Thread by @veramasloo

Tweetorial, 1/8
40 yo,male, narrow QRS tachycardia 170 bpm.
Check out step by step EP diagnostic algorithm for narrow complex tachy!
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2/8
1⃣VA=110 ms(> 85 ms)➡️AVRT or atypical AVNRT or AT with unusually long AV conduction
2⃣Termintion of tachycardia
✅Termination with AV➡️AT or AVNRT or AVRT

3/8
3⃣Decremental RV pacing:
✅Nondecremental Conduction➡️via accessory pathway (AP)

4/8
4⃣Preceding maneuver
His refractory premature ventricular stimulus (PVS) during tachycardia (prevents retrograde atrial activation via His)
❌PVS doesn’t precede the atrium➡️no AP
✅PVS advanced next atrium activation➡️AP

5/8
5⃣RV-entrainment
✅Response: VAV➡️excludes AT➡️our tachy is AVNRT or AVRT
✅PPI-CL=446-340ms=106 ms < 115ms ➡️AVRT

6/8
6⃣Parahisian Pacing
at high output(capture both RV and HB), then at low output (loss of HB capture, note the nice retro His)
✅Stim-A time similar➡️presence of AP
❌Stim-A time increase without change His-A ➡️AVN conduction

7/8

8/8
AP ablation abolishing the VA conduction