Bradycardia and Tachycardia

Question 1

Define bradycardia and tachycardia.

Answer 1

Bradycardia = <50 bpm
Tachycardia = >100bpm

Question 2

What is the approach to brady/tachycardias?

Answer 2

A-E assessment

Question 3

What investigations are important in brady/tachycardia?

Answer 3

ECG monitoring
BP
SpO2

Question 4

What are life threatening signs in brady/tachycardias?

Answer 4

Shock
Syncope
MI
HF

Question 5

What is the next step after A-E in bradycardia with shock?

Answer 5

Atropine 500mcg IV - repeat up to maximum of 3mg if no response

Question 6

Other than atropine, what other medications may be used to manage bradycardia with shock? What is an alternative to medications?

Answer 6

Isoprenaline -5mcg/min IV
Adrenaline 2-10mcg/min IV
Alternative drugs:

• Aminophylline
• Dopamine
• Glucagon (if BB/CCB overdose)
• Glycopyrrolate

OR transCUTANEOUS pacing

Question 7

If no medications seem to be working, what is the next step in bradycardia with shock?

Answer 7

Seek expert advice
Arrange transVENOUS pacing

Question 8

What are some ECG indications for risk of asystole in bradycardia without life threatening signs?

Answer 8

Recent asystole OR
ECG signs: Mobitz II AV block, complete heart block with broad QRS, ventricular pause >3s

Question 9

How do you manage bradycardia without life threatening signs when there is a risk of asystole?

Answer 9

Same as bradycardia with life threatening features i.e. atropine 500mcg IV or transcutaneous pacing

Question 10

What categories are the types of tachycardia divided into?

Answer 10

Without life threatening features:
* Broad complex (QRS >0.12s) - regular or irregular
* Narrow complex (QRS <0.12s) - regular or irregular

With life threatening features

Question 11

What is the management of tachycardia with life threatening signs?

Answer 11

Synchronised DC shock - up to 3 times
+ anaesthesia or sedation if conscious

Question 12

What is the management of unstable tachycardia if DC shock does not work?

Answer 12

Amiodarone 300mg V over 10-20mins
Repeat synchronised DC shock
Seek expert help

Question 13

What are the synchronised shock energies for these types of tachycardias?
Broad-complex tachycardia
Atrial fibrillation
Atrial flutter
Regular narrow complex tachycardia

Answer 13

Broad-complex tachycardia - 120-150J biphasic; increase if this fails
Atrial fibrillation - start at maximum setting
Atrial flutter or regular narrow complex tachycardia - both 70-120J; increase if fails

Question 14

What is the management of tachycardia with broad complex?

Answer 14

Irregular
* If AF with BBB - treat as for irregular narrow complex
* Polymorphic VT (e.g. torsades de pointes) - magnesium 2g over 10mins

Regular
* **Assume VT **- amiodarone 300mg IV over 10-60mins then 24hr infusion
* If prev confirmed SVT with BBB/aberrant conduction - treat as for **regular **narrow complex tachycardia
* If ineffective –> 3 synchronised DC shocks + anaesthesia/sedation if conscious

Question 15

What is the management of stable narrow complex tachycardia?

Answer 15

Irregular: probably AF
* Rate control - BB
* +/- digoxin or amiodarone - if evidence of HF
* +/- anticoagulate - if duration >48hrs

Regular
1. Vagal maneouvres
2. If ineffective –> adenosine 6mg rapid IV –> 12mg –> 18mg (monitor ECG throughout)
3. If ineffective consider atrial flutter –> verapamil or BB
4. If ineffective –> synchronised DC shock up to 3 times + anaesthesia/sedation

Question 16

AmiDOWNrone - brings HR down

Answer 16

AtrUPine - brings HR up

Question 17

If the AF is definitely of <48hrs duration, what is the treatment?

Answer 17

Heparin
Electrical or chemical cardioversion:
* Electrical - DC cardioversion
* Chemical - amiodarone (in structural HD), flecainide/amiodarone (in no structural HD)

If risk of stroke: lifelong oral anticoagulation. Unless confirmed that the AF only lasted <48hrs.

Question 18

If the AF is of >48hrs duration, what is the treatment?

Answer 18

Anticoagulate for 3 weeks then consider cardioversion*
OR TOE to exclude left atrial appendage thrombus and cardiovert immediately

THEN anticoagulate for 4 weeks post-cardioversion.

NB: If there is high risk of DC cardioversion failure (e.g. it has failed before) give amiodarone/sotalol for 4 weeks prior.

Question 19

What is the MOA of atropine?

Answer 19

Anticholinergic/antimuscarinic

Question 20

Describe the pharmacokinetics of amiodarone (half-life).

Answer 20

Amiodarone has:
* Large volume of distribution
* Long half-life.
* Steady-state levels are not achieved for several months so a loading dose is required on initiation

Question 21

What are the side effects of long term amiodarone use?

Answer 21

• Slate-grey discolouration of sun-exposed skin
• Corneal microdepositis
• Hypo/hyperthyroidism (contains iodine)
• Pneumonitis

Question 22

What is the effect of amiodarone on warfarin?

Answer 22

Increases its anticoagulant properties by inhibition of CYP450

Question 23

How should the amiodarone prescription be written up in paroxysmal AF?

Answer 23

• 200mg TDS for one week,
• then 200mg BD for one week
• then 200mg OD thereafter

Question 24

What are some causes of sinus bradycardia?

Answer 24

• Normal in athletes
• Hypothermia
• Hypothyroidism
• Vagal stimulation
• Drugs (e.g. beta blockers)
• Raised intracranial pressure
• Myocardial infarction.
• Infections including Legionnaire’s disease, typhoid fever and Lyme disease.