3INTRODUCTIONThere are 02 types of accelerated conductions from the atrium to the ventricles; viz.Wolff-Parkinson-White (WPW) Syndrome / Pre-excitation Syndrome.Lown-Ganong-Levine (LGL) Syndrome.
4WPW SYNDROMEBundle of Kent by-pass the AV node or by Mahaim fibes – which goes from Bundle of His to Ventricular Septum. The pre-excitation of ‘Bundle of Kent’ is called WPW Syndrome.The atrial impulse passes through the normal path of conduction and also through the anterior intra-nodal fibre [Bachmann’s fibre / Bundle of Kent], simultaneously.
5CLASSIFICATION OF WPW SYNDROME WPW Syndrome is of 02 types ----Type A: where excitation travels along Left accessory pathway – giving rise to RVH / RBBB.Type B: where excitation travels along Right lateral accessory pathways – giving rise to LBBB. If it is associated with Cyanotic CHD – Ebstein’s Anomaly is diagnosed.
6ECG OF WPW Syndrome Short P-R interval [less than 0.12 sec.]. Wide QRS complex.Appearance of -wave / slurred upstroke of QRS.Normal P-wave axis.
7CAUSES OF WPW Syndrome Normal individuals. Myocardial Infarction. Acute Rheumatic Fever.CHD – Ebstein’s Anomaly.Cardiac catheterization / Surgical manipulation of Heart.Hypertrophic Sub-aortic Stenosis.Idiopathic Cardiomyopathy.Thyrotoxicosis.
8WPW SYNDROME WITH ATRIAL FIBRILLATION Irregularly irregular, wide complex tachycardia.Impulses from the atria are conducted to the ventricles via eitherboth the AV node and Accessory pathway producing a broad fusion complex.or just AV node producing a narrow complex (without -wave).or just Accessory pathway producing a very broad 'pure' - wave.People who develop this rhythm and have very short R-R intervals are at higher risk of VF.
9LGL SyndromeJames Accesory Tract / Bundle of James by-pass the upper part of the AV node. The pre-excitation of the ‘Bundle of James’ is called LGL Syndrome.The artrial impulse preferentially passes through the posterior intra-nodal fibre [Thorel’s fibre / Bundle of James] and conducted to His Bundle.Pateints of this syndrome are prone to develop Supra-ventricular arrhythmias, ventricular tachycardia & Ventricular fibrillation.
10ECG OF LGL Syndrome Short P-R interval. Normal QRS complex. Normal T-wave.No -wave.
11LGL SYNDROME WITH ATRIAL FIBRILLATION Short PR interval [less than 3 small squares].No -wave.
12REFERENCESDas, Dr. P. C. – Textbook of Medicine [Reprint April, 1995; Current Book International].Ganong, Dr. William F. – Review of Medical Physiology (22ND edition, 2005; McGraw Hill).Mehta, Dr. P. J. – Understanding ECG [Reprint 6TH edition, 2008; The National Book Depot].