Studies of the antithrombotic effects of dextran 40 following microarterial trauma.

The effects of dextran 40 on platelet function and thrombus formation have been studied in vivo in arteries of the rabbit ear. Intra-aortic infusions of 32P-labelled platelets were followed by infusions of 1.7 g dextran 40 in 17 ml saline/kg b w. Treated and untreated groups were studied using as trauma either end-to-end anastomosis or arteriotomy (7 mm)/intimectomy (5 mm). After restoring blood flow, bleeding times at the sites of anastomosis and arteriotomy/intimectomy were recorded. Accumulations of labelled platelets were followed in vivo for 2 hours, after which patencies were determined and amounts of red thrombotic material evaluated. In a separate series of measurements, haematocrit levels after dextran infusion were studied. Nearly all vessels in the end-to-end anastomosis groups were patent. In the arteriotomy/intimectomy groups, there was a significant increase in patency following dextran infusion. Dextran infusion did not alter platelet accumulation following end-to-end anastomosis, but following arteriotomy/intimectomy median values were somewhat reduced. Its antithrombotic effects must therefore arise mainly at stages of thrombus formation subsequent to platelet deposition.     

Time of low-dose acetylsalicylic acid administration influences in vivo platelet function and thrombus formation following arteriotomy and intimectomy; an experimental study in small arteries of rabbits

To investigate if low-dose acetylsalicylic acid (ASA), 4 mg/kg b.w., infused peroperatively or 10 hours preoperatively has antithrombotic effects, the central arteries of rabbit ears were prepared and 32P-labeled platelets injected. Arteriotomy and intimectomy were performed and blood flow was restored. Bleeding times at the sites of arteriotomy/intimectomy, in vivo accumulations of isotope-labeled platelets, amounts of red thrombotic material, and patency were recorded. Bleeding times following arterial puncture and the effect of ASA on thromboxane production were studied separately. Ten hours after ASA administration, bleeding times were shortened at the sites of arteriotomy/intimectomy but were prolonged following arterial puncture. Platelet accumulations were lower in patent vessels in this group than in an untreated control group. Peroperative ASA treatment increased but treatment 10 hours prior to blood flow restoration did not significantly affect the number of occlusions. Thromboxane production in ASA-treated rabbits is largely inhibited even 14 hours after administration.     

The nature of arterial healing following dextran treatment of experimental small artery trauma.

Vascular thrombosis is a major cause of morbidity and death. Because of the many variables involved with thrombosis in patients, major advances in treatment often depend upon design and study of adequate experimental models which provide a degree of control of the variables. Arterial trauma was produced in small femoral arteries 3 mm. or less in diameter by a standardized intimectomy technique. One group of animals was treated with an equal volume of saline and served as controls. Serial sections of blood vessels at graded time intervals from one hour to 90 days were studied. The damaged blood vessels of dextran-treated animals did not thrombose and provided an opportunity for studying the mechanism of healing in traumatized blood vessels which remained patent. The damaged blood vessels of saline-treated animals uniformly thrombosed and eventually healed for scar formation with evidences of attempts at recanalization. The blood vessels of dextran-treated animals remained open for as long as 90 days and were re-endothelialized and healed. What appears to be beginning re-endothelialization of blood vessels of dextran-treated animals was observed as early as 48 hours. In a model experimental setting, dextran has been shown to prevent thrombosis and permit healing in small arteries subjected to a standardized surgical trauma.     

Adverse effects of topical prostacyclin application in microvascular surgery: an experimental study

The efficacy of topical prostacyclin as an antithrombotic agent was tested in a model of microvascular trauma. Preliminary measurements were made to determine a suitable dosage. Twenty-seven central arteries of rabbit ears were then prepared and 32P-labelled platelets infused intraaortically. Arteriotomy (7 mm) was followed by intimectomy (5 mm). Fifteen vessels in a control group were irrigated with Ringer's lactate and 12 vessels in an experimental group were treated with prostacyclin (10 ng/ml) in normal saline. Bleeding times at the sites of arteriotomy intimectomy, in vivo accumulations of isotope-labelled platelets, amounts of red thrombotic material, and patency were recorded. Patency was lower following prostacyclin treatment (1/12 as against 5/15) but not significantly so, and there were no statistically significant differences in other parameters. Prostacyclin treatment decreased vessel wall tone, interfering with blood-flow and promoting thrombus formation.     

Influence of early fibrinolysis inhibition on thrombus formation following microvascular trauma

The effect of the fibrinolysis inhibitor tranexamic acid on early thrombus formation following microvascular trauma was investigated in the central arteries of ears in 86 rabbits (in all 172 vessels), divided into four separate blind randomised studies. In the first part a common end-to-end anastomosis was done and in the last three studies a severe trauma-arteriotomy/intimectomy was performed. Parameters studied were vessel bleeding times, patency rates, weights of intraluminal thrombotic material, haematocrit and plasma fibrinolytic activity. In the first study consisting of 14 control animals and 18 animals treated with 14 mg/kg bw of tranexamic acid, end-to-end anastomosis was performed on the central artery of one ear and on the central vein of the other ear. In the second, third, and fourth studies consisting of 18, 20, and 16 control vessels and the same number of corresponding vessels in treated animals a 7-mm longitudinal arteriotomy followed by a deep 5-mm-long intimectomy was performed. The second and third treated groups were given 14 mg/kg bw of tranexamic acid 5 min and 1 h, respectively, before reflow and the fourth group 28 mg/kg bw 5 min before reflow. The difference between the second and third studies was the addition, to mimic clinical situations, of 8.5 ml saline/kg bw 2 h before reflow in the third study. In conclusion, treatment with a single clinical dose, 14 mg/kg of tranexamic acid, did not influence vessel bleeding times or thrombus formation in the anastomotic or severe trauma models and seems safe to use. Not even a double clinical dose, 28 mg/kg, influenced thrombus formation in a statistically significant way. © 1997 Wiley-Liss, Inc. MICROSURGERY 17:278–285 1996     

Dextran's antithrombotic properties in small arteries are not altered by low-molecular-weight heparin or the fibrinolytic inhibitor tranexamic acid: An experimental study

In two separate blind, randomized studies, 48 rabbits were divided into five groups. Three treated groups received dextran 70 (0.51 g/kg) as a single injection, dextran 70 combined with low molecular-weight heparin (LMWH) (560 IU/kg as anti-FXa and 140 IU/kg as APTT in 3 hr), and dextran 70 plus tranexamic acid (14 mg/kg) following severe arterial trauma (arteriotomylintimectomy). Two control groups received the same amount of saline. The bleeding times from the arteriotomy were recorded, and patency rates and the weight of thrombotic materials were registered 2 hr after reperfusion of the trauma region. The bleeding times in three treated groups, all including dextran, were significantly prolonged compared to the control groups (P < 0.05 or 0.01). The patency rates of treated groups, which were 100% (1 8/18 vessels patent) in the dextran-treated group, 90% (18/20 vessels patent) in the dextran + LMWH group and 95% 19/20 vessels patent) in dextran + tranexamic acid group, were significantly higher than those of their control groups (55-67% patent vessels) (p < 0.05 or 0.01). The mean weights of thrombotic materials were significantly reduced in the treated groups compared to the corresponding control groups (p < 0.01). In conclusion, dextran 70 in an ordinary dose exerted such a profound antithrombotic effect (100% patency) in small traumatized arteries that the addiiion of a high dose of LMWH could not further improve patency rates or decrease thrombotic materials but did not prolong vessel bleeding times compared to the single dextran treatment. The addition to dextran 70 treatment of a clinical dose of the antifibrinolytic agent tranexamic acid did not disturb the good antithrombotic effect, suggesting that fibrinolysis enhancement is a less important characteristic of the dextran antithrombotic effect in small traumatized arteries. © 1993 Wiley-Liss Inc.     

Importance of fibrinolysis in limiting thrombus formation following severe microarterial trauma: an experimental study in the rabbit.

In a blind randomized study, two groups of six rabbits were treated with either the fibrinolytic inhibitor tranexamic acid, 14 mg/kg bw, or isotonic saline solution (control group) given intraaortically as single bolus injections 5 min prior to arteriotomy and intimectomy of central ear arteries. Arteriotomic bleeding times, accumulations of 32P-labeled platelets, patency, and sizes of thrombus deposits 2 hr after reperfusion were recorded. Fixed vessels were observed by scanning electron microscopy. Bleeding times were similar in the two groups. The patency rate in the tranexamic acid group was 2/12, i.e., a significant reduction (P less than 0.05) from 7/12 in the control group. Thrombus deposits in occluded vessels contained large amounts of fibrin and red cells. Platelet accumulations in occluded vessels were significantly lower in the tranexamic acid group than in the control group, which indicates that the ratio of fibrin to platelets was increased in thrombi formed during antifibrinolytic treatment. This study has demonstrated the importance of normal fibrinolytic capacity in limiting thrombus formation following microarterial trauma. It is suggested that the use of antifibrinolytic agents in microvascular surgery should be restricted.     

The strength of microvascular anastomoses— an experimental evaluation in rats

To determine the longitudinal strength of microvascular anastomoses during early healing, the left femoral arteries of 56 rats were divided and anastomosed with six interrupted sutures of 10– 0 nylon. The right femoral arteries served as unoperated controls. The vessels were then harvested immediately, or 3, 7, 14, 21, 28, or 120– 150 days after surgery. The crosssectional surface area was measured and the force required to pull the vessels apart (burst strength) was determined with a tensiometer. Fifty- four of the 56 anastomosed vessels were patent at the time of harvest. All of the operated vessels ruptured at the site of anastomosis when the sutures pulled through the vessel wall. The mean burst strength of the anastomosed vessels was 44% of the contralateral unoperated controls immediately after surgery and did not significantly increase for four to five months. It was concluded that early mobilization of replanted parts is not limited by the strength of microarterial anastomoses.     

Angiographic assessment of graft patency after coronary endarterectomy

Fifty-one consecutive patients underwent 68 manual core endarterectomies between April 1985 and May 1987. There were 42 men and nine women, mean age 60 years (range 39 to 81). All patients underwent coronary bypass grafting alone. There were no reoperations. There was one operative death (2%). Forty patients consented to early (mean 19 days) and 27 to late (mean 19 months) repeat angiography. At the early restudy 47 of 52 (90%) grafts to endarterectomized vessels were patent. This rate fell to 27 of 42 (64%) at late restudy. There was considerable variation in the angiographic appearance of the endarterectomized vessels, ranging from a large caliber, smooth walled vessel to an attenuated vessel with irregular walls. In general, there was a tendency toward "shrinkage" of these vessels by the late restudy, suggesting fibrosis in the walls. We conclude that, although endarterectomy can be done on most atheromatous vessels with excellent early graft patency, these vessels tend to show an accelerated deterioration with time, resulting in a low late patency rate. We suggest that the procedure be reserved for vessels that are truly inoperable by other means and only for vessels that supply a coronary bed of at least moderate size.     

Complete patency in thrombus-occluded arteries two weeks after laser recanalization

The potential problem of rethrombosis after laser recanalization was studied in 16 thrombus-occluded canine femoral arteries. Balloon de-endothelialization and thrombin-human blood injection produced adherent, completely occlusive thrombi 4.13 +/- 1.54 cm in length; laser exposure of the thrombi occurred at 18.35 +/- 22.1 hours. The argon laser catheter was introduced via a proximal arteriotomy and a power of 3.83 +/- 0.58 W delivered for 411.3 +/- 296.87 seconds. Follow-up period was 14 days. All arteries were patent immediately after and 14 days following lasing, as demonstrated by angiography. There was no vessel perforation. Seven of the dogs were maintained on aspirin and dipyridamole 4 days before and throughout the study, but there were no differences in thrombus length, laser power, or duration of laser exposure between these dogs and those receiving no anti-platelet therapy. Control thrombosed arteries (without laser energy application) showed no autolysis within 14 days in all dogs and up to 95 days in three dogs followed for this period of time. These data show that rethrombosis of totally occluded, thrombosed arteries is not present up to 2 weeks later after laser recanalization, with or without the aid of anti-platelet therapy.     

Time-dependent effects of low-level laser therapy on the morphology and oxidative response in the skin wound healing in rats

This study aims to investigate the effect of different energy densities provided by low-level laser therapy (LLLT) on the morphology of scar tissue and the oxidative response in the healing of secondary intention skin wounds in rats. Twenty-four male adult Wistar rats were used. Skin wounds were made on the backs of the animals, which were randomized into three groups of eight animals each as follows, 0.9% saline (control); laser GaAsAl 30 J/cm² (L30); laser GaAsAl 90 J/cm² (L90). The experiment lasted 21 days. Every 7 days, the wound contraction index (WCI) was calculated and tissue from different wounds was removed to assess the proportion of cells and blood vessels, collagen maturation index (CMI), thiobarbituric acid reactive substance (TBARS) levels and catalase activity (CAT). On the 7th and 14th days, the WCI and the proportion of cells were significantly higher in groups L30 and L90 compared to the control (p?<?0.05). At all the time points analyzed, there was a greater proportion of blood vessels and a higher CMI in group L90 compared to the other groups (p?<?0.05). On the 7th and 14th days, lower TBARS levels and increased CAT activity were found in the L90 group compared to the control (p?<?0.05). On the 7th day, a moderately negative correlation was found between TBARS levels and WCI, CMI and CAT in all the groups. LLLT may modulate the oxidative status of wounded tissue, constituting a possible mechanism through which the LLLT exerts its effects in the initial phases of tissue repair.     

Heat-induced tissue fusion for microvascular anastomosis

Laser tissue welding was compared with a crude method of bipolar coagulator-generated heat application for achieving the same heat-induced welding effect in rat microarterial anastomoses. Rat femoral arteries were anastomosed with three triangulated stay sutures and subsequent laser welding or bipolar coagulator application between each pair of stitches. Control (non-welded) vessels received nine stitches placed circumferentially. Laser-welded vessel patency at 1 or more days postoperatively was 90% (65/72) for vessels treated with 0.1-second laser pulses, not significantly different from controls (100%; 16/16) or coagulator-welded anastomoses (88%; 14/16). Pseudoaneurysm rates were higher in the welded vessels (9% and 14% for laser- and coagulator-treated vessels, respectively) than in controls (0%). Histologic and electron microscopic evaluation revealed good healing with no apparent differences between laser- and coagulator-welded repairs. These findings suggest that laser application for microvascular tissue welding is similar to poorly controlled welding with a bipolar coagulator. © 1997 Wiley-Liss, Inc. MICROSURGERY 17:198–208 1996     

创伤继发臂丛神经急性卡压征

目的　总结创伤继发臂丛神经急性卡压征的病因、症状与体征、治疗及预后。方法　 12例因创伤引起肩锁区肿胀、瘀血、压痛、畸形外 ,肩锁区存在搏动感及血管杂音 ;臂丛下干支配区感觉及 /或功能障碍。伴肋骨、锁骨、多处骨折 7例 ;锁骨下血管损伤 (破裂、假性动脉瘤、动静脉瘘 ) 9例 ,血肿 3例。诊断为创伤继发臂丛神经急性卡压征。采用假性动脉瘤切除动脉直接缝合或静脉移植 3例 ,血管吻合、修补术 4例 ,血管结扎 2例 ,血肿去除 3例。骨折切开复位内固定 8例 ,臂丛神经松解术 12例。结果　 12例术后平均随访 2 6个月 ,患侧的桡动脉搏动良好 ,肩胛带骨折已骨性愈合。臂丛神经功能恢复按中华医学会手外科学会上肢部分功能评定试用标准评定[1] :优 11例 ,可 1例。结论　创伤继发臂丛神经急性卡压的病例起病急 ,在伤后 2～ 3h或 1～ 2d内发生。除有臂丛神经损伤症状外 ,还伴有肩胛带骨折及锁骨下血管损伤。早期手术预后较好。     

Influence of vein-patch angioplasty on carotid endarterectomy healing

We studied the influence of venous patching on the patency, endothelial regeneration, and wall healing of endarterectomized carotid arteries in a canine model. Thirteen dogs underwent bilateral common carotid endarterectomies (intimectomy and partial media excision). In each dog, one artery was closed by continuous suture and the contralateral artery was closed by external jugular vein-patch angioplasty; arteries were excised at two postoperative intervals (two to three and four to five weeks) for light, scanning, and transmission electron microscopy. The patency of arteries closed primarily (9/13 [69%]) was not significantly different compared with arteries closed with venous patches (12/13 [92%]). By scanning electron microscopy, regeneration of the endothelial monolayer occurred by migration from the endarterectomy end points and suture lines. Despite survival of the vein-patch endothelium, the rate and pattern of reendothelialization was not altered by venous patching. In both patched and unpatched vessels, endothelial regeneration was incomplete at two to three weeks and completed by four to five weeks. The histologic characteristics of the endarterectomized arterial wall after operation were also not influenced by the closure technique. In contrast with the healing artery wall, vein-patch walls did not develop a thickened intima. Although venous patching does not influence early patency, endothelial regeneration, or wall healing after endarterectomy, vein-patch angioplasty does increase vessel diameter and prevents the development of circumferential intimal thickening, attributes that are beneficial in minimizing restenosis.     

Effect of low and ultra low oral doses of acetylsalicylic acid in microvascular surgery. An experimental study in the rabbit.

About 10 h after administering acetylsalicylic acid (ASA) orally in doses of 4 mg and 20 micrograms/kg b.w., the central arteries of rabbit ears were subjected to severe vascular trauma (arteriotomy/intimectomy). Bleeding times from the trauma regions at reperfusion were measured and the activities from accumulating 32P-labelled homologous platelets recorded until 2 h after reperfusion when patencies were determined. In other studies, the effects of ASA on ex vivo platelet aggregation (aggregometry), thromboxane production, euglobulin clot lysis time and bleeding time following arterial puncture were investigated. Relative to controls, the following parameters were changed: patency was increased, as were the bleeding times following arterial puncture and thromboxane production was reduced. The median values of platelet accumulation were lower, but the changes were not statistically significant. Aggregometry showed decreased rates of platelet aggregability following treatment with ASA 4 mg/kg.     

Removal of surgically induced fibrous arterial plaques by argon ion laser angiosurgery using a multifiber delivery system. An experimental study in the dog

Removal of intravascular atherosclerotic obstructions by laser irradiation has gained the attention of many investigators, but has proven to be considerably more difficult to accomplish than initially envisioned. We tested, in an animal model, an argon ion laser delivery system that permits control of (1) laser power, (2) exposure time, and (3) laser beam spot size. The study was conducted on surgically, induced focal fibrous plaques in the carotid arteries of nine dogs. Plaque removal, vessel patency, and healing were evaluated angiographically and by light and electron microscopy at intervals up to 60 days after treatment. Results showed that intravascular obstructions could be removed, healing occurred, and vessels remained patent for up to 60 days.     

Laser-assisted microsurgical anastomosis

A low power carbon dioxide laser was used to perform 212 end-to-end laser-assisted microvascular anastomoses (LAMA) of femoral arteries (mean diameter, 1.2 mm) in Sprague-Dawley rats. Eighty-two conventional microvascular suture anastomoses (CMSA) utilizing 10-0 monofilament interrupted sutures were done for comparison of techniques and wound healing. The mean duration of each anastomosis procedure was 16 minutes for the LAMA repairs, compared to an average of 27 minutes for the CMSA repairs (P less than 0.05). All anastomoses were patent at the completion of the procedure. Each laser-assisted anastomosis required an average of seven intermittent laser exposures of 0.1 to 0.3 seconds each with approximately 80 mW of CO2 (wavelength = 10.6 micron) radiation at a spot size of 150 micron. A patency rate of 95% was obtained on the LAMA vessels (202 of 212) compared to 96% for the CMSA repairs (79 of 82). A total of 14 aneurysms were noted in the LAMA group (7%) compared to 11 in the CMSA (13%). All aneurysms were in patent vessels. Histological analysis indicates that the progression of wound healing of LAMA and CMSA anastomoses follows similar paths chronologically and morphologically with increased scar tissue formation around the suture. Scanning electron microscopy confirms the comparable luminal healing of the LAMA and CMSA vessels, with complete reendothelialization occurring by 3 weeks postoperatively. The tensile strength of the LAMA repair, although low immediately after operation, is comparable to that of the intact artery at 21 days. These findings suggest that a low energy carbon dioxide microsurgical laser has potential beneficial clinical application for anastomosis of small vessels.     

Differential regulation of blood vessel formation between standard and delayed bone healing

Blood vessel formation is a prerequisite for bone healing. In this study, we tested the hypothesis that a delay in bone healing is associated with an altered regulation of blood vessel formation. A tibial osteotomy was performed in two groups of sheep and stabilized with either a rigid external fixator leading to standard healing or with a highly rotationally unstable one leading to delayed healing. At days 4, 7, 9, 11, 14, 21, and 42 after surgery, total RNA was extracted from the callus. Gene expressions of vWF, an endothelial cell marker, and of several molecules related to blood vessel formation were studied by qPCR. Furthermore, histology was performed on fracture hematoma and callus sections. Histologically, the first blood vessels were detected at day 7 in both groups. mRNA expression levels of vWF, Ang1, Ang2, VEGF, CYR61, FGF2, MMP2, and TIMP1 were distinctly lower in the delayed compared to the standard healing group at several time points. Based on differential expression patterns, days 7 and 21 postoperatively were revealed to be essential time points for vascularization of the ovine fracture callus. This work demonstrates for the first time a differential regulation of blood vessel formation between standard and mechanically induced delayed healing in a sheep osteotomy model. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res     

外源性bFGF对深Ⅱ度烫伤大鼠创面血管内皮细胞增殖与迁移的影响

目的观察大鼠深Ⅱ度烫伤创面敷用bFGF后肉芽组织中血管增殖与迁移情况,以及相关信号蛋白的表达情况.方法 Wistar大鼠133只随机分为正常对照A组(n=7)、单纯烫伤B组(n=42)、bFGF治疗C组(n=42)、c-fos抗体D组(n=42).利用大鼠30%深Ⅱ度烫伤模型,于伤后3、6小时,1、3、7、 14和21天取创面皮肤标本,运用免疫组织化学染色,检测真皮内血管形成的情况,原位杂交和免疫组织化学技术观察血管内皮细胞增殖细胞核抗原(proliferation cell nuclear antigen,PCNA)、黏着斑蛋白激酶(focal adhesion kinase,FAK)及c-fos的表达情况.免疫荧光手段观察细胞外信号调节激酶(extracellular signal-regulated kinase,ERK)在血管形成中的激活情况.结果 B、C组于伤后7天血管内皮细胞增殖明显,14天后FAK的表达也显著增加.损伤后3～6小时ERK的表达增强,随后1～3天,c-fos亦发生相对应的变化.各时间点D组血管内皮细胞PCNA和FAK的表达均减弱,肉芽组织中微血管的数量低于B组.敷用外源性的bFGF后,血管内皮细胞的增殖与前者变化不显著,但FAK的表达较A组增强明显,ERK的表达也显著增加,特别是c-fos也在伤后1～3天呈增强趋势.结论使用外源性bFGF通过ERK信号通路激活c-fos介导血管内皮细胞的迁移活性;肉芽组织中血管形成能力的增强有助于加速创面愈合进程.     

撕拉性离断血管损伤范围的实验观测

目的　测定撕拉性离断血管损伤的程度和范围。方法　大白兔 2 0只 ,随机分为切割性离断组 (A组 )和撕拉性离断组 (B组 )。以肉眼、手术显微镜、光镜和电镜测定每组动物血管损伤的程度和范围。分别于再植后3及 10天探查 ,统计通畅率并比较两组的愈合过程。结果　 A组血管断端平齐 ,三层壁损伤范围一致 ,于断端 1mm范围以上管壁基本正常。 B组损伤重 ,内皮细胞缺失 ,内弹力层呈“跳跃样”破坏。在手术显微镜下观察正常部位以外 2～ 3mm仍有损伤。结论　撕拉性离断的血管损伤不规则 ,范围广。清创时应在显微镜下观察正常的部位外再切除 2～ 3mm,以保证管壁的完整。