Undearm implant that jump-starts an irregular heart
01:05 GMT, 15 May 2012
Tragedy: Runner Claire Squires died during last month's London Marathon
A million Britons suffer from an irregular heartbeat, or arrhythmia, and every year 70,000 die as a result.
All ages are affected, as was shockingly demonstrated by the collapse of Bolton Wanderers footballer Fabrice Muamba in March, and the death of charity runner Claire Squires at the London Marathon last month.
The 30-year-old hairdresser from Leicestershire had reportedly been diagnosed with an irregular heartbeat but refused to let it stop her running.
Now a new implant is set to transform the lives of patients with arrhythmia, even allowing them to take part in ‘stressful’ events, such as marathons.
In a healthy heart, electrical signals cause it to contract and pump blood at a regular speed.
If there is a problem with these signals, the heart beats too slowly, too quickly or irregularly, which is known as an arrythmia.
They are mostly harmless but can sometimes lead to a fatal sudden cardiac arrest, often during strenuous activities because the heart has to work harder, which can cause the electrical signals to go out of rhythym.
Arrhythmia frequently affects people who have a history of congenital heart disease.
However, the number of people with these ‘heart flutters’ is on the rise, especially among younger people, possibly caused by an increase in factors such as excessive drinking or stress.
The Subcutaneous Implantable Cardioverter Defibrillator (S-ICD) is positioned under the armpit.
It detects when the heart is beating irregularly, and has a built-in defibrillator to zap the patient back to life by giving them a controlled electric shock.
Implanted defibrillators such as this have been used since the Eighties.
But there are key differences between the conventional devices and the new one.
A million Britons suffer from an irregular heartbeat, or arrhythmia, and every year 70,000 die as a result
The conventional version is implanted under the collarbone and monitors the heartbeat via wires that are passed through a vein directly into the heart.
These wires pose a risk of serious infection and, because the heart muscle moves constantly, there is also a chance that the wires could fracture and need to be replaced.
Consequently, one in five leads will have problems in fewer than ten years — and the surgery to repair this carries a further risk of infection.
The new implant, by contrast, has just one 3mm diameter wire going across the chest under the skin outside the rib cage, meaning there is less risk of infection.
Another advantage with the new device is that patients are less at risk from a ‘false’ shock — around a third of the shocks given by ICDs are unnecessary, triggered by variations in heartbeat that pose no immediate danger to the patient.
However, these shocks can be extremely painful and cause anxiety — some patients have described them as feeling like a horse kick from inside the chest.
‘A patient will physically jerk with shock from either the standard ICD or the S-ICD,’ says Dr Adrian Morley-Davies, a cardiologist at University Hospital of North Staffordshire in Stoke. ‘It feels very painful.’
With the new device, the wire is positioned further away from the heart, so it is less likely to pick up the organ’s electrical ‘noise’, which can trigger a false alarm.
‘The new S-ICD device doesn’t appear to give the false shocks that the old one did,’ confirms Dr Andrew Grace, a cardiologist at Papworth Hospital, Cambridge, who helped to develop the new implant.
‘And it’s not touching the heart, so if an infection did happen, you can take it out without any problems.’
Furthermore, because the wire is not attached to the heart, but is positioned a short distance away, the impulse can spread across the heart, giving a shock that is two-and-a-half times more effective than the standard implant, which gives only a direct ‘hit’.
The battery is also designed to deliver higher energy.
Fitting and maintenance of the new device is also simpler — and cheaper.
Doctors say placing the implant is a more straightforward, one-hour procedure than with the traditional ICD, which is actually half the size but which can take up to three hours to fit (the new device is matchbox-sized).
Studies at Papworth and in New Zealand, published in the New England Journal of Medicine, found the new device — which has been available on the NHS for the past two years — was 100 per cent successful in treating severe arrhythmias.
Sean Rodgers, 43, was among the first in the country to have one fitted.
The housing repair manager and seasoned runner had a cardiac arrest in March 2009, and was effectively ‘dead’ for 15 minutes.
He was saved only because his wife Maria knew how to give chest compressions.
Even so, he remained in a coma for a week. Maria and their two teenage children were warned it was unlikely he would survive.
When Sean recovered, he was told he had Long QT Syndrome, a condition affecting 6,000 Britons, where the heart takes longer than normal to reset its electrics after each beat.
He had the device fitted in January 2010 at the Northern General Hospital, Sheffield.
Ten months later, he had another cardiac arrest. Luckily, this time, he’d had the S-ICD fitted.
‘The S-ICD saved my life,’ says Sean, of Mexborough, South Yorkshire.
‘I got up off the sofa and suddenly felt my eyes rolling into the back of my head before it went dark. But then the device must have kicked in.’
An implanted defibrillator is not the same as a pacemaker, which sends regular electrical pulses to help keep the heart beating regularly.
Instead, it’s like a portable defibrillator that will kick-start the heart back to life if it stops beating, explains William McKenna, professor of cardiology at London’s Heart Hospital and president of the Cardiomyopathy Association.
‘The S-ICD can’t pace the heart, so is unsuitable for those with advanced disease or older patients who also need pacing.’
However, it is suitable for most younger people who have arrhythmias.
‘They are particularly suitable for younger people who are at risk of sudden death but who are very active,’ he adds.
That is something that Sean Rodgers can now appreciate only too well.
‘The S-ICD has given me the confidence to get on with life,’ he says.
‘I even completed the London Marathon this year.
‘It has given me the security of knowing that, if needed, my heart will be given a jump-start.’
For more information, visit bhf.org.uk and arrhythmiaalliance.org.uk