Rhythm Recognition Flashcards

1
Q

What are the sites for defib pads

A

beneath the right clavicle
left mid-axillary line

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2
Q

What is the difference in voltage in myocardial cells and extracellular space?

A

90mV

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3
Q

What triggers depolarisation and contraction?

A

Ion shift

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4
Q

In normal sinus rhythm where does depolarisation begin?

A

the pacemaker cells (SA node)

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5
Q

What is the first wave in the ECG?

A

P wave

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6
Q

What does the P wave represent?

A

depolarisation spreading from the SA node through the atrial myocardium

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7
Q

What happens after the P wave

A

slow conduction through the AV node, followed by rapid conduction to the ventricular myocardium

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8
Q

What conducts through the ventricular myocardium?

A

Purkinje fibres

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9
Q

What carries Purkinje fibres?

A

Bundle of His

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10
Q

What does the QRS complex represent?

A

depolarisation of the ventricular myocardium

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11
Q

What does the segment between the P and QRS complex represent?

A

Isoelectric segment- delay in transmission in the AV node

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12
Q

What does the T wave represent?

A

recovery of the resting potential in the cells of the conducting system and ventricular myocardium

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13
Q

What is happening in bundle branch block?

A

One of the segments of the bundle of His is diseased or damaged and so conduction is carried much more rapidly through the other division and then more slowly through the ventricular myocardium

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14
Q

What happens to the QRS in bundle branch block?

A

broadened- because depolarisation of both ventricles takes longer

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15
Q

What is the 6 stage system to analyse an ECG?

A
  1. Is there electrical activity
  2. What is the QRS rate
  3. Is the QRS rhythm irregular/regular
  4. Is the QRS complex width normal?
  5. is atrial activity present
  6. is atrial activity related to ventricular activity
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16
Q

What is happening in VF?

A

All coordination of electrical activity is lost
- no effective ventricular contraction and no detectable cardiac output

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17
Q

What is PEA

A

There are complexes on the ECG that would be expected to produce a pulse but there isn’t one

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18
Q

What is a normal ventricular rate?

A

60-100

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19
Q

What represents one second on an ECG?

If calibrated to 25mms

A

5 large squares

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20
Q

How should you estimate ventricular rate?

A

Count the cardiac cycles in 30 large squares (6 seconds) and multiply it by 10

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21
Q

If the rhythm is irregular what needs to be decided?

A
  1. is it totally irregular
  2. is the basic rhythm regular with intermittent irregularity
  3. is there a recurring cyclical variation in the R-R intervals?
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22
Q

If the QRS complex of an ectopic is narrow where has it likely originated from?

A

The atria

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23
Q

What might broad complex ectopics represent?

A

Ventricular origin or ectopics with BBB

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24
Q

What is a premature beat?

A

Ectopic beats that occur early

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25
Q

What is an escape beat?

A

A beat that arises from the AV node of from the ventricular myocardium after a long pause

for example during sinus brady or after sinus arrest

this implies that the focus in the AV node or ventricle that generates this beat is acting as a back-up pacemaker because the function of the SA node is too slow or absent

26
Q

What is complete AV block?

A

Escape rhythm in which the cells generating the ventricular rhythm are acting as a pacemaker because no atrial impulses are being transmitted to the ventricules

27
Q

How many ectopics in quick succession need to occur to be classified as a tachyarrhythmia?

A

more than 3 in succession

28
Q

What is bigeminy?

A

When ectopic beats are occuring alternately with sinus beats for a prolonged period?

29
Q

What is the upper limit for the QRS?

A

3 small squares 0.12s

30
Q

What does saw-tooth P waves suggest?

A

Atrial flutter

31
Q
A
32
Q

In sustained tachycardia where P waves cannot be seen what may be done?

A

Vagal stimulation (trainsiently increasing AV block) or adenosine

33
Q

If retrograde activation of the atria is happening from the AV node what will you be able to see in P waves?

A

Inversion in II and aVF because atrial depolarisation is happening in the wrong direction

34
Q

What are the causes of atrioventricular dissasociation?

A
  • complete (third degree) AV block
  • some examples of VT
35
Q

If VF is present and the patient is conscious and has a pulse what should be done?

A

If it has been more than a few seconds, rhythm isn’t VF check again

36
Q

What rhythms may resemble VF?

A

pVT , pre-excited AF

37
Q

When can pre-excited AF occur?

A

In the presence of an accessory pathway connecting atrial and ventricular muscle in the WPW syndrome

38
Q

What confirms the rhythm as VT?

A

the identification of P waves dissociated from the QRS during a broad complex tachycardia

39
Q

In the presence of BBB what with a SVT produce?

A

A broad complex tachycardia

40
Q

In which patients does TDP usually occur?

A

Patients with a prolonged Qt interval

41
Q

What should be avoided in TDP?

A

Amiodarone

42
Q

What is a bradyarrhythmia

A

ventricular rate less than 60

43
Q

What can cause pathological bradycardia?

A

malfunction of the SA node or from partial/complete failure of atrioventricular conduction

44
Q

What is first degree AV block?

A

PR interval >0.2 s and is a common finding

45
Q

What does first degree AV block represent?

A

Delay in conduction through the AV junction

46
Q

What are the causes of AV block?

A

physiological (Athletes)
fibrosis of the conducting system
structural heart disease
IHD
drugs

47
Q

What is second degree AV block?

A

Some, not all P waves are conducted to ventricles

48
Q

What are the types of second degree AV block?

A
  • mobitz I
  • mobitz II
  • 2:1 and 3:1
49
Q

What is Mobitz I AV block?

A
  • PR interval shows progressive prolongation after each successive p wave until a P wave occurs without a QRS
50
Q

What is mobitz II ?

A

Constant prolonged PR interval but some of the p waves are not conducted

these patients have an increased risk of complete AV block and asystole

51
Q

What is complete heart block?

A

No relationship between P waves and QRS complexes

52
Q

What is an agonal rhythm?

A

Occurs in dying patients
Slow, irregular, wide complexes often varying morphology
Doesn’t usually generate a pulse

53
Q

What is atrial flutter often caused by?

A

Disease that affects the right heart
-COPD
-PE
-CHF

54
Q

What does prolonged QT predispose to?

A

ventricular arrythmia
- tdp
- vf

55
Q

Which is the best lead for measuring QT?

A

Lead III

56
Q

What is the normal QTc?

A
  • 0.43 in women
  • 0.45 men
57
Q

What does a QTc of >0.5 suggest

A

high risk of sudden cardiac death

58
Q

what may cause a shortened QTc

A
  • hypercalcaemia
  • digoxin
59
Q

What are some causes of prolonged QTc?

A
  • hypokalaemia
  • hypomagnesaemia
  • hypocalcaemia
  • hypothermia
  • myocarditis
60
Q
A