A right bundle branch block (RBBB) is a heart block in the right bundle branch of the electrical conduction system.[1] Show
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. 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:
The first three criteria are needed for diagnosis. The fourth is needed when a pure dominant R waver is present on V1.[3] 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] Diagnosis[edit]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). The criteria to diagnose a right bundle branch block on the electrocardiogram:
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] 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] 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] Gallery[edit]
See also[edit]
References[edit]
External links[edit]How do you differentiate between incomplete and complete RBBB?You can distinguish between Left Bundle Branch Block and Right Bundle Branch Block simply by looking at the QRS morphology in V1 and V6.. If the QRS looks like W in V1 and M in V6 it is LBBB. ( WiLLiam). If the QRS looks like M in V1 and W in V6 it is RBBB. ( MoRRow). What does it mean to have an incomplete right bundle branch block?Right bundle branch block is a problem with your right bundle branch that keeps your heart's electrical signal from moving at the same time as the left bundle branch. Instead of moving together on the left and right sides, the signal on the right side is running behind. This creates an irregular heartbeat.
Should I worry about incomplete right bundle branch block?You may not need any treatment at all for right bundle branch block. People without any symptoms do, however, need careful evaluation at the time of diagnosis. In people with known or suspected heart disease, right bundle branch block is associated with a greater risk of death, especially after a heart attack.
Is incomplete right bundle branch block normal?Incomplete RBBB is thus regarded as a benign condition but—to our knowledge—this is based on only one study of 134 asymptomatic middle-aged men which reported no increased risk of death due to coronary heart disease (CHD) or cardiovascular diseases (CVDs) in 20 years of follow-up.
|