Burning away high blood pressure

Published On: Mar 18 2013 11:44:45 AM CDT
health, stethoscope

BACKGROUND:  High blood pressure is a serious condition that can lead to stroke, kidney failure, heart failure, coronary heart disease, and many other health problems.  Blood pressure is the tension of blood pushing against the walls of the arteries as the heart pumps blood.  One in three adults in the United States has high blood pressure.  People can have it for years and not even know it.  However, through time it can damage the heart, kidneys, blood vessels, and other parts of the body.  (Source: www.nhlbi.nih.gov)

 

BLOOD PRESSURE NUMBERS:  Blood pressure is measured as diastolic and systolic.  Diastolic refers to blood pressure when the heart is at rest between beats.  Systolic is when the heart beats while pumping blood.  More commonly, blood pressure numbers are written with the systolic number before or above the diastolic number, like 120/80 mmHg.  Normal blood pressure levels in adults are 120/80.  Prehypertension levels are 120-139/80-89. High blood pressure in stage 1 can range from 140-159/90-99.  High blood pressure in stage 2 can range from 160 or higher/100 or higher. Blood pressure levels are usually not consistent.  It can lower while sleeping and rise when awaking.  It can rise from being excited, active, or nervous.  If numbers stay in the prehypertension level, then the risk of developing high blood pressure increases.  (Source: www.nhlbi.nih.gov)

 

NEW TECHNOLOGY:  People who have high blood pressure can take steps to control it and reduce the risk for other health problems.  Lifestyle changes go a long way when controlling high blood pressure, but sometimes that’s not enough. Medications are generally prescribed by doctors to lower it, but depending on the stage and the patient’s general health medications may not be an option.  One of the body’s methods for controlling blood pressure involves the sympathetic nervous system.  It includes the major organs responsible for regulating blood pressure.  The kidney plays a major role in regulating blood pressure.  Renal nerves communicate information from the kidney to the brain.  People with hypertension have hyperactive renal nerves, which raises blood pressure.  Renal Denervation treatment is in clinical trials to learn whether renal denervation is safe and effective.  The Simplicity HTN-3 clinical trial will attempt to disrupt the hyperactive nerves by applying radio frequency energy near the nerves with an experimental medical device.  A single procedure inserts a tube in the groin and places the device in the artery leading to the kidney.  Multiple treatments are performed in each artery to disrupt the hyperactive nerves.  After treatment, the device is removed.  To find out if you are a candidate for this trial, visit http://www.symplifybptrial.com/candidate/ to take a short survey.  (Source: http://www.symplifybptrial.com/therapy/)

 

David Brown, MD, Interventional Cardiologist at The Heart Hospital, talks about a new way to treat high blood pressure.

How many people in the world are affected by hypertension?

Dr. Brown: There are a billion people in the world that have hypertension, high blood pressure that is not controlled. By 2025, there will be 1.6 billion people with hypertension. One-third of them are treated and not controlled with resistant hypertension and another third are untreated.

What does that mean? Are the numbers going to skyrocket with people having heart attacks and strokes?

Dr. Brown: Absolutely. For every 10 mmHg of blood pressure increase, the number of heart attacks doubles and strokes double.  For every reduction of 2 mmHg, there is a decrease in strokes by 10%.

Until now, was it kind of a hopeless feeling for you when you had someone who did not respond to medication?

Dr. Brown: Interestingly enough, it really wasn’t hopeless to physicians. If we go out and survey physicians right now every one of us will tell you, “Oh, I treat high blood pressure. I treat it really well. I am the best doctor treating high blood pressure.” It turns out; your patients still have high blood pressure. We found that out by doing this trial and looking at this treatment we are going to talk about. Because if you ask me, I would say “Oh, no, I have got this covered. I know how to treat blood pressure. I got my patients on the right medicines.” However, sometimes they do not take it; sometimes they are allergic to it; sometimes they are just aggravated about it and do not do it; and other times they are missing when their blood pressure is too high. So, we really have not controlled the blood pressure very well at all; even though we thought we did and even though we say we do.

What is the theory behind renal denervation? 

Dr. Brown: This is the first change in 100 years in the treatment of high blood pressure. I mean this is a disruptive technology. This is something that really changes the face of treatment of the disease. We have learned a long time ago that if you change some of the patterns of nerve information sending in the body, we can alter some of the metabolic processes and one of them is how blood pressure is controlled. We have used medicines to do it, but all the medicines have side effects. We see these patients who require 1, 2, 3, 4 or 5 medicines. They require maximum doses of medicines while not feeling well. So, the issue is with renal denervation, we thought if we can change that by having a treatment that brings blood pressure down significantly, then we might be able to remove some of those medicines; maybe even get off medicines all together.

This specifically targets the pathways from which organ?

Dr. Brown: This is primarily brain and kidney nerve flow and nerve impulses go both ways; some from the kidney feed to the brain, the brain back to the kidney, and the brain to the kidney. It is the part that controls what happens to sodium retention, your volume, and blood pressure. The kidney sends signals to the brain telling it what is going on and what to do. If those signals ramp it up too much and the result is hypertension, all kind of bad things happen.

How often have you done this procedure?

Dr. Brown: We have only done about 13 of these procedures.

Can you explain exactly how you do it? 

Dr. Brown: People are familiar with heart catheterization, but that is when we want to go look at things in the heart. We go look at arteries and look at blood flow. We do that by usually going through the groin or we can go through the radial artery.  It is under local anesthetic; the patient is awake. It is a small needle stick to get into the bloodstream. Well, this new procedure is the same thing. This is kind of like angiograms. So, we put a needle in the femoral artery in your groin. Once we get in there, we can put wires, catheters, balloons, and all sorts of devices in there. We go up and we take some pictures of the kidney arteries. It tells us the size of the arteries, where they branch and what they look like. Basically, we are looking to guarantee the safety of a procedure by following those pictures with an electrode-tipped catheter. It is basically a catheter with electricity where we can put it in the right spot in the artery and we are going to with low radiofrequency transmission, burn the nerves, and ablate them or knock them out. If we do that, we can change some of that feedback that is going on between the brain.

Is it that you are blowing out or not going to burn anything that is important?

Dr. Brown: This was discovered not quite three-quarters of a century ago. In the 1940’s and 50’s, this was done by surgeons whenever it was discovered that this could really have a big impact on decreasing this sympathetic nerve overdrive system. They went in and did it surgically. The problem was with surgery. They had all sorts of other complications. Now, we have a direct and easy way to get there and not harm any other organs and not hurt the kidney. With low frequency electricity, we can actually ablate that nerve. It is like cutting a wire. Once we do that, we can stop a lot of these bad impulses going back and forth.

There are so many wires in a car because all those wires go someplace and serve a purpose; does this not serve a purpose for anything? 

Dr. Brown: It does. It serves the purpose of conducting those nerve impulses that we talked about that go back and forth to the brain. However, what has happened is basically some evolution. We needed this nerve overstimulation or this sympathetic drive, sort of like the fight or flight adrenaline syndrome. Now, interestingly enough, it can still do that even after we ablate these nerves because you have plenty left and we many only reduce it by 20%, but we do not need those times and events anymore. The effect that it has on you and human life and what you do, is nonexistent. I mean you really cannot measure any difference and what you can do about all that.

Is there any risk to it? 

Dr. Brown: So, there is always a risk to every procedure. Every invasive procedure carries some risk, but the risks are low. We like to deal with risks that are below 1% or less than 100. There is always a risk of causing some burn in the muscle that causes some stenosis; that it may wind up needing to have a balloon or stent done to it. Every time we stick a needle in somebody, there is risk of infection, bleeding, and blood clots forming. However, these are all the common risks of every procedure we do and even the surgeries we do, but this is essentially noninvasive surgery. So it is a needle stick, minimally invasive without having to cut you open. 

Can you tell me about the 13 you have done?

Dr. Brown: This is not only a randomized trial, but it is a double-blind randomized trial. What does that mean? It means the patient does not know what treatment they get. It also means that we as physicians do not know what treatment they get. The intent of that is a very successful study done outside the United States to kick this off, but our FDA is always concerned about, how that really comes out and are people subject to sort of Madison Avenue advertising and marketing and can we convince somebody of the placebo effect. So, we have to eliminate that almost completely to know that that is really not what is going on. By doing that and not having anybody we go to the extent to put earphones on the patient, play music, and put blindfolds on them; so they cannot have any idea. We simulate the exact procedure. We simulate the burns and then we even give them a quiz that the FDA approved. It says, “Did you or did you not get real treatment?” So, we really do not want them to know. So, we do not know those results. We know the results from the previous studies. We know what happened before and they were dramatic. Blood pressures came down from an average of 160 to 128, 32 mmHg drop in your systolic blood pressure and that lasted and persisted now out to 3 years. It was 1 month, then 6 months, then a year. We have got the 2-year and 3-year results.

Is that the phase II clinical trial or?

Dr. Brown: I think this is still phase I clinical trial, but there was a first trial and a second trial. Now we have the trial being done in the U.S. and Europe that everybody is looking to see is this going to be the same result.

Can you see this procedure treating people with just slightly higher blood pressure to keep them off medication? 

Dr. Brown: I do not know and that is really the reason we are doing the trial and the reason trials are so important to medicine; so important in this country. The first thing is we take the worst and most difficult patients; the patients who need it the most, who have been unable to be controlled on 3 or more medicines. These patients are on 3, 4, 5 medicines. They have already been pushed to maximum dose and their blood pressure still is not controlled and that is the cohort or the group that the FDA picked out for us to do. They said, look, you get the sickest of the sick. You make it work there and you do not screw up, we will give you another shot at it. Then we will look at the intermediate group and then we will look at the lower risk group, but depends on how it comes out and we need to make sure there are no side effects and no complications to do that.

When you say that people who cannot control their blood pressure with medication or anything, they automatically assume the worst; they do not exercise, eat right, or they are not treating their bodies well. Is this genetic when it gets to that point?

Dr. Brown: No. There is an element of genetics certainly in all of this, but there is no question. It is a classic case of the better you take care of yourself, the better you are going to do, even if you are a person who is going to be normal or even if you are a person who is going to be hypertensive. Better eating, better exercise, weight drifting down, control of salt, and control of sodium intake, all those things have a significant role. Now, your point I think is very accurate that there are a lot of people who even when they do that and we get them on the right medicines, still have high blood pressure. It has been this evolution of genetics and those people do not have any way to go; so that is how we get there.

 

 

FOR MORE INFORMATION, PLEASE CONTACT:

 

Susan Hall

Media Relations Manager

Baylor Health Care System

(214) 820-1817

SusanH@BaylorHealth.edu