Ventricular Arrhythmias

Question 1

The two major characteristics of premature ventricular complexes (PVCs) are ?

Answer 1

1) Premature timing : They occur before the next normal beat is expected.
2) Aberrant QRS-T appearance : the QRS complex is abnormally wide (120 ms or more) and the T wave and QRS complex usually point in opposite (discordant) directions.

Question 2

How do you define ventricular tachycardia ?

Answer 2

Three or more PVCs in a row are, by definition, VT.

Question 3

PVCs originating in the area of a post-MI scar often have a…?

Answer 3

QR configuration. (Finding this in multiple leads should make you suspect an underlying infarct even when no Q waves are seen).

Question 4

Major settings where R on T beats may precipitate sustained VT or VF ?

Answer 4

Acute MI, Long QT interval syndrome, Commotio Cordis syndrome, During direct current DC cardioversion, if the depolarizing stimulus is not synchronized with the QRS complex.