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ECG: UNDERSTANDING ACCELERATED CONDUCTION. Dr. Krishnendu Maity BHMS [Calcutta] MD (Hom. Repertory) [Pune] Professor & HOD, Dept. of Medicine Teaching Medicine, Materia & Repertory Lal Bahadur Shastri Homœopathic Medical College, Bhopal – 26 (MP) Email : post.krishnendu2010@ymail.com.
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ECG: UNDERSTANDING ACCELERATED CONDUCTION Dr. Krishnendu Maity BHMS [Calcutta] MD (Hom. Repertory) [Pune] Professor & HOD, Dept. of Medicine Teaching Medicine, Materia & Repertory Lal Bahadur Shastri Homœopathic Medical College, Bhopal – 26 (MP) Email: post.krishnendu2010@ymail.com
INTRODUCTION There 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.
WPW SYNDROME • Bundle 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.
CLASSIFICATION 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.
Short P-R interval [less than 0.12 sec.]. Wide QRS complex. Appearance of -wave / slurred upstroke of QRS. Normal P-wave axis. ECG OF WPW Syndrome
CAUSES 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.
Irregularly irregular, wide complex tachycardia. Impulses from the atria are conducted to the ventricles via either both 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. WPW SYNDROME WITH ATRIAL FIBRILLATION
LGL Syndrome • James 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.
Short P-R interval. Normal QRS complex. Normal T-wave. No -wave. ECG OF LGL Syndrome
Short PR interval [less than 3 small squares]. No -wave. LGL SYNDROME WITH ATRIAL FIBRILLATION
REFERENCES • Das, 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].
