Tech to check blood flow
New implant that can warn if you’re about to have a heart attack
AHIGH-TECH implant that monitors blood flow 24 hours a day could protect patients against heart attacks.
The tiny metal tube is a type of stent, very similar to those implanted in thousands of people every year to open up clogged arteries.
But unlike conventional stents, it has a miniature sensor – not much bigger than a speck of dust – that can detect changes in the rate of blood flow that might indicate a blockage and a potential heart attack.
Studies suggest it can detect a blockage early and then send a warning message to a doctor’s phone or computer – the doctor would then contact the patient to arrange treatment.
The Canadian researchers are planning further studies and will test it in humans within the next couple of years.
Heart attacks occur when the supply of blood to the heart is suddenly blocked, usually by a clot, and as a result some of the heart’s muscle is permanently destroyed.
The treatment after a heart attack is an angioplasty, where a balloon is inserted into the artery and inflated to clear the blockage, and then a stent – a short wire-mesh tube – is used to keep the blood vessel open and allow blood to flow normally.
More than 70 000 people a year in England alone have a stent fitted.
However, a major problem with conventional stents is restenosis, where surrounding tissue becomes inflamed in response to the foreign body, causing another blockage and raising the risk of another heart attack.
About a third of patients fitted with so-called bare metal stents suffer restenosis. Rates are lower with a new generation of drug-eluting stents (devices coated in medicine that is slowly released around the site of the blockage), but a significant proportion still develops restenosis.
Currently, the first sign that it has developed is severe chest pain, or even a heart attack.
Scientists at the University of British Columbia in Canada believe the new stent could be a solution.
They took an ordinary stent and used laser beams to “weld” on a sensor that’s designed to monitor blood pressure in the immediate area, as well as the rate of blood flow.
Next to the sensor scientists positioned a tiny antenna, which picks up the readings from the sensor and wirelessly transmits them to a phone or computer hourly.
This would give doctors time to contact the patient to arrange an angioplasty before a heart attack occurs.
So far, the implant has only been tested on animals, but the results of recent experiments, published in the journal Advanced Science, showed the device was able to detect the beginnings of a blockage by constantly measuring blood flow to see if it was being impeded in any way.
It also transmitted blood pressure readings in arteries around the heart: a rise could signal that restenosis is setting in and the artery is in danger of becoming blocked.
Researchers hope to begin testing the implant in humans within the next couple of years.
Dr Cara Hendry, a cardiologist at Manchester Heart Centre, said the smart stent could help some patients with severe blockages, but warned it could lead to others getting treatment that might do more harm than good.
“Patients with restenosis don’t always develop symptoms and it doesn’t always result in a clot,” she says.
● A tiny sponge-like device attached to the heart could help people after a heart attack.
The device, developed by scientists from Massachusetts Institute of Technology in the US and Galway University in Ireland, is attached to a thin tube which has a tiny “port” on the tummy. Doctors can then inject drugs into the port which travel up the tube and are stored in the sponge, which gradually releases them over several weeks to help heal damaged heart muscle.
The sponge can also store stem cells that can generate new cardiac muscle.
It solves one of the major problems with getting drugs and stem cells to the heart – stopping them floating off round the body.
Further studies are planned. – Daily Mail