1.THEELECTROCARDIOGRAM Professor A. gowri shankar `s unit
Presentedby Dr. Ramesh unit -2
2. History
Mr . Ranganathan 60/male,
a known hypertensive 10yrs.
not a known DM / CAD.
no specific complaints.
3. CASE PRESENTATION 4.
Standardization and technical features are normal.
HR 94/min
Rhythm sinus.
P wave- normal
PR interval-(180 ms).
QRS DURATION- (0.13 s) .
mean QRS electrical axis (-70 to -60 ).
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
& aVF
QT interval-normal.
No abnormal Q waves / ST segment elevation
ECG interpretationName 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.
RBBB
Theimpulse is transmitted normally by left bundle to most of
left ventricle
Impulse to part of interventricular septum and RV
delayed,because of cellto cell depolarization
Slow impulse causes slower depolarization time.
LAFB
Depolarization of left ventricle has to progress from
interventricular septum, inferior wall, and posterior wall toward
anterior and lateral walls
Gives rise to unopposed vector pointed superior and
leftward
Changes net axis of ventricles toward left, producing left axis
deviation
Electrical axis of ventricles found in left quadrant of
hexaxial system, between 30 and 90.
7.
A typical RBBB ECG
wide QRS complexes with a terminal R wave in lead V1 &
slurred S wave in lead V6.
CRITERIAFOR RBBB CRITERIAFOR 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
Abnormalleft axis deviation( usually bt45 and 60)
qRcomplex in the lateral limb leads (I and aVL) &rSpattern
in the inferior leads (II, III, and aVF)
Delayedintrinsicoid deflectionin lead aVL (> 0.045 s)
left anterior fascicular block together with right bundle
branch block is indicative of ischaemia
8. 9. CausesofRBBBCauses 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 ECG
Slurred S wave in lead I & V 6.
rabbit ear pattern in V 1of RBBB w/delayed QRS complex of 0.12
sec or more
Left axis deviation & rS waves in lead III are typical of
LAFB
11. DISCUSSION
LAFB is far more common than LPFB why ?
The traditional explanations are
Anterior fascicle is relatively sub epicardial in location
It is a long and thin structure prone to damage easily
Exposed to the mechanical stress of LVOT
Anterior fascicle has only a single blood supply(LAD)
Clinical Significance of LAFB
seen in approximately4% 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.
