SFP: reentrant arrhythmia

Question 1

What is SVT?

Answer 1

Abnormally rapid heart rate that originated above the ventricles.

Question 2

What is the most common arrhythmia in pediatrics?

Answer 2

SVT.

Question 3

What is atrial flutter?

Answer 3

Reentrant circuit in the right atrium.

Question 4

What is AVNRT?

Answer 4

Reentrant circuit at the AV node.

Question 5

What is atrial tachycardia?

Answer 5

Ectopic focus (not sinus node); somewhere else in the atria is sending an electronic impulse.

Question 6

What is antidromic AVRT?

Answer 6

Impulse goes down the accessory pathway and back to the AV node.

Question 7

What is orthodromic AVRT?

Answer 7

Impulse goes out of the AV node and through the accessory pathway.

Question 8

Describe focal autonomic tachycardia (atrial tachycardia).

Answer 8

A non-reentrant arrhythmia that features a wide variation in rate that correlates with sympathetic tone. It cannot be initiated with stimulation and is not terminated with shock.

Question 9

What can be associated with supraventricular tachycardia?

Answer 9

Premature atrial complex.

Question 10

What is a reentrant arrhythmia?

Answer 10

Excitation wavefront traverses tissue and reactivates the same tissue.

Question 11

What must be true for a reentrant arrhythmia to occur?

Answer 11

1. There must be 2 discrete pathways. 2. Wavefront must be delayed somewhere to allow the original tissue to recover. 3. 2 pathways must have different conduction properties and refractoriness.

Question 12

What are clinical features of reentrant tachycardia?

Answer 12

Very regular rate with abrupt onset and cessation. It is easily initiated with programmed stimulation and easily terminated with shock. Antiarrhythmic drugs are useful.

Question 13

What causes accessory pathway mediated tachycardia?

Answer 13

Electrical contact between atrial and ventricular myocardium is disrupted by an ingrowth of the AV sulcus and formation of annulus fibrosis; causes persistent pathological electrical continuity that allows accessory pathway conduction.

Question 14

What is Wolff-Parkinson-white?

Answer 14

An accessory pathway mediated tachycardia with anterograde conduction and ventricular pre-excitation.

Question 15

How does WPW cause tachycardia?

Answer 15

During refractory period, the impulse generates does not travel through the accessory pathway anymore and returns to following the AV node. This will result in tachycardia.

Question 16

What is a concealed accessory pathway?

Answer 16

There is only retrograde conduction; the true incidence of it is unknown.

Question 17

What would an accessory pathway mediated tachycardia look like on EKG?

Answer 17

No delay at the AV node due to accessory pathway use causes preexcitation. This widens the QRS and causes a delta wave at the beginning of the QRS.

Question 18

How do we treat AP mediated tachycardia?

Answer 18

Observation, drugs, anti-tachycardia pacing, ablation.

Question 19

What is the typical treatment of WPW?

Answer 19

Ablation.

Question 20

Describe AVNRT.

Answer 20

AV nodal reentry involves 2 discrete pathways: a fast and a slow. The fast pathway has a shorter conduction time and a longer refractory period, while the slow pathway has a longer conduction time and shorter refractory period. There is a cycle back and forth between these.

Question 21

What is the most common form of SVT in adults?

Answer 21

AVNRT.

Question 22

In AVNRT, what pathway are we trying to knock out with ablation?

Answer 22

The slow pathway found in the triangle of Koch.

Question 23

Describe presentation of AVNRT.

Answer 23

Activity and posture can incite symptoms, and it has abrupt onset and resolution.

Question 24

The Valsalva maneuver and carotid massage can help manage which reentry tachycardia?

Answer 24

AVNRT.

Question 25

What is the major pharmacologic treatment of AVNRT?

Answer 25

Adenosine.

Question 26

What does adenosine do in AVNRT?

Answer 26

Terminates tachycardia.

Question 27

What does adenosine do in AP mediated tachycardia?

Answer 27

Terminates tachycardia.

Question 28

What does adenosine do in atrial tachycardia?

Answer 28

Increases AV block with continuation of atrial tachycardia; not an AV nodal issue so adenosine doesn’t stop it.

Question 29

What does adenosine do in atrial flutter?

Answer 29

Increased AV block with continuation of atrial flutter; atrial flutter isn’t an AV nodal issue so adenosine doesn’t stop it.