Nov. 17, 2010 (Chicago) -- An experimental device that destroys nerves near the kidney helped to lower blood pressure in people whose hypertension remained out of control despite treatment with an average of five drugs, Australian researchers report.
In a six-month study of about 100 people, systolic blood pressure (the top number) dropped an average of 32 points in people treated with the device on top of the best available medication. Diastolic blood pressure (the bottom number) fell 12 points.
In contrast, blood pressure readings remained at the same stubbornly high levels among people on medication alone, says Murray Esler, MD, of Baker IDI Heart and Diabetes Institute in Melbourne.
The findings were presented here at the American Heart Association’s Scientific Sessions 2010 and simultaneously published online in the Lancet.
The device uses radio waves to silence nerves leading into and out of the kidney. These so-called sympathetic nerves contribute to the development and perpetuation of high blood pressure, Esler says.
"This could revolutionize the way we treat medication-resistant hypertension," says Suzanne Oparil, MD, of the University of Alabama at Birmingham.
Drug-resistant hypertension -- blood pressure that remains above goal in spite of concurrent use of three or more drugs of different classes -- is on the rise, now affecting about 15% of Americans, Oparil tells WebMD. She was not involved with the study.
"Many patients are uncontrolled on four or five drugs and have truly refractory hypertension," she says. "If it cannot be controlled medically, it carries a high cardiovascular risk."
High blood pressure is the No. 1 risk factor for premature death worldwide. In the United States, about 75 million Americans have hypertension and only about two-thirds are treated.
How It Works
The new procedure involves inserting a catheter-based probe through a puncture in the groin and maneuvering it through blood vessels until it reaches the arteries near the kidney.
Once there, the device emits short bursts of low-power radiofrequency energy to deactivate nerves lining the artery. Each person gets four to six two-minute treatments.
A total of 49 people treated with the device plus medication and 51 treated with medication alone completed the new study.