chapter 11 - peri-arrest arrhythmias Flashcards
what are some features of peri-arrest arrhythmias that are indicative of likely deterioration?
shock syncope heart failure myocardial ischaemia extremes of heart rate
why are extreme tachycardias bad?
reduce cardiac output as diastole is very short so the heart has very little time to fill, and reduces coronary blood flow as this occurs mostly during diastole, therefore leading to myocardial ischaemia
describe the adult tachycardia algorithm?
1) assess with abcde approach (give O2, obtain IV access, monitor with ECG, BP etc, identify and treat reversible causes)
2) life threatening features? (shock, syncope, MI, severe heart failure?)
3) if YES -> give synchronised DC shock up to 3 attempts (give sedation if conscious) -> if unsuccessful give amiodarone 300mg IV over 10-20 mins, repeat DC shock
4) if NO -> is the QRS narrow?
5) if QRS is BROAD -> regular or irregular?
5. 5) if irregular -> likely AF with BBB-> treat as narrow irregular OR likely tosades des pointes -> give IV Mg 2g over 10 mins
6) if regular -> if VT give amiodarone (300mg over 10-60mins), if previous certain Dx of SVT with BBB/abberant conduction -> treat as regular narrow complex tachycardia -> if ALL ineffective -> 3x DC shocks
7) if QRS is NARROW -> regular or irregular?
7. 5) if regular -> vagal manouveres -> if ineffective give adenosine 6mg IV bolus, if unsuccessful give 12mg, if unsuccessful give 18mg. -> if ineffective give verapamil or BB -> if ALL ineffective 3x DC shocks
8) if irregular -> probable AF -> control rate with BB, consider digoxin or amiodarone if evidence of HF, anticoagulant if duration >48h
what kind of DC is given in tachyarrhythmias?
synchronised DC -> synchronised shock to the R wave of the QRS (most defibrillators automatically do this)
what would happen if an unsynchronised shock is given in tachycardias?
the shock would likely coincide with the T wave and cause VF
how should you treat regular broad QRS tachycardias?
amiodarone 300mg IV 10-60 mins followed by 900mg maintenance in 24hrs
if it persists despite the initial 300mg then discuss with cardiology consultant on call as DC cardioversion may be needed but with expert advice
what is regular broad QRS tachycardia most likely to be?
VT or SVT - if unsure but definitely regular broad QRS tachycardia then treat as VT
what is irregular broad QRS tachycardia most likely to be?
AF with BBB or polymorphic VT (i.e. torsades)
how should you treat irregular broad QRS tachycardia?
if AF with BB -> treat as narrow irregular tachycardia i.e. rate control with BB, consider digoxin or amiodarone if evidence of HF, anticoagulant if more than 48hrs
if torsades -> stop all medications that prolong QT, correct electrolyte abnormalities, give Mg 2g IV 10 mins, + obtain expert help
what is regular narrow complex tachycardia most likely to be?
1) sinus tachycardia
2) paroxysmal SVT
3) atrial flutter with regular AV conduction (2:1)
Management of regular narrow complex tachycardia?
1) vasovagal manouveres
2) adenosine 6mg, if persists -> 12mg -> 18mg
3) if fails -> verapamil 2n5-5mg IV over 2 mins or BB such as metoprolol
4) if fails -> consider DC cardioversion
if adenosine + vasovagal movers fail then likely to be atrial source and to be AF/atrial flutter -> if recognised on monitor as AF/atrial flutter then treat
what is irregular narrow complex tachycardia most likely to be?
AF with rapid ventricular response (2:1)
Management of irregular narrow complex tachycardia?
rate control - BB
consider digoxin or amiodarone if evidence of HF
anticoagulant if >48hrs
rhythm control with DC cardioversion
what’s the criteria for DC cardioversion of patient who has been in AF for > 48hrs?
Should be anti coagulated for 3 weeks prior to DC cardioversion
IF needed urgently -> LMWH therapeutic dose to be given or heparin infusion
what can be used in management of irregular narrow complex tachycardia if BB contraindicated?
diltiazem
