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Cardiovascular System Module > Lecture 7 - ECG, Electrical Events In The Heart > Flashcards

Lecture 7 - ECG, Electrical Events In The Heart Flashcards

1
Q

P wave =

A

Atrial depolarisation

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2
Q

P-R (q) interval =

A

Internal between beginning of excitability of atria and ventricles (0-16s)

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3
Q

QRS complex =

A

Ventricular depolarisation, atrial repolarisation occurs but is obscured

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4
Q

Q-T interval

A

Contraction occurring (0.35s)

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5
Q

S-T segment =

A

All ventricle tissue depolarised, contraction occurring

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6
Q

T wave =

A

Ventricular repolarisation

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7
Q

In a healthy individual what is the normal P-R interval in seconds?

A

0.16 seconds

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8
Q

What is the P-R interval important for?

A

Identifies heart conditions if an individuals P-R interval is longer or shorter than 0.16seconds

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9
Q

Why can’t you see atrial repolarisation occurring in the QRS complex?

A

Can’t see on an ECG because it is obscured by ventricular depolarisation

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10
Q

Why is the ST segment a flat line on an ECG?

A

Because there is no change in the electrical currents

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11
Q

What is heart block?

A

Block of electrical signal between the atria and the ventricles usually in the AV node

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12
Q

What are the 3 types of AV heart block?

A

1st degree heart block, 2nd degree and 3rd degree heart block

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13
Q

What is 1st degree heart block?

A

P-R interval is longer at 0.28 seconds, can count how many squares the P-R interval is (40mmseconds per square)

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14
Q

What is second degree heart block?

A

Characterised by a dropped beat, not every p wave is followed by a QRS complex

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15
Q

What is an example of a condition which is classed as second degree heart block?

A

Atrial tachycardia (atrial flutter)

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16
Q

What is second degree heart block free one?

A

Where there is a QRS complex after every 3rd P wave!!

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17
Q

What is 3rd degree heart block?

A

Complete dissociation between the P wave and the QRS complex, complete block of the AV node

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18
Q

What is a condition that is classed as 3rd degree heart block?

A

Severe myocardial ischemia - need a pacemaker

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19
Q

What is the QRS complex like in third degree heart block?

A

It is fairly regular because the AV node set its own rhythm at 40 action potentials per minute, but this is not sufficient if you need to walk or stand up - you would need a pace maker to increase heart rate

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20
Q

What is cardiac arrhythmia?

A

An abnormal heart rate

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21
Q

What is bradycardia?

A

Heart rate slows (under 60 beats per minute)

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22
Q

What is tachycardia?

A

Heart rate is fast - over 100 beats per minute

23
Q

What is ventricular tachycardia?

A

When the ventricles are beating abnormally at 100bpm

24
Q

What are the two varieties that an abnormal heat beat can come In?

A

A regular abnormality or an irregular abnormality

25
Q

What is a regular abnormality?

A

Atrial flutter

26
Q

What is an irregular abnormality?

A

Atrial fibrillation

27
Q

How do abnormalities arise?

A

In the ventricles or supraventricles e.g. the atria or in the AV node

28
Q

Describe atrial fibrillation

A

Irregular a rhythm in the atria, chaotic ventricle activity in the atria - nothing is coordinated

29
Q

What would you not see in atrial fibrillation?

A

A Pave - because the atria is not contracting it is chaotic

30
Q

What are some symptoms of atrial fibrillation?

A

Breathlessness, tiredness and inability to exercise

31
Q

Describe atrial flutter

A

Regular abnormality - one side of the atrium contracts while other relaxes, has a 2:1 or a 3:1 ECG rhythm

32
Q

What are some treatments for atrial flutter?

A

Antiarrythmic drugs or cardioversion therapy (electrical shock)

33
Q

Can you live with ventricular tachyacardia?

A

Yes it is not always life threatening

34
Q

Describe ventricular arrhythmia

A

Abnormally fast heart rate arising at the AV node, additional pathway between the atrium and ventricle, the p wave is not obvious

35
Q

What are the symptoms for ventricular arrhythmia?

A

Chest pain, feel weak, breathlessness or lightheaded, feel tired

36
Q

What is the treatment for ventricular tachycardia?

A

Antiarrhythmic drugs or cardioversion therapy

37
Q

Describe ventricular fibrillation

A

Chaotic ventricular activity, fatal in 1-3 minutes, uncoordinated ventricular contraction = can’t pump blood around the body.
Irregular ECG rhythm, no P wave, broad QRS complex

38
Q

What is the treatment for ventricular fibrillation?

A

Implantable cardioverter defibrillator (ICD)

39
Q

What does the implantable cardioverter fibrillator do?

A

If you heart stops it will defibriallate it and it sets a normal sinus rhythm at 72 beats per minute

40
Q

What is an example of a class I antiarrhythmic drug?

A

Na+ channel blockers

41
Q

What is an example of class II antiarryhtmic drugs?

A

Beta blockers (anti-sympathetic) - they block the beta 1 receptors

42
Q

What do beta blockers affect?

A

The time between each action potential

43
Q

What are class 3 antiarrythmic drugs?

A

K+ channel blockers, affect when there is repolarisation

44
Q

What are class IV antiarryhtmic drugs?

A

Ca2+ channel blockers, affect of the plateau of the action potential, affect whether trigger ca2+ enters for CICR

45
Q

What are class 5 antiarrythmic drugs?

A

Cardiac glycosides

46
Q

How many types of class 1 are there?

A

3 - 1a, 1b, 1c

47
Q

What are class Ia?

A

Moderate blockers, they moderately block the rate of depolarisation which results in an increase of action potentials - used for atrial fibrillation and atrial tachycardia

48
Q

What is an example of class 1a?

A

Quinidine

49
Q

What is class ib?

A

Weak blockers, hardly seen an affect, they shorten the action potentials and can be used for in the ventricles

50
Q

What is an example of Ib?

A

Lidocaine

51
Q

What is class Ic?

A

A strong blocker, only used for life threatening ventricular diseases as you risk blocking the transmission itself in the ventricles.

52
Q

What is an example of class Ic?

A

Flecainide

53
Q

What class is more favourable for treatment?

A

Class III - K+ blockers, as you slow down the rate of repolarisation so you don’t affect the rate of depolarisation so no risk of blocking transmission to the ventricles - you get a slower heart rate

54
Q

What is an example of class III?

A

Amiodarone

Cardiovascular System Module (18 decks)

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