This invention will be discussed in general with respect to aortic aneurysms and the use of an implantable device such as a stent graft to bridge an aneurysm and in particular in the descending aorta, but the invention is not so limited and may be used for any region of the human or animal body and any type of implantable device.
An aortic aneurysm can be abdominal (occurring in the abdomen) or thoracoabdominal (a single aneurysm occurring partially in the thorax and partially in the abdomen). Abdominal aortic aneurysms are sometimes referred to as “AAA”; while thoracoabdominal aortic aneurysms are sometimes referred to as “TAAA”. A stent graft can be used to bridge an aortic aneurysm, but where there are side branch arteries from the aorta it may be desirable to have side branches extending from the stent graft to give a blood supply to as many side branch arteries as possible.
After an endovascular operation to place a stent graft into the descending aorta, the human or animal body can in time adapt to lack of blood supply from some arteries which are excluded by the stent graft. For instance, blood supply via the intercostal arteries to the spinal cord can be alternatively achieved via other arteries, such as for instance the celiac artery, the superior mesenteric artery, lumbar and internal iliac arteries.
There can be a problem, however, of blood supply immediately after an operation, at least in part relating to blood pressure. Furthermore, patients with thoracoabdominal aortic aneurysms may have upward-facing renal arteries. It may be difficult to cannulate an upward-facing renal artery, as tracking a stiff bridging stent out of the branch and into the artery may pull the wire out of the branch.