Differentials

Question 0

Junctional ectopic tachycardia

Answer 0

Narrow QRS complex with variable RR intervals

Abnormal automaticity

Question 1

Wide QRS Tachycardia

Answer 1

1. VT
2. SVT with aberrancy
3. Pre excited tachycardia
4. Paced rhythm
5. Artifact

Question 2

Outflow tract VT

Answer 2

Adrenergically mediated triggered activity caused by cAMP induced after depolarization

Adenosine sensitive

RVOT: LBB pattern with inferior axis

Question 3

Fascicular VT

Answer 3

Reentrant mechanism involving left fascicles (usually posterior)

RBBB morphology with left superior axis

Sensitive to verapamil (calcium dependent)

Question 4

Torsade de pointes

Answer 4

Initiated by subendocardial focal activity

Short-long-short RR pattern

Terminates due to further functional conduction block or wave front collision within ventricular myocardium

Question 5

Bidirectional VT

Answer 5

Seen in CPVT, Anderson-Tawil syndrome, and digitalis toxicity

Results from delayed after depolarization induced triggered activity alternating in left and right bundles

Question 6

Lev-Lenègre syndrome

Answer 6

Progressive cardiac conduction disease

Reduction of sodium entering the cell

SCN5A, NKX2.5