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Unit 12 Week 3 > Electrophysiology > Flashcards

Electrophysiology Flashcards

1
Q

Why do an ECG

A
  • evaluate cuase of symptoms (e.g., chest pain)
  • diagnosis of disease
  • arryhtmia analysis
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2
Q

electrocardiogram benefits overview

A

Cheap

Quick

Non-invasive

Fundamental test for every admission

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3
Q

ecg Measures

A

surface manifestations of cardiac electrical activity

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4
Q

positive deflection upwards =

A

Depolarisation TOWARDS ECG lead

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5
Q

negative deflection downwards =

A

Depolarisation AWAY from an ECG lead

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6
Q

how many lead vectors make up an ECG

A

12

  • 3 limb leads
  • 3 “augmented” limb leads work on making a substiutute vector at a right anmgle between the two
  • 6 unipolar precordial (chest) leads
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7
Q

6 limb leads cover which areas:

A
  • 1
  • 2
  • 3
  • AVR
  • AVL
  • AVF
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8
Q

6 chest leads

A

V1

V2

V3

V4

V5

V6

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9
Q

PQRST complex

A
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10
Q

what is the P wave

A

atrial depolarisation

first small bump

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11
Q

PR interval

A

start of P wave to the start of the G downwards deflection

this is the time taken for elecyrical deploarisation to spread from the atria to the ventricles- due to the AVN delay

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12
Q

QRS complex

A

depolarisation of the ventricles

start of Qdownwards deflection to start of T upwards deflection

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13
Q

ST segment

A

enf od S wave (from isoelectric line) to start of T wave upwards deflection

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14
Q

T wave

A

last upwards deflection

ventricular repolarisation

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15
Q

RR interval

A

peak of one R wave to the peak of the next R wave

this is the time between 2 QRS complexes??????

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16
Q

QT INTERVAL

A

beginning of QRS complex (downwards deflection of Q) to the end of the T wave

time for ventricles to depolarise and then repolarise

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17
Q

Normal heart conduction

A

Normal heart conduction starts in the right atria in the Sinoatrial node, depolarisation spreads across the atria causing contraction and ejection of blood out of the atria into the ventricle.

Once the depolarisation reaches the atrioventricular node on the interatrial septum there is a slight delay, allowing time for blood to fully empty the atria and enter the ventricles.

The AVN then sends the wave of depolarisation down the left and right bundle branches towards the purkinje fibres, electrically activating the ventricles and causing simultaneous systole of the ventricles.

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18
Q

how many seconds are 5 small squares on an ecg

A

200 ms/// 0.2s

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19
Q

how long are 5 big boxes

A

1 second

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20
Q

how many small boxes in one big box

A

5

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21
Q

Which leads give an anterior view of the heart

A

V1-V3

22
Q

Which leads give an inferior view of the heart

A

limb leads 2,3 and AVF from the legs

23
Q

Which leads give a lateral view of the heart

A

1, AVL, V5 and V6

24
Q

Pacemamkers of the heart

A

SAN- the dominant pacemaker of the heart with an intrinsic eate of 60-100 bpm- directly affected by extrinsic stimuli

AVN- back up pacemaker intrinsic rate of 40-60 bpm

ventricular myocytes have a rate of 20-45 bpm

25
Q

follow a system when reading an ECG

A
  1. check patient details e.g., on the right patient
  2. rate
  3. rhythm
  4. axis
  5. the alphabet ( P waves, PR interval, QRS complexes ,ST segment, T waves, QT interval)
26
Q

What is a normal heartbeat?

tachycardia?

bradycardia?

A

normal= 60-100

tachycardia> 100 bpm

bradycardia < 60 bpm

27
Q

how many seconds is 1 standard strip?

what do you times this number by to find HR?

A

10 seconds

Rate= total number of R waves x 6

28
Q

how many large squares would there be in 1 minute?

A

1 sec = 25 mm = 5 large squares

1minute= 60 x 5 = 300 large squares

rate = 300 / number of large squares between R waves

29
Q

What characteristics describe a normal sinus rhythm?

A

Normal looking P wave (indicates SAN)

P wave always followed by QRS complex

In a regular fashion

anything not meeting that criteria is not considered normal

30
Q

how do you determine regularity

A

look at the R-R distances

are they regular? regularly irregular? Irregularly irregular?

31
Q

What is the rhythm of this ECG?

A

regular rhythm approx 75 bpm

P waves present

1 P wave per QRS complex

Normal PR interval

Normal sinus rhtyhm

32
Q

name 4 different kind of arrhythmias

A
  1. atrial fibrillation
  2. atrial flutter
  3. heart block (complete, atrioventricular, first degree, second degree, third)
  4. broad complex tachycardia
33
Q

Explain atrial fibrillation

A

Very common arrhythmia, risk increasing with age

multiple wave fronts across the atria cause a sporadic wave form

manifests as an irregular baseline with no clear P waves

because these wave fronts hit the AVN in an irregular fashion, there is irregular electrical action in the ventricles, causing an irregular heartbeat—– irregulalry irregular QRS complex

34
Q

`Explain atrial flutter

A

Affects atria.

Generally, affects 1 macro circuit (one repeating electrical circuit going through the atria). Presents as a sawtooth baseline on the ECG.

Can be regularly irregular or irregularly irregular depending on how long it takes for a wave front to complete a circuit.

Tends to go round the atria at 300bpm, AVN can’t conduct at this pace

so 1:1 hardly ever seen.

2:1 block means that every other flutter is acted on therefore 150 bpm.

3:1 block = 100 bpm

35
Q

Explain complete heart block

A

Where there is absolute failure of the AVN, SAN still operational

Backup, intrinsic pacemaker function of his/ purkinje fibres takes over 30 -40 bpm

Slower and broader PQRS complex

P waves will still be happening at their original rhythm but will now be unrelated to the QRS, P and QRS out of rhythm together.

36
Q

what is atrioventricular block

A

when conduction between the atria and ventricles of the heart is impaired

37
Q

in normal conduction how long is norm al pR intervall

A

less than 0.2 seconds (5 small squares)

38
Q

what is first degree heart block

A

The wife (P wave) is waiting at home. The husband (QRS) comes home late every night, but he always comes home, and it is the same time every night.

(impluse is delayed at AVN, and PR interval is greater than 0.2 secs > 5 small squares)

39
Q

how many kinds of second degree heart block are there and what are they called

A

2

Mobitz1 (wenkebach) and Mobitz 2

40
Q

describe second degree heart block; Mobitz 1/ wenkebach

A

The wife is waiting at home. The husband comes home later and later every night until one night he doesn’t come home at all? (what a wenker!)

Note: the husband must come home at least 2 nights in a row first to see this pattern

(PR interval will become greater and greater until there will be a dropped QRS complex and there are two consecutive P waves, after which the pattern will restart)

can be common in healthy people, like athletes. Just the AVN being under lots of vagal tone

41
Q

Second degree heart block; mobitz 2

A

The wife is waiting at home. Sometimes the husband comes home and sometimes he doesn’t.

When he does come home, it’s always on time.

Note: this unpredictable behaviour is more serious than type 1 second degree heart block and usually requires counselling (pacing).

(P to R and R to R intervals will remain consistent, but there will be “missing” QRS complexes.

42
Q

Explain complete third degree heart block

A

Wife (P wave) is no longer waiting at home. She and her husband (QRS) are on separate schedules and are no longer talking. Each spouse has a regular, individual schedule.

Note: This requires emergency counselling (pacing)

Atrial activity will continue with p waves at one rate. The ventricles (QRS) are depolarising in a slower escape rhythm- both will be regular, but will be uncoordinated)

43
Q

Explain broad complex tachycardia

A

Due to a little bit of scar tissue in the myocardium that causes a mini circuit (usually greater than 180 bpm) in the ventricle.

Because this rate is greater than the SAN, this becomes the dominant pace.

Regular tachycardia, rate ~150 bpm

Broad QRS complexes

No obvious preceding atrial activity

Aka Ventricular tachycardia

44
Q

explain axises on an ecg (Not a focus for year 2)

A

Axis refers to the overall electrical direction within the heart.

Electricity moving towards and electrode is POSITIVE

Electricity moving away from an electrode is NEGATIVE

If there is a change in the overall direction of the energy, the axis will be described as deviated- left, or right

Look at leads I and II

If both are positive, the axis is normal

ECG: left axis

Look at leads I, II and III

If lead 1 is positive, II is midlining/ negative, there is left axis deviation

The deflection are Leaving each other in the Left axis deviation

Right axis:

Look at leads I, II and III

Lead I is more negative, and III is positive, it is right axis deviation

Lead I and lead III are Reaching toward each other in Right axis

45
Q

ST elevation signifies

A

infarction

pericarditis

46
Q

ST depression suggests

A

ischaemia

47
Q

how would low K+ affect a T wave

A

flat anmd prolonged

48
Q

What arrhythmias presents with

regular unco-ordinated P wave and QRS complex

A

complete third degree heart block

49
Q

which arrhythmia presents with

  • an irregular base line with no clear P waves
  • irregulalry regular QRS complex
A

a fib

50
Q

Which arrhythmia presents with

  • Slower and broader PQRS complex
  • P waves will still be happening at their original rhythm
  • 30-40 bp
A

Complete heart block

51
Q

which arrhythmia presents with

  • regular tachycardia at a rate of around 150 bpm
  • broad QRS complexes
A

broad complex tachycardia

52
Q

which arrhythmia presents with

sawtooth baseline

regulalry irregular or irregularly irregular

A

atrial flutter

Unit 12 Week 3 (4 decks)

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