Week 1 Cardio

Question 1

what colour are the 4 limb leads

Answer 1

red (right), yellow (left), green (foot), black (neutral)

Question 2

what colour are the 6 chest leads

Answer 2

red, yellow, green, brown, black, violet

Question 3

chest lead positioning

Answer 3

v1: ICS4, Right Sternal Boarder
v2: ICS4, Left Sternal Boarder
v3: Between v2 and v4
v4: ICS5, left mid-clavicular line
v5: In line with v4, anterior axillary line
v6: In line with v4, mid-axillary line

Question 4

Which limbs do leads I-III use for electrodes (neg to positive), what are the viewing angles

Answer 4

I: aVR to aVL, 0º
II: aVR to aVF, 60º (towards pt’s bottom left)
III: aVL to aVF, 120º (towards pt’s bottom right)

Question 5

What is the calibration of an ECG

Answer 5

10mm/mV (height), 25mm/s (along)

Question 6

What does P wave show

normal duration, height and upright in

Answer 6

Atrial depolarisation
<0.12s
<0.25mV
Upright in Leads I, AvF, v3-v6

Question 7

What causes the PR segment

Answer 7

Delay at AV Node

Question 8

what is the PR interval, how long does it last

Answer 8

Atrial depolarisation and AV Node delay

0.12-0.2s

Question 9

What causes the QRS complex?

how long does it last?

Minimum amplitude in at least 1 limb lead?

Minimum amplitude in at least 1 chest lead (is there an upper limit)?

Positive in:
Negative in:

Answer 9

Ventricular Depolarisation:
<0.12s
Limb lead: >0.5mV
Chest lead: >1mV, upper limit is 3mV

Positive in: Leads I, II, v4-v6
Negative in: aVR, v1 and v2

Question 10

What is R?

Answer 10

Always the first positive reflection

Question 11

What is Q?

Answer 11

Any negative reflection that precedes the R wave

Question 12

What is S?

Answer 12

Any negative reflection that follows the R wave

Question 13

What is R’?

Answer 13

Any positive reflection after the R wave

Question 14

What is the QT interval?
How long does it last (in M/F)?
what physiological measurement can have an affect on the duration?

Answer 14

Whole ventricle action potential
<0.4s in males, <0.44s in females
Heart rate can affect QT

Question 15

What is QTc?

Answer 15

Rate corrected QT interval (using Bezett’s Formula)

Question 16

Normal QTc in M/F

Answer 16

<0.45s males, <0.47s in females

Question 17

What is the ST segment? Which point is it’s amplitude measured from?

Answer 17

Plateau phase of ventricular action potential

J point: where ST goes from mostly vertical to mostly horizontal

Question 18

What is the T wave?
Amplitude:
Direction relative to limb leads

Answer 18

Ventricular repolarisation
>0.2mV
same as QRS direction in 5 of 6 limb leads

Question 19

what to consider before the ECQ

Answer 19

Who’s the patient, When requested and why. Check calibration.

Question 20

How do you test rate?

Answer 20

(Big squares between R-R)/300

(Number of QRS complexes on a full strip) x6

Question 21

Way to measure rhythm

Answer 21

piece of paper: mark R waves and move along to see if they all match

Question 22

Normal axis is?

Axis deviation shows:

Answer 22

-30º to 90º

Hypertrophy/ or conduction abnormality

Question 23

Which leads are used to determine axis:

Answer 23

aVF and Lead I

Question 24

What combinations of lead directions show: Normal axis, left deviation, right deviation, extreme axis

Answer 24

Normal axis: Both Lead I and aVF positive
Left deviation: “leaving” aVF up, Lead I down
Right deviation: “reaching” aVF down, Lead I up
Extreme axis: both pointing down… very very bad

Question 25

What would you look for abnormality at the P wave? what would this show?

Answer 25

Absence for a P Wave = AF | Matching to QRS? if more than one P wave to QRS, atrial flutter

Question 26

What would you look for abnormality at the PR interval? what would this show?

Answer 26

prolonged (over 0.2s): certain heart blocks - 1st degree/ 2nd degree Mobitz Type 1 Shortened (under 0.12s): pre excitation syndromes (normally seen with broad QRS)

Question 27

What would you look for abnormality at the QRS complex? what would this show?

Answer 27

Is it narrow (normal), less than 0.12s? Broad could show: abnormal depolarisation (bundle branch blocks, ventricular ectopic beats) or pre-excitation (accessory pathways)

Question 28

What would you look for abnormality at the ST segment? what would this show?

Answer 28

J point in relation to Isoelectric line? Elevation in 2+ adjacent leads by 1mm in limb/ 2mm in chest leads: STEMI - ST Elevation Myocardial Infarction Depression of 0.5mm in 2+ leads indicates ischaemia

Question 29

What would you look for abnormality at the T wave? what would this show?

Answer 29

Tall and Tented? (More than Half the size of QRS OR pointed peak w/ narrow bottom) = Hyperkalaemia Inverted (this is normal in aVR and can be seen in v1 or III)? Ischaemia, BBBs, PE, Hypertrophic cardiomyopathy Flattened = non-specific ischaemia / electrolyte imbalance (hypokalaemia)

Question 30

What would you look for abnormality at the QT interval? what would this show? Care when prescribing what?

Answer 30

Prolonged QT can be due to Long QT Syndrome - a risk for life threatening arrhythmias Some medications prolong QT which could be fatal to patients with prolonged QT.