Utility of Cooled-tip Radiofrequency Ablation for Accessory Pathways Refractory to Standard Radiofrequency

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Citation
US Cardiology 2006;2005:2(1):167-168

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Accessory pathways are formed embryologically during cardiogenesis and may be broad, slanted, and occasionally particularly challenging to ablate. Right-and left-sided pathways are derived differently with right-sided pathways characteristically subendocardial as opposed to subepicardial. Successful ablation of right-sided pathways is frequently limited by catheter stability and ablation attempts are associated with a lower acute success and higher recurrence rate. The authors report a challenging case of a right-sided accessory pathway with interesting surface echocardiographic (ECG) manifestations, suggesting a long slanted pathway. Location and characteristics presented a challenge using standard ablation techniques and required complex catheter manipulation and cooled-tip energy application to create the effective lesion formation necessary for pathway elimination.

Background

The patient is a 17-year-old male who has been diagnosed with ventricular pre-excitation since the age of nine. Initially, he only complained of intermittent palpitations, but more recently demonstrated an adenosine-sensitive sustained supraventricular tachycardia. Although he was well controlled on ╬▓-blocker therapy, he was a competitive swimmer, and preferred non-pharmacologic curative therapy.

The patient underwent diagnostic electrophysiology testing eight months prior to the curative ablation. This evaluation diagnosed a manifest posteroseptal pathway (see Figure 1), and a concealed right free-wall (RFW) pathway. Unfortunately, ablation attempts were unsuccessful. A repeat procedure six months later was also unsuccessful, despite the use of a unidirectional cooled-tip catheter.

Eight months after the initial procedure the subject presented for repeat electrophysiology testing and ablation at the authorsÔÇÖ institution.

Electrophysiology Study
  • Written informed consent was obtained.
  • Conscious sedation was used throughout the procedure.
  • Diagnostic catheters were placed in the coronary sinus.
  • The subjectÔÇÖs bundle position, tricuspid annulus (Halo), and right ventricle (RV) and the electrophysiologic properties of the pathway were assessed.
  • Earliest antegrade activation appeared to be in the distal halo (see Figure 2).
  • Pacing the RV demonstrated earliest retrograde activation in the low lateral right atrium.

 

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