TUESDAY, March 29 (HealthDay News) -- A technique that
interrupts nerve signals between the kidneys and brain dropped
blood pressure to normal levels in 39 percent of patients with
drug-resistant hypertension, according to a small new study led by
At 24 international sites, 106 patients with uncontrolled high
blood pressure (hypertension) randomly received either oral
medication or renal denervation treatment, a procedure that uses a
catheter-based probe emitting high-frequency energy near the renal
artery to deactivate nearby nerves. It was the first human
randomized trial of its type, with U.S. experts hailing the results
as exciting and "visionary."
Six months later, the patients who received the nerve block
procedure had experienced an average systolic blood pressure drop
of 32 mm Hg and a diastolic blood pressure drop of 12 mm Hg, the
study authors said.
Half of the nerve block patients showed a measurable benefit,
and 39 percent reached recommended blood pressure levels, said
study author Dr. Marc Sapoval, professor of clinical radiology and
chair of the cardiovascular radiology department at Hopital
Europeen Georges-Pompidou in Paris.
The procedure also appeared safe, with a low incidence of local
complications, researchers reported.
Prior to the study, all the participants had had resistant
essential hypertension, which means that a doctor could not figure
out what was causing their high blood pressure (a systolic blood
pressure of 160 mm Hg or more, or 150 mm Hg in people with type 2
diabetes) and that three or more drugs had failed to control the
While encouraged by the results, Sapoval noted that the research
was funded by manufacturers of the catheters and generators used in
the study, and that the study was small, cautioning that more and
larger independent trials and patient follow-up should be done.
According to background materials accompanying the study, the U.S.
Food and Drug Administration is planning a trial of the procedure
involving more than 100 U.S.-based interventional radiology
Sapoval also stressed that the research is still experimental
and that the procedure should only be done by interventional
radiologists on carefully screened patients in controlled research
and academic settings.
The research was scheduled to be presented Monday at the Society
of Interventional Radiology's 36th annual scientific meeting in
"If the results are confirmed, it will be a frequent procedure," Sapoval said. "If further trials show that patients with less severe hypertension can benefit also, the number of patients will be huge."
Why renal denervation works is not entirely clear, Sapoval said,
but it appears to dampen overactivity of the sympathetic nervous
system, which can trigger high blood pressure.
About 25 percent of American adults have high blood pressure,
most of which has no known cause, said Dr. Kirk Garratt, clinical
director of interventional cardiovascular research at Lenox Hill
Hospital in New York City.
"If this technique works, I believe it will be used first in patients with very, very difficult blood pressure issues," Garratt said. "Blood pressure trouble is extraordinarily common, and the cumulative cost measured by the cost of medications alone is very substantial. But . . . poor control drives up the cost of health care overall."
Described as minimally invasive, renal denervation may be an
outpatient procedure if it becomes commonplace, which could happen
in several years, Garratt said.
"It's a very novel and advanced technique, but the technical aspect would be familiar and easily adopted," he said.
Dr. Barry Cohen, medical director of the catheter laboratory at
Gagnon Cardiovascular Institute at Morristown Memorial Hospital in
New Jersey, called the study participants' blood pressure reduction
"really unbelievable," and hopes the treatment could decrease the
risk of cardiovascular and kidney problems arising from high blood
When promising research such as this is reported, "we think it's
a shoe that's going to fit every foot, but we know we always have
to be cautious and there may be some pitfalls. I think this is
extremely visionary and . . . groundbreaking," Cohen said.
Because the study is to be presented at a medical meeting, it
should be considered preliminary until it is published in a
peer-reviewed medical journal.
The U.S. National Heart, Lung and Blood Institute has more
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