Monday, May 20, 2013


RDN stands for Renal Denervation.
RDN is a recently ( about 4 years ) discovered technique of trying to treat resistant hypertension ( not due to drug non-compliance ). I have written about it in the past.
Brief summary of the theory : Because there are sympathetic nervous fibers around the renal arteries, and many feel that this may be one of the reasons for resistant hypertension, ablating these sympathetic nerves may help to lower Blood Pressure.

 Early work was done by the Australians and Poles. They began with the use of the Symplicity catheter. This proved safe and successful. However, we have since learned that BP lowering is not instant, and may have to wait up to 6 months. That remains a big drawback with this technique.
                                 The Symplicity catheter by Medtronic, the pioneering company.
At the recently concluded American Society of Hypertension Annual Scientific meeting 2013,at San Francisco, Dr Murry Esler, the Australian pioneer, presented the 30 months follow-up data on the 37 patients from Symplicity HTN 2 study that was still on follow-up. Remember that this study started in 2010 and had enrolled 49 patients. Looks like 12 patients ( 24% ) were lost to follow-up, even in the good Australian Medical system. In these remaining 37 patients, Dr Esler was happy to report that the BP reduction seen at 6 months was still maintain. So also was the reduction in HR ( heart rate ). There was no increase in medication. Looks like the results are durable.
              I have always commented at International meetings that we are still adopting a wait and see attitude, although we note all the good results coming in, because of the issue basically of the various reasons for "Resistant Hypertension". In our Malaysian population, there seem to be a rather high percentage of "white coat" hypertension. The office BP measurement may not be a good way to diagnose and also to monitor hypertension treatment success or failure. Both Symplicity HTN 1 and 2 trials did not use Home BP monitoring or ambulatory BP monitoring. I am also rather concerned about the sham effect of this treatment procedure, because of an effect way to measure procedural success immediately. We have to await 6 months to see the BP settling. Is this a placebo effect from a "sham" procedure? The planned Symplicity HTN 3 trial, enrolling 500 patients will try and address some of these issues.
              Obviously many commercial company see a potential for business here. many RDN meetings have been held and more are being planned. 5 types of RDN catheter have already received CE mark approval. Although till date, non have received FDA approval. Dr Esler counted that about 40 more catheters are in the pipeline, showing us what the market potential is, as seem by the healthcare industry.
             For us, we will wait a little longer. I will be very keen to work with GPs in the Klang Valley and also some of the Renal Interventionist, to set up a Malaysia registry and gather our own experience. I think that that is the way forward. Copying data from first world countries have their usefulness but also many limitations. We are Malaysians.

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