cardio management

Question 1

What is an ECG?

Answer 1

• a recording of potential changes, detected by electrodes on the body surface
• allows the electrical activity of the heart to be monitored

Question 2

What information does the ECG provide?

Answer 2

• information about cardiac rate and rhythm, chamber size, the electrical axis of the heart
• it is the main test to assess for myocardial ischaemia and infarction

Question 3

current flowing in the extracellular fluid gives rise to the current monitored on the ECG T/F?

Answer 3

True

Question 4

charges that are separated constitute an ……… dipole which is a …… with components of magnitude and ………..

Answer 4

electrical/vector/direction

Question 5

Why is the electrical vector of clinical significance?

Answer 5

• allows the electrical axis of the heart to be estimated

Question 6

How is magnitude determined?

Answer 6

• by the mass of cardiac muscle that is involved in the generation of the signal (thus the atria and ventricles dominate)

Question 7

How is direction determined?

Answer 7

• by the overall activity of the heart at any instant in time and varies during the cardiac cycle

Question 8

When a depolarisation moves towards the recording electrode, it generates an …… deflection on the ECG?

Answer 8

Upward

Question 9

When the depolarisation moves away from the recording electrode it generates a ……. deflection on the ECG?

Answer 9

downward

Question 10

What happens when there is no movement towards or away from the recording electrode?

Answer 10

• There is no deflection on the ECG

- it is called an isopotential

Question 11

Where are the 3 standard limb leads?

Answer 11

I: RA to LA
II: RA to LL
III: LA to LL

Question 12

How does lead II ‘see’ the heart?

Answer 12

from an inferior direction

Question 13

What is the normal duration of the P wave?

Answer 13

less than 0.08-0.10 ms

Question 14

What is the normal duration of the QRS complex?

Answer 14

0.01 ms or less (3 small boxes on ECG)

Question 15

What causes each part of the QRS wave?

Answer 15

Q - depolarisation in the inter ventricular septum
R - depolarisation of the main free walls of the ventricles
S - ventricles at the base of the heart depolarise

Question 16

What does the PR interval represent and how long is it normally?

Answer 16

• reflects the time for the SA node impulse to reach the ventricles
• 0.12-0.2 seconds

Question 17

What are the 3 augmented limb leads?

Answer 17

aVR, aVL, AVF

Question 18

what are the lateral leads and what does this mean?

Answer 18

• I and aVL

- means that each has the recording electrode on the left arm and views of the heart are from the eft

Question 19

What are the inferior leads and what does this mean?

Answer 19

• II and III and aVF

- means each has the recording electrode on the left foot and views the heart from an inferior direction

Question 20

How do V1-V6 leads ‘view’ the heart?

Answer 20

On a horizontal plane

Question 21

Which leads look at the inter ventricular septum?

Answer 21

V1 and V2

Question 22

What do leads V3 and V4 look at

Answer 22

the anterior of the heart

Question 23

What do V5 and V6 look at?

Answer 23

the lateral aspect (left ventricle) of the heart

Question 24

How can HR be calculated using an ECG?

Answer 24

300/number of large squares between R-R interval

Question 25

What is the ECG rhythm strip?

Answer 25

• prolonged recording of 1 lead
• usually lead 2
• allows you to determine HR and cardiac rhythm