Irrigated-tip catheter ablation of intraatrial reentrant tachycardia in patients late after surgery of congenital heart disease

Case Report: Remote magnetic navigation and accessory pathways ablation in a single ventricle young adult with complex corrective surgeries

Supraventricular arrhythmias have become an increasingly significant contributor to the risk of mortality and morbidity in adults with complex congenital heart disease (CHD), especially in light of recent advances in palliative corrective surgeries. Because of their unique characteristics, they demand specific treatment approaches. While pharmaco-logical interventions are an option, they have limited effectiveness and may lead to side effects. Although performing radiofrequency ablation (RFA) can be exceptionally challenging in patients with complex CHD, due to particular vascular access and also modified anatomy, it has paved the way to enhance comprehension of the underlying mechanisms of supraventricular arrhythmias. This, in turn, enables the provision of improved therapies and, ultimately, an enhancement in the quality of life and symptom management for these patients. The purpose of this case report is to highlight the benefits of utilizing advanced technologies such as three-dimensional electro-anatomical mapping systems, remote magnetic navigation, and highly flexible mapping and ablation catheters during RFA in a young adult with complex congenital heart disease. Although he lacked venous connections to the right atrium (RA) due to multiple corrective surgeries we, remarkably, were capable to advance a decapolar deflectable diagnostic catheter inside the Fontan tunnel and from there to record and stimulate the RA. Successful ablation of two accessory pathways was achieved with no arrhythmia recurrence during follow-up.

Mapping and Ablation of Atypical Atrial Flutters

Atypical atrial flutters are complex, hard-to-manage atrial arrhythmias. Catheter ablation has progressively emerged as a successful treatment option with a remarkable role played by irrigated-tip catheters and 3D electroanatomic mapping systems. However, despite the improvement of these technologies, the ablation results may be still suboptimal due to the progressive atrial substrate modification occurring in diseased hearts. Hence, a patient-tailored approach is required to improve the long-term success rate in this scenario, aiming at achieving specific procedure end points and detecting any potential arrhythmogenic substrate in each patient.

Atrial Arrhythmia Ablation in Patients With D-Transposition of the Great Arteries and Atrial Switch

BACKGROUND

Patients with D-transposition of the great arteries and atrial switch have a high incidence of atrial arrhythmias. We sought to analyze the arrhythmia substrate, ablation strategies, and outcomes for catheter ablation in this population.

METHODS

An in-depth analysis of all clinical and procedural data in patients with D-transposition of the great arteries, atrial baffles, and atrial arrhythmia ablation was performed.

RESULTS

A cohort of 32 patients (72% male, mean age 38±7 years) underwent ablation for non-AV nodal reentrant tachycardia atrial arrhythmias, and 4 patients underwent AV nodal reentrant tachycardia ablation. Cavotricuspid isthmus flutter (CTI-flutter) was the most common arrhythmia, encountered in 75% of patients, followed by scar-related intraatrial reentrant tachycardia (non-CTI intraatrial reentrant tachycardia, 53%) and focal atrial tachycardia (focal atrial tachycardia, 6%). Among the 32 patients, 26 underwent 31 procedures at our institution. For patients with prior outside intervention, the index ablation at our institution revealed CTI-dependent flutter in 3/5 cases. However, redo ablation after an index ablation with demonstrated bidirectional CTI block revealed different/new arrhythmia substrates (80% non-CTI intraatrial reentrant tachycardia, 40% focal atrial tachycardia). Achieving bidirectional block across the CTI often required ablating on both sides of the baffle (retroaortic access, 81%; using a baffle leak, 11.5%; or transbaffle puncture, 7.7%). Combined approaches were necessary in 19% to reach the critical tissue. Acute procedural success was 81%, and recurrence was documented in 58% of patients. Despite recurrence, clinical arrhythmia burden was significantly reduced post-ablation (P<0.001), with rare episodes, amenable to antiarrhythmic therapy. Redo ablation was required in 5 (19%) patients and uncovered new arrhythmia substrates. AV nodal reentrant tachycardia ablation also required transbaffle approaches in 3/4 patients.

CONCLUSIONS

CTI-dependent flutter was the most common arrhythmia in patients with Dextro-Transposition of the Great Arteries and atrial switch. Transbaffle approaches were often necessary, and, provided that bidirectional CTI block was achieved at the index ablation, late recurrence was due to different arrhythmia mechanisms. Despite recurrence, ablation was associated with significant clinical improvement.

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.

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

[Figure: see text].

New developments in catheter ablation for patients with congenital heart disease

Introduction: There are numerous challenges to catheter ablation in patients with congenital heart disease (CHD), including access to cardiac chambers, distorted anatomies, displaced conduction systems, multiple and/or complex arrhythmia substrates, and excessively thickened walls, or interposed material. Areas covered: Herein, we review recent developments in catheter ablation strategies for patients with CHD that are helpful in addressing these challenges. Expert opinion: Remote magnetic navigation overcomes many challenges associated with vascular obstructions, chamber access, and catheter contact. Patients with CHD may benefit from a range of ablation catheter technologies, including irrigated-tip and contact-force radiofrequency ablation and focal and balloon cryoablation. High-density mapping, along with advances in multipolar catheters and interpolation algorithms, is contributing to new mechanistic insights into complex arrhythmias. Ripple mapping allows the activation wave front to be tracked visually without prior assignment of local activation times or window of interest, and without interpolations of unmapped regions. There is growing interest in measuring conduction velocities to identify arrhythmogenic substrates. Noninvasive mapping with a multielectrode-embedded vest allows prolonged bedside monitoring, which is of particular interest in those with non-sustained or multiple arrhythmias. Further studies are required to assess the role of radiofrequency needle catheters and stereotactic radiotherapy in patients with CHD.

Cryoablation with an 8-mm tip catheter for typical AVNRT in children: a single center 5-year experience

BACKGROUND

In children with typical atrioventricular nodal reentrant tachycardia (tAVNRT), cryoablation is preferred over radiofrequency ablation (RFA) because of its safety profile and acceptable long-term success rates. In this study, we have assessed the utility of 8-mm tip cryocatheters for tAVNRT ablation in our center.

METHODS

All pediatric AVNRT patients who underwent cryoablation with an 8-mm tip cryocatheter in our center between 2013 and 2018 were included. EnSite™ (St. Jude Medical Inc., St. Paul, MN, USA) was used in all patients.

RESULTS

A total of 120 patients (64 females, 53%) were included in this study, and the mean age was 13.9 years with a standard deviation of 2.5 years. Eleven patients (9.1%) had structural heart disease, and 12 patients (10%) had additional arrhythmia substrate. The mean number of effective cryolesions was 8 with a standard deviation of 2.3. Fluoroscopy was used in three patients (2.5%). There were minor complications in only four patients (3.3%)-transient first-degree atrioventricular block or transient incomplete right bundle branch block. Acute success rate of cryoablation was 108/120 (90%). In twelve patients, cryoablation was suboptimal, or it failed. The procedure was completed successfully with RFA in the same session in ten patients. Overall acute success rate of ablation (Cryo ± RFA) was 98.5%. During a mean follow-up period of 24.6 months with a standard deviation of 11.3 months, three patients had recurrence (2.5%). Time between the beginning of the effective cryolesion and termination of AVNRT was found associated with acute success of cryoablation (p = 0.013).

CONCLUSIONS

Cryoablation of AVNRT with an 8-mm tip catheter in children appears to be safe, with an acceptable acute success rate and a low recurrence rate. A faster termination of AVNRT during the cryolesion, slowing down before ending with atrioventricular block, is a good indicator for acute success.

Outcome of ACHD patients with non-inducible versus inducible IART undergoing cavo-tricuspid isthmus ablation: the role of empiric ablation

PURPOSE

Catheter ablation for supraventricular tachycardia (SVT) in adults with congenital heart disease (ACHD) is an important therapeutic option. Cavo-tricuspid isthmus (CTI)-dependent intraatrial re-entrant tachycardia (IART) is common. However, induction of sustained tachycardia at the time of ablation is not always possible. We hypothesised that performing an empiric CTI line in case of non-inducibility leads to good outcomes. Long-term outcomes of empiric versus entrained CTI ablation in ACHD patients were examined.

METHODS

Retrospective, single-centre, case-control study over 7 years. Arrhythmia-free survival after empiric versus entrained CTI ablation was compared.

RESULTS

Eighty-seven CTI ablations were performed in 85 ACHD patients between 2010 and 2017. The mean age of the cohort was 43 years and 48% were male. Underlying aetiology included ASD (31%), VSD (11.4%), AVSD (9.1%), AVR (4.8%), Fallot's (18.4%), Ebstein's (2.3%), Fontan's palliation (9.2%) and atrial switch (13.8%). CTI-dependent IART was entrained in 59 patients whereas it was non-inducible in 28. The latter had an empiric CTI ablation. Forty-three percent of procedures were performed under general anaesthesia. There were no reported procedural complications. There was no significant difference in the mean procedure or fluoroscopy times between the groups (empiric vs entrained CTI; 169.1 vs 183.3 and 28.1 vs 19.9 min). Arrhythmia-free survival was 64.3% versus 72.8% (p value 0.44) in the empiric and entrained groups at 21 months follow-up.

CONCLUSIONS

Long-term outcomes after empiric and entrained CTI ablation for IART in ACHD patients are comparable. This is a safe and effective therapeutic option. In the case of non-inducibility of IART, an empiric CTI line should be considered in this cohort.

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).

Radiofrequency Catheter Ablation of Atrial Tachycardias in Congenital Heart Disease

Background

Radiofrequency catheter ablation has become the treatment strategy of choice for atrial tachyarrhythmias in patients with congenital heart disease (CHD). We analyzed results of radiofrequency catheter ablation in a large cohort of patients with CHD with special reference to complexity of underlying anatomy.

Methods and Results

One hundred and forty-four patients with CHD and atrial tachyarrhythmias undergoing radiofrequency catheter ablation were classified according to complexity of underlying CHD: simple CHD, n=18 (12%); moderate CHD, n=53 (37%); and complex CHD, n=73 (51%). Overall acute success was achieved in 81% of the patients. Acute success was lower for tachycardias involving the left atrium compared with right atrial tachycardias. Complexity of CHD was associated with longer procedure duration. Tachycardia recurrence was observed in 54% of the patients after a total follow-up of 7.4 years. 75% of all recurrences occurred within the first year. Recurrence of tachycardia was more likely in patients with complex surgical atrial anatomy (ie, Fontan palliation or atrial switch procedure). Major complications occurred in 4 patients and were related to vascular access.

Conclusions

Acute procedural success of atrial tachycardia ablation in congenital heart patients was not influenced by complexity of CHD. Long-term outcome with regard to tachycardia recurrence was worse in patients with complex surgical atrial anatomy.

Tachyarrhythmia in patients with congenital heart disease: inevitable destiny?

The prevalence of patients with congenital heart disease (CHD) has increased over the last century. As a result, the number of CHD patients presenting with late, postoperative tachyarrhythmias has increased as well. The aim of this review is to discuss the present knowledge on the mechanisms underlying both atrial and ventricular tachyarrhythmia in patients with CHD and the advantages and disadvantages of the currently available invasive treatment modalities.

[Interventional treatment of tachyarrhythmia in children with congenital heart disease]

In children and adolescents with congenital heart disease (CHD) tachyarrhythmia occurs more frequently compared to patients with otherwise normal hearts. Arrhythmia substrates may be a natural part of certain congenital cardiac malformations or may result from long lasting myocardial deterioration as a result of CHD and/or cardiac surgery. Treatment of tachycardia is more frequently required even in early childhood, as the impact on quality of life, morbidity and mortality is higher due to an often reduced hemodynamic tolerance. Over the past 20 years interventional electrophysiology has been established as the therapy of choice for the majority of chronic or chronically recurrent tachycardia even in children with CHD. The success and risks of treatment are predominantly influenced by the individual expression of the cardiac anomaly and, if surgery has been performed, the highly variant postoperative anatomy. Introduction of 3D electroanatomical mapping systems together with modern cardiac imaging tools have significantly contributed to an improved understanding, particularly in postoperative tachycardia. Despite such progress, success rates are lower and recurrences are more frequent compared to patients without CHD. Complex and often multiple tachycardia courses account for the still limited performance as well as a frequently insufficient lesion formation with the use of radiofrequency current in the hypertrophic and fibrotic myocardium. Electrophysiology in children and adolescents, particularly if CHD is present, represents a highly specialized discipline requiring a high expertise in CHD, CHD surgery and cardiac electrophysiology and is ideally imbedded within an interdisciplinary cardiological and cardiosurgical setting.

Ablation of Arrhythmias in Patients with Adult Congenital Heart Disease

Arrhythmias in adults with congenital heart disease, most commonly related to previous surgical procedures, are a frequent comorbidity in this growing population thanks to the improved outcome of surgical techniques. Re-entrant circuits around areas of scarring and natural barriers, combined with abnormal haemodynamics and the underlying anatomy, are the most common cause for these arrhythmias. They are often poorly tolerated and medical treatment is frequently inadequate. In recent years, catheter ablation has emerged as a successful therapeutic option. New advanced techniques such as the use of modern three-dimensional (3D) navigation systems have contributed to better understanding of the arrhythmia mechanisms and higher success rates of the ablation procedures. In this article we briefly summarise the characteristics of the most common arrhythmias in this patient population and some key aspects in their treatment by catheter ablation.

Efficacy of antiarrhythmic drugs in adults with congenital heart disease and supraventricular tachycardias

Supraventricular tachycardias (SVTs) are a major cause of morbidity in adults with congenital heart disease (CHD). Few data exist on safety and efficacy of antiarrhythmic drugs in this population. Our aim was to determine the efficacy of antiarrhythmic drugs in adults with CHD and first-onset SVT on maintaining sinus rhythm after conversion. This was a multicenter retrospective study including adults with CHD and first-onset SVT from January 2008 to January 2011. First-onset SVT occurred in 92 of 7,171 patients without previous SVT (mean age 51 ± 16 years, 57% women). SVTs included atrial fibrillation and flutter in >80% of the patients. Most of these patients had septal defects (50%) and left-sided lesions (21%). The acute management of SVTs resulted in sinus rhythm in 83 patients, and 89% of these patients were instituted on oral antiarrhythmics to prevent SVT recurrence. After a mean follow-up of 2.5 ± 1.4 years, only 45% of the patients were free from SVT. Class III antiarrhythmics (85% sotalol and 15% amiodarone) were associated with a significantly lesser risk of SVT recurrence compared with all other antiarrhythmic drugs (hazard ratio 0.5, 95% confidence interval 0.27 to 0.96, p = 0.036). However, adverse effects of medication occurred in 22% of the patients, mainly in patients taking amiodarone. In conclusion, in adults with CHD and first-onset SVTs, class III antiarrhythmics are more efficacious in maintaining sinus rhythm after cardioversion than other antiarrhythmics. Sotalol may be considered as the first-choice therapy as this is associated with fewer adverse effects than amiodarone.

Importance of tachycardia cycle length for differentiating typical atrial flutter from scar-related in adult congenital heart disease

BACKGROUND

 Radiofrequency catheter ablation (RFCA) for intraatrial reentrant tachycardia (IART) in congenital heart disease (CHD) remains difficult.

METHODS

 Thirty-four consecutive adult patients (age, 37.6 ± 12.8 years; male, 21) with previously repaired CHD and IART underwent an electrophysiological study and RFCA. CHD included atrial septal defect (ASD, n = 14), tetralogy of Fallot (n = 11), ventricular septal defect (n = 4), pulmonary atresia (n = 2), atrioventricular septal defect (n = 1), transposition of the great arteries (n = 1), and double-outlet right ventricle (n = 1).

RESULTS

 Duration of CHD repair to IART onset was 19.1 ± 8.5 years. Thirty and four patients had single- and double-loop reentrant tachycardia, respectively. Among the total of 38 IARTs, which were mapped, 22 (57.9%) and 13 (34.2%) IARTs were cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) and scar-related AFL, respectively. Typical AFL electrocardiography findings including definite sawtooth appearance in inferior leads and positive F wave in lead V1 were observed in only 12 of 21 patients (57.1%) with CTI-dependent AFL. CTI-dependent AFL had a significantly longer tachycardia cycle length (TCL) than scar-related AFL (267.6 ± 34.4 ms and 235.9 ± 37.0 ms, respectively; P = 0.031). TCL > 250 ms had 79% sensitivity as the cutoff value for differentiating CTI-dependent from scar-related AFL. The acute success rates of RFCA in CTI-dependent and scar-related AFLs were 85.7% and 90.0%, respectively. The recurrence rates in CTI-dependent and scar-related AFLs were 11.1% and 11.1%, respectively, during a follow-up of 21.2 ± 28.3 months.

CONCLUSIONS

 CTI-dependent AFL was the most common IART in adult patients with repaired CHD and was easily manageable by RFCA. TCL might help to differentiate CTI-dependent AFL from other IARTs.

Intra-isthmus reentry associated with uncorrected double inlet left ventricle and transposition of the great arteries

A 62-year-old man with uncorrected cyanotic congenital heart disease involving double inlet left ventricle with visceral and atrial situs solitus, L-looped ventricles, L-transposed great vessels, and pulmonary stenosis, presented with recurrent atrial tachycardia. Entrainment mapping revealed the arrhythmia mechanism to be an uncommon micro-reentrant cavotricuspid isthmus-dependent circuit (intra-isthmus reentry), which was amenable to radiofrequency ablation. This uncommon right atrial arrhythmia is yet to be reported in patients with complex congenital heart disease and was amenable to radiofrequency ablation.

Long-term outcome following ablation of atrial flutter occurring late after atrial septal defect repair

AIMS

In patients with surgical atrial septal defect (ASD) repair, late atrial flutters (AFLs), including cavotricuspid isthmus (CTI)-dependent and non-CTI-dependent scar-related flutter (AFL), are common. Radiofrequency ablation (RFA) of these arrhythmias has a high acute success rate. We aimed to characterize the long-term freedom from atrial arrhythmias in this population.

METHODS

Twenty consecutive patients undergoing RFA for AFL late after ASD repair were included. Electrophysiological assessment included multipolar activation, entrainment, and electroanatomic mapping. Clinical, electrocardiograph, and Holter monitoring follow-up was conducted every 6 months.

RESULTS

Mean age was 53 ± 13 years. Time from surgical repair to RFA was 29 ± 15 years. All patients had CTI-dependent AFL (20/20). There were 1.6 ± 0.7 arrhythmias per patient; other arrhythmias included non-CTI-dependent AFL (14), focal atrial tachycardia (two), and atrioventricular nodal reentry tachycardia (two) . Acute success was obtained in 100%. Five patients with recurrent AFL (three CTI dependent, two non-CTI dependent) at 13 ± 8 months had successful repeat RFA. At 3.2 ± 1.6 years follow-up since the last procedure, 90% of patients with successful RFA for AFL remained free of their clinical arrhythmia. However, 30% of the original 20 patients had documented atrial fibrillation (AF) 2.1 ± 1.6 years after the last procedure; five (25%) required AF intervention. One stroke (5%) occurred in the context of late AF.

CONCLUSION

RFA of AFL occurring late after surgical ASD repair has a low long-term risk of recurrence, although 25% of patients required two procedures. However, there is a high late incidence of AF (30%), with an additional 25% of patients requiring intervention for AF.

Outcome of intra-atrial re-entrant tachycardia catheter ablation in adults with congenital heart disease: negative impact of age and complex atrial surgery

OBJECTIVES

The aim of this study was to determine the acute and long-term outcome of radiofrequency catheter ablation (RFCA) for intra-atrial re-entrant tachycardia (IART) in adults with congenital heart disease (CHD), and predictors of these outcomes.

BACKGROUND

Atrial myopathy can be progressive in CHD and contributes to the substrate for IART. Although the outcome of RFCA for IART has been well described in children and adolescents with CHD, it is unclear whether these results are similar in the adult population.

METHODS

Clinical records of adults with CHD undergoing attempted RFCA of IART were analyzed retrospectively. Multivariate analyses identified clinical and procedural factors that predicted acute and long-term outcomes.

RESULTS

A total of 193 procedures was performed in 130 patients (mean age 40 ± 13 years); 82 of 118 (69%) initially attempted RFCA were successful, defined as termination of all IART circuits. The use of electroanatomic mapping was associated with a successful RFCA, whereas Fontan palliation and Mustard repair were associated with an unsuccessful RFCA. Median clinical follow-up of 77 patients (≥2 months of follow-up) after a successful RFCA was 3.7 years (range 0.2 to 10.2 years). IART recurrence was noted in 48%, cardioversion/reablation in 42%, and death in 4%. Older age and Fontan palliation were independent predictors of IART recurrence.

CONCLUSIONS

In adults with CHD, acute and long-term outcomes of RFCA for IART are similar to those reported for younger cohorts. Complex atrial surgery limits the success of RFCA, and older age is associated with a higher risk of IART recurrence.

Mapping of atrial tachycardia by remote magnetic navigation in postoperative patients with congenital heart disease

OBJECTIVES

The purpose of this study was to investigate if remote magnetic navigation (RMN) offers a reduction of fluoroscopy time when used for atrial tachycardia (AT) mapping in a spectrum of patients with congenital heart disease (CHD) after "simple" or "complex" atrial surgery.

BACKGROUND

Data about AT mapping using RMN in larger populations of patients with CHD are scarce.

METHODS

RMN in combination with electroanatomic mapping was used for AT mapping in 22 patients. According to anatomic complexity, patients were classified into 3 groups: Group 1: patients after minor atrial surgery (n = 7); Group 2: patients after the Fontan operation (n = 9); and group 3: patients after the Senning/Mustard operation (n = 6).

RESULTS

Atrial mapping with a nonirrigated tip RMN catheter was completed successfully in all patients. In Group 1 no significant reduction in fluoroscopy time was noticed over time (mean fluoroscopy time 7.9 minutes). In the 15 patients of group 2 and group 3 with complex CHD, the fluoroscopy time for mapping in the last 9 patients (6.4 +/- 2.8 minutes) was significantly shorter than in the first 6 patients (29.7 +/- 10.5 minutes, P < 0.0001). Acutely successful ablation was achieved in 21 of 22 patients (97%) using the RMN catheter (n = 3) or a conventional catheter (n = 18) without procedural complications.

CONCLUSIONS

RMN for AT mapping in patients with complex atrial anatomy leads to a significant reduction of fluoroscopy time.

Treatment of macro-re-entrant atrial tachycardia based on electroanatomic mapping: identification and ablation of the mid-diastolic isthmus

AIMS

This multicentre prospective study evaluated the ability of electroanatomic mapping (EAM) using a specific parameter setting to identify clearly the mid-diastolically activated isthmus (MDAI) and guide ablation of macro-re-entrant atrial tachycardia (MAT).

METHODS AND RESULTS

Consecutive patients with MAT, different from typical isthmus-dependent atrial flutter, were enrolled. EAM was performed using a specific setting of the window of interest, calculated to identify the MDAI and guide ablation of this area. Sixty-five patients exhibiting 81 MATs (mean cycle length 308 +/- 68 ms) were considered. Thirty-two (49.2%) had previous heart surgery. In 79 of 81 morphologies (97.5%), EAM reconstructed 95.9 +/- 4.3% of the tachycardia circuit and identified the MDAI; 23 of the 79 morphologies (29.1%) were double-loop re-entry. Mapping of two morphologies was incomplete due to MAT termination after catheter bumping. In 73 of 79 mapped morphologies (92.4%), abolition of the MAT was obtained by 13.2 +/- 12.4 applications. During the 14 +/- 4 month follow-up, MAT recurred in 4 of the successfully treated patients (6.8%).

CONCLUSION

EAM using a specific parameter setting proved highly effective at identifying the MDAI in MAT, even in patients with previous surgery and multiple re-entrant loops. Ablation of the MDAI yielded acute arrhythmia suppression with low rate of recurrence during follow-up.

Dual-loop circuits in postoperative atrial macro re-entrant tachycardias

BACKGROUND

Patients may develop dual-loop re-entrant atrial arrhythmias late after open-heart surgery, and mapping and catheter ablation remain challenging despite computer-assisted mapping techniques.

OBJECTIVES

The purpose of the study was to demonstrate the prevalence and characteristics of dual-loop re-entrant arrhythmias, and to define the optimal mapping and ablation strategy.

METHODS

40 consecutive patients (mean (SD) age 52 (12) years) with intra-atrial re-entrant tachycardia (IART) after open-heart surgery (with an incision of the right atrial free wall) were studied. Dual-loop IART was defined as the presence of two simultaneous atrial circuits. After an abrupt tachycardia change during radiofrequency ablation, electrical disconnection of the targeted re-entry isthmus from the remaining circuit was demonstrated by entrainment mapping. Furthermore, the second circuit loop was localised using electroanatomical mapping and/or entrainment mapping.

RESULTS

Dual-loop IART was demonstrated in eight (20%, 5 patients with congenital heart disease, 3 with acquired heart disease) patients. Dual-loop IART included an isthmus-dependant atrial flutter combined with a re-entry related to the atriotomy scar. The diagnosis of dual-loop IART required the comparison of entrainment mapping before and after tachycardia modification. Overall, 35 patients had successful radiofrequency ablation (88%). Success rates were lower in patients with dual-loop IART than in patients without dual-loop IART. Ablation failures in three patients with dual-loop IART were related to the inability to properly transect the second tachycardia isthmus in the right atrial free wall.

CONCLUSIONS

Dual-loop IART is relatively common after heart surgery involving a right atriotomy. Abrupt tachycardia change and specific entrainment mapping manoeuvres demonstrate these circuits. Electroanatomical mapping appears to be important to assist catheter ablation of periatriotomy circuits.