CARDIOVERTER

Typical Number in Hospital: 15

Cost Bands: 3,6

References:

Cardioversion is the correction of abnormal rhythms of the heart using a defibrillator which can be made to present its current pulse at a particular time in the cardiac cycle. They are used mainly in the coronary care unit for correcting atrial fibrillation.

The device consists of a defibrillator and an ECG monitor working through normal ECG electrodes, or detecting the ECG through the defibrillator paddles. The R wave of the ECG is identified by the monitoring circuit and used to create a triggering pulse for the defibrillator at a set (by the operator) time in the cardiac cycle.

Since cardioversion is used in circumstances where the heart is still pumping (albeit imperfectly) some skill is required to prevent the defibrillating pulse from causing fibrillation due to incorrect timing or excessive currents.

Many defibrillators intended for emergency use in cases of ventricular fibrillation also have a synchronizing facility. It is most important that the machine defaults to the asynchronous mode so that the synchronizing circuit is not used in cases of ventricular fibrillation. The use of synchronous defibrillation during ventricular fibrillation may result in failure to deliver any current, since no R wave would be detected.