Download accelerated conduction

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: [email protected]
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.
ECG 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.
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.
WPW SYNDROME WITH
ATRIAL FIBRILLATION
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.
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.
ECG OF LGL Syndrome
Short P-R interval.
Normal QRS complex.
Normal T-wave.
No -wave.
LGL SYNDROME WITH
FIBRILLATION
ATRIAL
Short PR interval [less than 3 small squares].
No -wave.
REFERENCES
1. Das, Dr. P. C. – Textbook of Medicine [Reprint
April, 1995; Current Book International].
2. Ganong, Dr. William F. – Review of Medical
Physiology (22ND edition, 2005; McGraw Hill).
3. Mehta, Dr. P. J. – Understanding ECG [Reprint
6TH edition, 2008; The National Book Depot].
THANKS TO ALL ------