Biomedical subjects
Publications and source records attributed to D L Ballantyne.
The stereomicroscopic appearance of the vasculature and circulation of groin flaps, with their epigastric pedicles divided at various time intervals, is an early diagnostic indication of flap viability. A simple and comprehensive training model, with characteristic vascular and flow changes within a single flap, is provided in rats, with pedicles transected at three to four days after the flap is raised.
A lacerated fresh leaf is introduced as a model for developing and refining microvascular skills. Being friable, this plant tissue exaggerates damage due to technical errors, therefore improving a trainee's skills.
This study entailed direct stereomicroscopic observations of rat abdominal island flaps and the sequence of vascular events that occurred during and after occlusion by clamping of the individual femoral vessels for varying time intervals of up to 16 hours. The vascular changes and the status of the circulation in the flap vasculature, including the timing of complete hemal stasis and resumption of flow, following the application and subsequent release of the vessel clamp were observed and correlated with flap viability and behavior. This study also included a grading system of the vascular changes observed under a stereomicroscope. From these findings, it is suggested that in vivo stereomicroscopy may serve as a new and simple clinical tool for the early diagnosis of thrombosis at the site of microvascular anastomosis of a free flap transfer and may define time limits during which the anastomosis can be successfully corrected and the flap salvaged.
An operating table stand incorporating a rotatable mechanical surface with a motorized focusing stage carrier was designed for a standard stereomicroscope. This can be used for microsurgical experiments and practicing microsurgical techniques in small laboratory animals.
Segments 15 mm in length were excised from the femoral veins of rats and preserved by refrigeration at 4 C in lactated Ringer's solution for periods up to 21 days. The findings show that veins can be preserved for up to seven days and successfully grafted to recipients. Although there was some success in preserving vein segments for more than seven days, a high rate of thrombosis occurred after implantation in the recipients. It is generally accepted that damaged endothelium causes thrombosis. The light and electron microscopic observations in this study, however, suggest that the condition of the endothelium may not be the only important factor in the patency of small vessels. A thickened and prominent elastic lamina may also play a role in keeping the lumen open.
Free groin flaps taken from rats were preserved by refrigeration at 4 degrees C in either lactated Ringers solution or tissue culture medium for various periods of time. The results indicate that a high survival rate can be expected at periods up to 72 hours, but there was no success in preserving flaps longer than 72 hours. These preliminary experimental findings suggest that, clinically, a high survival rate can be achieved in free flaps following excision from donor sites even if the microvascular transfer must be postponed for a period up to but not exceeding 48 hours.
Techniques for obtaining and implanting vein grafts in the femoral arteries of rats are described. Grafts 5 mm in length can be removed from the femoral vein without ligating any side branches; a 15-mm segment is the maximum graft that can be obtained from the femoral vein in a rat. This requires ligation and division of all the branches between the inguinal ligament and the great saphenous vein. The superficial epigastric vein also can be used as a source of grafts to be used in the femoral artery. In this study, neither the femoral nor the superficial epigastric vein appeared to have functioning valves. Therefore, reversing the vein graft before implantation was not necessary.
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From the combined procedures of skin stereomicroscopy of in situ grafts in rats, graft removal and supravital intracardiac injection of a contrast medium, the data suggest that the revascularisation of skin grafts is an orderly sequence of events which include: active invasion of the graft dermis by the ingrowing host capillary sprouts; development of anastomoses between the graft and host vasculatures; entry of blood into the graft through the vascular anastomoses by 48 hours after transplantation.
The survival of rat skin allografts was significantly increased by repeated intraperitoneal injections of 2.5 mg Valium (diazepam) into hosts. In addition, in vivo pretreatment of the donor animals at this dose level decreased the intensity of the recipients' immune responses to skin allografts. In vitro exposure of skin grafts to Valium also prolonged allograft survival.
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