Preexcitation & SVT Flashcards
(52 cards)
2 possible pathways to the ventricles
- Normal AV node pathway
2. “abnormal” accessory pathway
What is the alpha pathway?
The normal AV node pathway
What is the beta pathway?
The abnormal conduction pathways in the AV node or myocardium
Other names for beta pathways
- Accessory pathways
- Bypass tracts
- Preexcitation pathways
- Aberrant pathways
What happens if a beta pathway is activated?
The pt is at risk for developing arrhythmias
Possible triggers that can activate beta pathways
- Stress, catecholamine surges
- Caffeine, tobacco, street drugs
- Electrolyte abnormalities
- Acid-base imbalance
In normal conduction, if a beta pathway is activated, where does the current go?
In both the alpha and beta pathways
What kind of conduction and refractory period does the alpha pathway have?
- Slow conduction
2. Short refractory period (fast reset)
What kind of conduction and refractory period does the beta pathway have?
- Rapid conduction
2. Long refractory period (slow reset)
What will the PR interval look like if the accessory pathway in the AV node is activated?
Short
What will the QRS complex look like if an accessory pathway in the AV node is activated?
Normal
What will the PR interval look like if an accessory pathway in the myocardium is activated?
Short
What will the QRS complex look like if an accessory pathway in the myocardium is activated?
Wide
What occurs anytime current travels down a beta pathway?
Preexcitation
What is the clinical significance of preexcitation?
Not a big deal unless associated with tachycardia
-can lead to arrhythmias such as SVT
From a PAC with an activated beta pathway, which path will the current travel through to get to the ventricles?
Alpha pathway only bc the beta pathway is still in refractory
After the PAC impulse gets to the ventricles, what pathway does it travel?
The rapid beta pathway
If the reentrant tachycardic loop occurs in the myocardium, what would you expect to see on the EKG?
A delta wave and wide QRS complex
What accessory path is activated in Wolff Parkinson White syndrome?
The Kent bundle in the myocardium that forms a direct connection between the atria and ventricle
What does the EKG of WPW have?
- Short PR interval
2. Delta wave
When is WPW symptomatic?
With tachycardia
Anesthetic management of symptomatic WPW w/tachycardia
Avoid/limit sympathetic stimulation (ketamine, pain, hypovolemia, anxiety)
What can WPW with tachycardia be confused with on the EKG?
Vtach due to the wide QRS
Treatment for symptomatic WPW
- Transvenous catheter ablation
- Antiarrhythmic drugs (beta blockers, amiodarone)
- Synchronized cardioversion (if tachycardic and unstable)