Bundle Branch Block Determination II - Bundle Branch Block

Steps 1-3

Changes specifically seen include the QRS complex measuring 0.12 seconds or greater due to this delay. When determining the presence of BBB there are just a few simple steps to follow.

  • Step 1: Refer to lead V1
  • Step 2: Look for evidence that the electrical activity started above the ventricles (P wave). This is sometimes referred to as supraventricular activity.
  • Step 3: QRS complex measures 0.12 seconds or greater (not including aberrant complexes i.e. PVCs)

Steps 1-3 (continued)

By following the previous three steps, you will be able to determine whether a BBB is present or not.

Now it is simply a matter of one more step when analyzing the QRS in V1 to distinguish whether it is a left BBB or a right BBB.

Authors and Sources

Authors and Reviewers


? v:3 | onAr:0 | onPs:2 | tLb:3 | tLbJs:0
uStat: False | db:0 | shouldInvoke:False | pu:False | em:

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