The ‘butterf ly’ in the neck that cuts your risk of stroke
ATINY titanium ‘butterfly’ implanted in the neck could give hope to half a million British patients blighted by drugresistant high blood pressure, dramatically reducing their risk of stroke, heart attacks and dementia.
In American trials, the bakedbean-size device – a featherlight, four-sided wire cage – has been able to improve patients’ prospects where medication had failed to do so.
Some, who still suffered high blood pressure despite being on the highest doses of medication, saw their readings drop to normal levels within months.
Although patients are still required to take tablets, their dose may be significantly reduced. Given European approval last year, the device, called MobiusHD, is now set to be offered to a select group of patients as part of a trial led by British experts.
The wire implant sits in a branch of one of the carotid arteries – the major blood vessels that run up either side of the neck, supplying the head. It applies gentle tension to bundles of nerves that are involved in regulating blood pressure.
These nerves, called baroreceptors, detect changes in blood pressure and send signals to the brain so it can make the necessary changes to keep blood pressure at safe levels.
Normally, when the walls of the carotid arteries are stretched by untreated high blood pressure, or hypertension, the baroreceptors signal to the brain to bring the blood pressure back to its normal level. The heart rate changes, causing blood vessels to dilate or constrict, and affecting how much fluid the kidneys excrete.
However, it’s thought that in drug-resistant patients, long-term raised blood pressure causes the baroreceptors to malfunction and set the body’s resting blood pressure at a dangerously high level. The reason some people’s pressure-regulating system stops functioning properly is not clear, but it is thought to be due to genetic or lifestyle factors.
The MobiusHD was designed so that it exerts pressure on these nerves, tricking the brain into thinking blood pressure is consistently raised.
It then signals to the body to lower the heart rate and widen the blood vessels, helping ‘reset’ the system.
Dutch cardiologist Dr Jan van der Heyden, who has been using the device on patients, said: ‘We’ve been following patients for more than two years and have seen dramatic improvements.
‘Some have been on the highest doses of four of five medications and basically housebound, because even going for a walk will raise their blood pressure to dangerous levels.
‘After having the Mobius implant, they have been able to reduce this to just one medication. They can go out, start exercising again, and live a normal life. They say it’s like being reborn.’
More than 150,000 Britons a year die as a result of uncontrolled or untreated high blood pressure, or hypertension, with stroke and heart attacks being the main causes of death.
High blood pressure also increases the risk of vascular dementia in later life, which is linked to small haemorrhages in the brain.
THE majority of the ten million people with hypertension are able to keep it in check by making lifestyle changes such as reducing salt intake, and taking a cocktail of pills. But for some patients, for reasons not yet fully understood, drug therapy fails.
This resistant hypertension is not only frustrating for patients, but it can also have disastrous consequences, as their stroke risk remains high.
MobiusHD is implanted during a minimally invasive procedure that takes about 50 minutes, under local anaesthetic.
A small incision is made in an artery in the groin, through which a fine, flexible tube – a catheter – is inserted.
The catheter, carrying the MobiusHD, is threaded through the circulation system and into the carotid artery, and left at the point where the vessel branches, in an area known as the carotid sinus, where the baroreceptors are situated.
The implant remains in place permanently and the patient is unable to feel it.
Studies suggest that there is an initial effect within 24 hours, and that blood pressure continues to fall over three months and then remain stable.
The procedure is set to go on trial at University College London Hospitals in a study expected to gain approval and begin recruiting later this year.
Professor Bryan Williams, director of research at UCLH and a specialist in hypertension, who will lead the study, said: ‘We are planning to carry out a research project with this device as we are interested in seeing the response from patients whose blood pressure medication is not adequate.’