A couple whose eldest daughter died from an undiagnosed heart condition a decade ago are calling for a programme of testing to be introduced in schools.
Jenny Legg, from Long Eaton, Derbyshire, was 14 when she died from a heart attack caused by arrhythmia.
Her sister Nicky, now 21, nearly died from the same problem in the same year, now uses a pacemaker.
The family believes routine electrocardiogram testing could save hundreds of lives every year.
Their father Graham also suffers from a form of arrhythmia.
Cardiac arrhythmia, when the heart beats too fast or too slow, affects more than two million people in the UK.
Miss Legg now relies on a pacemaker to make sure her heart is shocked back into rhythm if she suffers from any arrhythmia.
She said: "It means I can live a normal life. I have been to university, I have a job and I can go out with my friends and I can do what I want really because it is like a security blanket I know it is there if I need it."
Mark Lyons, cardiologist physiologist at the City Hospital in Nottingham, said the pacemaker was vital: "It looks out for fast heart rhythms that are potentially life threatening. When it recognises those it delivers a shock to the heart to reset the rhythm."
Miss Legg's family believe a simple electrocardiogram (ECG) test for irregular heart beats should become routine in schools.
"It's the most simple thing to set up and very easy to do and will tell children whether they have this condition or not, " Graham Legg said.
A national campaign is currently under way to encourage people to get to know their pulse rate as a way of detecting problems early on.