Arrythmias Flashcards
(154 cards)
1
Q
Presentation of arrhythmias
A
Asymptomatic Palpitations SOB Chest pain Fatigue Embolism
2
Q
Investigations of arrhythmias
A
ECG
Blood tests esp TFTs
ECHO
3
Q
Therapeutic options for arrythmias
A
Digoxin / BB / Ca-antagonist + warfarin (aspirin if low risk)
vs
class Ic/III drugs +/- DC cardioversion
Electrical approaches (occasionally)
- pace and ablation of AV node
- substrate modification e.g. pulmonary vein ostial ablation, maze procedures
Anticoagulation
4
Q
Definition of an arrhythmia
A
Any deviation from the normal rhythm of the heart
5
Q
Types of arrhythmias
A
Supraventricular arrhythmia
Ventricular arrhythmia
Heart block
6
Q
What are the supraventricular arrhythmias?
A
AF
SVT (junctional)
7
Q
What does AF stand for?
A
Atrial fibrillation
8
Q
What does SVT stand for?
A
Supra ventricular tachycardia
9
Q
What are the ventricular arrhythmias?
A
Ventricular tachycardia
Ventricular fibrillation
10
Q
What do you look at in an ECG?
A
Rhythm Rate QRS duration P wave visible before each QRS complex P-R interval (< 5 small squares)
11
Q
Anything above 5 small squares in a P-R interval would be classified as what?
A
1st degree block
12
Q
What is a 1st degree AV block caused by?
A
Conduction delay through the AV node but all electrical signals reach the ventricles
13
Q
Does 1st degree AV block tend to cause problems?
A
No
14
Q
Normal P-R interval
A
0.12 - 0.2 s
3 - 5 small squares
15
Q
What would be seen on the ECG in 1st degree heart block?
A
Prolonged P-R interval (>5 small squares)
16
Q
Types of 2nd degree heart block
A
Mobitz type 1 or Wenckeback 2nd degree AV block
Morbitz Type II 2nd degree heart block
17
Q
What is seen on an ECG in Mobitz Type 1 degree AV block?
A
Progressive PR prolongation until the sixth P wave fails to conduct through the ventricle - dropped QRS complex (P wave ratio 1:1 for 2, 3 or 4 cycles then 1:0)
P-P interval remains constant
Rate normal or slow
P wave rate normal but faster than QRS rate
18
Q
What is seen on an ECG in Mobitz Type II 2nd degree heart block?
A
For example 2nd and 8th P waves are not conducted through the ventricle
P-P interval remains constant
Rate normal or slow
P wave ratio 2:1, 3:1
P wave rate normal but faster than QRS
P-R interval normal or prolonged but constant
19
Q
What is 3rd degree heart block?
A
Complete heart block
20
Q
What is seen on an ECG in 3rd degree heart block?
A
P wave rate regular P wave bears no relation to QRS complexes or ventricular activity (unrelated P wave) Slow rate QRS prolonged Varied P-R interval Complete AV block
21
Q
When does 3rd degree heart block occur?
A
When atrial contractions are ‘normal’ but no electrical conduction is conveyed to the ventricles. The ventricles generate their own signal through an ‘escape mechanism’ from a focus somewhere in the ventricle.
The ventricular escape beats are usually slow
22
Q
What would be seen on an ECG in Atrial flutter?
A
Regular rhythm Rate approx. 110bpm QRS usually normal P wave replaced with multiple F (flutter) waves, usually at a ratio of 2:1 (2F - 1QRS) but sometimes 3:1 P wave rate 300bpm P-R interval not measurable
23
Q
Is the AV node involved in Atrial flutter?
A
No
24
Q
What does AF stand for?
A
Atrial fibrillation
25
What happens in atrial flutter?
Abnormal tissue generating rapid heart rate is in the atria but AV node not involved
26
What happens in AF?
Many sites within the atria generating their own impulses, leading to irregular conduction of impulses of the ventricles to generate the heartbeat.
Irregular rhythm can be felt on palpation of the pulse
27
Presentation of AF
```
Asymptomatic
Palpitations
Fatigue
Fainting / presyncope
Chest pain
Poor exercise tolerance
CHF
```
28
What does AF look like on an ECG?
```
Rhythm irregularly irregular
Rate 100 - 160 bpm but slower if on meds
QRS normal
P wave not distinguishable
P-R interval not measurable
```
29
What is SVT?
Supraventricular tachycardia
1. AV nodal re-entrant tachycardia
2. AV re-entrant tachycardia
30
Presentation of SVT
Palpitations
Dizziness
Dyspnoea
31
Treatment of SVT
1st line
- vagal maneuvers e.g. Valsalva manourvre or carotid sinus massage
If fail - adenosine
Electrical cardioversion
32
What happens in SVT?
A narrow complex tachycardia or atrial tachycardia which originates in the atria but is not under direct control from the SA node
33
What age groups can SVT occur in?
All age groups
34
What is seen on an ECG in SVT?
```
Regular rhythm
Rate 140 - 220 bpm
QRS duration usually normal
P wave often buried in preceding T wave
P-R interval depends on site of supraventricular pacemaker
```
35
Where are the signals in SVT coming from?
NOT BY SINUS NODE
| Coming from a collection of tissue around and involving the AV node
36
What does WPW Syndrome stand for?
Wolff-Parkinson White Syndrome
37
What is WPW Syndrome?
A condition that causes the heart to beat abnormally fast for periods of time, due to an extra electrical connection in the heart. This allows signals travel round in a loop causing episodes where the heart beats really fast
Have episodes of SVT
38
When does WPW syndrome develop?
Congenital but symptoms may not arise until later in life
39
Presentation of WPW syndrome
```
Palpitations
Syncope
SOB
Chest pain
Sweating
Anxious
Finding physical activity exhausting
Fainting
```
40
Treatment of WPW syndrome
No treatment usually required
41
Treatment of ventricular fibrillation
Cardiac arrest protocol - immediate defibrillation
42
What happens in ventricular fibrillation
Disorganised electrical signals cause the ventricles to quiver instead of contract in a rhythmic fashion.
43
When may Ventricular fibrillation occur?
During or After MI
44
ECG in ventricular fibrillation
Rhythm irregular
Rate 300+, disorganised
QRS duration not recognisable
P wave not seen
45
Presentation of ventricular tachycardia
Palpitations
Chest pain
Dyspnoea
Dizziness/syncope
46
What usually causes ventricular tachycardia?
Structural heart disease
47
Treatment of ventricular tachycardia
Cardiac arrest protocol
DC cardioversion
Drugs
48
Prevention of ventricular tachycardia
Prevent underlying cause
AA drugs
ICU
49
ECG of ventricular tachycardia
Regular rhythm
Rate 180-190 bpm
QRS duration prolonged
P wave not seen
50
What happens in ventricular tachycardia?
Abnormal tissues in the ventricles generating a rapid and irregular heart rhythm
Poor CO is usually associated with this rhythm causing the pt to go into cardiac arrest
51
What would you see in Torsades de Pointes due to CHB/AF
Short long short RR intervals and prolonged repolarisation
| Long QT syndrome
52
Indications for ICD therapy
Secondary prevention
- cardiac arrest due to VF/VT not due to transient or reversible causes e.g. early phase of acute MI
- Sustained VT causing syncope or significant compromise
- Sustained VT with poor LV function
53
Definition of sinus bradycardia
A heart rate less than 60bpm
54
Examples of causes of bradycardia
Cardiac causes
Increased vagal tone from drug abuse
Hypoglycaemia
Brain injury with increased ICP
55
ECG of sinus bradycardia
```
Regular rhythm
Rare < 60 bpm
QRS duration normal
P wave visible before each QRS complex
P-R interval normal
```
56
What is sinus bradycardia often caused by?
Patients on beta blockers
57
What is sinus tachycardia?
An excessive heart rate > 100bpm which originates from the SA node
58
Example causes of sinus tachycardia
Fright
Illness
Exercise
Shock
59
ECG of sinus tachycardia
```
Regular rhythm
Rate > 100bpm
QRS normal duration
P wave visible before each QRS
P-R interval normal
```
60
When does sinus arrest occur?
Occurs when there is a sudden absence of electrical activity initiated by the SA node
Results in a pause in electrical activity seen on tracing. Hence there would be a drop in BP
The longer the pause, the further the BP will drop
61
What length of pause in sinus arrest is deemed a medical emergency?
6 Seconds
62
ECG after the pause in sinus arrest
Constant R - R intervals
| Rhythm tracing irregular
63
What is sick sinus syndrome post MI?
Asymptomatic SA node depression post MI
64
What are ectopic beats?
Beats that occur before the next beat arising from the sinus node
65
Where can ectopic beats arise from?
Either atria or ventricles of heart
66
What do ectopic beats look like on ECG if they arise from the atria?
Very similar to normal beats
67
What do ectopic beats look like on ECG if they arise from ventricles?
Look different to normal beats - wider and different shape as travel through His Purkinje system which takes longer
68
Goals for medications for patients with AF
Maintain sinus rhythm
Avoid risks of complications e.g. stroke
Minimise symptoms
69
What should patients with AF be given and why?
Warfarin if high risk
Clopidogrel
BOTH to minimise risk of thromboembolic events
Anti arrhythmic drugs
70
Unstable patients requiring immediate DC cardioversion in AF
Decompensated HF
Hypotension
Uncontrolled angina/ischaemia
71
Indications for a temporary pacemaker
Intermittent or sustained symptomatic bradycardia, particularly syncope
Prophylactic when patient at high risk for development for severe bradycardia e.g. 2nd or 3rd degree AV block, post anterior MI, even when asymptomatic
72
Indications for permanent pacemaker
Symptomatic or profound 2/3rd degree AV block, particularly when the cause is unlikely to disappear
Probably Mobitz type II 2nd / 3rd degree AV block even if asymptomatic
AV block associated with Neuromuscular diseases
After or in preparation for AV node ablation
Alternating RBBB/LBBB
Syncope when bifasicular/trifasciular block and no other explanation
Sinus node disease associated with symptoms
Carotid sinus hypersensitivity/malignant vasovagal syncope
73
What pump in the cells controls the resting membrane potential?
Sodium-potassium ATPase Pump
74
What is an AP?
A Change in the distribution of ions causes cardiac cells to become excited - the movement of ions across the cardiac cells membrane results in the propagation of an electrical impulse which leads to the contraction of the myocardial muscle
75
What is the classification of drugs used to treat arrhythmias?
Vaughan-Williams classification
76
What are the Vaughan Williams classifications of drugs?
```
Class I (a, b, c)
Class II
Class III
Class IV
Other
```
77
What are the Class I drugs?
Membrane stabilising agents
| Fast sodium channel blockers
78
Examples of Class Ia drugs and what they do
Quinide, procainamide, Disopyramide
Block Na channels
Increase the AP duration
79
What are class Ia drugs used for?
```
AF
Premature atrial contractions
Premature ventricular contractions
VT
WFWS
```
80
Class Ib drugs and what they do
Tocainide, phenytoin, lidocaine
Block Sodium channels
Accelerate repolarisation
Decrease AP duration
81
What are class IIb drugs used for?
Ventricular dysrhythmias only (premature ventricular contractions, VT, VF)
82
What are the class Ic drugs and what are they used for?
Encainide, flecainide, propafenone
Block sodium channels (more pronounced effect)
Little effect on AP during or repolarisation
83
What are class Ic drugs used for?
Severe ventricular dysrhythmias
| May be used in AF/flutter
84
What are the class II drugs? Give examples
Beta blockers
- Atenolol
- bisoprolol
- propranolol
85
What do beta blockers do?
Block sympathetic system stimulation, thus reducing transmission of impulses in the hearts conduction system
Depress phase 4 depolarisation
86
What is bisoprolol first line for?
AF
87
What are the class III drugs?
Amoidarone
Bretylium
Sotalol
88
What do the class III drugs do?
Increase AP duration
| Prolong repolarisation in phase 3
89
What are class III drugs used for?
Dysrhythmias that are difficult to treat
Life threatening VT or fibrillation
AF resistant to other drugs
Sustained VT
90
What are the Class IV drugs?
Verapamil
Diltiazem
CCBs
91
What are the class IV drugs used for?
Paroxysmal SVT
| Rate control for AF and flutter
92
Examples of other anti dysrhytmics
Digoxin
| Adenosine
93
What is digoxin? How does it work?
Cardiac glycoside
Inhibits sodium potassium ATPase pump
Positive inotrope - improves strength of cardiac contraction
Allows more calcium available for contraction
94
What is digoxin used for?
HF
AF
Rate control in elderly
95
What needs to be monitored when using digoxin?
Potassium
Drug levels
Toxicity
96
Signs of digoxin toxicity
Vision changes; yellow glow around objects
ECG; changes in T waves. Reverse tick appearance of ST segment in lateral leeds
N + V
Brady or tachycardia
Arrhythmias; VT or VF
97
Treatment of digoxin toxicity
```
Stop digoxin (long half life)
Digibind
```
98
How does digibind work?
Digoxin immune antibody
Binds with digoxin, forming complex molecules
Excreted in urine
99
What is adenosine used for?
Converts paroxysmal SVT to sinus rhythm
100
What does adenosine do?
Slows conduction through the AV node
101
S/E of adenosine
Causes asystole for a few seconds
102
Side effects of all anti-dysrhythmics
ALL cause arrythmias
103
What is amiodarone used for?
VT
| Occasionally SVT
104
Interactions of amoidarone
Digoxin
105
S/Es of amoidarone
```
Striking
- Thyroid (hypo or hyper)
- pulmonary fibrosis
- slate; grey pigmentation
- corneal deposits
- LFT abnormalities
Amoidarone toxicity
```
106
Indications for anticoagulation
AF
DVT/PE
After surgery
Immobilisation
107
Examples of anticoagulants
Warfarin
Dabigatran
Rivaroxaban
Apixaban
108
Pathology of arterial thrombosis and what is it associated with?
```
Adherence of platelets to arterial walls
White in colour (full of cells/platelets)
Assosiated with
- MI
-Stroke
- Ischaemia
```
109
Pathology of venous thrombosis and what is it associated with?
```
Develops in areas of stagnated blood flow (e.g. DVT, LA)
Red in colour
Assosiated with
- CHF
- cancer
- Surgery
```
110
What is warfarin structurally related to?
Vitamin K
111
What does warfarin do?
Inhibits production of active clotting factors
112
Direct effect of warfarin depends on....
Concentration of warfarin in the liver
Rate of accumulation of warfarin (clearance is slow 36 hours)
Long t1/2 of clotting factors - slow onset of actions
113
How is warfarin therapy monitored?
INR
114
What does INR stand for?
International normalised ratio
115
What is INR?
Actual thromboplastin time / Standard thromboplastin time
116
What is a normal INR value?
1
117
What is a therapeutic INR valve?
2.5 - 4.0 depending on clinical indication
118
S/Es of warfarin
Bleeding
| Teratogenic (chondrodysplasia)
119
What trimesters should warfarin be avoided in and why?
1st and 3rd
| Chondrodysplasia
120
How is warfarin metabolised and therefore what drugs does it interact with?
Cytochrome P450 pathway
| Macrolide antibiotics, antifungals, anti epileptic drugs
121
What assess the bleeding risk with warfarin?
CHADS2 score
122
What is looked at in the CHADS2 score?
```
Congestive heart failure
HTN
Age > 75 y/o
DM
Stroke / TIA
(Score 1 for each or 2 for stroke)
```
123
Features of torsades de pointes
Long QT syndrome
| Polymorphic VT
124
Causes of long QT syndrome
```
Genetic
Electrolyte abnormalities
- Hypocalcaemia
- Hypomagnesaemia
- Hypokalaemia
Drugs
- anti arrythmics
- antibiotics (erythromycin, clarithromycin, ciprofloxacin)
- Psychotropic drugs (SSRIs, TCAs, Neuroleptic agents)
CNS lesions
- SAH
- Ischaemic stroke
Malnutrition
Hypothermia
```
125
Who is adenosine contraindicated in and therefore what is used instead as treatment for SVT?
Asthmatics - use verapamil instead
126
Prevention of episodes of SVT
Beta blockers
| Radio-frequency ablation
127
ECG features of hypokalaemia
```
U waves
Small or absent T waves
Prolonged PR interval
ST depression
Long QT
```
128
Appearance of atrial flutter on ECG
Sawtooth appearance
129
What makes up bifasicular block?
Combination of RBBB + left anterior hemiblock or posterior hemiblock e.g. RBBB with left axis deviation
130
What makes up trifasciular block?
Features of bifasciular block as above + 1st degree heart block
131
Treatment of an asthmatic with AF
Anticoagulation
| Rate limiting CCB (instead of BB) - dilitiazem
132
Rate control vs rhythm control as treatment in AF
```
Rate control as 1st line to people with AF
Rhythm control as 1st line if
- AF with reversible cause
- Coexistent heart failure
- First onset AF
```
133
When is immediate DC cardioversion used in AF?
When there is life threatening haemodynamic instability caused by new onset AF
134
What does hypothermia show on the ECG?
J waves / Osborn wave
| Prolongation of all ECG intervals
135
Causes of LBBB
MI
| Aortic stenosis
136
ECG finding of digoxin toxicity
Reverse tick sign
137
What is T wave inversion on an ECG a sign of?
Ischaemia
138
What is a holter monitor and what is it frequently used in?
Records a continuous ECG for 24, 48 or 72 hours
| Used for investigation of AF
139
Normal corrected QT interval
< 430 ms in males
| < 450 ms in females
140
What is long QT syndrome?
Rare inherited or acquired disorder where delayed repolarisation of the ventricles increases the propensity to ventricular tachyarrythmias - may lead to syncope, cardiac arrest or sudden death
141
Treatment of symptomatic bradycardia
IV atropine
142
Treatment of WPW syndrome
Accessory pathway ablation
143
What agents are used to control rate in patients with AF?
BBs
CCBs
Digoxin
144
What agents are used to maintain sinus rhythm in patients with a history of AF?
Sotalol
Amoidarone
Flecainide
145
Factors favouring rate control in AF
> 65 y/o
| History of IHD
146
Factors favouring rhythm control in AF
```
< 65 y/o
Symptomatic
1st presentation
Lone AF or AF secondary to corrected precipitant (e.g. alcohol)
CHF
```
147
Treatment of tosardes de pointes
IV magnesium
148
Common ECG variants of athletes
High vagal tone
- sinus bradycardia
- 1st degree AV block
- Wenckebach phenomenon (2nd degree AV block Mobitz type I)
- Junctional escape rhythm
149
What are the two most important causes of VT?
1. Hypokalaemia
| 2. Hypomagnesia
150
What is Mobitz type II an indication for?
Pacemaker
151
What is used to treat symptomatic bradycardia if atropine fails?
External pacing
152
What is used to pharmacologically cardiovert AF?
Amiodarone + Flecainide
153
When would pharmacological vs electrical cardioversion be used in AF?
Haemodynamically unstable - electrical (and if stable but symptoms > 48 hours)
Haemodynamically stable - pharmacological
154
Anticoagulation rules with cardioversion of AF
Patients must be either anticoagulated or have had symptoms < 48 hours to reduce the risk of stroke
Cardioversion must be delayed for at least 3 WEEKS of anticoagulation - during this rate control (BB) should be used
