人工血管の最近の諸問題

抄録

The choice of synthetic vascular prostheses for arterial reconstuction surgery should be based on the data evaluated in long term both experimentally and clinically.
Stable and viable inner capsule for a period of long time leads implanted graft to maintain the desirable function as a substitute for blood vessel.
In order to clarify the healing mechanism of implanted vascular prostheses, following pathology should be analized. 1) Healing process from the sites of anastomoses. 2) Dissemination of multipotential blood cells on inner capsule and 3) The influence of capillaries of intercapsular space between meshes.
Healing process from the host artery is not simple extension of endothelial cells to inner capsule, but is the result of healing motion from exaggerated porosity at the sites of anastomoses. And this phenomenon is possibly influenced by the blood flow according to our observation scale of endothelial cell-encapsulation density.
Dissemination of multipotential cells in flowing blood on inner capsule seems to be quite acceptable to get new endothelialized cell lining Further studies will reveal whether the origin of endothelial cells is from blood stream or development of cells from the sites of anastomoses.
In regard to the intercapsular capillary communication, there are out-growing capillaries of vasa vasorum which are found on the specimen of 83rd postoperative day in the earliest, mostly near anastomotic lines. These openings were found under the scanning electron microscopic study and they were confirmed as vasa vasorum by microscopic examination of serial section.
The ideal stable structure of inner and outer capsules is that the viable collagen fibers with in- and out-growing capillaries are filled in wide space between meshes.
Very thin inner capsule and viable intercapsular structure are seen specifically in the use of high porous grafts.
Specifications for vascular prostheses, such as knitted finly, thin-walled, soft, pliable, high porosity, efficient preclotting, comformability at anastomotic lines and no fraying when cut at any angle are fullfilled by the Weavenit, Milliknit and Microknit vascular prostheses.
Indications for arterial reconstruction surgery became broad by using the high porous grafts; bypass graftings beyond inguinal ligament and knee crease and possibility for the clinical use of small caliber grafts for A-V shunt in hemodialysis and for coronary bypass operation.