluate the long-term outcomes in patients with CHD submitted to catheter ablation.

MATERIALS AND METHODS

Observational retrospective study of patients with CHD referred for catheter ablation from January 2016 to December 2021 in a tertiary referral centre. Acute procedural endpoints and long-term outcomes were assessed.

RESULTS

A total of 44 ablation procedures were performed in 36 CHD patients (55% male, mean age 43 ±3 years). Fifty-four arrhythmias were ablated: 23 cavotricuspid isthmus atrial flutters, 10 atrial re-entrant tachycardias, eight focal atrial tachycardias, eight atrial fibrillations, three atrioventricular re-entrant tachycardias, and two ventricular tachycardias. During a median follow-up time of 37 months (interquartile range 12-51), freedom from arrhythmia recurrence was achieved in 93%, with 1.2 procedures per patient (18% with anti-arrhythmic drugs). There were no adverse events related to catheter ablation. No predictors of recurrence were identified.

CONCLUSION

In patients with CHD, catheter ablation presents a high mid-term efficacy while maintaining a safe profile.

Postoperative Cardiac Arrhythmias in Pediatric and Neonatal Patients with Congenital Heart Disease-A Narrative Review

Cardiac arrhythmias are a frequent complication in the evolution of patients with congenital heart disease. Corrective surgery for these malformations is an additional predisposition to the appearance of arrhythmias. Several factors related to the patient, as well as to the therapeutic management, are involved in the etiopathogenesis of cardiac arrhythmias occurring post-operatively. The risk of arrhythmias in the immediate postoperative period is correlated with the patient's young age and low weight at surgery. The change in heart geometry, hemodynamic stress, and post-surgical scars represent the main etiopathogenic factors that can contribute to the occurrence of cardiac arrhythmias in the population of patients with operated-on congenital heart malformations. Clinical manifestations differ depending on the duration of the arrhythmia, underlying structural defects, hemodynamic conditions, and comorbidities. The accurate diagnosis and the establishment of specific management options strongly influence the morbidity and mortality associated with arrhythmias. As such, identifying the risk factors for the occurrence of cardiac arrhythmias in the case of each patient is essential to establish a specific follow-up and management plan to improve the life expectancy and quality of life of children.

Three-Dimensional (3D) Mapping and Catheter Ablation for Simultaneous Reverse Typical and Atypical Atrial Flutter: A Case Report

Atrial flutter, a common cardiac arrhythmia, is characterized by rapid and regular atrial contractions that result in a characteristic sawtooth pattern on the electrocardiogram. It emerges due to the formation of reentrant electrical circuits within the atria, giving rise to structured, sawtooth-patterned atrial waves as observed on electrocardiography. We present the case of a 52-year-old female with a medical history of ankylosing spondylitis, dyslipidemia, and a previous surgical closure of an atrial septal defect. The patient developed a rare form of atrial flutter, characterized by two distinct mechanisms: a clockwise isthmus-dependent flutter and an atypical scar-related flutter around the atriotomy scar. In order to effectively address this complex condition, a successful ablation procedure was performed to target both mechanisms. This case report offers valuable insights into the complexities surrounding the diagnosis and treatment of a complex case characterized by the coexistence of multiple mechanisms of atrial flutter within a single patient. While catheter ablation has demonstrated improved success rates for typical and atypical atrial flutters when occurring in isolation, predicting the prognosis of complex cases continues to pose challenges.

Catheter ablation for supraventricular arrhythmias in adults with congenital heart disease: Recurrence rates and predictors of acute procedural success

Aims

To define the cohort of adult congenital heart disease (ACHD) patients undergoing catheter ablation for supraventricular arrhythmia in a large tertiary centre, characterise outcomes, and determine factors associated with arrhythmia recurrence.

Methods

Single centre retrospective study of all catheter ablations for atrial arrhythmias in ACHD patients between September 2014 and October 2021. Patients were identified using a field search through a centralised database. Pre-specified clinical and procedural data of interest, and time from ablation to recurrence, were determined. Cox regression analyses were used to determine potential predictors of acute procedural success and arrhythmia recurrence.

Results

Cardiac ablation for supraventricular arrhythmia was undertaken in 142 cases across 100 unique patients (median age 41, interquartile range 31-52), with 70 (49%) cases treated for macro-reentrant atrial tachycardia, 16 (11%) for focal atrial tachycardia, 19 (13%) for multifocal atrial tachycardia, 17 (12%) for atrial fibrillation, 7 (5%) for atrioventricular nodal reentrant tachycardia, and 8 (6%) for atrioventricular reentrant tachycardia; and 68 cases (48%) had recurrent arrhythmia with a median time to recurrence of 800 days. Multivariable analysis identified acute procedural success as an independent predictor of freedom from arrhythmia, and ablation for persistent atrial fibrillation as an independent predictor for recurrence of arrhythmia.

Conclusion

Catheter ablation for supraventricular arrhythmia in ACHD patients is safe and effective, with most patients achieving multiple arrhythmia-free months. Procedural success and arrhythmia mechanism are important predictors of recurrence.

Interpretation of Typical and Atypical Atrial Flutters by Precision Electrocardiology Based on Intracardiac Recording

Atrial flutter is a term encompassing multiple clinical entities. Clinical manifestations of these arrhythmias range from typical isthmus-dependent flutter to post-ablation microreentries. Twelve-lead electrocardiogram (ECG) is a diagnostic tool in typical flutter, but it is often unable to clearly localize atrial flutters maintained by more complex reentrant circuits. Electrophysiology study and mapping are able to characterize in fine details all the components of the circuit and determine their electrophysiological properties. Combining these 2 techniques can greatly help in understanding the vectors determining the ECG morphology of the flutter waveforms, increasing the diagnostic usefulness of this tool.

Atrial Flutters in Adults with Congenital Heart Disease

The macroreentrant atrial tachycardia is very frequent in the adults with congenital heart disease. The impact of the arrhythmias on this type of patients is related to several factors: the anatomy and physiopathology of the specific congenital heart disease (CHD), the sequelae of the corrective surgery or surgical palliation, the presence of residual lesions (shunt, regurgitation), and the age and the clinical status of the patient and the comorbidities. In turn, the mechanism of the MAT depends on the peculiar features of the conduction's system in the CHD and native and acquired (post-surgery) substrates.

Procedural Feasibility and Long-Term Efficacy of Catheter Ablation of Atypical Atrial Flutters in a Wide Spectrum of Heart Diseases: An Updated Clinical Overview

Atypical atrial flutters (AAFL) are difficult-to-manage atrial arrhythmias, yet potentially amenable to effective radiofrequency catheter ablation (CA). However, data on CA feasibility are only sparingly reported in the literature in different clinical settings, such as AAFL related to surgical correction of congenital heart disease. The aim of this review was to provide an overview of the clinical settings in which AAFL may occur to help the cardiac electrophysiologist in the prediction of the tachycardia circuit location before CA. Moreover, the role and proper implementation of cutting-edge technologies in this setting were investigated as well as which procedural and clinical factors are associated with long-term failure to maintain sinus rhythm (SR) to find out which patients may, or may not, benefit from this procedure. Not only different surgical and non-surgical scenarios are associated with peculiar anatomical location of AAFL, but we also found that CA of AAFL is generally feasible. The success rate may be as low as 50% in surgically corrected congenital heart disease (CHD) patients but up to about 90% on average after pulmonary vein isolation (PVI) or in patients without structural heart disease. Over the years, the progressive implementation of three-dimensional mapping systems and high-density mapping tools has also proved helpful for ablation of these macro-reentrant circuits. However, the long-term maintenance of SR may still be suboptimal due to the progressive electroanatomic atrial remodeling occurring after cardiac surgery or other interventional procedures, thus limiting the likelihood of successful ablation in specific clinical settings.

Tachyarrhythmias in Congenital Heart Diseases: From Ion Channels to Catheter Ablation

Major advances in pediatric cardiology in recent decades, especially surgical techniques, have resulted in an increasing number of patients with congenital heart disease (CHD) surviving to adulthood. This has generated new challenges, particularly with regards to the late onset of complex arrhythmias. Abnormal anatomy, surgical scarring, chronic hypoxemia, hemodynamic compromise, neuro-hormonal abnormalities, and genetic factors can all contribute to creating a unique substrate for arrhythmia development. This review attempts to synthesize the current state of knowledge spanning the spectrum from underlying mechanisms of arrhythmias in patients with congenital heart disease to current ablative strategies. We discuss existing knowledge gaps and highlight important areas for future research.

Atypical atrial flutter: review of mechanisms, advances in mapping and ablation outcomes

PURPOSE OF REVIEW

Atrial flutter (AFL) is the second most prevalent arrhythmia after atrial fibrillation (AF). It is a macro-reentrant tachycardia that is either cavotricuspid isthmus dependent (typical) or independent (atypical). This review aims at highlighting mechanism, diagnosis and treatment of atypical AFL and the recent developments in electroanatomic mapping.

RECENT FINDINGS

Incidence of left AFL is at an exponential rise presently with increase in AF ablation rates. The mechanism of left AFL is most often peri-mitral, roof-dependent or within pulmonary veins in preablated, in contrast to posterior or anterior wall low voltage areas in ablation naïve patients. Linear lesions, compared to pulmonary vein isolation alone, have higher incidence of atypical right or left AFL. Catheter ablation for atypical AFL is associated with lower rates of thromboembolic events, transfusions, and length of stay compared to typical AFL.

SUMMARY

Advances in mapping have allowed rapid simultaneous acquisition of automatically annotated points in the atria and identification of details of macro-reentrant circuits, including zones of conduction block, scar, and slow conduction.

Contemporary Patients With Congenital Heart Disease: Uniform Atrial Tachycardia Substrates Allow for Clear Ablation Endpoints With Improved Long-Term Outcome

[Figure: see text].

Atrial flutter catheter ablation in adult congenital heart diseases

The important increase in life expectancy of adult patients with congenital heart disease (ACHD) has generated new challenges, including arrhythmias that represent one of the main late complications. Reentrant atrial arrhythmias are by far the main mechanism encountered, and catheter ablation has been now presented as a first-line therapy in this patient population. The number of procedures is expected to continuously increase year after year. The heterogeneity and complexity of phenotypes encountered require these cases to be performed by highly experienced operators, in specialized centers with multidisciplinary competencies. A thorough knowledge and understanding of anatomic specificities, vascular access issues, and main circuits encountered according to underlying phenotype is essential. Acute success rates have significantly improved and are now excellent, but recurrences remain a common issue, with different mechanisms or circuits frequently encountered. Observational data have suggested the interest of systematically targeting all inducible atrial arrhythmias, whether previously documented or not, and a lot of hope and research is based on the prediction of arrhythmia substrate before arrhythmia development by imaging or electroanatomic mapping to deliver a prophylactic patient tailored ablation approach. In this review, we summarize those different points in the most common or distinctive defects to offer a didactic overview of atrial flutter catheter ablation in ACHD patients.

Atrial Fibrillation in Congenital Heart Disease

The increasing prevalence of AF in a growing population of adults with congenital heart disease (CHD) poses new challenges to clinicians involved in the management of these patients. Distinctive underlying anatomies, unique physiological aspects, a high diversity of corrective surgeries and associated comorbidities can complicate clinical decision-making. In this review, the authors provide an overview of the current knowledge on epidemiology and pathophysiology, with a special focus on the differences to the non-CHD population and the clinical impact of AF in adults with CHD. Acute and long-term management strategies are summarised, including the use of antiarrhythmic drugs, catheter or surgical ablation and prophylaxis of thromboembolism. Finally, gaps of knowledge and potential areas of future research are highlighted.

Ablation of atrial tachycardia in the setting of prior mitral valve surgery

BACKGROUND

Data regarding catheter ablation of post-surgical atrial tachycardia occurring after mitral valve surgery are scarce. Through a search of the literature, this study aimed to assess the feasibility of catheter ablation and the characteristics of atrial arrhythmias ablated in these patients.

METHODS

Studies assessing the main procedure parameters and the electrophysiologic findings of the investigated atrial tachycardia were selected. The electrophysiologic mechanism (focal vs. re-entrant arrhythmias), site of arrhythmia origin (left atrium vs. right atrium) and their anatomic correlation with specific surgical access and/or prior Cox-Maze IV procedure were all addressed.

RESULTS

Eleven studies including 206 patients undergoing catheter ablation of 297 post-surgical arrhythmia morphologies occurring after mitral valve surgery were considered. Major complications were observed in 2 patients only (0.9%). Restoration of sinus rhythm was achieved in 96% of patients. Macro-reentrant arrhythmia was mostly observed (90.4%) with a non-negligible proportion of focal arrhythmia (9.6%). Left-sided arrhythmia was common (54.4%,) but cavotricuspid isthmus-dependent arrhythmia was frequently reported (33%). Although specific atriotomies showed trends towards peculiar locations of the investigated arrhythmia, Cox-Maze IV procedure was the only independent predictor for left-sided arrhythmia (OR=17.3; 95% CI 7.2-41.2; P<0.0001).

CONCLUSIONS

Catheter ablation of post-surgical arrhythmia occurring after mitral valve surgery is feasible, and, in this setting, the vast majority of the arrhythmia morphologies are based on macro-reentry and in about one third of cases show cavotricuspid isthmus-dependent arrhythmia. Prior Cox-Maze-IV associated with mitral valve surgery is an independent predictor of left-sided arrhythmia possibly due to non-transmural surgical lesions.

Extensive scar modification for the treatment of intra-atrial re-entrant tachycardia in patients after congenital heart surgery

BACKGROUND

Catheter ablation is an important therapeutic option for atrial tachycardias in patients with CHD. As a result of extensive scarring and surgical repair, multiple intra-atrial re-entrant tachycardia circuits develop and serve as a substrate for arrhythmias. The best ablation approach for patients with multiple intra-atrial re-entrant tachycardias has not been investigated. Here, we compared substrate-based ablation using extensive scar modification to conventional ablation.

METHODS

The present study included patients with surgically corrected CHD that underwent intra-atrial re-entrant tachycardia ablation. Extensive scar modification was defined as substrate ablation based on a dense voltage map, aimed to eliminate all potentials in the scar region. The control group had activation mapping-based ablation. A clinical composite endpoint was assessed. Points were given for type, number, and treatment of intra-atrial re-entrant tachycardia recurrence.

RESULTS

In 40 patients, 63 (extensive scar modification 13) procedures were performed. Acute procedural success was achieved in 78%. Procedural duration was similar in both groups. Forty-nine percent had a recurrence within 1 year. During a 5-year follow-up (2.5-7.5 years), 46% required repeat catheter ablation. Compared to baseline, clinical composite endpoint significantly decreased by 46% after 12 months (p = 0.001). Acute procedural success, procedural parameters, recurrence and repeat ablation were similar between extensive scar modification and activation mapping-based ablation.

CONCLUSION

Catheter ablation using extensive scar modification for intra-atrial re-entrant tachycardias occurring after surgically corrected CHD illustrated similar short- and long-term outcomes and procedural efficiency compared to catheter ablation using activation mapping-based ablation. The choice of ablation approach for multiple intra-atrial re-entrant tachycardia should remain at the discretion of the operator.

High-density mapping of multiple atypical atrial flutter. First HD GRID mapping experience among The Commonwealth of Independent States

Mapping of multiple atrial tachycardias after previous cryoballoon pulmonary vein isolations and multiple radiofrequency ablations can be challenging even for experienced specialists. HD Grid high-density mapping catheter is one of the catheters, which helps not only to precisely identify the mechanisms of macro-reentry tachycardia but also to avoid unnecessary radiofrequency applications. Accordingly, we present two cases of complex atrial arrhythmia with the use of HD Grid, which showed clear visualization of mechanisms and target ablations with the termination of tachycardia.

Multi-electrode mapping of complex macroreentry atrial tachycardia

BACKGROUND

Multi-electrode mapping (MEM) is increasingly applied in ablation of complex atrial arrhythmias. This study aimed to evaluate MEM for analysis and treatment of complex macroreentry atrial tachycardia (MAT).

METHODS

Patients with MAT related to scarring, history of heart surgery or atrial linear ablation were studied. Patients were mapped with conventional activation mapping (CAM) or MEM. After characterizing the mechanism of atrial tachycardia (AT), the ablation was performed.

RESULTS

The study consisted of 114 eligible patients, 74 in the CAM and 40 in MEM. Compared with CAM, MEM had a shorter procedure duration (156.7 ± 59.1 ms vs. 127.3 ± 59.3 ms, P = 0.003) and mapping duration (62.6 ± 35.7 ms vs. 30.5 ± 15.3 ms, P < 0.001) and more mapping points (1364.9 ± 828.7 points vs. 148.3 ± 79.6 points, P < 0.001). There were no significant differences between CAM and MEM in acute ablation success rate, complication, postoperative AADs, and ablation duration. The mean disease-free survival time in CAM versus MEM was 20.8 (95% CI: 17.6-24.1) months versus 26.6 (95% CI: 22.7-30.4) months. The median disease-free survival time in the CAM versus MEM was 20.0 (95% CI: 13.9-26.1) months versus 30.0 (95% CI: 26.7-36.3) months. The AT recurrence risk of MEM was 0.522 times that of CAM (HR 95% CI: 0.282-0.968; P = 0.039).

CONCLUSION

MEM is strongly recommended in ablation of complex MAT.

Mechanisms of Intra-Atrial Re-Entrant Tachycardias in Congenital Heart Disease: Types and Predictors

Intra-atrial re-entrant tachycardia (IART) is a severe complication in patients with congenital heart disease (CHD). Cavotricuspid isthmus (CTI)-related IART is the most frequent mechanism. However, due to fibrosis and surgical scars, non-CTI-related IART is frequent. The main objective of this study was to describe the types of IART, circuit locations, and to analyze predictors of CTI versus non-CTI-related IART. This is an observational study that includes all consecutive patients with CHD who underwent a first IART ablation in a single referral tertiary hospital from January 2009 to December 2015 (94 patients; 39.4% women; age: 36.55 ± 14.9 years, 40.4% with highly complex cardiac disease). During the study, 114 IARTs were ablated (1.21 ± 0.41 IARTs per patient). CTI-related IART was the only arrhythmia in 51% (n = 48) of patients; non-CTI-related IART was the only mechanism in 27.7% (n = 26), and 21.3% of patients (n = 20) presented the two types of IART. Severe dilation of the systemic ventricle, absence of severe dilation of the venous atrium, highly complex cardiac defects, and nontypical electrocardiography (ECG) were related to non-CTI-related IART in univariate analysis. In multivariate analysis, nontypical ECG (odds ratio 3.64; 1.01 to 4.9; p = 0.049) and grade III CHD complexity (odds ratio 9.43; 1.44 to 11.7; p = 0.001) were predictors of non-CTI-related IART. In conclusion, in our population with a high proportion of complex CHD, CTI-related IART was the most frequent mechanism, although non-CTI-related IART was present in 49% (alone or with concomitant CTI-related IART). High-grade CHD complexity and nontypical ECG were strongly related to non-CTI IART.

Right atrial dual-loop reentrant tachycardia after cardiac surgery: Prevalence, electrophysiological characteristics, and ablation outcomes

BACKGROUND

Right atrial (RA) dual-loop reentrant tachycardia has been described in patients who have undergone open heart surgery. However, the prevalence, electrophysiological (EP) substrate, and ablation outcomes have been poorly characterized.

OBJECTIVE

The purpose of this study was to investigate the prevalence, EP substrate, and ablation outcomes for RA dual-loop reentrant tachycardia after cardiac surgery.

METHODS

We identified all patients with atrial tachycardia (AT) after cardiac surgery. We compared EP findings and outcomes of those with RA dual-loop reentrant tachycardia to a control group of patients with RA macroreentrant arrhythmias in the setting of linear RA free-wall (FW) scar.

RESULTS

Of the 127 patients with 152 postsurgical ATs, 28 of the ATs (18.4%) had RA dual-loop reentry and 24 of 28 (85.7%) had tricuspid annular reentry combined with FW incisional reentry. An incision length >51.5 mm along the FW predicted the substrate for a second loop. In 22 of 23 patients (95.7%) with initial ablation in the cavotricuspid isthmus, a change in the interval between Halo_d to CS_p could be recorded, and 15 of 23 patients (65.2%) had coronary sinus activation pattern change. Complete success was achieved in 25 of 28 patients (89.3%) in the dual-loop reentry group and in 64 of 69 patients (92.8%) in the control group. After mean follow-up of 33.9 ± 24.2 months, 24 of 28 patients (85.7%) and 60 of 69 patients (86.95%) were free of arrhythmias after the initial procedure in the 2 groups, respectively.

CONCLUSION

The prevalence of RA dual-loop reentry is 18.4% of ATs with prior atriotomy scar. A long incision should alert physicians to the possibility of a second loop at the FW. Halo and coronary sinus activation patterns provide important clues to circuit transformation.

Predictors of Acute Failure Ablation of Intra-atrial Re-entrant Tachycardia in Patients With Congenital Heart Disease: Cardiac Disease, Atypical Flutter, and Previous Atrial Fibrillation

BACKGROUND

Intra-atrial re-entrant tachycardia (IART) in patients with congenital heart disease (CHD) increases morbidity and mortality. Radiofrequency catheter ablation has evolved as the first-line treatment. The aim of this study was to analyze the acute success and to identify predictors of failed IART radiofrequency catheter ablation in CHD.

METHODS AND RESULTS

The observational study included all consecutive patients with CHD who underwent a first ablation procedure for IART at a single center from January 2009 to December 2015 (94 patients, 39.4% female, age: 36.55±14.9 years). In the first procedure, 114 IART were ablated (acute success: 74.6%; 1.21±0.41 IART per patient) with an acute success of 74.5%. Cavotricuspid isthmus-related IART was the only arrhythmia in 51%; non-cavotricuspid isthmus-related IART was the only mechanism in 27.7% and 21.3% of the patients had both types of IART. Predictors of acute radiofrequency catheter ablation failure were as follows: nonrelated cavotricuspid isthmus IART (odds ratio 7.3; confidence interval [CI], 1.9-17.9; P=0.04), previous atrial fibrillation (odds ratio 6.1; CI, 1.3-18.4; P=0.02), transposition of great arteries (odds ratio, 4.9; CI, 1.4-17.2; P=0.01) and systemic ventricle dilation (odds ratio 4.8; CI, 1.1-21.7; P=0.04) with an area under the receiver operating characteristic curve of 0.83±0.056 (CI, 0.74-0.93, P=0.001). After a mean follow-up longer than 3.5 years, 78.3% of the patients were in sinus rhythm (33.1% of the patients required more than 1 radiofrequency catheter ablation procedure).

CONCLUSIONS

Although ablation in CHD is a challenging procedure, acute success of 75% can be achieved in moderate-highly complex CHD patients in a referral center. Predictors of failed ablation are IART different from cavotricuspid isthmus, previous atrial fibrillation, and markers of complex CHD (transposition of great arteries, systemic ventricle dilation).

Rhythm disturbances and treatment strategies in children with congenitally corrected transposition of the great arteries

BACKGROUND

We aimed to evaluate rhythm abnormalities in cases of congenitally corrected transposition of the great arteries (ccTGA) and associated treatment strategies.

PATIENTS AND METHODS

This retrospective cohort study included 65 pediatric patients with ccTGA who were admitted to the clinic between 2009 and 2017. The patients were divided into two groups, and surgical data, Holter electrocardiographic (ECG) recordings, ECG recordings, electrophysiological data, and device implantation data on the two groups were compared.

RESULTS

Group I (n = 53, 82%) consisted of patients with significant associated lesions, and Group II (n = 12, 18%) consisted of those with minor or no associated lesions (isolated ccTGA). Rhythm abnormalities were diagnosed in 22 (34%) of the patients based on initial ECG findings and Holter ECG recordings. Eleven (17%) of these patients had atrioventricular (AV) block of different degrees, and the other 11 (17%) had supraventricular arrhythmia (SVA). The median follow-up was 49 months (range, 9-89 months), and the rhythm remained normal in 26 (42%) of the patients. Three patients died on follow-up. Of 40 patients with normal initial findings, nine required pacemaker implantation due to complete heart block, and SVA developed in seven patients on follow-up. No ventricular tachycardia was seen initially or on follow-up. Ablation was performed in four patients. During the follow-up period, pacemakers were implanted in 12 (23%) of patients in Group I and 4 (33%) of patients in Group II due to complete heart block. Cardiac resynchronization therapy (CRT) was performed in four patients due to systemic ventricular dysfunction. Notably, all four of these patients had a pacemaker implanted postoperatively.

Focal Atrial Tachycardia Arising from the Inferior Vena Cava

The inferior vena cava (IVC) is a rare site of focal atrial tachycardia (AT). Here, we report a 20-year-old woman who underwent catheter ablation for anti-arrhythmic drug-resistant AT originating from the IVC. She had undergone open-heart surgery for patch closure of an atrial septal defect 17 years previously and permanent pacemaker implantation for sinus node dysfunction 6 years previously. The AT focus was at the anterolateral aspect of the IVC-right atrial junction, and it was successfully ablated under three-dimensional electroanatomical-mapping guidance. We suspect that the mechanism of this tachycardia was associated with previous IVC cannulation for open-heart surgery.

Arrhythmia Surgery for Adults with Congenital Heart Disease

Patients with repaired or unrepaired congenital heart anomalies are at increased risk for arrhythmia development throughout their lives, often paralleling the need for reoperations for hemodynamic residua. The ability to incorporate arrhythmia surgery into reoperations can result in improvement in functional class and decreased need for antiarrhythmic medications. Every reoperation for congenital heart disease can be viewed as an opportunity to assess the electrical and arrhythmia substrates and to intervene to improve the arrhythmias and the hemodynamic condition of the patient. The authors review and summarize the operative techniques for arrhythmia surgery that are based on the arrhythmia mechanisms.

Supraventricular Arrhythmias in Patients with Adult Congenital Heart Disease

An increasing number of patients with congenital heart disease survive to adulthood; such prolonged survival is related to a rapid evolution of successful surgical repairs and modern diagnostic techniques. Despite these improvements, corrective atrial incisions performed at surgery still lead to subsequent myocardial scarring harbouring a potential substrate for macro-reentrant atrial tachycardia. Macroreentrant atrial tachycardias are the most common (75 %) type of supraventricular tachycardia (SVT) in patients with adult congenital heart disease (ACHD). Patients with ACHD, atrial tachycardias and impaired ventricular function - important risk factors for sudden cardiac death (SCD) - have a 2-9 % SCD risk per decade. Moreover, ACHD imposes certain considerations when choosing antiarrhythmic drugs from a safety aspect and also when considering catheter ablation procedures related to the inherent cardiac anatomical barriers and required expertise. Expert recommendations for physicians managing these patients are therefore mandatory. This review summarises current evidence-based developments in the field, focusing on advances in and general recommendations for the management of ACHD, including the recently published recommendations on management of SVT by the European Heart Rhythm Association.

Arrhythmias Following the Mustard and Senning Operations for Dextro-Transposition of the Great Arteries: Clinical Aspects and Catheter Ablation

The atrial switch operations, the Mustard and Senning procedures, performed for dextro-transposition of the great arteries, have largely been supplanted by the arterial switch operation. As such, affected patients will only exist for approximately 30 more years. The main arrhythmias in these patients include sinoatrial node dysfunction, intraatrial reentry tachycardia, and sudden death. Device therapy for these patients is well-established, and catheter ablation for atrial tachycardias is highly efficacious. The application of meticulous procedural planning, customization of catheter courses, and electrophysiologic principles to this patient group may be extended to all postoperative complex congenital heart patients.

Atrial Flutter, Typical and Atypical: A Review

Clinical electrophysiology has made the traditional classification of rapid atrial rhythms into flutter and tachycardia of little clinical use. Electrophysiological studies have defined multiple mechanisms of tachycardia, both re-entrant and focal, with varying ECG morphologies and rates, authenticated by the results of catheter ablation of the focal triggers or critical isthmuses of re-entry circuits. In patients without a history of heart disease, cardiac surgery or catheter ablation, typical flutter ECG remains predictive of a right atrial re-entry circuit dependent on the inferior vena cava-tricuspid isthmus that can be very effectively treated by ablation, although late incidence of atrial fibrillation remains a problem. Secondary prevention, based on the treatment of associated atrial fibrillation risk factors, is emerging as a therapeutic option. In patients subjected to cardiac surgery or catheter ablation for the treatment of atrial fibrillation or showing atypical ECG patterns, macro-re-entrant and focal tachycardia mechanisms can be very complex and electrophysiological studies are necessary to guide ablation treatment in poorly tolerated cases.

Anatomical Substrates and Ablation of Reentrant Atrial and Ventricular Tachycardias in Repaired Congenital Heart Disease

Advances in surgical repair techniques for various types of congenital heart disease have improved survival into adulthood over the past decades, thus exposing these patients to a high risk of atrial and ventricular arrhythmias later in life. These arrhythmias arise from complex arrhythmogenic substrates. Substrate formation may depend on both pathological myocardial remodelling and variable anatomical boundaries, determined by the type and timing of prior corrective surgery. Accordingly, arrhythmogenic substrates after repair have changed as a result of evolving surgical techniques. Radiofrequency catheter ablation offers an important therapeutic option but remains challenging due to the variable anatomy, surgically created obstacles and the complex arrhythmogenic substrates. Recent technical developments including electroanatomical mapping and image integration for delineating the anatomy facilitate complex catheter ablation procedures. The purpose of this review is to provide an update on the changing anatomical arrhythmogenic substrates and their potential impact on catheter ablation in patients with repaired congenital heart disease and tachyarrhythmias.

Prophylactic arrhythmia surgery in association with congenital heart disease

Certain congenital heart anomalies make patients more susceptible to arrhythmia development throughout their lives. This poses the question whether prophylactic arrhythmia surgery should be incorporated into reparative open heart procedures for congenital heart disease. There is currently no consensus on what constitutes a standard prophylactic procedure, owing to the questions that remain regarding lesions to be performed; energy sources to use; proximity of energy source or incisions to coronary arteries, sinoatrial node, atrioventricular node; circumstances for right atrial, left atrial, or biatrial appendectomy; and whether to perform a right, left, or biatrial maze procedure. These considerations are important because prophylactic arrhythmia procedures are performed without knowing if the patient will actually develop an arrhythmia in his or her lifetime. By reviewing and summarizing the literature, congenital heart disease patients who are at risk for developing atrial arrhythmias can be identified and lesion sets can be suggested in an effort to standardize experimental protocols for prophylactic arrhythmia surgery.

Maximizing the Effectiveness of Ablation for Arrhythmias in the Congenital Heart Patients

Arrhythmias are common in adults with congenital heart disease and account for a large proportion of hospitalizations. The complex anatomical heterogeneity, often in the presence of a delicate hemodynamic system, presents a significant electrophysiological challenge. This review outlines current clinical practice and advances in maximizing the effectiveness of ablation for arrhythmias in congenital heart patients.

Executive Summary: European Heart Rhythm Association Consensus Document on the Management of Supraventricular Arrhythmias: Endorsed by Heart Rhythm Society (HRS), Asia-Pacific Heart Rhythm Society (APHRS), and Sociedad Latinoamericana de Estimulación Cardiaca y Electrofisiologia (SOLAECE)

This paper is an executive summary of the full European Heart Rhythm Association (EHRA) consensus document on the management of supraventricular arrhythmias, published in Europace. It summarises developments in the field and provides recommendations for patient management, with particular emphasis on new advances since the previous European Society of Cardiology guidelines. The EHRA consensus document is available to read in full at http://europace.oxfordjournals.org.

Very long-term outcome of catheter ablation of post-incisional atrial tachycardia: Role of incisional and non-incisional scar

BACKGROUND

The arrhythmogenicity of right atrial (RA) incisional scar after cardiac surgery could result in atrial tachycardia (AT). Radiofrequency catheter ablation is effective in the treatment of such tachycardia. However, data regarding long-term outcomes are limited.

METHODS AND RESULTS

A total of 105 patients with prior RA incision who underwent radiofrequency catheter ablation of AT were included. In the first procedure, electroanatomic mapping (EAM) revealed a total of 139 ATs in 105 patients, including 88 cavotricuspid isthmus dependent atrial flutters (IDAFs), 5 mitral annulus reentrant tachycardias (MARTs), 44 intra-atrial reentrant tachycardias (IARTs) and 2 focal ATs (FATs). AT was successfully eliminated in 101 (96.1%) patients. During a mean follow-up period of 90 ± 36 months, recurrent AT was observed in 23 patients and 21 underwent a second ablation. A total of 23 ATs were identified in redo procedures including 4 IDAFs, 2 MARTs, 12 IARTs and 5 FATs. The time to recurrence was significantly different among various AT types. Acute success was achieved in 20 of 23 redo procedures. Taking a total of 21 patients presenting atrial fibrillation during follow-up into account, 85 patients (81.9%) were in sinus rhythm. No complications except for a case of RA compartmentation occurred.

CONCLUSION

RA incisional scar played an essential role in promoting both IDAF and IART, while non-incisional scar contributed to a substantial rate of late recurrent AT in forms of both macroreentry and small reentry. Catheter ablation using EAM system resulted in a high success rate during long-term follow-up.

Impact of previous cardiac surgery on long-term outcome of cavotricuspid isthmus-dependent atrial flutter ablation

AIMS

The aim of this study was to determine the acute and long-term outcome of radiofrequency catheter ablation (RFCA) for cavotricuspid isthmus-dependent atrial flutter (CTI-AFL) in adults with and without previous cardiac surgery (PCS), and predictors of these outcomes. Structural alterations of the anatomical substrate of the CTI-AFL are observed in post-operative patients, and these may have an impact on the acute success of the ablation and in the long-term.

METHODS AND RESULTS

Clinical records of consecutive adults undergoing RFCA of CTI-AFL were analysed. Two main groups were considered: No PCS and PCS patients, who were further subdivided into acquired heart disease (AHD: ischaemic heart disease and valvular/mixed heart disease) and congenital heart disease [CHD: ostium secundum atrial septal defect (OS-ASD) and complex CHD]. Multivariate analysis identified clinical and procedural factors that predicted acute and long-term outcomes. A total of 666 patients (73% men, age 65 ± 12 years) were included: 307 of them with PCS. Ablation was successful in 647 patients (97%), 96% in the PCS group and 98% in the No PCS group (P = 0.13). Regression analysis showed that surgically corrected complex CHD was related to failure of the procedure [odds ratio 5.6; 95% confidence interval (CI) 1.6-18, P = 0.008]. After a follow-up of 45 ± 15 months, recurrences were observed in 90 patients (14%), more frequently in the PCS group: absolute risk of recurrence 18 vs. 10.5%, relative risk 1.71, 95% CI: 1.2-2.5, P = 0.006. Multivariate analysis indicated that the types of PCS [OS-ASD vs. No PCS: hazard ratio (HR) 2.57; 95% CI: 1.1-6.2, P = 0.03 and complex CHD vs. No PCS: HR 2.75; 95% CI: 1.41-5.48, P = 0.004], female gender (HR 1.55; 95% CI: 1.04-2.4, P = 0.048), and severe LV dysfunction (HR 1.36; 95% CI: 1.06-1.67, P = 0.04) were independent predictors of long-term recurrence.

CONCLUSION

Radiofrequency catheter ablation of CTI-AFL after surgical correction of AHD and CHD is associated with high acute success rates. The severity of the structural alterations of the underlying heart disease and consequently the type of surgical correction correlates with higher risk for recurrence.