Kidney Nerve Deactivation Could Ease Hypertension
MONDAY March 30, 2009 -- Using a catheter-based technique to deactivate nerves in the kidneys -- a process called renal denervation -- could help people with tough-to-treat high blood pressure, a new study suggests.
About 30 percent to 40 percent of the world's population has hypertension and about 5 percent to 10 percent of those have resistant hypertension. There's a link between hyperactivity of the sympathetic nervous system (serving the kidneys) and the progression of high blood pressure, as well as chronic kidney disease and heart failure, according to background information in a news release on the study.
The research included 45 patients with resistant hypertension, defined as having a systolic blood pressure of 160 mmHg, while taking three or more antihypertensive medications, including a diuretic. Some of the patients underwent what's known as "percutaneous radiofrequency catheter-based treatment" and were then followed for up to one year.
The treatment involves placing a catheter in the femoral artery (in the abdomen/thigh), guiding it to the renal (kidney) artery, and advancing it to where the kidney nerves are located. Radiofrequency energy is then used to disrupt the nerves.
Before treatment, the patients' mean blood pressure was 177/101 mm Hg. After treatment, mean blood pressure was reduced by -14/10, -21/-10, -22/-11, -24/-11, and -27/-17 mm Hg at one, three, six, nine and 12 months. Among the non-treated patients, the mean rise in blood pressure was +3/-2, +2/+3, +14/+9, and +26/+17 mm Hg at one, three, six and nine months.
"We showed an excellent safety profile of this brief, catheter-based therapy," wrote Henry Krum, of the Centre of Cardiovascular Research and Education in Therapeutics, Monash University, Melbourne, Australia, and colleagues. "No long-term adverse events resulted from the procedure ... Therapeutic renal denervation led to a large and persistent decrease in blood pressure, which was achieved in patients resistant to multiple existing hypertensive drug types. Moreover, reduction of blood pressure was evident as early as one month, was further reduced at three months, and persisted through subsequent assessments."
The findings were presented at the American College of Cardiology meeting in Orlando, Fla., and appear online and in an upcoming print issue of The Lancet.
If further studies prove the value of this treatment, it must be reserved for patients with truly resistant hypertension, only after drug therapy has failed or isn't tolerated by the patient, experts wrote in an accompanying comment.
"We strongly believe that Krum and colleagues provide hope for the management of a difficult clinical condition," wrote Dr. Michael Doumas, of George Washington University in Washington, D.C., and Dr. Stella Douma, of Hippokration Hospital, Aristotle University of Thessaloniki, Greece. The two experts co-authored an accompanying commentary in the journal.
The American Heart Association outlines treatment guidelines for resistant hypertension.
Posted: March 2009