AVRT / FLUTTER / SVT Flashcards
What are the 4 types of bypass tract in AVRT
1 - AV Bypass Tract
2 - Compact AVN
3 - Atrium to BB - AKA Mahaim
4 - His Purkinje
What is the orthodromic VA conduction time of AVRT
> 80ms
Give 5 differential diagnosis of SVT
1 - AVRT 2 - AVNRT 3 - A Flutter 4 - Ectopic A-Tachy 5 - Junctional / His Tachy 6 - Sinus Node Re-entrant Tachy
Is AVRT micro or macro re-entry
MACRO
AVNRT is micro
If conduction occurs in both directions, whats it called
Overt / Manifest
If conduction is VA only, whats is called
Concealed
Whats the incidence of WPW
3/2000
What is an ECG hallmark of WPW during antegrade conduction
Delta wave
What is a delta wave
Slowed conduction through myocadial tissue which attach to the accessory pathway.
Once normal conduction catches up, the QRS narrows
What does a latent pathway possess
Slow conduction properties
How does a latent pathway appear on ECG
Looks normal on ECG
What percentages of WPW are Right and Left
60-70% are Left sided
20% are Right sided
If the delta wave is + in V1 and V2, which side is the AP
+ in both = Left sided
If the delta wave is - in V1 and V2, which side is the AP
- in both = Right sided
If the delta wave is - in V1 and + in V2, which side is the AP
- in V1 and + in V2 = Septal
Do pathways have decremental conduction proporties
No - they’re all or nothing
What does the HV interval look like in WPW
Abnormally short
What does the AV interval look like in WPW
Normal but very early
Is orthodromic clockwise or anticlockwise
ANTIclockwise
Is Antidromic clockwise or anticlockwise
CLOCKWISE
Which is more common Orthodromic or Antidromic AVRT
Orthodromic is common / Antidromic is rare
Which direction of AVRT give narrow complex QRS
Orthodromic (Anticlockwise) gives narrow QRS
Which direction of AVRT gives broad complex QRS
Antidromic (Clockwise) gives broad QRS
When ablating an Accessory pathway, what signal do you look for
Earliest V signal, pre-delta wave
Should you ablate during tachy? Why?
No - Sudden termination of tachy dislodges the catheter and may result in damage to the surrounding tissue
Does VA time change during ablation? What happens and why?
Yes - It slowly lengthens until it blocks completely. Lengthening is a good sign for ablation as it signifies local tissue damage
Why is AF a problem in WPW
Due to a lack of decremental properties - the AF will be conducted 1:1. Such a quick V rate can lead to VF
AF with WPW is called
Pre-excited AF
Why is AF without WPW not as big of a problem
The AV node decrements and acts like a gatekeeper for fast rhythms - Thus V rate remains low and stable.
Is Flutter a micro or macro re-entry tachycardia
Macro around the RA
Flutter in an anticlockwise direction is
Typical
Typical flutter accounts for what percentage of all Flutter
90%
Reverse typical flutter flows in which direction
Clockwise
Which direction of flutter is Isthmus dependant
Typical
Reverse typical flutter flows around which structure
Tricuspid valve annulus
What rate is flutter
300bpm (240-350bpm)
P-waves are negative in INF leads / Positive in V1 - what direction is this?
Typical
P-waves are positive in INF leads / Negative in V1 - what direction is this
Reverse Typical
