Brainscape's Knowledge GenomeTM

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


See full index

2 - Sarah's CVS > The Electrocardiogram > Flashcards

The Electrocardiogram Flashcards

1
Q

What does the P wave represent?

Why is it a small upward depolarisation?

A

Atrial depolarisation

Due to: smaller muscle mass and depolarisation moving towards the electrode

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

What does the QRS complex represent?

A

Ventricular contraction

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

What does Q represent?

A

Septal depolarisation spreading to ventricles

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

What does R represent?

A

Main ventricular depolarisation

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

What does S represent?

A

End of ventricular depolarisation

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

When does atrial repolarisation take place?

A

During the same time as ventricular depolarisation

– during QRS complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the T wave represent?

A

Ventricular repolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the T wave shape

A

Upward signal as repolarisation is away from electrode

Medium sized as timing in the different cells is dispersed

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

What does the PR interval measure?

A

Time taken for impulse to reach ventricles from the SA node

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

What is a normal time for a PR interval?

A

0.12 to 0.2 seconds

3-5 small squares

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

What does a short PR interval indicate?

A

Atria have been depolarised close to the AV node or the is an abnormality of conduction from the atria to the ventricles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does the duration of the QRS complex represent?

A

How long excitation takes to spread through the ventricles

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

What is the normal duration of a QRS complex?

A

0.12 seconds or less

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

What does a widened QRS complex represent?

A

An abnormality of conduction through the ventricles

E.g. Bundle branch block

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the V leads?

A

Six chest leads
Made from 6 positions overlying the 4th and 5th rib spaces
– look in horizontal plane from the front and from the left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do V1 and V2 show?

A

Right ventricle

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

What do V3 and V4 show?

A

Septum and anterior wall of left ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do V5 and V6 show?

A

Anterior and lateral walls of left ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the cardiac axis?

A

The average direction of spread of the depolarisation wave from the front

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where can you deduct the cardiac axis?

What is the normal shape?

A

From leads I, II and III

Defects signal upwards as depolarisation is spreading towards the three leads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When does right axis deviation occur?

What is it associated with?

A

When the right ventricle becomes hypertrophied.

Usually associated with pulmonary condition putting a strain on the right side of the heart as well as congenital heart defects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What do you see form the leads in right axis deviation?

A

Deflection in I becomes negative
Deflection in III becomes positive

– axis swings towards the right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

When does left axis deviation occur?

What is it usually due to?

A

When the left ventricle becomes hypertrophied

Usually due to a conduction defect
– unlikely to be due to increased bulk of left ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What do you usually see from the leads in left axis deviation?

A

QRS complex become negative in III

Only is significant when QRS deflection is predominantly negative in lead II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is first degree heart block?

A

Prolonged PR interval

26
Q

What is first degree heart block a sign of?

A

Coronary artery disease
Acute rheumatic carditis
Digitalis toxicity
Electrolyte disturbances

27
Q

What is second degree heart block?

A

Erratic PR interval

Excitations fails to pass through the AV node or the bundle of His

28
Q

What are the causes of second degree heart block?

A 
Same as first degree heart block: 
Coronary artery disease
Acute rheumatic carditis
Digitalis toxicity
Electrolyte disturbances
29
Q

What is third degree heart block?

A

Complete atrioventricular block

    • atrial contraction is normal but no beats are conducted to the ventricles
    • the two are disconnected electrically
30
Q

How are the ventricles excited in third degree heart block?

A

By a slow escape mechanism

31
Q

How can you recognise third degree heart block?

A

P wave rate is normal (90)
QRS rate is low (36)
No relationship between P and QRS
Abnormal shaped QRS complexes due to abnormal spread of depolarisation from ventricular focus

32
Q

What can cause third degree heart block?

A

Acutely – transient heart attack

Chronically – fibrosis around bundle of His

33
Q

When can a right bundle brach block be normal?

A

When the duration of the QRS complex is normal

34
Q

What do bundle branch blocks indicate?

A

RBBB indicates problems with the R side of the heart

LBBB always indicates heart disease, usually on the L side

35
Q

What changes occur in the ECG during right bundle brach block?

A

V1 lead – normal R wave, second R wave due to failure of conduction pathway
V6 lead – smaller Q wave, normal R wave, wide deep S wave

36
Q

What changes occur in the ECG during left bundle brach block?

A

V1 lead – small Q, R wave (inspire of smaller mule mass), S wave (late depolarisation of LV)
V6 lead – R wave, S wave (appears as a notch), second R wave (due to late depolarisation of LV)

37
Q

Where is right bundle brach block most easily seen?

A

In V1, where there is an RSR pattern

38
Q

Where is left bundle brach block best seen?

A

In V6 where there is a “rabbit ears” pattern

39
Q

Describe the branching of the bundle of His

A

From the AV node, two branches arise. The right bundle branch and the left bundle branch.
The right bundle branch has no main divisions.
The left bundle branch has two main divisions – anterior and posterior fascicles

40
Q

Which pacemaker cells have priority?

A

SAN pacemaker cells. They pre-empt other pacemakers due to a faster firing rate.

41
Q

What can you use in order to determine the cardiac axis?

A

The lead with the smallest possible R wave which will be the lead at 90 degrees to the cardiac axis.

42
Q

When analysing an ECG what do you look for?

A 
Rate
Rhythm
Axis 
P wave
P-R segment
QRS complex
Q-T interval 
T wave
43
Q

When is the P wave absent?

A

In atrial fibrillation

44
Q

What are abnormalities that can be seen in the P-R interval?

A

First degree heart block = prolonged P-R interval
Second degree heart block = erratic P-R interval
Third degree heart block = no relationship between P and QRS complex

45
Q

What is sinus rhythm?

A

Pacemaker cells in the SAN are controlling the heart rate

– normal depolarisation

46
Q

What are the features of myocardial infarction?

A

ST elevation
Pathological Q waves – greater than one small square across
Inverted T waves

47
Q

What changes from the MI are permanent?

A

Pathological Q waves are permament
– present in full thickness MI
– due to scar tissue forming which effectively blocks the circuit
Inverted T waves

48
Q

What do broader QRS complexes represent?

A

Escape rhythm

– ventricle is taking over as the pacemaker

49
Q

Where can you see an inferior MI?

Which coronary artery is likely to be responsible?

A

Leads II, III and aVf

Right coronary artery

50
Q

Where can you see an anteroseptal MI?

Which coronary artery is likely to be responsible?

A

V1 and V2

Left anterior descending coronary artery

51
Q

Where can you see an anteroapical MI?

Which coronary artery is likely to be responsible?

A

V3 and V4

Distal left anterior descending coronary artery

52
Q

Where can you see an anterolateral MI?

Which coronary artery is likely to be responsible?

A

V5, V6, I, aVL

Circumflex coronary artery

53
Q

Where can you see an extensive anterior MI?

Which coronary artery is likely to be responsible?

A

V1 - V6, I, aVL

Proximal left coronary artery

54
Q

Where can you see a posterior MI?

Which coronary artery is likely to be responsible?

Wat are you likely to see in this case?

A

V1 and V2

Right coronary artery

ST depression in anterior leads or as tall R waves

55
Q

Where is the MI if there are changes in leads II, III and aVf?

A

Inferior

56
Q

Where is the MI if there are changes in leads V1 and V2?

A

Anteroseptal

57
Q

Where is the MI if there are changes in leads V3 and V4?

A

Anteroapical

58
Q

Where is the MI if there are changes in leads V5, V6, I and aVL?

A

Anterolateral

59
Q

Where is the MI if there are changes in leads V1 - V6, I and aVL?

A

Extensive anterior

60
Q

Where is the MI if there are tall R waves in V1 and V2?

A

Posterior aspect

2 - Sarah's CVS (13 decks)

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