Zapping Nerves to Lower Blood Pressure

Hypertension that is treatment-resistant may be reduced by stopping nerves connected to kidney

(RxWiki News) High blood pressure can trigger heart disease, stroke and kidney failure. Medication can help, but it doesn’t work for everyone. A nerve procedure may offer a new type of treatment for those patients who don't respond to high blood pressure medicine.

The kidneys influence blood pressure by controlling the excretion of salt and water from the body, and by communicating with the brain to help regulate pressure.

A relatively new technique that removes nerves connecting the kidney to the brain may be effective in lowering hypertension (high blood pressure).

"Check your blood pressure regularly."

Julian Paton, PhD, a professorial research fellow at the University of Bristol’s School of Physiology and Pharmacology in England, and colleagues found that, in mice, removing nerves connecting the kidney to the brain reduced blood pressure.

In the present study, researchers from the University of Bristol collaborated cardiologists from the Bristol Heart Institute to test the procedure on 19 humans who had high blood pressure. Angus Nightingale, MD, and Andreas Baumbach, MD, adopted the technique from Paton and his associates.

The technique, called renal denervation, involves inserting a tiny tube into an artery in a patient’s leg. The tube is then positioned in the artery, feeding blood to the patient's kidneys.

Nerves to the kidney, which surround this artery, are destroyed by radio-frequency energy that is emitted from the tube.

Four patients showed a 10 percent decrease in systolic blood pressure at six months, according to the study. Baroreflex sensitivity improved in all patients. Baroreflex is the body’s mechanism for natural blood pressure regulation.

It is a network of natural blood pressure sensors (baroreceptors) located throughout the arteries and veins that helps regulate blood pressure in concert with the central nervous system.

The authors concluded that “...renal denervation improves blood pressure in some patients” and “...baroreflex sensitivity is consistently improved.”

In a 2010 study published in The Lancet, scientists tracked about 50 patients who received renal denervation and, after six months, these patients showed an average 32 point decrease in systolic and a 12 point decrease in diastolic pressure.

"The technique is very straight forward, performed as a day case and there are no side effects,” said Dr. Baumbach in a press release. “It is becoming a popular technique for patients with both resistance and poor tolerability to high blood pressure medication.”

The authors are still uncertain as to why the technique works, writing “...mechanisms underlying the blood pressure (BP) reduction remain unclear.”

Professor Paton added in a statement, “The problem with high blood pressure is that patients develop resistance to their tablets or unpleasant side effects. Our new interventional approaches are based on studies where we have found causative mechanisms generating high blood pressure so we think that they will be most efficacious in patients.

And, with luck, they will also mean less pill taking too.”

One in three American adults has high blood pressure, or hypertension, according to the Centers for Disease Control and Prevention (CDC). More than half of people with high blood pressure do not have their condition under control.

That’s why it’s important to have your blood pressure checked regularly, according to the CDC.

The study was published in July in Hypertension. The researchers are receiving funding from Medtronic to further improve the technique and expand patient trials.

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Review Date: 
July 5, 2013