From Ask Dr Wiki
Free Wall Accessory Pathways
- Free wall accessory pathways are the most common positions for AP in clinical practice. Left Free wall pathways account for up to 60% of all pathways and right free pathways account for up to 20%.
- ECG negative delta in lead I and strongly positive delta in precordial leads.
- Success >95% with low recurrence.
- For Anterior or Anterolateral pathways use the retroaortic approach. For Posterior or posterlateral pathways use the transseptal approach.
Right sided Pathways
- ECG delta positive in lead 1 and aVL and negative in V1-V3.
- The amount the V electrogram precedes the delta is longer for right sided pathways compared to left sided pathways.
- To find the annulus the atrial electrogram is roughly 1/3 rd the V electrogram.
- For difficult cases, it may be neccessary to come from SVC for anterior right sided pathways and use a sheath
