The arteriovenous ROX Coupler and deployment catheter

High blood pressure increases the risk of stroke, heart attack, heart failure, kidney damage and eye problems. A new device being trialled could be an alternative to high blood pressure medication. An ongoing study on the device the size of a paper clip inserted in the groin is showing promise to significantly improve blood pressure levels in patients with resistant hypertension (where three or more drugs have failed to achieve blood pressure control).

Experts say the device could be a new way of controlling blood pressure, particularly in hard-to-treat cases. High blood pressure affects one in three adults in the UK, with around 5% of this group suffering from resistant hypertension, which does not respond to medication.
The device, called a coupler, made by ROX Medical in California which also funded the study, creates a chamber between the artery and vein in the upper thigh. The treatment involves a minimally invasive, catheter-based procedure to place a small coupler between the artery and vein in the upper thigh. The procedure reduces peripheral vascular resistance by diverting some of the higher-pressure arterial blood to the low pressure and highly compliant venous system; essentially restoring some of the lost compliance back into the vascular system.

Researchers at Queen Mary University of London, which led the study, tested the device on 42 patients with high blood pressure which had not responded to at least three types of drug treatment. They compared the effects with 35 patients who were given the standard medical treatment for uncontrolled high blood pressure. Patients were drawn from 16 centres across Europe. The study found “significant reductions in blood pressure” in the coupler group six months after the device was implanted. For patients in this group, there were fewer hypertensive complications and fewer hospital admissions for high blood pressure emergencies. Patients who had the coupler inserted were also able to reduce their medication.

“Unlike renal denervation, which involves irreversibly destroying the nerves supplying the kidneys, this procedure only involves vascular structures remote from vital organs. It is also fully reversible which is an attraction for patients. However, the device did have side-effects. In around 29% of patients, swelling developed in the leg in which the coupler was inserted. This required another short procedure to insert a stent in the vein.
Lead author Dr Melvin Lobo, from Queen Mary University of London, and director of Barts blood pressure clinic, said this was an easy thing to do and was probably due to turbulence caused by the device in the thigh. But he acknowledged there was more to learn about the device. “We need more research to explore the long-term effects of the coupler, better understand its safety and understand more about how it works within the body.

“We must find better means of treating high blood pressure as drugs do not work for everyone and the coupler is a big step forward in our search for alternative treatment.”Prof Tom MacDonald, president of the British Hypertension Society, and professor of clinical pharmacology at the University of Dundee, said the device could be “a fantastic thing for patients”. “This procedure may be especially beneficial for those patients whose hypertension has not been controlled through traditional medications and who live in constant fear of a heart attack or stroke.
He added: “In the long run, though, it could benefit an even wider range of patients with hypertension, and it may even lead to greater understanding of how hypertension arises and is perpetuated. One might even speculate that such treatment may even herald a new era of device-based therapy of hypertension in which patients may ultimately be freed from the need to take anti-hypertensive drugs on a daily basis lifelong.”

The study forms part of the Barts and The London’s NIHR Cardiovascular Biomedical Research Unit’s clinical trials programme in device-based therapy of hypertension to better understand the causes of hypertension and ultimately to bring novel treatments into the clinic.