Bradycardia and Tachycardia Flashcards
Define bradycardia and tachycardia.
Bradycardia = <50 bpm
Tachycardia = >100bpm
What is the approach to brady/tachycardias?
A-E assessment
What investigations are important in brady/tachycardia?
ECG monitoring
BP
SpO2
What are life threatening signs in brady/tachycardias?
Shock
Syncope
MI
HF
What is the next step after A-E in bradycardia with shock?
Atropine 500mcg IV - repeat up to maximum of 3mg if no response
Other than atropine, what other medications may be used to manage bradycardia with shock? What is an alternative to medications?
Isoprenaline -5mcg/min IV
Adrenaline 2-10mcg/min IV
Alternative drugs:
- Aminophylline
- Dopamine
- Glucagon (if BB/CCB overdose)
- Glycopyrrolate
OR transCUTANEOUS pacing
If no medications seem to be working, what is the next step in bradycardia with shock?
Seek expert advice
Arrange transVENOUS pacing
What are some ECG indications for risk of asystole in bradycardia without life threatening signs?
Recent asystole OR
ECG signs: Mobitz II AV block, complete heart block with broad QRS, ventricular pause >3s
How do you manage bradycardia without life threatening signs when there is a risk of asystole?
Same as bradycardia with life threatening features i.e. atropine 500mcg IV or transcutaneous pacing
What categories are the types of tachycardia divided into?
Without life threatening features:
* Broad complex (QRS >0.12s) - regular or irregular
* Narrow complex (QRS <0.12s) - regular or irregular
With life threatening features
What is the management of tachycardia with life threatening signs?
Synchronised DC shock - up to 3 times
+ anaesthesia or sedation if conscious
What is the management of unstable tachycardia if DC shock does not work?
Amiodarone 300mg V over 10-20mins
Repeat synchronised DC shock
Seek expert help
What are the synchronised shock energies for these types of tachycardias?
Broad-complex tachycardia
Atrial fibrillation
Atrial flutter
Regular narrow complex tachycardia
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
What is the management of tachycardia with broad complex?
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
What is the management of stable narrow complex tachycardia?
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
AmiDOWNrone - brings HR down
AtrUPine - brings HR up
If the AF is definitely of <48hrs duration, what is the treatment?
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.
If the AF is of >48hrs duration, what is the treatment?
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.
What is the MOA of atropine?
Anticholinergic/antimuscarinic
Describe the pharmacokinetics of amiodarone (half-life).
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
What are the side effects of long term amiodarone use?
- Slate-grey discolouration of sun-exposed skin
- Corneal microdepositis
- Hypo/hyperthyroidism (contains iodine)
- Pneumonitis
What is the effect of amiodarone on warfarin?
Increases its anticoagulant properties by inhibition of CYP450
How should the amiodarone prescription be written up in paroxysmal AF?
- 200mg TDS for one week,
- then 200mg BD for one week
- then 200mg OD thereafter
What are some causes of sinus bradycardia?
- 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.
