Concealed conduction

[1] The term "concealed" is in reference to that the conduction is not observable by electrocardiogram.

[citation needed] Concealed conduction can be seen in cardiac aberrancy when a bundle branch temporarily blocks due to being refractory, and conduction from the other bundle branch conceals into the blocked branch retrograde thus perpetuation the bundle branch block morphology in subsequent beats.

For example, if a Premature atrial contraction reaches the right bundle branch while refractory the PAC will conduct with RBBB morphology.

Eventually, this will reach refractory conduction tissue and stop.

The subsequent beat — if early enough — will find the right bundle still refractory and the process will repeat yielding a continued RBBB morphology.