Arrhythmias Flashcards
What is an arrhythmia?
-Abnormal heart rhythms
-result from an interruption to the normal electrical signals of contraction
What are the four cardiac arrest rhythms ?
shockable: ventricular tachycardia, ventricular fibrillation
non shockable: pulseless electrical activity, asystole
How do we treat tachycardia briefly ?
Unstable patient:
Consider up to 3 synchronised shocks
Consider an amiodarone infusion
In a stable patient:
Narrow complex (QRS < 0.12s)
Atrial fibrillation – rate control with a beta blocker or diltiazem (calcium channel blocker)
Atrial flutter – control rate with a beta blocker
Supraventricular tachycardias – treat with vagal manoeuvres and adenosine
Broad complex (QRS > 0.12s)
Ventricular tachycardia or unclear – amiodarone infusion
If known SVT with bundle branch block treat as normal SVT
If irregular may be AF variation – seek expert help
What is atrial flutter and how is it treated?
the electrical signal goes round and round the atrium instead of going through AV node to ventricles
Treated by controlling rate with beta blockers, radio frequency ablation or anticoags
What is SVT and what are the three main types ?
- electrical signal going back into the atrium from the ventricles through the AV node.
- “Atrioventricular nodal re-entrant tachycardia” is when the re-entry point is back through the AV node.
“Atrioventricular re-entrant tachycardia” is when the re-entry point is an accessory pathway (Wolff-Parkinson-White syndrome).
“Atrial tachycardia” is where the electrical signal originates in the atria somewhere other than the sinoatrial node. this is abnormally generated atrial activity not a signal from the ventricles
How do we manage stable SVT?
- continuous ECG monitoring
- Valsalva - blowing hard into syringe
- Carotid sinus massage- massage carotid on one side with two fingers
-Adenosine
-verapamil (calcium channel blocker) - direct current cardioversion if treatment fails
How does adenosine work?
- slowing cardiac conduction through AV node to reset it back to sinus rhythm
- given as rapid bolus - so that there is enough impact to interrupt the AV node/ accessory pathway
- avoid patient with asthma
- warn about feeling of dying
-fast IV bolus in a large proximal canula
How do you long term manage paroxysmal SVT patients?
Paroxysmal SVT describes a situation where SVT reoccurs and remits in the same patient over time.
medication: Medication (beta blockers, calcium channel blockers or amiodarone)
Radiofrequency ablation
What is wolf-parkinson white syndrome ?
- extra electrical pathway connecting atria and ventricles
-treatment- radiofrequency ablation of accessory pathway.
ECG Changes:
Short PR interval (< 0.12 seconds)
Wide QRS complex (> 0.12 seconds)
“Delta wave” which is a slurred upstroke on the QRS complex
How does radiofrequency ablation occur?
- catheter ablation performed, inserting catheter into femoral veins and feeding it through venous system
-placed in different heart areas to test signals
-radiofrequency ablation (heat) is applied to burn the abnormally active area - leaves scar tissue
What is torsades de pointes?
- type of polymorphic ventricular tachycardia
- has prolonged QT interval
- which is prolonged repolarisation
- longer repolarisation can cause spontaneous depolarisation in some areas of heart myocytes -> causing ventricular contraction before proper repolarisation
What are the causes of prolonged QT?
- long QT syndrome
- medication e.g antipsychotics, citalopram, flecainide, sotalol, amiodarone, macrolide antibiotics
- electrolyte disturbance- hypokalaemia, hypomagnesaemia, hypocalcaemia
What is the acute management of Torsades de pointes
Correct the cause (electrolyte disturbances or medications)
Magnesium infusion (even if they have a normal serum magnesium)
Defibrillation if VT occurs
What is the long term management of prolonged QT syndrome?
Avoid medications that prolong the QT interval
Correct electrolyte disturbances
Beta blockers (not sotalol)
Pacemaker or implantable defibrillator
What is a ventricular ectopic ?
- premature ventricular beats
- cause: random electrical discharges outside of atria
-when they occur so frequently its after every sinus beat then it is Bigeminy
