Ventricular Tachycardia (VT) arises from enhanced automaticity of an area of ventricular myocardium, often mediated by an ischaemic substrate.

There are specific patient populations who are at significantly higher risk of these arrhythmias, either because of prior documented episodes, or because of the underlying substrate of their cardiac disease.

In these cases, it is important to provide primary or secondary prevention with a device capable of detecting, and hopefully successfully treating, VF or VT.

One of the major advances in ICD technology has been the development of devices capable of detecting, and terminating VT, through the use of overdrive pacing. Rapid pacing at a rate slightly faster than the VT aims to ‘capture’ the ventricle, and leads to termination of the arrhythmia when pacing stops (Fig 1). This requires effective detection and discrimination of VT from other tachycardias.

Fig 1  Anti-Tachycardia Pacing (ATP) electrogram. Click the image to see a larger version. Image reproduced with permission from Boston Scientific