Experimental technologies are providing innovative solutions to cardiology's clinical and research challenges, according to studies presented today at the American College of Cardiology's Innovation in Intervention: i2 Summit 2007 in New Orleans, La. Innovation in Intervention: i2 Summit is an annual meeting for practicing cardiovascular interventionalists sponsored by the American College of Cardiology in partnership with the Society for Cardiovascular Angiography and Interventions.
Among the new technologies are an implantable device that stimulates the body's own regulatory systems to control high blood pressure that is unresponsive to antihypertensive medication, a computer that improves the results of angioplasty by automating balloon inflation, and an X-ray visible microcapsule that simplifies the delivery and tracking of stem cells to tissues in need of new blood vessels.
Chronic Treatment of Resistant Hypertension With an Implantable Device: Preliminary Results of European and United States Trials of RheosTM Baroreflex Activation (Presentation Number: 2406-3)
An investigational device that electrically stimulates the body's natural pressure-regulating sensors is proving effective for long-term control of high blood pressure, or hypertension, in patients who do not respond adequately to more conventional treatments.
"In our part of the world, about one percent to five percent of hypertensive patients are treatment-resistant," said Dr. Peter de Leeuw, a professor of medicine at University Hospital Maastricht, Maastricht, the Netherlands. "Without further options, they face a high chance of life-threatening complications such as heart attack, stroke, and heart and kidney failure."
The Rheos Baroreflex Hypertension Therapy System (CVRx, Minneapolis) consists of a pulse generator—a device the size of a pacemaker that is implanted under the skin near the collarbone—and wires that carry electrical impulses to the carotid arteries in the neck, where the body's pressure sensors, or baroreceptors, are located. The brain interprets the electrical impulses as a rise in blood pressure and activates the body's natural responses for bringing blood pressure back down, including relaxation of blood vessels, slowing of the heart rate, and increased fluid excretion by the kidneys. Previous studies suggested that the Rheos device significantly reduced both systolic blood pressure (the pressure in the arteries when the heart is contracting) and diastolic blood pressure (the pressure when the heart is relaxed and filling with blood).
To evaluate long-term effectiveness, Dr. de Leeuw and his colleagues combined data from a total of 27 patients enrolled in the U.S. Rheos Feasibility Trial and the European Device Based Therapy of Hypertension Trial (DEBuT-HT). All patients had a systolic blood pressure of 160 mmHg or more, despite at least three antihypertensive medications. (A systolic blood pressure of 120 mmHg is considered normal). Six months after initiation of treatment with the novel implantable system, systolic blood pressure was reduced by 21 mmHg, on average, and diastolic blood pressure, by 16 mmHg—both highly significant improvements.
The Rheos system continued to be effective in controlling blood pressure even after one year, Dr. de Leeuw said. Investigators have since launched a multicenter, randomized study to further assess long-term benefit.
Dr. de Leeuw will present this studay on Sunday, March 25, at 1:30 p.m. in La Nouvelle Orleans C.
Improved Outcomes in Patients Undergoing Coronary Stenting With Use of a Gradual Computerized Angioplasty Protocol: A Prospective, Randomized Trial (Presentation Number 2406-7)
A computer-driven device that gradually inflates a balloon and stent inside a narrowed coronary artery significantly reduces the long-term risk of renarrowing, or restenosis, and its complications, including heart attack. Dubbed CAPSID, the Computerized Automatic Pressure Sensor and Inflator Device is an alternative to manual techniques, which can injure the artery wall.
"CAPSID was developed to minimize trauma to the vessel wall and, therefore, reduce restenosis," said Professor Teddy Weiss, director of the intensive care unit at Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem, Israel. "Our findings using the CAPSID device with bare-metal stents are similar to results obtained with drug-eluting stents, without their increased cost and without the increased risk of late clotting that has recently caused some concern in the cardiology community."
To evaluate the effectiveness of the computerized device, Dr. Weiss and his colleagues recruited 300 patients scheduled for stenting, randomly assigning half to conventional manual balloon and stent inflation and half to CAPSID inflation. About half of patients in each group had unstable coronary disease and 90 percent of patients in each group were treated with bare-metal stents. One-year follow-up, which has been completed for 293 patients, showed that CAPSID use significantly reduced the rate of heart attack (1 % vs. 8 %) and the need for a repeat procedure to reopen the coronary artery (5 % vs. 12 %).
"Our results imply that the use of the CAPSID device may improve outcomes in patients undergoing stenting," Dr. Weiss said. "This system should reduce health-care costs by reducing the need for expensive drug-eluting stents and the need for repeat procedures."
Dr. Weiss will present this study on Sunday, March 25, at 2:20 p.m. in La Nouvelle Orleans C.
An Emerging Technology for Managing Peripheral Arterial Disease: An X-ray Visible Mesenchymal Stem Cell Delivery and Tracking System (Presentation Number: 2406-5)
A novel technique that transports therapeutic stem cells in a multilayer microcapsule not only protects the cells from attack by the body's immune system but also enables them to be seen on X-ray. The first study of its kind, it offers a model for using X-ray visible microcapsules, dubbed XCaps, for tracking the delivery, survival and function of donor stem cells in the treatment of cardiovascular disease.
One example of a potential use for Xcaps is limb ischemia, a critical shortfall of blood and oxygen to the tissues in the leg and foot as a result of clogged arteries in the legs.
"In acute ischemia, you don't have the luxury of taking stem cells from the body and waiting two to three weeks to culture and expand them in the laboratory," said Dara L. Kraitchman, VMD, Ph.D., an associate professor of radiology at Johns Hopkins University School of Medicine in Baltimore. "Ideally, we'd like to be able to take donor cells off the shelf, make them X-ray visible, protect them from the immune system, and deliver them precisely where we want them to be," said Dr. Kraitchman.
The XCaps are created by coating donor stem cells with layers of alginate, a compound that provokes little immune response; barium, a contrast agent that makes the microcapsule X-ray visible; and poly-L-lysine, which holds the microcapsule together. The outer coating is made up of another layer of alginate.
The Johns Hopkins team evaluated the XCaps in rabbits, first creating XCaps from the stem cells of male rabbits. They then replicated the effects of severe peripheral arterial disease and limb ischemia by using a catheter to insert a platinum coil in the artery supplying blood to the hind limb of 13 female rabbits. One day later, the female rabbits were randomly assigned to receive an injection of XCaps with stem cells, XCaps without stem cells, stem cells alone or a sham injection. Researchers found that XCaps were visible on X-ray both immediately after injection and at two weeks. They also observed that the animals grew a large number of new blood vessels in the ischemic zone.
"The nice thing about XCaps is that you can see each individual capsule very clearly on X-ray," said Dr. Kenyatta Cosby, a postdoctoral fellow at Johns Hopkins School of Medicine in Baltimore. "We also observed no accumulation of fibrous material around the capsules, which suggests a minimal immune response."
Dr. Cosby will present this study on Sunday, March 25, at 1:50 p.m. in La Nouvelle Orleans C.
The American College of Cardiology (www.acc.org) represents the majority of board certified cardiovascular physicians in the United States. Its mission is to advocate for quality cardiovascular care through education, research, promotion, development and application of standards and guidelines- and to influence health care policy. ACC.07 and the i2 Summit is the largest cardiovascular meeting, bringing together cardiologists and cardiovascular specialists to share the newest discoveries in treatment and prevention, while helping the ACC achieve its mission to address and improve issues in cardiovascular medicine.