The hi-tech devices are one of the latest developments under consideration by electronic engineers, said Professor Richard Vincent of Sussex University in Brighton.

Today's most sophisticated pacemakers respond to different levels of activity by sensing when a person is running or moving vigorously.

But while current models judge this by comparing heart rhythms with a baseline established when the device is fitted, the 21st century model would simply have to be told what its owner is up to.

Learning machine

Professor Vincent set out his ideas at the British Association Science Festival in Sheffield.

Advances in technology gives doctors more control over the heart

"What I would envisage is something like a learning phase," he said.

"If someone regularly walks up a hill to the newsagent, for example, the idea might be to say 'I'm going up a hill now' and what would happen is the pacemaker learns that that is the level of exercise that is going on.

"It could then optimise the level of pacemaking for that hill."

Affairs of the heart

Another worthwhile time to have a heart to heart with your pacemaker would be before sex.

"Sex increases the heart rate to about the same degree as going up two flights of stairs," Professor Vincent said.

The technology for computers to recognise voices already exists, but pacemaker development is held up by difficulties in getting enough battery power.

Other advances could improve on even the latest technology, such as the implanted defibrillator, which can reset the heart's rhythm if it goes into a chaotic state known as ventricular fibrillation.

Emergency rescue

But should this system fail, patients are likely to die without immediate attention.

An SOS call sent out by the pacemaker could overcome this problem, and could well be incorporated into future models, Professor Vincent said.

Emergency services might even be able to get a fix on the patient's location by homing in the pacemaker's signal, he said.