The probe, which is slightly narrower than a straw, has three tiny gems on the tip.
Once it is fed into the heart, through a tiny incision in the groin or wrist, the diamonds are heated up to about 70c. This destroys the rogue heart cells that are causing the faulty rhythms, and which may lead to a condition called atrial fibrillation (AF).
More than one million people in the UK have AF, which develops when electrical activity in the heart goes haywire and causes it to beat irregularly.
This can result in chest pain, dizziness and fatigue. But a significant number of those affected have no idea they are ill until they have a stroke.