Patients with hypertension whose blood pressure cannot be brought down to safe levels despite taking three or more medications may have some relief coming their way. An innovative, first-of-its-kind clinical trial for a device representing a dramatic shift in treatment approaches for the toughest-to-treat patients is currently being conducted at NewYork-Presbyterian Hospital.
Clinical trials of the Symplicity renal denervation system from Medtronic are underway at both NewYork-Presbyterian Hospital/Weill Cornell Medical Center and NewYork-Presbyterian Hospital/Columbia University Medical Center, which is the leading clinical-trial site in metropolitan New York. If successful, this investigational procedure—which deviates from traditional pharmaceutical therapies in favor of a minimally invasive procedure that aims to down-regulate overactive nerves in the body that can cause rising blood pressure—could turn the tide for the many Americans affected by treatment-resistant hypertension.
"Hypertension is a serious health problem, and those with drug-resistant hypertension are at the greatest risk of developing organ damage, including heart attack, stroke and death," says Dr. Ajay J. Kirtane, an interventional cardiologist and chief academic officer of the Center for Interventional Vascular Therapy at NewYork-Presbyterian/Columbia University Medical Center. Dr. Kirtane is leading the study at NewYork-Presbyterian/Columbia. "In earlier studies, the Symplicity renal denervation system reduced systolic blood pressure by an average of 33 millimeters, a remarkable amount for patients with such severe hypertension. If the results are duplicated in this pivotal clinical trial, we may have discovered an effective treatment that will help millions of Americans."
"The Symplicity renal denervation system may someday be an attractive alternative for patients in the U.S. who have uncontrolled hypertension despite treatment with many medications," says Dr. Samuel J. Mann, a leading hypertension specialist at NewYork-Presbyterian/Weill Cornell and professor of clinical medicine at Weill Cornell Medical College, who is leading the study at NewYork-Presbyterian/Weill Cornell.
Researchers think that hyperactivity of the sympathetic nervous system, which connects the brain, heart, blood vessels and kidneys—each of which plays an important role in blood pressure—contributes to resistant hypertension. The Simplicity renal denervation system seeks to reduce the drive of the sympathetic nervous system by preventing it from sending out erroneous signals to the brain to increase blood pressure.
In the Symplicity system, a catheter is introduced through a very small incision in the groin and is threaded up into the renal arteries that supply blood to the kidneys. Once in place, the catheter sends out radio waves at a preset frequency generated by a proprietary generator, which target the sympathetic nerves without damaging the surrounding blood vessels. The catheter is removed once the radiofrequency waves have been delivered at multiple locations along the artery.
Affecting about 76.4 million people over the age of 20 nationwide, hypertension is a common cardiovascular disorder in which blood-pressure levels are abnormally elevated—systolic blood pressure of 140 or greater or diastolic blood pressure of 90 or greater—over a sustained period of time. Hypertension is considered to be treatment-resistant when a patient's blood pressure remains high despite treatment with three or more antihypertensive medications.
The U.S. Food and Drug Administration approved the Symplicity HTN-3 study protocol in July 2011. NewYork-Presbyterian Hospital is currently enrolling patients for the study, which altogether will randomize 530 patients to receive either renal denervation combined with antihypertensive medications or treatment with antihypertensive medications alone. To qualify, patients must meet certain criteria, including having systolic blood pressure of at least 160 mmHg in the physicians's office despite treatment with adequate doses of at least three antihypertensive medications.