ALS Lecture 12 - The Rhythm of the Heart DONE Flashcards
(99 cards)
1
Q
the electrical system of the heart (4)
A
sinus node, atrio-ventricular node, His-Purkinje system, cardiac myocytes
2
Q
sinus node (2)
A
pacemaker, electrical impulses start here
3
Q
atrio-ventricular node (2)
A
slows down atrial impulse, prevents very high atrial rates transmitted to ventricles
4
Q
His-Purkinje system (2)
A
spreads electrical impulse rapidly, synchronously through left and right
5
Q
cardiac myocytes (2)
A
conduct from H-P system, then contract
6
Q
electrical pathway of heart (6 steps)
A
- impulse begins at SAN
- spread across atria, atria contract
- AVN stimulated, signal delayed
- impulse down bundle of His, goes left and right
- up Purkinje fibres in ventricles
- ventricles contract from base up
7
Q
label the diagram of the electrical pathway of the heart (A)
A
done
8
Q
what drives the rate of sinus node firing? (2)
A
sympathetic NS, parasympathetic NS
9
Q
increased PNS activity does what?
A
bradycardia
10
Q
decreased PNS activity does what?
A
tachycardia
11
Q
examples of increased PNS activity (3)
A
sleep, fainting, fitness
12
Q
examples of decreased PNS activity (4)
A
exercise, blood loss, heart failure, atropine
13
Q
increased SNS activity does what?
A
tachycardia
14
Q
decreased SNS activity does what?
A
bradycardia
15
Q
examples of increased SNS activity (5)
A
exercise after 1st minute, fear, heart failure, adrenaline, salbutamol
16
Q
examples of decreased SNS activity (3)
A
rest and sleep, beta-blockers, fainting
17
Q
P wave
A
atrial depolarisation
18
Q
PR interval
A
time for impulses to go from SAN to AVN
19
Q
PR interval is between
A
start of P wave, start of QRS
20
Q
PR segment
A
conduction from AVN, down bundle of His, up Purkinje fibres
21
Q
QRS complex
A
ventricular depolarisation
22
Q
ST segment
A
ventricles depolarised during plateau of action potential
23
Q
T wave
A
ventricular repolarisation
24
Q
QT interval
A
time between end of ventricular depolarisation and repolarisation
25
U wave
repolarisation of papillary muscles/Purkinje fibres
26
label the diagram of ECG (B)
done
27
normal PR interval
<200msec, <5 small squares
28
normal QRS complex
<110msec, <3 small squares
29
normal QT interval is ___ _____
rate dependent
30
normal QT interval
<460msec, <12 small squares
31
QTc
QT interval corrected for rate
32
QTc =
QT / square root of RR interval in seconds
33
QTc and QT are the same at
60bpm
34
on ECG, one small square =
40msec
35
on ECG, one large square =
200msec
36
one minute is how many large squares?
300
37
to get the heart rate in bpm we
divide 300 by number of large squares between each RR interval
38
if there are 4 large squares between the peaks of QR, what is the heart rate in bpm?
300/4 = 75bpm
39
in normal sinus rhythm, what is the ratio of P wave to QRS?
1:1, P wave in front of every QRS
40
look at the ECG showing normal sinus rhythm (C)
done
41
take a look at ECGpedia (D)
done
42
ectopic pacemaker
excitable cells cause premature heartbeat outside normal SA node function
43
ectopic pacemaker pathophysiology (3 steps)
1. ectopic pacemaker initiates beat, premature contraction
2. does not follow normal signal pathway
3. can make heart refractory or incapable of normal function
44
types of ectopic pacemaker (3)
atrial, junctional, ventricular
45
bradycardia is a heart rate of
60bpm or less
46
a person may have resting bradycardia due to
good fitness
47
bradycardia questions after "are the QRS complexes regular?"
Q. if yes, is there a P-wave in front of each QRS complex with normal AV delay?
- if yes = sinus bradycardia
- if no = heart block
48
bradycardia questions after "are the QRS complexes irregular?"
Q. are there P waves?
- if no = slow AF
- if yes = look at relationship between P waves and QRS
49
look at sinus bradycardia ECG example (E)
done
50
in sinus bradycardia ECG (2)
wide impulse separation, normal impulses
51
what are QRS complexes like in sinus bradycardia?
regular
52
what are P waves like in sinus bradycardia? (2)
P wave before QRS, normal AV delay
53
look at first degree heart block ECG example (F)
done
54
in first degree heart block, the QRS complexes are
regular
55
in first degree heart block, P waves are
before each QRS
56
in first degree heart block PR interval is
prolonged
57
prolonged PR interval shows
delay in conduction from SAN -> AVN
58
2 types of second degree AV block
type 1 - Wenckebach
| type 2 - Mobitz II
59
look at the second degree AV block type 1 (Wenckebach block) ECG example (G)
done
60
what are QRS complexes like in second degree AV block type 1 (Wenckebach block)?
irregular
61
describe complexes 1, 2 and 3 in second degree AV block type 1 (Wenckebach block)
complex 1 - P wave followed by QRS with normal PR interval
complex 2 - P wave with QRS but longer PR interval
complex 3 - PR interval very long, followed by P wave, no QRS
62
second degree AV block type 1 (Wenckebach block) heart block type
3:2, 3 P waves for every 2 QRS
63
look at the second degree AV block type 2 (Mobitz II block) ECG example (H)
done
64
what are QRS intervals like in second degree AV block type 2 (Mobitz II block)?
regular
65
second degree AV block type 2 (Mobitz II block) heart block type
2:1, 2 P waves for every QRS
66
look at third degree AV block (complete heart block) ECG (I)
done
67
what are QRS complexes like in third degree AV block (complete heart block)?
regular
68
what are P waves like in third degree AV block (complete heart block)?
P wave doesn't precede QRS every time, not dependent on each other
69
look at the ECG example of sinus arrest (J)
done
70
sinus arrest is (3)
failure of sinus node to discharge, absence of depolarisation, ventricular asystole
71
look at ECG of brady-tachy syndrome (K)
done
72
Brady-Tachy syndrome
intermittent episodes of slow and fast rates from SA node or atria
73
sinus bradycardia treatment (4)
beta-blockers, calcium channel blockers, digoxin, conservative
74
heart block is caused by
slow/blocked conduction through AV node
75
heart block bradycardia treatment (2)
IV atropine, underlying cause
76
look at the ECG os left and right bundle branch block (L)
done
77
left bundle branch block (2)
assess LV function, bad prognostic
78
right bundle branch block (3)
benign, with lung disease, maybe right ventricle strain
79
tachycardia ECG questions after "are the QRS complexes regular and <120msec wide?"
if yes, supraventricular tachycardia, look for P wave, if <120bpm = sinus tachycardia, if >140bpm SVT
80
tachycardia ECG questions after "are the QRS complexes regular and >120msec wide?"
if yes assume VT
81
tachycardia ECG questions if the QRS complexes are irregular (2)
```
<120msec = AF
>120msec = probs AF, VT if pts ill
```
82
if unsure whether it's SVT or VT (2)
inject adenosine, adenosine blocks AV node so rate should slow if SVT
83
causes of sinus tachycardia (5)
hyperthyroidism, anxiety, heart failure, hypovolaemia, septicaemia
84
stable SVT treatment (3)
IV adenosine, no digoxin, may revert spontaneously
85
stable VT treatment (2)
IV amiodarone, electrical cardioversion, correct hypokalaemia
86
look at ECG of atrial tachycardia (SVT)
done
87
atrial flutter often degenerates to
atrial fibrillation
88
look at the ECGs of atrial flutter (M)
done
89
atrial flutter treatment (3)
anticoagulate, external electrocardioversion, electrophysiological ablasion
90
AF risk increases 4-fold after
stroke
91
in AF, ECG is
irregularly irregular
92
look at the ECGs of rapid ventricular response and controlled ventricular response rate (N)
done
93
atrial fibrillation treatment (3)
rhythm control, ventricular rate control, anti-thrombotic (NOT aspirin)
94
look at the ECG example of ventricular tachycardia (N)
done
95
look at ECG of ventricular fibrillation (O)
done
96
in ventricular fibrillation (4)
rate is 0, no QRS, no pattern, needs defibrillating
97
Torsades de Pointes treatment
magnesium
98
Torsades de Pointes is exacerbated by (2)
low K+, low Mg2+
99
Torsades de Pointes occurs in (2)
drugs, existing bradycardia
