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ALS > 8. Rhythm recognition > Flashcards

8. Rhythm recognition Flashcards

1
Q

ECG electrodes should be placed over BONE/ MUSCLE

A

bone - to minimise artefact

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2
Q

in normal sinus rhythm, depolarisation begins in a group of specialised pacemaker cells called the ___ ___ node, located where?

A

SA node
close to the entry of the SVC in the right atrium

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3
Q

what is the p wave?

A

wave of depolarisation spreading from the SA node through the atrial myocardium

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4
Q

transmission of electrical impulse to the ventricles

1) firstly there is slow conduction through the __ __ node
2) then rapid conduction fo the ventricular myocardium by specialised conducting tissue called ___ ___
3) the ____ ___ ___ carries these fibres from the AV node and then divides into right and left bundle branches in the respective right and left ventricles

A

1) AV
2) purkinje fibres
3) bundle of his

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5
Q

what does the QRS complex represent

A

depolarisation of ventricular myocardium (<0.12s)

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6
Q

between the P and QRS there is a small isoelectric segment which largely represents what?

A

the delay in transmission through the AV node

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7
Q

what does the T wave represent?

A

ventricular repolarisation

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8
Q

standard paper calibration in ECGs? how many squares in 1 second?

A

25mm/s

5 large squares in a second (25 small squares)

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9
Q

estimating HR from ECG?

A

count number of R waves in30 large squares (6s) and multiple by 10

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10
Q

how to tell where an ectopic beat has originated from?

A

narrow QRS (<0.12): atrial muscle or AV node
broad QRS: ventricular muscle or supraventricular with BBB

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11
Q

some ventricular ectopic beats may be accompanied by a P wave occurring shortly after the QRS complex - what causes this?

A

retrograde conduction form the ventricles to the atria

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12
Q

T/F: complete AV block is an escape rhythm

A

true - the cells generating the ventricular rhythm are acting as a pacemaker because no atrial impulses are transmitted to the ventricles

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13
Q

if the QRS complex is less than 3 small squares in width, where does the rhythm originate from?

A

above the bifurcation of the bundle of His - may be the SA node, atria or AV node (but not the ventricular myocardium)

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14
Q

what is the term for when ectopic beats occur alternately with sinus beats for a sustained period?

A

bigeminy

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15
Q

typical rate in atrial flutter?

A

about 300/ min (usually seen best in inferior leads)

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16
Q

sinus P waves are UPRIGHT/ INVERTED in leads II and aVF

A

upright (if inverted, suggests retrograde activate of the AV node ie junctional rhythm or ventricular in origin)

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17
Q

1) shockable
2) non-shockable

cardiac arrest rhythms?

A

1) VF, pVT
2) asystole, PEA

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18
Q

T/F: if the pt is conscious or has a pulse, the rhythm is not VF

A

true

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19
Q

what two rhythm abnomalities may be mistaken for VF?

A

polymorphic VT
pre-excited AF

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20
Q

T/F: there is often little variation in heart rate during a single episode of VT

A

true

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21
Q

what is a capture beat in VT?

A

atrial activity may continue independently of ventricular activity. Occasionally, these atrial beats may be conducted to the ventricles causing capture beats or fusion beats- a single normal looking QRS complex during monomorphic VT

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22
Q

what is a fusion beat in VT?

A

a wave of depolarisation travels down from the AV node simultaneously with a wave of deploarisation travelling up from the ventricular focus producing the arrhythmia- hybrid QRS caused by fusion of the normal and monomorphic QRS complex

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23
Q

in the presence of bundle branch block, an SVT will produce a NARROW/ BROAD complex tachycardia

A

broad
but the safest approach is to regard all broad complex tachycardias as VT until proven otherwise

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24
Q

torsades de pointes is a type of _____ VT, which usually arises in patients with a prolonged ___ ___

A

polymorphic
QT interval (inherited syndromes/ antiarrhythmic drugs/ MI)

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25
Q

treatment of torsades de pointes?

A

IV magnesium and/ or potassium
removal of any predisposing drugs
may require overdrive pacing

26
Q

name an antiarrhythmic drug that can prolong the QT interval

A

amiodarone

27
Q

emergency treatment of most bradycardia is…

A

atropine and/ or cardiac pacing

occasionally isoprenaline or adrenaline

28
Q

what is the PR interval and normal value

A

time between onset of p wave and start of the QRS complex

normally 0.12-0.2s

29
Q

what is first degree AV block

A

when the PR is 0.2s

a common finding

30
Q

causes of 1st degree AV block?

A

physiological e.g. athletes
fibrosis of the conducting system
IHD
structural heart disease
drugs

31
Q

T/F: first degree AV block always requires immediate treatment

A

false - rarely causes symptoms or requires treatment

32
Q

what is described here: when some, but not all, P waves are conducted to the ventricles resulting the absence of

A
33
Q

two types of 2nd degree AV block?

A

Mobitz I (Wenckebach)
Progressive prolongation of PR until a P wave occurs without a QRS complex
Mobitz II
Constant (often prolonged) PR interval in the conducted beats but some of the P waves are not followed by a QRS

34
Q

which type 2 heart block has a higher risk of progression to complex AV block and asystole?

A

Mobitz II

35
Q

what is 3rd degree AV block (CBH)

A

no relationship between P waves and QRS complexes - atrial and ventricular depolarisation arises independently from separate pacemakers

36
Q

1) in complete heart block, if the site of the ‘pacemakers’ stimulating the ventricles if located in the AV node or proximal BoH, this will produce an intrinsic rate of ____
2) if located in the distal Purkinje fibres or ventricular myocardium will produce broad QRS complexes, often with a rate of ____

A

1) 40-50
2) 30-40 (more likely to stop abruptly resulting in asystole)

37
Q

if the normal cardiac pacemaker cells (SA node) fails, the rhythm will be generated more distally and the rate will be FASTER/ SLOWER

A

slower

38
Q

what is a junctional rhythm?

A

where the heartbeat originates from the AV node or His bundle

39
Q

what will normally be slower - a ventricular escape rhythm or a junctional rhythm?

A

ventricular escape rhythm (because the ‘pacemaker’ cells are lower down)

40
Q

what is an idioventricular rhythm?

A

a rhythm arising from the ventricular myocardium

41
Q

what is an accelerated idioventricular rhythm?

A

occurs with a normal HR (usually faster than sinus but not quite VT) - often observed after successful thrombolysis or PCI ‘reperfusion arrhythmiaw

42
Q

what is an agonal rhythm

A

occurs in dying patients - slow, irregular, wide ventricular complexes, often of varying morphology

43
Q

when is a tachyarrhythmia described as supraventricular?

A

when it arises from tissue situated above the bifurcation of the bundle of His

44
Q

T/F: sinus tachycardia is not an arrhythmia

A

true - it represents a response to some other physiological or pathological state e.g. exercise, anxiety, blood loss, fever etc

45
Q

what is the commonest sustained arrhythmia encountered in clinical practice?

A

AF

46
Q

common causes of AF?

A

hypertension, obesity, alcohol excess, structural heart disease

47
Q

in atrial flutter, atrial flutter is seen as flutter waves at a rate of about _____, best seen in the ____ leads

A

300
inferior - ‘saw tooth’ pattern

48
Q

atrial flutter usually arises in the right atrium, so is a recognised complication of diseases that affect the right heart including…

A

COPD
major PE
complex congenital heart disease
CCF

49
Q

2 causes of a broad complex tachycardia

A

1) tachycardia arising in the ventricle below the bifurcation of the bundle of His
2) supraventricular tachycardia conducted aberrantly (right or left bundle branch block)

50
Q

classic ECG feature in WPW? what is this caused by?

A

they have accessory pathways connecting atrial and ventricular myocardium
some conduction occurs through these pathways as well as through the AV node - resulting in pre-excitation

> > widens the QRS complex by delta waves

51
Q

QT prolongation predisposes people to which arrhythmias in particular?

A

TdP
VF

52
Q

what is the QT interval measured as?

A

start of the QRS complex to the end of the T wave

53
Q

which lead usually allows the best measurement of the QT interval?

A

lead II

54
Q

the QT interval is usually slightly SHORTER/ LONGER in the presence of bundle branch block

A

longer

55
Q

the QT interval SHORTENS/ LENGTHENS as the heart rate increases

A

shortens
(the QTc corrects for this)

56
Q

normal QTc in men and women?

A

up to 0.45s in women and 0.43s in men

57
Q

a QTc of ___s or more indicates a high risk of cardiac arrest and sudden death

A

0.5s

58
Q

causes of
1) shortened QT interval
2) prolonged QT interval

A

1) hypercalcaemia, digoxin treatment
2) hypokalaemia, hypomagnesaemia, hypocalcaemia, hypothermia, myocarditis, MI, drugs

59
Q

6 stage system to analyse an ECG rhythm?

A

1) is there electrical activity
2) what is the QRS rate
3) QRS regular or irregular
4) QRS wide or narrow
5) if atrial activity present
6) is atrial activity related to ventricular activity- how so

60
Q

look at pages 112-113 for rhythm strip recognition

A

ok

ALS (15 decks)

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