#1 Catheter-Based Renal Denervation to Control Resistant Hypertension

Overview

When blood pressure is elevated—140/90 mm Hg or higher—a person will receive a diagnosis of hypertension or high blood pressure. It’s important to prevent any rise in blood pressure. The top number in a blood pressure measurement is called systolic and the smaller number is diastolic pressure. Damage to the body can begin at levels of 110/70 mm Hg, which is below optimal and long before hypertension is ever diagnosed.

Today, one in three adult Americans has hypertension, which puts them at significant risk for strokes, heart attacks and kidney failure. In fact, more than two thirds of individuals who have a first heart attack and three quarters of those who have a first stroke have hypertension. Hypertension—not smoking—is the number one risk factor for death in the world.

Resistant hypertension is now a major health problem. By definition, this is high blood pressure that does not respond to medical treatment and remains elevated despite lifestyle changes and administration of an optimal three-drug regimen that must include a diuretic. A person who needs to take four or more medications to reach their blood pressure target is also considered to have resistant hypertension.

It’s estimated that 20 to 30 percent of all patients with hypertension fall into this resistant hypertension category. In the past, there has been nothing to do that could adequately help these patients. Until now, that is. There is presently a way to control resistant hypertension without drugs—and the results appear to be long lasting.

The renal sympathetic system, which consists of the small nerves that carry the signal from the brain to the kidney and back from the kidney to the brain, plays an important role in the regulation of blood pressure levels. Researchers have now found that disruption of these nerve fibers has a positive effect on blood pressure levels.
Renal denervation is a new 40-minute procedure performed in a hospital catheterization laboratory in which a catheter-based probe is introduced through the femoral artery in the upper thigh and is threaded up into the renal artery near each kidney.

Once in place, the tip of the catheter delivers multiple two-minute treatments of low-power radio-frequency energy to affect the surrounding sympathetic nerves.

In the recent Symplicity HTN study of 106 adults with resistant hypertension, the first human randomized controlled trial of renal denervation, 54 patients received oral medications and 52 underwent renal denervation. After six months, 39 percent of patients receiving renal denervation reached target blood pressure and, overall, 50 percent of patients showed a measurable benefit from the intervention.

Systolic blood pressure fell an average of 32 mm Hg and diastolic blood pressure fell an average of 12 mm Hg and the effects lasted at least two years. Patients in the control group who took anti-hypertensive medications alone had blood pressures that did not vary from baseline.

Not only is renal denervation a new treatment avenue that causes significant drops in blood pressure, it also has shown promising results for treating chronic kidney disease, insulin resistance, and heart failure.

Where Are They Now

For every drop of 20 mm Hg in systolic blood pressure, the risk of cardiovascular disease is cut in half. At the annual European Society of Cardiology meeting in May 2012, multi-center study results of 46 patients with drug-resistant hypertension experienced an average 22 mm Hg drop in blood pressure after undergoing renal denervation, and another 6 mm Hg drop at the 30-day study milestone. Three months later, lowered blood pressure remained stable for all study subjects. There are currently five companies manufacturing renal denervation devices, which are only available in Europe.

While the initial US study failed to meet efficacy endpoints in 2014, the advancement of new devices for renal denervation creates high hopes that efficacy will be reached in the numerous ongoing US and European trials. Professionals along with patients have not given up on renal denervation becoming a successful treatment option for those with refractory hypertension. A new study supports that renal denervation can treat hypertension and suggests that failures may be due to incomplete procedure.

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