Lives will be saved through a generous legacy left to the ambulance service by a former patient from St Neots.
The £135,000 donated by Megan Carter, who died last year, will more than cover the cost of the East of England Ambulance Service (EEAST) replacing batteries in defibrillators, machines which give a big boost to the chances of survival for patients who collapse with cardiac arrests in the community.
The move will extend the life of 1,000 defibrillators, whose original batteries were due to expire this year, by a further five years at a cost of £125,000.
Community defibrillators, stored at sites across the region, play a crucial role in getting patients' hearts started again when seconds are vital after a victim suffers an arrest. They can be operated by untrained people as full instructions are given during use.
The defibrillators are called into action around 30 times a month across the region, equivalent to a virtually daily demand.
Gary Morgan, deputy director of service delivery with EEAST, said: "We are very grateful to Miss Carter and delighted that we have been able to put her generous legacy to such good use by extending the life of this vital equipment.
"Around 30,000 people in the UK go into cardiac arrest outside of hospital every year. Their chances of surviving drop 10 percent a minute if treatment is delayed, with survival rates currently stand at around one in 10."
Mr Morgan said: "Every second really does count, which is why it is so important to make sure as many people as possible have good access to a defibrillator within their community. It could make all the difference."
In one recent case a chef used one of the defibrillators to help save the life of a customer who had collapsed in his restaurant.
Anyone who calls 999 and needs access to a defibrillator will be told where the nearest equipment is and given a code to open the cabinet it is housed in. They will also be given full instructions on how to use it by the call handler.
Any organisation which has a defibrillator it would like to make available to the public can register it by visiting: www.eastamb.nhs.uk/your-service/campaigns/their-life-your-hands.htm You can also find out where your nearest community defibrillator is at the same link.