Arrhythmias Flashcards
Shockable rhythms
Ventricular tachycardia
Ventricular fibrillation
Non-shockable rhythms
Pulseless electrical activity
Asystole
Narrow complex tachycardias
Atrial fibrillation
Atrial flutter
Supraventricular tachycardia
Broad complex tachycardias
Ventricular tachycardia
SVT with bundle branch block
Treatment of stable AF
Rate control with beta blocker or diltiazem
Treatment of stable atrial flutter
Rate control with beta blocker
Treatment of stable SVT
Vagal manouevres and adenosine
Treatment of stable VT
Amiodarone infusion
Treatment of stable known SVT with BBB
Treat as normal SVT
Atrial flutter
Re-entrant rhythm where electrical signal re-circulates in self-perpetuating loop due to an extra pathway
Atrial contraction rate in atrial flutter
300bpm
Ventricular contraction rate in atrial flutter
150bpm
Signal makes its way into ventricles every second lap due to long refractory period in AV node
Conditions associated with atrial flutter
HTN
IHD
Cardiomyopathy
Thyrotoxicosis
Management of atrial flutter
Rate/rhythm control with beta blockers or cardioversion
Treat reversible underlying cause
Radiofrequency ablation of re-entry rhythm
Anticoagulation based on CHA2DS2VASc score
SVT
Electrical signal re-entering atria from the ventricles
Once signal is back in the atria it travels back through AV node and causes another ventricular contraction
Types of SVT
Atrioventricular nodal re-entrant tachycardia- re-entry point through AV node only
Atrioventricular re-entrant tachycardia- re-entry point is accessory pathway (WPW)
Atrial tachycardia- signal originates in atria somewhere other than sinoatrial node
Adenosine action
Slows cardiac conduction through AV node
Resets back to sinus rhythm
Needs to be given as rapid bolus
Adenosine contraindications
Asthma
COPD
HF
Heart block
Severe hypotension
Adenosine warnings
Causes brief asystole/ bradycardia
Scaring feeling of dying/ impending doom
Adenosine dosing
6mg then 12mg then 12mg if no improvement between doses
Long term management of paroxysmal SVT
Beta blockers, calcium channel blockers, amiodarone
Radiofrequency ablation
Wolf parkinson white syndrome
Extra electrical pathway connect atria and ventricles (often called bundle of Kent)
WPW ECG changes
Short PR interval
Wide QRS complex
Delta wave (slurred upstroke on QRS complex)
Definitive management of WPW
Radiofrequency ablation
Torsades de pointes
Polymorphic ventricular tachycardia
Height of the QRS complex progressively gets smaller then larger etc
Causes of prolonged QT
Long QT syndrome (inherited)
Medications (antipsychotics, citalopram, flecanide, sotalol, amiodarone, macrolides)
Electrolyte disturbances (hypokalaemia, hypomagnesaemia, hypocalcaemia)
Acute management of torsades de pointes
Correct the cause
Magnesium infusions (even if normal serum magnesium)
Defibrillation of VT occurs
Longterm management of prolonged QT syndrome
Avoid medications that prolong QT interval
Correct electrolyte imbalances
Beta blockers (not sotalol)
Pacemaker or implantable defibrillator
Ventricular ectopics
Premature ventricular beats caused by random electrical discharges from outside the atria
Bigeminy
Ventricular ectopics are occurring so frequently that they happen after every sinus beat
ECG looks like normal sinus beat followed immediately by an ectopic, then normal, then ectopic etc
Management of ventricular ectopics
Check bloods for anaemia, electrolyte disturbances and thyroid abnormalities
Reassurance and no treatment if otherwise healthy
First degree heart block
Delayed AV conduction
Every atrial impulse leads to ventricular contraction
Second degree heart block
Some atrial impulses do not make it through AV node
Instances where p waves do not lead to QRS complexes
Mobitz type 1 (Wenckebach’s)
Atrial impulses become gradually weaker until doesn’t pass through AV node
Increasing PR interval and then drops P wave
Mobitz type 2
Intermittent failure or interruption of AV conduction
Usually set ratio of p waves to QRS complexes
PR interval remains normal
Risk of asystole
2:1 block
2 p waves for each QRS complex
Every second p wave is not strong enough to stimulate a QRS complex
Third degree heart block
Complete heart block
No observable relationship between p waves and QRS
Significant risk of asystole
1st line treatment for unstable bradycardias/ AV node blocks
Atropine 500mcg IV
Treatment for unstable bradycardias if no improvement
Atropine 500mcg repeated (up to 6 doses)
Other inotropes (such as noradrenaline)
Transcutaneous cardiac pacing
Treatment if patients high risk of asystole (Mobitz 2, complete heart block)
Temporating transvenous cardiac pacing
Permanent implantable pacemaker
Atropine action
Antimuscarinic medication
Inhibits the parasympathetic nervous system
Atropine side effects
Pupil dilatation
Urinary retention
Dry eyes
Constipation
