Mechanism of Arrythmias - Quiz 2 Flashcards
(79 cards)
1
Q
three mechanisms of arrhythmia
A
- abnormal automaticity
- abnormal triggered activity
- re-entry
2
Q
types of abnormal triggered activity
A
- early afterdepolarizations
- late afterdepolarizations
3
Q
abnormal automaticity due to
A
- abnormal phase 4 depolarization
4
Q
exclusivity of mechanisms of arrhythmia
A
- not mutually exclusive
5
Q
abnormal phase 4 depolarization due to which conditions
A
- degeneration/fibrosis
- ischemia
- stretch
- hypokalemia
- sympathetic stimulation
DISH S
6
Q
stretch due to
A
- people with CHF
7
Q
EAD inciters
A
- QT prolonging drugs
8
Q
EADs exaggerated by
A
- slow heart rate
- hypokalemia
9
Q
EADs blunted by
A
- rapid heart rates
- K+, Mg2+
10
Q
EADs mechanisms
A
- net increase inward
- plateau current
11
Q
EADs putative clinical rhythm
A
- torsades
12
Q
A
early afterdepolarizations
13
Q
A
delayed afterdepolarizations
14
Q
DADs inciters
A
- digitalis
- catecholamines
15
Q
DADs exaggerated by
A
- rapid rates
16
Q
DADs blunted by
A
- Ca2+ channel block
17
Q
DADs mechanism
A
- intracellular Ca2+ overload
18
Q
DADs putative clinical rhythm
A
- dig tox
- ischemia
- outflow tract VT
19
Q
most common mechanism for abnormal rhythms
A
- reentry
20
Q
what will favor re-rentry
A
2 heterogenous pathways
Transient or permanent unidirectional block
dispersion of refractoriness
slow conduction velocity in the normal unblocked pathway
21
Q
what can result from a transient or unidirectional block
A
one electrical pathway has either a prolonged refractory period or a prolonged repolarization time
producing a wave which only travels down the remaining pathway.
22
Q
importance of slow conduction in regions of less refractoriness
A
must be slow enough relative to the refractoriness of the blocked pathway to allow recovery of the previously blocked pathway.
23
Q
WPW AV rentry tachycardia structural physiology
A
- AV bypass tracts found along muscular portion of mitral and tricuspid annulus’
- THESE ARE THE ACCESSORY TRACTS
24
Q
WPW sinus rhythm due to
A
- fusion of bypass and AV nodal conduction to ventricle
25
WPW re-entry tachycardia due to
- there is a block in the bypass tract
- re-entry of impulse from AV node over bypass tract that now depolarizes backwards
26
how can an accessory tract depolarize again?
- the slow conduction of the AV node allows the bypass tract to recover its excitability
27
premature impulse in AV re-entry tachycardia due to
- unidrectional block in the bypass tract only
28
where would you see this signal?
AV re-entry tachycardia
in WPW
29
strategy of antiarrhythmic agents
- alter automaticity
- alter conduction velocity
- alter refractory period
30
antiarrythmic drugs - how we alter automaticity
ALL WAYS TO SLOW DOWN HEART RATE
- decrease slope of phase 4 depolarization
- increase threshold potential
- decrease resting membrane potential
31
antiarrythmic drugs - ways to alter conduction velocity
- decrease rate of rise of phase 0
- decrease resting membrane potenail and responsiveness
32
antiarrythmic drugs - ways to alter refractory period
- increase phase 2 plateau
- increase phase 3 repolarization
- increase action potenial duration
33
strategy of catheter ablation
- eliminate pathway of reentry circuit
- create barrier of conduction to disrupt reentry circuit
- eliminate source of abnormal automaticity or triggered activity
34
bradyarrythmias defined as
- heart rate less than 60 bpm
35
bradyarrythmias due to
- abnormal automaticity
- degeneration of the normal conduction system
36
diagnosis based on EKG
- sinus bradycardia
37
p wave in sinus bradycardia
- normal p wave
38
conditions that can cause sinus bradycardia
- high vagal tone
- ischemia
- degenerative disease
- drugs
- hypothyroidism
HDIDH
39
treatment of sinus bradycardia
- no treatment unless symptomatic
- then pacemaker
40
diagnosis based on EKG
- sinus pause
41
sinus pause cause
- degenerative disease in or around SA node
42
sinus pause treatment
- pacemaker if symptomatic
43
symptoms of sinus pause
- syncope generally greater than 3 seconds
44
diagnosis based on EKG
- tachy-brady syndrome
45
what you see in tachy-brady syndrome
due to
- pauses occur at termination of tachyarrythmias
- due to overdrive suppression of SA node
46
diagnosis based on EKG
- junctional escape rhythm
47
junctional escape rhythm due to
- AV nodal cells acting as subsidiary pacemaker due to slower phase 4 depolarization
48
hallmark of junctional escape rhythm
- no P before QRS
49
what you see in first degree heart block
- every P makes a QRS
- but long PR
50
what you see in second degree heart block
- regular P waves
- some but not all P waves makes QRS complexes
51
what you see in third degree heart blocks
- constant and independent atrial and ventricular rates
- no P conducts to a QRS
52
diagnosis based off EKG
- 1st degree AV block
53
causes of first degree AV block
- high vagal tone
- degenerative disease
- drugs
54
treatment of first degree AV block
- nothing
55
which secondary AV block is most common
- mobitz 1
56
refractoriness of mobitz 1
varies
57
PR of mobitz 1
long, prolongs
58
usual site of block mobitz 1
- within AV node
59
QRS duration mobitz 1
- any
60
causes mobitz 1
- AV nodal blocking drugs
- inferior MI
- vagal tone
- degenerative disease
61
carotid massage mobitz 1
- worsens
62
exercise mobitz 1
- improves
63
permanent pacing (mobitz 1)
- not usually
64
refractoriness of mobitz 2
- fixed
65
PR of mobitz 2
- short, constant
66
usual site of block mobitz 2
- below the AV node
67
QRS duration mobitz 2
- usually wide
- usually associted with BBB
68
causes of mobitz 2
- Na+ channel blocking drugs
- anterior MI
- degenerative disease
69
carotid massage mobitz 2
- no change or improves
70
exercise, atropine mobitz 2
- no change or worsens
71
permanent pacing for mobitz 2
- yes
72
diagnosis based on EKG
- mobitz 1 block
- look for P without QRS
- wide QRS
- longer PR
73
diagnosis based on EKG
mobitz II
- look for P without QRS then short PR
74
diagnosis based on EKG
- 3rd degree AV block
- no relationship between P and QRS
- more P's than QRS's. QRS's are regular
75
treatment of 3rd degree AV block
- reverse with treatment of underlying cause
- may need pacemaker
76
cause of 3rd degree AV block
- ischemia/infarct
- degenerative disease
77
diagnosis based on EKG
3rd degree AV block
- due to inferior MI
78
diagnosis based on EKG
- sinus bradycardia - atrial pacing
- pacemaker spike followed by P wave
79
diagnosis based on EKG
- ventricular pacing
- can see the spike of the current depolarizing the ventricle
