AVNRT / AVRT Flashcards
What type of mechanism AVNRT?
Micro- Reentry
What are the two pathways of AVNRT?
Alpha & Beta
What is the Alpha pathway also known as?
Slow Pathway
Where is the slow pathway located?
Close to the CS os
Does the slow pathway have a long or short refractory period?
Short Refractory
What is the Beta pathway also known as?
Fast pathway
Where is the fast pathway located?
By the tricuspid annulus superior to the Triangle of Koch
Does the fast pathway have a long or short refractory period?
Long Refractory
What is the typical pathway for AVNRT?
Slow- fast
Explain the conduction of typical AVNRT.
Conduction antegrate down the slow pathway then retrograde up the fast pathway
What is the atypical pathway for AVNRT?
Fast- Slow
Explain the conduction of atypical AVNRT.
Conduction antegrate down the fast pathway then retrograde up the slow pathway
What does a short refractory period mean?
It means that it takes a shorter time until it is able to conduct again
What does a long refractory period mean?
It means it takes a longer time until it is able to conduct again
What does antegrate conduction mean?
Conduction from the atria to the ventricles
What does retrograde conduction mean?
Conduction from the ventricles to the atria
What are the treatment options for AVNRT?
RF ablation, Vagal Manuvers, Medication, or cardioversion
How do you induce AVNRT?
PES Pacing
How do you terminate AVNRT?
Adenosine
What is the end goal of a RF ablation for AVNRT?
Destroy the slow/ alpha pathway
How do you know if you RF ablation is successful in AVNRT?
A slow junctional rhythmn
*****What do you do if you see a fast junction rhythm after an ablation and what causes this?
Stop ablation and this is caused because you are too close to the AV node
What type of mechanism is AVRT?
Macro- reentry
What does AVRT use to get from the ventricles back to the atria?
The bundle of Kent
What is the most common form of AVRT?
Wolff- parkinson- white (WPW)
Is WPW an antidromic or orthodromic AVRT and why?
AVRT is an orthodromic AVRT because it had a narrow QRS
What are the indications of WPW?
A short PR interval and delta waves on the ECG.
Does orthodromic AVRT have a wide QRS or a Narrow QRS?
Narrow
Does orthodromic AVRT conduct antegrade or retrograde?
Antegrade
Does antidromic AVRT have a wide QRS or a Narrow QRS?
Wide
Does antidromic AVRT conduct integrate or retrograde?
Retrograde
What is the most common medication given to patients with WPW?
Amiodarone
Can a manifest pathway conduct antegrate, retrograde, or both?
Both
Can a concealed pathway conduct antegrate, retrograde, or both?
Retrograde only
Will you see delta waves on AVRT that has a manifest pathway, a concealed pathway, or both?
Manifest pathway only
What structures are involved in the AVRT circuit?
Atria, Ventricles, AV node, and AP
On an ECG how do you tell if the AP in AVRT is right or left sided?
A + delta wave on V1 means left sided, a - delta wave on V1 means right sided
(-) delta on V1 left or right sided?
right sided
(+) delta on V1 left or right sided?
Left sided
Left or right sided AP; “V” spike on HRA will proceed the “V” spike on HIS
Right sided
Left or right sided AP; “V” spike on the CS will proceed the “V: spike on HIS
Left sided
Left or right sided AP; VA interval increases with RBBB
Right sided
Left or right sided AP; VA interval increases with LBBB
Left sided
What is the goal on an ablation for AVRT?
Eliminate the delta wave
How do you terminate AVRT?
Adenosine
What catheters are used in an EP study for AVRT?
HRA, HIS, CS, RVA
Where do you ablate for AVNRT?
Below the AV node
What do you want to ensure you never do and why?
Ablate the HIS, this will cause a complete heart block and the patient will need a PPI
What are contraindications for preforming a carotid massage on a patient?
Stroke or TIA in the past 3 months, MI in the past 3 months, or coronary artery disease
What is the cardioverson energy used for AVNRT?
50-100J
How do you tell slow- fast AVNRT on an ECG?
P waves are hidden in the QRS
How do you tell fast- slow AVNRT on an ECG?
P waves are retrograde after the QRS
How do you tell if an EGM is displaying AVNRT?
There will be an AH jump, the V and A will line up, there will be a wide QRS
How do you tell the best place to ablate AVNRT based on an EGM?
There will be a fractionated signal on the ablation catheter
For AVRT if a patient asymptomatic would you proceed with an ablation?
No, only if the patient is not symptomatic
For WPW what is the first line of treatment if the patient is stable?
A cardioverson
What meds should you avoid in a patient with WPW?
dixogin, verapamil, diltiazem, and beta blockers
How do you induce AVRT?
PES Pacing
What population is AVRT most common in?
Younger men
On an EGM how do you know if you are in/ on the AP?
There will be a fusion
How do you know if you are testing for AP ERP on an EGM?
There will be an “A” spike but no “V” spike
what is parahisian pacing used for?
Helps differentiate septal AVRT from AVNRT