Friday, 10 September 2010

MRCP revision battle 7.5: broad complex tachycardia

At some point an ECG will be shoved under your nose which shows an unnerving broad complex pattern going at a fast rate.  If in doubt, these must always be regarded as VT.  However, there are a few less scary possibilities, such as:
  • AF with LBBB
  • orthodromic tachycardic WPW
  • ventricular paced rhythm

Essentially the main call is whether the broad complex tachycardia is superventricular or ventricular in origin, and the features the MRCP exam expects you to pick up on to differentiate these two are:

  • AV dissociation - suggests VT
  • fusion/capture beats - suggest VT
  • positive QRS concordance in chest leads - suggests VT
  • marked left axis deviation - suggests VT
  • history of IHD - more likely VT
  • QRS>140ms - suggests VT
  • no response to adenosine/massage - suggests VT

Well thats if for today.  A quick test of yesterdays topics is available here if you still have the energy.