Europeans suffering from stubbornly high blood pressure, despite swallowing multiple pills, now have a new treatment option in the form of devices that deaden nerves in the kidneys - and doctors are impressed.

The United States has yet to approve the technology, known as renal denervation, but several products are already available in Europe and researchers on Monday reported encouraging results from a series of studies testing them out in practice.

Teams from Germany, France and the Czech Republic told the European Society of Cardiology annual meeting that the new procedure offered benefits to a range of patients and seemed to effectively rejuvenate ageing blood vessels.

"This suggests that renal denervation might be a fountain of youth for blood vessels in patients with therapy-resistant hypertension," said Klaas Franzen from the University Hospital of Schleswig-Holstein.

Millions of people have hypertension that is resistant to drug therapy, putting them at risk of heart attacks and stroke.

That has encouraged several medical technology companies to invest in device-based high blood pressure treatments, which industry analysts believe will develop into a multibillion-dollar market.

Brokerage Jefferies has forecast annual sales could reach $2.8 billion by 2020.

Device makers that have already received approval to sell hypertension devices in Europe include Medtronic, the frontrunner, as well as Covidien, St Jude Medical, ReCor Medical and Vessix Vascular.

The new devices work by creating tiny scars along nerves in the kidneys - organs which play a pivotal role in regulating blood pressure by sending signals to the brain that can cause blood vessels to constrict.

The scarring process is carried out by threading a catheter through the renal arteries from the groin. It deadens the nerves and decreases systolic blood pressure, which is the top number in a reading. So far, there do not seem to be any worrying long-term side effects.

Cardiologists meeting in Munich said the technique had the potential to change blood pressure management and could in future be offered to a wider range of patients, not just those with the most obstinate hypertension.

"It is potentially a revolution," said Dr Gordon Tomaselli, a cardiologist at Johns Hopkins and president of the American Heart Association.

"Right now it is for resistant hypertension. But my guess is that in five years, if the studies continue to show benefits, it is going to move into less resistant hypertension ... all forms of hypertension theoretically could be treated this way."

Artery stiffness reduced

Franzen's study in Schleswig-Holstein, Germany, looked at renal denervation in 21 patients and found it not only cut blood pressure but also reduced arterial stiffness. In fact, Franzen's team concluded the improvement in stiffness was equivalent to a 10-year reduction in ageing.

Stiffness is the artery walls is associated with an increased risk of heart attacks and strokes.

A 26-patient Czech study, meanwhile, found the new technique improved the ability of the left side of the heart to contract by more than 10 percent in patients with heart failure.

A second German study involving 173 patients found renal denervation reduced rates of depression and improved sleeping patterns, while a French trial with 35 patients found the technique worked well in day-to-day practice.

As the process involves an invasive procedure, there can be complications, such as haematomas, or the collection of clotting blood under the skin.

But Dr. David Holmes of the U.S. Mayo Clinic College of Medicine said the overall risks seemed low, reflecting the fact that the renal artery was quite large and the procedure did not involve any permanent implant.

Also at the Munich meeting, Medtronic announced updated results from a clinical trial involving its own Symplicity system, showing that it continued to provide sustained blood pressure reduction for up to 18 months.