Throughout this specification when referring to deployment of a stent graft or prosthesis within the aorta of a patient the term proximal will be used for that end of both the deployment device and the stent graft at that end which is closer to the heart of a patient and the term distal will be used for that end of the deployment device or stent graft which in use is furthest from the heart. When applied to other vessels corresponding terms such as caudal and cranial should be understood.
Deployment of stent grafts within the thoracic aorta using an endovascular deployment method through the iliac arteries into the aorta can be done with a deployment device which has retained on it a stent graft which includes an exposed stent at the distal end of the graft.
As the stent graft has in one embodiment an exposed stent at the distal end preferably with barbs on it, it must be deployed in a device which keeps the barbs covered until deployment is required. This can be done with a capsule, which covers the exposed stent, but there is a problem. When withdrawing the capsule, a proximal end retention system, which uses trigger wires to retain the proximal end of the stent, can be released by pulling the trigger wires, thereby releasing part of the graft prematurely.
It is the object of this invention to provide a deployment device which overcomes this problem or at least provides the physician with a useful alternative device.