L19

Question 1

What is the difference between SVT and paroxysmal?

Answer 1

SVT = constant
Parox = comes and goes

Question 2

What is the measurement for a narrow QRS?

Answer 2

Less than 3 boxes

Question 3

What does a narrow QRS imply?

Answer 3

Supraventricular tachycardia

B/c indicates ventricular activation is happening via the normal conduction system

Question 4

What does a wide QRS imply?

Answer 4

Ventricular activation is slow - not happening through normal conduction system (fast)
2 differentials
1. Ventricular tachy - TREAT AS SUCH
2. Supraventricular tachycardia with aberrancy

Question 5

Which is more worrisome: wide or narrow QRS?

Answer 5

Wide!

Ventricular abnormalities are more likely to be lethal

Question 6

3 mechanisms of arrhythmias

Answer 6

1. Re-entry
2. Enhanced automaticity
3. Triggered arrhythmias

Question 7

What is the common mechanism for these arrhymthias: AVNRT, AVRT, Aflutter?

Answer 7

Re-entry

Question 8

What is the arrhythmia mechanism for Torsade de Pointes?

Answer 8

Triggered - early afterdepol

- During phase 3 of the AP

Question 9

A 25-year-old male presents to the emergency department complaining of palpitations. He feels anxious, lightheaded, and short of breath. Current EKG reveals a narrow-complex supraventricular tachycardia. Looking back at his medical records, you find a baseline EKG from a prior visit when he had arrived at the ED just following resolution of his symptoms. Baseline EKG is significant for a short PR interval and a wide QRS complex with an initial slurring, or delta wave. Diagnose.

Answer 9

Wolf Parkinson White
- Type of AVRT
= supraventricular tachycardia resulting from pre-excitation of the ventricle due to accelerated conduction along an accessory atrioventricular (AV) pathway that bypasses the AV node

Question 10

What does a WPW EKG look like?

Answer 10

a wide QRS with initial slurring (delta wave) + sinus rhythm + short PR

• Delta = slurred upstroke of Q-wave as result of partial depolarization prior to normal conduction depolarization
• Wide QRS = extra current is not using the normal conduction system, instead conducting cell-cell = takes longer, widens QRS
• Short PR int = bypassing AV node conduction through atria

Question 11

What is the arrhythmia mechanism for sinus tachycardia?

Answer 11

Enhanced automaticity

Question 12

What situation would WPW be lethal?

Answer 12

WPW + Afib

Afib could cause Vfib through bypass tract

Question 13

What is inappropriate sinus tachy? Pt population? Treat

Answer 13

Young women
Inappropriate response to normal catecholamine release
Get increased atrial HR sitting down
Treat: BB or ablation

Question 14

3 mechanisms for paroxysmal supravent tachy

Answer 14

1. AV nodal re-entrant tachy = AVNRT
2. AV reciprocating tachycardia = AVRT
3. Atrial tachycardia not from sinus node

Question 15

Describe AVNRT

Answer 15

Early beat travels to AV node
Blocked in the slow pathway because this pathway is still repolarized from the last normal beat
So this early beat goes down the fast pathway
But by the time it finishes that pathway, the slow option is ready so the current continues in a loop
You only need 1 extra beat to start this - and thus you only need 1 extra beat to stop it

Question 16

What is the general idea behind AVRT?

Answer 16

There is an additional conduction pathway that bypasses the AV node to connect the atria and ventricles

Question 17

What is orthodromic supraventricular tachycardia?

Answer 17

Early beat goes through AV node
Abnormal re-entry through bypass tract to re-stim AV node
SEE narrow QRS

Question 18

What is anti-dromic orthodromic supraventricular tachycardia?

Answer 18

Wide QRS - b/c not using normal conduction
Early beat is block by AV node refractory period
Goes through bypass tract
Comes back up Purk/HIS to re-enter AV node

Question 19

How do you treat acute paroxysmal SVTs? (AVRT. AVNRT, AT)

Answer 19

Vagal maneuvers to skip 1 beat and reset the system
Adenosine
Cadioversion - only if hemodynamically unstable

Question 20

How do you treat chronic paroxysmal SVT?

Answer 20

Block AV node = BB or Ca channel blockers

1st choice = ablation = remove the bypass tract or 2nd arm of AV node

Question 21

What is Aflutter? Describe EKG.

Answer 21

Looping electricity confined to atira

Atria beat at 180-350 bpm with identical, back-to-back atrial depolarization waves = saw tooth!!!

Question 22

Treat Aflutter

Answer 22

Anticoag + AV node blockers
- BB or Ca channel blockers
- Net slow ventricular rate
Ablation

Question 23

What is the EKG pattern for AFib?

Answer 23

no discrete P waves
irregularly spaced QRS complexes
- Atria beat at 350-600 bpm with chaotic and erratic baseline (irregularly irregular)

Question 24

What are you worried about with AFib?

Answer 24

Can cause atrial stasis resulting in thrombus formation may lead to stroke
ANTI COAG ALL PTS

Question 25

What determines ventricular rate in AFib?

Answer 25

AV node refractory period

Question 26

Treat AFib?

Answer 26

Rate or rhythm control OR ablation 
Rate
- Ca channel blockers
- BB
- Ablate AVN, + pacemaker
Rhythm 
- Type 1 or 3 anti-arrhythmics

Question 27

Which pts do you never give type 1 anti-arrhythmics to?

Answer 27

Pts w/ structural heart disease

Question 28

What drugs to you give to pts with AFib + decreased LV fxn?

Answer 28

Amiodarone
Dofetilide
(Type 3s)

Question 29

Where do you ablate for AFib?

Answer 29

Atrial outgrowth around pulm veins