Nurses are helping to evaluate a new device that controls blood pressure by stimulating the bodys natural blood pressure regulatory system.
Im extremely excited about this, because its so fascinating, says Karla Coco, RN, CDC, a nurse in the department of vascular surgery at Scott & White hospital in Temple, Texas. The thing I like about the device is it makes the body work better and do something that medicine alone cant.
Scott & White is screening patients to receive CVRx Rheos Baroreflex Hypertension Therapy System and expects to implant its first device soon as part of the multicenter Rheos Pivotal Trial. The system is designed to help people with hypertension not controlled with medication.
Hypertensive patients are at greater risk of stroke, heart disease and kidney failure, says Kerry Patterson, RN, a clinical research nurse at Rex Hospital in Raleigh, N.C. When you can reduce the blood pressure by 20 mmHg, its associated with a two-fold reduction in stroke and cardiovascular death risk.
Patterson feels excited about the device and its potential. The first patient at Rex has experienced good results. The patients systolic blood pressure decreased from 160 mmHg to 108 mmHg, at which time the voltage was turned down and her systolic pressure stabilized at 121 mmHg.
How the Device Works
The Rheos device provides a vibration to the baroreceptors in the walls of the carotid arteries in the neck. Normally, the baroreceptors report to the brain when blood pressure is higher than needed, and the brain sends signals to other parts of the body, including the heart, kidneys, and blood vessels, to act to lower the pressure.
It talks to the baroreceptors through electronic language, Coco says. Stimulating the baroreceptors causes the body to vasodilate [blood vessels] or talk to the kidneys [to release fluid] to decrease blood pressure.
Coco describes it as a way of helping the body perform better naturally.
Its like holding a match under a thermostat, Patterson adds. Even though the room temperature is 70 degrees and everything is cool, if you hold the match under an old-time thermostat, it will sense its hotter than it is, and the air conditioning will kick on.
That comes in handy when the baroreceptors no longer recognize a persons blood pressure as high and fail to send the proper signals to the brain.
In people who have had high blood pressure a long time, the body gets used to it. For whatever reason, the body is not able to compensate, explains Regina New, RN, MSN, regional manager for CVRx in the Carolinas. Twelve month data, from our feasibility trial, shows [the blood pressure] remains down and goes further down over time. Its not like the tolerance gets built up to the stimulation.
A previous European clinical trial with 12 patients found participants blood pressure decreased by 24 mmHg with active Rheos therapy. There were no serious, unanticipated adverse events.
CVRx aims to recruit 300 people with hypertension, whose disease is not controlled with medication. Patients must be taking and compliant with three antihypertensives, including a diuretic.
The intent of the study is not to change the medication; its to prove the efficacy of the device and the usage and safety, says Carol Stastny, RN, BSN, CCRC, research coordinator at the Cardiovascular Institute at Florida Hospital in Orlando.
The end point will assess whether the device results in a 10% reduction in blood pressure in the physicians office. Future studies will likely evaluate the devices ability to bring blood pressures down to target levels.
Prior to undergoing the procedure, the participant receives a carotid ultrasound and echocardiogram. Patients with ulcerative plaque in the carotid artery, tortuous arteries, autonomic neuropathy, bradyarrhythmias, chronic atrial fibrillation, or organ transplants are excluded. Patients also must have normal kidney function.
The surgeon makes three incisions, one near the collar bone, in which the pulse generator is placed, and one above the left and right carotid arteries, to attach thin lead wires around each baroreceptor site. Any drug that affects the baroreceptors cannot be used, says Stastny, explaining that anesthesia uses narcotics and barbiturate, not routinely used for surgeries.
While in surgery you have to make adjustments and stimulate the carotid baroreceptors, Stastny says. They find the best place to put the device.
Once the surgeon locates the most sensitive spot, the leads are sutured in place. The surgery takes three to four hours.
The patient spends one or two nights in the hospital for observation and incisional wound care.
When they wake up from anesthesia, their pressure goes right up, Stastny says. They go right back on all of their medicines.
A central line stays in overnight, and the research team conducts a dose response test, observing blood pressure and heart rate on the right, left and together while programming the device to the minimum through maximum voltage. A nurse monitors blood pressure and heart rate during the test.
Surgical risks are similar to other procedures: infection, hematoma at the site, death or stroke. Also due to their close proximity, the vagus and hypoglossal nerves potentially could be injured.
During surgery there is significant manipulation of the carotid area, says Susan Krenk, RN, BS, CCRC, a study coordinator at the Nebraska Heart Institute in Lincoln. Some patients complain of numbness in the neck or a tingling sensation or problems with their voice not being quite as strong during the first few months. Gradually over time, as the swelling decreases from the surgery, these things resolve.
The device is turned off and on and voltage adjusted externally. It must remain off for about a month to give the tissue time to heal and the swelling to subside. At that time, patients return and are blindly randomized at a two-to-one ratio to either have the device turned on or not during the first six months. Then all patients have the device activated. Patients check their blood pressure at home twice daily. The researchers will monitor participants monthly for one year and periodically thereafter for the rest of the participants lives.
Blood pressure is a moving target, New says. We are looking for the blood pressure over time.
Participants may need 24-hour monitoring. Blood pressure is taken in a calm room, with little talking. Repeat readings are taken. Patients have reported jaw pain or a tickle in the throat, which appears related to how sensitive the participant is to the voltage being delivered.
We will go up until they are symptomatic, New says. We program it below that level, so they dont feel it chronically.
New says, so far, benefits outweigh the risks in the patients selected. She expects the company may seek Food and Drug Administration approval to market the device in about three years.