Intro to ECG (complete) Flashcards Preview

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Flashcards in Intro to ECG (complete) Deck (26):
1

Discuss the anatomy and function of cardiac structures responsible for generation and spread of cardiac depolarization which produce a normal heart beat

- SA node = pacemaker => where electrical impulses begin
- Then go through internodal tracts =>activates depolarization in atrium
- Goes to AV node => then brief delay
- then sent to bundle of His => activates ventricles (via left and right bundles)
- Spread to Purkinje fibers => activate ventricular cell depolarization and contraction

2

What is the significance of a P wave?

Atrial depolarization

3

What is the significance of a PR interval

- Measure AV node conduction time
- Normal PR is 0.12 to 0.20 seconds

4

What is the significance of the QRS complex?

Ventricular depolarization

Q = negative
R = positive
S = late negative deflection

5

What is the significance of the QT interval?

Total duration of depolarization and repolarization

6

What is the significance of a T wave?

Ventricular repolarization

7

What is the significance of a U wave?

Not supposed to be there! Indicates bad things!

8

Which leads monitor the RV?

V1, V2

9

Which leads monitor the LV?

V5, V6

10

Describe the EKG of ventricular hypertrophy

Remember: more muscle => more volts => greater amplitude in EKG

- Higher R wave
- T wave is negative

11

Describe the EKG of left ventricular hypertrophy

- Large positive R waves in V5 and V6
- Large negative S waves in V1

12

Describe the EKG of right ventricular hypertrophy

- Big R waves in right-sided leads (V1, V2)

13

Describe the EKG of myocardial ischemia

Blood supply is insufficient to meet O2 demands

- ∆s ventricular repolarization => affects ST segment & T wave

14

Describe the EKG of stress-induced myocardial ischemia in presence of fixed coronary obstruction

Depression of ST segment

- go look at ppt slide title "stressed-induced myocardial ischemia"

15

Describe the EKG of myocardial ischemia due to acute coronary artery obstruction during low O2 demand

T wave inversion

- Go look at ppt slide titled "during acute coronary syndrome"

16

Describe the EKG of myocardiac infarction

- Produces a Q wave (negative deflection in leads over myocardium)
- Needs to be present in multiple leads (must confirm it's actually an infarct of a specific area)

17

At what point does a Q wave indicate infarcted tissue?

1) ≥ 1/4 the amplitude of R wave
2) ≥ one small box wide (0.04seconds)
3) usually in at least 2 leads reflecting same region of left ventricle

18

At what point would you expect to see a peaked T-wave in the progression of a transmural myocardial infarct?

- At the very moment when the artery is obstructed completely
- You rarely see this in an ER (no one is there right away)

19

At what point would you expect to see a T-wave inversion in the progression of a transmural myocardial infarct?

- Happens very quickly
- You will usually see this in the ER (sometimes not though)

20

At what point would you expect to see ST elevation in the progression of a transmural myocardial infarct?

- Happens when you get a massive MI
- Involves to the whole frickin muscle (all layers)

21

At what point would you expect to see a Q-wave, ST-elevation, T-inversion in the progression of a transmural myocardial infarct?

- Means it's late in the MI progression
- Q wave indicates dead tissue
- Can see this only 14 to 24 hours after initial peaked T-wave

22

What's the difference between transmural and subendocardial MIs?

Transmural:
- ST elevation w/ Q waves
- Involve all layers

Subendocardial
- ST depression, no Q wave
- inner layer

23

Describe the EKG of hypercalcemia

Shortened QT

24

Describe the EKG of hypocalcemia

Lengthened QT

- may be associated w/ life threatening ventricular arrhythmias

25

Describe the EKG of hyperkalemia

- ^ T wave voltages (distinct peaked, symmetrical appearance)
- At higher levels => P waves flattened, QRS and T widened, a broad S wave
- At very high levels => sinusoidal pattern w/o P or R waves

A good time to go look at the ppt

26

Describe the EKG of hypokalemia

- Prolonged QT
- Prominent U waves frequent
- T waves inverted