February 27, 2012 Contact: Sue Crosson-Knutson 312-334-2311 firstname.lastname@example.org
CHICAGO–Currently GORE® TAG® devices are often used for stent grafts which repair of the thoracic aorta. Infrequently complications from infolding can occur, primarily in young trauma patients and is secondary to excessive oversizing and severe proximal aortic angulation. A new study published in the March issue of the Journal of Vascular Surgery® reports that there clearly exists a continued need for these devices and improvements are continuing to be made in the device field.
The study researchers evaluated the incidence, predictors and outcome of the complication of infolding with GORE® TAG® Thoracic Endoprosthesis device to better understand the factors that might help predict these device-related complications. Co-author Karthikeshwar Kasirajan, MD, a surgeon from East Bay Cardiovascular and Thoracic Associates in Concord, Calif., said complications are partly due to the unavoidable proximal angulation and increased flow-related forces. He noted that researchers reviewed all device complaints reported to W. L. Gore and Associates in Flagstaff, Ariz. and other events related to device infolding on or before December 2008.
From 1998 through December 2008, device infolding was reported in 139 patients (mean age, 40 and 73.4 percent male) from 33,289 device implants (reported incidence, 0.4 percent). Sixteen patients received no intervention after the diagnosis of device infolding; all were asymptomatic. The other 123 patients underwent 135 interventions. Of these, 30 patients (24 percent) underwent open surgical conversion and complete or partial endograft removal.
Other interventions included a variety of endovascular techniques including large balloon-expandable stent(s) in 40 percent, relining with additional endograft(s) in 31 percent and repeat ballooning in seven patients. Events were noted in implants for trauma (60 percent), dissection (19 percent), aneurysm (10 percent), other (9 percent) and unknown (2 percent) etiologies. Seventy-seven percent of patients with available imaging had an average oversizing of nearly 33 percent. Of reported patients, 51 percent were asymptomatic, with the diagnosis being made on routine chest imaging and the time to diagnosis was 76 to 222 days (median, 9.5 days).
Ten patients died after device infolding, all after one or more attempts to repair the infolded device: five died of symptoms related to the infolding and five secondary to the intervention undertaken to correct the device infolding.
Dr. Kasirajan added that reporting physicians and local company representatives were contacted when necessary, to assemble all available imaging, data and outcomes related to these case reports. Computed tomography images were reviewed when available to confirm aortic landing zone diameters, which were subsequently compared with the implanted device size.
Researchers noted that TAG® devices were designed for the aneurysmal patient population and, as a result, are at times not capable of withstanding the forces applied when used in young trauma patients. They believe that the next-generation thoracic stent grafts should include features that allow for their broad application to etiologies other than aneurysms, such as trauma and dissection. “These features will include greater radial force, better conformability to the inner curvature of acutely angulated aortic arches, greater tolerance for device oversizing and smaller device diameters,” said Dr. Kasirajan.
“One such device is the Conformable GORE® TAG® Thoracic Endoprosthesis,” explained Dr. Kasirajan. “It has been designed to have improved flexibility with more generous oversizing windows of between 6 percent and 33 percent. In many instances this allows for two or three different device diameters to be used within the IFU for a given aortic diameter. It also includes both tapered and smaller device diameters that are designed to treat aortas with inner diameters as small as 16 mm.”
Researchers said that the proximal and distal ends of the device have also been redesigned, with the removal of the flares and the addition of a short length of uncovered stent apices on the device’s proximal end. “Thousands of these devices have been implanted worldwide, with no reported incidences of device infolding or compression despite its application in patients with traumatic transaction and aortic dissection,” added Dr. Kasirajan.
In January 2012 the U.S. Food and Drug Administration approved the Conformable GORE® TAG® Thoracic Endoprosthesis for endovascular repair of isolated lesions of the descending thoracic aorta, including traumatic aortic transections. Extensive clinical research has been conducted with the device in the areas of aneurysm, trauma, and acute complicated type B dissection. Currently there is an ongoing U.S. trial investigating its use for the treatment of acute dissection.
Researchers noted that until this device and other next generation devices become available with clinical data for use in diverse patient populations, caution should be exercised when using thoracic aortic stent grafts for “off-label” indications. As a result, they said, future device designs should consider the compression failure mode when being designed in order to help prevent such events.
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