Clinical Study of Thoracic Aortic Aneurysm Exclusion

A vascular aneurysm is a permanent, localized dilatation of a blood vessel at least 1 1/2 to 2 times the normal vessel diameter. The aorta is the most frequent site for aneurysms, with approximately 10% of aortic aneurysms located above the renal arteries in the thoracic segment. Thoracic aortic aneurysms (TAAs) are less common than abdominal aorta, however, detection of TAAs is increasing, perhaps due to an aging population, increased diagnostic capability or an increase in prevalence. Untreated thoracic aneurysms can be life-threatening. As many as 78% of untreated patients with TAA die within 5 years after diagnosis, most often from rupture of the aneurysm. Conventional surgical treatment, either tube graft placement or patch aortoplasty, is a high risk surgical procedure. Repair of the thoracic descending aorta is performed with a thoracotomy and cross-clamping of the aorta, with or without a shunt by-pass to maintain distal perfusion. As an alternative to conventional surgery, a less invasive endovascular procedure has been developed that may be used to treat certain aneurysms. A collapsed stent-graft, a metal stent coupled with a fabric graft, is introduced into the vasculature, advanced to the size of the aneurysm, and deployed to span the aneurysm. The device creates a new aortic lumen, excluding the aneurysm sac from blood flow while maintaining flow within the stent-graft. This less invasive technique is designed to prevent or decrease the need for open surgery, to reduce the need for blood transfusion, to decrease the use of anesthetics and other drugs, and to speed recovery time. A reduction in intensive care and total hospital stay should result, leading to an increase quality of life following the procedure and a reduction in cost. The primary objective of this investigational plan is to determine the safety of the Valiant endoluminal device when used to exclude thoracic lesions: true descending thoracic aortic aneurysms, dissections, penetrating ulcers, traumatic transections and traumatic and degenerative pseudoaneurysms from blood flow in high risk and low risk patients who are candidates for endoluminal repair. Patients should be heparinized during the implant procedure (recommended activated clotting time is 200-300 seconds). During implantation of the Valiant endoluminal stent-graft, the pre-implant angiogram and CT scan are used together with (on-the-table) intravascular ultrasound (IVUS), digital subtraction angiography (DAS), roadmapping, and angiography for proper implant positioning. The Valiant endoluminal stent-graft endoprosthesis is inserted by delivery catheter and introducer sheath via a surgical cutdown (e.g., external iliac artery, femoral artery, common iliac artery conduit, etc.) approach. The introducer sheath and delivery catheter containing the stent-graft is inserted over a guidewire and advanced into the aorta and above the aneurysm. With the delivery catheter in the correct position, the introducer sheath is then withdrawn further until the stent-graft is completely deployed. A separate stent-graft balloon catheter system is provided with the device and may be used along the full length of the implanted device to model the springs against the vessel wall and to unravel possible wrinkles in the graft fabric. After deployment of the stent-graft, angiography is performed to verify implant position and to check for the presence of endoleaks. Subjects will undergo an evaluation of the Valiant endoluminal stent-graft to determine the safety and efficacy of the device as indicated by the adverse event rate, and to determine the risk factors that are most predictive of a successful outcome when used to exclude thoracic aortic aneurysms that require suprarenal fixation in high risk and low risk patients. Follow-up will be completed at 1, 6, 12, 24, 36, 48, and 60 months. Subject evaluation at 1 month will include a Complete Physical Exam, Labs (BUN and Creatinine), and a Thoracic Spiral CT with and without IV contrast 2.5 mm. Subject evaluation at 6, 12, 24, 36, 48, and 60 months will include a Complete Physical Exam, Chest X-ray (AP, Lateral), Labs (BUN and Creatinine), and a Thoracic Spiral CT with and without IV contrast 2.5 mm.