A 37-year-old karate champion has become one of the first people in the country to have an upgraded version of the world’s smallest pacemaker implanted inside her heart.

Mairi Kerin, a PhD mechanical engineering student, said the new device – which is the size of a vitamin pill – has saved her martial arts career as it would be too dangerous to have a traditional pacemaker fitted near to her skin in case it got kicked during a match.

The sports scholar at the University of Birmingham was fitted with the device by consultant cardiologists Dr Paul Roberts and Dr Arthur Yue at University Hospital Southampton after she suffered from infrequent AV block – a condition where the heart forgets to beat and where the ventricle and atrium of the heart are out of sync.

The Micra AV Transcather Pacing System (TPS) is inserted through a vein in the groin and positioned inside the heart with small anchors.

Traditional pacemakers are implanted in a cavity or “pocket” in the chest, and are connected to the heart by leads.

The device fitted to Ms Kerin, made by medical technology company Medtronic, has been upgraded to enable it to ensure that all the chambers of the heart beat in synchrony.

Ms Kerin has practised karate for 19 years and has been a member of the senior Irish squad since 2013 – and has won hundreds of national and open championship titles, most recently at the British University Championships.

Ms Kerin said: “It was a huge shock to be diagnosed with a heart condition that I knew nothing about. When the doctors talked to me about a pacemaker my first thought was that my karate career would be over.

“It would be dangerous to have a device implanted just under my skin near my left shoulder as it could be easily be damaged or dislodged by a kick or punch to that area of my body during a match.

“To then learn that there was a pacemaker that could be implanted inside my heart was amazing and gives me hope that I can return to competitive karate soon.”

Dr Roberts said: “This is an amazing piece of technology with advanced sensors and algorithms that fit into something the size of a vitamin tablet.

“What is clever about this latest generation of the Micra pacemaker is that it uses an accelerometer that listens to what is happening in another part of the heart and matches it to the pacing of the ventricle so the chambers of the patient’s heart beat in synchrony.”

Dr Roberts added: “With AV block we need to make sure that the atrium and the ventricle work in sync.

“The Micra pacemaker uses an accelerometer – similar to the device that tracks movement in a FitBit or smart phone – to detect contraction of the atrium by filtering out other noises and movement in the heart to ensure that electrical signals are sent to the ventricle at exactly the right time to help the heart to beat as it should.”