see also:

• cardiology
• cardiac arrhythmias
• Narrow Complex Tachycardias and the DDx
• paediatric supraventricular tachycardias (SVT)

see Am. College Card Guidelines on Mx of SVT, RCH guideline - paediatric SVT

• if rapidly deteriorating, then synchronised reversion
• if delay in access to synchronised reversion then:
  • metaraminol (Aramine) 0.5mg iv over 1 minute and repeat minutely until either:
    • arrhythmia reversion
    • max dose 5mg metaraminol given
    • systolic BP > 100

• Valsalva or other vagal manoeuvre (eg. ice on face) may revert a SVT
  • blow into a 10ml syringe with plunger in place then immediately lie flat with legs up in air (REVERT trial suggests this doubles the success rate of just a Valsalva - see vide at bottom)
• IV boluses of adenosine are usually effective with only occasional prolonged AV block but makes patients feel like they are dying.
  • only use with full resuscitative facilities on hand (preferably with external pacing for those rare cases)
  • avoid in severe asthma, patients on theophylline may require higher doses
  • avoid in severe coronary artery disease as risk of vasodilatation of normal vessels may produce ischaemia in vulnerable territory
  • dipyridamole potentiates effects of adenosine
  • carbamazepine increases risk of prolonged AV block
• if adenosine fails and patient is pregnant, then:
  • IV beta blockers such as propranolol, metoprolol or esmolol is next choice, or,
  • DC reversion if necessary as this appears safe in pregnancy
  • ref: Am. College Card Guidelines on Mx of SVT in pregnancy
• alternative to adenosine is IV verapamil (Isoptin) 3mg over 1-2min then 1mg per minute as needed up to 10mg max in adults (unfortunately it seems iv verapamil will be taken off the Australian market in October 2012)
  • BUT ONLY IF:
    • narrow complex tachycardia, and,
    • BP > 80mmHg systolic, and
    • no WPW (as rapid ventricular rate in AF may occur), and
    • not pregnant (greater risk of maternal hypotension and fetal hypoperfusion than adenosine), and
    • take care if ischaemic heart disease or on beta blockers as risk of profound myocardial depression or AV blockade
  • AND ensure you can deal with its adverse effects
• beta blockers may be used as first-line Rx for those with catecholamine-sensitive tachycardias such as RV outflow tachycardia.
• refractory cases should be discussed with cardiology, possible options include:
  • flecainide if young, no structural heart damage on echo, and not pregnant
  • amiodarone
  • sotalol

Postural modification to the Valsalva technique (REVERT trial)