ECG Case 117

Rate:

Rhythm:

Axis:

Intervals:

• PR – Short (80ms)
• QRS – Prolonged (120ms)
• QT – 340ms (QTc Bazett 460 ms)

Segments:

• ST Elevation leads aVR, V1-2
• ST Depression leads I, II, III, aVF, V4-6

Additional:

• Delta waves best seen inferolaterally
• T wave inversion leads I, II, III, aVF, V3-6
• ‘Pseudo’ left ventricular hypertrophy
  • Prominent R waves leads I, II, III, aVF, V4-6
  • Deep S waves leads aVR, aVL, V1-2

Interpretation:

• Wolff-Parkinson-White syndrome
  • Right anteroseptal pathway – using Arruda algorithm
  • Voltage & ST/T changes secondary to pre-excitation
  • Patient requires referral for an EP study.

The right anteroseptal pathway can be difficult to ablate due to the close proximity of the AV node and risk of AV nodal injury during ablation.

Cryothermal ablation and careful mapping may be required rather than RF ablation. A more detailed review of septal accessory pathways and ablation techniques can be found here:

There are two commonly used algorithms to identify accessory pathway location from the surface ECG, the Arruda algorithm and Milstein algorithm. You can also download a free app called EP Mobile which incorporates both algorithm’s in addition to lots of other useful EP formulas (iTunes or Google play)