Right bundle branch block is a finding on electrocardiogram due to an interruption or alteration in the His-Purkinje system and is characterized by widened QRS complexes and changes in R and S wave vectors ^1,2. It can be complete or incomplete, with incomplete being the more common form of presentation and is generally seen in the absence of any cardiac disease ².  

Epidemiology

Right bundle branch block is more common in men than in women and is often found in the elderly. It affects 11.3% of people by 80 years of age ¹. RBBB is mostly seen in a normal heart without any disease. 

It is also associated with ¹: 

• hypertension 

• hyperkalemia 

• pulmonary embolism

• cor pulmonale

• Brugada syndrome

• structural cardiac disorders

Clinical presentation

The patient is usually asymptomatic or may have fainting spells. 

Diagnosis is made based on the ECG findings. 

QRS duration in V1 and V2 leads is more than 120 ms in complete RBBB and between 100-119 ms in incomplete RBBB ². 

Discordant ST segment is seen in both complete and incomplete RBBB. Inverted T waves are seen in right precordial leads and upright T waves are seen in left precordial leads ². 

When the RBBB ECG pattern is only seen with a raised heart rate, it is referred to as rate dependent RBBB ².

Pathology

When the right bundle branch has a block, the electrical impulse travels along the bundle of his to the left bundle branch causing the left ventricle to depolarize before the right ventricle ¹. The damage to the right bundle branch is mostly proximal and distal right bundle branch block is usually a consequence of trauma ¹.

Treatment and prognosis 

Treatment consists of managing the underlying conditions, if any are present. Patients who are asymptomatic usually do not require any treatment. The prognosis is generally good for patients without any cardiac condition ¹. 

In some cases, right bundle branch block may progress to complete heart block and result in sudden cardiac arrest ².