Arrhythmias Flashcards
1
Q
What is atrial fibrillation?
A
Chaotic, disorganised atrial activity
Irregular atrial rhythm at 300-600 bpm
2
Q
What mechanism causes atrial fibrillation?
A
Chaotic re-entrant impulse conduction
All meaningful atrial contraction is lost and micro-pathway compare with each other
Ectopic focus around the pulmonary veins
3
Q
What causes AF?
A
HF/IHD Hypertension MI PE Mitral valve disease Pneumonia Hyperparathyroidism
4
Q
What are associated causes of AF?
A
Alcohol abuse Congenital heart disease Cardiac surgery COPD Septicaemia
5
Q
What is paroxysmal AF?
A
<48 hours, often recurrent
6
Q
What is persistent AF?
A
> 48
Can still be cardioverted to NSR
7
Q
What is permanent AF?
A
Can’t restore NSR
8
Q
What are symptoms/signs? (AF)
A
May be asymptomatic Chest pain Palpitations Dyspnoea Faintness Sweatiness Irregularly irregular pulse
9
Q
What are investigations? (AF)
A
ECG - absent P waves, irregular QRS complexes, “f”-waves
10
Q
What are complications of AF?
A
Embolic stroke
11
Q
What are the three aims of AF treatment?
A
Rate control
Restore NSR
Maintain NSR
12
Q
Which drugs can be used for rate control? (AF)
A
Digoxin (if HF)
Beta-blocker
Verapamil or diltiazem
13
Q
What is digoxin?
A
Cardiac glycoside
14
Q
What is the mechanism of digoxin?
A
Binds (blocks) to alpha subunit of sarcolemma Na/K/ATPase in competition with K
Increase Na-Ca exchange
Increase store of Ca in SR
Increase contractility
15
Q
What are indirect effects of Digoxin?
A
Increase vagal activity
Slow AV discharge and AV node conduction
Increase refractory period
16
Q
What are direct effects of digoxin?
A
Shorten AP and refractory period in atrial/ventricular myocytes
17
Q
Toxic concentrations of digoxin cause?
A
Membrane depolarisations and oscillatory after-potentials
18
Q
What are side effects of dioxin?
A
Heart block Propensity to cause arrythmias Nausea Vomiting Diarrhoea Disturbance of colour vision
19
Q
Why can digoxin cause heart block?
A
Excessive AV node depression
20
Q
What are methods to restore NSR? (AF)
A
DCCV
AADs
21
Q
AADs generally inhibit specific ion channels with intention of…?
A
Suppression of abnormal electrical activity
22
Q
What is the mechanism and effect of Disopyramide?
A
Block/unblock sodium channels at moderate rate
Slow rate of rise of AP and prolong refractory period
23
Q
What is the mechanism and effect of Flecainide?
A
Slow block/unblock of Na channels
Strongly depress conduction in myocardium and reduce contractility
24
Q
What is the mechanism and effect of Lignocaine?
A
Block/unblock Na channels at rapid rate
Prevent premature beats
25
Lignocaine primary affects sodium channels in the area of the myocardium that?
Rapidly firs APs due to rapid unbinding (Na channels)
26
What is the main use of Lignocaine?
Post-MI ventricular arrhythmias
27
What is metoprolol?
A beta-adrenoceptor antagonist
28
What is the mechanism and effect of metoprolol?
Decrease rate of depolarisation in SA and AV nodes
| Suppress sympathetic drive that may trigger V-tach
29
What is the mechanism and effect of Amiodarone?
Slow depolarisation of AP by block of K channels
Increase AP duration and effective refractory period
Suppress re-entry
30
Amiodarone is mainly used to treat?
SVT and VT
31
What are side effects of amiodarone?
Pulmonary fibrosis
Thyroid disorders
Photosensitive reactions
Peripheral europathy
32
What is the mechanism and effect of Veramapil?
Blocks L-type Ca channels
Slow conduction and prolong refractory period in AV node and bundle of His
Slow conduction in SA/AV nodes & decrease force of cardiac contraction
33
What is Veramapil used for? (AF)
Prophylaxis (adenosine for acute) of atrial fibrillation and flutter
34
What are methods for NSR maintenance? (AF)
AADs
Catheter ablation of ectopic focus (pulmonary veins)
Surgery (Maze procedure)
35
What is atrial flutter?
Rapid and regular form of atrial tachycardia (250-350 bpm)
36
Atrial flutter is usually _____ with espides lasting?
Paroxysmal
| Seconds-years
37
What is the mechanism behind atrial flutter?
Macro re-entrant pathways
| Circuit confined to the atrium
38
What are signs and symptoms of Atrial flutter?
Palpitations
Dyspnoea
Fast and steady pulse
39
How is Atrial flutter diagnosed?
ECG
40
How is Atrial flutter treated?
```
Termiantion (rapid atrial pacing, cardioversion or AADs)
May convert spontaenously
RF ablation
Warfarin to prevent thromboembolism
Obesity and alcohol reduction
Anticoagulants to reduce stroke risk
```
41
What is sinus bradycardia?
HR <60 bpm
42
What can cause sinus bradycardia?
Physiological (athletes)
Drugs (beta-blockers)
Ischaemia (common in inferior STEMIs)
43
how do you treat sinus bradycardia?
Atropine
44
Atropine is an example of a?
Non-selective muscarinic ACh receptor antagonis
45
Atropine increases?
HR
46
Atropine is the 1st line management of?
Severe symptomatic bradycardia (particularly following MI)
47
In MI atropin is given in?
Incremental doses
48
Atropin is used in ________ poisoning?
Anticholinesterase
49
What is the effect of ACh activating M2 muscarinic cholinoceptors?
Decrease activity of adenylate cycles + opens potassium channels to cause hyper polarisation of SA node
Decreases HR, contractility and conduction in AV node
50
How is sinus bradycardia treated if the patient is harm-dynamically compromised?
Pacing
51
What causes supraventricular tachycardia?
Re-entry involving the AV & SA node or atrial tissue
52
What is SVT?
Narrow complex tachycardia
53
Which ECG features distinguish SVT?
Rate > 100 bpm
| QRS width <120 ms
54
What is the atrial firing rate in SVT?
140-250
55
How do you manage acute SVT?
Increase vagal tone via valsalva maneouvre +/- carotid massage
56
Which drugs slow conduction in the AV node?
(iv) adenosine and veramapil
57
Adenosine activates ______
A1-adenosine receptors
58
What is the effect of A1-adenosine receptor activation?
opens ACh sensitive K-channels
hyperpolarise AV node briefly
Suppress impulse conduction
59
Adenosine is used to stop _____ SVT
paroxysmal
60
Describe Torsade de Points
Heart rate of 200-259 bpm
Irregular rhythm
Long QT, wide QRS, continuously changing QRS
61
How do you treat Torsade de Points?
Magnesium sulphate
62
What is ventricular fibrillation?
Chaotic ventricular activity
No QRS complexes
Random frequency and amplitude
Uncoordinated electrical activity
63
Patients in V-fib may be ________ unstable
haemodynamically
64
How do you treat V-Fib?
CPR
| Defibrillation
65
What is monomorphic ventricular tachycardia?
Broad complex rhythm
Rapid rate
Constant QRS morphology
66
What is polymorphic V-tach?
Torsade de Points
67
V-tach patients may be _______ unstable
haemodynamically
68
How do you treat V-tach?
precordial thump if defib not immediately available
| DCCV
69
If a patient is V-tach is stable you can consider?
AADs
| Inmeantime prepare for DCCV
70
How can you confirm diagnosis of V-tach if unsure?
Adenosine
71
How is V-tach treated long-term?
Correct ischaemia (revascularisation if possible)
Optimise CHF treatment therapy
ICD if life-threatening
VT catheter ablation
72
What can an ICD do?
Terminate VT/VF, anti-tachycardia pacing, cardioversion and defibrillation + pace atria and ventricles for bradycardia
73
What is Wolff-Parkinson White Syndrome?
Congenital accessory conductance pathway between atria and ventricles
74
What symptoms/signs are there in WPWS?
SVT (may be due to AVRT - AV nodal re-entrant pathway)
| Pre-excited AF or pre-excited atrial flutter
75
How do you diagnose WPWS?
```
ECG - short PR interval, wide QRS
Delta wave (slurred upstroke)
```
76
How do you treat WPWS?
Electrophysiology and radio frequency ablation of accessory pathways
77
What is radio frequency ablation (RFCA)?
Selective cautery of cardiac tissue to prevent tachycardia targeting either automatic focus or part of a re-entry circuit
78
What are causes of heart block?
```
Ageing
Acute MI
Myocarditis
Amyloid
Beta-blockers of CCBs
Post-aortic valve surgery
Calcific aortic valve disease
Lenegre's disease (genetic)
Myotonic dystrophy
```
79
What is Lenegre's disease?
Idiopathic fibrosis of the cardiac conduction system
80
What is 1st degree Heart block?
Prolonged Pr interval - delayed conduction
81
What are complications of first degree heart block?
More advanced block may over time
82
How do you manage first degree heart block?
Ya don't
83
What are the two types of second degree heart block?
Mobitz Type I and II
84
What is 2nd degree heart block mobitz type 1?
Cyclical prolongation of PR interval with eventual dropped beats
85
What are causes of Mobitz type I?
Usually increased vagal tone
| Others: myocardial ischaemia, side effect of CCB, digitals or beta-blockers
86
What is 2nd degree Heart block Mobitz type II?
P wave not always followed by QRS )2:1 or 3:1)
87
What are complications of mobitz type II?
May progress to complete heart block
88
How do you manage mobitz type II?
Permanent pacemaker indicated
89
What is third degree heart block?
Complete heart block
Atrial and ventricular dissociation
Lonely P waves
Chaotic PR intervals
90
How do you manage complete heart block?
Ventricular pacing
91
What ECG changes are observed in a right bundle branch block?
V1 for M wave and V6 for W wave
92
Why is the cardiac axis unchanged is isolated RBBB?
Because left ventricular activation proceeds normally via the left bundle branch
93
What is seen on ECG for LBBB?
V6 for M wave and V1 for W wave
94
What is sinus tachycardia?
HR > 100 bpm
95
What are causes of sinus tachycardia
Physiological (anxiety, fever, hypotension, anaemia)
Drugs
Other
96
How do you treat sinus tachycardia?
Underlying cause
| Beta-adrenergic bockers
97
What cause Ventricular ectopic beats?
Structural (LH/HF/myocarditis), metabolic (IHD; electrolytes) or inherited conditions
98
You should investigate further if ventricular ectopic beats are worse on?
Exercise
99
How do you treat ventricular ectopic beats?
Beta blocker +/- ablation of focus
100
How do beta blockers help to restore sinus rhythm?
Decrease excessive sympathetic drive - delay conduction through the AV node (to ventricles) and help restore sinus rhythm
101
What are the side effects of beta-blockers?
```
Bronchospasm
Aggravation of cardiac failure
Bradycardia
Hypoglycaemia (if poorly controlled diabetes)
Fatigue
Cold extremities
```
102
Atrial ectopics can be asymptomatic or cause?
Palpitations
103
Atrial ectopic are usually not treated but _____ may help. Key to management is?
```
beta-blockers
Avoiding stimualnts (caffeine / cigarettes)
```
104
What are the causes of arrhythmias?
Afterdepolarisation - triggered activity
Structural
Functional
105
What is given to diagnose AF if it is so fast that it appears regular but there are subtle interval changes?
Give adenosine to slow AV conduction and visualise fibrillatory waves in background
106
When should you NOT give a patient adenosine?
If they have had a previous heart attack or very brittle/uncontrolled asthma
107
Ventricular fibrillation is always associated with?
Loss of consciousness
108
What is defined as a prolonged PR interval?
>200 ms (> 5 small squares)
109
Tall tented T-waves indicate?
Hyperkalaemia
