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What are the two different forms of tachycardia?
Give examples of Focal Tachycardias:
Atrial Tachycardia (inc SVT)
What are Focal Tachycardias Formed from?
What are the treatment options for focal tachycardia?
Treat underlying cause
What types of tachycardia does abnormal impulse conduction give rise to?
Examples of Re-entry Tachycardias are:
- Atrial Flutter
- AVRT (Assessory Pathways)
What care the prerequisites for re-entry?
Slow and fast pathway whereby one part has a faster/slower refractory
Explain normal physiological features of the AV node:
Fast Pathway with slow refractory
Slow pathway with fast refractory
What is this structure known as?
Triangle of Koch
Explain normal sinus rhythm with respects to the AV node:
Conduction comes to the AV node
Passes down both the fast and slow pathway
Fast pathway conducts quicker to the BoH
Slow pathway comes to BoH in refractory and can not conduct
How can a SVE cause a re-entry circuit?
Passes to AV node as normal but fast pathway is in refractory
Passes down slow pathway which conducts to the Ventricles and back up the fast pathway (retrograde) once it finishes refractory
Circuit commenses due to slow pathways fast refractory
Some symptoms of AVNRT include:
How is the retrograde P wave caused and why does it occur at same time of QRS:
Fast conduction up the AV node back to atria causes retrograde P wave
At same time impuse is sent to ventricles
What happens to the PR interval on AVNRT?
What can be done to stop AVNRT?
How do they help?
Carotid Sinus Massage
Increase parasympthetic activity
How does adenosine work?
Affects calcium dependent cells such as SA and AV node
What drug can cease AVNRT? And what does it effect on?
Adenosine acts on SA node and AV node
How would you suspect AVNRT on an EP study?
Atrial to BoH (AH interval)
What is RF ablation and how does it prevent AVNRT?
Positioned against slow pathway (posterior) and ablated
What rhythm is seen on RF slow pathway ablation?
Why should RF ablation be stopped if non-conducted P wave is seen?
Close to the AV nodal body