Discussion
Dextrocardia is a rare congenital condition with an incidence of about 1 in 10,0001,the incidence of atrial septal aneurysm is about 2.4%4, and the combination of arrhythmias is even rarer, making catheter ablation more difficult due to its anatomical variants, combined with abnormal pulmonary venous connections or other visceral transposition1,2. This article exhibits a case of a female patient with dextrocardia combined with atrial septal aneurysm and focal atrial tachycardia who underwent successful radiofrequency ablation.
In this case, the patient had focal atrial tachycardia and atrial septal aneurysm, and congenital dextrocardia at the same time, which brought great challenges to our radiofrequency ablation. Fortunately, we successfully and safely completed the radiofrequency ablation procedure and summarized as follows, 1)In patients with dextrocardia undergoing atrial tachycardia, a thorough preoperative evaluation to understand the specific structural variants of the heart is essential, such as cardiac ultrasound and cardiac enhancement CT, which help the operator to perform a thorough preoperative evaluation and formulate an effective ablation strategy, reduce the number of unnecessary punctures and operations, shorten the procedure time and ensure the safety of the procedure. 2)Because the position of the atrium of patients with dextrocardia is opposite to that of ordinary people, the right anterior oblique position and the left anterior oblique position should to be exchanged during fluoroscopy, which is different from the fluoroscopy position of our normal patients. Better assessment of the condition and revision of surgical strategies during surgery. 3) ICE is an advanced application in electrophysiological surgery that can provides real-time imaging modalities with spectral and color Doppler capabilities, integrate directly with electroanatomical mapping systems, can visualize complex anatomical structures, allowing the operator to develop individual ablation strategies, thereby avoiding ineffective ablation and/or reducing the occurrence of surgical complications8. In this case, we administered ICE before performing ablation. On the one hand, confirming that there is no thrombosis in the left atrial appendage, which is the premise of safe operation. On the other hand, a better understanding the special heart structures can guide atrial septal puncture, especially in the presence of an atrial septal aneurysm, and better reaching the designated ablation site. 4) The CARTO 3D imaging system is an important part of the intraoperative procedure, which allows for effective 3D reconstruction of the cardiac structure before ablation, helping the operator to understand the spatial structure of the heart better and improving the safety and effectiveness of intraoperative catheterization. 4)For patients who failed atrial tachycardia radiofrequency ablation in conventional locations, attention should also be paid to non-conventional ablation sites such as the non-coronary sinus during intraoperative electrical activation mapping.
Antiarrhythmic drugs and transcatheter cardiac radiofrequency ablation are the conventional treatment modalities for atrial tachycardia. With the growing experience of transcatheter cardiac radiofrequency ablation, the procedure’s success rate has improved significantly over the past few years. Catheter radiofrequency ablation is routinely performed in experienced centers and, given the side effects of antiarrhythmic drugs, which has become the treatment of choice for atrial tachycardia. However, the anatomical variation of cardiac structure in patients with dextrocardia is still not well known, let alone the presence of atrial septal aneurysm, so the difficulty of successful ablation will undoubtedly be further increased if arrhythmias are concomitant, which has rarely been reported so far.
In 1994, Wu et al10 first reported catheter radiofrequency ablation of a patient with a mirrored dextrocardia and persistent atrioventricular reentrant tachycardia. The procedure was successful and without complications, demonstrating the feasibility of radiofrequency ablation in treating patients with dextrocardia. Vaseghi et al11 reported a patient with mirror-image dextrocardia combined with counter-clockwise atrial flutter in the right atrial, of which the tachycardia was cured by ablation of the tricuspid-inferior vena cava isthmus, the application value of ECG in guiding the ablation of patients with dextrocardia complicated with arrhythmia is also proposed at the same time. Benjamin et al12 proposed in the radiofrequency ablation of patients with dextrocardia complicated with atrial fibrillation and atrial flutter, the use of CARTO for electroanatomical localization of the right atrium, combined with intracardiac echocardiography and fluoroscopy for atrial septal puncture, is helpful for the operator better judge the opposite anatomical position, improving the accuracy and success rate of the operation. Vurgun et al13reported the first case of catheter ablation of scar-associated atrial flutter due to surgical repair of atrial septal defects with dextrocardia and complex venous anomalies. They placed three long sheaths through the femoral vein at the superior vena cava and right atrium to stabilize and control the catheter. Activa­tion mapping with Carto-3D system suggested that the tachycardia spread between the two scars. Tachycardia stops when linear ablation is performed between two scars, demonstrating that radiofrequency ablation with an electroanatomical mapping system is effective and safe in such patients. Zhang et al14reported 19 patients with dextrocardia and arrhythmia who underwent successful transcatheter cardiac radiofrequency ablation, demonstrating that radiofrequency ablation is safe, effective, and feasible in such patients. Combining echocardiography, cardiac computed tomography, and 3D mapping, the application of 3D reconstruction can improve the success rate of catheter ablation. Zhou et al15 reported 10 patients with dextrocardia and arrhythmias undergoing catheter ablation, including atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, intra-atrial reentrant tachycardia, and focal atrial atrial fibrillation. Among them, 9 cases were immediately successful during the operation, and no operative complications occurred. All patients were followed up for 6.3 ± 3.5 years without any arrhythmia recurrence. Proposing that paying attention to the anatomical abnormality of the dextrocardia and the cardiac structure, as well as the adjacent relationship of the surrounding structures, is the key to the success of catheter ablation, and recommending setting the ECG leads in a mirror mode, and invert the fluoroscopic image horizontally, which is conducive to the understanding of intraoperative anatomical positioning. In recent years, in addition to radiofrequency ablation, balloon cryoablation has also been used to treat arrhythmias in patients with dextrocardia. Akkaya et al16 reported the first case of cryoballoon ablation in a patient with focal atrial tachycardia in dextrocardia. The successful ablation of abnormal potentials originating in the superior pulmonary vein inferior to the ramus under the guidance of the Ensite system suggests that cryoballoon ablation may also be safe and feasible in patients with dextrocardia combined with arrhythmias.
In summary, the key to successful catheter ablation in patients with dextrocardia, atrial septal aneurysm, and arrhythmia lies in the preoperative comprehensive analysis of the patient’s examination data to develop a surgical strategy that will lead to faster and better access to the procedure. Necessary preoperative tests include electrocardiogram, echocardiography, and cardiac CTA. During the operation, ICE, fluoroscopic image, and Carto three-dimensional mapping system can be combined to guide catheter positioning better and adjust catheter operation to ensure smooth operation and reduce operation time and complications. Adequate preoperative evaluation, meticulous intraoperative electrophysiological examination and mapping, and the use of the latest assistive technologies are prerequisites for ensuring the safe and effective operation of surgery, and each operator needs to take it seriously.