Sunday, September 23, 2012


Yesterday, I attended the Symplicity Renal Denervation ( RDN ) Initial Training course, conducted by Medtronic International at the KL Hilton Hotel. They had assembled about 50doctors there, who had interest in RDN. They cam from Malaysia and also the ASEAN countries. I could recognise some Thais there.
Renal Denervation or RDN for short, is a new ( well 3 years old ) way of treating Resistant Hypertension. It is based on the principle that the Sympathetic Nervous system has a large role to play in Resistant Hypertension, and that there is a sympathetic nerve plexus around the renal artery. Basic science research shows that these nervus plexus are situated in the adventitia of the artery wall, and that they can be ablated ( or destroyed ) by energy passed through the arterial wall.  Damaged to the Sympathetic Nerve plexus lowers BP and stimulation of them increases BP. A few years back, Medtronic bought over a small company called Ardian, who were doing some research in this field. By so doing, they own the patent to the Ardian machine, and Medtronic then started to do clinical trials based on these principle. Much of the research was done in Australia, by Dr Esler, and also in Poland and Germany. Three years ago, they initiated the Symplicity HTN 1 trail, which now has 60 or so patients on follow-up ( now over 36 months ), and the Symplicity HTN 2 trail with about 18 months follow-up. I hear that they are also recruiting for Symplicity HTN 3 trial which will have a "placebo" arm. ( I am not sure how they can have a placebo arm, when the sham op arm must induce pain??


The good point about RDN is that it affords a good way of dealing with patients whose BP cannot reach target, despite 5 medications. We define "Resistant Hypertension" as hypertension that cannot be controlled, to target levels, despite 3 or more medication ( one of which must be a diuretic, in possible an aldosterone antagonist ). The procedure itself is fairly simple and any trained vascular interventionist should be able to be trained. It cost about Euro 6-7,000 ( I hear locally, it is being tried and cost about RM 20,000. It does require analgesia and some heavy sedation besides local anaethesia, and a risk of 1%. It does require overnight stay and at the moment, it is done trough the groin route.

However, as I sit there and listen to the experts, having heard many of these information before, I quickly realise that there were substantial concerns and need much more work. I knew from my own reading, that there was no immediate marker of procedural success. We ablate, 4-5 times around the renal artery ( about 3 mins interval ), induce pain in most patients, cost them about RM 20,000 with a 1% risk, and am not sure if it will work for the patient. There is a 20-25% non-responder rate, and you will not know the responders, until 6 months at least, if not 2 years. As I raised at the meeting, what we are saying to our patients after the RDN procedure is that, trust me I did a good job!!! Is that reasonable? Right after the procedure, they still have to continue all the medications too. Many of the patients later, after months or years, can be slowly weaned off their medication.
Maybe it is my cardiac interventionist background that after we have dilated and stented, we have pristine pictures to show that we have successfully treated the stenosis. I urged the innovaters and investigators to find a way, ? biochemical markers, to show our patients that we have done some good.
I was also very concerned that the definition of "resistant hypertension" is very loose. There is the issue of "white coat hypertension", the issue of non-compliance with medication ( so common in our local population ), the issue of how BP is measured ( home monitoring as opposed to office monitoring - the fear of the doctor ). What is even worse, with such a " grey procedure", is that the diagnostician is also the therapist. He decides that it is resistant hypertension, he does a RDN and after the RDN, he tells the patient, you are OK, keep taking the medication. Trust me, you will be OK!. That to me does not sound reasonable at the moment.
Anyway, Medtronic is going ahead to promote, and I am sure that many interventionist will jump on the wagon.
I urge caution at the meeting, for us to form a national program, to set standards of care for "resistant hypertension" and to initiate a planned RDN program, so that patients will not be mislaid.
But alas, I fear that this lone voice is a voice in the wilderness.

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