c_svt

supraventricular tachycardias (SVT)

acute reversion of paroxysmal SVT:

haemodynamically unstable

  • 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

haemodynamically stable

  • 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:
  • 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:

Postural modification to the Valsalva technique (REVERT trial)

c_svt.txt · Last modified: 2015/08/30 22:23 by gary1