ecg: rbbb with lafb
TRANSCRIPT
- 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.
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- It can be seen withacute inferior wall MI .
12.