Monday, May 21, 2012


Last week, I was asked  by two patient about renal denervation for the control of hypertension. When I was wondering why, my secretary ( she reads Chinese press ) told me that one of my colleagues in town, had written an article in the Chinese press describing renal denervation as a new way of treating hypertension. Well, in a way, that is correct. What is left out is that this technique is still experimental. It does have CE mark approval, not FDA approval. CE mark approval means that it is safe for use and trials. It does not mean that it has been proven effective.
There is much that we do not know about renal denervation.
First, what we know is that there is a network of nerves around the proximal ( the beginning portion of the artery to the kidneys ) portion of the renal artery. These nerves do have a role in the control of hypertension. We know that ( pioneering work done by the Australian and the Poles ) if you were to ablate ( deaden ) these nerves, blood pressure seem to lower. However, this lowering was rather inconsistent.
When the Australians and Poles began this work, they tried it on people whose blood pressure could not be controlled, despite 4-5 medications. They found that some of the patients BP came down, giving the basis of renal denervation as an invasive means to control hypertension.
Secondly, what we did not yet understand is that, the response does not seem to come immediately. It sometimes take weeks, if not months, to see the BP come down. Whats even worse, is that about 20-30% of patients treated did not respond. So there were a significant number of non-responders, and we are at the moment unable to identify who these non-responders are. That means that immediately after the procedure, we do not know if the patient will respond or not. In Beijing, at CIT 2012, I was sitting with the Medtronic boss whose company did the initial work in Australia, I told him that we certainly need to improve. We will find it hard to explain to our patients after the procedure, after spending the money and enduring the pain, that we do not know if we have helped the patient. 
From the initial experience, we know that despite the BP lowering, all of them still needed medications in the long term. Looks like the BP number came down but not fully. We are also concerned that the initial clinical trials on patients with resistant hypertension, had no control arm, meaning that we do not know if it is just a sham, placebo, effect.
Yes, at the moment it is shown to be quite safe. There were a few cases of renal artery dissection that required stenting, but we found that there was a significant amount of pain and these procedures required general anaesthesia.
Anyway, more and more companies are now coming out with more and more machines that can ablate more effectively and safely.
The clinical trials are still on going and we are await to see if this new technique will be proven effective. HTN-Symplicity III which has started enrollment will have a control arm, I am told.
In the meantime, we wait. We wait for more data. Yes, there is a new technique available, but at the moment, as I told my two patients, it is still largely experimental. Medications and life style modification is still the way to go.
In the future, who knows.

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