A 36-year-old male, who underwent Mustard correction for d-transposition of the great arteries (d TGA) at the age of 1 and received a mechanical valve in the tricuspid position (St Jude Medical 31 mm) at 25 due to valve insufficiency, was admitted to our center for catheter ablation of paroxysmal atrial tachycardia. While he remained stable until the age of 35, later he experienced recurrent symptomatic arrhythmias resistant to pharmacotherapy.
Echocardiography revealed post-Mustard correction anatomy without additional abnormalities. Three-dimensional CT displayed a mechanical valve in the tricuspid position, oriented perpendicularly to the sternum (Figure 1A).
The ablation procedure, performed under general anesthesia, utilized the Genesis Robotic Magnetic Navigation System (Stereotaxis, St Louis, MO, US) and a 3D system (CARTO 3, Biosense Webster, Irvine, CA, US).
After double access from the right femoral vein, a deflectable 4-pole, 7F diagnostic catheter (Marinr, Medtronic, US) was placed into the baffle. A transbaffle puncture was conducted under transesophageal echocardiography. Subsequently, the Thermocool RMT ablation catheter (Biosense Webster, US) was advanced to the pulmonary venous atrium (Figure 1B). Bipolar voltage mapping during sinus rhythm was performed (Figure 1C). Due to concerns about catheter entrapment, a Pentaray catheter was not used. Programmed stimulation induced atrial tachycardia (AT) with a cycle length of 240 ms and 1:1 conduction to the ventricle.
Entrainment techniques revealed AT dependence on the cavotricuspid isthmus (CTI). Due to the large scar on the right free wall, we were not able to locate the His bundle. Since that block in the CTI in patients after the Mustard correction often requires radiofrequency (RF) delivery in the venous atrium and the baffle, we performed an ablation line from the scar to the mechanical valve in the tricuspid position on the right free wall (Figure 1D).
During the RF application at 48°C and 50 W, the cycle length of AT gradually increased, and sinus rhythm was restored (Figure 1E). The bidirectional block in the created line was confirmed.
Despite an aggressive stimulation program, including up to 3 extra stimuli and burst pacing with and without isoproterenol infusion, no arrhythmias could be induced. The total procedure time and RF time were 360 minutes and 50 minutes, respectively. X-ray exposure was 4.44 mGym2, and fluoroscopy time was 23 minutes. Over 11 months of follow-up, no arrhythmias recurred.
In patients with d TGA, the arterial switch has replaced the atrial switch as the preferred surgical procedure, but most adults today have the Mustard or Senning correction, leading to arrhythmias becoming a significant clinical problem [1]. Catheter ablation, though challenging, can be successful [2–4].
This report represents the first successful transbaffle ablation of AT using robotic magnetic navigation (RMN) in a patient with a mechanical valve in the tricuspid position and after Mustard correction for d TGA. The procedure appears to be feasible, safe, and effective.
We have decided to use RMN because, in patients after Mustard correction, some areas in the pulmonary venous atrium are difficult to reach with the manual transbaffle ablation approach. The implementation of the transbaffle puncture technique and RMN offers a promising avenue for successful ablation of arrhythmias, even in the presence of a mechanical valve in the tricuspid position and Mustard anatomy.
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Funding: None.
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