Arrythmias

Question 1

Presentation of arrhythmias

Answer 1

Asymptomatic
Palpitations
Dyspnoea
Chest pain
Fatigue
Embolism

Question 2

Investigations for arrhythmias

Answer 2

12 lead ECG (24 hours)
Blood test (esp. thyroid function)
ECHO

Question 3

Therapeutic options for arrhythmias

Answer 3

Rate control vs. Rhythm control

1. Digoxin/Beta-blocker/Ca-antagonist PLUS warfarin (or aspirin if low risk)
2. Electrical Approaches occasionally
   - Pace and ablation of AV node
   - Substrate modification e.g. pulmonary vein ostial ablation, maze procedures

Question 4

Types of arrthymias

Answer 4

1. Sinus arrhythmias
2. Supraventricular Arrhythmias
   - Atrial fibrillation
   - Supraventricular tachycardia
3. Ventricular arrhythmia
   - Ventricular tachycardia
   - Ventricular fibrillation
4. Heart block

Question 5

A normal sinus rhythm ECG

Answer 5

Rhythm: regular
Rate: 60-99bpm
QRS duration: normal
P wave: visible before each QRS complex
P-R interval: normal (<5 small squares)

Question 6

1st degree heart block on ECG

Answer 6

Prolonged P-R interval

Question 7

2nd degree heart block on ECG

Answer 7

Mobitz Type 1:
- Progressive PR prolongation until a P wave (e.g. 6th) fails to conduct through the ventricle
Mobitz Type 2:
- P wave ratio 2:1, 3:1
- QRS duration prolonged

Question 8

3rd degree heart block on ECG

Answer 8

Complete heart block

• Rate = slow
• P wave = constant but bear no relation to QRS complex or ventricular activity
• P-R interval = variation

Question 9

Atrial Flutter Treatment

Answer 9

Control ventricular rate and thromboembolic risk
Usually cardiovert
Prevent with AA drugs or RFA of cavotricuspidsthmus

Question 10

Atrial Flutter on an ECG

Answer 10

P waves replaced with multiple F (flutter waves) usually at a ratio at 2:1 (2F:1QRS) but sometimes 3:1
High heart rate
P-R interval not measurable

Question 11

Atrial Fibrillation on an ECG

Answer 11

Rhythm: irregularly irregular
Rate usually high but slower if on medication
P wave not distinguishable
P-R interval not measurable

Question 12

Supraventricular tachycardia types

Answer 12

AV-nodal re-entrant tachycardia

AV re-entrant tachycardia (due to accessory pathway - WPW if overt)

Question 13

Supraventricular tachycardia on an ECG

Answer 13

High heart rate
P Wave often buried in preceding T wave
P-R interval depends on site of supraventricular pacemaker

Question 14

Symptoms of Wolff-Parkinson White syndrome

Answer 14

Palpitations
Syncope
SOB
Chest pain
Sweating
Anxious
Finding physical activity exhausting
Fainting

Question 15

Ventricular fibrillation on an ECG

Answer 15

Rate over 300bpm, disorganised
Rhythm is irregular
P wave not seen
DEFIBRILLATE

Question 16

Ventricular tachycardia on an ECG

Answer 16

Rate high
QRS duration prolonged
P wave not seen

Question 17

Indications for ICD therapy

Answer 17

Secondary prevention

• Cardiac arrest due to VF/VT not due to transient or reversible cause e.g. early phase of acute MI
• Sustained VT causing syncope or significant compromise
• Sustained VT with poor LV function

Question 18

Causes of sinus bradycardia

Answer 18

Healthy athletic person = may be normal
Drug abuse
Hypoglycaemia
Brain injury with increased intracranial pressure

Question 19

Causes of sinus tachycardia

Answer 19

Stress
Fright
Illness
Exercise

Question 20

Symptoms of AF

Answer 20

Palpitations
Fatigue
Poor exercise tolerance
Presyncope or syncope
Generalised weakness, dizziness, fatigue

Question 21

Goals of treatment for AF

Answer 21

Maintain sinus rhythm
Avoid risks of complications e.g. stroke
Minimise symptoms

Question 22

Treatment for AF

Answer 22

Warfarin for patients at high risk of complications e.g. stroke
Clopidogrel
Antiarrhythmic drugs

Question 23

Unstable patients requiring immediate DC cardioversion in AF include…

Answer 23

Patients with decompensated congestive heart failure
Patients with hypotension
Patients with uncontrolled angina/ischaemia

Question 24

Indications for a pacemaker

Answer 24

Temporary
- Intermittent or sustained symptomatic bradycardia, particularly syncope
- Prophylactic when patient high risk for development of severe bradycardia (e.g. 2nd/3rd degree heart block, post anterior MI, even when asymptomatic)
Permeant
- Symptomatic or profound 2nd/3rd degree heart block particularly when cause unlikely to disappear
- Probably Mobitz type II 2nd degree/3rd degree AV block even if asymptomatic
- AV block associated with neuromuscular diseases
- After (or in preparation for) an AV node ablation
- Alternating RBBB/LBBB
- Syncope when bifascular/trifascular block and no other explanation
- Sinus node disease associated with symptoms
- Carotid sinus hypertension/malignant vasovagal syncope

Question 25

Vaughan-Williams Classification of drugs used to treat arrthymias

Answer 25

``` Class I (1a, 1b, 1c) Class II Class III Class IV Other ```

Question 26

Class I antiarrhytmic drugs

Answer 26

Membrane stabilising agents | Fast Na Channel blockers

Question 27

Class Ia drugs

Answer 27

Quinide Increase action potential duration Used for AF, Premature atrial contractions, premature ventricular contractions, ventricular tachycardia, WPW syndrome

Question 28

Class Ib drugs

Answer 28

Lidocaine Accelerate repolarisation and decrease action potential duration Used for ventricular dysrhythmias only

Question 29

Class Ic drugs

Answer 29

Propafenone Block Na channels with a more pronounced effect Little effects on AP or repolarisation Use for severe ventricular dysrhythmias and possible AF/flutter

Question 30

Class II

Answer 30

``` Beta blockers Atenolol e.g. Reduce/block sympathetic nervous system Supraventricular and ventricular dysrhythmias First line for AF (Bisoprolol) ```

Question 31

Class III

Answer 31

Increase action potential duration Block K channels Amoidarone Used for difficult to treat arrhythmias

Question 32

Class IV

Answer 32

Verapamil Calcium channel blockers Used for paroxysmal SVT, rate control for AF and flutter

Question 33

Digoxin

Answer 33

Cardiac glycoside Inhibits Na/K ATPase pump Improves strength of cardiac contraction (positive inotrope)

Question 34

Adenosine

Answer 34

Slows conduction through AV node Used to convert paroxysmal SVT to sinus rhythm Only administered as fast IV push

Question 35

Digoxin toxicity signs

Answer 35

Vision changes: yellow glow around objects ECG: changes in T waves, reverse tick of ST segment in lateral leads Nausea and vomiting Brady/tachycardia Arrythmias: VT or VF

Question 36

Treatment for digoxin toxicity

Answer 36

Stop digoxin - but long half life | Digibind (digoxin immune antibody)

Question 37

Amoidarone side effects (striking side effects)

Answer 37

``` Thyroid problems Pulmonary fibrosis Slate: grey pigmentation Coreal deposits LFT abnormalities ```

Question 38

Indications for anticoagulation

Answer 38

AF - reduce risk of stroke by 80% DVT/PE After surgery Immobilisation (prophylactic)

Question 39

Anticoagulant drugs

Answer 39

``` Warfarin Dabigatran Rivaroxaban Apixaban (Edolaban) ```

Question 40

Monitoring warfarin therapy

Answer 40

INR (international normalised ratio) Actual thromboplastin time/standard thromboplastin time Normal INR is 1 Therapeutic INR normally 2.5-4

Question 41

Adverse effects of warfarin

Answer 41

Bleeding | Teratogenic (chondrosdyplasia)

Question 42

Drug interactions of warfarin

Answer 42

Macrolide antibiotics Antifungals Anti-epileptics

Question 43

Bleeding risk on warfarin - CHADS2

Answer 43

``` Congestive Heart failure - 1 Hypertension - 1 Age - >75 years - 1 Diabetes mellitus - 1 Stroke/TIA - 2 ```