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Cardiovascular > Session 8 > Flashcards

Session 8 Flashcards

1
Q

How many extra cellular recordings do you get with systole?

A

2

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2
Q

What causes an upward going signal on an ECG?

A

Depolarisation moving towards the electrode.

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3
Q

What causes a downward signal on an ECG?

A

Depolarisation moving away from an electrode.

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4
Q

What does repolarisation towards an electrode look like on an ECG?

A

A downward going signal.

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5
Q

What does repolarisation away from an electrode look like on an ECG?

A

An upward going signal.

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6
Q

What does the amplitude of a signal depend on?

A

How much muscle is depolarising

How directly towards the electrode the excitation is moving

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7
Q

On an ECG what causes the P wave?

A

Atrial depolarisation.

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8
Q

On an ECG what causes the Q wave?

A

Septal depolarisation.

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9
Q

On an ECG what causes the R wave?

A

Main ventricular depolarisation.

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10
Q

On an ECG what causes the S wave?

A

The end of ventricular depolarisation.

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11
Q

On an ECG what causes the T wave?

A

Ventricular repolarisation.

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12
Q

Why is the P wave on an ECG small?

A

Because the muscle is small.

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13
Q

How does the action potential spread through the septum?

A

Down and out.

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14
Q

Why is the spread through the ventricles a large upward deflection?

A

Because it spreads quickly.

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15
Q

Why is there a flat line between the S and T wave?

A

Because the ventricles are staying contacted.

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16
Q

What does an ECG measure?

A

A change in electrical field only.

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17
Q

Why is the T wave slower and flatter than the other waves on an ECG?

A

Because each cell repolarises individually so it is slower.

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18
Q

Why do you move the ECG electrodes?

A

It allows detection and isolationist abnormal patterns of electrical activity.

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19
Q

What are amplifiers?

A

They have a positive and negative electrode.

20
Q

How do amplifiers work?

A

They take the signal on the negative input and invert it.
They then add this signal to the positive signal.
They then amplify the total.

Takes direction into account - Think vectors!

21
Q

How many leads are in a full ECG?

A

12

22
Q

What are augmented leads?

A

2 negatives connected and one positive

23
Q

How do augmented leads work?

A

The 2 negative signals are combined and converted to positive.
Combine with actual positive.
Get one view.

24
Q

What are the limb leads?

A

I, II, III

AVR, AVL, AVF

25
Q

How do limb leads view the heart?

A

In a superior to inferior way.

26
Q

What are the chest leads?

A

V1, V2, V3, V4, V5, V6.

27
Q

How do the chest leads view the heart?

A

Anteriorly to posteriorly.

28
Q

What is the standard rate for an ECG?

A

300 squares /min so 0.2 seconds per square.

29
Q

What does it mean if there is no P wave on an ECG?

A

The sick atrial node is not functioning.

30
Q

What happens if the sino atrial node is not functioning?

A

The atrial ventricular node takes over.

31
Q

What is the ability of the atrial ventricular node as a pacemaker?

A

It is relatively irregular so the heart best is also irregular.

32
Q

What does it mean if the P-R interval is prolonged?

A

There is first degree heart block.

33
Q

What does it mean if the P-R interval is irratic?

A

There is second degree heart block.

34
Q

Why is the P-R interval erratic in second degree heart block?

A

Because only some of the action potentials can get through the atrial ventricular node.

35
Q

What is third degree heart block?

A

Where second degree heart block has developed so no action potentials can get through the atrial ventricular node.

36
Q

What can cause extra P waves?

A

There are randomly arranged extra pacemaker cells within the heart that can fire action potentials. This means there are extra P waves which are unrelated to the QRS complex.

37
Q

What can cause a prolonged QRS complex?

A

Damage to the bundle of Hiss causing bundle branch block.

Due to an ectopic site and slow pathway (as action potentials are going back on themselves)

38
Q

What can a NET deflection of 0 mean?

A

That the axis is perpendicular to the lead so cannot be seen.

39
Q

What would the leads pick up in left axis deviation?

A

Lead 1 would be amplified.

Lead 3 will be its opposite.

40
Q

When can left axis deviation occur?

A

In left ventricular hypertrophy - eg aortic stenosis.

41
Q

What would the leads pick up in right axis deviation?

A

Lead 3 would be large.

Lead 1 wold be the negative of itself.

42
Q

What could cause right axis deviation?

A

Right ventricle hypertrophy - eg obstructive lung diseases.

43
Q

What does an S-T depression on an ECG show?

A

It is due to partial occlusion of the coronary arteries so the patient is likely to have angina.

44
Q

What physiological process causes the S-T depression?

A

Thre is a lacks of O2 to the heart so the cells don’t stay depolarised.

45
Q

What does an S-T elevation show?

A

A myocardial infarction.

46
Q

What abnormality will permanently show on an ECG after a myocardial infarction?

A

Pathological Q waves due to the scar tissue not being an,e to conduct the electricity and the signal having to go around.

Cardiovascular (15 decks)

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