Three patients from East Sussex are the first in the country to be fitted with a new "intelligent" pacemaker.
The digital pacemaker can adapt to fluctuating heartbeats
The digital unit, which is being tested at Eastbourne District General Hospital, can adapt to a fluctuating heartbeat, unlike current models.
It is the same weight as existing pacemakers but has a memory which makes it able to record a patient's heartbeats over an entire year.
This data makes it easier for doctors to monitor the performance of a heart.
The device, which is the same size as a £2 coin, is revolutionary as it is able to "think for itself".
It does this by detecting any changes in the heart rate and adapting to the new rhythm.
Consultant cardiologist Neil Sulke said that, unlike current models which just count heartbeats, the digital unit provides a more complete picture by recording information about any irregularities.
"It can look at the heartbeat in much more detail and allow it to learn and become an 'intelligent' pacemaker," he said.