A right bundle branch block (RBBB) is a

heart block Heart block (HB) is a disorder in the heart's rhythm due to a fault in the natural pacemaker. This is caused by an obstruction – a block – in the electrical conduction system of the heart. Sometimes a disorder can be inherited. Despite the ...

in the right bundle branch of the electrical conduction system. During a right bundle branch block, the right ventricle is not directly activated by impulses traveling through the right bundle branch. However, the left bundle branch still normally activates the left ventricle. These impulses can then travel through the

myocardium Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall o ...

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 The bundle of His (BH) or His bundle (HB) ( "hiss"Medical Terminology for Health Professions, Spiral bound Version'. Cengage Learning; 2016. . pp. 129–.) is a collection of heart muscle cells specialized for electrical conduction. As part of ...

Purkinje fibres The Purkinje fibers, named for Jan Evangelista Purkyně, ( ; ; Purkinje tissue or subendocardial branches) are located in the inner ventricular walls of the heart, just beneath the endocardium in a space called the subendocardium. The Purki ...

, the

QRS complex The QRS complex is the combination of three of the graphical deflections seen on a typical electrocardiogram (ECG or EKG). It is usually the central and most visually obvious part of the tracing. It corresponds to the depolarization of the ri ...

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.

Incomplete right bundle branch block

An incomplete right bundle branch block (IRBBB) is a conduction abnormality in the right bundle branch block. While a complete RBBB has a QRS duration of 120 ms or more, an incomplete RBBB has a wave duration between 100 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%. It affects patients of all ages, more commonly males and athletes, however it is not always a benign finding. Therefore, if abnormalities are detected on the physical exam, further testing should be done to exclude heart disease. There is no consensus in the literature regarding criteria for diagnosis. However, according to the

American Heart Association The American Heart Association (AHA) is a nonprofit organization in the United States that funds cardiovascular medical research, educates consumers on healthy living and fosters appropriate Heart, cardiac care in an effort to reduce disability ...

American College of Cardiology Foundation The American College of Cardiology (ACC), based in Washington, D.C., is a nonprofit medical association established in 1949. It bestows credentials upon cardiovascular specialists who meet its qualifications. Education is a core component of the ...

Heart Rhythm Society The Heart Rhythm Society is an international non-profit organization that promotes education and advocacy for cardiac arrhythmia professionals and patients. The society was founded in 1979 and counted over 7,500 members from over 90 countries as o ...

(AHA/ACCF/HRS) it is defined by the following finding in adults: #QRS wave duration between 100 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.

Causes

Common causes include normal variation, changes in bundle branch structure - such as mechanical stretching, chest trauma,

right ventricular hypertrophy Right ventricular hypertrophy (RVH) is a condition defined by an abnormal enlargement of the cardiac muscle surrounding the right ventricle. The right ventricle is one of the four chambers of the heart. It is located towards the right lower chambe ...

or strain,

congenital heart disease A congenital heart defect (CHD), also known as a congenital heart anomaly, congenital cardiovascular malformation, and congenital heart disease, is a defect in the structure of the heart or great vessels that is present at birth. A congenital he ...

such as

atrial septal defect Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atrium (heart), atria (upper chambers) of the heart. Some flow is a normal condition both pre-birth and immediately post-birth via the Foramen ovale (heart) ...

, and

ischemic heart disease Coronary artery disease (CAD), also called coronary heart disease (CHD), or ischemic heart disease (IHD), is a type of heart disease involving the reduction of blood flow to the cardiac muscle due to a build-up of atheromatous plaque in the ...

. In addition, a right bundle branch block may also result from Brugada syndrome,

Chagas disease Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily Triatominae, known as "kissing bugs". The symptoms change throughout the ...

pulmonary embolism Pulmonary embolism (PE) is a blockage of an pulmonary artery, artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include dyspnea, shortness of breath, chest pain ...

rheumatic heart disease Valvular heart disease is any cardiovascular disease process involving one or more of the four valves of the heart (the aortic and mitral valves on the left side of heart and the pulmonic and tricuspid valves on the right side of heart). The ...

myocarditis Myocarditis is inflammation of the cardiac muscle. Myocarditis can progress to inflammatory cardiomyopathy when there is associated ventricular remodeling and cardiac dysfunction due to chronic inflammation. Symptoms can include shortness of bre ...

cardiomyopathy Cardiomyopathy is a group of primary diseases of the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...

, or

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

. Causes for incomplete right bundle branch block (IRBBB) often involve exercise-induced right

ventricular remodeling In cardiology, ventricular remodeling (or cardiac remodeling) refers to changes in the size, shape, structure, and function of the heart. This can happen as a result of exercise (physiological remodeling) or after injury to the heart muscle (patho ...

, increased right ventricular (RV) free wall thickness, especially in athletes due to prolonged endurance exercise.

Diagnosis

The criteria to diagnose a right bundle branch block on the electrocardiogram: * The heart rhythm must originate above the ventricles (i.e.,

sinoatrial node The sinoatrial node (also known as the sinuatrial node, SA node, sinus node or Keith–Flack node) is an ellipse, oval shaped region of special cardiac muscle in the upper back wall of the right atrium made up of Cell (biology), cells known as pa ...

atria Atria may refer to: Science *Atrium (heart) (plural: atria), an anatomical structure of the heart *Atria (genus), a flatworm genus in the family Dendrocoelidae * Atria (star) or Alpha Trianguli Australis, a star in the constellation Triangulum Aus ...

atrioventricular node The atrioventricular node (AV node, or Aschoff-Tawara node) electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the ...

) 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). * 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.

Treatment

The underlying condition may be treated by medications to control hypertension or diabetes, if they are the primary underlying cause. If

coronary arteries The coronary arteries are the arteries, arterial blood vessels of coronary circulation, which transport oxygenated blood to the Cardiac muscle, heart muscle. The heart requires a continuous supply of oxygen to function and survive, much like any ...

are blocked, an invasive coronary

angioplasty Angioplasty, also known as balloon angioplasty and percutaneous transluminal angioplasty, is a minimally invasive procedure, minimally invasive endovascular surgery, endovascular Medical procedure, procedure used to widen narrowed or obstructe ...

may relieve the impending RBBB.

Epidemiology

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.

Gallery

File:RBBB with first degree AV block.jpg, RBBB with associated first degree AV block File:Cardiogram indicating right bundle branch block with tachycardia.jpg, RBBB with associated tachycardia File:Cardiogram indicating right bundle branch block.jpg, RBBB

References

External links

{{Circulatory system pathology Cardiac arrhythmia fr:Bloc de branche#Bloc de branche droit