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Flashcards in Cardiac Deck (54)
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1

Describe the stages of de and repolarisation in the contraction of the heart

0: rapid depolarisation due to influx of Na+
1: Rapid early repolarisation, efflux K+ with inactivation of fast Na+ channels
2: Repolarisation slowed by Ca2+ influx
3. Rapid repolarisation, K+ efflux
4. Diastole with steady state resting transmembrane voltage

2

What is AF?

Most common arrhythmia (1-2% population)
Atrial fibrillation
Irregular baseline, ventricle contraction irregularly irregular
Increases risk of hospitalisation, stroke, cardiomyopathy

3

Treatment of AF

Cardioversion:
Electrical w/DC current
Chemical: amiodarone/flecanide

4

When should flecanide be avoided in AF?

Don’t use flecanide with underlying ischaemic heart disease or structural abnormalities

5

Do you anticoagulate AF patients?

Yes
Use CHA2DS2 VASc score and HAS-BLED can quantify stroke risk
WARFARIN, NOAC (DABIGATRAN, RIVAROXABAN)

6

If cardioversion for AF does not work, what do you do?

Rate control: Beta-blockers, VERAPAMIL, DIGITALIS
Rhythm control: SOTALOL, FLECANIDE, AMIODARONE
Catheter ablation (if ectopic foci and paroxysmal AF)

7

8 causes of pathological bradycardia

• Cardiac surgery
• Chronic degeneration of AV or SA nodes
• Cholestatic jaundice
• Hypothermia
• Hypothyroidism
• Ischaemia/infarction of SA node
• Raised ICP
• Drugs: amiodarone, beta-blockers, diltiazem/verapamil, lithium salts, morphine, clonidine, anticholinesterase inhibitors (donepezil, rivastigmine)

8

Treatment of pathologic/symptomatic bradycardia

Stop ß-blockers/other causative drugs
Treat underlying cause (levothyroxine)
Acutely Atropine (reduces vagal inhibition) IV 500micrograms, repeat every 3-5mins

9

What is a sinus pause?
Causes?
Symptoms?

Sa node fails to generate impulse
Caused by:
• Acute myocarditis
• Digoxin toxicity
• Fibrosis of SA node (ageing)
• SE of antiarrythmic drug
• MI
• Stroke
Breathlessness, lethargy, dizziness, collapse, falls

10

Treatment of sinus pause?

Permanent pacemaker

11

What is sick sinus syndrome?

Palpitations caused by sinus bradycardia, sinus pause, paroxysmal atrial/tachy arrhythmias
Treatment: pacemaker/ rate controlling drugs

12

8 causes of AV block

• Cardiomyopathy
• Conduction system fibrosis
• Connective tissue disease
• Hypothyroidism
• IHD
• Radiotherapy
• Sarcoidosis
• Drug induced (beta-blockers, diltiazem, digoxin)

13

When are pacemakers indicated?

Pacemakers are indicated in:
• RBBB/LBBB with intermittent 3rd degree AV block
• Carotid sinus hypersensitivity
• Pauses of >3secs during the day
• Sustained VT with pauses
• Symptomatic bradycardia
• Symptomatic sinus node dysfunction/2nd degree heart block

14

How do you differentiate between tachyarrhythmias?

Is it regular? No
⇒ irregularly irregular AF
⇒ unconscious patient VF

Is the QRS broad?
⇒ Yes means ventricular origin
⇒ No means supraventricular origin

15

What does atrial flutter look like?

P-wave rate>250/min
2:1 or 3:1 P:R ratio
Characteristic saw tooth baseline

16

Treatment of supraventricular tachycardia

Give adenosine to block AV node. If this terminates the tachycardia-> AVRT/AVNRT
If it is independent of AV node-> focal atrial tachycardia
AVRT: atrioventricular re-entry tachycardia
AVNRT: atrial node re-entrant tachycardia

17

How do you treat a patient with a tachyarrhythmia who is haemodynamically compromised?

Electrical cardioversion under anaesthesia and sedation
Then IV amiodarone/beta-blocker

18

How do you manage a haemodynamically stable pt with a tachyarrhythmia?

Continuous ECG monitoring
Vagontonic manoeuvres (carotid massage, valsalva)
IV adenosine
Rate control with IV lidocaine

19

Treatment of supraventricular tachycardia

Rate control (ß-blocker, verapamil, digoxin)
Rhythm control (amiodarone, flecanide, sotalol, DC shock)

20

Prevention of supraventricular tachycardia

Amiodarone
Sotalol
Quinidine
Procainamide

21

Causes of AF

• Atrial septal defect
• Cardiomyopathies
• Diabetes mellitus
• COPD
• CKD
• HTN
• Obesity
• CCF
• Thyroid dysfunction
• Valvular heart disease

22

Define 1st degree heart block

Conduction across AV node is delayed
Prolonged PR interval
Doesn't need treatment

23

Define 2nd degree heart block

Mobitz 1: PR interval progressively lenthens until QRS in dropped
Mobitz 2: Fixed number of p waves conduct (eg 3P to every 1 QRS). Conduction block at bundle of His

24

Where is the conduction block with Mobitz 2 2nd degree AV block?

Bundle of His

25

Define 3rd degree heart block

Complete dissociation between atria and ventricle contraction (P waves and QRS)
Atrial signal fails to reach ventricles
Can lead to sudden cardiac death

26

Describe sinus arrhythmia

HR INcreases on INspiration

27

What is left axis deviation?
4 causes

(I +ve, AVF –ve)
• Left bundle branch block (treat w/pacemaker)
• Left ventricular hypertrophy
• Inferior MI
• Wolff-Parkinson White Syndrome

28

Name 5 causes of right axis deviation

• Lateral MI
• Lung consolidation (COPD, PE)
• Right ventricular hypertrophy
• Hyperkalemia
• WPW syndrome

29

How do p-waves change in atrial enlargement?

Spiked in right atrial enlargement, mountains in left atrial enlargement.

30

What can t wave morphology show?

• Flattening/inversion = ischaemia
• Tall, peaked = hyperkalaemia