Evaluation of Internal Rectus Sheath Vascular Autograft for Arterial Replacement in Dogs
Dept. and Clinic of Surgery and Ophthalmology, Budapest, Hungary
The aim of the study was to work out and testify a new arterial replacement method with autograft developed from internal rectus sheath to eliminate common complications with traditional vascular replacement techniques such as thrombosis, complicated arterial reconstruction or Cyclosporine induced graft degeneration.
Examination were done on 16 experimental dogs. 32 autologous vascular grafts were developed from internal rectus sheath and were anastomosed with both sided cut ends of external iliac arteries. Dogs in group I.1. were heparinised, the individuals in II.1. were treated with Cyclosporine. Acetyl-salicylate anticoagulation therapy was administered in group I.2., which was also combined with Cyclosporine in group II.2. The follow-up period was 3 months, during which the survival and function of vascular grafts were checked regularly by physical examination as well as doppler ultrasonography. After the follow-up period thorough macroscopic and microscopic histopathology were carried out. ANOVA test was used for statistical analysis.
There was no technical difficulty during either the development or the anastomosis between the grafts. Perioperative complication was not experienced either. In the postoperative period the physical and the doppler ultrasonographic examination revealed well correlated results. In group I.1., I.2. and II.1. 2 of each suffered from either obturation by thrombotisation (I.1.) or stenosis at proximal anastomosis (I.2., II.1.). Grafts remained patent and functioned at median 370 cm/sec flow rate detected and measured by doppler. All grafts of group II.2. remained patent with an average 383 cm/sec arterial flow rate. Macroscopic and histopathological evaluation of graft quality 3 months after implantation revealed that the patent grafts pulsated normally showing an average 1,5 mm widening of the lumen during reoperation. The mesothelial layer originated from the rectus sheath was detected in spots by histopathology. Certain transformation process was dominant characterised by proendothelial monolayer development from the site of anastomoses covering mostly the entire inner surface of the graft. Elastic fibers as well as smooth muscle structures were found within the wall of the grafts via histology indicating angiogenetic processes. Fibrin and small vessel structures were also detected with fibrin-collagen staining. The positive result of the von Willebrandt staining proved the appearance of proendothelial monolayer via immunohistochemistry. The electromicroscopic examination confirmed the presence of intact fibrin és elastic fibers as well as actin and well structured mitochondria as evidence of proper tissue oxygenisation. Cyclosporine was not proved as having degenerative effect on the rectus sheath graft.
The study has proven that arterial autografts developed from internal rectus sheath are able to survive and function as vascular conduit used in human as well as in veterinary surgery.
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