Tachyarrhythmias

Question 1

Premature Atrial Contraction (PAC)

Answer 1

early atrial depolarization: can be bigeminal/trigeminal
P-Wave morphology may be different (coming from different site)
May be nonconducted
Asymptomatic, usually self-limited

Question 2

Sinus Tachycardia

Answer 2

Arrives from Sinus Node
In adults, HR over 100 bpm
P-Wave always followed by QRS complex 1:1 fashion
Occurs as a physiologic response (i.e. stress, exercise)

Question 3

Supraventricular Tachycardia

Answer 3

Narrow QRS- 140-240 bpm
Abrupt onset and offset
P-Wave buried in the QRS, morphology is different
Caused by accessory pathway:
Within AV Node= AV Nodal Reentry Tachycardia 2/3 of pts
Outside of AV Node through Bundle of Kent=AVNRT 1/3 of pts
Terminate with Adenosine

Question 4

AV Reentry Tachycardia

Answer 4

PAC arrives while accessory pathway is still in refractory
Activates AV Node slowly
Once signal reaches ventricle, accessory pathway is recovered and transmits signal retrograde to the Atria
Atria reactivates ventricle through AV Node

Question 5

Wolff Parkinson White (WPW)

Answer 5

Delta Wave-slurred upstroke of QRS= pre-excitation in location of the accessory pathway, while conducting through the AV Node in sinus rhythm.
Narrow PR Interval in Sinus
Accessory Pathway leads to SVT
Pt must have SVT, symptoms, and Delta Wave on EKG to be diagnosed.

Question 6

AV Nodal Reentry Tachycardia (AVNRT)

Answer 6

Dual AV Nodal Physiology:
Slow Pathway-slow conducting with fast recovery
Fast Pathway-fast conducting with slow recovery
Normal is only 1 pathway present (fast)

Question 7

Atrial Tachycardia

Answer 7

Originates in the atria, but outside of the sinus node.
Rate is faster then sinus, takes over pacemaker
Caused by atrial scarring, drugs (digoxin)
140-200 bpm
P-Wave is buried in T-Wave

Question 8

Multifocal Atrial Tachycardia

Answer 8

Multiple ectopic foci in the atria firing
Multiple P-Wave morphologies
100-150 bpm
Most common cause is COPD
Thought as a transitional arrhythmia from atrial tachy to A-Fib

Question 9

Atrial Fibrillation

Answer 9

irregularly irregular
usually over 100 bpm, but can be slower
No organized atrial rhythm, no discernable P-Waves, atria firing 300-600 bpm
Most Common Chronic Arrhythmia
Atria are shaking, quivering but ventricles can’t contract/conduct because AV Node refractory period

Question 10

Atrial Flutter

Answer 10

Reentrant circuit in atria
sawtooth pattern in inferior leads
Typical Flutter: short reentrant circuit within the RA, ventricular response is regular 2:1, 3:1, 4:1
Atypical Flutter: reentrant circuit in the atria from any other location in the atria

Question 11

Premature Ventricular Contractions (PAC)

Answer 11

Wide QRS beats usually without P-Wave

Bigeminal/Trigeminal

Question 12

Ventricular Tachycardia

Answer 12

3 or more PVCs, 160-200 bpm
Nonsustained:more than 3 beats but less than 30 seconds before terminating spontaneously
Sustained: over 30 seconds in duration and/or requiring cardioversion due to instability
Treatment based on hemodynamic stability:
-Stable:treat with medication, IE Beta Blocker, antirrhythmic drugs
-Unstable:cardioversion emergently

Question 13

Monographic VT

Answer 13

most likely due to a reentrant circuit within the ventricle, commonly caused my myocardial scarring

Question 14

Polymorphic VT

Answer 14

more omnious, much more electrically unstable ventricle

Question 15

Torsades de Pointes

Answer 15

form of Poly VT, occurs in the setting of long QT Interval
“twisting of the point”-twisting of the QRS complex along isoelectric baseline
Occurs in Complete Heart Block
Requires emergent defib; leads to suddent cardiac death

Question 16

Ventricular Fibrillation

Answer 16

No discernable activity; 200-300 bpm if you could count
Patient is pulseless
Cause death unless quickly resuscitated-next step asystole-flat line
Requires defib as quickly as possible