Ventricular arrhythmias Flashcards
What are premature ventricular beats also referred to as?
Premature ventricular contractions (PVCs)
PVCs are early ventricular beats in the cardiac cycle.
What characterizes PVCs that originate from the same focus?
They have the same QRS morphology and are referred to as unifocal
Unifocal PVCs indicate a single ectopic focus.
What defines multifocal PVCs?
They originate from different ventricular sites and have different QRS morphologies
Multifocal PVCs suggest multiple ectopic foci.
What are two consecutive ventricular beats called?
Ventricular couplets
Couplet indicates a pairing of premature ventricular beats.
Fill in the blank: PVCs that originate from the same focus are referred to as _______.
unifocal
True or False: All PVCs have the same QRS morphology.
False
Only unifocal PVCs share the same morphology; multifocal do not.
What is ventricular tachycardia (VT)?
Three or more consecutive beats at a rate faster than 100 beats/min
What is the designation for three or more consecutive beats at slower rates than VT?
Idioventricular rhythm
What is non-sustained VT?
VT that terminates spontaneously within 30 seconds
What is sustained VT?
VT that persists for >30 seconds or is terminated by an active intervention
Name one method to terminate sustained VT.
Administration of an intravenous medication
Other methods include external cardioversion, anti-tachycardia pacing, or a shock from an implanted cardioverter defibrillator.
What does monomorphic VT indicate about the QRS complex?
The same QRS complex from beat to beat
This indicates that the activation sequence is consistent and likely originates from the same source.
What largely determines the sequence of ventricular activation?
The initial site of ventricular activation
This site influences the morphology of the QRS complex.
What does the QRS morphology of PVCs and monomorphic VT indicate?
The site of origin within the ventricles
This information can suggest whether an arrhythmia is idiopathic or associated with structural disease.
What is the characteristic of arrhythmias originating from the right ventricle or septum?
Late activation of much of the left ventricle
This results in a prominent S wave in V1, resembling a left bundle branch block–like configuration.
What morphology is produced by arrhythmias originating from the free wall of the left ventricle?
Right bundle branch block–like morphology in V1
This is indicated by a prominent positive deflection in V1.
What does a frontal plane axis directed inferiorly suggest?
Initial activation of the cranial portion of the ventricle
This is indicated by dominant R waves in lead II, III, and AVF.
What does a frontal plane axis directed superiorly indicate?
Initial activation at the inferior wall
This is indicated by dominant S waves in II, III, and AVF.
