Right Bundle Branch Block

Dr. Muhammad Imran Janjua

HO- MU 1

The Heart

Anatomy Review

• Anatomy– SA Node– AV Node– Bundle of His– Left Bundle Branch

• Anterior fascicle

• Posterior fascicle

– Right Bundle Branch– Purkinje Fibres

Conducting System

Normal Ventricular Conduction

• Normal Conduction– fibers of LBB begin conduction

– impulse travels across inter ventricular septum from left to right

• towards + electrode creates small r wave

– travels across ventricles causing depolarization of both simultaneously

• LV contributes most to complex

– impulse travels away from + electrode creates primarily negative complex

Right bundle branch block (RBBB) results from a defect in the heart's electrical conduction system. There is a delay in or failure of transmission of electrical impulses down the right bundle of the heart. As a result, the

right ventricle depolarizes by means of cell-to-cell conduction. These impulses spread more slowly than usual from the inter ventricular septum to the right ventricle. This delay in conduction results in the characteristic

ECG pattern which is a wide and notched QRS. Although conduction down the right bundle is delayed, conduction down the left bundle is

normal. As result, the inter ventricular septum and left ventricle depolarize in the normal fashion

RBBB

RBBB

RBBB

• The incidence increases with age

1. Below age 30 the incidence is 1.3 per 1000

2. Between 30 and 44 it ranges from 2.0 to 2.9 per 1000

Differential Diagnosis of RBBB

• Acute pulmonary embolism

• Atrial septal defect

• Cardiomyopathy

• Cor Pulmonale

• Coronary Heart Disease

• Myocardial Infarction

• Myocarditis

• Rigt Bundle Branch Block

1.Complete RBBB

2.Incomplete RBBB

RBBB

Causes Of RBBB

1.After repair of the VSD

2.After right ventriculotomy

3.Right ventricular hypertrophy

4.Increase incidence of RBBB among population at high altitude

5.Ebstein’s anomaly

6.Large ASD (secundum type) or AV cushion defect

7.Brugada Syndrome

8.Trauma

Causes of Incomplete RBBB

1.Atrial septal defect (RAD in secundum or sinus venosus type, LAD with ostium primum type)

2.Ebstein’s anomaly3.Right ventricular dysplasia4.Congenital absence or atrophy of the bundle

branch5.After CABG and in transplanted hearts6.Brugada Syndrome

RBBB: Examination Findings

• Right bundle branch block is associated with a persistently split second heart sound with normal respiratory variation in the splitting interval.

RBBB: Lab Evaluation

• If there is a history of blunt trauma or any symptoms to suggest polymyositis then troponin, creatine kinase (CK) and an echocardiogram should be obtained.

Anatomic locations of RBBB

1. Proximal, or central, RBBB: block is located just distal to the bundle of His

2. Interruption between the proximal and distal aspects of the right bundle branch

3. Distal RBBB

RBBB

• The diagnostic criteria include:

• 1.QRS duration is >/- 120 ms

• 2.An rsr’,rsR’ or rSR’ pattern in lead V1 or V2 and occasionally a wide and notched R wave.

• 3.Reciprocal changes in V5,V6,I and AVL

RBBB Recognition

• Fundamental Criteria– Wide QRS

• > 100 ms (or, 0.10 sec)– Supraventricular rhythm

RBBB

• Criteria for incomplete RBBB are the same as for complete RBBB except that the QRS duration is < 120 ms

RBBB

• RBBB in V1– no change in initial impulse

travel• small r wave

– impulse depolarizes LV by itself since RBBB

– RV depolarized by impulse thru muscle

• it now contributes to complex

– travels toward + electrode creating positive deflection

R-S-R´

RBBB Recognition

RBBB Recognition Practice

RBBB ‘M’ pattern

RBBB

RBBB: Treatment

• In general treatment for right bundle branch block is not necessary.

• These patients need not limit their activity.

• If the RBBB progresses to heart block, further electrophysiologic testing may be necessary.

RBBB: Treatment

• Those patients who develop right bundle branch block after surgery should undergo EKG testing each year to evaluate for interval changes.

• Particular care should be taken to observe for the development of sinus bradycardia, supraventricular or ventricular ectopy.

RBBB

Thank You