Accessory pathways are formed embryologically during cardiogenesis and may be broad, slanted,1 and occasionally particularly challenging to ablate. Right-and left-sided pathways are derived differently with right-sided pathways characteristically subendocardial as opposed to subepicardial.2 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.3,4 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.
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.
- 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 (see Figure 3).
- Otomo K, Gonzalez M D, Beckman K J et al.,Reversing the direction of paced ventricular and atrial wavefronts reveals an oblique course in accessory AV pathways and improves localization for catheter ablation, Circulation (2001);104: pp. 550-556.
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- Twidale N,Wang X Z, Beckman K J et al.,Factors associated with recurrence of accessory pathway conduction after radiofrequency catheter ablation, PACE (November 1991);14(11 Pt 2): pp. 2,042-2,048.
- Chen Y J, Chen S A,Tai C T et al.,Long-term results of radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome, Zhonghua Yi Xue Za Zhi (Taipei) (February 1997);59(2): pp. 78-87.
- Arruda M S, McClelland J H,Wang X et al.,Development and validation of an ECG algorithm for identifying accessory pathway ablation site in Wolff-Parkinson-White syndrome, J. Cardiovasc. Electrophysiol. (January 1998);9(1): pp. 2-12.