A clinical trial is underway at the Hospital of the University of Pennsylvania (HUP) to study the safety and effectiveness of an endovascular medical device to treat life-threatening thoracic aortic aneurysms. Dr. Ronald Fairman, Chief of Vascular Surgery at HUP, is leading the study, one of 35 principal investigators in North America to participate in this landmark trial.
The clinical trial, called STARZ-TX2 (Study of Thoracic Aortic Aneurysm Repair with the Zenith TX2 Thoracic TAA Endovascular Graft), is open to patients diagnosed with a descending thoracic aortic aneurysm. STARZ-TX2 will compare the outcomes of patients treated with open surgery to patients treated with the Zenith TX2 Thoracic TAA Endovascular Graft, manufactured by Cook Incorporated. Specifically, the trial will assess device performance, as well as patient survival and aneurysm rupture rates in the surgical and endovascular treatment groups, over a 12-month period. The trial, which began in April 2004, will enrol 275 patients at up to 35 medical institutions in the US and Canada. Additional trial sites in Japan, Australia and Europe also will participate.
Currently, surgical repair is the standard of care for the treatment of TAAs. Surgical repair requires a surgeon to open the chest cavity, clamp off the aorta and sew a surgical graft in place to prevent an aneurysm from rupturing. Open surgical repairs carry high health risks for many older patients, who may also suffer from other significant medical conditions such as heart disease, lung disease, diabetes or hypertension.
The Zenith TX2 system requires an incision to insert the graft's hydrophilic, kink-resistant delivery system into the femoral artery in the leg. Once the system is guided into position through the patient's arteries under fluoroscopy, a one- or two-piece, fabric-covered, self-expanding stent graft is placed inside the weakened section of the thoracic aorta to relieve pressure on the aneurysm, helping to reduce the risk of rupture.
The system is a reinforced fabric tube that is sized to the length of the aorta that needs to be covered to seal off the aneurysm. The graft itself is made of a polyester material like that used in open surgical repair. Standard surgical suture is used to sew the graft material to a frame of self-expanding stainless steel stents, which provide support.
Patients treated with endovascular devices such as the Zenith aortic graft typically experience less trauma and a much shorter recovery period compared to patients undergoing open surgical procedures. Patients enrolled in the STARZ-TX2 trial have been diagnosed with aneurysms of the descending thoracic aorta. To be eligible for the study they must be a candidate for either surgery or endovascular repair and at least 18 years old. To receive treatment in the STARZ-TX2 trial, patients must meet specific requirements regarding the type and size of aortic aneurysm in the descending aorta (other medical inclusion and exclusion criteria may also apply).
While the Zenith TX2 is not currently approved for commercial use in the US, it is used in Asia, Australia and Canada. Several thousand patients have been treated outside the US for the past six years with the Zenith TX2 Thoracic TAA Endovascular Graft. The Zenith TX2 system is already approved for commercial distribution in Canada, Australia and Asia, but is an investigational device not yet available for sale in the US. In January COOK launched Zenith TX2 in Europe, which replaces the TX1 device. COOK also announced the implant of the Zenith TX2 Endovascular Graft at the International Symposium on Endovascular Therapy (ISET) 2005, where physicians from Canada successfully carried out the procedure during a televised event.
Drs. Bao Bui and Andrew Benko, interventional radiologists, and Dr. Bertrand Scalabrini, vascular surgeon, from Centre Universitaire de Sante de Sherbrooke, completed the endovascular procedure in less than an hour on an elderly male patient during the live event, which was broadcast to more than 1,000 radiologists at ISET.
"The Zenith TX2 is a very reliable device and its deployment is very predictable as compared to other devices," said Dr. Bui, who has implanted more than 40 Zenith TX2 devices in patients in Canada, where the device is available for use. "This means we can place the device precisely with ease."
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