Classic tachycardias of WPW accessory pathways

• Orthodromic AVRT: narrow-complex SVT (typically), conducting ↓ AVN & ↑ accessory pathway; requires retrograde conduction and ∴ can occur w/ concealed bypass tracts
• Antidromic AVRT (rare): wide-complex SVT, conducting ↓ accessory pathway & ↑ AVN; requires antegrade conduction and ∴ should see pre-excitation pattern during SR
• AF w/ rapid conduction down accessory pathway; ∴ wide-complex irregular SVT; requires antegrade conduction; ∴ should see pre-excitation in SR. Rarely can degenerate into VF.

(1) type A 型：是在 V1V6 lead 的 Delta wave 都是 upright positive ；因為 accessory pathway 的傳導性衝動是由 LA 後壁進入 LV 後壁，因此在 lead V1 的 R 會比 S 大； (2) type B 型：的 Delta wave 是負向的，因此，在 V1 和 V2 lead 會有 negative 的 Delta wave 和 QRS complex，這是因為 accessory pathway 的衝動，由 RA 後面或側面進入 RV，所以 V3-V6 的 Delta wave/QRS complex 都是 upright positive，但 V1V2 是 negative。

不要用ABCD四大類藥物