Suspected heart attack victims at a high-security jail are being diagnosed over the phone instead of in hospital.
The move has cut the number of inmates leaving jail to visit hospital
Managers at Wakefield Prison, which houses some of England's most notorious criminals, say the move has improved public safety and cut costs.
A hand-held electrocardiogram (ECG) device sends a signal by landline to a monitoring centre, where it is shown on a screen and interpreted by clinicians.
The results are given verbally over the phone and followed up with an email.
People experiencing heart problems would normally receive an ECG at hospital.
But the hand-held ECG can be used by people who are not health professionals, according to the makers, Broomwell HealthWatch.
A spokesman said that the "telemedicine" device was already used on oil rigs, where remote diagnosis was essential.
Wakefield Prison, where Soham killer Ian Huntley is an inmate, has been piloting the system over the last 12 months.
The jail says its success has prompted interest from other prisons around the country.
HMP Wakefield has an above average population of elderly inmates serving life sentences and has used the device two or three times a month since introducing it a year ago.
Brian Almand, clinical manager at the jail said: "We recognised we had a problem with the number of elderly prisoners, which is why we took this on.
"By eliminating unnecessary hospital visits for ECG examination, we've not only improved public safety, but also achieved significant cost savings.
"It has reduced the need for prisoner transport and prison officer escorting costs, especially on night-time call-outs, which used a lot of resources."
The hand-held ECG device is sold for about £300, with each telephone diagnosis costing £20.
A Broomwell HealthWatch spokesman said it cost the NHS £100 to perform an ECG.