To assist beginners in the microsurgical practices of handling instruments and tying knots before using an animal model, the authors suggest the use of colored beads. These beads will diminish eyestrain and secondary fatigue. Also, working with colored beads might be a little more amusing and enjoyable for beginners in learning microsurgical techniques during preliminary studies to achieve the necessary orientation for working under the operating microscope.

The superiorly based bilobed flap should be always kept in mind when planning a local flap in the infraorbital region.

Clinical attempts are made to avoid rotating a flap and twisting the pedicle for fear of perfusion compromise. Torsion of an island rat groin flap pedicle is not a well-recognized experimental entity. The authors describe the results of island flap rotation with pedicle twisting in the rat groin flap model. Forty male Wistar rats were randomly divided into four groups of 10 animals each. In each group, bilateral groin flaps were elevated; one flap was sutured in place without rotation and the contralateral flap was subjected to 180, 270, 360, or 720 degrees of rotation. Blood flow within the flaps was assessed by laser Doppler flowmetry, and flap edema and necrosis were determined 10 days postoperatively. No differences were noted between control flaps and those subjected to 180 and 270 degrees of rotation. Although flaps subjected to 360 degrees of rotation demonstrated a large amount of postoperative edema and congestion of the subcutaneous tissue with some histologic changes, all flaps in this group survived. Measured flap weights at death were different from those of controls. All flaps subjected to 720 degrees of rotation underwent ischemic necrosis. Because of the differences between human skin architecture and rat skin architecture it cannot be concluded that similar results would be observed in any human skin flap. There might be three important points arising from this study of unknowingly twisted island groin flap pedicles in the rat model: (1) twisting of less than 360 degrees has no effect on flap survival; (2) twisting of 720 degrees is always associated with skin flap necrosis; (3) twisting of 360 degrees, although associated with some changes, does not cause skin flap necrosis.

An experimental study was done in a rat groin flap model to assess the possible effects of arteriovenous fistulas (AVF) on the viability of skin flaps. The animals were randomly divided into three groups. In Group 1, an island flap, and in Groups 2 and 3, peninsular flaps, including the superficial epigastric artery and vein, were elevated. In Group 2, the base of the peninsula was on the rectus side of the flap; in Group 3, the base of the peninsula was located on the lower extremity side. After elevation of the flap and following arteriovenotomy, an A-V fistula was produced by side-to-side anastomosis proximal to the pedicle at the level of the common femoral vessels. Then the flaps were sutured back into their beds. All the island groin flaps with the AVF failed to survive. In Group 3, there was a severe reduction of blood flow in the flap and no flaps survived; however, all the flaps in Group 2 survived totally with no problem. It was concluded that island skin flap circulation is negatively affected by an AVF proximal to the flap pedicle. If the flap and AVF are treated as in Group 2, then flap necrosis caused by reduced blood flow can be overcome in this model.

No abstract

The authors describe a study in which groin flaps from 20 Wistar rats were transplanted to another group of 20 Wistar rats and, after various time intervals, the groin flaps were re-transplanted back to the original animals. The goal of the first transfers was to preserve the flap in the second group of animals (isopreservation). During the isopreservation period, the second rat (the preserver) was treated with steroids or FK506 for immunosuppression. Thirty-three free groin flap transfers were performed between 40 rats. If possible, the same flap was transferred twice between two animals, one as an isograft, and other as an autograft following an isopreservation period in 13 pairs of animals. (A second transfer was not possible in seven pairs of animals.) The period for isopreservation varied between 2 days and 1 week. The survival of the flap was observed by visual inspection, laser Doppler flowmeter measurements, and was correlated with serial histopathologic examinations of skin and vessel biopsy specimens, including the anastomosis site. The severity of histopathologic signs that might be related to developing rejection was increased by the preservation time, and was more noticeable after the second transfer. The authors showed that successful secondary transplantation of the rat groin flap with a 1-week follow-up could be achieved, following isopreservation of at least up to 5 days.

This study was undertaken to evaluate the application of autogenous fascia as a framework for a fibrocollagen tube for small-caliber vascular prostheses in Japanese white rabbits (n = 15). The fascia, measuring 10 x 40 mm, was harvested from the dorsal fascia and was carefully wrapped around a silicone rod of 1.5 mm in diameter. Then, the fascia-wrapped silicone rod was implanted into a subcutaneous pocket on the medial thigh. Four weeks later, the fascia-wrapped silicone rod was removed from the subcutaneous pocket. The rod was removed from the material, and the fascia-wrapped fibrocollagen tube was treated to make it antithrombogenic. Subsequently, the 1.5 x 10-mm fascia-wrapped tube was prepared as an arterial conduit. Using microvascular techniques, the tube was interposed into the divided femoral artery. Eleven of 15 grafts maintained patency over the follow-up period and no aneurysmal formation was found at any graft site. Microscopically, there was an ingrowth of endothelium with fibroblast proliferation from each end of the recipient vessel at 2 weeks after interposition; however, no neointima was found to line the center of the conduit. At 5 weeks after interposition, the neointimal growth rate was 70 percent. There was an ingrowth of endothelium with fibroblast proliferation from each end onto the entire internal surface of the conduit at 8 weeks after interposition. Further study is required before any long-term conclusions can be drawn.

No abstract