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Unit 12 > ECG made easy > Flashcards

ECG made easy Flashcards

1
Q

What are the different waves on an ECG?

A

Yellow - p wave
Orange - Q wave
Red - R wave
Blue - S wave
Green - T wave

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2
Q

What are the different numbered sections on an ECG called?

A

1 - PR interval
2 - PR segment
3 - QRS complex
4 - ST segment
5 - ST interval
6 - QT interval

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3
Q

How do you annotate a repeated wave in an ECG?

A

R’ T’ etc indicates the second on one of these waves/

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4
Q

Explain what is meant by the cardiac axis.

A

The overall direction (or vector) of electrical activity during ventricular depolarisation of the heart.
This is normally in close alignment with lead 2.

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5
Q

What do the main waves in an ECG represent?

A

P wave = atrial depolarisation
QRS complex = ventricular depolarisation
T = ventricular repolarisation

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6
Q

How does the QRS axis tend to present on the six limb leads?

A

Positive in lead 1,2,3, aVF,avL - greatest positive in lead 2
Negative in avR.
At travelling towards apex of the heart.

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7
Q

How can we determine from an ECG is the cardiac axis is normal?

A

Both the polarity of lead 2 and lead 1 QRS will be positive. This indicates a normal cardiac axis between -30 and +90 degrees.
If this is not true the axis is abnormal, may be left deviation, right deviation or extreme deviation

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8
Q

What is the clinical importance of having a positive deflection P wave in lead 1 and lead 2?

A

Indicates the electrical activity is originating from the SAN.

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9
Q

What areas on an ECG paper are different ECG leads found?

A

Bottom most across whole length - rhythm strip, this is normally set to be lead 2
Remaining 12 leads are splits into 6 to the left which are limb leads and 6 to the right which are chest leads.

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10
Q

How are the different areas of the heart represented on an ECG by what lead?

A

Lead 1, aVL, V5, V6 - represent the lateral view of the heart
Lead 2, 3, aVF represent the inferior surface of the heart
And V1, V2, V3 - represent the antior surface of the heart

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11
Q

What are the important measurments of time on an ECG?

A

One small sqaure is 40ms
Five small sqaure is 200ms = One big square os 0.2 seconds
Five big squares is one second
Therefore the width of one ECG strip tends to be ten seconds

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12
Q

What are the important measurements on an ECG relating to amplitude?

A

2 large sqaures is 1mv
Therefore 1 small sqaure is 0.05 milivolts.

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13
Q

What are the features of a PR interval on a normal ECG?

A

Should be 120 to 200 ms long
This is 3 to 5 small sqaures

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14
Q

What are the main pathologies associated with a prolonged PR interval?

A

1st degree and 2nd degree heart block

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15
Q

What are the normal features of a QRS complex on an ECG?

A

Normal is less than 120ms (3 small squares) in width

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16
Q

What are the main pathologies associated with the QRS complex?

A

Broad bundle branch block,
Ventricular fibrilation

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17
Q

What are the clinical indications of ST segment elevation?

A

Infarction - MI - no blood flow
Pericarditis

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18
Q

What are the clinical indications of the ST segment depression?

A

Ischaemia - reduced blood flow - angina.

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19
Q

What are the normal features of the T wave in an ECG?

A

Normally should be on the same axis as the QRS complex
However is inverted on V1 and aVR (sometimes also lead 3) especially during deep inspiration.

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20
Q

What can an inverted T wave indicate?

A

Ischemia
Any structural heart problem
Non specific

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21
Q

What are some pathological morpholigies of a T wave?

A

Inverted - ischemia
Flat and Prolonged - low K+
Peaked - high K+ or early MI

22
Q

What are the normal features of the QT interval on an ECG?

A

350-440ms in males
350 -460ms in females.

23
Q

What are some of the consequences of a longer QT interval?

A

More vulnerable to arrythmias.

24
Q

What questions should you ask yourself when reading an ECG?

A

Is the rhythm regular or irregular? (or irregularly regular)
Is the heart rate fast or slow?
Is the axis in lead 1 and 2 positive?
Ratio - is there one p wave to each QRS complex
Is there any ST elevation or depression?
Check intervals (PR, QRS, QT)

25
Q

How do we determine the regularity of an ECG rhythm?

A

Look at the R intervals - determine is these are equally space
If not then determine is there is a pattern to the abnormality - if so indicates an irregularly regular ryhtm.

26
Q

How do we calculate the heart rate from an ECG?

A

For a regular rhythm - 300/no.big squares in RR interval
For an irregular rhythm - number of squares across the ECG sheet multiplied by 6.

27
Q

What is a rough guide for heart rate from an ECG rhythm?

A

One big sqaure between R is a 300bpm
two - 150
three - 100
four - 75
five - 60
6 - 50

28
Q

What are the key features of normal sinus rhythm?

A

Around 75bpm
P waves present in lead 1 and 2
1 p wave to 1 QRS complex
Normal PR interval

29
Q

What are the key features of atrial fibrillation on an ECG?

A

Irregularly irregular QRS complexes
No p-waves
Atrial fibrillation
Wobbly or unstable isoelectric line

30
Q

What are the key features of atrial flutter on an ECG?

A

Regular atrial rhythm
Saw tooth appearance to isoelectric line
may be a 2:1, 3;1 or variable block
Therefore can be an regular irregular or an irregularly irregular rhythm,

31
Q

What does paroxysmal mean on an ECG?

A

Abnormal rhythm appears only time to time
Commonly rhythms change when medication or intervention is given.

32
Q

What is a complete heart block?

A

When the communication between the atria and the ventricles is not functional at all
Both the atria and the ventricles contract but are not in sync with each other
May be a regular rhythm to P and QRS individually but these overall in an irregular way.
Rate tends to be below 35 bpm
Regular QRS complexes

33
Q

What are the features of a ventricual ectopic on an ECG?
Why are these important clinically?

A

A single ectopic beat is normal
A ventricular couplet or triplet tends to be more abnormal.
Feature - premature and broad QRS complex, in the absence of P waves and an the presence of an inverted T wave.

34
Q

What are the features of a left bundle branch block on an ECG?

A

Abnormal QRS complex.
M shape in lateral leads.
W shape in anterior leads V1 (dominant and potentially notched S waves)
M shape in V6 and V5 - lateral leads

35
Q

What are the features of a right bundle block on an ECG?

A

MaRRoW
M complex in V1 - small upward R wave and larger downward s then another large upward R
W complexes in V6 - initial small sonward Q, larger upward R then wide downward S

36
Q

What are the features of a ventricular tachycardia on an ECG?
What are the clinical features of this?

A

Fast - 120 to 250 bpm
Regular
Broad QRS with high amplitude (dominant feature)
No P waves
Potentially life threatening
Usually associated with structural heart disease
Shockable rhythm

37
Q

What is a STEMI?
What is an NSTEMI?

A

STEMI - ST elevation MI - complete and prolonged occlusion of coronary artery
NSTEMI - Non ST elevation MI - severe narrowing or coronary artery or transient occlusion. Causes less extensive damage to the heart.

38
Q

What should you do if a patient presents with chest pain and suspected myocardial cause?

A

Treat as acute coronary artery syndrome
Order diagnostic tests including
1. ECG
2. Trop T markers
3. Consider risk factors
4. Previous cardiac hsitory

39
Q

What are the different stages of the cardiac cycle?

A

Passive ventricular filling
Atrial ejection
Isovolumic ventricular contraction
Ventricular ejection
Isometric ventricular relaxation

revision not new

40
Q

What happens during passive ventricular filling?

A

Isoelectric on ECG
Pressure in ventricles lower than in atria
AV vale open
Ventricules starts to passively fill with blood

41
Q

What happens during atrial ejection?

A

Following P wave
Atria contract
Additional 30% of blood is pushed into ventricles
Aortic and pulmonary semillunar valves close and pressure higher in arteries than ventricles

42
Q

What happens during isovlomic ventricular contraction?

A

Following QRS ventricles start to contract
Tension (pressure) in muscle builds but does not yey shorten
Pressure higher in ventricles than atria so AV vales slam shut (lub)
Pressure not yey high enough to open aortic and pulmonary valves.

43
Q

What happens during ventricular ejection?

A

Pressure in ventricles is now higher than arteries (and aorta)
Aortic and pulmonary vales open but AV valves are closed
Ejection phase

44
Q

What is isovolumetric ventricular relaxation?

A

Following a T wave ventricles start to relax
Pressure falls lower in the ventricles than arteries
Aortic and pulmonary valves slam shut (dub)
But ventricular pressure still higher than atria so AV vales still shut.

45
Q

What leads look at the right ventricle?

A

V1 V2 V3 avR

46
Q

What leads look at the basal septum? (upper interventricular septum)

A

V2 V3 and AvR

47
Q

What leads view the anterior wall of the heart?

A

V2 V3 V4

48
Q

What leads view the lateral wall of the LV?

A

V5 V6

49
Q

What are the common ECG changes seen in a myocardial infarction?

A
50
Q

What are the manifestations of the MI?

A

First few minutes - T wall is tall, pointed and upright with ST segment elevation
After first few hours - T waves invert, R waves voltage decreases and Q waves develop
After a few days - ST segment return to normal but T inversion remains
After weeks or months - T wave may return to upright but the Q wave remains.

Unit 12 (23 decks)

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