Electrocardiography

Question 1

What is an ECG

Answer 1

a diagnostic tool used to measure the electrical activity of the heart, summation of activity, consisting of 10 leads minimum, recorded from electrodes on the body’s surface, produces 12 traces

Question 2

What do leads AVF, AVR & AVL measure?

Answer 2

AVF- inferior regions such as feet
AVR-measure right side of heart through the right arm
AVL- measures left side of heart through left arm

Question 3

What do leads i,ii & iii measure?

Answer 3

i- left side of heart (left arm to right arm)
ii-left leg to right arm
iii-left leg to left arm

Question 4

What does lead V1,V2,V3,V4,V5 & V6 measure?

Answer 4

V1- 4th intercostal RSE (Rv and inv septum, anteroseptal surface V1-V3, red lead)
V2-4th intercostal space LSE (RV and septum, yellow lead)
V3- midway between 2&4th (records anterior wall of LV, green lead)
V4- 5th intercostal mid clavicle (v4-v6 measures anterolateral surfaces, v4 anterior wall of LV, brown lead)
V5-left ant axillia at v4 level (records lateral wall of LV, black lead)
V6- mid axillia (armpit) at V4 level (purple lead,

Question 5

What is a bipolar lead?

Answer 5

A lead composed of two electrodes of opposite polarity is called bipolar lead, (lead i, ii, iii), recording from two different sites

Question 6

What is a unipolar lead?

Answer 6

A lead composed of a single positive electrode and a reference point is a unipolar lead. (AVR, AVF,AVL and V leads)

Question 7

How to prepare a patient for an ECG

Answer 7

Explain the procedure, and details (DOB, name & hospital number) and answer any questions, ensure the patient is relaxed and has a bare chest, clean the skin, shave the chest and remove oils. gently abrade, take off the top layer of dead skin

Question 8

Danger’s of ECG

Answer 8

Results need to be reproducible
differently, if ECG is done differently the results will look different and interpretation will be different

Question 9

Difference between diagnostic and monitor ECG

Answer 9

A diagnostic ECG consists of a minimum of 12 leads and a frequency between 0.05-150Hz, whereas a monitor ECG consists of 1-2 leads and has a frequency of 40Hz

Question 10

Why a patient has been referred for an ECG

Answer 10

could be due to:
chest pain
acute MI
Pulmonary embolism
dizziness
arrhythmias
drug efficacy
pre-operation

Question 11

What is a pulmonary embolism

Answer 11

The thrombus in lower limbs breaks off and gets stuck in a lung artery. Starts in a deep vein in the leg which travels to the lungs

Question 12

What is syncope

Answer 12

someone coming in and out of consciousness

Question 13

What is an arrythmia

Answer 13

any person not within sinus rhythm, e.g., fibrillation

Question 14

How to prepare ECG equipment

Answer 14

make sure to calibrate the machine 1mv/10mm for every 1mv the pen will move 10mm, the paper speed should be 25mm/s, frequency response 0.05-150Hz

Question 15

Paper speed importance

Answer 15

it can make a patient’s rhythm look different, can make them look bradycardic/ tachycardic

Question 16

Calibration needs to change when?

Answer 16

if complexes are overlapping, makes ecg look taller or shorter

Question 17

Frequency can be changes when?

Answer 17

eradicate electromagnetic waves, make sure to write on ECG change in settings

Question 18

Lead I attachment & colour

Answer 18

Left arm attached to pos electrode (yellow)
right arm attached to neg electrode (red)

Question 19

Lead II attachment & colour

Answer 19

the right arm is positive electrode
left foot is negative electrode (green)

Question 20

lead III attachment & colour

Answer 20

Left arm to left foot
Left arm is negative and left foot is positive (green)

Question 21

electrode attachment on right leg

Answer 21

The right leg is neutral, will improve the quality of the signal, remove artefacts

Question 22

What is a differential amplifier

Answer 22

amplifies difference between inputs

Question 23

aV stands for

Answer 23

Augmented voltage

Question 24

How many traces produced by aV electrodes

Answer 24

6 traces produced by aV electrodes

Question 25

Angle of louis

Answer 25

Fusion between the sternum and manubrium

Question 26

breast tissue ecg

Answer 26

Lift breast tissue with the back of hand to place V4 & V5 and lower breast tissue back down, ECG cannot be done with a bra on

Question 27

V4R

Answer 27

mirror position, applied on pediatrics, as heart is further right and swings round as it growsr

Question 28

V7, V8 and V9

Answer 28

V7- left posterior axillary line
V8-mid scapular line (in line with V6)
V9- Paravertebral line (Same level as V6)

Question 29

What plane do chest leads measure in?

Answer 29

the horizontal plane of the heart

Question 30

What plane do limb leads measure in?

Answer 30

they observe the heart in the frontal plane

Question 31

What is the Hexaxial reference system?

Answer 31

This system allows us to determine how the heart lies electrically, can give information about the axis of the heart, Lead i,ii,iii and AVF, AVR &AVR allows axis deviations to be spotted.
If the pen moves up signal moves towards an electrode
if the pen moves down signal moves away from the electrode

Question 32

AVL is perpendicular to?

Answer 32

Lead II

Question 33

Lead III is perpendicular to?

Answer 33

AVR

Question 34

Lead I is perpendicular to?

Answer 34

AVF

Question 35

What does the P wave represent?

Answer 35

Atrial depolarization

Question 36

What does QRS wave represent?

Answer 36

Ventricular depolarization, no QRS in V2, RS complex instead

Question 37

What does the T wave represent?

Answer 37

ventricular repolarization

Question 38

What is AC mains?

Answer 38

How well the equipment is maintained, poorly maintained equipment masks the ability to interpret data, zigzag harsh lines

Question 39

What is baseline wander

Answer 39

picked up on ECG, if patient has baggy lungs, or poor contact to electrodes, records rising and falling of chest
a wave on ecg

Question 40

What is somatic

Answer 40

nervous activity picked up, the patient may be laying uncomfortably, interferes with ecg,