Exam 1 nuggets

Question 1

Why does lead I have a more pronounced q wave then lead II?

Answer 1

Lead I is closer to the left side of the heart, and the vector is moving AWAY.

Question 2

What does the T wave look like in lead V1 vs V6? Why?

Answer 2

T wave is often inverted in lead V1 d/t small R wave

T wave is positive in lead V6 because the R wave is large.

Question 3

Explain the evolution of an MI.

Answer 3

1a Hyperacute T waves
1b T wave inversions (often skipped)
2. QT elevation
3. Pathologic Q wave formation (irreversible damage)

Question 4

Which hypertrophy/enlargement corresponds to Mc-donald’s “M’s” on P wave?

Answer 4

Left atrial enlargement (hump after Left atrial depolarization).

Question 5

If this lead has an R wave > 11 mm, the patient has LVH

Answer 5

aVL
unless the patient is >35 yo and does not have repolarization abnormalities

Question 6

What changes are common ventricular hypertrophy (both RVH and LVH) and what leads do you see them in?

Answer 6

Repolarization anormalities

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

Seen in left lateral leads. (I, aVL, V5, V6) for LVH
Seen in right sided leads (V1 and V2 sometimes) for RVH

Question 7

In what leads are T-wave inversions normal? Why?

Answer 7

V1, V2, and V3 in children and black athletes with persistent juvenile T-wave abnormality

Remember - V1-V3 have smaller R waves, making the leads more likely to have inverted T waves!

Question 8

What are the stages of hyperkalemia and how do you differentiate it from an MI?

Answer 8

1. Starts with tall, peaked T waves (that are not broad like hyperacute T waves of an MI). Very diffuse with no reciprocal T wave inversions!
2. QRS widen (more than 2 boxes) and T waves get taller and broader
3. Sine wave pattern - shark teeth - difficult to evaluate what is what (profound hyperkalemia)

Question 9

Evolution of hypokalemia

Answer 9

1. Presence of U wave > T wave
2. Flattened T wave, Presence of U waves, prolonged QT segment (everything is flat) - lose T-wave shape

Question 9

When is a U wave pathologic? What does it mean?

Answer 9

If the U wave is larger than the T wave

Indicates hypokalemia

Question 10

What do you see in pericarditis?

Answer 10

1. J point elevation (perry, jeremy)
2. Diffuse ST elevation with no reciprocal ST depression
3. PR segment depression

Question 11

What is the pattern in PE?

Answer 11

S1Q3T3

Lead 1 has an S wave
Q wave and T wave inversion in lead 3

Question 12

When is a large T wave abnormal?

Answer 12

If the QRS complex is not extremely large as well (aka the T wave is a similar size as the QRS complex).

Question 13

What differs T waves in hyperkalemia and stemi?

Answer 13

Hyperkalemia = peaked and narrow
Stemi = wider

Question 14

What differs T wave inversions in MI from repolarization abnormalities?

Answer 14

T wave inversions are symmetric in stemi, while there is a more down slope linear into the inverted T wave for repolarization abnormalities

Question 15

What is an NSTEMI on EKG?

Answer 15

Just ST reciprocal changes withOUT ST elevation

Question 16

How many leads do you need to diagnose a STEMI?

Answer 16

Just the majority (3/4 or 2/3)

Question 17

If you have a posterior STEMI, what do you see on EKG?

Answer 17

Inferior ST elevation with out-of-proportion reciprocal changes in the anterior leads (out-of- proportion ST depression in anterior leads)

Question 18

In order to have RAE, what does V1’s P wave need to be? Lead 2’s P wave?

Answer 18

Should be predominantly positive
Lead 2 should be >2.5 mm

Question 19

If you have an isoelectric lead, where is the main axis?

Answer 19

+/- 90 degrees

Question 20

What are the repolarization abnormalities?

Answer 20

T wave inversion and ST segment depression in the hypertrophied leads

LVH = problems with V5, V6, lead 1, and aVL (sometimes lead 2)

RVH: V1, V2

Question 21

What is common to see in aVL if you have RVH?

Answer 21

It is negative (because we are saying the right side of the heart hogs most of the electricity)

RVH is not black and white

Question 22

If you are unsure what a wave is in a lead, what can you do?

Answer 22

Look at the lead above or below and match the wave - it all happens at the same time!

Question 23

Why is case 70 not RAE, LAE, and LVH?

Answer 23

Idk, check!

Question 24

Explain the electrical system of the heart

Answer 24

SA Node –> AV Node

AV node has bundle of His which breaks off into the right bundle branch and the left bundle branch

Left bundle branch breaks off into the septal fasicle, left posterior and left posterior fasicle and. The left bundle branch then becomes the left anterior fasicle

Question 25

What are the 3 types of cells that make up the electrical system of the heart?
The waves on the EKG reflect the electrical activity of which type of cells?
The waves on the EKG are manifestations of what two processes?
Which axis on the EKG measures time?
How much time does one small square represent?
How much voltage does one large square represent?

Question 26

What does septal depolarization look like in right sided leads vs lateral (left ) leads?

Answer 26

Small R wave in right sided (charge moves towards it)
Small Q wave in left (charge moves away)