Microsurgical repair after crush-avulsion injury of the femoral vein in rats: prevention of microvascular thrombosis with recombinant human tissue-type plasminogen activator (rt-PA).

Vein thrombosis is often encountered in microsurgery, especially in the case of crush-avulsion injuries. The aim of this study was to investigate the effect of systemic administration of recombinant tissue-type plasminogen activator (rt-PA) on the patency of the femoral vein of the rat, which had previously sustained a crush-avulsion injury. The study consisted of 3 groups of male Wistar rats, 20 animals each. A standardized crush-avulsion injury model was used. After microvascular repair of the femoral vein, the animals received either normal saline (group A), heparin 100 U/kg body weight (group B), or rt-PA 3.5 mg/kg body weight (group C) systemically. Patency tests were performed at 20 minutes, 48 hours, and 1 week after blood flow reestablishment. According to our results, the patency rate of the rt-PA group was significantly higher than in both the control and heparin groups.

Microvascular repair with 1-mm polytetrafluoroethylene (PTFE) grafts: effect of recombinant tissue-type plasminogen activator (rt-PA) on the patency rate and healing process.

The present study assesses the effect of recombinant tissue-type plasminogen activator (rt-PA) on the patency rate and healing process of microvascular polytetrafluoroethylene (PTFE) grafts. Wistar rats were used, divided into four groups of 25 animals each. After dissection of the carotid artery a segment of the vessel, 1 cm long, was resected and replaced by equal length graft. Two different type fibril length (30- or 60-microm) grafts of the same wall thickness (0.18 mm) were used. Normal saline or 3 mg/kg of body weight of rt-PA was applied locally in each group of different fibril length grafts. Patency tests were performed at 15 min and 4 weeks after blood flow was reestablished. All grafts were harvested and examined histologically. The results showed that local application of rt-PA improves patency statistically significantly in both types of fibril length grafts. Patency in 60-microm fibril length grafts was statistically significantly higher than that of 30-microm fibril length grafts, whether rt-PA was used or not. The use of rt-PA had no influence on the healing process of either type of graft.

Prefabrication of an axial bio-synthetic flap for circumferential tracheal defect reconstruction.

The aim of this study was to prefabricate an axial bio-synthetic flap for reconstruction of circumferential tracheal defects in a rabbit model. Two series of experiments were performed. In the first set of experiments axial island bio-synthetic flaps were prefabricated. These consisted of an inner island de-epithelialised fasciocutaneous flap from a rabbit's ear and an outer polytetrafluoroethylene vascular graft. The flaps were buried at the base of the rabbit's ear for periods of 1, 2 and 3 weeks (groups A, B and C, respectively), 10 flaps per group. Only one flap in group C failed to survive. Clinical and histological assessment, at the completion of each time period, showed that only the viable flaps of group C developed all the characteristics needed for a tracheal substitute. In the second set of experiments the prefabricated bio-synthetic flaps were transferred to the rabbit's neck by means of microvascular anastomoses. Ten such free flaps were buried at the rabbit's neck for 3 weeks (group D). Eight of the flaps remained viable and all the viable flaps had characteristics similar to those of group C. These results demonstrate the feasibility of creating a prefabricated axial bio-synthetic flap (island or free), over a 3-week period, possessing the characteristics needed for a tracheal substitute in a rabbit model.

Microvascular repair following a modified crush-avulsion injury in a rat model: effect of recombinant human tissue-type plasminogen activator on the patency rate.

The failure rate of replantations following a crush-avulsion type injury is high. This study has been designed to reproduce an effective standardized crush-avulsion injury model to the femoral artery of the rat and evaluate the antithrombotic efficacy of systemic intravenous administration of recombinant human tissue-type plasminogen activator (rt-PA). The crush-avulsion injury was reproduced by using a bulldog clamp and two hemostats and followed by microvascular repair. The animals were divided into three groups of 20 rats each and received either normal saline, heparin 100 U/kg body weight, or rt-PA 3.5 mg/kg body weight intravenously. Patency tests were performed 20 min and 48 h after blood flow reestablishment. Results showed that this experimental crush-avulsion injury model ensures low patency in the control group, whereas systemic rt-PA administration improves the patency rate statistically significantly compared to control and heparin groups at both 20 min and 48 h postrevascularization.

Combined vascular reconstruction and adjunctive tissue transfer in the treatment of infected arterial prostheses and tissue defects.

One of the most serious complications in vascular surgery is infection of the vascular arterial prosthesis (VAP) which might lead to loss of limb or even death. Very often infected prostheses are combined with infectious infiltration of the adjacent tissues or even necrosis and their loss. This paper deals with the experience in the management of 5 patients suffering from infection of vascular arterial prostheses in various locations, for by-passing abdominal aorta and distal arteries with loss or necrosis of the skin and tissues adjacent to the graft. Removal of the infected graft was performed in all of the cases, together with wide debridement of the infested area and placement of a new graft, coursing far from the infected area for revascularization of the affected limb. The cleaned infected area was covered at a first or second stage by applying plastic procedures utilizing musculocutaneous tissue transfer. The results were quite satisfactory. We conclude that the management of infected vascular arterial prostheses, when these are combined with loss of adjacent tissues, is a challenge for the Vascular Surgeon. Their removal, extended cleaning and covering of the area by means of plastic procedures with tissue transfer, proved to be effective in the management of this problem.