The invention will be discussed generally with respect to deployment of a stent graft into the thoracic aorta but is not so limited and may apply to deployment into other body lumens.
It is important when delivering a stent graft by intraluminal or endovascular methods to know exactly where the device is in the vasculature particularly in relation to branch vessels which could be adversely occluded by placement of the stent graft. To avoid occlusion there have been proposed fenestrations along the length of a stent graft and scalloping at the proximal and distal ends of the stent graft to allow flow from a main vessel to a branch vessel through the fenestration or scallop.
The use of radiopaque markers around the periphery of the fenestration or scallop in this regard has been proposed but it would be advantageous if a more certain or reliable method could be devised to assist with placement.
Particularly when deploying into a curved vessel it is known that a deployment device will take up a position in the vessel on the outside or greater radius side of the curved vessel and hence if a stent graft could be retained onto a deployment device so that a fenestration or scallop on the stent graft is in a selected position with respect to a portion of the deployment device when it is curved then more accurate positioning may be possible.
As a particular example, the aorta of a patient comprises an ascending aorta from the aortic heart valve, a thoracic arch and a descending aorta. Major branch vessels extend from the thoracic arch and occlusion of one or more of these upon placement of a stent graft in the thoracic arch could have serious consequences. The major vessels generally extend from the outside or greater radius side of the curved thoracic arch and so if a was stent graft retained onto a deployment device such that a scallop on the stent graft was on the outside of the deployment device when it is curved then correct placement would be surer.
It is known to retain the proximal and distal ends of a stent graft onto a deployment device to facilitate relative longitudinal and rotational movement of the ends but owing to tortuosity of vessels through which a deployment device must be progressed and the rotation necessity to achieve progression the final rotational position of a stent graft may not be fully known.
It is an object of this invention to provide a retention mechanism for a stent graft onto a deployment device for more accurate deployment of the stent graft therefrom or to at least provide a practitioner with a useful alternative.
Throughout this specification the term distal with respect to a portion of the aorta, a deployment device or a stent graft is intended to mean the portion of the aorta, deployment device or stent graft further away in the direction of blood flow away from the heart and the term proximal is intended to mean the portion of the aorta, deployment device or end of the stent graft nearer to the heart. When applied to other vessels similar terms such as caudal and cranial should be understood.