A Medical Device Daily

Preliminary data from European and U.S. early clinical trials evaluating the safety and effectiveness of the Rheos system from CVRx (Minneapolis).

CVRx says that Rheos is the first implantable device designed to control hypertension, were presented at this year's scientific sessions of the American College of Cardiology (ACC; Washington) earlier this week by Peter de Leeuw, professor of medicine/ hypertension at the University of Maastricht (Maastricht, the Netherlands).

CVRx said the findings show a "significant reduction" in blood pressure in patients with drug-resistant hypertension who have a systolic blood pressure of 160 mmHg or greater, despite being on at least three anti-hypertension medications.

By applying electrical pulses to the carotid artery, the Rheos system triggers the body's baroreflex system, which causes the heart to pump more slowly, arteries to dilate and the kidneys to excrete more fluid.

CVRx said that at least 2 million Americans are unable to bring their blood pressure under control, and so the device could find wide use if its efficacy is confirmed in larger trials.

"We are pleased with the early clinical results to date and are optimistic that this novel treatment approach could offer a new option for patients with drug-resistant hypertension," said de Leeuw, the study's principle investigator.

Systolic blood pressure was reduced by an average of 21 mmHg, and diastolic blood pressure was reduced by an average of 16 mmHg. A 20-point reduction in blood pressure is typically associated with a 50% lower risk of heart attack and stroke, according to the company.

The Rheos implants were well tolerated, and there were no "unanticipated" adverse events related to the system or procedure.

Nadim Yared, president/CEO of CVRx, said, "We are expanding the scope of the Rheos system evaluation with a pivotal trial that is now under way. We have begun enrolling patients and look forward to advancing our understanding of the Rheos system and therapy."

In October 2006, CVRx received conditional investigational device exemption (IDE) approval from the FDA to begin a U.S. pivotal clinical trial that is evaluating the safety and effectiveness of the Rheos system in a much larger number of patients. The study will be conducted at up to 50 medical sites. Those enrolled need to be resistant to treatment with at least three anti-hypertension agents, including a diuretic, and their systolic blood pressure must be greater than or equal to 160 mmHg. Results are intended to support the premarket approval application to the FDA.

In other ACC conference news:

• Abiomed (Danvers, Massachusetts) reported the release of data on its Impella 2.5. The study, titled "Preliminary Experience of the MACH 2 Trial: Safety and Feasibility of Left Ventricular Support With the Impella Recover LP 2.5 Device in Patients With Acute ST-Segment Elevation Myocardial Infarction," found that the Impella 2.5 improved cardiac function for pre-shock acute myocardial infarction (AMI) as compared to conventional routine care including intra-aortic balloon pump (IABP) therapy.

"We have already published on the safety of the Impella 2.5 technology. Today we provide the first human study that documents the benefit of the Impella 2.5 to improve the left ventricular function post acute myocardial infarction as evidenced by the left ventricular ejection fraction," said J.P.S. Henriques, MD, a cardiologist at the Academic Medical Center (Amsterdam, the Netherlands).

The 20-patient study looked at patients who were admitted for an AMI with hemodynamic instability, had the necessary procedure to re-open the blocked artery, and then received the Impella 2.5 or standard routine care including intra-aortic balloon-pump for a few days.

The preliminary results showed that patients supported by the Impella 2.5 technology had significantly improved cardiac function at three days and four months after the heart attack as compared to the control group. The preliminary results showed an increase in ejection fraction of 9% and 13% at three days and four months, respectively in the Impella 2.5 group as compared to 2% and 5% in the control group.

In addition, a study presented by Melchior Seyfarth, a professor of cardiology at Deutsches Herzzentrum, Technische Universitaet (Muenchen, Germany), compared the effectiveness of the Impella 2.5 and IABP.

Seyfarth and his colleagues randomly assigned 26 patients who were in shock following a heart attack to circulatory support with the IABP or the Impella 2.5. They found that after 20 minutes of support, the amount of blood being circulated by the heart was significantly better in the group with the Impella 2.5. Cardiac output increased by 1.1 L/min in patients supported by the Impella pump, as compared to 0.2 L/min with the IABP. Investigators also noted a trend toward better mean arterial pressures with the Impella pump, which produced an increase of nearly 9.8 mmHg, as compared to a decrease of 1.2 mmHg with the IABP.

The Impella 2.5 is a ventricular assist catheter, which is inserted percutaneously in the catheterization laboratory via the femoral artery into the left ventricle.

Up to 2.5 liters of blood per minute are delivered by the pump from the left ventricle into the ascending aorta, providing the heart with active support in critical situations.