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Unit 4 > w3: ECG practical > Flashcards

w3: ECG practical Flashcards

1
Q

Draw an ECG and highlight the different segments and intervals.

A
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2
Q

What is an ECG useful at detecting?

A

An enlarged left ventricles
Ventricle arrhythmias
Evidence of a prior, ongoing or upcoming myocardial infarction
Impairment of blood flow to the heart
Abnormal blood electrolytes
Cardiac inflammation or pericarditis

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3
Q

What is the heart beat of a person with tachycardia?

A

More than 100bpm

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4
Q

What s=is the heart rate of a patient with bradycardia?

A

Less than 60bpm

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5
Q

What is atrial flutter an example of?

A

Atrial tachycardia.
P wave is bumpy.

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6
Q

What are some features of ventricular tachycardia?

A

Results in abnormal QRS complexes
May result in ventricular fibrilation.

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7
Q

WHat are some features of premature supraventricular contractions?

A

When the atria contract early, triggered by something that is not the SAN.
Results in an irregular peripheral pulse in rate and volume.

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8
Q

What length on a ECG might indicate an AV block for the PR interval?

A

Larger than 5 small squares.

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9
Q

What are the featues of a first degree AV block?

A

Every atrial depolarisation is conducted to the ventricles.
However there is a delay between the P wave and the QRS complex so the PR interval is longer than five small squares, but this is consistent and always followed by a QRS complex.

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10
Q

What are the features of a 2nd degree AV block?

A

Only some strail depolarisations are passed onto the ventricles.
PR intervals
Longer longer longer drop - that is a wenkebach
Mobitz two- PR interval is too long but constant, then a beat is dropped.

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11
Q

What are the features of a 3rd degree AV block?

A

Atria and ventricles contract independetly of each other.
The P to P is constant, the Q to Q is constant.
Atrial depolarisation is not passed onto the ventricles.
P QRS and T waves may overlap giving a weird shape.
All bradycardia.

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12
Q

What is a feature of all AV blocks?

A

Bradycardia.

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13
Q

What makes up a 12 lead ECG?

A

6 chest electrodes
3 standard limb leads.
3 augmented limb leads.
Limb leads have a total of 4 electrodes

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14
Q

What is the difference between a bipolar and unipolar lead?

A

Bipolar lead uses two electrodes on the skin, one acts as a positive electrode and the other as a negative electrode.
A unipolar lead only has one electrode, movement towards the electrode is counted as positive, a combination of other electrodes are used as the negative.

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15
Q

Where are limb leads commonly placed?

A

ON on the right arm, left arm and left leg.
Often a lead is placed on the right leg to act as earth.

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16
Q

What does einthovens triangle show about limb leads?

A

Shows the location of three electrodes (RA, LA and LF).
Leads are numbered anticlockwise
Makes bipolar leads
Right arm always acts as the negative electrode
Left foot always acts as the positive elctrode.

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17
Q

What is the deal with augemented limb leads?

A

Added onto Einthovens triangle.
Are unipolar leads
aVR - right arm is positive electrode
aVF left foot is the positive electrode
aVL left arm is the positive electrode.
The other two leads combine to make the negative electrode.

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18
Q

What are precordial leads?

A

Six leads.
Perpendicular to limb and augumented leads, located on anterior to lateral chest wall.
Lead 1 in the middle of the chest, leads 6 on the mid axillary lines.
These are also known as unipolar chest leads and annotated at v1 to v6
v etc acts at the positive electrode whilst a combination of the augmented leads acts as the negative electrode.

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19
Q

What are the angle of limb leads and augmented leads?

A

Lead 1 is the main lead, given an angle of 0 degrees, moving anticlockwse gives a negative angle, moving positive gives a positive angle.
Hence lead 2 is 60 degrees
aVF is 90 degrees
lead 3 is 120 degrees
avR is -150 degrees
avL is -30 degrees.

20
Q

Where are the different chest leads placed?

A

v1 - parasternal right 4th ICS
v2 - paraseternal left 4th ICS
v3 - left midway between v2 and v4
v4 - left 5 ICS on the midclavicular line
v5 - same horixontal level as v4 but on the anterior axillary line
v6 - same horizontal level as V4 but on the mid axilarry line.

21
Q

What does arrythmias describe?

A

Heart beats that are too fast, too slow or irregular.

22
Q

What often causes premeture contractions?
How does the patient present?

A

Generally caused by excessive alcohol, smoking or caffeine or stress. Are not a serious heart disease.
After the premature contraction there is often a pause in contraction then a larger than normal beat, this means the patient feels as if they are having heart palpitations.

23
Q

What are the features of a sinus arrhythmia?

A

Overall heart rate is normal, increases during inspiration and decreases during expiration.

24
Q

What is sinus tachycardia?

A

The sinus node is firing at a higher than normal rate.

25
Q

What is paroxymal atrial tachycardia?

A

When parts of the atria not normally involved in electrical conductivity cause to atria to contract before the next SAN firing is due. Causes unusual timing of ventricular contraction
Periods of very fast heart rates, appear and then disappear.
Also known as supraventricular tachycardia.

26
Q

What is atrial flutter?

A

The atrium contract rapidly but at a constant rate.

27
Q

What is atrial fibrilation?

A

The atrial tissue depolarisation is not coordinated, so the atria o longer contract effectively.
Contraction in the ventricles is also irregular depending on what activity is passed onto the AV node.
P wave is absent

28
Q

What is a preamture nodal contraction?

A

When an nodal eptopic focus fires before the next SAN firing is due.

29
Q

What are premature ventricular complexes?

A

A section of ventricle tisue depolarisses spontaneously causing the ventricle to contract prematurely, this is often followed by a pause in activity to compensate.
Very common in teenagers with no pathological concerns.

30
Q

What is ventricular fibrillation?

A

No coordination to ventricular depolarisation and contraction of tissue, the heart ceases to eject blood.

31
Q

What is ventricular tachycardia?

A

Ventricular ecotopic foci cause rapid depolarisation

32
Q

What is a bundle branch block?

A

When electrical activity in one of the right of left bundles branches is impaired, results in widened QRS complexes.

33
Q

What does angina look like on an ECG?

A

Depression of ST interval
May have inversed T wave

34
Q

What are some features of a myocardial infarction on an ECG?

A

Excagerated ST intervals, either depression or elevation depending on the lead used.
As the tissue dies T waves becomes inverted and the Q complexes lengthen.

35
Q

What is the purpose of an ECG?

A

Records the overall vector of electrical activity in the heart at any one time and converted this to a deflection of a line on an ECG tracing.

36
Q

How should you apply an ECG to a patient?

A

Ask for consent.
Explain the procedure to them, highlighting it is not invasive, measures the electrical activity of the heart, explain that they will need to lift up their t-shirt, suggest they bring a chaperone.
Use new clean leads (or wipe clean)
Remove jewerlly from the patients arms and gently wipe the area to hold the ECG with alcohol ipes and allow to dry.
Take the ECG, reassure the patient to remain relaxed and to not move their limbs, reassure them that the ECG will take a few minutes to be collected and not to worry about the delay.

37
Q

What are the different sections of depolarisation in a QRS complex?

A

Q depolarisation from the left to right bundle branch
R depolarisation of the Purkinje fibres
S depolarisation of the tissue around the AV ring.

38
Q

What are the average timing on an ECG?

A

Each mini sqaure = 0.04 seconds
P wave = under 5 mini squares
PR interval = 4 to 5 mini sqaures
QRS complex - less than 3 mini sqaures
T wave = 3 to 5 small sqaures.
QT interval = 10 mini sqaures

39
Q

What is the relationship between the ECG QRS complex and a pulse wave?

A

The QRS complex occurs first then their is a delay before the rising limb of the pulse wave.
This delay is due to the time it takes for the electrical activity (action potential) to generate a contraction, then the delay as this increase in pressure travels from the heart to the finger periphery.

40
Q

In relation to an ECG where abouts would the dicrotic notch in pulse pressure be located?

A

After the T waves (ventricles relax and aortic valve shuts).

41
Q

What is the relationship between heart rate and ventilation?

A

During inspiration the heart rate increase - decrease in blood pressure, less Vr to left ventricle
During expiration the heart rate decreases - increase in blood pressure as increased VR to the left ventricle
https://www.youtube.com/watch?v=rXZxDma9s5s

42
Q

What is the cardiac axis?

A

THe mean electrical vector or QRS vector during ventricular depolarisation.

43
Q

What is the normal cardiac axis and how is it determined?

A

Between +30 and -90 degrees
Calculate the net QRS defelction for lead 1
Calculate the net QRS delfection for lead avF
Plot on hexaxial graph
Join up dots to create a vector.

44
Q

What are the different quadrants of the heart that the cardiac axis can be in?

A

Normal between -30 and +90
Left deviation between -30 and -90
Right axis deviation between 90 and 180
Intermediate between 180 and -90.

45
Q

What direction do perkinji fibres run in?

A

From endocardium to epicardium.

46
Q

What does R’ indicate in an ECG?

A

A second R deflection (normally after a completed QRS complex).

47
Q

When does a vector produce a straight line on an ECG?

A

Known as an isoelectric line either there is no vector or the vector is travelling perpendicular to the lead.

Unit 4 (17 decks)

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