Surgical technique in the rat model of kidney transplantation

Today successful kidney transplantation procedures, techniques and immunosuppression protocols are a consequence of extensive research on animal models. During every transplantation surgery there are two crucial points for the success of the entire procedure: vascular (arterial end venous) and ureteral or ureterovesical anastomosis. Renal artery and vein of the donor kidney can be anastomosed end-to-side to the abdominal aorta and vena cava of the recipient (heterotopic transplantation), or end-to-end to the remains of renal artery and vain of the recipient (orthotopic transplantation) after nephrectomy. The ureter can be anastomosed also end-to-end or we can connect it directly to the urinary bladder (ureterocystoneostomy). The aim of this study was to elucidate which technique has better results according to: animal survival, reperfusion and perfusion of the transplanted kidney, elimination of the urine from the transplanted kidney and procedure costs. The study included 240 (120 donors and 120 recipients) male Wistar rats (3 months old; weight 250-300 g Our results are clearly showing that the end-to-end vascular anastomosis, and Paquins ureterovesical anastomosis have better results in transplanted rat kidneys survival and urine drainage compared to end-to-side vascular anastomosis and end-to-end ureteral anastomosis. Based on our experience we can conclude that described methods of end-to-end vascular anastomosis and Paquins ureterovesical anastomosis are less technically demanding and have a shorter learning curve. Therefore, we can recommend the use of described methods in kidney transplantation related researches.     

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.     

A new technique for microvascular anastomosis: external metallic circle

Vessel anastomosis is the most critical step in free tissue transfers and replantation surgery. We report on a new microvascular anastomosis technique that uses a metallic circle around the anastomotic circumference. Sutures are first passed inside the circle and tied outside and over the circle so as to stretch open the anastomotic site. By retraction of vessel ends, the circle is totally exteriorized and thus there is no contact with blood. In 48 rats, the external circle method was compared with the conventional technique for constructing end-to-end anastomosis between carotid arteries (1 to 1.2 mm) and femoral veins (1 to 1.5 mm). The external circle method proved to be superior to the conventional end-to-end technique in speed of execution for both arterial and venous anastomoses. Patency rates at the third week were significantly higher in the venous group using the metallic circle (100 percent versus 70.8 percent, p < 0.05). This new method may be applicable in clinical microvascular surgery.     

The Diagnosis and Treatment of Arterial Injuries

Repair of arterial injuries has decreased the amputation rate to 15% from 50%, which was prevalent when ligation was practised. Methods of treatment include lateral repair, resection of damaged area with end-to-end anastomosis, and resection and graft, with or without the assistance of partial or complete cardiopulmonary bypass. Lacerations of large arteries (aorta, iliac) may be treated by lateral repair. Lacerations of smaller arteries are best treated by resection and anastomosis, or by resection and graft. True and false aneurysms and arteriovenous fistulas are best treated by resection and restoration of blood flow. “Spasm” in an artery is frequently due to intimal rupture or subintimal hemorrhage, and likewise requires resection and anastomosis in many instances. Clinical examples of each type of injury are presented. Angiography is of great value in establishing the precise abnormality present, its location, the degree of collateral circulation, and the result achieved by surgery.     

食蟹猴肾移植模型的建立

目的建立食蟹猴的肾移植模型。方法通过显微外科手术对食蟹猴进行同种异体移植,将供体肾动脉、肾静脉分别端侧吻合到受体腹主动脉、下腔静脉,供体输尿管端端吻合到受体输尿管。结果154例肾移植食蟹猴无一只在手术过程中因意外死亡;无一只因手术感染死亡;无一只因手术并发症死亡;肾热缺血时间（30±4.5）min。结论应用食蟹猴建立肾移植模型,技术成熟,方法可靠。应用此模型评价新型免疫抑制药物,进行免疫耐受、异种移植研究可为临床试验提供更为准确可靠的依据。     

Hemodynamic analysis of Hyrtl anastomosis in human placenta

The Hyrtl anastomosis is a common connection between the umbilical arteries near the cord insertion in most human placentas. It has been speculated that it equalizes the blood pressure between the territories supplied by the umbilical arteries. However, its functional role in the regulation and distribution of fetal blood flow to the placenta has not yet been explored. A computational model has been developed for quantitative analysis of hemodynamic characteristic of the Hyrtl anastomosis in cases of discordant blood flow in the umbilical arteries. Simulations were performed for cases of either increased placental resistance at the downstream end or reduced arterial blood flow due to some pathologies upstream of one of the arteries. The results indicate that when placental territories of one artery impose increased resistance to fetal blood flow, the Hyrtl anastomosis redistributes the blood flow into the second artery to reduce the large pressure gradients that are developed in the affected artery. When one of the arteries conducts a smaller blood flow into the placenta and a relatively smaller pressure gradient is developed, the Hyrtl anastomosis rebuilds the pressure gradients in the affected artery and redistributes blood flow from the unaffected artery to the affected one to improve placental perfusion. In conclusion, the Hyrtl anastomosis plays the role of either a safety valve or a pressure stabilizer between the umbilical arteries at the placental insertion.     

Transplantation of both kidneys from one donor rat

We have developed a technique for harvesting and transplanting two kidneys from one donor rat. Our method involves end-to-end anastomosis of the renal artery and the renal vein. Because of the short distance between the caudal vena cava and the right kidney, renal transplantation is not feasible on the right side of the recipient. The right donor kidney was therefore transplanted to the left side. Graft morphology was assessed on paraffin sections. We observed no differences between conventionally transplanted kidneys (n = 116) and right kidneys transplanted according to the method described (n = 40). In conclusion, our technique is simple, saves time and reduces the number of donor rats.     

Experiences of Microsurgical Reconstruction for Variant Hepatic Artery in Living Donor Liver Transplantation

There is an emergent need for improving the microsurgical technique of variant arterial anastomosis to reduce the often seen surgery-related complications. We describe in this article our experience in improving this technique, in 73 living donor liver grafts (64 right lobes, 9 left lobes) in patients with end-stage liver disease during living donor liver transplantation. The hepatic arteries were evaluated preoperatively with computed tomography and magnetic resonance angiography. In this series, 13 grafts (17.80 %) with variant hepatic artery were conducted arterioplasty on a back-table under a loupe or a high-power microscope, which included one recipient in situ interposition vessel graft of recipient proper hepatic artery for artery reconstruction. The back-table reconstruction time was 16 ± 5.6 min. No arterial thrombosis was found in these cases during the 6-month postoperative follow-up. On the basis of our experience, we suggest that back-table microsurgical plasty for graft with arterial variation should be applied to minimize operative difficulties and to avoid arterial complications in living donor liver transplantation.     

Anomalous origin of the left coronary artery from the pulmonary artery treated by palliative Vineberg operation in an infant

Anomalous origin of the left coronary artery from the pulmonary artery was diagnosed in an infant girl who had evidence of transmural myocardial infarction of the free wall of the left ventricle. At age 13 months, she underwent a palliative left Vineberg implant, and remained asymptomatic until she was 8 years of age. At that time, she underwent suturing of the left coronary ostium for obliteration of the left coronary shunt at the pulmonary artery. At age 13, she underwent aortocoronary bypass to the left main coronary artery, with end-to-end anastomosis. The patient remains asymptomatic to date. We believe that this is the first reported case of a Vineberg operation performed in an infant for palliation of an anomalous left coronary artery originating from the pulmonary artery. This method allows time for the development of collateral circulation to the left coronary artery before definitive surgery is performed.     

Distally based free flap using retrograde arterial flow

In lower extremity injuries, the major arteries are frequently damaged and the remaining artery may be located in the traumatized zone. Recently, vascular anastomoses to recipient vessels distal to the zone of injuries have been advocated in the lower limb reconstruction and flaps by using retrograde arterial flow are well established in island flaps. Twelve patients with soft-tissue defects below the knee underwent lower extremity reconstruction with distally based free flaps by using retrograde arterial flow. For assessment of retrograde flow, the intraoperative retrograde arterial pressure was quantitated and compared with the systolic blood pressure taken at the same time (n = 6). In this study, suitable candidates had been chosen with pulsatile retrograde flow from the distal cut end of the vessel because patients without pulsatile flow had recorded diastolic and systolic retrograde arterial pressures that were very low. Four different free flaps were used. All flaps were successful. Retrograde flow anastomosis could not interrupt the major blood vessels, which were essential for survival of the distal limb, the compromise of fracture or wound healing might be prevented. In cases in which arteriography demonstrates significant vascular flow interruption within the zone of injury, retrograde arterial anastomosis may also be a candidate.     

The effects of tapering and artery wall stiffness on treatments for Coarctation of the Aorta

Coarctation of the Aorta is a congenital narrowing of the aorta. Two commonly used treatments are resection and end-to-end anastomosis, and stent placements. We simulate blood flow through one-dimensional models of aortas. Different artery stiffnesses, due to treatments, are included in our model, and used to compare blood flow properties in the treated aortas. We expand our previously published model to include the natural tapering of aortas. We look at change in aorta wall radius, blood pressure and blood flow velocity, and find that, of the two treatments, the resection and end-to-end anastomosis treatment more closely matches healthy aortas.     

Arterial T and Y grafts.

Presented is the use of an autogenous arterial T graft for the salvage of a thrombosed arterial end-to-side anastomosis. The T-graft concept also offers the possibility of replacing a segment of artery in patients with arterial vessel wall defects, stenosis, obliteration, or disease during free latissimus dorsi or scapular flap transfer. The arterial T graft is harvested from the axilla and consists of segments of the subscapular, circumflex scapular, and thoracodorsal arteries. The large diameter of these vessels offers a good match with the arteries of the lower leg and forearm. The arterial Y graft consists of the same arteries and is used as an interpositional graft to revascularize two distal vessels from one proximal vessel.     

Algorithm for recipient vessel selection in free tissue transfer to the lower extremity.

The proper selection of a recipient vessel is essential for the success of free tissue transfer, especially when the transfer is to the lower extremity. However, a general agreement on which vessel to use has not been reached yet. Conflicting data have been reported on the survival and outcome of the transferred flaps, depending on the vessel used or the location of anastomosis. The aim of this study was to identify the patterns and problems in the selection of recipient vessels for free tissue transfer to the lower extremity and to establish a general guideline for proper selection. From September of 1990 to December of 1997, 50 consecutive, microvascular, free tissue transfers were performed on the lower extremity. The causes requiring soft-tissue coverage included trauma (25), unstable scar (11), chronic osteomyelitis (7), and tumors (7). The mean follow-up period was 22.4 months (range, 2 to 41 months). In 25 cases, the posterior tibial vessel was used as the recipient vessel. The microvascular anastomosis was done proximal to the zone of injury in 45 cases. The two most important factors in the selection of a recipient vessel are the site of injury and the vascular status of the lower extremity. Less important factors include the flap to be used, method, and site of microvascular anastomosis. All the currently feasible options for recipient vessels are included, and the opinions of other surgeons are reviewed. A general guideline is established, and an algorithm for the proper selection of a recipient vessel is proposed. This algorithm is a fast and convenient guide for evaluating the wound and planning the free flap to the lower extremity.     

Rotational in vitro compliance measurement of diverse anastomotic configurations: a tool for anastomotic engineering

Anastomotic configurations with a small internal diameter are prone to intimal hyperplasia which can cause occlusion within weeks or months. A link between intimal hyperplasia and inhomogenities of the elastic profile of the anastomosis has been established, making anastomotic engineering directed towards smoothing the compliance profile at the anastomotic site essential. Methods to date restrict the anastomotic compliance measurement to one plane. We present a method by which the anastomotic configurations are rotated, thereby allowing an anastomotic elastic profile assessment in multiple planes. Eight end-to-end anastomoses (ovine common carotid artery) and three end-to-side anastomoses (e-PTFE graft to ovine common carotid artery) were prepared and mounted in an artificial circulation system. Anastomotic circumferential compliance (maximal-minimal diameter/(maximal-minimal pressure.minimal diameter)) was measured by means of a laser-scan-micrometer and a Statham pressure transducer. By rotating end-to-end anastomoses, the compliance was measured in three, and in end-to-side anastomoses in four different planes. Multiplanar compliance variability in areas remote to both end-to-end and end-to-side anastomoses was approximately 9%. At the suture line the variability was approximately 22% in end-to-end anastomoses and 78% in end-to-side anastomoses. These results show that local factors result in different compliance profiles when utilizing a multiplanar technique, particularly in end-to-side anastomoses. The rotational apparatus is a tool which can be used to more accurately engineer a homogeneously compliant anastomosis, with the ultimate goal of prolonging anastomotic patency.     

硬膜外导管在大鼠肾移植血管吻合中的应用

目的建立一种手术难度低,成功率高的大鼠肾移植模型。方法 Wistar大鼠作供体,SD大鼠作受体,将供体腔静脉与受体肾静脉端端吻合,供体腹主动脉与受体腹主动脉端侧吻合,供体膀胱瓣与受体膀胱吻合。根据血管吻合时应用硬膜外导管与否,将受体分为有支架组和无支架组两组。结果有支架组共进行肾移植30次,成活26只;无支架组共进行肾移植20次,成活10只。有支架组的成活率86.7%（26/30）较无支架组50.0%（10/20）明显提高（P〈0.05）,血管吻合总时间（22±2）min较无支架组（32±2）min明显缩短（P〈0.05）。结论硬膜外导管应用于大鼠肾移植血管吻合,降低了手术难度,减少了吻合口出血,提高了手术成功率。     

Heterotopic heart transplantation in mice

The mouse heterotopic heart transplantation has been used widely since it was introduced by Drs. Corry and Russell in 1973. It is particularly valuable for studying rejection and immune response now that newer transgenic and gene knockout mice are available, and a large number of immunologic reagents have been developed. The heart transplant model is less stringent than the skin transplant models, although technically more challenging. We have developed a modified technique and have completed over 1000 successful cases of heterotopic heart transplantation in mice. When making anastomosis of the ascending aorta and abdominal aorta, two stay sutures are placed at the proximal and distal apexes of recipient abdominal aorta with the donor s ascending aorta, then using 11-0 suture for anastomosis on both side of aorta with continuing sutures. The stay sutures make the anastomosis easier and 11-0 is an ideal suture size to avoid bleeding and thrombosis.When making anastomosis of pulmonary artery and inferior vena cava, two stay sutures are made at the proximal apex and distal apex of the recipient s inferior vena cava with the donor s pulmonary artery. The left wall of the inferior vena cava and donor s pulmonary artery is closed with continuing sutures in the inside of the inferior vena cava after, one knot with the proximal apex stay suture the right wall of the inferior vena cava and the donor s pulmonary artery are closed with continuing sutures outside the inferior vena cave with 10-0 sutures. This method is easier to perform because anastomosis is made just on the one side of the inferior vena cava and 10-0 sutures is the right size to avoid bleeding and thrombosis. In this article, we provide details of the technique to supplement the video.     

Usefulness of a first transferred free flap vascular pedicle for secondary microvascular reconstruction in the head and neck

The authors found that a previously transferred free flap vascular pedicle, distal to the first microvascular anastomosis, can be used as a recipient vessel for an additional free flap transfer. Free flap transfers were performed by using the standard procedure in patients with head and neck cancer. The mean age of the patients was 62 years. Five patients were men and three were women. A second free flap was transferred for secondary primary head and neck cancer in two cases, facial deformity in two cases, osteomyelitis of the skull in two cases, recurrent cancer in one case, and exposure of a mandibular reconstruction plate in one case. The interval between the two operations was from 4 months to 12 years (median, 21 months). All secondary free flaps were performed successfully. In two cases, the external jugular vein proximal to the previously anastomosed site was used for venous drainage. In another case, additional venous anastomosis was performed for flap congestion. It became clear that a previously transferred free flap vascular pedicle could be used as a recipient vessel for microvascular anastomosis. This is an excellent procedure for additional free flap transfers.     

兔颈动、静脉移植桥血管狭窄模型的建立及其电镜观察

目的：建立兔颈动、静脉移植血管桥动物模型,观察移植桥血管内膜增生和狭窄的电镜下表现。方法：通过兔双侧颈动脉进行动脉桥和静脉桥的移植,形成双侧移植血管桥再狭窄动物模型。在第8周施行血管桥移植手术的同时留取右侧颈动静脉标本作为对照血管,再分别于第12周、16周和第20周分别处死模型兔,采集移植桥血管标本,在光镜下测量其内膜厚度、面积、狭窄度,并进行电镜观察。结果：颈动脉和颈静脉桥移植后,随着时间的延长,桥血管的出现平滑肌迁移,脂质沉积,内膜增生,血管狭窄等改变,且以静脉桥血管的病理改变更为明显。结论：在兔形成动脉粥样硬化病变基础上,进行双侧颈动脉血管桥的移植,建立兔双侧颈动脉移植血管桥再狭窄动物模型,有利于设立自身对照,研究术后动静脉桥再狭窄差异机制;建立动、静脉桥后,位于血管中膜的平滑肌细胞出现向血管内膜迁移现象,说明中膜平滑肌细胞迁移进入内膜导致新内膜形成是血管再狭窄的重要环节。     

Comparison of vascular hemodynamics in experimental models of microvascular anastomoses

Blood flow was measured in the canine saphenous artery using electromagnetic flowmetry. Significant increase in blood flow was noted after occlusion of the distal femoral artery. However, after raising a saphenous island flap there was no significant change in the blood flow before and after distal femoral artery occlusion. The flap peripheral resistance and blood flow were compared after end-to-end and end-to-side anastomosis and no statistical difference was noted.     

Design and fabrication of a mechanically matched vascular graft

The study provides a pathway to design a mechanics-matching vascular graft for an end-to-end anastomosis to a host artery. For functional equivalence, we submit that the graft and a host artery should have equal inner deformed diameters, equal pressure-radius module, and experience equal axial forces when subjected to mean arterial pressure. These criteria for mechanical equivalence are valid for a large class of materials that can be considered as elastic incompressible and orthotropic solids. As an example, specific known artery properties were used to design or select a graft made from a new synthetic biomaterial to demonstrate that reliable and robust technology for graft fabrication is possible.