Impermeability to blood of the E-vita open plus hybrid stent-graft: experimental and clinical evaluation

To evaluate the impermeability to blood of the modified E-vita open plus hybrid stent-graft in animal experiments and initial clinical applications in the replacement of the ascending aorta and aortic arch combined with antegrade stent-grafting of the descending aorta.

In 3 acute pig experiments, a tightly woven hybrid stent-graft (18 x 50-mm) was implanted in the descending aorta. Blood loss was measured after clamp release in fully heparinized animals by wrapping the aortic segment in a polyethylene bag. For histological examination, 12-mm-diameter stent-grafts were interposed in the abdominal aorta of 6 minipigs. The animals were sacrificed and studied after 3, 6, and 9 weeks. Between October 2008 and October 2009, 9 patients were treated for 6 type I dissections and 3 thoracic aortic aneurysms using the new prosthesis. Blood loss and blood replacement were evaluated.

Mean blood loss under heparinization was 35+/-4 mL/min in the animal model. Histological examination of the explanted grafts demonstrated buildup of neointima. In the clinical cases, the mean blood loss within the first 24 hours was 489 mL; no re-exploration for bleeding was required. During a 6-month follow-up, no thrombus formation was seen within the vascular graft and no embolic event occurred.

The new low-porosity hybrid prosthesis proved to be absolutely tight in animal experiments; histological examination demonstrated endothelial cell ingrowth with a trend to hyperplasia in this small-diameter graft. These results were confirmed in the clinical cases by the extremely minimal blood loss and an uneventful course.