Hemiblocks

Question 1

What exactly is a hemiblock?

Answer 1

It is a blockage of the impulse running through the left bundle branch, either the anterior or posterior division.

Question 2

What is the most common cause of a hemiblock?

Answer 2

Loss of blood supply to the divisions

Question 3

Which of the two hemiblocks are more common?

Answer 3

Left anterior hemiblock.

Question 4

What does the RCA supply relevant to electrical impulses?

Answer 4

SA node, AV node, bundle of HIS, and part of the posterior division of the left bundle branch.

Question 5

Same question for LCA?

Answer 5

Part of the posterior division, Right bundle branch and anterior division of left bundle branch.

Question 6

4 criteria to diagnose a left anterior hemiblock?

Answer 6

1. LAD
2. Normal or slightly widened QRS
3. Q1S3 - small Q in 1 and a wide/deep S in lead 3.
4. Small R in 2,3,F

Question 7

Most common cause of LAH?

Answer 7

LAD occlusion - MI

Question 8

What else can be present with a LAH and why?

Answer 8

RBBB because the LCA is also supplying the right bundle branch

Question 9

What is usually the cause of a posterior hemiblock?

Answer 9

Inferior infarction

Question 10

3 criteria for posterior hemiblock?

Answer 10

RAD, normal or slightly widened QRS, S1Q3 (wide S in 1 and a small q in 3)

Question 11

When a patient shifts from normal axis to abnormal axis, wat are we thinking is going on?

Answer 11

Hemiblock

Question 12

What are we meaning when we say fascicular block?

Answer 12

Bundle branch block plus a hemiblock

Question 13

What do we mean when we say bifascicular block?

Answer 13

Usually a RBBB with either an anterior or posterior block of the left bundle branch