Arrhythmia - Therapy Flashcards
1
Q
What is arrhythmia?
A
A deviation from the ‘normal’ rhythm of the heart
2
Q
What is a deviation from the normal rhythm of the heart called?
A
Arrhythmia
3
Q
What are examples of arrhythmias?
A
Sinus arrhythmia
Tachycardias
Bradycardias (heart block)
4
Q
What are examples of tachycardias?
A
Supraventricular arrhythmia (atrial fibrillation and supraventricular tachycardia)
Ventricular arrhythmia (ventricular tachycardia and ventricular fibrillation)
5
Q
What does STC stand for?
A
Supraventricular tachycardia
6
Q
What are examples of supraventricular arrhythmias?
A
Atrial fibrillation
Supraventricular tachycardia
7
Q
What are examples of ventricular arrhythmias?
A
Ventricular tachycardia
Ventricular fibrillation
8
Q
What are bradycardias also known as?
A
Heart block
9
Q
What does the P wave of the ECG correspond to?
A
Activation of the atria
10
Q
What does the QRS complex of the ECG correspond to?
A
Activation of the ventricles
11
Q
What does the T wave of the ECG correspond to?
A
Recovery wave
12
Q
What is the charge inside a cell relative to the outside?
A
Negative
13
Q
What is the charge inside a cell at rest known as?
A
Resting membrane potential
14
Q
Why is the resting membrane potential of a cell negative?
A
Uneven distribution of ions across the cell membrane
Dependent on the sodium-potassium ATPase pump (needs energy)
15
Q
Talk about the concentration gradients of potassium, sodium and calcium inside and outside a myocyte?
A
Potassium greater concentration inside the cell
Calcium and sodium greater concentration outside the cell
16
Q
What is used to classify antiarrhythmias?
A
Vaughan-Williams classification
17
Q
What are the different classifications of antiarrhythmics?
A
IA
IB
IC
II
III
IV
V
18
Q
What are class I antiarrhythmias?
A
Membrane stabilising agents
19
Q
How do class I antiarrhythmias work?
A
Acts on fast sodium channel responsible for phase 0
Decreases the amplitude size (size of action potential)
Reduces velocity of conduction/excitability
20
Q
What are the different categories of class I antiarrhythmias?
A
Ia
Ib
Ic
21
Q
How do class IA, IB and IC vary in effect?
A
Different effect on action potential duration and therefore effective refractory period
22
Q
What is an example of a class IA antiarrhythmias?
A
Quinidine
23
Q
How does a class Ia antiarrhythmias work?
A
Moderate sodium channel blockade
24
Q
How does a class I antiarrhythmias affect the effective refractory period?
A
Increases it
25
What is an example of a class IB antiarrhythmias?
Lidocaine
26
How do class IB antiarrhythmias work?
Weak sodium channel blockade
27
How do class IB antiarrhythmias affect the effective refractory period?
Decrease effective refractory period
28
What does ERP stand for?
Effect refractory period
29
What is an example of a class IC antiarrhythmias?
Flecainide
30
How do class IC antiarrhythmias work?
Strong sodium channel blockade
31
How do class IC antiarrhythmias affect the effective refractory period?
Do not change effective refractory period
32
What class I antiarrhythmias is the most common?
IC (flecainide)
33
When are class I antiarrhythmias most effective?
At high heart rates
34
If the graph represented class I antiarrhythmias, what would be IA, IB and IC?
1 - class IC
2 - class IB
3 - class IA
35
What are class II antiarrhythmias?
Beta blockers
36
What are examples of class II antiarrhythmias?
Atenolol
Bisoprolol
Propranolol
37
How do class II antiarrhythmias work?
Acts via B1 receptors to block sympathetic stimulation of the heart:
Prolongs phase 4 depolarisation
Shortens phase 2
38
How do class II antiarrhythmias prolong phase 4 depolarisation?
Slows SA discharge and AV conduction
Reduces excitability in non-nodial cardiac tissue
39
What does class II antiarrhythmias shortening phase 2 mean for contractility?
Negative effect on contractility
40
What are class II antiarrhythmias the first line for?
Atrial fibrillation (bisoprolol)
41
What is the first line for atrial fibrillation?
Class II antiarrhythmias (bisoprolol)
42
How do class III antiarrhythmias work?
Prolong refractiveness (slows K flow out of cells):
Increase action potential duration
Prolong repolarisation in phase 3
Prolongs effective refractory period
43
What are examples of class III antiarrhythmias?
Amiodarone
Bretylium
Sotalol
44
How do class III antiarrhythmias prolong refractiveness?
Slows K flow out of cells
45
What is amiodarone used for?
Ventricular tachycardia and occasionally in supraventricular tachycardia
46
What are problems with amiodarone?
Many interactions with other drugs (particular digoxin)
Striking side effects (thyroid, pulmonary fibrosis, slate, corneal deposits)
47
What is slate?
Grey pigmentation
48
What is grey pigmentation called?
Slate
49
How do class III antiarrhythmias increase the action potential duration?
Prolong repolarisation in phase 3
Prolongs effective refractory period
50
What effect do class III antiarrhythmias have on the effective refractory period?
Prolongs effective refractory period
51
What are class III antiarrhythmias used for?
Dysrhythmias that are difficult to treat
Life threatening ventricular tachycardia or fibrillation
Atrial fibrillation or flutter
52
What are class IV antiarrhythmias?
Calcium channel blockers
53
What are examples of class IV antiarrhythmias?
Verapamil
Diltiazem
54
How do class IV antiarrhythmias work?
Bind to Lcard type voltage gated calcium channels
Depress phase 4 depolarisation in SA and AV nodes (slowing heart rate)
Shortens phase 2 plateau phase
55
What effect does class IV antiarrhythmias shortening phase have on contractility?
Decrease contractility
56
When are class IV antiarrhythmias most effective?
At high heart rates
57
What are class IV antiarrhythmias used for?
Paraoxysmal supraventricular tachycardia
Rate control for atrial fibrillation and flutter
58
What are class V antiarrhythmias?
Others (do not fit into other categories, have properties of many different classes)
59
What are examples of class V antiarrhythmias?
Digoxin
Adenosine
60
What is digoxin?
Cardiac glycoside (increases output force of the heart and increases rate of contractions)
61
What effect does digoxin have on the heart?
Increases output force and increases rate of contractions
Increases vagal tone
Complex effect on cardiac action potential
Increases [Ca2+]
62
How does digoxin work?
Inhibits cellular sodium-potassium ATPase pump
63
What effect does digoxin increase vagal tone have?
Slows SA/AV node conduction
64
How does digoxin affect the cardiac action potential?
Reduces refractory period in myocardium
65
What is the half life of digoxin?
36-48 hours
66
What can be said about excretion of digoxin?
50-70% excreted almost entirely unchanged by kidneys
Excretion proportional to glomular filtration rate
67
What does GFR stand for?
Glomular filtration rate
68
What needs to be monitored when using digoxin?
Potassium levels
[digoxin]plasma
Toxicity
69
What is digoxin used for (indications for it)?
Atrial dysrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia)
Heart failure
70
What does AF stand for?
Atrial fibrillation
71
What are examples of digoxin toxicity?
Nausea and vomiting
Xanthopsia
Bradycardia
Tachycardia
Arrhythmias (ventricular tachycardia and ventricular fibrillation)
72
What is xanthopsia?
Colour vision deficiency in which there is a prominance of yellow
73
What is a colour deficiency in which there is a predominance of yellow?
Xanthopsia
74
What are signs of dixogin toxicity?
Reverse tick appearance of ST segment in lateral leads
75
What is the treatment for digoxin toxicity?
Stop digoxin
If levels are very high adn risk of significant arrhythmias give digibind
76
What is digibind?
Digoxin immune antibody
Binds with digoxin forming complex molecules
Excreted in the urine
77
What makes digoxin toxicity more serious?
Low potassium levels
78
How does adenosine work?
Slows/blocks conduction through the AV node
79
What is adenosine used for?
Converting paroxysmal supraventricular tachycardia to sinus rhythm
80
What is the only way that adenosine can be administered?
As fast IV push
81
What is a possible side effect of adenosine?
May cause asystole for a few seconds
82
What is the half life of adenosine like?
Very short
83
What is sinus rhythm?
Any cardiac rhythm in which depolarisation of the cardiac muscle beings at the sinus node
84
What is any cardiac rhythm in which depolarisation of the cardiac muscle begins at the sinus node called?
Sinus rhythm
85
What side effect can all antiarrhythmias cause?
Arrhythmia
86
Other than antiarrhytmias, what else may be given?
Anticoagulants
87
What are indications for anticoagulation?
Atrial fibrillation
Metallic heart valves
Deep vein thrombosis
Pulmonary embolism
88
Why is atrial fibrillation an indication for anticoagulation?
Risk of stroke, peripheral emboli
89
What is the prophylaxis for deep vein thombosis/pulmonary embolism?
Surgery
High risk medical patients
Immobilisation
90
What are the 3 factors that contribute to thrombosis known as?
Virchow's triad
91
What are the 3 factors of Virchow's triad?
Stasis
Abnormal blood
Abnormal flow
92
What properties makes the idea anticoagulant?
Oral
No need for monitoring
No interaction with food or drugs
Given once or twice a day with fixed dose irrespective of weight or age
93
What are examples of anticoagulants?
Warfarin
Dabigatran
Rivaroxaban
Apixaban
Edoxaban
94
What is warfarin?
Vitamin K antagonist
95
How does dabigatran work?
Direct thrombin inhibitor
96
How does rivaroxaban, apixaban and edoxaban work?
Direct Xa inhibitors
97
How does warfarin inhibiting vitamin K allow it to be an anticoagulant?
Vitamine K is reduced to 'complete' clotting factors, warfarin prevents this
98
How is warfarin therapy monitored?
Regular international normalised ratio (INR)
Watch if therapy altered
Patient education
Alcohol intake
99
What does INR stand for?
International normalised ratio
100
What is international normalised ratio (INR)?
Actual prothrombin time/standard prothrombin time
101
What is the normal international normalised ratio (INR)?
1
102
What is the range of therapeutical international normalised ratio (INR)?
2.5-4 depending on the clinical indication
103
What are some adverse affects of warfarin?
Bleeding (dose related)
Interactions with multiple other drugs
Teratogenic
104
How is warfarin teratogenic?
Causes retroplacental and foetal intracerebral bleeding
Avoid in first and third trimester
105
What are some drugs that interact with warfarin and promote its activity?
Aspirin
Antibiotics (oral)
106
What are some drugs that interact with warfarin and decrease its activity?
Vitamine K
Barbiturates
107
What is cytochrome P450?
Proteins from the superfamily containing heme as a cofactor, involved in the formation and breakdown of various molecules
108
What are some inhibitors of cytochrome P450?
Omeprazole
Erythromycin
Ethanol
109
What are some inhibitors of cytochrome P450?
Alcohol
Barbiturates
110
What is a safe alternative to warfarin?
Direct oral anticoagulants (DOAC)
111
What does DOAC stand for?
Direct oral anticoagulants
112
How does atrial fibrillation prevalence change with age?
Massively increase, going for \<1% of \<65 years old to 10% in \>75 years old
113
How does risk of stroke with atrial fibrillation change with age?
Increases with age
