Little significance – may progress to advanced heart block – but this is very rare.

Pulmonary artery catheter (PAC) – Special attention should be given to patients with a planned insertion of a pulmonary artery catheter (PAC). The insertion may cause a right bundle branch block (RBBB), which happens in 2-5% of PAC insertions. In combination with a preexisting left bundle branch block (LBBB), a RBBB can lead to a complete heart block (3rd degree heart block).

Pacing – Know where you can find pacing equipment if complete heart block occurs. There’s no evidence that anesthetic-induced changes in the body would progress a bifascicular block to a third-degree heart block, so prophylactically placing a cardiac pacemaker is NOT indicated.

Caused by a blockade of the cardiac electrical impulse as it moves over the right bundle branch.

This condition is common, existing in approximately 1% of patients. Without accompanying structural heart disease, this condition often has no clinical significance in patients without structural heart disease.

This condition is recognized in leads V1 and V2 as a widened QRS (> 120 ms) complex, rSR complex in leads V1 and V2, and a significant S wave (>40 ms) in leads I and V6.

Incomplete RBBB – When all other criteria are met except the QRS is only slightly prolonged (110-120 ms).

Two heart blocks to know when considering a RBBB severity/risk:
Left Anterior Fascicular Block (LAFB), which is also known as a Left Anterior Hemiblock (LAHB)
Left Posterior Fascicular Block (LPFB), which is also known as a Left Posterior Hemiblock (LPHB)

Bifascicular heart block (When a RBBB is combined with a LAFB or LPFB)
RBBB + LAFB or LAHB = very little/no significance
RBBB + LPFB or LPHB = This may progress to third-degree heart block (1-2% of patients with this combination each year)