Electrocardiography Revisited

Question 1

What is the clinical relevance of the ECG?

Answer 1

can identify conduction abnormalities, structural abnormalities and perfusion abnormalities

Question 2

Advantages to the ECG

Answer 2

relatively cheap
reproducible between people and centres
quick turnaround on results/report

Question 3

Downward deflections are towards which electrode?

Answer 3

anode (-)

Question 4

Upward deflections are towards which electrode?

Answer 4

cathode (+)

Question 5

An isoelectric line represents what?

Answer 5

no net change in voltage (i.e. vectors are perpendicular to the lead)

Question 6

Steepness of line denotes the (?) of an action potential.

Answer 6

velocity

Question 7

Width of the deflection denotes the (?) of the event.

Answer 7

duration

Question 8

What does the P wave represent?

Answer 8

electrical signal that stimulates the contraction of the atria (systole)

Question 9

What does the QRS complex represent?

Answer 9

electrical contraction that stimulates the contraction of the ventricles (systole)

Question 10

What does the T wave represent?

Answer 10

signifies relaxation of the ventricles

Question 11

SAN is made up of what type of cells?

Answer 11

autorhythmic myocytes

Question 12

SAN stimulates what?

Answer 12

atrial systole

Question 13

The PQ segment signifies?

Answer 13

AVN depolarisation

Question 14

Q wave represents?

Answer 14

septal depolarisation

Question 15

R and S wave represent?

Answer 15

R - ventricular depolarisation

S - late ventricular depolarisation

Question 16

ST segment represents?

Answer 16

fully depolarised

Question 17

T wave represents?

Answer 17

ventricular depolarisation

Question 18

Lead I includes what limbs?

Answer 18

left arm to right arm

Question 19

Lead II includes what limbs?

Answer 19

left leg to right arm

Question 20

Lead III includes what limbs?

Answer 20

left leg to left arm

Question 21

What is the rule of electrode reading?

Answer 21

left to right, top to bottom, first electrode of each pair is the anode (-ve)

Question 22

V1 is placed where?

Answer 22

right sternal border

4th intercostal space

Question 23

V2 is placed where?

Answer 23

left sternal border

4th intercostal space

Question 24

V3 is placed where?

Answer 24

halfway between V1 and V2

Question 25

V4 is placed where?

Answer 25

mid clavicular space | 5th intercostal space

Question 26

V5 is placed where?

Answer 26

anterior axillary line | at the level of V4

Question 27

V6 is placed where?

Answer 27

mid axillary line | at the level of V4

Question 28

What view of the heart?

Answer 28

ECG REVISITED LECTURE 1 TIMESTAMP 14.04

Question 29

Most commonly used lead is?

Answer 29

II

Question 30

How to calculate heart rate from ECG?

Answer 30

60/R-R interval = bpm

Question 31

List the augmented limb leads.

Answer 31

aVF aVL aVR

Question 32

The augmented limb leads use which electrodes?

Answer 32

fixed cathodes | virtual anodes

Question 33

What is the angle between an augmented lead and the limb lead that has it's virtual anode?

Answer 33

90 degrees

Question 34

Which limb leads and augmented leads are perpendicular to each other?

Answer 34

aVR - Lead III aVL - Lead II aVF - Lead I

Question 35

How to calculate axis with aVL and lead II?

Answer 35

``` find net deflection in both leads on ECG opposite side is Lead II adjacent side is aVL 90 degree angle use tan (x) find x report axis relative to zero zero to lead II is 60 0-x gives us axis ```

Question 36

Reference for zero is?

Answer 36

looking at the heart from the same viewpoint as lead I

Question 37

What other things to check when doing ECG?

Answer 37

Is it correct recording? Review signal quality and leads Verify voltage and paper speed Review patient background if available

Question 38

ECG reporting procedure

Answer 38

``` rate and rhythm P wave and PR interval QRS duration QRS axis (-30 to +90) ST segment QT interval T wave ```

Question 39

QRS axis can be varied (within normal -30 to +90) for what reasons?

Answer 39

tall, thinner person tilts more +ve | shorter, stockier person tilts more -ve