Successful case of complex atrial flutter occurring in a patient with congenitally corrected transposition of the great arteries, aberrant left atrial appendage, and situs inversus
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Congenitally corrected transposition of great arteries (ccTGA) is a rare congenital cardiac defect with atrioventricular and ventriculoarterial discordance which leads to heart failure and limits patients’ lifespan. The extremely aberrant cardiac structure makes electrophysiological procedure and radiofrequency ablation very difficult to be performed in such patients. Until now, there were only sporadical cases that have reported the successful ablation of atrial flutter in ccTGA patients.
We report a case of a 36-year-old male who was diagnosed with dextrocardia, atrial septal defect and congenitally corrected transposition of great arteries (ccTGA) at a young age and received atrial septal defect repair and morphological tricuspid valve plasty in 2014. As for reasons of heart failure and atrial flutter, he frequently suffered from progressively worsening dyspnea and recurrent episodes of palpitations. Cardiac anatomic imaging reconstruction before electrophysiological test revealed an unusually huge left atrial appendage in this patient. After high-density mapping of both right atrium and left atrium, activation mapping showed reentry circuit loops were located in left atrium. Successful ablation strategy was performed under the guidance of high-density mapping and entrainment.
This is a clinical case showing high-density mapping and successful ablation of a complex dual-loop atrial flutter in a patient with ccTGA and aberrant left atrial appendage. The successful procedure corroborates clinical utility of high-density mapping approach in the treatment of the patients with complex congenital heart disease accompanied by rapid arrhythmia, can be simpler, safer and more effective.
KeywordsCongenitally corrected transposition of great arteries Congenital heart disease Atrial flutter High-density mapping Radiofrequency ablation
congenitally corrected transposition of great arteries
congenital heart disease
left atrial appendage
morphological right ventricle
morphologically left ventricular
right superior pulmonary vein
Congenitally corrected transposition of great arteries (ccTGA) is a rare form of congenital heart disease (CHD) with the prevalence being less than 0.5% [1, 2]. Since many other associated anatomical defects, such as atrial septal defect, ventricular septal defect, pulmonary stenosis and abnormalities of the morphological tricuspid valve, occurred in the majority of ccTGA patients, surgical treatment was performed in quite a number of these patients [3, 4]. Enlargement of the heart cavities and surgical scars are the basis for the formation of complex macro-reentrant atrial flutter. Until now, there were only sporadical cases reporting the successful ablation of atrial flutter in ccTGA patients [5, 6].
Here, we report a case of successful ablation in a atrial flutter patient with congenital dextrocardia, ccTGA and aberrant left atrial appendage (LAA), the surgical history of atrial septal defect repair and morphological tricuspid valvuloplasty also make the mechanism of arrhythmia more complicated and confusing. A combination of high-density mapping and classic entrainment mapping is the key to successful ablation of the complex atrial flutter.
Before electrophysiological study (EPS), contrast-enhanced computed tomography was performed to demonstrate the anatomical structure of the abnormal heart. Reconstructed geometric structure of LA revealed an unusually huge LAA (Fig. 1c, d). We also used CARTOSYNC™ to reconstruct the 3-dimensional imaging of atriums and ventricles and conform the spatial relationship between them (Fig. 1e, f), which would be a useful guidance for atrial septal puncture and EPS.
A decapolar steerable electrode catheter was positioned within coronary sinus and a hexapolar electrode catheter was placed in morphologically left ventricular (mLV) separately. The intracardial ECG revealed an atrial flutter with a cycle length (CL) of 257 ms. A PentaRay catheter (Biosense Webster, Inc., Diamond Bar, CA, USA) was used to perform high-density mapping of the RA under the guidance of the Carto 3 system (Biosense Webster, Inc., Diamond Bar, CA, USA). The activation mapping revealed a passive activation pattern from LA to RA, the postpacing interval (PPI) after entrainment at coronary sinus (CS) ostium and free atrial wall were 245 ms and 423 ms, respectively, which means the reentrant circuit comes from LA rather than the RA.
The patient reported no tachycardia episodes during the 8-month follow-up after the procedure. Echocardiogram showed functional left ventricular ejection fraction increased to 49% and functional left ventricular end-diastolic diameter decreased to 60 mm at the 8-month follow-up visit.
Discussion and conclusions
Due to the aberrance of anatomy and the complexity of procedures, only few cases reported radiofrequency ablation therapy for the arrhythmias in ccTGA patients. Our case report reveals several potential experiences in electrophysiological procedure in complex CHD patients: (1) previous reconstruction of the 3-dimensional imaging of atriums before EP test can be a useful guidance for atrial septal puncture and electrophysiological mapping in complex CHD. (2) High-density mapping makes the mechanism of arrhythmia in complex CHD more clear. (3) The combination of high-density mapping and entrainment mapping can simplify the design of ablation strategy.
High-density mapping technology has been developing rapidly in recent years. As for the endocardial mapping in this patient, anatomical and electrogram data from the atrium were automatically collected with rapid, high-density acquisition facilitated by the use of the system in conjunction with the PentaRay catheter. Activation map and voltage map were created with 3156 points in right atrium and 6228 points in left atrium. Previous studies have reported the advantages and effectiveness of high-density mapping in the mapping and ablation of complex arrhythmias [8, 9, 10]. It is essential to comprehensively combine activation map, voltage map and entrainments in the ablation strategy design. In this case, we not only performed the electroanatomic mapping of the atriums, but also used procedure of entrainments to confirm the location of atrial flutter more precisely and reliably. We also found the overlapped area of two reentry circuit loops which maybe the critical isthmus (“red” to “purple” in activation map and confirmed by concealed entrainment). We did not perform first ablation line in this area because of the safety concern about perforation when ablation across the large LAA, and the traditional ablation line from RIPV to morphological tricuspid annulus in this case is also difficult to achieve. Although the first ablation line did not terminate the tachycardia, it did increase the CL of atrial flutter. Entrainments after accomplishment of the first ablation line further verified the overlapped area of two reentry circuit loops still in the critical isthmus. The second ablation line terminated the atrial flutter, which might confirm the mechanism we presented.
We first considered the mechanism of atrial flutter is left atrial dual-loop reentry. The LAA-tricuspid valve isthmus constitutes the common pathway between both reentrant loops, this double-loop reentry. However, another possible explanation is only peri-tricuspid annulus atrial flutter. The first ablation line did not block the circuit but slow down the conduction. The prolonged PPI in anterior wall of TVA might due to rate-dependent decremental conduction across the first ablation line. No matter what mechanism (dual-loop reentry or peri-tricuspid annulus), the bidirectional conduction block across the LAA-tricuspid valve isthmus is key to prevent the long-term recurrence of atrial flutter.
In summary, we describe a complex atrial flutter in a patient with ccTGA and aberrant LAA. The successful procedure outlines the importance of realizing the relationship of atriums pre- and intraprocedural by explicit 3-dimensional reconstruction imaging. In the treatment of the patients with complex CHD accompanied by rapid arrhythmia, the combination of high-density mapping and entrainment mapping can be simpler, safer and more effective.
The authors would like to thank Dr. Win-kuang Shen for his helpful advice and comments. We also thank Hanxu Niu and Xiaomang Wang for their technical support in Carto electrophysiological mapping.
LD is the main operator of this case; FH is the first aid and drafted this article; EL is the second aid; and LZ made a critical revision of article. All the authors read and approved the final manuscript.
Ethics approval and consent to participate
This case report was approved by Institutional Ethics Committee for Biomedical Research of Fuwai Hospital. Proper written informed consent was obtained from this patient.
Consent for publication
Consent for publication has been obtained from this patient.
The authors declare that they have no competing interests.
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