doi: 10.1161/CIRCEP.108.783423
Images and Case Reports in Arrhythmia and Electrophysiology |
Ablation of Atrial Tachycardia From a Giant Left Superior Vena Cava Using Integration With Computed Tomographic Imaging
From the Cardiology Unit, Cardiovascular Department (P.D.F., R.B., A.B., F.C.), Ospedali Riuniti di Bergamo, Bergamo and Biosense Webster (S.C.), Milan, Italy.
Correspondence to Francesco Cantù, MD, Cardiology Unit, Cardiovascular Department, Ospedali Riuniti di Bergamo, Largo Barozzi 1, 24128 Bergamo, Italy. E-mail fcantu{at}ospedaliriuniti.bergamo.it
A 49-year-old woman affected by the Turner syndrome with a history of repaired congenital cardiomyopathy and persistent atrial tachycardia was referred to our center for radiofrequency ablation. At 11 years of age, she had undergone a surgical closure of an ostium secundum atrial septal defect (direct suture) combined with ligation of a persistent left superior vena cava, the embryological precursor of the ligament of Marshall, at the level of its connection to the coronary sinus. At hospitalization, her electrocardiogram showed an atrial tachycardia (cycle length 375 ms) with long phases of 1:1 atrioventricular conduction. Before the procedure, a computed tomography (CT) scan was performed to merge the anatomic data with the electrophysiological findings during the procedure (CARTO-MERGE, Biosense Webster, Inc, Diamond Bar, Calif). The preacquired CT image, processed with CARTO-MERGE system, showed the presence of a giant left superior vena cava (isolated from the coronary sinus) and a sinus venosus defect (SVD) associated with a right-sided anomalous pulmonary venous connection. In detail, both right superior pulmonary vein and right inferior pulmonary vein drained into the superior caval atrial junction. Van Praagh et al1 reported that SVD appears to be a deficiency in the wall that normally separates the right pulmonary veins from the right sinus venosus. This deficiency unroofs the pulmonary vein, permitting it to drain into the right side of the heart (Figure 1).
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The SVD was not identified at the time of surgery when an ostium secundum atrial septum defect was closed anteriorly to the muscular border of the fossa ovalis.
Integration of the 3D segmented CT images into the real-time electroanatomic mapping was performed by the registration process of the corresponding anatomic points acquired in the right atrium and left atrium (LA). The superimposition of the segmented 3D images allowed the real-time navigation of the mapping and ablation catheter in the complex anatomy of this patient. A 10-pole catheter was placed in the coronary sinus, and a Thermocool irrigated-tip catheter was used for mapping and ablation (NAVISTAR Thermocool, Biosense Webster, Inc, Diamond Bar, Calif). During tachycardia, an electroanatomic activation map of right atrium and coronary sinus combined with entrainment maneuvers showed a bystander activation of those chambers. Passing through the SVD, a map of the LA was performed with evidence of a focal origin coming from the wall of the LA in contact with the giant left superior vena cava. Repeated ablation at the earliest site in the LA slowed the cycle length of the tachycardia to 400 ms without interruption. Considering the anatomy and previous reports of tachyarrhythmias originating from this structure or the related vein and ligament of Marshall,2–4 the giant left superior vena cava was mapped passing through the subclavian vein; the activation map showed the absolute earliest activation in a site facing the previous area of ablation in the LA. Radiofrequency ablation at this point stopped the tachycardia within 5 seconds (Figure 2). A total amount of 240 seconds of radiofrequency was delivered under power control titrated up to 35 W. At the end of the procedure, the tachycardia was no longer inducible, and the patient remained free of any arrhythmias during follow-up (12 months).
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Patients with congenital cardiomyopathy who have undergone a surgical procedure frequently develop atrial arrhythmias caused by circuits or focal mechanisms favored by the altered anatomy of the heart. For this reason, it is important to identify key anatomic variations inside a modified structure and to link this information with the electroanatomic map of the tachycardia. The CartoMerge Image Integration Software allows us to understand the mechanism of the arrhythmia and to guide the ablation with high accuracy and detail in a complex anatomy. In this case, the preacquired CT images and their segmentation were able to identify these anatomic structures. Without the CT images and the integration with the map, it would have been very difficult to identify the existence of the giant left superior vena cava and, therefore, the origin of the arrhythmia. This approach, as in this case, is a powerful and useful tool to understand and to treat these types of complex arrhythmias.
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Disclosures |
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S. Colombo is an employee of Biosense Webster. The remaining authors report no conflicts.
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References |
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