Without treatment, between 60 and 70 percent die within a week, according to published figures. A dissection can occur either in the ascending aorta, which is contiguous to the heart and directs blood supply to the head and arms, or in the descending aorta, which carries blood into the abdomen and pelvis. A tear in the ascending aorta, known as a Type A dissection, is typically treated with a surgical procedure in which a tube of polyester graft material is stitched to the arterial wall to replace the damaged segment. The mortality rate among patients who undergo this surgical repair is about 10 to 15 percent in medical centers with special expertise and extensive experience in thoracic aortic surgery, such as Stanford, Miller said. Patients who have a rip in the descending aorta, known as a Type B dissection, are most often treated with drugs to keep their blood pressure in check.
More complex cases require surgery.
Still, about 20 percent of these patients die as a result of complications, Dake said. The researchers began testing the stent-grafts for descending aortic dissections in 1996 as a possible alternative to traditional open surgery and in hopes of improving patient odds of survival. During the dissection procedure, the stent-graft is collapsed inside a catheter, which is threaded from the patient's groin to the area of damage in the aorta. Once in place, the stent-graft is released as the catheter is withdrawn. The device then expands to fill the vessel, effectively covering the hole and restoring blood flow.