Renal denervation
What is renal denervation?
Renal sympathetic denervation is a new treatment for
hypertension (high blood
pressure). Hypertension raises the risk of having a
heart attack, stroke or death. It is usually treated with
lifestyle changes or medication. Nerves located in the renal
artery wall communicate information from the kidney to the brain to
control blood pressure. In this procedure, a device is
inserted through the groin to deliver heat energy to the renal
nerves with the aim of reducing blood pressure.
Who is renal denervation suitable for?
This is a new procedure for blood pressure so there is only
limited experience of the technique. So far it has been shown
to be effective in reducing blood pressure for those people who
have "resistant" hypertension. This is usually a BP >
160mmHg despite being treated with at least three drugs for
blood pressure.
What does the procedure involve?
The procedure is usually carried out under local
anaesthetic. A tube is inserted into the artery in the groin
(femoral artery) and a catheter is placed under X-ray guidance into
each of the renal (kidney) arteries in turn. Heat energy is
then delivered to the renal artery in two minute
bursts. Around five or six bursts of energy are
given to each artery. This can be painful but this is
controlled by giving painkillers into the vein during the
procedure. The whole procedure lasts around an hour. You
will usually stay in hospital for at least 6 hours after the
procedure and sometimes may need to stay overnight.
What are the benefits?
A randomised controlled trial of 100 patients treated by renal
artery denervation showed an average blood pressure reduction of
32/12 mmHg in the renal denervation group after six
months1. A case series of 153 patients reported an
average blood pressure reduction of 25/11 mmHg at six months,
26/14 mmHg at 12 months and 32/14 mmHg at 24
months2. Not everyone had this level of blood
pressure reduction. Around 1 in 10 people did not have much
benefit from the treatment. There is no long term data
(beyond two years). Most people carried on with all their
medication after the procedure.
Are there any risks?
The most serious risk is dissection of the renal
artery. This happened in one patient out of 153 and can
be treated with a stent at the time2. Other adverse
events include the risk of bruising or bleeding in the groin,
nausea and back pain. These usually subside but may take up to
a month. There have not been any reports of damage to kidney
function but this is a theoretical risk. NICE are in the
process of producing their evaluation of this procedure.
References
- Renal sympathetic denervation in patients with
treatment-resistant hypertension (The Symplicity HTN-2 Trial): a
randomised controlled trial. Symplicity HTN-2 Investigators, Esler MD, Krum H, Sobotka PA, Schlaich MP, Schmieder RE, Böhm M. Lancet. 2010 Dec 4;376(9756):1903-9.
- Catheter-based renal sympathetic denervation for resistant
hypertension: durability of blood pressure reduction out to 24
months. Symplicity HTN-1 Investigators. Hypertension. 2011
May;57(5):911-7.
