LEONARDO PASKAH SUCIADI, MDC A R D I O LO GY & VA S C U L A R M E D I C I N E - U N I V E R S I TA S PA D J A D J A R A N

B A N D U N G - I N D O N E S I A

PRE-EXCITATION SYNDROME

DEFINITION

Short PR interval + usually with abnormal QRS complex

Almost congenital pathologic processRelated to the presence of accessory

pathways in cardiac conduction systemClinically related to paroxysmal

tacchyarrhythmia events + symptomsCommonest known: Wolff-Parkinson-White

(WPW) syndrome and Lown-Ganong-Levine (LGL) syndrome

Normal Cardiac Conduction System

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, bothThe characteristics of AccP compared to AV nodal

conduction; FASTER conduction velocity LONGER refractory period (in sinus rhythm)

K = bundle of Kent; J = bundle of James; M = Mahaim fibres.The hatched area represents the atrioventricular border

Simplified representation of the various possible accessory conduction pathways

EPIDEMIOLOGY

WPW syndrome is the commonest (1.5/1000); LGL syndrome is rareMan > womanUsually with ‘healthy heart’; Multiple right sided AccP

are common in Ebstein’s anomalyThe 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)

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)

MECHANISM (in WPW syndrome)

Chou’s 6th ECG book

ECG CHANGES

WPW ECG pattern (Chou’s) 1. PR interval <0.12 s with a normal P wave2. QRS complex >0.11 s3. 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

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 V2Type 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

Type A or B ?

Type A or B ?

LGL ECG pattern

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

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