Wire ‘cage’ to lower high blood pressure

AN iMplANT that resembles the wire over a champagne cork could offer a new way to tackle high blood pressure.

The tiny cage- like device is implanted in an artery in the neck where specialised nerves are located that are key to the body’s natural blood pressure control mechanism.

The nerves, called baroreceptors, act as sensors that detect when artery walls are under pressure — a sign that blood pressure is rising too high — and then relay this information to the brain. As a result, the heart rate drops, causing blood vessels to dilate or widen which lowers blood pressure.

But research suggests that long-term raised blood pressure can cause the baroreceptors to malfunction so the nerves stop responding to tension building in the artery walls — and start to interpret high blood pressure as ‘normal’.

The new device, developed by U.S.-based Vascular Dynamics, puts pressure on the sensors that resets them, so the brain believes that blood pressure is permanently raised and takes steps to bring it back down. More than 200 people are taking part in a clinical trial of the device following research showing it significantly lowered dangerously high blood pressure in a small group of patients.

There are an estimated 12 million people in the UK with high blood pressure, and, left uncontrolled, it can increase the risk of stroke, heart attacks and vascular dementia.

Around 500,000 people in the UK have so-called resistant hypertension, meaning their blood pressure remains high despite taking three or more different types of medication for it.

The four-sided titanium implant, which is roughly the size of a fingernail, may be especially beneficial for this group of patients.

it is inserted folded up through a tiny incision made in an artery in the groin. loaded inside a tube or catheter, it is navigated via the blood vessels and up into one of the two carotid arteries in the neck into an area called the carotid sinus, a collection of nerve endings where the baroreceptors are situated.

The procedure is carried out under local anaesthetic.

Once in place in the neck, the cage is opened and positioned so that it puts a tiny amount of force on the baroreceptors.

A study reported in The lancet two years ago involving 30 patients in The Netherlands and Germany who’d had the device put in, showed that in the majority of patients, blood pressure reduced towards a normal level within a few months.

A trial is now under way with about 200 patients whose high blood pressure has not been controlled by medication.

The study involves centres around the UK including the Queen elizabeth University hospital Glasgow, Royal Sussex County hospital, and St Bartholomew’s hospital in london.

Dr punit Ramrakha, a consultant cardiologist at the hammersmith hospital in london, says targeting the baroreceptors can have ‘a great impact’ on blood pressure.

he adds: ‘The initial clinical trial was encouraging and it would be exciting to see if this new trial will allow the device to be licensed for more widespread use.’