Ventricular pre-excitation occurs when a part of the ventricular myocardium is activated by an impulse originating in the atrium which arrives via an accessory atrioventricular pathway before the impulse transmitted via the normal cardiac conduction system. The Wolff-Parkinson-White Syndrome is associated with ventricular pre-excitation. If the accessory pathway can be identified, then it can be ablated. The algorithm of Milstein et al uses a 12 lead electrocardiogram to localize the accessory pathway to one of 4 anatomic regions.
Features of the Wolff-Parkinson-White Syndrome:
(1) PR interval < 0.12 seconds
(2) delta wave at the beginning of the QRS complex
(3) rapid, regular tachyarrhythmia
Anatomic regions identified by algorithm:
(1) left free wall
(2) posteroseptal
(3) anteroseptal
(4) right free wall
Decision points (DP) for the algorithm to localize the accessory pathway:
(1) Q wave or isoelectric delta wave in L1, aVL or V6
(2) criteria for LBBB present (below)
(3) Q wave or isoelectric delta wave in at least two of the following: L2, L3, aVF
(4) Rs or RS present in V1, V2, or V3
(5) Rs or RS present in V1 or V2
(6) QRS axis > +30°
Criteria for left bundle branch block (LBBB):
(1) positive QRS in lead 1
(2) QRS with a duration >= 0.09 seconds (90 ms)
(3) rS complexes in leads V1 and V2
|
location of accessory pathway |
DP1 |
DP2 |
DP3 |
DP4 |
DP5 |
DP6 |
|
right anteroseptal (1) |
Y |
Y |
|
|
|
|
|
right anteroseptal (2) |
N |
Y |
N |
|
|
Y |
|
left lateral free wall (1) |
Y |
N |
|
|
|
|
|
left lateral free wall (2) |
N |
N |
N |
|
Y |
|
|
posteroseptal |
N |
|
Y |
Y |
|
|
|
right lateral free wall (1) |
N |
|
Y |
N |
|
|
|
right lateral free wall (2) |
N |
Y |
N |
|
|
N |
|
undetermined |
N |
N |
N |
|
N |
|
Performance of algorithm:
• In 141 patients, about 90% of the accessory pathways were correctly identified.
• Difficulties occur with multiple pathways, ventricular hypertrophy, superimposed myocardial infarction or if the pre-excitation is minor.
Specialty: Cardiology
ICD-10: ,
