ECG: RBBB with LAFB

1. THE THE
ELECTROCARDIOGRAMELECTROCARDIOGRAM
Professor A. gowri shankar `s unit
Presented by
Dr. Ramesh
unit -2

2. History History
Mr . Ranganathan 60/male, Mr . Ranganathan 60/male,
a known hypertensive – 10yrs. a known hypertensive – 10yrs.
not a known DM / CAD.not a known DM / CAD.
no specific complaints.no specific complaints.

3. CASE PRESENTATION CASE PRESENTATION

4. Standardization and technical features are normal.Standardization and technical features are normal.
HR – 94/minHR – 94/min
Rhythm – sinus.Rhythm – sinus.
P wave- normalP wave- normal
PR interval -(180 ms).PR interval -(180 ms).
QRS DURATION- (0.13 s) .QRS DURATION- (0.13 s) .
mean QRS electrical axis (-70 to -60mean QRS electrical axis (-70 to -60´´).).
QRS configuration – rSR pattern in lead V1 & slurring of S wave in V6.QRS configuration – rSR pattern in lead V1 & slurring of S wave in V6.
qR pattern in lead 1 & aVL, `r S`pattern in lead II, III & aVFqR pattern in lead 1 & aVL, `r S`pattern in lead II, III & aVF
QT interval-normal.QT interval-normal.
No abnormal Q waves / ST segment elevationNo abnormal Q waves / ST segment elevation
ECG interpretation
Name – Mr. Ranganathan, 60/m.
Date - 19/6/11

5. The Electrical System of the Heart
AV Node
Posterior Inferior Fascicle
Anterior Superior Fascicle
Septal Depolarization
Fibers
Purkinjie Fibers
Inter- nodal Tracts
Bundle of HIS
Left Bundle
Branch
Right Bundle
Branch
SA Node

6. RBBBRBBB
The impulse is transmitted The impulse is transmitted
normally by left bundle to normally by left bundle to
most of left ventricle most of left ventricle
Impulse to part of Impulse to part of
interventricular septum and interventricular septum and
RV delayed, because of cell RV delayed, because of cell
to cell depolarization to cell depolarization
Slow impulse causes slower Slow impulse causes slower
depolarization time.depolarization time.
LAFBLAFB
Depolarization of left Depolarization of left
ventricle has to progress ventricle has to progress
from interventricular from interventricular
septum, inferior wall, and septum, inferior wall, and
posterior wall toward posterior wall toward
anterior and lateral walls anterior and lateral walls
Gives rise to unopposed Gives rise to unopposed
vector pointed superior and vector pointed superior and
leftward leftward
Changes net axis of Changes net axis of
ventricles toward left, ventricles toward left,
producing left axis deviationproducing left axis deviation
Electrical axis of ventricles Electrical axis of ventricles
found in left quadrant of found in left quadrant of
hexaxial system, between –hexaxial system, between –
30˚ and –90˚.30˚ and –90˚.

7. CRITERIA FOR RBBB CRITERIA FOR LAFB
The heart rhythm must originate above the
ventricles (i.e. SA node, AVnode) to activate the
conduction system at the correct point.
The QRS duration >100 ms (incomplete block)
or >120 ms (complete block)
[3]
 terminal R wave in lead V1 (e.g. R, rR', rsR',
rSR' or qR)
slurred S wave in leads I and V6
Abnormal left axis deviation (usually bt –
45° and –60°)
qR complex in the lateral limb leads (I and
aVL) & rS pattern in the inferior leads (II, III,
and aVF)
Delayed intrinsicoid deflection in lead aVL
(> 0.045 s)
left anterior fascicular block together with
right bundle branch block is indicative of
ischaemia
A typical RBBB A typical RBBB
ECGECG
wide QRS wide QRS
complexes with a complexes with a
terminal R wave in terminal R wave in
lead V1 &lead V1 &
 slurred S wave in slurred S wave in
lead V6.lead V6.

9. Causes of RBBB Causes of LAFB
•Normal variant.
•Cor pulmunale.
•Pulmonary embolism.
•MI, CMP`S, HHD,CHD
•Mechanical damage.
•Lev`s disease.
•Chronic hypertension
•Aortic stenosis
•Aortic root dilation
•Dilated cardiomyopathy
•Impairment of the cardiac electrical
conduction system
•Acute myocardial infarction
•Lung diseases
•Aging
•Degenerative fibrotic disease

10. Combination of RBBB & LAFH on Combination of RBBB & LAFH on
ECGECG
Slurred S wave in lead I & VSlurred S wave in lead I & V
6.6.
rabbit ear pattern in Vrabbit ear pattern in V
11 of RBBB w/delayed of RBBB w/delayed
QRS complex of 0.12 sec or more QRS complex of 0.12 sec or more
Left axis deviation & rS waves in lead III are Left axis deviation & rS waves in lead III are
typical of LAFBtypical of LAFB

11. DISCUSSIONDISCUSSION
LAFB is far more common than LPFB why ?LAFB is far more common than LPFB why ?
The traditional explanations are The traditional explanations are
•Anterior fascicle is relatively sub epicardial in locationAnterior fascicle is relatively sub epicardial in location
•It is a long and thin structure prone to damage easilyIt is a long and thin structure prone to damage easily
•Exposed to the mechanical stress of LVOT Exposed to the mechanical stress of LVOT
•Anterior fascicle has only a single blood supply(LAD)Anterior fascicle has only a single blood supply(LAD)
Clinical Significance of LAFB

•seen in approximately 4% of acute MI
•It is the most common type of intraventricular
conduction defect seen in acute anterior MI, and the left
anterior descending artery is usually the culprit vessel.
•It can be seen with acute inferior wall MI.