To provide some insight, bundle branch block occurs when the electrical impulse is not conducted down the one or more of the specialized conducting paths in the ventricles.
RBBB happens and may may occur due to degeneration with age, or may be due to specific pathology such as heart attack. The result of a block is electrical impulses pass slower through muscle than through the specialized conducting pathways. Contraction of the right ventricle is delayed.
There can be structual change affecting conduction in the right bundle due to right ventricular enlargement. There can be a sudden ventricular pressure that can deform pathways due to pulmonary hypertension due embolism (blood clot).
"Heart muscles not receiving a sufficient supply of oxygenated blood due vessel occlusions, heart attack, or inflammation of the heart muscles. Other causes include hypertension, cardiomyopathies, congenital heart disease, and mechanical damage, as may occur during right-sided cardiac catheterization or with the placing of a pacing catheter in the right ventricle. RBBB can also result from fibrosis of the skeleton of the heart; this disorder is called Lev's disease".
Individual with isolated chronic RBBB are generally asymptomatic and do not require a pacemaker. But if serious symptoms such as fainting, etc. occur, then a pacemaker.
If RBBB causes the right ventricle to increase, this enlargement can diminish the supply of blood to the lungs resulting in a reduced supply of blood to the left ventricle and then into circulation. This condition would be heart failure.
Hope this gives you an insight with RBBB. Thanks for the quesiton, and if you have any followup questions you are welcome to respond. Take care.