EKG Basics Part 2

Question 1

Besides lead I and aVF, what lead do we need to precisely determine axis?

Answer 1

Isoelectric lead, which will be biphasic because it is half positive and half negative.

Question 2

What segment of an EKG is generally most definitive of baseline?

Answer 2

T wave to the next P wave.

T-P Segment is best to determine baseline.

Question 3

What is atrial hypertrophy usually referred to as on EKG?

Answer 3

Atrial enlargement

Its not really muscular or thicker.

Not an increase in myocytes. Generally affects shape and timing of P wave, rather than the amplitude.

Question 4

What is the duration and amplitude of a normal P wave?

Answer 4

< 0.12 s and < 2.5 mm

Less than 3 small boxes wide and 2.5 small boxes tall.

Question 5

What is the criteria for RAE?

Answer 5

P wave > 2.5mm in an inferior lead.
RA corresponds to the first half of a P-wave as well.

Inferior: II, III, aVF

Abnormal shows 3 mm for P wave in Lead II.
V1 generally corresponds as well.

Question 6

What is the criteria for LAE?

Answer 6

• P wave > 0.12s w/ terminal portion > 0.04s
• Terminal portion of P wave in V1 > 1 mm below.

P wave elongation + extended end-phase.
P wave is highly negative.
Criteria refers to Lead II and VI.

Question 7

What is the criteria for RVH?

Answer 7

• R axis deviation
• Negative QRS in left leads (I, aVL)
• V1 will have R wave > S wave
• V6 will have S wave > R wave

Just has to generally meet most criteria.

Chest leads: generally show inverted R wave progression. (aka no R wave progression)

Question 8

What is criteria for LVH?

Answer 8

• R-wave amplitude in aVL exceeds 11mm.
• R-wave amplitude in either V5 or V6 + S wave in either V1 or V2 exceeds 35mm.

You can use either criteria to qualify for LVH.

R wave in V5 or V6 is generally the largest.
S wave in V1 or V2 is generally the largest.

Question 9

Not on exam but FYI

Combined LVH criteria

Answer 9

R-wave amplitude in aVL + S wave in V3 > 20 in women and 28 in men.

Question 10

In what patients is ventricular hypertrophy not applicable to?

Answer 10

Patients < 35 yo

Athletes generally meet criteria, but on echo, it will almost never be clinically significant.

Only significant when paired with secondary abnormalities like T-wave inversions.

Question 11

What other changes are typically seen in ventricular hypertrophy?

Answer 11

• Amplitude changes in ventricular depolarization.
• Secondary repolarization abnormalities
• Downsloping ST segment depression
• T-wave inversions

Abnormalities should be in the left lateral leads. (I, aVL, V5, V6)