Cardiovascular Medicine Innovations No need for high blood pressure?
No Need for High Blood Pressure Meds?
A novel treatment for drug-resistant hypertension
Electrical stimulation of “stretch receptors” surrounding the carotid arteries in the neck may prove to be the next treatment for drugresistant hypertension. Clinical researchers from the University Hospitals Harrington-McLaughlin Heart & Vascular Institute are part of an international research group examining the efficacy of this novel treatment. John Blebea, MD, Chief, Division of Vascular Surgery and Endovascular Therapy, University Hospitals Case Medical Center; Director, Vascular Center, UH Harrington- McLaughlin Heart & Vascular Institute; and Professor of Surgery, Case Western Reserve University School of Medicine, reports that this technique could enable patients to reduce or entirely discontinue use of their blood pressure medications.
Shocking treatment
Performed under general anesthesia, the procedure involves surgical placement of electrodes around both carotid arteries in the neck. The electrode wires are tunneled beneath the skin to an area under the collarbone where a battery and control unit are placed. “The device is very similar to a [heart] pacemaker and, indeed, has been termed a pacemaker for high blood pressure,” says Dr. Blebea. Electrical stimulation of the stretch receptors that surround the carotid arteries, known as baroreceptors, sends an electrical signal to the brain, causing it to use its natural pathways and mechanisms to relax blood vessels and lower blood pressure – the baroreflex. “The result is seen immediately after the device is turned on,”says Dr. Blebea.
About 72 million adults in the United States suffer from hypertension, defined as having a systolic blood pressure of 140 mm Hg or higher or a diastolic blood pressure of 90 mm Hg or higher. Of these, about 4 million adults (approximately 6 percent) suffer from drug-resistant hypertension. This is a form of the disease that does not
respond to normal treatments such as reducing salt intake or using various combinations of medications. John Blebea, MD, Chief, Division of Vascular Surgery and Endovascular Therapy, University Hospitals Case Medical Center; Director, Vascular Center, UH Harrington-McLaughlin Heart & Vascular Institute “We are not certain why some individuals are resistant to present therapies,” says Dr. Blebea.
Two preliminary trials of the baroreflex stimulators, however, yielded encouraging results. “For patients who were on an average of five medications, the procedure reduced their systolic blood pressure by 37 mm Hg. This result was observed even after the device had been in place for three years,” Dr. Blebea says. The Rheos® Baroreflex Hypertension Systems trial, sponsored by the developer of the device, CVRx Inc., is being conducted at 30 clinical sites and is planned to include 300 patients. Individuals enrolled in the study need to be over 21 years of age and have blood pressure that is at least 160/85 mm Hg. The study is currently in the Pivotal Clinical Trial stage of testing, which must be completed before final approval can be issued by the Food and Drug Administration. The device has already been approved to treat drug-resistant hypertension in Europe, but it will not be marketed there until the present study is completed.
Potential for additional applications
“If the device is demonstrated to be efficacious in patients with resistant high blood pressure and approved by the FDA, I see the possibility that it will be used in patients with other conditions,” says Dr. Blebea. Another trial has begun to test the baroreflex stimulator device in patients with congestive heart failure. “Preliminary results in some patients show that their heart function has improved,” Dr. Blebea notes, “so there are additional exciting possibilities for application of this technology.”
