3
• Pre-excitation
pattern
An ECG pattern reflecting the presence of a manifest accessory
pathway connecting the atrium to the ventricle. Pre-excited
ventricular activation over the accessory pathway competes
with the anterograde conduction over the AV node and spreads
from the accessory pathway insertion point in the ventricular
myocardium. Depending on the relative contribution from
ventricular activation by the normal AV nodal / His Purkinje
system versus the manifest accessory pathway, a variable
degree of pre-excitation, with its characteristic pattern of a
short P-R interval with slurring of the initial upstroke of the
QRS complex (delta wave), is observed. Pre-excitation can
be intermittent or not easily appreciated for some pathways
capable of anterograde conduction; this is usually associated
with a low-risk pathway, but exceptions occur.
• Asymptomatic pre-
excitation (isolated
pre-excitation)
e abnormal pre-excitation ECG pattern in the absence of
documented SVT or symptoms consistent with SVT.
• Wolff-Parkinson-
White (WPW)
syndrome
Syndrome characterized by documented SVT or symptoms
consistent with SVT in a patient with ventricular pre-excitation
during sinus rhythm.
Atrioventricular
reentrant
tachycardia (AVRT)
A reentrant tachycardia, the electrical pathway of which
requires an accessory pathway, the atrium, AV node (or second
accessory pathway), and ventricle.
• Orthodromic
AVRT
An AVRT in which the reentrant impulse uses the accessory
pathway in the retrograde direction from the ventricle to the
atrium, and the AV node in the anterograde direction. e QRS
complex is generally narrow or may be wide because of pre-
existing bundle-branch block or aberrant conduction.
• Antidromic AVRT An AVRT in which the reentrant impulse uses the accessory
pathway in the anterograde direction from the atrium to
the ventricle, and the AV node for the retrograde direction.
Occasionally, instead of the AV node, another accessory
pathway can be used in the retrograde direction, which is
referred to as pre-excited AVRT. e QRS complex is wide
(maximally pre-excited).
Permanent form
of junctional
reciprocating
tachycardia (PJRT)
A rare form of nearly incessant orthodromic AVRT involving
a slowly conducting, concealed, usually posteroseptal accessory
pathway.
Pre-excited AF AF with ventricular pre-excitation caused by conduction over
≥1 accessory pathway(s).
Table 1. Relevant Terms and Definitions (cont'd)
Arrhythmia/Term Definition
