Evaluierung eines Neurostent-Prototyps am experimentellen Aneurysma-Modell

The occurrence of a subarachnoid hemorrhage (SAH) is a
life-threatening disease, which is accompanied with a very high
rate of morbidity and mortality. The main cause of a non-traumatic
SAH is a ruptured cerebral artery aneurysm, which primarily leads
to a bleeding into the arachnoid cisterns of the brain. In spite of
this positive trend in the area of new endovascular materials and
techniques, certain intracranial aneurysms still prevent the
application of this minimal invasive therapy. A first promising
approach to this problem lies in the application of a vascular
stent in combination with a platinum coil to allow a permanent
occlusion of the broad-based aneurysms. With the use of these
stents a more sealing embolization, a faster and better thrombosis
of the aneurysm as well as a modulation of the blood flow in the
parent vessel should be achieved. This thesis examines the
application of an electrolytically detachable and completely
repositionable stent prototype as a therapy for broad-based
intracranial aneurysms by the utilisation of an elastase-induced
aneurysm model in 12 rabbits. For the evaluation of this novel
system the stent was implanted and the aneurysm was subsequent
embolized with conventional coils. A final examination after three
month was accomplished by the use of MRT, CT, DSA and histology.
The stent presented itself as a flexible and easy to navigate
implant. In every case the positioning and repositioning was
possible without any complications. During the intervention and all
along the examination time its radial forces lead to an adequate
vascular adaptation without any deformation of the vessel. The
functional mesh-design allowed a flawless probing of the aneurysms
with the micro-catheter. The stent served as a bearing for the
coil-package and prevented a protrusion. The three imaging methods
allowed an evaluation of the interesting parameters: In 11 of 12
cases the aneurysms showed a very good occlusion, in all cases the
long-term patency of the stent was present and finally no
recanalisation occurred. The stent fulfilled the requirement of
being highly bio-compatible. However, regarding the material,
difficulties in form of stent breakage and in association with the
detaching mechanism emerged. Only with 2 animals the number of
detaching attempts satisfied the expectations. If the recovered
shortcomings will be eliminated, the acquired data and results
within this thesis are promising an efficient and effective
application of the prototype for the therapy of broad-based
aneurysms. Despite the restrictions regarding the transferability
of data gathered by animal experiments to the intracranial, human
situation, the obtained results could be the basis for a clinical
adoption of this novel stent system in human patients.