Marie Joseph just might be the ideal candidate for an experimental treatment for drug-resistant hypertension.

For the past several years, she has been on five medications to treat her hypertension. But they haven’t had much of an impact. Joseph’s systolic blood pressure — the top number — is sometimes over 200, and has been as high as 228.

“My blood pressure makes me very stressed,” said Joseph, who is 51. “Whenever my blood pressure is high, my heart starts beating fast, like if I was feeling chest pains. A week ago I had to go to the hospital because my heart rate went up to 160 beats per minute. That’s very dangerous.”

Recently, both her cardiologist and nephrologist (a kidney specialist) at the University of Miami suggested that Joseph consider participating in a clinical trial for a new treatment for severe hypertension. In South Florida, both UM and the Baptist Cardiac & Vascular Institute are site locations for the Symplicity HTN-3 clinical trial. Medtronic is the medical company behind the national study.

Experts have long known that the kidney is a key player in blood pressure regulation. The kidneys are part of what’s called the sympathetic nervous system, which controls the “fight or flight” response.

But in patients with hypertension, the nerves around the kidneys are hyperactive and actually elevate blood pressure.

In the Symplicity trial, doctors attempt to lower blood pressure by using a radio frequency to disrupt or “zap” these hyperactive renal nerves. They do this by inserting a catheter into the patient’s groin and placing it into the artery that leads to the kidney. The catheter is then switched out for the experimental medical device, which emits radio-frequency energy through the artery walls to disrupt the nerves.

This process, which is completed in a single procedure, is called renal denervation.

“The idea is to go through the renal artery and injure those nerves without injuring other types of tissues,” said Dr. Barry T. Katzen, who directs the Baptist Cardiac & Vascular Institute.

The technology has already gone through trials outside the United States and has been shown to reduce high blood pressure in extreme cases of hypertension, although it is not a substitute for drugs. However, patients who have gone through the process have been able to lessen the number of medications they take.

“The studies in Europe have shown a decrease in blood pressure by as much as 30 millimeters of mercury over several months in patients that have had this technique done,” said Dr. Eduardo de Marchena, a professor at the UM Miller School of Medicine who is the primary investigator at UM for the Symplicity trial. “That means a patient with a systolic blood pressure of 180 could drop to 150.”

About 70 million people in the United States have hypertension, and most of those are able to control their blood pressure with one or more medications. But for about 5 to 10 percent of patients, the drugs don’t seem to have an impact.

“This [trial] has the potential to be transformational for that subgroup,” said Katzen. “If you reduce the systolic blood pressure you can significantly reduce the risk of heart attack and stroke. This is a potentially very important advance because those patients, right now, are offered no hope.”