knowing a basic concept of pre-excitation syndrome, and how to detect it based on ECG

1. PRE-EXCITATION
SYNDROME
LEONARDO PASKAH SUCIADI , MD
CARDIOLOGY & VASCULAR MEDICINE -UNI VERSI TAS
PADJADJARAN
BANDUNG- INDONESIA

2. DEFINITION
Short PR interval + usually with abnormal QRS
complex
Almost congenital pathologic process
Related to the presence of accessory pathways in
cardiac conduction system
Clinically related to paroxysmal tacchyarrhythmia
events + symptoms
Commonest known: Wolff-Parkinson-White (WPW)
syndrome and Lown-Ganong-Levine (LGL)
syndrome

3. Normal Cardiac Conduction System

4. ACCESSORY PATHWAYS (AccP)
AccP is congenitally abnormal pathway connecting
A-V
Varies in :
 connecting circuits: atrioventricular (Kent’s bundle); Mahaim
fibers (atriofascicular/Brecenmacher tract, nodoventricular,
fasciculoventricular); atriohisian (James’s fiber)
 direction: anterograde, retrogade, both
The characteristics of AccP compared to AV nodal
conduction;
 FASTER conduction velocity
 LONGER refractory period (in sinus rhythm)

6. Simplified representation of the various possible
accessory conduction pathways
K = bundle of Kent; J = bundle of James; M = Mahaim fibres.
The hatched area represents the atrioventricular border

7. EPIDEMIOLOGY
WPW syndrome is the commonest (1.5/1000);
LGL syndrome is rare
Man > woman
Usually with ‘healthy heart’; Multiple right sided AccP
are common in Ebstein’s anomaly
The commonest presenting symptoms are related to
tacchyarrhythmia events (palpitation, presyncope,
syncope, chest discomfort, dyspnea)
The commonest type of tacchyarrhythmias= AVRT
(80%)  frequency of PSVT is increased with age
(10/100 in 20-40 yo VS 36/100 in >60 yo)
In patients with history of recurrent tacchyarrhythmia,
prognosis is still good; SCD is only 0.1% (rare)

8. Atrio-Ventricular Re-entry Tacchycardia (AVRT)
AccP is the component of a closed circuit = macro-reentry
Rapid tacchycardia with ventricular beats 150-250
bpm (faster than AVNRT); can be with narrow or
widened complex QRS
Based on pathophysiology and ECG changes 
Orthodromic and antidromic AVRT
Sudden in onset and termination (paroxysmal)

9. MECHANISM (in WPW syndrome)
Chou’s 6th ECG book

11. ECG CHANGES
WPW ECG pattern (Chou’s)
1. PR interval <0.12 s with a normal P wave
2. QRS complex >0.11 s
3. initial slurring of the QRS complex (delta wave)
4. secondary ST segmen and T wave changes
LGL ECG pattern  shortened PR interval without
abN width or form of QRS complex

14. WPW ECG Type
(Harold L.Brook’s ECG book)
Type A (more common) Kent’s fiber to LV
criteria; WPW patterns with tall R waves in leads V1
and V2
Type B (much less common; more common in
Ebstein’s anomaly)  Kent’s fiber to RV
criteria; WPW patterns with predominantly negative
R waves and delta waves in V1 and V2, or deep QS
waves in V1 and V2  anteroseptal pseudoinfarct

16. Type A or B ?

17. Type A or B ?

18. LGL ECG pattern

19. MANAGEMENT
Asymptomatic patients  no further FU or th/
Th/ :
 Cathetherization RFA  definite th/
 Pharmacologic agents: decreasing conduction time and/or prolonging
refractory period to AV node and/or AccP
 recommendation; agents IA, IC, III. Verapamil is also considerable
 symptoms control
During paroxysmal AVRT  according ACLS
(haemodynamically stable/instable? Narrow/wide QRS
complex)
Precaution in AVRT;
 Digitalis, verapamil IV, cathecolamines  reduce refractory period of
AccP  in Afib, these agents could lead to VF
 In pts with SVT, it is wise to carry out ECG recording after rhythm
conversion to recognize any preexisting pre-excitation pattern

20. THANK YOU