deck 6

Question 1

Patient has EKG w/ the following:

• NSR
• 2:1 AVB without PR-prolongation
• RBBB

What type of AV block should you code?

Answer 1

code for 2nd degree AVB, mobitz type II

2:1 AVB w/ evidence of His-Purkinje dz:

• mechanism is likely infranodal block
• Mobitz II should be coded

Question 2

Describe the strain pattern of RVH. (2)

Answer 2

The following are usually present in V1-V3 in RVH strain:

1. TWIs
2. +/- downsloping ST segment

Question 3

What is the incidence of progression to CHB in chronic bifascicular block?

Answer 3

10-15% (lifetime incidence)

Question 4

Pt becomes acutely hyperkalemic in the EP lab. His 12 lead EKG is shown below. EP study shows:

• functional sinus node
• 1:1 AV conduction

Explain the above findings.

Answer 4

• intact sinus node with sinoventricular conduction via specialized fibers → 1:1 AV conduction is preserved
• loss of p wave occurs due to complete failure of atrial conduction

Question 5

Young asthmatic with active wheezing has ischemic ST changes inferiorally. Biomarkers are negative.

Answer 5

think of hyperventilation-induced ST depressions

inferior ischemic ST in setting of respiratory distress:

• may occur in setting of hyperventilation
• does not always signify ischemia

Question 6

45M p/w reflux symptoms after eating an entire large pizza by himself. EKG shows ischemic ST changes inferiorally. LHC: clean coronaries.

Likely explanation for ekg changes?

Answer 6

• inferior ischemic EKG changes are likely due to electrical activity in stomach in this case
• GI-induced pseudo-ischemia classically occurs after a large carbohydrate meal)

Question 7

What are the 7 most common causes of artifact on an EKG?

Answer 7

1. AC interference (20 ms) - rapid and sinusoidal
2. Deep respirations - wandering baseline
3. Muscle Fasciculations (due to electrical activity in muscle)
4. Tremor - parkinson’s (300 ms), physiologic (500 ms),
5. Rapid arm motion (e.g. brushing teeth) - can simulate VT
6. cautery - pronounced baseline artifact
7. IV infusion pump - looks like rapid p waves

*cycle length is in parentheses

Question 8

What percentage of patients with the following potassium levels will have classic ST-U EKG changes?

• K = 3.0
• K < 2.7

Answer 8

• K = 3.0 → ~10% will have classic ST-U changes
• K < 2.7 → 80% will have classic ST-U changes