Arrythmias Flashcards
What are the shockable rhythms?
Ventricular fibrilation
Pulseless ventricular tachycardia
What are the non shockable rhythms?
Asystole
Pulseless electrical activity
If any adverse signs are present in a patient with tachyarrhythmia, what should be done?
- Up to 3 synchronised DC shocks (+ sedation if conscious) with continued CPR 30:2 in-between
- Amiodarone 300mg IV over 10-20 mins
- Repeat synchronised DC shock
List 4 adverse signs indicating a patient with an arrhythmia is unstable
Shock: hypotension, pallor, sweating, cold extremities, confusion, impaired consciousness
Syncope
Myocardial ischaemia
Heart failure
When assessing a tachyarrythmia, what should you consider?
Wide or Narrow complex?
Regular or Irregular
P waves present? Normal or abnormal?
List 5 causes of narrow complex tachycardia
Atrial fibrilation
Atrial flutter
Sinus tachycardia
AV nodal re-entry tachycardia
AV re-entry tachycardia
(SVTs: AF, atrial flutter, AVNRT, AVRT)
List 3 causes of broad complex tachycardia
Ventricular tachycardia
Supraventricular tachycardia with aberrancy e.g. BBB
Supraventricular tachycardia with pre-excitation e.g. WPW
What should be assumed about the origin of the tachyarrythmia unless proven otherwise?
Narrow: supraventricular tachycardias
Broad: ventricular tachycardias
How can you tell a beat is sinus in origin?
Normal p wave
Normal (narrow) QRS
How can you tell a beat is atrial in origin?
Abnormal p wave
Normal (narrow) QRS
How can you tell a beat is junctional (AVN) in origin?
p wave absent (buried)
or
Abnormal p wave just before/ after QRS
Narrow QRS
How can you tell a beat is ventricular in origin?
Wide QRS, abnormal T waves
No p wave
List 3 most common causes of a regular narrow complex tachycardia
Sinus tachycardia
Atrial flutter
Re-entrant SVT
List 4 symptoms of SVTs
Palpitations
Chest pain
Anxiety
SOB
Describe management of regular narrow complex tachycardia
- Vagal manœuvre: Valsalva
- Adenosine 6mg IV
- Adenosine 12mg IV
- Adenosine 18mg IV
- DC cardioversion (if above fail/ haemodynamically unstable)
What is the valsalva manœuvre?
Forced expiration against a closed glottis
Ask patient to try to blow plunger back on 20ml syringe
List 5 side effects of adenosine
Nausea
Dizziness
Breathlessness
Chest tightness
Flushing
Name 2 drugs that interact with adenosine
Dipyridamole (antiplatelet agent): enhances effects of adenosine
Theophylline: blocks effects of adenosine
Describe the MOA of adenosine
Causes transient heart block in the AV node
Agonist of A1 receptor in AVN, which inhibits adenylyl cyclase; reducing cAMP + causing hyperpolarization by increasing outward K+ flux
V short half-life: 8-10s
How should adenosine be administered? Why?
Infused via a large-calibre cannula due to it’s short half-life
In which patients is adenosine contraindicated? What drug is preferred?
Asthmatics (may cause bronchospasm)
Verapamil 5-10mg IV
What is the long term management for patients with SVT due to AVNRT?
Educate on vagal manoeuvres
B-blockers
Catheter ablation
Give 4 ECG features of atrial fibrillation
Irregularly irregular rhythm
No p waves
Unstable baseline
Narrow QRS complexes
What is the probable cause of an irregular narrow complex tachycardia?
AF
Describe acute management of atrial flutter
Similar to AF although medication may be less effective
Flutter is more sensitive to cardioversion so lower energy levels may be used
Describe long term management for atrial flutter
Radiofrequency ablation of Tricuspid valve isthmus
What are the types of ventricular tachycardia?
Monomorphic VT: all QRS complexes about the same size
Polymorphic VT (TdP): changing QRS amplitude
Give 4 indicators of VT
AV dissociation
Fusion beats
Capture beats
Extreme axis deviation
Describe management of Torsades de pointes
Magnesium sulfate 1-2g IV
Describe treatment of broad complex tachycardias
In haemodynamically stable patients
- Amiodarone 300mg IV over 10-60 mins
- DC Cardioversion
Give 2 alternatives to amiodarone in management of broad complex tachycardia
Lidocaine: use with caution in severe LV impairment
Procainamide
What is the long term management for ventricular tachycardia?
Implantable cardioverter defibrillator
+/or B-blockers / Sotalol
What is the class and MOA of Amiodarone?
Class III antiarrhythmic agent
Blocks K+ channels which inhibits repolarisation + hence prolongs the action potential.
Also has other actions such as blocking Na+ channels (a class I effect)
What effect does Amiodarone have on the p450 enzyme system?
p450 inhibitor e.g.
Decreases metabolism of warfarin
Give 2 limiting factors to the way in which amiodarone is administered
V long half-life (20-100 days). For this reason, loading doses are frequently used
Ideally given into central veins (causes thrombophlebitis)
What ECG changes may be caused by amiodarone?
Lengthens QT (proarrhythmic effect)
Bradycardia
What are the monitoring requirements for amiodarone?
Prior to Tx: TFT, LFT, U&E, CXR
Every 6 months: TFT, LFT
What alternative drugs can be given second line in management of bradycardia?
Isoprenaline/ Adrenaline infusion
List 8 adverse effects of amiodarone
Thyroid dysfunction: both hypo + hyper-thyroidism
Corneal deposits
Pulmonary fibrosis/ pneumonitis
Liver fibrosis/ hepatitis
Peripheral neuropathy, myopathy
Photosensitivity
‘Slate-grey’ appearance
Thrombophlebitis + injection site reactions
What is the treatment for all patients with bradycardia?
- Atropine 500mcg IV
- Atropine 500mcg IV repeat to max 3mg
- Transcutaneous pacing
- Transvenous pacing
Give 4 risk factors for deterioration of bradycardia to asystole
Complete heart block with broad complex QRS
Recent asystole
Mobits type II AV block
Ventricular pause >3s
