International Circulation: Could you please summarize the meaning of resistant hypertension for us?

Dr. Markus Schlaich: We know these days that resistant hypertension is a very common problem.  The prevalence of resistant hypertension is probably somewhere between 20% to 30% of patients with hypertension， so it is of clear clinical relevance. Although we don’t have clear-cut data on the prognosis， we know based on other hypertension trials that patients with resistant hypertension are at an elevated risk for cardiovascular disease. It is therefore necessary to do much more research inthat area learn more about the prevalence， the prognosis， and the factors that contribute to resistant hypertension

International Circulation:  You mentioned in your talk earlier today， when a hypertensive patient comes into your clinic， what characteristics in the management of that patient or response to standard treatment would lead you to the diagnosis of their hypertension being resistant hypertension?

Dr. Markus Schlaich:  There is a clear definition of what we term resistant hypertension and that is uncontrolled blood pressure despite  a patientbeing on at least three antihypertensive drugs， typically including a diuretic and at an appropriate dose. Additionally， we have taken lifestyle modifications into account which is an important part of every type of hypertension treatment. When these treatment options have been exhausted and aggressive lifestyle intervention has been proven ineffective， then a diagnosis of resistant hypertension is appropriate.

International Circulation:  What are some of the big challenges you have experienced clinically in the management of resistant hypertensive patients?

Dr. Markus Schlaich:  First of all， there are several characteristics of these patients， commonly these are elderly patients or these are patients who are over-weight or mostly obese.  We know that patients with any type of renal disease or chronic kidney disease are typically more difficult to treat， as are patients with type 2 diabetes. Another factor that contributes substantially to the problem of resistant hypertension， is obstructive sleep apnea which seems to be a very common condition in patients with resistant hypertension， others include chronic kidney disease and volume overload. These are probably the most important factors that contribute to being unsuccessful in controlling blood pressure.

International Circulation:  In 2008， AHA has issued new guidelines for treating resistant hypertension. Could you describe for us the characteristics of the guidelines. And how your clinical experience may be similar to or add something different to the guidelines?

Dr. Markus Schlaich:  Well I certainly acknowledge the guidelines and think they have done a really good job based on the limited evidence  currently available.  Again I have to stress the point that we really have a need for additional research in this area. I think AHA came up with a very practical approach which really does make a lot of sense. What they suggest is once you have excluded the existence of pseudo-resistance following their algorhithm that you should treat these patients with a combination of inhibition of the renin-angiotensin system， that is either an ACE inhibitor or an angiotensin receptor blocker， a calcium channel blockers and an appropriate diuretic therapy. Then you have various options as add-on therapy and tye choice of additional drugs will  depend on the individual patient’s pathophysiology， comorbidities and potential intolernces.

International Circulation: You talked of some novel strategies for the treatment of resistant hypertension. During recent years， what is the progress on treatment of resistant hypertension?  First with regard to pharmacologic advances for treatment of resistant hypertension and secondly regarding the two novel surgical interventions you mentioned in your talk.

Dr. Markus Schlaich: Absolutely. We really need to understand the pathophysiology behind the condition to really treat it appropriately.  One of the major advances over the last couple of years， was the importance of increased levels of aldosterone which is an important mediator and commonly associated with resistant hypertension.  It is amazing how effective it can be to block aldosterone. Another interesting development is the use of endothelin A receptor antagonists which appears to be quite promising.  There are ongoing studies to investigate the effectiveness of these agents. Furthemore， I do think that we neglect the importance of the sympathetic nervous system and our own experience in our hypertension  center is that a relatively novel drug class， the so called selective imidazoline receptor agonists can be quite helpful in this scenario， particularly in obese patients or patients with sleep apnea because in these conditions sympathetic drive is substantially increased.  From a device point of view there are  two I intriguing and important developments， one is a device that stimulates the baroreflex and leads to a substantial reduction in blood pressure. One year following placement of this device， the investigators hav seen a reduction in systolic BP ofaround 20~30 mm Hg， which is quite substantial in resistant hypertensive patients. The second and very promising device relies on the importance of the sympathetic nervous system， in particular the renal sympathetic nerves. We are heavily involved in investigating a novel cathteter based approach to selectively denervate the sympathetic nerves along the renal artery via radio frequency ablation， thereby eliminating the autonomic nervous system’s stimulatory effect on the kidneys Our initial observations in 45 patienst treated with this novel  40 minute approach indicates a very favorable safety profile and a substantial and sustained redcution in blood pressure of around 30/20 mmHg in the majority of patienst. If controlled trials confirm these results， this procedure may provide new hope for many patients with difficult to treat hypertension and potentially cure less severe forms of hypertension.