Streptokinase in the management of limb arterial thrombosis following free-flap surgery

Intraarterial streptokinase was used in the treatment of leg vessel thrombosis following free-flap closure of a large, open wound. Attention is focused on the coagulation anomalies present in such cases and the successful use of local thrombolytic therapy to salvage the limb.     

Application of the cross-bridge microvascular anastomosis when no recipient vessels are available for anastomosis: 85 cases

The purpose of this article is to introduce the results of free tissue transfers using the technique of the cross-bridge microvascular anastomosis when the recipient lacks suitable vessels for anastomosis. Between May of 1982 and June of 2002, a series of 85 patients underwent this procedure. The transferred tissues were the free latissimus dorsi myocutaneous flap, the free vascularized fibula, the free fibular osteocutaneous flap, and the free iliac osteocutaneous flap, alone or in combination. The donor vessels were the anterior tibial artery and great saphenous vein, the posterior tibial artery and its venae comitantes, and the radial artery and cephalic vein. Good results were achieved. The success rate reached 95.29 percent. The authors believe this procedure can be performed in the event of serious tissue defect where the vessels are unsuitable for anastomosis.     

Temporary assisting suspension suture technique for successful microvascular anastomosis of extremely small and thin walled vessels for mice transplantation surgery

Dissection and microsurgical anastomosis in small and thin-walled vessels is challenging. Temporary assisting suspension suture technique was developed to overcome those difficulties in establishing successful composite tissue allotransplantation in mice. The operations were performed in 12- to 16-week-old Balb/c mice weighing 25 to 30 grams as both donor and recipient animals. Extended vascularized groin cutaneous flaps based on the superficial epigastric vessels were used. A total of 10 groin cutaneous flaps were transplanted. Three temporary assisting suspension sutures of 11-0 nylon were placed at the 12-, 4-, and 8-o'clock positions to donor and recipient artery and vein before the anastomosis. This technique allowed atraumatic dissection of delicate and thin vessels, prevented vessel wall collapse, and facilitated adequate exposure of the lumen during placement of the permanent microvascular sutures. Thus, the microvascular anastomosis was performed in an unusual manner. The temporary assisting suspension sutures were removed just before the permanent suture was tied down. The mean operation time was 1 hour and 45 minutes with an ischemia time of 1 hour. Ninety-percent success in immediate and late-term patency rates was achieved, which was confirmed by transplant survival. This technique was proven to be useful for microvascular anastomosis in thin-walled vessels and is recommended.     

Therapeutic value of intravenous heparin in microvascular surgery: an experimental vascular thrombosis study

In an attempt to decrease a 10 to 15 percent vascular thrombosis rate leading to graft occlusion, low-dose human-grade heparin was studied to determine if carefully monitored intravenous therapy would increase 7-day patency in a known potent thrombosis model. In New Zealand white rabbits, the type of infusate administered intravenously, either saline (30 animals) or heparin (35 animals), was selected at random after completing a 2-mm arterial inversion graft in the femoral artery. A 72-hour infusion was used in all animals; the control group received sterile saline and the experimental group received a heparin infusion at 45 microliters per hour after a 500-unit bolus. All grafts in both groups were patent at the time of groin closure. Patency in the heparin-perfused group was 67 percent (24 of 35) as compared to 19 percent (6 of 30) in the control group (p less than 0.05) 1 week postoperatively. Scanning electron microscopy showed significantly less dense fibrin deposition and a decrease in the number of aggregated platelets in the heparin-perfused grafts. Partial tissue thromboplastin time values in the experimental group ranged between 55 and 75 seconds (control 20 to 25 seconds). We have shown that heparin, an inexpensive and readily available agent, maintains 1-week microarterial patency and results in few complications in a reliable, reproducible, and versatile thrombosis model. The clinical ramifications of using an antiplatelet agent that diminishes fibrin deposition in microsurgery are apparent.     

An absorbable catheter system for use in microvascular and peripheral vascular surgery: an experimental study in the canine.

An absorbable catheter for use in regional anticoagulation in microvascular and peripheral vascular surgery was studied in 20 sites in 10 adult beagle dogs to answer three questions: (1) Could the polyglycolic acid and trimethylene carbonate catheter withstand intraarterial pressures of infusion and completely absorb over a predictable time interval? (2) Could the catheter be filled with heparin and maintain patency for reuse after a 24-hour interval? (3) Could the catheter be placed in a side branch of a major artery and, after catheter dissolution, maintain long-term patency of the primary feeding artery? The catheters were completely absorbed from 24 to 34 weeks following implantation. The catheters were able to withstand intraarterial pressures, and no evidence of significant thrombosis of the primary feeding artery was seen in any animal studied. No complications of catheter leak, hematoma formation within the catheter placement sites, or sepsis were noted in any of the 20 catheter sites studied.     

Histologic results of neuronal anastomosis of the microvascular latissimus dorsi transplant

Latissimus dorsi transplants have little neuronal regenerative capacity without neuronal anastomosis. Histologic differences between transplants with and without neuronal anastomosis and two distinct types of neurotization are highlighted in this study. Eighteen patients after tumor resection and defect coverage with a latissimus dorsi transplant were examined preoperatively and postoperatively by means of a biopsy for histologic examination. The number of fascicles, degree of scarring, myelinization, and fibrosis were examined. All patients had a mean of 11.8 fascicles preoperatively. Patients without neuronal anastomosis showed an average of 5.0 fascicles, patients with nerve anastomosis to the cutaneous branches of the intercostal nerve showed an average of 6.2 fascicles, and patients with anastomosis to the thoracodorsalis nerve showed an average of 9.2 fascicles postoperatively. In cases of nerve anastomosis, a lesser degree of fibrosis was found, together with good myelinization. Neuronal reanastomosis led to more vital neuronal structures in the postoperative histologic specimen. The highest density of fascicles was found in the case of the well-vascularized thoracodorsalis nerve.     

Importance of additional microvascular anastomosis in esophageal reconstruction after salvage esophagectomy

Esophageal reconstruction after salvage esophagectomy in patients who have undergone curative-intent chemoradiotherapy for esophageal cancer is associated with a significant risk of perioperative morbidity and mortality. In particular, anastomotic leakage can cause severe and potentially fatal complications, including mediastinitis and pneumonia. The authors performed esophageal reconstruction with a pedicled right colon graft after salvage esophagectomy in eight patients. To decrease the rate of anastomotic leakage, the authors performed an additional microvascular anastomosis at the distal end of the graft. The distal stumps of the ileocolic artery and vein were anastomosed to the cervical vessels. After surgery, aspiration pneumonia and localized wound infection were observed in two patients each, but slight anastomotic leakage was observed in only one patient. Postoperative swallowing function was satisfactory in all patients. Although the incidence of anastomotic leakage is reportedly high, the authors observed anastomotic leakage in only one of eight patients. The authors believe that additional microvascular anastomosis helps prevent anastomotic leakage, especially in patients who have undergone salvage esophagectomy after curative chemoradiotherapy.     

Use of human amnion for microvascular interpositional grafts

A major problem associated with vascular grafting employing an artificial graft is the inflammatory response provoked by the graft and subsequent complications of classical acute rejection phenomena when the graft is implanted subcutaneously into human volunteers. The favorable results obtained by a preliminary study of subcutaneous implantation of amnion in our laboratory have led us to a prospective study to determine its value as a vascular graft. Tubed conduits of glutaraldehyde-treated amnion were hand constructed of varying diameters and lengths. They were employed as segmental interpositional grafts in experimentally created femoral and aortic arterial defects in Sprague-Dawley rats. Patency rates varied from 60 to 90 percent, with all grafts showing remarkable reendothelialization within 3 to 4 weeks postoperatively. Morphology, antigenic reaction, blood flow, and patency of the different experimental amnion grafts were evaluated and compared to appropriate controls.     

Use of the united suture in microvascular anastomoses.

A technique for microvascular anastomoses is described. It leaves one suture united until the last, a maneuver which helps to avoid picking up the posterior wall with the anterior wall.     

Reactive thrombocytosis alone does not affect the patency of microvascular anastomosis in the splenectomy rat

Vascular thrombosis is a harbinger of failure in microsurgery. However, there is still controversy regarding the correlation of the complications of thrombocytosis and thrombosis. Some evidence indicates that patients with elevated platelet counts tend to have a higher flap failure rate, and surgeons usually hesitate to operate on patients with thrombocytosis. Nevertheless, the authors have experienced successful free tissue transfer in seven patients with thrombocytosis resulting from traumatic splenectomy or multiple trauma. On the basis of clinical observation, the authors investigated whether reactive thrombocytosis contributes to the patency of a microvascular anastomosis. In a rodent splenectomy-induced thrombocytosis model (n = 40), stable reactive thrombocytosis occurred after postoperative days 5 to 10, with the peak on postoperative day 7. Femoral artery division and reanastomosis was performed in rats with or without splenectomy-induced thrombocytosis, and vascular patency was assessed. Platelet counts and platelet activation were studied in correlation to microvascular patency. Platelet activation as demonstrated by CD62P expression on platelets was not significantly different between rats with and without thrombocytosis (6.41 +/- 0.95 percent versus 4.51 +/- 0.55 percent, respectively; p = 0.089). As immature platelets were not increased (2.86 +/- 0.33 percent versus 1.99 +/- 0.32 percent, p = 0.074), it seems that the splenectomy-induced thrombocytosis is the result of redistribution of platelets instead of an increase in bone marrow production. There were no significant differences in the patency rates or perfusion units of femoral artery after arterial anastomosis between rats with and without thrombocytosis (90 percent and 95 percent, respectively; p = 0.561). In conclusion, this study demonstrates that microvascular anastomosis can be performed safely in patients with reactive thrombocytosis without platelet activation.     

In vitro evaluation for potential calcification of biomaterials used for staple line reinforcement in lung surgery

Bovine pericardium (BPC) and polytetrafluoroethylene (PTFE) have been widely used to reinforce staple lines in lung resection. Since limited information regarding the calcification of these biomaterials is available, we undertook an in vitro study to evaluate their calcification potential. Commercially available BPC and PTFE biomaterials were evaluated and compared with custom-prepared BPC tissue. In vitro calcification was performed via submersion in supersaturated solution in a double-walled glass reactor at 37.0 degrees C +/- 0.1 degrees C, pH 7.4 +/- 0.1, mimicking most ion concentrations of human blood plasma. In processing of calcification, the pH decrease of the solution simulated the addition of consumed H(+), Ca(2+), and PO(4)(3-) ions from titrant solutions, the concentrations of which were based on the stoichiometry of octacalcium phosphate. The molar ion addition with time was recorded, and the initial slope of the curve was computed for each experiment. The rate of calcification developed (molar calcium phosphate ion addition rate per time and total surface area) (R) was computed after that with respect to the relative supersaturation (sigma) used in each experiment. R for custom-prepared BPC tissues was found to be in the range of 0.19 +/- 0.08 to 0.52 +/- 0.19 (n = 17) in sigma range of 0.72 to 1.42. Commercial BPC was found to be 0.016 to 0.052 (n = 4), and PTFE was 0.005 to 0.05 (n = 8) in the same sigma range. Both clinically applied biomaterials, BPC and PTFE, seemed to be calcified with rates of at least one order of magnitude lower than the custom-prepared BPC tissue. This data suggested that BPC and PTFE biomaterials showed a similar, relatively very low tendency for calcification compared with custom-prepared BPC tissue. Although further studies are necessary, staple line reinforcement by these two biomaterials should be considered safe from the calcification point of view.     

A novel vascular clip design for the reliable induction of 2-kidney, 1-clip hypertension in the rat

The 2-kidney, 1-clip (2K1C) model has provided many insights into the pathogenesis of renovascular hypertension. However, studies using the 2K1C model often report low success rates of hypertension, with typical success rates of just 40-60%. We hypothesized that these low success rates are due to fundamental design flaws in the clips traditionally used in 2K1C models. Specifically, the gap widths of traditional silver clips may not be maintained during investigator handling and these clips may also be easily dislodged from the renal artery following placement. Therefore, we designed and tested a novel vascular clip possessing design features to maintain both gap width and position around the renal artery. In this initial study, application of these new clips to the left renal artery produced reliable and consistent levels of hypertension in rats. Nine-day application of clips with gap widths of 0.27, 0.25, and 0.23 mm elicited higher mean arterial blood pressures of 112 ± 4, 121 ± 6, and 135 ± 7 mmHg, respectively (n = 8 for each group), than those of sham-operated controls (95 ± 2 mmHg, n = 8). Moreover, 8 out of 8 rats in each of the 0.23 and 0.25 mm 2K1C groups were hypertensive, whereas 7 out of 8 rats in the 0.27 mm 2K1C group were hypertensive. Plasma renin concentrations were also increased in all 2K1C groups compared with sham-operated controls. In summary, this novel clip design may help eliminate the large degree of unreliability commonly encountered with the 2K1C model.