High accumulation of plasminogen and tissue plasminogen activator at the flow surface of mural fibrin in the human arterial system

PURPOSE: We assessed the fibrinolytic activity of the organized mural thrombus lining of aneurysms and prosthetic grafts. METHODS: Between May 1995 and April 1998, the full-thickness mural thrombi of aneurysms and the pseudointima lining of vascular grafts were obtained from 12 patients, ranging from 55 to 78 years in age, who underwent elective surgery. These included five aortic arch aneurysms, four abdominal aortic aneurysms, and three patent synthetic vascular grafts. The specimens were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)/immunoblot and immunohistochemistry for human plasmin/plasminogen, tissue plasminogen activator (tPA), and fibrin degradation product (D-dimer). RESULTS: In the SDS-PAGE/immunoblot, 25- and 27-kd bands appeared specifically in experimental fibrin plates after limited digestion by plasmin and were also recognized in the mural thrombi. The presence of bands at 25 and 27 kd, which were most prominent in sections near the flow surface layer, was consistent with the hypothesis that the mural fibrin was digested by the endogenous plasmin. Apparent immunoreactivity was found at the flow surface of the masses at a thickness of 10 to 400 micrometer suggesting the presence of a plasminogen and tPA-rich layer, with D-dimer as a consequential product of fibrinolysis. CONCLUSION: The hypothesis that fibrin surfaces in the arterial system acquire fibrinolytic activity because of digestion by circulating endogenous plasmin was confirmed; this may contribute to the antithrombogenicity of these flow surfaces.     

Laser angioplasty: an atherosclerotic swine model

Rapid production of occlusive, atherosclerotic iliac artery lesions was achieved in 25 of 27 (93%) Yucatan miniature swine, using a combination of high cholesterol diet and mechanical endothelial denudation. Animals were fed a diet with 2% of their calories as raw cholesterol 2 weeks prior to balloon denudation of iliac arteries, which resulted in atherosclerotic lesions within 8 weeks. Early after denudation we have demonstrated total occlusion of arteries by fibrin thrombi, which in time organize and ultimately result in fibrotic occlusive disease. The arterial walls and intima show varying degrees of foam cell infiltration with destruction of the internal elastic lamina and calcification. Totally occluded lesions show fibrointimal proliferation, fibrosis, and multiluminal channels, which are probably secondary to organized thrombus. Our model of occlusive iliac artery disease involving vessels of 1 to 3 mm in diameter allows the development of catheter systems suitable for use in human peripheral and coronary arteries. This model is useful for the study of angioplasty, whether mechanical, balloon, or laser-mediated.     

膜性梗阻型布-加综合征隔膜和机化血栓组织中相关细胞因子表达的研究

目的 通过对膜性梗阻型(membranous obstruction of the inferior vena cava,MOIVC or MOVC)布加综合征(Budd Chiari syndrome,BCS)隔膜和静脉机化血栓组织中相关细胞因子表达的研究,探讨MOVC的隔膜组织和机化血栓之间的相互关系.方法 运用免疫组织化学方法对11例MOVC的隔膜及8例DVT患者的机化血栓组织中转移生长因子β受体(TGFβR)、血小板衍化生长因子受体(PDGFR)、内皮素-1(ET-1)、第八因子相关抗原(FⅧ-rAg)、α1-抗胰蛋白酶(α1-antitrypsin)、铁蛋白(ferritin)的表达进行研究.结果 11例MOVC患者隔膜组织和8例DVT患者的机化血栓组织中细胞因子表达率分别为:TGFβR:72.3%和50%(P＞0.05),PDGFR:45.5%和100%(P＜0.05),ET-1:100%和0(P＜0.05),FⅧ-rAg:90.9%和12.5%(P＜0.05),ferritin:72.3%和100%(P＞0.05).α1-antitrypsin在隔膜和机化血栓组织中均未表达.结论 通过对MOVC型BCS隔膜及DVT机化血栓组织中相关细胞因子表达的研究,表明MOVC隔膜和机化血栓之间可能存在某种联系.     

Advantages of superior approach for mitral valve surgery

Technical factors in mitral valve surgery (MVS) which may influence neurological complications, trauma to the left atrium and formation of atrial mural thrombi have not previously been described in detail. We have reviewed the records of 146 patients (pts) undergoing MVS through the superior approach between January 1974 and May 1981. The series consisted of 97 females and 49 males with a mean age of 57 +/- 18 years. All but 4 pts were in New York Heart Association functional class III or IV. Twenty-five pts underwent open mitral commissurotomy, 116 had valve replacement and 5 had annuloplasty. Concomitant procedures were coronary bypass in 47, aortic valve replacement in 18 and resection of left ventricular aneurysm in 3. Left atrial thrombi were removed in 21 pts. Thirteen pts (9%) died postoperatively. The causes of death were left ventricular failure in 7, arrhythmia in 4 and atrio-ventricular disruption in 2. Two of these pts also had cerebral dysfunction. Autopsy examination in 8 pts failed to reveal formation of fresh left atrial septal or posterior mural thrombus. Postoperative complications included transient neurologic injury presumed to be due to air embolus in 3 and postoperative bleeding from atrial suture line in one. The mean follow-up for the survivors has been 30 months. There have been 16 (12%) late deaths from 1 to 72 months (mean 15). Autopsy examination of 4 pts and surgical exploration in one other pt which failed to reveal organized left atrial mural thrombus. Only one late death was related to prosthetic thrombosis. This occurred following cessation of anticoagulations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Decrease in fibrin content of venous thrombi in selectin-deficient mice

The purpose of this study was to quantify the fibrin content of thrombi produced in a mouse model of venous thrombosis and correlate this to thrombus mass. The role of P-selectin, E-selectin, and IL-10 on thrombus fibrin content was analyzed using knockout (KO) mice. Five groups of mice were evaluated: control (N = 10), P-selectin KO (N = 7), E-selectin KO (N = 5), combined E-/P-selectin KO (N = 12), and IL-10 KO (N = 10). Venous thrombosis was induced by ligation of the infrarenal IVC. Mice were sacrificed on postoperative days (POD) 2 and 6. Thrombus mass was calculated. Sections of IVC were stained with an antibody that cross reacts with mouse fibrin. The distribution of RGB color pixels was generated from digitized micrographs of the thrombus of each animal. The mean pixel value for each group was compiled and analyzed using 2-way ANOVA. Mean pixel value per group was correlated with the mean thrombus mass per group.Color analysis demonstrated significant decreases in the analyzed fibrin content on POD-2 between the control vs E-/P-selectin KO (P < 0.05) and control vs IL-10 KO (P < 0.05) groups. In addition, significantly less fibrin staining was noted on POD-6 between the control vs E-selectin KO (P = 0.03), control vs P-selectin KO (P = 0.01), and control vs E-/P-selectin KO (P < 0.01). There was a strong overall correlation between the mean pixel value for each group and the thrombus mass (R = 0.964; P < 0.01).This study demonstrates a difference in fibrin content of thrombi produced in animals deficient in E-selectin, P-selectin, and IL-10, supporting their importance in thrombus amplification, fibrin formation, and the mass of thrombus formed.     

Pathogenesis of mural thrombi in idiopathic cardiomyopathy]

Thirty-two hearts from patients with idiopathic cardiomyopathy were examined postmortem. A comparative morphological study of the human hearts and of hearts from cardiomyopathic hamsters, rabbits and baboons indicates that severe cardiac dilatation with intracavitary stasis and abnormal turbulent blood flow are the most important factors in the pathogenesis of mural thrombi in idiopathic cardiomyopathy.     

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.     

Is the Size of an Abdominal Aortic Aneurysm Associated with Coagulopathy?

Abdominal aortic aneurysm (AAA) volume and intraluminal thrombi were analyzed with respect to the number and function of platelets, blood cells, and coagulation factors. A group of 43 patients who underwent repair of an AAA were enrolled in this study. The maximum diameter and volume of the AAA, and the volume of intraluminal thrombi and lumen were measured by computed tomography with planimetry. The platelet count and platelet function, prothrombin time, activated partial thromboplastin time, fibrinogen, plasminogen, antithrombin 3, fibrin degradation products (FDP), D-dimer, and blood cell counts were measured. Spontaneous platelet aggregation and the FDP, and D-dimer levels were elevated; all other factors remained within the normal range. Intraluminal thrombus volume was strongly correlated with the volume and diameter of the AAA. However, no correlation was observed between the size of the AAA and coagulating factors, including the number and aggregation value of platelets. AAAs are frequently associated with a coagulating disorder. However, its size and thrombus volume are not correlated with coagulation changes. Although an intraluminal thrornbus increases along with fee enlargement of the AAA, the clinical manifestation of bleeding is rarely associated with an AAA. Therefore coagulopathy in patients with an AAA is not fully explained by its morphology.     

Inferior vena cava replacement: the role of antiplatelet therapy

To evaluate the effect of ibuprofen on early thrombus formation following inferior vena cava (IVC) replacement, a 4-cm segment of IVC was replaced with a 5-cm (10-mm-i.d.) segment of reinforced polytetrafluoroethylene (PTFE) graft in 12 dogs. Autologous platelets and canine fibrinogen were labeled with 111In and 125I, respectively, and injected into each animal 24 hr prior to vena cava replacement. Six dogs served as controls and six were treated with 12.5 mg/kg ibuprofen intravenously 1 hr preoperatively. All dogs were heparinized with 100 U/kg intravenous heparin prior to crossclamping the IVC: heparin was not reversed at the end of the procedure. Three hours after normal circulation was restored, the grafts were removed and counts of radioactivity made. All grafts were patent. The mean platelet count for the control group was 12.8 X 10(6)/mm2, while in the grafts from the treated group it was 0.960 X 10(6)/mm2. The decreased platelet deposition was significant in all graft segments (P less than 0.01). Fibrin deposition was reduced from 3.38 micrograms/mm2 to 0.25 micrograms/mm2 (P less than 0.01) by ibuprofen. Although fibrin and red blood cells are the major constituents of venous thrombi, platelet aggregation appears to play an important role if prosthetic material is implanted into the venous system. Ibuprofen not only reduced platelet deposition by 13.5-fold, but also reduced fibrin deposition by 13.5-fold. The ratio of platelets to fibrin in control and treated animals was similar (3.84 and 3.79, respectively). These data suggest that antiplatelet medication combined with heparin therapy might decrease early thrombus formation in venous prostheses.     

Effect of volume expanders on the lysability of ex vivo thrombi in the rabbit

The lysability of ex vivo thrombi before and after the infusion of dextran 70 (0.5 g/kg, 1.5 g/kg and 2 g/kg), dextran 40 (1.5 g/kg), albumin 5% (1.5 g/kg) and normal saline (0.3 g/kg) was studied in rabbits. All rabbits received 125I fibrinogen before the experiment. The thrombi were treated with plasmin or sodium chloride and the radioactivity released in the supernatant by the thrombus was determined. The thrombus weight was also recorded. A gradual increase in the lysability of thrombi after dextran 70 administration was observed and the maximum effect occurred 24 hours later. Increasing dose of dextran 70 did not potentiate the release of 125I fibrin degradation products in the supernatant, but did significantly decrease the thrombus weight during the first hours postinfusion, Dextran 40 was found to have a similar action but the effect was shorter and the lysability at 24 hours was similar to the preinfusion values. Albumin 5% and normal saline increase the radioactivity released from the thrombi to the supernatant but no change in the thrombus weight was observed. A similar result was obtained in the control group. The present investigation demonstrated that increasing doses of dextran 70 potentiate the effect on thrombolysis demonstrated by statistically significant decrease in the thrombus weight. Furthermore, albumin 5% and normal saline increase the release of 125I fibrin split products in the supernatant but did not have any effect on the thrombus weight and finally, the rabbit showed a marked spontaneous fibrinolysis probably related to the stress, anesthetic agent and surgical manipulation.     

Clinical implications of procoagulant and leukoattractant formation during intraoperative blood salvage

Experiments using 21 dogs and red cell salvage equipment (Haemonetics Cell Saver, Haemonetics Corp, Braintree, Mass) were employed to study the formation and potency of procoagulant and leukoattractant material during experimental autologous blood salvage. Washed red cell suspensions were found to include toxic degradation products that had been released from a deposit of platelets and white cells adherent to the centrifuge bowl wall. When reinfused, these toxic products resulted in a "salvaged blood syndrome" of intravascular clotting and pulmonary damage. The pulmonary arterioles showed leukocyte margination and tangled fibrin skeins with occlusive thrombi. Intra-alveolar and perivascular hemorrhages, along with extensive pulmonary edema, were also observed. The formation of procoagulant and leukoattractant material could be markedly decreased when the red cell salvage technique incorporated the following precautions: (1) minimal dilution with saline (normal plasma protein levels), (2) a low calcium level, and (3) minimal platelet activation (avoidance of the aspiration of clotted blood just before processing).     

The Vicious Cycle of Nonhealing Neointima in Fabric Vascular Prostheses

Abstract: Delayed neointimal healing of a fabric vascular prosthesis was investigated in an animal study focusing on the relationship between red thrombus, fibrinolysis, and endothelialization on the luminal surface. Fabric vascular prostheses were implanted into the descending aortas of 72 dogs. Fifty-nine grafts were explanted from 1 h to 1,705 days after implantation. One hour after implantation, the graft wall was red in color due to fresh thrombus; however, at 1 day the luminal surface became white. Red thrombus reappeared at 1 week and remained present in the long-term. Microscopically the initial red thrombus contained numerous erythrocytes. The white thrombus at 1 day was composed of a dense fibrin network without erythrocytes. At 2 days numerous lacunae appeared in the fibrin layer, and at 3–5 days cavernae and low density fibrin areas were present secondary to fibrinolysis. These areas allowed the blood components to infiltrate into the fibrin layer, and as a result red thrombus reformed within it. The thrombi on the luminal surface in the long-term was always red in color and composed of complicated, multiple stages of thrombus formation, i.e., fresh thrombus with erythrocytes, dense fibrin without erythrocytes, low fibrin density areas, lacunae and cavernae in the fibrin layer, and blood component infiltration into these spaces. Thrombus was always newly formed and present, and involuted in parallel due to fibrinolysis, suggesting that these phenomena perpetuated in a vicious cycle. However, at the anastomoses fibrinolysis was present, but blood component infiltration was prevented by the endothelial cell lining. These results suggest that endothelialization may arrest the vicious cycle of non-healing neointima in fabric vascular prostheses.     

Occlusive thrombosis with neovascularization of the internal carotid artery--two case report--

Two patients presented with sudden onset of occlusive thrombosis of the atherosclerotic carotid artery. The patients underwent carotid endarterectomy. Histological examination of the specimens clearly showed the presence of pre-existing atherosclerotic plaque with moderate stenosis and occlusive organized thrombus. Blood flow was maintained through a honeycomb pattern of multiple neovascularization within the organized thrombus. These cases suggest that both the degree of stenosis and the plaque characteristics should be considered when evaluating the risk of stroke in patients with carotid artery stenosis.     

An animal model for venous thrombosis and spontaneous pulmonary embolism

STUDY DESIGN:An animal model.OBJECTIVE:To test the natural sequence of venous thrombosis and pulmonary thromboembolism experimentally.SETTING:Veterans Administration Hospital, USA.METHOD:In dogs, a venous thrombosis was induced in a isolated segment of the internal jugular vein by a 5 min exposure to sodium morrhuate and then re-establishing venous patency. A tracer, (125)I human fibrinogen, was administered through another vein 1 h prior to the end of each experiment when a blood sample, the venous thrombus, and the lungs were removed. Thrombi were described by age, weight, histology, and fibrin uptake (thrombus to blood radioactivity ratio, g/g). Pulmonary emboli (PE) were identified by autoradiography of lung slices or by microscopic examination of lung sections.Results:Venous thrombosis developed in all experiments, duration 1-64, median 5 h (n=12). Histologically, younger thrombi were characterized by platelet aggregates surrounded by polymorphonuclear leukocytes (PMN), and uniform fibrin deposit; the older thrombi by platelet ghost cells, fewer PMN leukocytes, and broken fibrin strands and loops (n=6). Pulmonary thromboemboli were imaged as 'hot spots' in six of six experiments in which lung slices were autoradiographed and were identified microscopically in six of six experiments in which lung sections were taken. The number of PE diagnosed microscopically did not correlate with the age of the corresponding thrombus but was directly related to fibrin uptake (n=5, r=0.99, P<0.01).CONCLUSION:An animal model for venous thrombosis that generates pulmonary thromboembolism has been described.     

Intimal hyperplasia producing thrombus organization in an experimental venous thrombosis model

Purpose: A venous thrombosis animal model demonstrated similarities between intimal hyperplasia and thrombus organization. This has prompted the evaluation of a hypothesis that intimal hyperplasia may be the mechanism for thrombus organization in veins with normal pressure.Methods: Thrombi were produced in surgically exposed jugular veins of anesthetized, 18 to 20 kg pigs. Thrombosis was induced by a combination of devascularization, electric injury produced by a low amperage, direct current, and permanent partial ligation (50% diameter reduction). Vein segments were harvested at 0, 1, 2, 7, 14, and 60 days and histologically examined for fibrin, red blood cells, platelets, smooth muscle cells, endothelial cells, elastic fibers, and collagen deposits.Results: Forty vein segments in 20 pigs were evaluated. Luminal thrombi with thickened walls developed in all specimens. All luminal thrombi demonstrated partial spontaneous thrombolysis over the period of observation. Intimal thickening consisting primarily of smooth muscle cells by day 2 was apparent and progressed until about 2 weeks, when collagen deposits became prominent within the neointima. The neointima frequently comprised half the cross-sectional area of the veins. Endothelial cefls were present in the intima as single cells or as lining for clefts formed within the thickened intima.Conclusions: Smooth muscle cell proliferation with collagen deposition characteristic of intimal hyperplasia seemed to be the mechanism of thrombus organization in the experimental thrombosis model used in this study in which extensive stimulation was used to produce thrombosis. (J VASC SURG 1994;19:350-60.)     

Evaluation of the effect of pharmacologic agents on crush-avulsion arterial injuries: a scanning electron microscopy study.

This study was designed to investigate the short-term formation and composition of thrombus occurring at sites of arterial intimal injury in rabbits. Anti-coagulants, platelet anti-aggregation agents, and fibrinolytic agents were evaluated for their influence upon the developing thrombus, utilizing scanning electron microscopy to determine thrombus surface composition. These agents included: heparin, aspirin, dextran 40, streptokinase, and prostacyclin. The results are consistent with the known nature of each of these agents. When two agents were given simultaneously, each acting on different aspects of thrombogenesis (platelets vs. fibrin), the outcome appeared synergistic, with substantial reduction in thrombus accumulation; clear inhibition of both platelet aggregation and fibrin polymerization was noted. These findings support the clinical use of two agents used simultaneously, one inhibiting fibrin strand formation and the other inhibiting platelet adherence aggregation, for the prevention of micro-arterial thrombosis.     

Characterization of antithrombotic activity of lumbrokinase-immobilized polyurethane valves in the total artificial heart

Thirty ng/mm2 lumbrokinase, a potent fibrinolytic enzyme, was immobilized in a Korean type total artificial heart (KORTAH) valve by photoreaction; polyallylamine was used as a photoreactive linker. Lumbrokinase-immobilized polyurethane valves were then fitted to the total artificial hearts of 3 healthy 50 kg lambs. In the control lamb, the valves were untreated; in one other, only valves on the right were treated; and in the remaining animal, only those on the left. Implants were in place for up to 3 days, and cardiac output was 5 L/min. To facilitate thrombus formation, low doses of heparin were administered. In the control lamb, thrombi was observed only in the inlet parts of the valves. In the other 2 experiments, thrombi formed in untreated control valves but not in lumbrokinase treated valves. The grade of thrombus formation in untreated valves was 1.06+/-1.37 versus 0+/-0 in the treated part by one-sided Student's t-test (p < 0.1). After implantation, fibrinolytic activity was only observed in treated valves by fibrin plate methods. The proteolytic activity of the treated valves was 3 times higher than that of untreated valves using the azocasein method. These data show that lumbrokinase treated polyurethane valves lead to decreased thrombus formation in vivo and that their biocompatibility is therefore greater than that of untreated valves.     

Mural thrombus of the aorta

Twenty-six peripheral arterial emboli complicating 14 cases of mural thrombi of the aorta were diagnosed between January 1978 and December 1986. None of these patients had any cardiovascular history; their mean age was 49 years. Presenting signs were acute ischemia of the lower limbs in 12 cases and chronic ischemia in two. Arteriograms and CT scan were diagnostic. The mural thrombi were infrarenal in 13 cases and suprarenal in one. Treatment of the thrombus was surgical in all but one patient. In four cases, treatment of the underlying cause was simultaneous with embolectomy; in nine patients, treatment was secondary because further workup was needed. In one case, the patient died following embolectomy before definitive treatment could be undertaken. Results were considered good in 11 cases (unlimited walking distance, no recurrent emboli), and poor in three cases (two major amputations and one death). The incidence of mural thrombi is not known. In our experience, they accounted for 3.8% of nonaneurysmal aortoiliac lesions operated upon during a nine-year period and were responsible for 5% of peripheral arterial emboli. Mural thrombosis of the aorta constitutes a dangerous condition with a potentially lethal final outcome. Recurrent emboli are inevitable without surgical treatment of the source.     

Immunohistochemical evaluation of failed vessel anastomoses in clinical microsurgery.

Failed vessel anastomoses collected from 12 patients during elective free flap surgery, and from one patient after failed mid-hand replantation were subjected to immunohistochemical analysis. The anastomotic failure was due to an obvious thrombosis, poor flow, an excessively sharp pulse or some other reason causing a non-functioning anastomosis. A total of 17 samples were obtained, 13 of them arterial, three between the artery and vein graft, and one venous. The majority of samples were resected during primary surgery and four of them at reoperation. Variables of coagulation and fibrinolysis were analysed repeatedly during the operation in 7/13 patients. Total occlusion was seen in 6/17 samples and a non-occlusive thrombus in 4/17; two of these were due to suture error. Immunohistochemistry showed that, overall, the endothelial cells (PECAM-l, CD 31) were absent and that the staining pattern for platelets (CD 42b and CD 31) and fibrin (fibrin II, T2G1) correlated. In the absence of a thrombus, however, adherent platelets were positive only for CD 42b, not for PECAM-1. Vessel inflammation was a prominent feature at reoperations. Analysis of coagulation and fibrinolytic markers (thrombin-antithrombin III complex, prothrombin fragment 1 + 2 and D-dimer) confirmed the occurrence of thrombosis in three patients undergoing breast reconstruction with clinically obvious thrombosis during primary surgery or at reoperation. Moreover, the patients with active cancer (2/7) were clearly hypercoagulable compared with the other patients. In short, the primary anastomotic failure was associated with loss of endothelial cells, and with co-localised platelet recruitment and fibrin formation at these sites. At reoperation, inflammation was a prominent feature at the vessel site of thrombi.     

A rare case of 2 free thrombi in left atrium with mitral stenosis

A 64-year-old female was admitted with general fatigue and orthopnea. Preopertive echocardiography showed a free ball thrombus in the left atrium, mitral stenosis and severe tricuspid regurgitation. To avoid a herniation of thrombus to the mitral orifice, an emergency operation was performed. Two free and small mural thrombi were found in the left atrium. Thrombectomy, mitral valve replacement and tricuspid annuloplasty were performed successfully. Postoperative course was uneventful, and she was discharged in good condition on the 21st postoperative day.