How does a butterfly implant the size of a bean help weak hearts?

A butterfly-shaped implant placed in the neck offers a radically new approach to heart failure, a condition that affects one million Britons.

The metal device, the size of a baked bean, is inserted into one of two carotid arteries that run along either side of the neck and connect the heart to the brain.

The “wings” of the butterfly-shaped device exert a gentle pressure on the receptors on the mucous membrane of the carotid artery. So-called baroreceptors are extremely sensitive nerve endings that regulate blood pressure and heart rate.

Research shows that gently applying steady pressure to these receptors sends a signal to the brain to lower the heart rate, reducing the workload on the heart and therefore heart failure (which means heart failure). should).

Slowing the heart rate also gives the left ventricle (main pumping chamber) more time to fill with oxygenated blood.

When the heart contracts, more blood is pumped throughout the body. Improving the oxygen supply to major organs and muscles means reducing symptoms of heart failure such as shortness of breath, severe fatigue, and swelling in the legs and feet (caused by blood pooling in the lower body).

Heart failure often develops after a heart attack; other risk factors are hypertension, smoking and obesity.

Heart muscle damaged by a heart attack stops working efficiently, and the weakened heart responds by working harder to maintain blood flow.

This puts pressure on him and he gradually gets weaker. Treatments include medications such as blood pressure pills and lifestyle changes to reduce pressure on the heart. But many patients eventually need a pacemaker to keep their heart rate steady and at the correct rate.

Others undergo cardiac resynchronization therapy, in which an implant in the heart causes the left ventricular walls to contract all at once, rather than timing out with each other, as can happen in some cases of heart failure. But these treatments require invasive surgery, which carries the risk of infection.

New solutions are needed because heart failure is becoming a bigger problem as more people survive heart attacks and the aging population increases. The butterfly implant, called MobiusHD, can be placed in just 30 minutes. The idea is based on a form of treatment known as baroreceptor activation therapy.

Numerous studies show that applying gentle pressure to receptors in the neck makes them think the blood is pressing on them because the blood pressure is too high, slows the heart rate and reduces the pressure on the heart.

To control blood pressure and lower heart rate, the brain responds to a signal from receptors in the brain by dilating blood vessels (to allow blood to flow more freely) and slowing the rate at which the heart contracts.

Heart failure often develops after a heart attack; other risk factors are hypertension, smoking and obesity.

A similar implant (called Barostim NEO) also activates nerves in the neck and is approved for use in the treatment of heart failure in Europe.

But because this implant relies on electricity to stimulate baroreceptors, it requires a matchbox-sized generator to be implanted in the chest with wires connecting it to the carotid artery in the neck. The butterfly plant does not require a feeder and is therefore much easier to place.

Under general anesthesia, a small incision is made in the carotid artery just below the chin. A plastic tube with a collapsed implant is threaded through a wire into the artery where the baroreceptors are located. When it snaps into place, it opens and immediately applies gentle pressure to the receptors along the artery.

A clinical trial is ongoing at nine hospitals in Australia, Canada, the United States and Germany involving 40 heart failure patients who have not improved on current treatments to see if this device helps. The trial is expected to end in December 2023.

Initial data from 19 patients presented at a cardiology conference in Frankfurt in June showed all improvements in heart rate and blood flow from the heart.

Professor Klaus Witte, cardiologist at Leeds Institute of Cardiovascular and Metabolic Medicine, says the implant could potentially help patients with heart failure, but added: “Preliminary data looks promising, but we need a larger randomized trial to really test its effects. sure.