Biliary tract reconstruction using an autologous vein graft in rats

Numerous biologic and synthetic materials have been used with limited success as an interposed graft to repair segmental common bile duct (CBD) defects. The authors report here that an autologous vein graft can be successfully used to correct a CBD deficit contingent on accurate microsurgical technique immediate stenting and rapid graft vascularization. Thirty Sprague-Dawley rats underwent laparotomy and the experimental group (n=25) had a 3-mm segment of the CBD excised. The CBD defect was repaired using an interposed femoral vein graft aided by a plastic stent. The control group (n=5) had the CBD cut and repaired by means of primary anastomosis. The experimental group was subdivided into three sub-groups each examined at three different postoperative intervals: 1, 4 and 12 weeks. The results showed that inflammation was apparent in the venous wall following the first postoperative week. A progressive loss of the vascular endothelium and replacement with the columnar epithelium typical of the CBD was seen in the vein graft. Nineteen of the 25 experimental rats (76 percent) of the animals survived without complication from the surgery and there were no abnormalities in the liver biochemical tests of these animals. Any biliary tract obstruction that developed was attributed to dislocation of the stent leading to collapse of the vein graft (experimental group), or constriction of the anastomosis (control group). This study demonstrates that biliary tract reconstruction using an autologous vein graft can be successfully performed in a rat model of CBD repair. The application of this method to the clinical setting is also discussed.     

Autogenous venous graft with one-stage prepared Schwann cells as a conduit for repair of long segmental nerve defects

The use of autogenous venous graft with intraluminal injection of Schwann cells to enhance nerve regeneration of long segmental nerve defects was evaluated in a rabbit tibial nerve-repair model. Schwann cells were isolated from the excised rabbit tibial nerve by using the polylysine differential adhesion method. The cultured cells were identified by immunocytochemical labeling for S-100 protein. Tibial nerve defects in 4-cm segments were created in 24 animals, which were then divided into three groups. In Group 1, the tibial nerve defect was repaired with interposition vein graft alone; in Group 2, the nerve defect was repaired with a vein graft with intraluminal injection of Schwann-cell suspension; in Group 3, the nerve defect was repaired by autogenous nerve graft alone. At 2 months postoperatively, electrophysiologic evaluation showed that an evoked muscle action potential was recorded for the animals in Group 2, with vein grafting plus Schwann cells, and for those in Group 3, with autogenous nerve grafting, but not for those in Group 1, where vein grafting alone was used. The average motor nerve conduction velocity in the group with vein grafting and Schwann cells was 3.4 +/- 1.5 m/sec, which was slower than the nerve grafting group (7.8 +/- 1.8 m/sec). Histologic analysis confirmed there was formation of new nerve fascicles with myelination in the vein graft filled with Schwann cells. No nerve regrowth was found in the vein grafts without Schwann cells. These results suggested that isolated Schwann cells are able to survive in a vein graft, and that the vein graft with intraluminal seeded Schwann cells could be an alternative for repairing injured nerves with long gaps.     

Results of pyeloureterostomy after ureterovesical anastomosis complications in renal transplantation

OBJECTIVES: The most frequent urologic complications after renal transplantation involve the ureterovesical anastomosis (ie, leakage, stenosis, and reflux), with a frequency of 1% to 30% in different series. We present the results of pyeloureterostomy using the recipient's ureter. METHODS: From 1988 to 1996, 570 cadaveric renal grafts were performed at our institution. A Lich Gregoir ureterovesical anastomosis was used in every case. Complications involving the anastomosis occurred in 19 cases (3.3%), with 10 stenoses (1.7%), 6 cases of leakage (1.1%), and 3 of reflux (0.5%). The mean donor age was 36.2 years, and the mean duration of cold ischemia was 29.4 hours. The mean recipient age was 41.3 years. Corrective surgery was performed 0.09 years (range 0.01 to 0.22) after transplantation for leakage, 1.13 years (range 0.14 to 5.11) for stenosis, and 5.55 years (range 0.51 to 9.71) for reflux. The recipient's ureter was stented with a ureteral catheter before median laparotomy, except in 3 cases of early leakage (less than 3 days). The recipient's ureter was cut, without the need for ipsilateral nephrectomy, and sutured to the graft pelvis. A nephroureterostomia stent (Gil Vernet stent) (12 cases) or a double J ureteral stent (7 cases) was used for urinary drainage. RESULTS: One graft was lost on day 1 through renal vein thrombosis. Percutaneous nephrostomy was performed on day 2 to clear an obstruction of the double J ureteral stent in one case, and a double J ureteral stent was inserted on day 2 because the nephrouretrostomia stent was incorrectly positioned in another case. Pyelographic controls on day 15 were normal in every case. The mean follow-up was 2.25 years (range 0.24 to 6.1) (2.9 years for leakage, 2.08 years for stenosis, and 1.44 years for reflux). One patient died with a functional graft 3 years after surgery. One graft was lost 4 years after surgery through chronic rejection. There were no complications affecting the ipsilateral kidney. No further ureteral complications occurred after surgery. The mean creatinine level 3 years after surgery was 1.59 mg/dL. CONCLUSIONS: Pyeloureterostomy is a safe and permanent treatment for complications of ureterovesical anastomosis and gives excellent results. The technique requires stenting of the recipient's ureter and graft drainage with a nephroureterostomia stent or a double J ureteral stent.     

Use of free peritoneal and bladder mucosal grafts as ureteral mucosa substitutes for management of avulsion of the ureteral mucosa in a dog model

BACKGROUND AND PURPOSE: Avulsion of the ureteral mucosa is one of the most serious complications of ureteroscopy and considered challenging for urologic surgeons. In this study, we developed two novel methods to reconstruct the impaired ureter. MATERIALS AND METHODS: After ureteral mucosal avulsion in a canine model, ureteral reconstruction was performed in one of three ways: free tabularized peritoneal grafts (group A, n = 6); bladder mucosal grafts (group B, n = 6); or simple stenting technique (control group [n = 3]). At postoperative week 10, evaluation with intravenous urography (IVU) was followed by harvesting of reconstructed ureter segments for pathologic analysis. RESULTS: IVU showed nonvisualization of the collecting system of the affected side and histologic evaluation showed imperforation or stenosis in all animals in the control group. IVU showed good visualization of the reconstructed ureter without stenosis in group A and in most animals in group B. There was a mild dilation but no obvious stenosis in one animal in group B. Microscopically, all the reconstructed ureteral lumens were uniformly lined with transitional epithelium. Extensive neovascularity was evident in the subepithelial layer with a streaming of fibroblasts toward the neomucosa. CONCLUSION: Replacing the avulsed mucosa in the injured ureter with tubularized peritoneal free grafts or bladder mucosal grafts may be an optimal method to manage avulsion of the ureteral mucosa.     

Multiple Oblique Illumination and High-Definition Microscopy for Breast Fine-Needle Aspirates

ABSTRACT We wished to determine whether small-intestinal submucosa (SIS) will epithelialize when used as a ureteral replacement material. An 11-mm segment of native ureter was excised from eight New Zealand White rabbits and replaced with an 11-mm porcine SIS graft, which was circumferentially wrapped around a ureteral stent. The SIS ureteral grafts were harvested at 11 days or 35 days postimplantation and examined grossly and by standard light microscopy techniques. Partial epithelialization with the ingrowth of urothelium, smooth muscle cells, and blood vessels was observed in the grafts harvested at 11 days postimplantation. The SIS ureteral grafts examined at 35 days postimplantation showed additional restructuring of the smooth muscle cell layer and more organized epithelialization in comparison to the SIS graft examined at 11 days. After 35 days of regenerative healing, elements of all three layers of the native ureter were observed within the collagen matrix of the SIS graft. No significant complications were observed, but all subjects (8/8) demonstrated mild intra-abdominal adhesions. Mild collecting system dilatations were observed in 4/4 (100%) of the animals harvested at 35 days and in 0/4 (0%) of the animals harvested at 11 days. We have this demonstrated in this preliminary study that SIS xenografts will epithelialize when used as a ureteral replacement material. The repair mechanism of these ureteral grafts occurred through a regenerative healing process rather than by scar formation. With further studies, this material may prove to be a useful treatment option in patients with ureteral injuries.     

Ureteral segment replacement using a circumferential small-intestinal submucosa xenogenic graft.

We wished to determine whether small-intestinal submucosa (SIS) will epithelialize when used as a ureteral replacement material. An 11-mm segment of native ureter was excised from eight New Zealand White rabbits and replaced with an 11-mm porcine SIS graft, which was circumferentially wrapped around a ureteral stent. The SIS ureteral grafts were harvested at 11 days or 35 days postimplantation and examined grossly and by standard light microscopy techniques. Partial epithelialization with the ingrowth of urothelium, smooth muscle cells, and blood vessels was observed in the grafts harvested at 11 days postimplantation. The SIS ureteral grafts examined at 35 days postimplantation showed additional restructuring of the smooth muscle cell layer and more organized epithelialization in comparison to the SIS graft examined at 11 days. After 35 days of regenerative healing, elements of all three layers of the native ureter were observed within the collagen matrix of the SIS graft. No significant complications were observed, but all subjects (8/8) demonstrated mild intra-abdominal adhesions. Mild collecting system dilatations were observed in 4/4 (100%) of the animals harvested at 35 days and in 0/4 (0%) of the animals harvested at 11 days. We have this demonstrated in this preliminary study that SIS xenografts will epithelialize when used as a ureteral replacement material. The repair mechanism of these ureteral grafts occurred through a regenerative healing process rather than by scar formation. With further studies, this material may prove to be a useful treatment option in patients with ureteral injuries.     

First prize: ureteral segmental replacement revisited

BACKGROUND AND PURPOSE: Long strictures of the proximal ureter are difficult to manage, and circumferential replacement with various natural and synthetic materials has been unsuccessful. We sought to use cultured autologous cells seeded onto graft material for proximal-ureteral replacement. Additionally, we wished to determine if urothelial cell-seeded de-epithelialized small bowel would generate adequate ureteral replacement. MATERIALS AND METHODS: Three sets of experiments were performed. First, autologous pig-bladder smooth-muscle and urothelial cells were expanded in culture on large sheets of multilayer small-intestinal submucosa (SIS). These sheets were then tubularized and used to replace a 5-cm segment of proximal ureter in pigs. Second, autologous cells harvested from the bladders of Beagle dogs were cultured and seeded on porcine ureteral acellular matrix, which was used to replace a 3-cm segment of ureter in dogs. Segments were wrapped in omentum to enhance vascularity. Third, a de-epithelialized small-bowel segment seeded with autologous bladder-epithelial cells was transversally retubularized (Monti) into a 4-cm ureteral replacement. Follow-up studies consisted of retrograde pyelography, serum chemistry assays, hematoxylin/eosin studies, and immunohistopathologic examination using antibodies against alpha-smooth-muscle actin and pancytokeratin AE1-AE3. RESULTS: Coculture of urinary-tract cells on large segments of SIS failed to create adequate ureteral replacement. All grafts were contracted and stenotic, with complete obstruction of the ipsilateral renal unit. Similar results were seen in the Beagles. Despite clinical obstruction and gross contraction of the graft, a circumferential muscular ureteral wall lined with multilayer transitional epithelium was present. Urotheliumseeded de-epithelialized Monti bowel segments resulted in patent ureteral replacement without hydroureteronephrosis and with normal renal function, serum electrolytes, and acid-base balance. However, bowel mucosa fully regenerated, with multilayer transitional epithelium growing adluminally in continuity with the proximal and distal anastomotic sites. CONCLUSIONS: Seeding of ureteral grafts with autologous bladder cells does not promote success in two largeanimal models using different xenogenic acellular matrices. However, muscle and urothelium regeneration occurs with ureteral acellular matrix in the dog. Urothelium-seeded de-epithelialized Monti bowel segments may be an acceptable substitute for long proximal ureteral segments. Further technical refinements are required to replace the bowel mucosa completely with normal urothelium.     

The basilic vein: an alternative drainage of DIEP flap in severe venous congestion

The deep inferior epigastric perforator (DIEP) flap has become a major advance in autologous breast reconstruction, offering all the advantages of free TRAM flap with less donor-site morbidity and postoperative pain. The major drawback threatening the DIEP flap procedure is venous congestion, with potential partial or complete flap loss. Many authors reported different surgical tips aiming to solve this setback, including secondary anastomosis of deep inferior superficial epigastric vein with alternative venous outflow vessels. We present a case report of a DIEP flap salvaged by an alternative venous anastomosis, after comitant veins of the primary anastomosis widely thrombosed a few hours postoperatively. A venous bypass using ipsilateral basilica vein and superficial inferior epigastric vein was fashioned.     

Evaluation of Role of Arterialization of Venous Flaps in Abdomen in Rats

Introduction  Reconstruction forms the primary tenet in plastic surgery. Venous flaps are a known option but the survival is limited. Arterialization of venous flap can enhance its survival. While various techniques of arterialization of venous flaps are described, there are very few studies comparing them. Material and methods  The current study was conducted among 34 rats weighing 160 to 200 grams. The rats were divided into four groups. Group I—islanded epigastric flap was raised with superficial caudal epigastric vessels as pedicle. Group II—arterialized flow through venous flap was raised with superficial caudal epigastric vein (SCEV) as afferent and lateral thoracic vein as drainage vein. Side-to-side anastomosis was done between femoral artery and vein, lateral to the origin of superficial caudal epigastric artery. Group III—after raising the flap, as in group II, femoral vein was ligated proximal to superficial caudal epigastric vessels. Group IV—an arterialized flow through venous flap was raised with superficial caudal epigastric vein as afferent and lateral thoracic vein as drainage vein. End-to-side anastomosis was done between femoral artery and superficial caudal epigastric vein. Animals that died before completion of the study were excluded. The color changes of flaps were noted. Flap survival was expressed as a percentage of the total flap surface area. The patency of anastomosis was seen on postoperative day 5. Results  There was no total flap failure. On statical analysis, the flap survival area on day 5 between Group I and Group IV was not significant ( p value 0.431). The survival area in Group I (78.85 ± 10.54%) was comparable to Group IV (65.71 ± 20.70%). Group II and III had poor results as compared with Group I. In four rats, thrombosis of arteriovenous anastomosis was noted with flap survival area of 30 to 33%. Conclusion  It was noted that epigastric venous flaps with end-to-side anastomosis between femoral artery and superficial caudal epigastric vein (group IV) have survival area comparable to islanded flaps.     

The Use of Recipient Superficial Femoral Vein as a Venous Graft for Portal Vein Reconstruction in Right Lobe Living Donor Liver Transplantation

In living donor liver transplantation (LDLT), portal vein thrombosis (PVT) in the recipient is frequently regarded as a contraindication. To reconstruct the PV of a right-lobe liver graft (RLG) using an interposition or jump graft from the splenomesenteric junction, various vein grafts and technical modifications have been introduced. The internal jugular, external iliac, or great saphenous veins have been utilized in such reconstructive procedures. However, the superficial femoral vein (SFV) is preferable to the autologous vein grafts in terms of caliber, wall thickness, and length. We employed the recipient SFV to reconstruct PVT among 40 adult LDLT using RLG. Thirty-three were reconstructed by single end-to-end anastomosis with the right or left recipient PV. Three patients were transplanted with a RLG using 2 separated PVs reconstructed by double anastomoses with both the right and left PVs of the recipient. The remaining 4 patients required venous grafting for portal reconstruction. We used the recipient SFV as an interposition or jump graft from the splenomesenteric junction to the graft PV. There were 2 cases of anastomotic PV stenosis; 1 in portal reconstruction without a venous graft and the other with a SFV graft. Both were treated successfully by balloon angioplasty. The recipient SFV is an excellent size match for the PV reconstruction as a long interposition or jump conduit when the venous system from the deceased donor is not available. The indication for LDLT in patients with complete PVT should be carefully decided before transplantation in terms of portal reconstruction.     

Effect of vein grafting on the survival of microvascularly transplanted muscle flaps

Since vein grafting is often required during transplantation of free muscle flaps but is associated with a higher failure rate than those flaps transplanted with primary anastomoses, we sought to compare primary repair with the use of vein grafting in an experimental setting. We transplanted the gracilis muscle to the contralateral side in 98 rats using four different methods of vessel repair. In the Control group (n = 28), both femoral vessels were anastomosed primarily. In Experimental Group 1 (n = 25), the femoral artery was anastomosed with an epigastric vein graft and the femoral vein was anastomosed primarily. In Experimental Group 2 (n = 25), the femoral vein was anastomosed with a femoral vein graft and the femoral artery was anastomosed primarily. In Experimental Group 3 (n = 20), both femoral vessels were anastomosed with vein grafts. The Control and Experimental Groups 1–3 survival rates were 89.3, 76.0, 84.0, and 70.0%, respectively; none of the experimental group survival rates was significantly different from that of the control (P < 0.5). This study demonstrates that the use of size-matched, interpositional vein grafts in the arterial or venous pedicle of the rat gracilis muscle flap during transplantation did not significantly decrease flap survival as compared to primary arterial or venous anastomoses. If the observed failure rate persisted with expansion of the study groups to 60–100 animals each, the failure rate of flaps with vein grafts would be significantly lower and comparable to failure rates reported in some clinical series. The large numbers necessary to significantly show this decrease make this model impractical for further studies © 1997 Wiley-Liss, Inc. MICROSURGERY 17:512–516 1996     

Morphologic changes in the canine urinary tract after ureteral reconstruction with the tunica albuginea (experimental study)*

Objectives: The problem of ureteral reconstruction has not been fully solved, despite dramatic developments in surgical methods. Many attempts to repair a ureteral damage with autologous or homologous organ grafts, or with organic substitutes have not really been satisfactory. Also, attempts to use alloplastic and heteroplastic prostheses made of synthetic materials have been equally disappointing. Experimental studies, particularly in dogs, indicate great regenerative abilities of ureters when appropriate surgical techniques are used. Materials and methods: In our experimental study, suitability of the tunica albuginea for reconstruction of the middle part of the ureter was investigated in 20 dogs. The dogs were divided into two groups according to a type of ureteral damage: partial (a patch graft) or complete (a tube graft). The ureteral damage was 2–3 cm long in 10 dogs and 3–3.5 cm long in the subsequent 10 dogs. Each dog underwent two operations. The first operation involved a fenestrating incision in the ureter, 23.5 cm long, so as to preserve the ureteral continuity, and then the produced injury was repaired with a patch of the tunica albuginea, with the 4 Charr catheter being inserted in the ureter. The second operation involved a complete excision of ureteral segments, 2–3.5 cm long, on the contralateral side. The excised length of the ureter was substituted with a tube graft of the tunica albuginea, also using the 4 Charr catheter. Thus, in 21 cases, a partial damage of the ureteral wall was repaired with a patch graft of the tunica albuginea. In 19 cases, a complete damage of the ureter was repaired with a tube graft of the tunica albuginea. Results: Four dogs died after the tube-graft implantation due to urinary infiltration and/or purulent inflammatory changes in the kidneys. Autopsies were performed in all the dogs after they had been put to sleep. Definitely poor results were obtained in case of the complete reconstruction of the ureteral loss with a tube graft of the tunica albuginea, 3–3.5 cm long. Within the graft area, we observed inflammatory infiltrates of varied intensity, fibrosis, cicatricial strictures or ureteral obstruction. Occasionally, necrotic foci, degenerative changes or hydronephrosis were found. In case of the reconstruction with a shorter tube graft, i.e. 2–3 cm long, similar changes were observed, however, they were less intense. Satisfactory results were obtained following the partial reconstruction of the ureteral loss with a patch graft of the tunica albuginea. In this case, we observed generally normal regeneration not only of the transitional epithelium but the muscular layer and ureteral structure as well, with full patency of the ureter preserved. The findings obtained in our study are compatible with the findings of other authors. Conclusions: (1) The success of reconstructive procedures in the ureters can be achieved if the continuity of the ureter is preserved and the catheter is removed after 14 days. (2) The substitution of a complete ureteral loss with a tube-graft of the tunica albuginea results in necrosis of the graft and restenosis. *Printed in part at the postdoctoral thesis of Tyloch Ferdynand MD: “An experimental study on the use of tunica albuginea for supplying at westage of ureters” (Badania doswiadczalne nad przydatnoscia blony bialawej jadra w operacjach plastycznych moczowodu) University School of Medical Sciences Bydgoszcz 1994.     

Salvage of congested deep inferior epigastric perforator flap with a reverse flow venous anastomosis

The deep inferior epigastric perforator flap (DIEP) is an increasingly popular method for autologous breast reconstruction because of less abdominal wall donor-site morbidity. However, disadvantages with the DIEP flap are its greater technical difficulties for flap harvest and a greater incidence of venous congestion. We report a case of salvage of a congested DIEP flap with a superficial inferior epigastric vein (SIEV) to deep inferior epigastric vein reverse flow anastomosis. Drainage of both the superficial and deep system resulted in complete reversal of venous congestion and flap salvage. Preservation and use of the SIEV for venous augmentation via a reverse flow anastomosis is a novel and simple method for DIEP flap salvage of venous congestion.     

Pyeloureterostomy with interposition of the appendix

PURPOSE: We describe the successful repair of a 6 cm. ureteral stricture involving the right ureteropelvic junction and proximal ureter using appendix as a ureteral substitute. MATERIALS AND METHODS: A 37-year-old man involved in a motorcycle accident presented with a retroperitoneal urinoma and a 6 cm. proximal ureteral stricture. At flank exploration we were unable to perform successfully primary pyeloureterostomy through renal descensus with ureteral mobilization. The appendix was selected to bridge the ureteral defect. The right colon and cecum were mobilized to the area of the diseased ureter and the appendix was transected across the base of the cecum. Ureteral scar tissue was resected and the appendix was interposed in an isoperistaltic orientation from renal pelvis to proximal ureter. RESULTS: Convalescence was unremarkable. Retrograde pyelography and flexible ureteroscopy 2 months postoperatively demonstrated a patent anastomosis and viable appendix. The ureteral stent was removed at that time. Excretory urography 3 months postoperatively revealed prompt enhancement of the 2 kidneys and visualization of the 2 ureters. Mercaptoacetyltriglycine-3 renal scan 5 months postoperatively confirmed no scintigraphic evidence of obstruction. The patient was asymptomatic 6 months postoperatively and renal function tests were normal. CONCLUSIONS: The appendix can be considered for proximal ureteral defects extending to the right renal pelvis.     

Rat femoral vein-to-vein grafts as a microvascular practice model: factors that influence patency

The rat femoral vein has become a standard model for microvascular anastomosis practice as well as for research investigations into various manipulative influences upon venous patency. Although vein grafts to the rat artery are the focus of many experimental studies, few reports have investigated vein-to-vein grafts. This study examines the short-term patency (1-3 days) of vein grafts interpositioned to the rat femoral vein. Several factors are studied for their ability to alter the patency rate. The results indicate that patency is difficult to achieve following the creation of a second serial anastomosis (construction of a vein-to-vein graft). Systemic heparin consistently improves patency rates, and trends toward increased patency are seen for reduction in longitudinal tension of the repaired vessel. It is also implied that a deeper understanding of venous hemodynamics and thrombotic events may lead to improved methodologies in the clinical applications of microvenous repairs. These results indicate that rat vein-to-vein grafts may provide a challenging microvascular training model, while introducing the novice microsurgeon to some of the complicating factors encountered with microvascular grafting.     

Laparoscopic replacement of urinary tract segments using biodegradable materials in a large-animal model.

OBJECTIVE: We elected to evaluate laparoscopic segmental bladder and ureteral replacement with free biodegradable graft materials in a large-animal model. MATERIALS AND METHODS: In 18 Yucatan minipigs, a 1.5- to 2.8-cm segment of the upper ureter was excised. In 15 study animals, the ureter was laparoscopically replaced: by a stinted (6F double-J stent) tube graft made of acellular matrix (AMX) prepared from minipig ureters (MUMX) in 6 animals, acellular matrix prepared from domestic pig ureters (DUMX) in 3, and small-intestinal submucosa (SIS) in 6. In 3 control animals, the ureteral gap was bridged only by an indwelling stent. The stent was removed at 6 weeks, and retrograde ureteropyelography was performed preoperatively and at 8 and 12 weeks postoperatively, when animals were sacrificed. In 18 Yucatan minipigs, 3 x 3-cm bladder dome segments were laparoscopically replaced: by acellular matrix prepared from minipig small bowel (MBMX) in 6 animals, and SIS in 6 animals. The bladder was closed primarily in 6 control animals. Bladder capacity was assessed preoperatively and at 6 and at 12 weeks, when the animals were sacrificed. RESULTS: The average operating time for ureteral replacement was 187 (range 105-360) minutes. At 12 weeks, all animals had complete obstruction at the level of the replacement, with fibrosis +/- bone formation at the level of the stricture. For the bladder replacement groups, the average operating time was 147 (range 85-200) minutes. At 12 weeks, the bladder capacity was 60% of the preoperative capacity in the control group, 118% in the MBMX group, and 142% in the SIS group. Histologic examination showed regeneration of urothelium and some muscle with both MBMX and SIS. CONCLUSIONS: We were able to develop a reliable laparoscopic technique for both segmental ureteral and partial bladder replacement in a porcine model. With AMX and SIS replacement, regeneration of urothelium occurred in both ureter and bladder. However, functional replacement was successful only in the bladder.     

The axillocoronary bypass. Blood flow and short-term graft histology in a porcine model

BACKGROUND: Bypass grafts arising from the axillary artery may be indicated for complications during minimally invasive direct coronary artery bypass grafting, for redo operations and for management of a severely atherosclerotic ascending aorta. As basic data research on this technique is scanty, we investigated intraoperative function and postoperative morphology of axillocoronary bypass grafts in a porcine model. METHODS: Thirteen German domestic pigs received an axillocoronary vein graft (Group I, n=7) or an aortocoronary vein graft (Group II, n=6) to the left anterior descending artery. In Group I the proximal anastomosis was performed to the left axillary artery, and after partial rib resection the graft was brought transpleurally to the target vessel. In both groups the coronary anastomosis was carried out on the beating heart without cardiopulmonary bypass. Graft flow was measured using transit time ultrasonic flow probes. RESULTS: Intraoperatively all grafts showed a typical diastolic flow profile. Stable graft flow was lower in axillocoronary bypass grafts: 47 (30-60 mL/min) in Group I and 65 (35-126 mL/min) in Group II (p=0.005). Flow given as percentage of cardiac output, however, did not differ between the two grafts: 0.9 (0.6-1.2%) in Group I and 1.2 (0.8-2.4%) in Group II (p=NS). At day 4 after surgery there was no clear histologic predilection site for microtrauma and early degenerative changes in the axillocoronary graft. CONCLUSIONS: Axillocoronary bypass flow compares well with flow in the aortocoronary graft. Microtrauma after implantation and early degenerative changes in the axillocoronary vein bypass are not particularly impacted by the thoracic entry site.     

Use of single layer small intestinal submucosa for long segment ureteral replacement: a pilot study

PURPOSE: Previous studies have demonstrated successful use of small intestinal submucosa (SIS) as a tube for replacing short segment (11 mm) proximal ureteral defects. However, such small segment ureteral defects could be managed by resection re-anastomosis. We evaluated the use of 1-layer SIS as a tube for the replacement of long segment ureteral defects. MATERIALS AND METHODS: The ureters of 5 female mongrel dogs were accessed through a median laparotomy incision. A 4 cm segment of mid ureter was resected on the right side. The right ureteral segments were replaced by tubularized SIS segments using 6-zero polydioxanone interrupted sutures. Internal pigtail stents were left for 6 weeks. All animals were sacrificed at 12 weeks. Ureteral patency was assessed by excretory urography and magnetic resonance urography 7 and 12 weeks after the initial procedures. Inflammation and regeneration were assessed histologically. RESULTS: At 12 weeks all ureters on the experimental side were completely occluded with significant hydroureteronephrosis and the subsequent deterioration of kidney function. At autopsy there was failure to calibrate any of the experimental ureters with a 3Fr catheter. Although histologically urothelium and muscular cells had proliferated over the graft, they were embedded in an intense fibrotic and inflammatory process. CONCLUSIONS: Technically 1-layer SIS was easily modeled, providing the conditions for watertight anastomosis. The regeneration of urothelium and muscle was induced and supported by the graft. However, functional replacement was not successful. One-layer SIS is not a suitable material for replacing long segment (4 cm) ureteral defects.     

A New Technique for Reconstruction of the Common Bile Duct by an Autologous Vein Graft and a Biodegradable Endoluminal Stent

The incidence of severe bile duct injuries has significantly increased since the introduction of laparoscopic cholecystectomy. The ideal reconstruction procedure for traumatic defects of the bile duct should be technically simple and should preserve both the physiological passage of bile and the sphincter of Oddi. In this article we describe a new technique for bile duct reconstruction in a pig model by means of an autologous vein graft that is splinted by a endoluminal biodegradable polylactate acid stent. In 12 pigs the external jugular vein was removed and used as an autologous vein graft. After performing a median laparotomy a 2-cm segment was resected from the bile duct. The common bile duct was reconstructed by a venous interponate that had been endoluminally stented by a biodegradable polylactate acid stent. For the examination of stent degradation, 2 pigs were sacrificed at 3, 4, and 5 months (stent degradation group) and the remaining 6 pigs at 6 months (survival group). All the pigs in the survival group survived for 6 months before being sacrificed. After 4 months the stent material had been completely broken down and the vein graft had been relined with bile duct epithelium. Thus, this new technique for bile duct reconstruction using an autologous vein graft with an endoluminal stent is simple to perform and reliable, and constitutes an interesting alternative to bilodigestive anastomosis due to the preservation of the papilla of Vateri.     

A new technique for reconstruction of the common bile duct by an autologous vein graft and a biodegradable endoluminal stent.

The incidence of severe bile duct injuries has significantly increased since the introduction of laparoscopic cholecystectomy. The ideal reconstruction procedure for traumatic defects of the bile duct should be technically simple and should preserve both the physiological passage of bile and the sphincter of Oddi. In this article we describe a new technique for bile duct reconstruction in a pig model by means of an autologous vein graft that is splinted by a endoluminal biodegradable polylactate acid stent. In 12 pigs the external jugular vein was removed and used as an autologous vein graft. After performing a median laparotomy a 2-cm segment was resected from the bile duct. The common bile duct was reconstructed by a venous interponate that had been endoluminally stented by a biodegradable polylactate acid stent. For the examination of stent degradation, 2 pigs were sacrificed at 3, 4, and 5 months (stent degradation group) and the remaining 6 pigs at 6 months (survival group). All the pigs in the survival group survived for 6 months before being sacrificed. After 4 months the stent material had been completely broken down and the vein graft had been relined with bile duct epithelium. Thus, this new technique for bile duct reconstruction using an autologous vein graft with an endoluminal stent is simple to perform and reliable, and constitutes an interesting alternative to bilodigestive anastomosis due to the preservation of the papilla of Vateri.