Intro to ECG

Question 1

Direction of QRS

Answer 1

Q = negative

R = positive

S = late negative deflection

Question 2

normal duration of QRS

Answer 2

0.06-0.10 sec

Question 3

U waves are ____

Answer 3

inconsistent

Question 4

___ wave is inconsistent

Answer 4

U wave

Question 5

paper speed of ECG

Answer 5

25 mm/sec

Question 6

thin lines are ___ long and ___ sec

thick lines are ___ long and ___ sec

Answer 6

thin = 1 mm, 0.04 sec

thick = 5 mm, 0.20 sec

Question 7

PR interval means?

normal PR interval

Answer 7

PR interval = conduction time across AV node

normal PR interval = 0.12-0.20 sec

Question 8

Equation for HR

Answer 8

HR = 300/ # heavy lines between 2 QRS

HR = 1500/ # mm between 2 QRS

Question 9

Leads are electrodes that measure difference in electrical potential between ____

1)

2)

Answer 9

Leads measure difference in potential between

1) 2 diff points on body (bipolar lead)
2) 1 point on body and virtual reference point with 0 electrical potential (center of heart) = unipolar lead

Question 10

what is a unipolar lead

Answer 10

lead locate in center of heart (0 electrical potentail)

Question 11

Depolarization toward a positive electrode produces _____

Answer 11

positive deflection

Question 12

Direction of QRS based on left and lateral lead

vs. right sided leads

Answer 12

QRS in left/lateral lead = UPRIGHT (+)

QRS in right side lead = DOWNWARD (-)

Question 13

LOCATION OF bipolar Limb LEAD
1
2
3

Answer 13

1) BETWEEN BOTH HANDS (L = +, R = -)
2) BETWEEN R HAND AND L FOOT (HAND = -, FOOT = +)
3) BETWEEN L HAND AND L FOOT

Question 14

what are the bipolar limb leads

Answer 14

leads 1, 2,3 (standard limb leads)

Question 15

what are the bipolar precordial leads

Answer 15

NONE

Question 16

what are the unipolar limb leads

Answer 16

aVR, aVL, aVR (augmented limb leads)

Question 17

what are the unipolar precordial leads

Answer 17

V1- V6

Question 18

Direction of Augmented unipolar leads
aVL
aVF
aVR

Answer 18

aVL (L hand diagonally to right side) Hand = +

aVF (vertical down body)

aVR (R hand diagonally to left side) Hand = -

Question 19

which are the lateral leads

Answer 19

aVL and lead I

Question 20

which are the inferior leads

Answer 20

II, III, aVF

Question 21

which leads monitor the RV

Answer 21

V1 and V2

Question 22

which leads monitor the LV

Answer 22

V5 and V6

Question 23

signs of ventricular hypertrophy

Answer 23

more muscle = more volts = greater amplitude

Question 24

ECG changes in LVH

Answer 24

big R waves in L-sided leads

1, aVL, V5, V6

Question 25

ECG changes in RVH

Answer 25

big R waves in R-sided leads V1, V2

Question 26

What does depression of ST segment indicate?

Answer 26

ischemia due to sudden high O2 demand with fixed coronary obstruction

Question 27

what does ischemia due to high O2 demand due to coronary obstruction appear on ecg?

Answer 27

depression of ST segment

Question 28

what does T wave inversion indicate?

Answer 28

ischemia due to acute coronary artery obstruction and LOW OXYGEN DEMAND

Question 29

what does ischemia due to acute coronary artery obstruction and low O2 demand appear on ecg?

Answer 29

T wave inversion

Question 30

how does stress-induced myocardial ischemia appear?

Answer 30

normal at rest ST depression with exercise (inability to incr coronary flow appropriately and incr O2 consumption)

Question 31

how does acute coronary syndrome appear?

Answer 31

inverted T wave due to decr coronary flow without incr O2 consumption

Question 32

how does transmural current of injury appear?

Answer 32

ST elevation clot due to platelet clot

Question 33

what happens if you open up obstructed artery on ecg?

Answer 33

ST elevation can be partially or reversed

Question 34

what do Q waves mean?

Answer 34

transmural infarct (no transmural vector--> negative deflection)

Question 35

what is a significant Q wave

Answer 35

1) > 1/4 amplitude of R wave 2) > 1 small box (0.04 sec) wide 3) in @ least 2 leads (same area of LV)

Question 36

evolution of transmural MI

Answer 36

1) peak T wave (few min) 2) T wave inversion (ischemia) 3) ST elevation (current injury) 4) Q wave, ST elev, T inversion

Question 37

Transmural infarcts usually involve how much damage?

Answer 37

full thickness of LV wall = large

Question 38

transmural vs. subendocardial MI on ecg

Answer 38

transmural = ST elev with Q wave subendocardial = ST depression NO Q WAVE

Question 39

V1-V2

Answer 39

anteroseptal wall infarct

Question 40

V3-V4

Answer 40

anterior wall infarct

Question 41

V5-V6

Answer 41

anterolateral wall infarct

Question 42

II, III, aVF

Answer 42

inferior wall infarct

Question 43

I, aVL

Answer 43

high lateral wall infarct

Question 44

when is QT interval prolonged?

Answer 44

> 1/2 RR interval

Question 45

what are causes of prolonged QT

Answer 45

1) hypocalcemia, hypokalemia, hypomagnesium 2) class 1A or 3 anti-arrhythmic drugs 3) hypothermia

Question 46

if T wave merges with U wave what does that mean?

Answer 46

hypokalemia

Question 47

how does hypercalcemia appear on ecg?

Answer 47

shortened QT

Question 48

what is the most common cause of shorten QT interval

Answer 48

hyperparathyroidism --> hypercalcemia

Question 49

signs of hypokalemia

Answer 49

1) QT prolong | 2) T wave inverted

Question 50

changes in hyperkalemia K+ 5.5-7.5 mmol/L

Answer 50

tall T waves- peaked and symmetrical

Question 51

changes in hyperkalemia K+ 7.5-9.0 mmol/L

Answer 51

P & R waves flatten QRS & T broaden Big S wave

Question 52

changes in hyperkalemia K+ ? 9.0 mmol/L

Answer 52

P& R waves gone S and T broaden "sine wave"

Question 53

ABNORMALITIES IN THE QT INTERVAL AND T WAVE DUE TO DRUGS, ABNORMAL ELECTROLYTES, OR OTHER CAUSES PREDISPOSE TO ARRHYTHMIAS USUALLY THROUGH ___

Answer 53

alterations in repolarization