ECG I and II: Basic principles Flashcards Preview

Year 2 Cardiovascular > ECG I and II: Basic principles > Flashcards

Flashcards in ECG I and II: Basic principles Deck (43)
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1

where does the first depolarization event occur?

high left septum

2

the depolarization of the entire conduction system occurs in what segment of the ECG?

PR interval

3

does the SA node depolarization inscribe a surface ECG wave?

no

4

what does the PR interval reflect?

time of impulse conduction from AV junction to ventricular myocardium

5

why is the T wave upright at the same time the QRS complex is upright?

opposite event traveling in the opposite direction

(two negatives make a positive)

6

what is reflected by the QRS complex?

summation of all depolarization forces throughout both ventricles

7

what is reflected by the T wave?

summation of all repolarization events in both ventricles

8

ST segment corresponds to what phase of the cardiac AP?

phase 2

9

what is the standard paper speed?

25mm / sec

10

small squares count how much time?

0.04 s

11

large squares count how much time?

0.20 s

12

5 large squares count how much time?

1 s

13

what is a normal HR?

60-100 bpm

14

how do you check regularity? (2 methods)

1. R-R interval
2. same number of P waves as QRS complexes

15

what factors are checked to determine waves and complexes? (4 methods)

duration
amplitude
morphology
vector

16

what do the P waves record?

both atrial depolarizations

17

in which direction do the atria depolarize?

top right to lower left

18

what is the polarization of the P wave in avR (for normal sinus rhythm)?

negative

19

what is the normal duration of P waves?

less than 0.12 s

20

what is the typical voltage of P waves?

less than 25 mV

21

what is the best lead to look at P waves?

lead 2

22

the PR interval records events from what areas?

atrium through:

AVN
His
bundle branches
Purkinje fibers

23

what is the normal duration of the PR interval?

0.12 - 0.20 s

24

a PR interval over 0.20 s indicates what condition? is it pathologic?

first degree AV block

not necessarily pathologic; increases with age

25

what does a short PR interval mean?

pre-excitation

26

what is the normal duration of the QRS interval?

0.07 s - 0.11 s

27

a tall or deep QRS indicates what phenomenon?

increased muscle mass or chamber dilation

28

what does 'low voltage' mean?

less than 5mm in all limb leads

29

what is the normal duration of Q waves?

less than 0.03 s

30

Q waves are normal in which leads?

avR, II, III, avF, avL, V4-6