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):
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

31

the R wave comes from what area of the heart? it normally goes toward what lead?

high left septum?

lead I

32

which wave decreases in amplitude from V1-6?

S wave

33

which segment of the ECG recording is normally isoelectric?

ST

34

the ST segment represents what period?

when ventricle remains depolarized

35

what is the J point? what is the morphology? what does the morphology depend upon?

junction where QRS and ST segment merge

may be isoelectric, elevated, or depressed

repolarization abnormality

36

what do the T waves represent?

ventricular repolarization

37

what is the typical amplitude of T waves in limb leads?

less than 5 mm

38

what is the typical amplitude of T waves in V leads?

less than 10 mm

39

T waves are generally concordant with what part of the ECG recording?

QRS complex

40

what is one of the first events in acute MI?

elevated T waves

41

U waves are more noticeable in what circumstances?

hypokalemia
presence of quinidine and similar drugs

42

what does the QT interval represent? from where is it measured?

duration of entire cardiac cycle - activation and repolarization of entire ventricular myocardium (entire time it takes the heart to cycle one time)

beginning of QRS to end of T

43

what do prolonged QT intervals mean?

predispose to sudden death