ECG Basics Again?

Question 1

Frontal plane is measured by?

Answer 1

hexaxial lead system - AVL,R,F 1,2,3 stuff.

Question 2

Horizontal plane measure by?

Answer 2

transverse leads 1,2…6

Question 3

How to determine regularity?

Answer 3

check R-R intervals - must be constant

Question 4

4 properties of waves and complexes that must be checked?

Answer 4

“D.A.M. Vector”

1) Duration
2) Amplitude
3) Morphology
4) Vector

Question 5

P-waves

• duration?
• amplitude?

Answer 5

<0.12sec (3 little boxes)

25mV

Question 6

Best leads to use for atria?

Answer 6

• Lead II (largest waves here bc on the axis of depolarization usually)
• Lead V1 (sits over both atria)

Question 7

Determining HR?

Answer 7

300
150
100
75
60
50
43
37
33
30

Question 8

PR interval

-duration

Answer 8

0. 12-0.2 sec (3 little boxes-5 little boxes)

- time inc with age

Question 9

PR interval is >0.2 sec this maens?

Answer 9

first degree AV block

Question 10

QRS complex

-duration?

Answer 10

0. 07-0.11 sec
   - measured from beginning of R to end of S
   - Amplitude varies a lot

Question 11

Q-wave

• duration?
• normal to see in which leads?

Answer 11

<0.03 sec

-avR, 2, 3, avF, avL, V4-V6

Question 12

If wide Q-wave this may indicate?

Answer 12

MI

must be 1/3 of accompanying R wave

Question 13

R-wave- amplitude V1-V6?

Answer 13

Amplitude inc from V1-V6

Question 14

S-waves amplitude V1-V6?

Answer 14

Amplitude decreases over V1-V6

Question 15

ST segment:

• positioning?
• represents?

Answer 15

• isoelectric - on 0mV

- represents short period when the ventricle remains depolarized

Question 16

St segment elevation means?

Answer 16

acute MI

Question 17

ST segment depression means?

Answer 17

repolarization abnormalities

Question 18

T-waves

-amplitude?

Answer 18

<10mm in V leads

Question 19

Inverted T-wave indicated?

Answer 19

MI

Question 20

Very large amp T-wave (larger than QRS)?

Answer 20

indicated a MI is going to happen

Question 21

U-waves?

• when? size?
• more noticeable when?

Answer 21

• small, rounded wave after T
• <10% size of T
• Noticed in: hypokalemia, some drugs like quinidine

Question 22

QTinterval measured how?

Answer 22

beginning of QRS to END of T wave

Question 23

What does QT interval measure:

Answer 23

duration of activation and repolarization of entire ventriclar myocardium`

Question 24

How do we correct for variability with QT interval?

Answer 24

QTc=QT + 0.00175(vent rate-60)

Question 25

QT duration?

Answer 25

varies with heart rate! (diastole shortens)

Question 26

Why are prolonged QTs importnant?

Answer 26

related to arrhythmias

Question 27

Mean QRS axis determination - method 1:

Answer 27

• find standard lead with net QRS vector most nearly equipotential
• look at the lead perp to the equipotential lead
• if the QRS in ther perp lead is positive the mean QRS axis is nearby
• if the QRS is the perpendicular lead is negative the mean QRS axis is 180 deg away

Question 28

Mean QRS axis determination - method 2:

Answer 28

• look at lead 1 and avF
• if 1 + and aVF+ –> normal axis
• if 1+ and aVF- –> leftward
• if 1- and aVF+ –> rightward