Cardio: ECG basics Flashcards Preview

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Flashcards in Cardio: ECG basics Deck (40):
1

P wave represents

depolarization of the artria

2

QRS represents

depolarization of the ventricle (absolute refractory periord)

3

what cardiac myocyte action potential phases are represented by QRS

phase 0 and phase 1 (absolute refractory period)

4

Q

first downard deflection following P (not always present)

5

R

first upeard deflection of QRS complex

6

S

any negative deflection following and R wave

7

T wave represents

ventricular repolarization

8

apex of T wave represents what phase of cardiac myocyte action potential

phase 3 (relative refractory period)

9

what is a U wave

repolarization of purkinje fibers and papillary muscle - appearance of U wave is indirectly related to heart rate (usuallly seen in low HR - athletes)

10

J point

1.) first point of inflection of upstroke in S wave 2.) point at which ECG trace becomes more horizontal than verticle

11

where is PR interval measured

onset of P wave to onset of QRS

12

what does PR interval represent

time for impulse to travel from SA node to ventricles

13

what is the normal PR interval in adults? In kids?

Adults: 0.16-0.20 Kiddos: 0.12-0.20

14

PR segment is measured where

end of P wave to onset of QRS

15

PR segment represents

duration of contraction through bundle of his, bundle brances and purkinje fibers

16

RR interval represents

instantaneous heart rate

17

QT interval measured

onset of Q to end of T

18

QT represnets

electrical systole - duration of ventricular depolarization and repolarization

19

what is the normal QT interval

0.25-0.40

20

ST segement potential measurement

end of S wave to the inset of T wave

21

ST segment potential represents which phase of cardiac myocyte action potential

phase 2

22

location of V1 electrode

right of the sternum in the fourth intercostal space

23

location of V2 electrode

left of the sternum in fouth intercostal space

24

location of V4

left mid clavicular line in fith intercostal space

25

location of V6

left midaillary line

26

location of V3

between V2 and V4

27

location of V5

between V4 and V6

28

what is the normal value for QRS complex

0.06-0.10

29

left axis deviation occur between what angles

0 and -90

30

Extreme right axis devation occurs between what angles

Between -90 and + or 180

31

Right axis devation occurs between what angles

Between + (-) 180 and 90

32

what direction does depolarization occur

Endocardium to epicardium

33

In what direction does repolarization occur

from epicardium to endocardium

34

describe the wave progression in the chest leads

R waves get bigger from V1 to V6, S waves get smaller from V1 to V6

35

how do you do a quick estimate of normal QT interval

normal QT should be less than half of the preceeding RR interval

36

Mean QRS in hypertrophy

mean QRS toward the hypertrophied side - why? Hypertrophied side will have greater depolarization activity

37

Mean QRS in infaction

mean QRS AWAY from the infarct. Why? The necrotic tissue does not depolarize

38

Mean QRS in bundle block

TOWARDS the block

39

Pathological Q wave

greater than 3 mm or greater than 25% of the R wave

40

what do you see on ECG in the recovery phase of infarct

ST segment and T wave return to normal but pathological Q wave can persist for months