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Home > Press Center > Press Releases from 2005 Annual Meeting > Pressure sensor proves useful in endovascular aneurysm repair

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Jill Goodwin
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An implantable sensor that monitors blood pressure in an aneurysm sac has proved to be safe and useful in guiding endovascular repair of the aneurysm, according to research presented at the annual meeting of the Society for Vascular Surgery in Chicago. Now that the EndoSensor has proven feasible in an international clinical trial, investigators are assessing whether it will become a safer alternative to contrast CT scanning for long-term monitoring of the aneurysm repair site.

As many as 2 percent of endovascular repairs of abdominal aortic aneurysms (AAA) that are successful in the first year after the procedure fail every year thereafter. This late aneurysm rupture, which can be fatal, might be prevented if surgeons could more accurately detect and treat residual leaks around the stent graft during the procedure and in the immediate postoperative period. Currently, surgeons use contrast CT both during and after the procedure to monitor such leaks, but the technique is not foolproof. Moreover, repeated exposure to the contrast material can impair the patient’s renal function.

The EndoSensor (CardioMEMS, Inc., Atlanta) was devised to be implanted at the time of endovascular AAA repair. It measures pulse pressure within the aneurysm sac. The device was tested against standard monitoring methods in a prospective clinical trial involving 70 patients treated at 9 U.S. and 3 overseas medical centers. The EndoSensor was successfully implanted and relayed accurate pressure readings in 65 (93 percent) of them. It accurately detected endoleaks, signaled by a 30 percent or more drop in pulse pressure, in all 15 patients who developed them during the surgery. “These results show that intrasac pressure sensing can be used as an adjunct to angiography during endovascular aneurysm repair to diagnose the location and type of endoleaks,” said Dr. Takao Ohki of Montefiore Medical Center, New York.

“Additional studies are in progress to demonstrate pressure sensing as an alternative to CT for the long-term monitoring of sac stability,” he added. The EndoSensor is limited to investigational use only.

The aorta is the largest artery in the body and carries blood away from the heart. The abdominal aorta is the portion of that artery that runs through the abdomen and supplies blood to the lower body. When a weak area of the artery expands or bulges, it is called an abdominal aortic aneurysm. A normal aorta is about 1 inch in diameter, but an aneurysm can stretch the artery much wider and can even make it burst, causing internal bleeding that is often fatal. Approximately 200,000 cases of AAA are diagnosed every year in the United States, and nearly 15,000 of these are considered at risk of rupturing. In an endovascular (within the vessel) aneurysm repair, the procedure is performed inside the body by using long, thin tubes called catheters that are threaded through the blood vessels. This approach requires only a small incision in the groin area where the catheters are inserted, rather than the large abdominal incision that is required for an “open” surgical repair. During the endovascular procedure, the surgeon uses live x-ray films displayed on a video screen to guide an endovascular stent graft to the site of the aneurysm and to deploy it there. The stent graft is a fabric and metal tube the size and shape of a healthy aorta, which strengthens the walls of the aorta and allows blood to pass through it. “Endoleaks” are areas of leakage around the outside of this stent graft, which can build up over time and cause the aneurysm to enlarge and eventually rupture.