An overview of bundle branch block (BBB) is provided in a separate article, which includes a discussion of what BBB is, what causes it, and how it affects the ECG. This present article will discuss RBBB in particular, especially its clinical significance and what it means to have RBBB.
RBBB normally doesn't affect young, healthy people, However, the frequency of RBBB increases with age. By age 80, more than 11% of people will develop RBBB.
If you have RBBB, the most important thing to know is that it can indicate the presence of an underlying heart or lung condition. If a thorough evaluation reveals no such medical condition, then your RBBB very probably benign (not harmful).
RBBB and Underlying Heart and Lung DiseaseRBBB is somewhat more common than left bundle branch block (LBBB). This is because the right bundle branch, as it courses within the muscle of the right ventricle, is relatively superficial (that is, near the surface of the ventricular cavity) for much of its length. This makes it susceptible to damage and stretching whenever the right ventricle is placed under stress of any kind. RBBB often occurs in any condition that affects the right ventricle. These conditions can include coronary artery disease (CAD), myocarditis (inflammation of the cardiac muscle), atrial septal defect, ventricular septal defect, and valvular heart disease. RBBB may also be a result of any lung condition that causes a chronic elevation in the pressures of the right ventricle - typically, this is seen in some types of chronic obstructive pulmonary disease (COPD). Furthermore, RBBB is common with any condition that acutely raises pressures in the right ventricle. The most common condition that does this is pulmonary embolus.
What this means is that if you are discovered to have RBBB, your doctor should take a careful medical history and perform a full physical examination (concentrating on signs of heart and lung disease), and usually should also order an echocardiogram to look for unapparent heart disease.
Because the right bundle branch is somewhat susceptible to anything that can produce even small trauma in the right ventricle, transient RBBB occurs in approximately 5% of patients undergoing cardiac catheterization. This temporary RBBB occurs when the catheter irritates the right bundle branch. The RBBB usually resolves quickly when the catheter is removed. However, in patients who have LBBB, causing temporary RBBB like this will create complete heart block - and the heart can stop beating. So in patients who have LBBB and who are having a cardiac catheterization study, sometimes a temporary pacemaker is inserted during the procedure, to assure that the heart rhythm will continue uninterrupted during the study.
RBBB and the Efficiency of the HeartbeatIn any type of BBB, the heart's two ventricles are being stimulated in sequence (one after the other) instead of simultaneously. This loss of normal coordination between the two ventricles can reduce the efficiency of the heart beat. However, the reduction in the heart's efficiency is far less pronounced in RBBB than it is in LBBB, and many experts believe that RBBB causes no loss of efficiency at all.
Because BBB is associated with a loss of cardiac efficiency, it is currently recommended that many patients who have heart failure and a reduced left ventricular ejection fraction, in addition to bundle branch block, should receive cardiac resynchronization therapy (CRT). (CRT is a type of pacemaker that re-coordinates the contraction of the ventricles to improve cardiac efficiency.) But while CRT can produce a significant improvement in cardiac function in heart failure patients with LBBB, the evidence that CRT helps very much with RBBB is quite sparse.
SummaryRBBB is itself a benign condition that requires no treatment. However, if you are found to have RBBB, you should talk with your doctor about performing a screening evaluation for underlying heart or lung disease. If none is found, then your RBBB can be written off as an incidental finding with no medical significance.
Eriksson P, Wilhelmsen L, Rosengren A. Bundle-branch block in middle-aged men: risk of complications and death over 28 years. The Primary Prevention Study in Göteborg, Sweden. Eur Heart J 2005; 26:2300.
Barsheshet A, Goldenberg I, Garty M, et al. Relation of bundle branch block to long-term (four-year) mortality in hospitalized patients with systolic heart failure. Am J Cardiol 2011; 107:540.