By: Martin Grant Student no

 Cardioversion is defined as a “synchronised direct current (DC) discharge, and … does not apply to ventricular defibrillation or to the pharmacologic reversion of arrhythmias.”  It is synchronised to give electrical discharge at the point of the Q or R wave in the ECG cycle.  The reason to synchronise this is to prevent a shock occurring during repolarisation of ventricles in the T wave, which can lead to Ventricular Fibrillation.

Left shows the various waves throughout the ECG and explains what each deflection means from the isoelectric line. Right shows another ECG but with colour demonstrates the duration of each different segment. Fig 1 Fig 2

 Based on advanced cardiac life support (ACLS) guidelines, any patient with narrow or wide QRS complex tachycardia (ventricular rate >150) who is unstable (for example, chest pain, pulmonary oedema, lightheaded, hypotension) should be immediately treated with synchronized electrical cardioversion.

 Supraventricular tachycardia due to re-entry  Atrial fibrillation  Atrial flutter  Atrial tachycardia  Monomorphic VT with pulsesContraindications  Digoxin toxicity–associated tachycardia  Sinus tachycardia caused by various clinical conditions  Multifocal atrial tachycardia

 Midaxillary line Right Sternal edge Intercostal spaces

 First of all, the appropriate equipment must be organised: ◦ IV access ◦ Airway management equipment ◦ Sedative drugs (midazolam and fentanyl) ◦ Cardioversion monitoring device

 Place patient onto bed  Remove upper garments  Apply heart tracing leads Conduction strips Points of application Leads: Red, Amber, Green (Traffic lights)

 Turn the Cardioversion machine on Twist green nozzle clockwise to activate Off

 Place on the pads Pads and connection for machine First pad: 2 nd or 3 rd intercostal space, Right Sternal edge Second pad: 4 th or 5 th Intercostal space, Midaxillary line Anterolateral pad positioning

 Check heart tracing is being picked up

 Press Sync to locate R waves R waves indicated by arrows

 Set the voltage as per guidelines on the condition presenting with the patient

 WARN EVERYBODY AROUND THE BED YOU ARE ABOUT TO PRESS CHARGE AND SHOCK  Everyone should step back from the patient and the bed

 Press Charge  Then Shock

 Watch the monitor and see if the Rhythm has returned to normal  If not, this may need to be repeated  Below is a before and after ECG from a patient in AAH with Supraventricular tachycardia resolved using Synchronised DC Cardioversion

 Synchronised cardioversion when practiced correctly can be a very effective way to correct tachycardia’s.  ACLS guidelines should be followed for when it should be used and at which voltage.  Always check for the contraindications prior to the procedure.  Follow the steps above for the correct way to perform the procedure safely and effectively.

1. Lown B. Defibrillation and cardioversion. Cardiovasc Res. Aug ;55(2): [Guideline] Part 5: Electrical Therapies. Automated External Defibrillators, Defibrillation, Cardioversion, and Pacing. Circulation. 2005;112:IV-35-IV-46.Figures 1. astr.gsu.edu/hbase/biology/imgbio/ecg.gif