AVNRT and AVRT

Question 1

In Normal Sinus Rhythm (AVNRT)

Answer 1

• AP goes through fast pathway to hit His Purkinje system

Question 2

When an atrial ectopic beat occurs

Answer 2

• Wavefront reaches pathways while fast is still refractory from the previous beat
• Wavefront must use the slow pathway
• Once it reaches HPB, fast pathway is no longer refractory
• Wave travels back up the fast pathway

Question 3

AVRT

Answer 3

• There is an accessory pathway
• Antegrade conduction from atria to ventricles, bypassing the AVN
• AP wavefront uses slow cell-cell activation and the QRS complex is broad

Question 4

AVRT- Orthodromic

Answer 4

• Narrow complex tachycardia
• Most commonly seen
• WF goes down normal pathway, then back up the re-entry pathway

Question 5

AVRT- Antidromic

Answer 5

• Very broad complex tachycardia

- WF goes down accessory pathway and back up to node

Question 6

Focal atrial arrhythmia

Answer 6

• Disorder of impulse formation
• Spreads from one point in the atrium
• Can increase OR decrease in speed

Question 7

Mechanism for FAA

ECG finding

Answer 7

• Micro re-entry tachycardia (around scarring from ablation/MI)
• P wave negative in leads I and II (originating far from the SAN)