Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Y1 TP2 Cardiovascular (topic 4 Onwards) > 6. ECG basics And Leads > Flashcards

6. ECG basics And Leads Flashcards

1
Q

SA node

A

—> generate action potentials (depolarising currents) that are transmitted by channels to certain areas causing muscles to contracts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Impulse conducting system of the heart -steps

A
  1. The depolarising (+ve) current is generated in SA node
    1. Spreads to Atrium and then to the AV node
    2. From the AV node the +ve current moves to bundle branches depolarising the interventricular septum
    3. The +ve current then moves to the purkinje fibers depolarising the ventricles (causing ventricles to contract)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Repolaraisation

A
  • The depolarising wave is immediately followed by repolarising (-ve) current
  • Atria begin to repolarise when ventricles are depolarising
  • Ventricles repolarise before the next wave of depolarisation begins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

ECG - what is it

A
  • Graphical representation of electrical activity of the heart
  • The electrodes placed in the body captures movement of ions and records it
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

3 charges

A

Positive deflection
Negative defection
Isoelectric point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Positive charges

A
  • positive deflection = +ve current moving towards +ve electrode will give a +ve deflection -
    • neglative deflection +ve current moving away from +ve electrode will give a -ve deflection
    • isoelectrric point/ straight line +ve current moving perpendicular to the electrodes will give isoelectric line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Negative charges

A
  • Positive deflection = -ve current moving towards -ve electrode will give a +ve deflection
    • Negative electrode = -ve current moving away from -ve electrode will give a -ve deflection
    • Isoelectric point/ straight line = -ve current moving perpendicular to the electrodes will give isoelectric line
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Lead II

A

—-> used as a rhythm strip = as it has a more prolonged time period of 10seconds
• Used to determine rate and rhythm of heart beat

Most commonly used to produce the normal sinus rhythm (NSR) tracing
• -ve electrode placed in right arm and +ve electrode in left leg

Waves
• Pqrst
• Rarely may get a u wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

P wave

A

• Formed by atrial depolarisation

SA node generate positive charge and sends it down depolarising the atria
• Red arrow is the net movement of the charges towards the av node
• Positive charges move towards positive electrode = positive deflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

P-R interval

A

In the AV node the positive charges remain ‘ there for 0.1 seconds
• 0.1 s delay in conduction in AV node leading to P-R segment
• +ve charge is not moving!
Isoelectric line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Q wave

A

—> septal depolarisation

• Positive charges move down into bundle branches 
• Left bundle branch receives positive charges first  = Left bundle branch depolarises the interventricular septum and right bundle branch

• Positive charges move away from positive electrode = negative deflection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

R wave

A

ventricular (apex) depolarisation

  • Left bundle depolarises interventricular septum and right bundle
    • After right bundle is depolarised charges move down and depolarise ventricular apex
    • More depolarisation happens in left ventricle than right due to its thicker wall
    • So movement of positive charges are more towards left ventricle = movement more towards positive electrode

• Atria begin to repolarise as ventricles are depolarising: but this repolarising wave is ‘hidden’ within the big R wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

S wave

A
  • Positive charges move up to lateral walls o’f ventricles
    • Positive charges move away from potisitve electrode = negative deflection

• Purkinje fibers depolarises the walls of the ventricles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

S- T segment

A
  • Short delay before ventricular repolarisation
    • Isoelectric line
  • Entire ventricular myocardium is depolarised and is not repolarised yet.
  • No net movement of ions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

T wave

A

—> ventricular repolaraisation

• Repolarization = all positive charges become negative 
	○ Negative ions move away from positive electrode and up towards negative electrode = negative reflection
  • Negative charge moving towards the negative electrode giving a positive deflection
  • QT interval: time taken for ventricular depolarisation and repolarisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Rare u wave

A

• Due to repolarisation of papillary muscles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

ECG electrodes

A
  • Clinical ECG recording typically uses 4 limb electrodes and 6 chest electrodes
  • Leads are also called views
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

The three bipolar limb leads

A

–> 3 limb leads in the legs or arms, organised in a triangle
• Leads I, II, and III can be represented schematically in terms of a triangle, called Einthoven’s triangle

19
Q

Lead 1

A
  • -ve electrode in right arm
    • +ve electrode in left arm
    • Looking at the heart from slightly above = High lateral wall of left ventricle
20
Q

Lead 2

A
  • -ve electrode in right arm
    • +ve electrode in left leg
    • Looking at the heart from the base – inferior rv and lv
21
Q

Lead 3

A
  • -ve electrode in left arm
    • +ve electrode in left leg
    • Looking at the heart from the base – inferior rv and lv
22
Q

What is the view from a lead

A

Look at the +ve lead to determine where info is connecting

23
Q

Lead I waves

A

• Same waves as lead 2 but lower amplitude

24
Q

Lead Il waves

A

• Same waves as lead 3

25
Q

Lead Ill waves

A

• Same waves as lead 2 but lower amplitude

26
Q

Lead equation

A

• The bipolar leads are related by the ‘ equation: Lead I + Lead III = Lead II
Good way to check if electrodes are in the right place
Lead 2 waves should look like lead 1 and 3 waves together

27
Q

How leads view heart

A

• The area of heart covered by the leads:
—-> ecg focuses on the ventricles

– Lead I: High lateral wall of left ventricle
– Lead II and III: Inferior portion of right and left ventricle

As lead 2 and lead 3 have the same view, they will have same wave view but just at different amplitudes

28
Q

3 Augmentated unipolar limb leads

A

aVR - right arm -
aVL - left arm
aVF - foot

29
Q

aVR

A
  • Augmented vector right
    • -ve electrode on left arm
    • -ve electrode on foot
    • +ve electrod in right arm
    • Look from the +ve electrode – augmented view from the right side
    • Gives a triangle
    • Waves are an opposite pattern
30
Q

aVL

A
  • +ve elctrodre on the left arm
    • It is looking from the left side like lead 1 - it has the same wave pattern as lead 1 (2 and 3)
    • Location is looking at high lateral wall of left ventrical like lead 1
31
Q

aVF

A

• +ve foot

* Same wave patternas lead 2 (1 and 3)
* As it is looking from same direction as lead 2 – inferior wall of ventricles)
32
Q

aVR waves

A

The area of heart covered by the aVR:
– Right ventricle and basal septum

• ECG tracing waves will be the opposite of lead I, II and III
Almost reflected
All waves are interved
Pqrst

33
Q

aVL waves

A

• The area of heart covered by the aVL:
– High lateral wall of left ventricle

• ECG tracing similar to lead I, II and III

34
Q

aVf waves

A

• The area of heart covered by the aVF:
– Inferior wall of the heart

• ECG tracing similar to lead I, II and III

35
Q

Six precordial chest leads - what are they

A

—> these leads are unipolar- have only one positive electrode

36
Q

V1

A

– V1: Right 4th intercostal space

37
Q

V2

A

– V2: Left 4th intercostal space

38
Q

V4

A

– V4: Left 5th intercostal space, midclavicular line

39
Q

V5

A

– V5: Left 5th intercostal space, anterior axillary line (where the clavicle is ending)

40
Q

V6

A

– V6: Left 5th intercostal space, mid axillary line (middle of armpit)

41
Q

V3

A

– V3: Between V2 and V4

42
Q

Six precordial chest leads - which parts of the heart are covered

A

– V1-V2: Right ventricle
– V2-V3: Basal septum
– V2-V4: Anterior wall of the heart
– V5-V6: Lateral wall of the heart

43
Q

Six precordial chest leads - the waves

A

Same waves pqrst

– R-wave increase in size from V1- V6
• V1 has small r wave
• V2 has large r wave

– S-wave decrease in size from V1-V6
• V1 has large s wave
• V6 has small s wave

Y1 TP2 Cardiovascular (topic 4 Onwards) (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions