New Medical Procedure: Destroying Nerves to Lower Blood Pressure (Part 1, The Trial)

by Heidi Stevenson

27 December 2009

A new surgical procedure claims to be a simple and easy cure for high blood pressure. It's so wonderful that it's being hyped as a replacement for drugs. Already, it's touted as revolutionary.

Dr. Paul Sobotka, Chief Medical Officer of Ardian, the company that developed the procedure, stated, "For the first time we can think of a cure for hypertension." (Just don't forget that he's paid to say things like that.)

However, a look at the first trial of the procedure, called renal denervation, which was reported in The Lancet,⁽¹⁾ shows that the results are far from thrilling and the trial itself suffers from significant flaws.

The Procedure

The purpose of the procedure is to destroy part of renal nerves, which transmit messages from the brain to and from the kidneys to signal a need to increase blood pressure. The medical term is renal nerve ablation. The idea is that partial destruction of the nerve limits its ability to transmit the signal, thus resulting in lowering of blood pressure.

The surgical procedure utilizes the Symplicity Catheter System, a product that is being developed by a new company, Ardian, which was formed specifically to develop it. Ardian is exceptionally well-financed, backed by Medtronic, a major medical appliance manufacturer, and venture capitalists. They had received $47 million by March of this year.

The doctor inserts a catheter into a blood vessel in the groin, and passes it up into the kidney. Once placed, radio frequency waves are used to heat the tip, causing limited damage to the blood vessel because of the blood's cooling effect, but burning the adjacent nerve. The tip of the catheter is then rotated and the procedure is repeated. It's done 4-6 times.

Injury to the blood vessel is believed to be minimal. The nerves, though, are damaged. This is the desired effect.

The procedure is considered day surgery. That is, the patient leaves the day it's performed.

The Trial

Fifty patients were included in the study: 45 receiving the procedure and 5 as controls, that is, the procedure was not done on them. Originally, 50 patients were selected, but 5 were rejected because of anatomical differences making the procedure impossible. Apparently, though, the rejected patients were used as controls!

All subjects were described as having "resistant hypertension", which was defined as systolic blood pressure greater than or equal to 160 mm Hg. They were taking at least 3 hypertension medications, including a diuretic. The average blood pressure reading at the beginning of the test was 177/101 mm Hg, and they were taking between 4 and 7 prescriptions.

The trial was performed while the patients were taking their drugs. All blood pressure readings were done while patients were taking their prescriptions.

Trial Results

The blood pressure readings were taken in a doctor's office at 1, 3, 6, 9, and 12 months post-procedure. The results are represented in this chart:

Not all patients responded to the treatment. According to the lead researcher, Professor Henry Krum PhD, 83% responded and 17% did not. Exactly what this means in terms of number of patients is...well, confusing. There were 45 who received the treatment. 83% of 45 is 37.35 and 17% of 45 is 7.65.

Then again, maybe that explains how doctors manage to think of medical problems as happening only to a body part—perhaps these researchers have a way of dividing a person into pieces for the purposes of their studies? I wonder how they manage to put them back together again when the studies are done.

Trial Problems

Aside from the patient parts question, there were a few other problems with the study.

One hundred percent of the trial's funding was provided by the product's manufacturer, Ardian, a company that is extremely well funded for the purpose of developing a single product. They are, obviously, going to design a trial that shows their product in the best possible light.

According to Krum, three treatment patients had to have their medications lowered during the course of the trial because their pressure had fallen so far, they'd developed hypotension symptoms.

Five of those who responded to treatment required an increase in drugs during the course of the trial. Clearly, the averages don't really tell the story. The only thing that's obvious is that some were able to lower the amount of medication taken, but apparently most didn't get to the point of normal blood pressure without meds.

No explanation was given for why blood pressure of the subjects who did not receive treatment increased—and by the end, increased signficantly more than the average improvement of those treated. If blood pressure normally increased this rapidly in hypertensive people, then most would not survive for long. I think that anyone diagnosed with hypertension would be advised to get his affairs in order, and it would be thought of as a terminal disease like cancer.

Perhaps that's why no readings are reported for the nontreatment group at the 12-month interval. Whatever the reason, this missing information might be significant. Of course, we don't know because we don't have it. Convenient?

Blood pressure was not taken at the optimal time, while the patient is asleep. The "white coat syndrome" can't take place then. Eoin O'Brien's concern about this issue was published in The Lancet⁽²⁾. He stated:

Specific details as to how blood pressure measurement was standardised are not given, other than that the latest recommendations of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure were followed. Whatever the detail, the method used could only favour the outcome in that office. Blood pressure is subject to the placebo and Hawthorne effects, regression to the mean, and most importantly to the white coat effect, all of which would favour a reduction in blood pressure over time.

The researchers didn't note any negative effects from the trial. However, except for a couple of tests related to kidney function, they don't appear to have been looking. That's not unusual in medical trials. The focus is very narrow—usually only on the body part being tested. So, serious problems are missed. Of course, there's motivation to miss them, since there's always a lot of money riding on the results. Any negative outcomes have the potential of preventing a product from coming to market.

The Biggest Problem of All

The most important concern of all is exactly the same problem that exists within most of modern medicine. It's the failure to look at the whole person. Why people develop hypertension is the real question. What's the benefit of decreasing blood pressure if a person's high blood pressure is caused by narrowing of arteries? Forcing a decrease in blood pressure would mean that cells all over the body would receive inadequate nourishment and waste removal. Could this be the real cause of problems from some cases of low blood pressure?

Obesity causes high blood pressure simply because the heart must pump blood through far greater distances, as much as miles more. How can lowering blood pressure be beneficial to people in this situation?

This problem, of course, cannot be resolved within modern medicine. It's inherent in the system itself—and is why it's possible to get away with trials like this. When the focus is not on a person's overall welfare, but is, instead, on a particular symptom, then the real point is completely missed. Health is a matter of an entire body acting in homeostasis. It isn't possible to make a person healthy by giving artificial chemicals called drugs or by destroying parts of the body, as the Symplicity Catheter System does.

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