Chapter 11 Flashcards
(7 cards)
What are the life threatening features in an arrhythmia?
Shock - SBP less than 90
Syncope
Severe heart failure
Myocardial ischaemia
Extremes of heart rate over 150 or under 40
How should tachyarrhythmia be managed if there are adverse features?
Synchronised DC shock under sedation or general anaesthesia
For broad complex start at 120-150J and increase in increments if this fails
For atrial fibrillation start at maximum defib output
Atrial flutter and narrow complex tachys can use lower energy 70-120J
For atrial fibrillation and flutter use anteroposterior pad position
Deliver shock and keep button pressed until shock delivered
How to manage tachyarrhythmia if no life threatening features
Assess QRS duration
Broad complex - determine if regular or irregular
Regular (VT or supraventricular with bundle branch block) - treat with amiodarone 300mg IV over 10-60 minutes followed by 900mg over 24 hours. If persists after initial 300mg, can consider synchronised cardioversion (expert decision)
Irregular (likely to be AF with BBB, AF with pre-excitation or polymorphic VT) - if polymorphic VT correct electrolytes, stop QT prolonging drugs, give magnesium 2g over 10 minutes. If known AF with BBB treat as for irregular narrow complex.
Narrow - determine if regular or irregular
Regular (SVT, atrial flutter with regular AV conduction) - vagal manoeuvres (carotid sinus massage, Valsalva), if persistant and not atrial flutter give adenosine 6mg bolus with flush, give 12mg if no response then 18mg. If adenosine fails consider verapamil 2.5-5mg IV over 2 minutes or a beta blocker e.g. metoprolol (2.5-15mg in 2.5mg boluses). If persists consider synchronised cardioversion.
Irregular (AF with RVR) - rate control with beta blocker, chemical cardioversion if less than 48 hours onset with digoxin if heart failure, amiodarone, flecainide (if no heart failure/structural heart disease/ischaemic heart disease), synchronised cardioversion if less than 48 hours onset. Start anticoagulation at the earliest opportunity (LMWH/UFH then DOAC) if cardioversion required, if onset more than 48 hours and can delay cardioversion should be anticoagulated for 3 weeks.
How is bradyarrhythmia with life threatening features managed?
Treat with atropine 500mcg IV, repeat every 3-5 minutes to a maximum of 3mg. Use cautiously in acute MI
Second line options for drug therapy - isoprenaline 5mcg/min IV, adrenaline 2-10mcg/min IV, dopamine 2.5-10mcg/kg/min IV.
If persists despite atropine consider pacing. If pacing unavailable give second line drug.
Consider glucagon if beta blocker or calcium channel blocker cause of bradycardia.
If life-threatening severe brady and pacing not available can use percussion pacing as an interim measure.
How to manage bradyarrhythmia without adverse features
Monitor
Assess for cause of brady
How should rapid narrow complex tachycardia with no pulse be managed?
Treat as PEA - start CPR
May be treatable with shock - give synchronised shock
How to treat bradycardia cause by acute inferior MI, spinal cord injury or cardiac transplant?
Consider aminophylline (100-200mg by slow IV injection)
Don’t give atropine to cardiac transplants
