Microsurgical repair after crush-avulsion injury of the femoral vein in rats: prevention of microvascular thrombosis with recombinant human tissue-type plasminogen activator (rt-PA).

Vein thrombosis is often encountered in microsurgery, especially in the case of crush-avulsion injuries. The aim of this study was to investigate the effect of systemic administration of recombinant tissue-type plasminogen activator (rt-PA) on the patency of the femoral vein of the rat, which had previously sustained a crush-avulsion injury. The study consisted of 3 groups of male Wistar rats, 20 animals each. A standardized crush-avulsion injury model was used. After microvascular repair of the femoral vein, the animals received either normal saline (group A), heparin 100 U/kg body weight (group B), or rt-PA 3.5 mg/kg body weight (group C) systemically. Patency tests were performed at 20 minutes, 48 hours, and 1 week after blood flow reestablishment. According to our results, the patency rate of the rt-PA group was significantly higher than in both the control and heparin groups.     

Effects of enoxaparin,standard heparin,and streptokinase on the patency of anastomoses in severely crushed arteries

The effects of topical irrigation with three antithrombotic agents on the patency of anastomosed arteries following crush injury were examined. Following an impact crush injury with a 25 kg crush load, the femoral arteries of rats were divided and then anastomosed. During anastomoses, the vessel lumina were topically irrigated with saline, streptokinase, standard heparin, or enoxaparin (a low molecular weight heparin). The results were evaluated by patency test and histology up to day 56. The thrombosis rate at days 1 and 7 was statistically lower (P<0.05) in the standard heparin and the enoxaparin groups than in the other two groups. The difference between the standard heparin and the enoxaparin groups was not statistically significant. Histology at day 1 showed that thrombus in the occluded vessels adhered to the exposed adventitia in the crushed area or the adventitia was covered by fibrin, red blood cells, and platelet mesh in the patent vessels. The results showed that 1) topical irrigation with standard heparin or enoxaparin solution significantly reduced the thrombosis rate at the anastomosis site of the crushed arteries; and 2) enoxaparin was as effective an antithrombotic agent as standard heparin when topically applied during microvascular anastomoses. © 1995 Wiley-Liss, Inc.     

Microvenous thrombosis rates following anastomosis with vein grafting and a knotted suture

An experimental microvenous thrombosis model was developed combining vein grafting in femoral vein defects with exaggerated vessel injuries using a knotted suture in the vessel repair. The rat femoral vein grafts were separately subjected to injuries caused by an anastomosis performed with a suture knotted with eight half-hitches at the distal anastomosis (upstream), the proximal anastomosis (downstream), and both anastomotic sites. These groups were compared to vein grafting done with a standard suture. Vessel patency was assessed at 20 min and 24 hr, and the thrombus component was histologically analyzed at 24 hr after the procedures. One hundred percent of control vein grafts were patent at 24 hr. All experimental groups had significantly decreased patency at 24 hr (P<0.001). Among the experimental groups, knotted suture anastomoses at both anastomoses produced significantly lower patency (13.3%, P<0.05) than knotted suture anastomoses at distal anastomoses. Histological analyses of thrombosed grafts showed that a large amount of thrombocyte deposition and inflammatory cells were noted at both anastomotic sites in the vein grafts with a knotted suture at the distal anastomosis and in the grafts with a knotted suture at both anastomoses. Thrombocyte deposition and inflammatory cells were seen only at the site of proximal anastomosis when using a knotted suture at the proximal anastomosis site alone. This study demonstrated that quantified microvenous thrombosis can be produced by exaggerating vessel injuries with a knotted suture in a vein graft model. This thrombosis model can be used to study the effects of antithrombogenic agents. © 1995 Wiley-Liss, Inc.     

Microvascular repair following a modified crush-avulsion injury in a rat model: effect of recombinant human tissue-type plasminogen activator on the patency rate

The failure rate of replantations following a crush-avulsion type injury is high. This study has been designed to reproduce an effective standardized crush-avulsion injury model to the femoral artery of the rat and evaluate the antithrombotic efficacy of systemic intravenous administration of recombinant human tissue-type plasminogen activator (rt-PA). The crush-avulsion injury was reproduced by using a bulldog clamp and two hemostats and followed by microvascular repair. The animals were divided into three groups of 20 rats each and received either normal saline, heparin 100 U/kg body weight, or rt-PA 3.5 mg/kg body weight intravenously. Patency tests were performed 20 min and 48 h after blood flow reestablishment. Results showed that this experimental crush-avulsion injury model ensures low patency in the control group, whereas systemic rt-PA administration improves the patency rate statistically significantly compared to control and heparin groups at both 20 min and 48 h postrevascularization.     

Experience with Cryopreserved Cadaveric Femoral Vein Allografts Used for Hemodialysis Access

The purpose of this study was to review the patency and complications of cryopreserved vein allografts used for hemodialysis access, and to compare them to a group with polytetrafluoroethylene (PTFE) grafts. Patients without adequate vasculature for native fistula were implanted with vein allografts or PTFE grafts at the surgeons discretion. Only cryopreserved (CRY) veins were used until January 2001, when decellularized, cryopreserved Synergraft (SYN) veins became available. The CRY group had 48 patients; the SYN group, 42 patients; the PTFE group, 100 patients, who were selected from billing records listing PTFE graft insertion. Patient demographics were similar. Primary and secondary patencies were not significantly different at 1 or 2 years between groups. Complications in PTFE versus CRY and SYN groups were as follows: infection, 10 % vs. 0% (p < 0.01); aneurysm, 2% vs. 18% (p < 0.001); and steal syndrome, 12% vs. 12% (p = NS). Significantly more vein allograft patients lost their accesses to aneurysm (p < 0.01) and multiple stenoses (p < 0.05), whereas PTFE patients lost significantly more accesses to infection (p < 0.01) and recurrent thrombosis (p < 0.05). We conclude that cadaver vein allografts have similar patency to PTFE grafts. These allografts are more resistant to infection but significantly more susceptible to aneurysms. When used, vein allografts should be monitored aggressively for the development of aneurysms.Abstract presented at the 84th Annual Meeting of the New England Surgical Society, Newport, RI, September 19, 2003, and American Society of Nephrology 36th Annual Meeting, San Diego, CA, November 12, 2003.     

Clopidogrel (Plavix) reduces the rate of thrombosis in the rat tuck model for microvenous anastomosis.

OBJECTIVE: To evaluate the effect of clopidogrel on the rate of thrombosis in a rat model for venous microvascular failure. STUDY DESIGN AND SETTING: Forty rats were treated with clopidogrel or saline control via gastric gavage in a randomized, blinded fashion. After allowing for absorption and activation, each femoral vein was isolated and a venous "tuck" procedure was performed. The bleeding time and vessel patency were subsequently evaluated. RESULTS: The rate of vessel thrombosis was decreased in the clopidogrel-treated group compared to controls (7.9% vs 31.4%, P < 0.025). The bleeding time was longer in the clopidogrel-treated group compared to controls (250 +/- 100 seconds vs 173 +/- 59 seconds, P < 0.015). CONCLUSION: Clopidogrel decreased the rate of thrombosis in the rat model for venous microvascular failure. SIGNIFICANCE: The use of clopidogrel may reduce the rate of venous thrombosis after free tissue transfer and may be indicated in select patients.     

Experimental evaluation of small intestinal submucosa as a microvascular graft material

The evaluation of porcine small intestine submucosa (SIS) in a microsurgical model was conducted using an interpositional graft in the rat femoral artery. The SIS grafts were fabricated from processed porcine material that was wrapped around a glass tube and oversewn longitudinally to produce a tubular structure. Of the 42 animals studied, 7 received grafts of untreated SIS (group I), 7 of the grafts were presoaked (PSH) in heparin (Group II), 7 animals were treated with systemic heparin prior to implantation of PSH-SIS (group III), 7 animals received SIS grafts crosslinked to heparin (group IV), 7 animals received SIS grafts crosslinked to urokinase (group V), and 7 animals received untreated autologous epigastric vein grafts (group VI). Patency was assessed postoperatively and selected grafts were evaluated by histology. All SIS grafts failed to maintain patency beyond the first postoperative hour. Histologic examination of the thrombosed graft surfaces revealed a smooth luminal surface with a thick layer of attached fibrin and platelets with a central occluding thrombus. The thickness of the induced fibrin layer appears to narrow intraluminal space significantly at the microvascular level. While having excellent success at vessel diameters greater than 3 mm, and in a variety of nonporcine animal models without xenographic rejection, SIS in this model was thrombogenic despite a favorable surface morphology as demonstrated by SEM. Even with use of heparin and urokinase SIS graft thrombosis occurred. © 1994 Wiley-Liss, Inc.     

溶栓抗凝联合治疗对大鼠急性血栓后血管内膜的影响

目的:观察溶栓抗凝联合治疗对急性大鼠下腔静脉血栓形成后血管内膜的影响。方法:SD大鼠105只建立急性下腔静脉血栓模型后随机分为肝素治疗组（A组），尿激酶治疗组（B组），肝素加尿激酶联合治疗组（C组），各组35只；另30只为假手术组。各组给药后分别于血栓形成后第1，4，7，14，28天获取病变段血管，观察血栓的结构演变与机化、内膜增生程度，检测静脉壁平滑肌胶原沉积量，扫描电镜评估内皮细胞形态学变化。结果:A组内膜增生最严重。C组胶原染色面积百分比A，B组少（P<0.01）。7d时B，C组内皮损伤较A组轻（P<0. 05）。28 d时C组内皮损伤较A，B组轻（P<0. 05）。结论:肝素加尿激酶治疗大鼠急性下腔静脉血栓形成具有良好的近、中期效果，能有效地保护内皮层完整，减轻血管壁肌纤维增生。     

下肢深静脉血栓形成导管溶栓术后髂静脉病变支架治疗的前瞻性对照性研究

目的观察下肢深静脉血栓形成(DVT)导管接触性溶栓(CDT)术后髂静脉支架治疗髂静脉病变的疗效。方法本研究为单中心前瞻性随机对照研究。155例下肢DVT患者经CDT治疗后,髂静脉远端主干静脉完全通畅,髂静脉残留狭窄大于50%者中的74例患者随机分为对照组和实验组:实验组45例行髂静脉支架置入,对照组29例髂静脉未置入支架。观察指标:深静脉通畅率,CEAP分类法中临床分级(C)变化,静脉临床严重程度计分(VCSS)变化及生活质量调查表(CIVIQ)评分。结果术后患者均获得随访,随访时间6～24个月。行静脉造影或彩超检查,实验组40例,对照组27例,实验组与对照组的终点通畅率比较差异有统计学意义[87.5%(35/40)vs29.6%(8/27),P<0.05];实验组与对照组的1年累积通畅率比较差异有显著统计学意义(86.0%vs54.8%,P<0.01)。实验组及对照组的CEAP分类法中临床分级(C)术前术后差值比较差异有统计学意义(1.61±0.21vs0.69±0.23,P<0.01)。随访终点实验组及对照组VCSS术后两组差值比较差异有统计学意义(7.57±0.27vs6.56±0.23,P<0.01)。实验组及对照组CIVIQ调查表终点评分比较差异均有统计学意义(22.67±3.01vs39.34±6.66,P<0.01)。结论髂静脉支架对下肢DVT导管溶栓术后治疗髂静脉病变能够提高深静脉的通畅率,提高疗效,提高生活质量。     

A Comparison of Two Surgical Techniques for the Second Stage of Brachiobasilic Arteriovenous Fistula Creation

Two‐stage transposed brachiobasilic arteriovenous fistula is a common procedure after brachiobasilic fistula (BBF) creation. Different techniques can be used for basilic vein transposition but few comparative literature reports are available. The aim of our study was to compare two different techniques for basilic vein transposition. The first maintains the BBF anastomosis and the basilic vein is placed in a subcutaneous pocket (BBAVF). The second transects the basilic vein at the BBF anastomosis and tunnels it superficially, with a new BBF in the brachial artery (BBAVFTn). From 2009 to 2014, all patients who underwent basilic vein superficialization were treated by one of the two techniques, recorded in a dedicated database and retrospectively reviewed. The surgeon chose the technique on the basis of personal preference. The two techniques were compared in terms of perioperative complications, length of hospital stay, time of cannulation, ease of cannulation, and long‐term patency. Eighty patients were included in the study: 40 (50%) BBAVF and 40 (50%) BBAVFTn. Length of hospital stay was similar in the two groups (median [interquartile range–IQR] 3(2) [BBAVF] vs. 2(1) [BBAVFTn], P = 0.52, respectively). BBAVFTn was associated with a lower hematoma incidence (1/40 [2.5%] vs. 15/40 [37.5%], P = 0.01), shorter first cannulation time (median IQR: 11(10) vs. 23(8) days, P = 0.01) and easier cannulation compared with BBAVF (32/40 [80%] vs. 15/40 [37.5%], P < 0.001). Median (IQR) follow‐up was 16(7) months. No statistical differences in terms of primary and assisted primary patency were found in BBAVFTn vs. BBAVF (at 24 months 91(5) vs. 71(7), P = 0.21 and 93(6) vs. 78(8), P = 0.33, respectively). Patients who underwent BBAVFTn surgery showed fewer surgical complications, better dialytic performance, and easier cannulation compared with those submitted to BBAVF.     

Preserved arterial grafts in microvascular surgery

The patency rates of arterial grafts preserved by immersion in 70% alcohol and arterial grafts preserved by ficin digestion and dialdehyde tanning were compared with the patency rate of fresh autogenous vein grafts in 5-mm defects in the femoral arteries of 50 rats. The overall patency rate for the fresh vein grafts was 90%. The patency rate at 2 weeks for the alcohol preserved arterial grafts was 40%; the patency rate for the dialdehydetanned arterial grafts at 2 weeks was 30%. The difference between the rates for the fresh vein grafts and the alcohol-preserved and dialdehyde-tanned grafts was statistically significant (P < 0.01 and P < 0.001, respectively). At 2 months there was no statistically significant difference in the rates between the autogenous vein grafts and the preserved arterial grafts, probably because of recanalization of grafts that had occluded primarily. From the data, it is concluded that fresh autogenous vein grafts are still superior to preserved arterial grafts in microvascular surgery.     

Adult liver transplantation and abnormalities of splanchnic veins: experience in 53 patients

The aim of this study was to analyze the influence of technical problems resulting from splanchnic venous anomalies on the outcome of orthotopic liver transplantation. From February 1984 until December 1995, 53 (16.3 %) of 326 adults underwent consecutive transplantations whilst having acquired anomalies of the splanchnic veins. These consisted of portal vein thrombosis (n = 32, 9.8 %), thrombosis with inflammatory venous changes (phlebitis; n = 6, 1.8 %) and alterations related to portal hypertension surgery (n = 15, 4.6 %). Because of major changes in surgical technique, i. e., eversion instead of blind venous thrombectomy, immediate superior mesenteric vein approach in cases of extended thrombosis, and piggyback implantation with preservation instead of removal of the inferior vena cava, patients were divided into two groups: those who underwent transplantation during the period February 1984 to December 1990 (group 1) and those transplanted between January 1991 and December 1995 (group 2). Surgical procedures to overcome the anomalies consisted of venous thrombectomy (n = 26), implantation of the donor portal vein at the splenomesenteric confluence (n = 5) or onto a splenic (n = 1) or ileal varix (n = 1), interposition of a free iliac venous graft between recipient superior mesenteric vein and donor portal vein (n = 9,) and interruption of surgical portosystemic shunt (n = 13). All patients had a complete follow-up. The 1- and 5-year actuarial patient survival rates were similar in patients with (n = 53) and without (n = 273) splanchnic venous abnormalities (75.5 % vs 78.1 % and 64.3 % vs 66.9 %, respectively). Early ( < 3 months) post-transplant mortality was 24.5 % (13/53 patients). Mortality was highest in the portal vein thrombophlebitis group (5/6, 83.3 %), followed by the portal hypertension surgery group (5/15, 33.3 %) and the portal vein thrombosis group (3/32, 9.4 %). Technical modifications significantly reduced mortality in group 2 (10.3 %, 3/29 vs 41.7 %, 10/24 patients in group 1; P < 0.05) as well as the need for re-exploration for bleeding (13.8 %, 4/29 patients in group 2 vs 15/24, 62.5 % in group 1; P < 0.01). Mortality directly related to bleeding was also significantly lowered (1/29, 3.4 % in group 2 vs 9/24, 37.5 % in group 1; P < 0.01). We conclude that liver transplantation can be safely performed in the presence of splanchnic vein thrombosis and previous portal hypertension surgery. Received: 11 April 1996 Received after revision: 31 July 1996 Accepted: 23 September 1996     

Deep vein thrombosis after total hip arthroplasty in Korean patients and D-dimer as a screening tool

Introduction  This prospective study was designed to confirm risk factors and to assess the incidence of deep vein thrombosis after total hip and surface replacement arthroplasty in Korean patients not receiving anticoagulation prophylaxis and to determine efficacy of plasma D-dimer levels as a screening test. Materials and methods  From May 2003 to August 2004, 221 consecutive patients undergoing unilateral total hip arthroplasty and hip resurfacing were evaluated. All patients underwent ultrasonography preoperatively and venography and/or ultrasonography on postoperative day 7. Plasma D-dimer levels were estimated by latex immuno-assay preoperatively and on days 3 and 7 postoperatively. Results  Of the 221 patients in our cohort, 23 developed deep vein thrombosis (10.4%). Age (r = 0.245, P < 0.001) and gender (r = 0.155, P = 0.021) significantly correlated with deep vein thrombosis. Rise in incidence paralleled increase in age (X² = 32.860, P < 0.001). D-dimer levels on postoperative days 3 (γ = 0.364, P < 0.001) and 7 (γ = 0.470, P < 0.001) were significantly correlated to the development of DVT. Conclusion  While incidence of deep vein thrombosis in Korean population after THA was lower than that in the West; it increased with age, and in female gender. Significant correlation was found between D-dimer levels and the development of deep vein thrombosis.     

Experimental study of the influence of arterial trauma on dependent distal tissue survival

An experimental model was developed combining arterial trauma with island flap creation using the rat groin flap system. Flap arteries were subjected to crush/avulsion injuries with subsequent microvascular repair. A second series involved resection 4 hr after thrombosis of injured flap arteries and interpositional vein grafting to reestablish circulation. A single bolus of systemic heparin was administered to half of the animals from each series on a blinded, randomized basis. Arterial patency at 7 days correlated with flap survival. There was no case of partial flap loss. Patencies improved in the first series from 31% to 71% with heparin administration (P less than 0.05) and from 58% to 90% in the second (not significantly different). A third series involving immediate resection of traumatized vessel and vein graft replacement achieved a patency of 92% (without heparinization). These results support the value of replacement of all traumatized arterial tissue with vein grafts and indicate the efficacy of systemic heparin (in single bolus) for enhancing the likelihood of maintaining patency. Furthermore, it is suggested that the occurrence of a thrombogenic site in the arterial inflow to a region of dependent tissue does not lead to partial tissue loss, and thus thromboembolic events may not be responsible for this clinical phenomenon.     

Synthetic,organic compound vepoloxamer (P-188) potentiates tissue plasminogen activator

Objective

Poloxamer-188 is a synthetic, organic compound that acts by binding hydrophobic pockets on damaged lipid bilayers in the circulation. P-188 reduces blood viscosity and confers anti-inflammatory and cytoprotective effects. Vepoloxamer (Mast Therapeutics, San Diego, Calif) is a purified version of this compound that has limited side effects. The aim of this study was to investigate drug interactions between vepoloxamer and heparin and tissue plasminogen activator (tPA).

Prevention of deep vein thrombosis with low molecular-weight heparin in patients undergoing total hip replacement

Summary In a double-blind, randomized multicentre trial, the efficacy and safety of two regimens for the prevention of postoperative venous thrombo-embolism, low-molecular-weight heparin (LMWH) CY 216 and unfractionated heparin (UH), were compared in 341 patients undergoing elective total hip replacement. A group of 169 patients received one subcutaneous injection of 48 mg ( 10 000 anti-Xa IC units) LMWH and two placebo injections per day and 172 patients received a fixed dose of 5000 IU UH t.i.d. Deep vein thrombosis was assessed by bilateral phlebography on day 14 ± 1 after surgery. Phlebography was successfully performed in 136 patients in the LMWH group and 137 patients in the UH group. Deep vein thrombosis occurred in 45 of 137 patients (33.1%) treated with LMWH CY 216 and in 47 of 136 patients (34.3%) who received UH. Pulmonary embolism occurred in 2 of 167 evaluable patients (1.2%) in the LMWH group and in 6 of 168 patients (3.6%) in the UH group. In addition, the incidence of proximal deep vein thrombosis was evaluated and was found to be 10.3% (14/137 patients) in the LMWH group and 19% (26/136 patients) in the UH group (P = 0.044, two-sided). The safety of the treatments, as assessed by the incidence of major haemorrhage, intra- and postoperative blood loss, transfusion requirements, haemoglobin drop and frequency of wound haematomata, was similar in the two groups. It is concluded that prophylaxis of postoperative thrombo-embolism in hip surgery with one subcutaneous injection (48 mg) of LMWH CY 216 is as effective and as safe as prevention with fixed low-dose heparin (5000 IU t.i.d). A tendency to reduced rates of pulmonary embolism (3.6% vs. 1.2%) and proximal deep vein thrombosis (19% vs. 10.3%) was observed in favour of LMWH CY 216.A list of authors is given in the Appendix to this paper     

Impact of inflow reconstruction on infrainguinal bypass

Purpose: This study assessed whether multisegmental disease that is severe enough to require an inflow procedure adversely affects infrainguinal bypass patency, limb salvage, or patient survival rates. Methods: The records of 495 patients who underwent 551 infrainguinal bypass grafting procedures were reviewed. Saphenous vein and prosthetic grafts were evaluated separately. Graft patency rates, patient limb salvage rates, and patient survival rates in those grafts that arose from a reconstructed inflow source were compared with those that arose from normal, nonreconstructed inflow sources. When grafts had either hemodynamic failure or occlusion, the cause of failure was identified. Results: Four-year primary patency rates in vein grafts that arose from a reconstructed inflow sources were lower than those in grafts that arose from nonreconstructed inflow sources (41% vs 54%; p = 0.006). Assisted primary patency rates and secondary patency rates, however, were similar (62% vs 74% and 64% vs 77%, respectively). The 4-year primary patency rate (45% vs 55%), assisted primary patency rate (60% vs 60%), and secondary patency rate (60% vs 61%) in prosthetic grafts did not vary based on inflow source. The most common cause of graft failure was inflow failure, except in the vein grafts that did not require an inflow procedure, in which the most common cause of failure was graft failure. Inflow failure occurred in 24% and 22% of the vein and prosthetic grafts with multisegmental disease, respectively, but in only 7% (p < 0.001) and 10% (p < 0.05), respectively, of those that arose from normal nonreconstructed inflow. The presence of an inflow procedure did not affect limb salvage rates or patient survival rates, regardless of graft material. Conclusions: Long-term patency rates, patient limb salvage rates, and survival rates in patients with a reconstructed inflow source were similar to those of patients with a normal nonreconstructed inflow. A major cause of occlusion is inflow failure, and this occurs in a greater proportion of patients with multisegmental disease. These patients, in particular, may benefit from patient surveillance to screen for progression of their inflow disease and to allow for intervention before infrainguinal graft occlusion. (J Vasc Surg 1997;26:928-38.)     

Improved microvessel repair: laser welding with an anti-thrombotic solder

BACKGROUND AND OBJECTIVES: Concentrated protein solutions can be used as thermally polymerized solders in laser welding. Solders supplemented with biologically active chemicals may provide in situ drug delivery for localized therapeutics. These studies characterize a serum albumin (SA) solder containing heparin, designed to reduce microvascular thrombosis rates. STUDY DESIGN/MATERIALS AND METHODS: Samples of heparin added to 30% SA to obtain heparin-to-albumin molar ratios (HAMR) of 4:1 and 2:1 were thermally polymerized, and heparin release into saline was measured. Using a rat thrombosis model, patency was determined for suture, and 0 U/ml (control), 2.5 U/ml, 50 U/ml heparin solder repairs. RESULTS: Heparin release was five times higher for 4:1 than 2:1 HAMR solder acutely, but was equivalent after 2 days. Animal patency rates were: 50% suture, 0% control, 50% low heparin, 66% high heparin (P < 0.05 vs. control). CONCLUSIONS: Solders incorporating heparin should provide in situ anti-thrombotic therapy reducing the risk of microvascular thromboses.     

Comparison of arterial and venous patency in a rat model of subendothelium-stimulated thrombosis

The effectiveness of anticoagulants and platelet aggregation inhibitors was compared using comparable rat models of arterial and venous thrombosis. A mechanical endothelium-denuding injury was created on the lumenal surface of donor Lewis rat carotid arteries. These were cut into 4–5 mm lengths and grafted into femoral veins and arteries of recipient syngeneic rats using microvascular anastomotic techniques. Recipients received either systemic heparin, or aspirin with dipyridamole, or saline (control). In the arteries, the 1-day patency rate was 94% in the heparin-treated rats, but only 50% in the aspirin/dipyridamole group and 44% in the control group. The venous patency rate was 56% in the heparin group, 31% in the aspirin/dipyridamole group, and 0% in the control group. This unique model for comparing thrombosis in arteries and veins shows that anticoagulation is more effective than inhibition of platelet aggregation in the rat arterial system, with less of a differential effect in the venous system. © 1997 Wiley-Liss, Inc. MICROSURGERY 17:226–229 1996     

Usefulness of 16-Row Multidetector Computed Tomography With Volume Rendering and Maximum Intensity Projection Reconstruction as a Monitor Pancreatic Graft Vessel Patency During the Early Postoperative Period

Thrombosis of the pancreatic graft vessels is the most common complication after transplantation. It leads to loss of 5% to 8% of grafts during the early postoperative period. The aims of this study were to evaluate the usefulness of 16-row multidetector computed tomography (16-MDCT) with volume rendering (VR) and maximum intensity projection (MIP) reconstruction to monitor pancreatic graft vessel patency during the early postoperative period and the efficacy of a heparin infusion as a treatment for graft thrombosis. Among 40 consecutive simultaneous pancreas-kidney transplant recipients, 16-MDCT was performed at 6 to 8 days after the operation. Secondary reconstructions were obtained with VR and MIP algorithms to evaluate the morphology and patency of the extra- and intrapancreatic arteries and veins. In cases of thrombosis, every patient was treated with an infusion of unfractionated heparin. In 15 recipients, thrombosis of the large vessels was detected by 16-MDCT. Heparin infusions saved five pancreatic grafts (5/15; 33.3%), but the other 10 pancreatic grafts were removed. In another four recipients (4/40; 10%) the thrombi were localized only in small intrapancreatic vessels. Treatment with heparin infusion was successful in 3/4 (75%) cases with patent vessels upon control computed tomography examination. We compared the efficacy of heparin treatment depending on the diameter of the thrombosed vessel, observing a significant difference (5/15 vs 3/4; P < .01; chi-square). 16-MDCT with secondary reconstruction by application of VR and MIP algorithms was an efficient method to visualize not only large pancreatic graft arteries and veins but also intrapancreatic parenchymal vessels. In cases of thrombosis of small intrapancreatic vessels, unfractionated heparin infusion significantly decreased graft loss.