Question 7

College Answer

Pulseless VT: managed as per cardiac arrest protocol (immediate unsyncbronised defibrillation [up to 3 sequential  shocks  if  necessary],  followed  by CPR  intubation/IV/oxygen, consider antiarrhythmics  (lignocaine, amiodarone, potassium and magnesium], administer  adrenaline 1 mg every 3 minutes, exclude reversible causes [5Hs and 5Ts].

VT with a pulse: if deteriorates or unstable haemodynamically manage as for pulseless VT.If stable administer  oxygen/obtain  IV  access  and  rapidly  exclude  reversible  factors  (including   wire catheter in RV, hypokalaemia,  hypomagnesaemia, others  as indicated  by a systematic  review to exclude  other  reversible  causes.  Drug  therapy  according  to  scenario  but  useful  drugs include lignocaine (for ischaemia/post  cardiac surgery: 1-1.5  mg/kg IV then infusion), procainamide  (50 mglmin to max of 17 mglk.g),sotalol (l mglkg) or amiodarone (5 mg/kg over 20 minutes).

Discussion

The question draws on the candidate's knowledge of recent resuscitation guidelines.

The ARC has a pretty straightforward view of these sort of tachyarrhythmias. If it is hemodynamically usntable, you shock it. If it is haemodynamically stable, you can afford to think about drugs. If it is without pulse, the patient is dead and you should proceed according to the ALS algorithm for shockable rhythms (nowadays we dont do those three shocks anymore).

Thus:

• Acute management:
  • VT with pulse:
    • haemodynamically stable:
      • control arrhythmia with antiarrhytmic medications
      • Amiodarone is now the preferred agent (ARC guideline 11.9, 2009)
      • 300mg amiodarone over 20-60 minutes, followed by an infusion of 900mg over 24 hrs
      • Class 1a agents like lignocaine are a reasonable alternative, particularly if the QT interval is prolonged.
    • Haemodynamically unstable:
      • Synchronised cardioversion
      • If this does not work, give 300mg amidoarone over 10-20min, and then attempt cardioversion again
      • Follow this with 900mg amiodarone over 24 hours.
  • Pulseless VT:
    • consider a praecordial thump
    • commence CPR
    • progress according to ILCOR ALS algorithm for shockable rhythms
• Prevention of recurrence:
  • correct electrolyte disturbance
  • rule out cardiac ischaemia as cause
  • cease arrhythmogenic medications
  • address mechanical causes of VT: for example, PA catheter or very low CVC tips

Pellegrini, Cara N., and Melvin M. Scheinman. "Clinical management of ventricular tachycardia." Current problems in cardiology 35.9 (2010): 453-504.

Hazinski, Mary Fran, et al. "Part 1: Executive Summary 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations." Circulation 122.16 suppl 2 (2010): S250-S275.