1) A right bundle branch block is a heart block in the right bundle branch of the electrical conduction system that causes the right ventricle to be activated slower than the left ventricle. 2) It is diagnosed on an electrocardiogram by a widened QRS complex over 120ms with a terminal R wave in lead V1 and prolonged S wave in lead V6. 3) Causes include mechanical stretching of the bundle branch, heart conditions like right ventricular hypertrophy, and underlying diseases like hypertension. Treatment focuses on managing the underlying condition.

1. RIGHT BUNDLE BRANCH
BLOCK

2. Right bundle branch block
An illustration of a right bundle branch block located in intraventricular septum
ECG characteristics of a typical RBBB showing wide QRS complexes with a terminal R wave in lead V1 and a prolonged S wave in lead V6.
Specialty Cardiology
Types complete right bundle branch block (CRBBB)
incomplete right bundle branch block (IRBBB)

3. • A right bundle branch block (RBBB) is a heart block in the right bundle branch of the electrical
conduction system.[1]
• During a right bundle branch block, the right ventricle is not directly activated by impulses travelling
through the right bundle branch. The left ventricle, however, is still normally activated by the left
bundle branch. These impulses are then able to travel through the myocardium of the left ventricle to
the right ventricle and depolarize the right ventricle this way. As conduction through the myocardium is
slower than conduction through the Bundle of His-Purkinje fibres, the QRS complex is seen to be
widened. The QRS complex often shows an extra deflection that reflects the rapid depolarisation of
the left ventricle followed by the slower depolarisation of the right ventricle.

4. • Incomplete right bundle branch block[edit]
• Incomplete right bundle branch block (IRBBB) is an conduction abnormality in the right bundle branch
block. While a complete RBBB has a QRS duration of 120 ms or more, an incomplete block has a wave
duration between 110 and 120 ms. It has a relatively high prevalence, a study conducted on young Swiss
military conscripts with a mean age of 19 years found a prevalence of 13.5%.[2] It affects patients of all
ages, more commonly males and athletes, however is not always a benign finding. Therefore, if
abnormalities are detected on the physical exam, further testing should be done to exclude heart disease.[3]
• There is no consensus in the literature regarding criteria for diagnosis. However, according to the
American Heart Association/American College of Cardiology Foundation/Heart Rhythm Foundation
(AHA/ACCF/HRS) it is defined by the following finding in adults:
• QRS wave duration between 110 and 120 ms.
• rsr, rsR, or rSR in leads V1 or V2.
• S wave of longer duration than R wave or greater than 40 ms in leads I and V6.
• Normal R wave peak time in both V5 and V6, but greater than 50 ms in V1.
• The first three criteria are needed for diagnosis. The fourth is needed when a pure dominant R waver is
present on V1.[3]

5. • Causes[edit]
• Common causes include: normal variation, changes in bundle branch structure - such as
mechanical stretching, chest trauma, right ventricular hypertrophy or strain, congenital heart
disease such as atrial septal defect, and ischemic heart disease. [4] In addition, a right bundle branch
block may also result from Brugada syndrome, pulmonary embolism, rheumatic heart
disease, myocarditis, cardiomyopathy, or hypertension.[citation needed]
• Causes for incomplete right bundle branch block are exercise-induced right ventricular remodeling,
increased RV free wall thickness, especially in athletes due to prolonged endurance exercise.[5]

6. Diagnosis[edit]
Normal electrical conduction system of the heart (Schematic). All myocardial segments are excited almost simultaneously (purple staining).
•Sinoatrial node
•Atrioventricular node
Conduction in RBBB (Schematic): With a blockage in the right bundle branch (red), the left ventricle is excited in time (purple), while the excitation of the right ventricle takes a detour via the left bundle branch (blue arrows).

7. • The criteria to diagnose a right bundle branch block on the electrocardiogram:
 The heart rhythm must originate above the ventricles (i.e., sinoatrial node, atria or atrioventricular
node) to activate the conduction system at the correct point.
 The QRS duration must be more than 100 ms (incomplete block) or more than 120 ms (complete
block).[6]
 There should be a terminal R wave in lead V1 (often called "R prime," and denoted by R, rR', rsR',
rSR', or qR).
 There must be a prolonged S wave in leads I and V6 (sometimes referred to as a "slurred" S
wave).
• The T wave should be deflected opposite the terminal deflection of the QRS complex. This is known
as appropriate T wave discordance with bundle branch block. A concordant T wave may suggest
ischemia or myocardial infarction.[citation needed]

8. • Treatment[edit]
• The underlying condition may be treated by medications to control hypertension or diabetes, if they
are the primary underlying cause. If coronary arteries are blocked, an invasive
coronary angioplasty may relieve the impending RBBB.[7]

9. • Epidemiology[edit]
• Prevalence of RBBB increases with age due to changes in the heart's conduction system. It's
estimated up to 11.3% of the population by the age of 80 have RBBB.[8]