Tuesday, November 30, 2010

Cardiac Arryhtmias



Type
Management
Cardiac Arrest
–Shockable
•VF, Pulseless VT
–Non Shockable
•Asystole, PEA
Shockable or non-shockable?
Resume CPR immediately after the shock when IV/IO available, give vassopressor during CPR (before or after the shock)
Epinephrine 1mg IV/IO repeat every 3-5 min or
1 dose of vasopressin 40U IV/IO to replace first or second dose of epinephrine
Note that by this time, if 3rd shock is required, it is the DRUG →SHOCK→ CPR sequence. It is the same sequence thereafter
After the 3rd sequence and giving adrenaline/vasopressin, consider giving antiarrhythmics like amiodarone for VF or magnesium for torsades de pointes. The sequence is still the same DRUG→SHOCK→ CPR. At any time, if rhythm becomes non-shockable, follow the non-shockable algorithm
•Peri arrest rhythms
–Tachyrrhythmias
–Bradyarrhythmias
2nd degree Mobitz type 1
•the block is at AV Node
•Often transient
•Maybe asymptomatic
2nd degree Mobitz type 2
•Block most often below AV node, at bundle of His or BB
•May progress to 3rd degree AV block
Four Rhythms At Risk Of Developing Asystole
1.Recent asystole
2.Mobitz II 2nd degree AV Block
3.Complete Heart Block (especially with broad QRS or initial heart rate <40/min)
4.Ventricular standstill more than 3 sec
Stable or not stable?
Four main signs
1.Signs of low cardiac output – systolic hypotension < 90 mmHg, altered mental status
2.Excessive rates: <40/min or >150/min
3.Chest pain
4.Heart failure
•If unstable, electrical therapy: cardioversion for tachyarrhythmias, pacing for bradyarrhythmias
Atropine 0.5 mg each bolus up to 3 mg. Atropine as temporizing measure only.
Needs transcutaneous/transvenous pacing
For polymorphic VT – if patients become unstable, perform defibrillation rather than cardioversion. If ever in doubt whether to perform cardioversion or defibrillation, then perform DEFIBRILLATION
Rule of thumb – if your eye cannot synchronize to each QRS complex, neither can the machine!
•For stable tachyarrhythmias, we need to further decide whether it is NARROW QRS or WIDE QRS
•For each type, further divide into
–Regular
Irregular
Narrow QRS tachyarrhythmias
–Regular
•Sinus Tachycardia, PSVT, atrial flutter with regular AV conduction
–Irregular
•Atrial Fibrillation, Atrial flutter with variable AV Block
Wide (Broad) QRS tachyarrhythmias
–Regular
•Ventricular Tachycardia, SVT with BBB
–Irregular
Polymorphic VT, AF with BBB
Narrow complexes and regular – attempt vagal maneuver and adenosine;
Narrow complexes but not regular- likely AF. Don’t give adenosine.  May attempt rate control using beta blocker or diltiazem
Amiodarone can be given for both regular and irregular broad complexes

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