Kidney zap lowers blood pressure

By Michelle Roberts
Health reporter, BBC News

  • Published

A short blast of radio waves to the kidneys can help control high blood pressure in patients who do not respond to medication, a study shows.

The pioneering work, described in The Lancet medical journal, selectively severs nerves to the kidney that play a key role in regulating blood pressure.

Although still in the testing phase, experts say the procedure could one day help hundreds of thousands of patients.

Half of patients fail to achieve good blood pressure control with drugs.

This is partly because it can be difficult to remember to take medication every day. But for up to a fifth of patients it is because the drugs simply have no effect.

High blood pressure is an exceedingly common condition, affecting around one in three adults in England.

Experts believe the new procedure could help many of these better control their condition, thereby lowering their risk of future strokes and heart attacks.

Promising results

Doctors led by Professor Murray Esler at the Baker IDI Heart and Diabetes Institute in Melbourne, Australia, have been testing the safety and effectiveness of the therapy.

To get to the kidneys, the doctors use a long, thin piece of tubing called a catheter that is threaded into an artery in the groin and guided up to the kidney.

Once in place, the catheter is connected to a machine that generates radio waves, known as radiofrequency energy.

In this way, a short burst from the machine can knock out a number of tiny nerves that run in the lining of the arteries of the kidney.

By stopping these nerves from sending signals the treatment lowers blood pressure.

The Australian team, working with 24 centres across the globe, have tested the treatment in trials involving more than 100 patients.

They found the therapy lowered blood pressure by about 10mmHg or more - which although is not enough to return blood pressure to a 'normal' level is enough to reduce some of the associated health risks of very high blood pressure.

And, importantly, there were few side effects if any.

Six months after the treatment, 41 (84%) of 49 patients who underwent the procedure had a reduction in systolic blood pressure of 10mmHg or more, compared with 18 (35%) of 51 controls.

The first patient in the UK received the innovative procedure at Barts and The London NHS Trust a year ago.

Commenting on the findings, Professor Jeremy Pearson of the British Heart Foundation said: "This trial opens up a potentially exciting new avenue for the treatment of patients with high blood pressure who do not respond well to current medicines.

"Further studies are needed to see if this invasive procedure will be acceptable to patients and produce long-lasting effects that are safe and reduce future cardiovascular events."

Professor Graham MacGregor, chairman of UK charity the Blood Pressure Association, said: "This is exciting research which could play a part in tackling the massive issue of high blood pressure, which affects 16 million UK adults and is a major killer through the strokes and heart attacks it causes."

But he said most people would not need to undergo such invasive treatment as, for the majority, high blood pressure can be successfully controlled through prescribed medicines and a healthier lifestyle.

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