C o m p e t e n c e i n E C G D i a g n o s e s

Lesson VI - ECG Conduction Abnormalities
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The above ECG shows classic RBBB (note rSR' in V1) plus
LAFB (note QRS axis = -45 degrees, rS in II, III, aVF; and
small q in aVL).
Nonspecific Intraventricular Conduction Defects (IVCD)
QRS duration >0.10s indicating slowed conduction in the ventricles
Criteria for specific bundle branch or fascicular blocks not met
Causes of nonspecific IVCD's include:
Ventricular hypertrophy (especially LVH)
Myocardial infarction (so called periinfarction blocks)
Drugs, especially class IA and IC antiarrhythmics (e.g., quinidine,
flecainide)
Hyperkalemia
Wolff-Parkinson-White Preexcitation
Although not a true IVCD, this condition causes widening of QRS complex
and, therefore, deserves to be considered here
QRS complex represents a fusion between two ventricular activation fronts:
Early ventricular activation in region of the accessory AV
pathway (Bundle of Kent)
Ventricular activation through the normal AV junction, bundle
branch system
ECG criteria include all of the following:
●
Short PR interval (