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Flashcards in Preexcitation & SVT Deck (81)
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1

What are the 2 possible electrical pathways to the ventricles?

1. Normal AV node

2. "abnormal" accessory pathways

2

The most common electrical pathway to the ventricles is through the AV node. The normal AV node to the pathways is referred to as?

alpha pathway

3

Current can travel through abnormal conduction pathways that are referred to as ______ pathways

beta

4

Where are the 2 places beta pathways can be found?

AV node
Myocardium

5

4 other names for the abnormal beta conduction pathways

1. accessory pathways
2. bypass tracts
3. Preexcitation pathways
4. Aberrant pathways

6

normally current travels down the normal ____ _____ ______, because the _____ _____ are usually not dormant/active

av node pathway

beta pathway

7

If the beta pathways become active for some reason, what is the patient at risk for?

arrhythmias

8

What are 4 triggers that can activate the beta pathways?

1. stress, catecholamine surges
2. caffeine, tobacco, street drugs
3. electrolyte abnormalities
4. acid-base imbalance

9

When a beta pathway is activated, does the current stop going through the alpha pathway?

no

10

When a beta pathway is activated, the current will go through (beta, alpha, both) pathway(s)

Both

11

When current travels down the normal AV node (alpha) pathway it has:

1. (slow/rapid) conduction

2. (long/ short) refractory period

1. SLOW conduction
-slower conduction allows for optimal ventricular filling before ventricular contraction

2. SHORT refractory period (fast reset)
-the normal AV node pathway does not have to rest long before it can depolarize again (can depolarize faster)

12

When current travels down the abnormal Beta pathway it has:

1. (slow/rapid) conduction

2. (long/ short) refractory period

1. RAPID conduction
-conduction is faster than the regular AV node path, but still slower than electrical conducting cells

2. LONG refractory period
-slow reset

13

What will the PR interval look like if an accessory pathway IN THE AV NODE is activated? (normal, short, or prolonged?)

short PR interval

14

What will the QRS complex look like if an accessory pathway IN THE AV NODE is activated? (normal or wide?)

normal QRS interval
-the impulse still travels down the normal electrical pathway after the AV node

15

What will the PR interval look like if an accessory pathway IN THE MYOCARDIUM is activated? (normal, short, or prolonged?)

short PR interval

16

What will the QRS complex look like if an accessory pathway IN THE MYOCARDIUM is activated? (normal or wide?)

wide; with a delta wave
*The upper ventricle is depolarized by the myocardium and this is slow conduction

*The rest of the ventricle is depolarized by the purkinjie system (fast conduction)

17

Because current travels faster through the _____ pathways, the ventricles will contract earlier than expected

beta

18

The term that refers to the ventricles depolarizing earlier than they are supposed to

Pre-excitation

19

anytime current travels down the _____ pathway, preexcitation will occur

beta

20

Should we be concerned with pre-excitation from activation of the beta pathway?

What is really the only clinical significance of pre-excitation with an otherwise normal sinus rhythm?

no

the ventricle may just have slightly less optimal filling time; shorter PR interval
(due to earlier ventricular contraction)

21

If pre-excitation is associated with _____, the abnormal beta pathways can form reentrant loops that can lead to _______

tachycardia

arrhythmias

22

What is the common arrhythmia that pre-excitation from abnormal pathways can lead to?

supra ventricular tachycardia (SVT)

23

If a premature atrial contraction (PAC) occurs in a patient with an activated beta pathway, which path will the current travel through to get to the ventricles? The alpha pathway or the beta pathway?

ANTEGRADE through the slow Alpha pathway ONLY
-the accessory pathway from the previous beat is still refractory due to its long refractory period)

24

When does the accessory pathway repolarize after a PAC?

When the impulse is traveling down the slow AV node

25

In a PAC:
When the impulse gets to the ventricles (after traveling through the alpha pathway), it can now travel (antegrade/retrograde) through the ______ pathway

retrograde
fast accessory pathway
(the accessory pathway has re-polarized at this point)

26

In a PAC:
After the impulse has traveled retrograde though the accessory pathway, the impulse can now travel (antegrade/ retrograde) down the _______ pathway

antegrade

slow Alpha pathway
(the refractory period is short)

27

The activated accessory pathway in a patient with PAC creates a continuous reentrant _______ loop

tachycardic

28

What type of arrhythmia does the reentrant tachycardic loop cause?

supra ventricular tachycardia

29

In PAC with activation of the accessory pathway, the tachycardic loop (re-entry) is in the myocardium, which causes (wide/narrow) QRS and a _____ wave to be seen on the ECG

wide
delta

30

In PAC with re-entry in the AV node, the QRS will be (normal/wide)

normal (narrow)