Impaired fibrinolysis and postoperative thromboembolism in orthopedic patients.

The incidence of deep vein thrombosis (DVT) and pulmonary embolism was studied prospectively in patients undergoing elective total hip replacement. 96 patients were randomly allocated to receive either low molecular weight heparin (LMWH) or unfractionated heparin (UFH). All patients had bilateral phlebography and pulmonary perfusion/ventilation scintigraphy 10-12 days after surgery. The following fibrinolytic variables were analysed in plasma and related to thromboembolism: tissue plasminogen activator (t-PA) activity, t-PA antigen (t-PA Ag), plasminogen activator inhibitor (PAI-1) activity and PAI-1 antigen (PAI-1 Ag). No significant difference was found, regarding the fibrinolytic response to surgery, between patients treated with LMWH and UFH. The level of PAI-1 activity was significantly increased before operation in patients developing DVT as compared to non-DVT patients (p less than 0.03). Immediately after surgery and in the morning the first postoperative day the levels of PAI-1 activity, PAI-1 Ag and t-PA Ag were positively correlated to thromboembolism. PAI-1 activity was the only preoperative fibrinolytic variable correlated to thromboembolism.     

Preoperative identification of patients at high risk of deep venous thrombosis despite prophylaxis in total hip replacement

Clinical and laboratory variables were measured on the day before operation in 111 patients who underwent total hip replacement prophylactically treated with acetylsalicylic acid or heparin-dihydroergotamine. Postoperative deep vein thrombosis (DVT) was detected in 16 patients by ascending venography. Stepwise logistic discriminant analysis was used to identify DVT predicting factors. Three such factors, fibrinogen degradation products (FDP), plasminogen activator inhibitor (PA-inhibitor) and tissue type plasminogen activator (t-PA), were found to be significantly associated with DVT and were used to construct a predictive index. The predictive index, I = -2.09 + 0.46 (FDP) + 1.39 (PA-inhibitor) -0.24 (t-PA), was 100% sensitive and 95% specific in the prediction of DVT. This index would allow for identification of those patients in whom routine prophylaxis would be sufficient and for selecting those in whom more effective prophylactic regimens would be necessary.     

Tissue-type plasminogen activator, type 1 plasminogen activator inhibitor and their complex in plasma with disseminated intravascular coagulation.

The levels of tissue-type plasminogen activator (t-PA), type 1 plasminogen activator inhibitor (PAI-1), and t-PA/PAI-1 complex antigens were analyzed in the plasma of disseminated intravascular coagulation (DIC) patients and healthy controls. Other fibrinolytic parameters such as the levels of plasminogen, alpha 2-antiplasmin (alpha 2-AP), plasmin/alpha 2-AP (PAP), and D-dimer were also estimated to clarify the fibrinolytic states in these plasmas. The antigens of t-PA, PAI-1, and t-PA/PAI-1 complex were found to increase from 8.5 +/- 4.3, 54.4 +/- 21.2, and 8.6 +/- 3.5 ng/ml in normal plasma to 36.4 +/- 25.1, 106.8 +/- 54.7, and 46.6 +/- 34.5 ng/ml in DIC plasma, respectively. The molar ratio of total t-PA to total PAI-1 was 1:6 and 1:3 in normal plasma and DIC plasma, respectively, indicating an enhanced fibrinolytic state in the DIC plasma. The DIC plasma revealed a significant consumption of plasminogen (62.1 +/- 27.8%), and alpha 2-AP (63.7 +/- 25.3%) and an increase in PAP (2.6 +/- 2.7 micrograms/ml) and D-dimer (3.9 +/- 10.7 micrograms/ml). These results suggest that the production and secretion of t-PA and PAI-1 from endothelial cells were enhanced in DIC, resulting in an increased t-PA/PAI-1 complex with dominant fibrinolytic activity.     

Sequential intrapulmonary and systemic activation of coagulation and fibrinolysis during and after total hip replacement surgery

Hip joint replacement surgery, using acrylic cement for prosthesis fixation, is associated with intraoperative cardiorespiratory dysfunction, and a high frequency of postoperative proximal deep vein thrombosis (DVT). Levels of prothrombin fragments ₁₊₂ (F₁₊₂), tissue plasminogen activator antigen (t-PA), plasminogen activator inhibitor 1 activity (PAI-1), D-dimer and interleukin 6 (IL-6) were measured in arterial (AB) and mixed venous blood (MVB) in five patients during and after total hip replacement operation with acrylic cement prosthesis fixation. Sequential peaks of F₁₊₂, t-PA, PAI-1 and IL-6 appeared, starting with activation of coagulation during preparation of bone, closely followed by activation of fibrinolysis. Later, this was counteracted by an antifibrinolytic response and increase of IL-6. After a fibrinolytic shutdown on the third postoperative day as evidenced by a drop in t-PA and D-dimer concentrations, a second wave of coagulation was seen at the end of the first week. The present model, with frequent sampling of blood entering and leaving the lungs, confirms our earlier findings of the lung as a key organ in promoting coagulation following traumatic activation.     

Regional fibrinolysis following total hip replacement

The local effect of operative trauma on the fibrinolytic system was studied in ten patients undergoing total hip replacement. Catheters were inserted in the femoral veins on both sides and blood was sampled from these catheters perioperatively. The following fibrinolytic variables were analysed in plasma and related to the different steps of surgery: tissue plasminogen activator (t-PA) activity, t-PA antigen and plasminogen activator inhibitor (PAI-1) activity. During surgery PAI-1 activity and t-PA antigen in the operated limb were significantly increased compared with preoperative values. There was a significant difference in PAI-1 activity and t-PA antigen between the operated and the non-operated limbs during surgery and within one hour postoperatively. During fixation of the femoral implant there was a significant difference between the operated and the non-operated limbs in t-PA activity. Thus the regional fibrinolytic response to trauma was dissociated from the response in the non-operated limb. The clinical relevance of the observed alterations in regional fibrinolysis, as related to thrombogenic mechanisms after hip surgery, remains to be elucidated.     

Euglobulin clot lysis induced by tissue-type plasminogen activator is reduced in subjects with increased levels of lipoprotein (a).

Several reports have evaluated the in vitro effect of lipoprotein(a) [Lp(a)] levels on the fibrinolytic system, suggesting that high Lp(a) levels may inhibit fibrinolysis by competing for plasminogen binding in different systems. We have studied plasminogen activation induced by tissue-type plasminogen activator (t-PA), as well as other fibrinolytic parameters, in 25 subjects with Lp(a) levels greater than 30 mg/dl and the results were compared with those found in 23 subjects with Lp(a) less than 30 mg/dl. Both groups were similar in age, sex distribution, living habits and lipid pattern. Plasminogen activation, when measured by t-PA-induced euglobulin clot lysis, was significantly decreased in the group with elevated Lp(a) levels (lysis time, 16.7 +/- 3.3 min) compared with the group with low Lp(a) levels (11.8 +/- 2.0 min), although 8 of the 25 subjects with high Lp(a) levels showed plasminogen activation within the range of the control group. A positive significant correlation between Lp(a) levels and t-PA-induced euglobulin clot lysis time was found. No statistical differences were demonstrated between groups for the other fibrinolytic parameters studied. Addition of purified Lp(a) to the euglobulin fraction or to plasma resulted in a decrease in euglobulin clot lysis. The present study shows that t-PA induced plasminogen activation is decreased in individuals with high circulating levels of Lp(a) supporting the hypothesis that Lp(a) may interfere with the physiological functions of plasminogen.     

Tissue plasminogen activator concentrations in major abdominal surgery. Relationship to postoperative deep vein thrombosis

Tissue plasminogen activator (t-PA) antigen concentrations were studied in 47 patients subjected to major abdominal surgery. The 17 patients, which developed postoperative deep vein thrombosis (DVT), diagnosed with the 125I-fibrinogen uptake test, had higher levels preoperatively, and on the sixth postoperative day, when the thrombi had already formed. The reduced fibrinolytic activity in patients with a predisposition to postoperative deep vein thrombosis is thus not related to any t-PA deficiency. The postoperative fibrinolytic shutdown may however partly be due to a drop in t-PA antigen levels, at least in the patients, which developed DVT.     

Increased PA-inhibitor levels in the postoperative period--no cause-effect relation with increased cortisol

It has been reported that the level of PA-inhibitor increases in postoperative patients and on the other hand that glucocorticoids increase the PA-inhibitor level in cell culture. Because surgery is associated with increased plasma cortisol level, a relation between the postoperative increase in plasma cortisol and PA-inhibitor levels was looked for. Blood samples were collected from 8 patients undergoing extensive abdominal surgery, before operation and postoperatively at 2 hr, 4 hr, 24 hr and daily for 7 days. Plasma cortisol and PA-inhibitor were increased 2 hr after surgery, when there was a significant correlation (p less than 0.05). The maximum increase was at 24 hr and the values fell to normal on day 6. An increase in t-PA related antigen (t-PA R:Ag) and a decrease in euglobulin fibrinolytic activity (EFA) also occurred. In 7 controls 0.25 mg ACTH was given intravenously and blood was collected after 1/2, 1, 2, 4, 6 hr. Although the increase in plasma cortisol level following ACTH was comparable to that observed after surgery the increase was not associated with significant change in PA-inhibitor level, t-PA R:Ag or EFA. A cause-effect relationship between the increased plasma cortisol and PA-inhibitor level could not be shown. The mechanism of the postoperative increase in PA-inhibitor thus remains unknown.     

Heparin and fibrinolysis--comparison of subcutaneous administration of unfractionated and low molecular weight heparin

The effects on the fibrinolytic system after a single s.c. bolus injection (at 9 a.m.) of either 5000 IU conventional heparin or 5000 anti-Xa U of a fractionated low molecular weight heparin (Fragmin, KabiVitrum, Sweden) were investigated in 9 healthy volunteers. The effects were compared to those of an injection of normal saline in 6 volunteers. Samples for biochemical analyses were taken regularily during 6 hours after drug or placebo administration. In the coagulation system the following parameters were measured: Activated partial thromboplastin time (APTT), anti-Xa activity, thrombin time and fibrinogen. The fibrinolytic system was monitored by analysing: plasminogen, alpha 2-antiplasmin, fibrin(ogen) degradation products (FDP), euglobulin clot lysis time (ECLT), tissue plasminogen activator (t-PA) activity, t-PA antigen and plasminogen activator inhibitor (PAI) activity. Injection of the 2 drugs was followed by elevations in APTT and anti-Xa activity, and were more pronounced for Fragmin than heparin. The fibrinolytic system exhibited a diurnal variation with decreasing PAI activity and increasing t-PA activity during the day. Volunteers receiving normal saline (placebo) showed a similar pattern. The results were unrelated to heparin. It is concluded from this study that neither heparin nor Fragmin had any significant effect on the fibrinolytic parameters when measured after a single s.c. bolus injection since the observed variations were within the diurnal range.     

Association between plasma levels of tissue plasminogen activator and postoperative deep vein thrombosis--influence of prophylaxis with a low molecular weight heparin. The Venous Thrombosis Group

In a prospective, randomized controlled study, tissue plasminogen activator (t-PA) and tissue plasminogen activator antigen (t-PA:ag) were measured pre- and postoperatively in 40 consecutive patients undergoing total hip replacement. Patients received either a subcutaneous injection of low molecular weight heparin or placebo once daily. Deep vein thrombosis was diagnosed by bilateral phlebography. Patients who developed postoperative thromboembolic complications had significantly lower preoperative t-PA activity levels than patients who did not develop such complications. No difference was observed between the two groups with respect to t-PA:ag. Thromboprophylaxis with low molecular weight heparin did not cause any significant changes in t-PA activity and t-PA:ag. This study in high risk patients indicates that impaired fibrinolysis may be associated with development of thromboembolic complications after operation.     

The influence of coronary angiography and angioplasty on parameters of hemostasis and fibrinolysis

The influence of invasive investigations on parameters of hemostasis and fibrinolysis is generally unknown, although this has consequences for the design of prospective studies on the association between those parameters and regression or progression of atherosclerosis. We therefore determined hemostatic and fibrinolytic factors in 12 patients who were admitted to the hospital for coronary angiography (CAG; n = 5) or percutaneous transluminal coronary angioplasty (PTCA; n = 7). Blood samples were drawn under basal circumstances on the day before, the day of and the day after CAG or PTCA. Significant changes occur in the concentrations of platelets and white blood cells, hematocrit (Ht), von Willebrand factor antigen (vWF:ag), antithrombin III-activity (AT III-ag), antithrombin III-antigen (AT III-ant), fibrinogen, plasminogen, alpha2-antiplasmin (alpha2-AP), histidine-rich glycoprotein (HRG), and plasminogen activator inhibitor (PAI)-activity. Mean values of beta-thromboglobulin, platelet factor 4, factor VIII:C, tissue-type plasminogen activator activity (t-PA act) and euglobulin clot lysis time (ECLT) do not differ significantly. After correction for Ht, no significant differences exist between the day before and the day of the procedure; but on the day after CAG and PTCA significant differences occur in white blood cells, factor VIII:C, AT III-ag, alpha2-AP and PAI-act. It is concluded that principally blood samples for investigations on fibrinolysis may be taken on the day before or the day of CAG or PTCA without a loss of quality, if the values are corrected for Ht. Samples taken on the day after the procedure are not useful for such purposes.     

Diurnal variation of the fibrinolytic system

To elucidate which component(s) of the fibrinolytic system is (are) responsible for the diurnal variation of fibrinolytic activity we have studied several parameters of this system in 8 healthy male volunteers during a period of 24 h. Blood was collected at 8 a.m., 10 a.m., 12 a.m., 4 p.m., 8 p.m. and 8 a.m. next morning. The following tests were performed: euglobulin clot lysis time (ECLT), fibrinolytic activity of euglobulins on fibrin plates in the presence and absence of blocking antibodies to tissue-type plasminogen activator (t-PA) and/or urokinase (u-PA), overall plasminogen activator inhibitor (PAI) activity, antigen levels of t-PA, u-PA and PAI-1 and zymography of the euglobulin fraction after SDS-PAGE. From 8-10 a.m. to 4-8 p.m., total fibrinolytic activity increased by 113% (p less than 0.01) or 71% (p less than 0.01) when measured by ECLT or by fibrin plate assay, respectively. The immunoquenching experiments showed that this increase was entirely due to t-PA related activity whereas u-PA activity and t-PA/u-PA independent activity remained constant during the day. Average antigen levels of u-PA and t-PA in the afternoon were 6% and 25% lower than those measured in the morning. During this period, overall PAI activity and PAI-1 antigen decreased by 31% (p less than 0.01) and 52% (p less than 0.01) respectively. Electrophoretic-zymographic analysis of the euglobulins revealed that throughout the day the majority of t-PA was present in the form of the 110 kDa t-PA/PAI-1 complex. The intensity of this complex was lowest in the afternoon.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of oral stanozolol used in the prevention of postoperative deep vein thrombosis on fibrinolytic activity

Plasminogen, fibrinogen, antithrombin III, euglobulin lysis time, tissue plasminogen activator (t-PA) and fast-acting t-PA inhibitor were measured in 21 patients receiving either stanozolol (10 mg orally given for 14 days preoperatively) or subcutaneous heparin, during a continuing comparative trial in the prevention of postoperative deep vein thrombosis. Stanozolol treatment resulted in significant (p less than 0.01) increases between the 14th and 1st preoperative days in the plasma concentrations of plasminogen (3.4 to 4.9 Cu/ml) and antithrombin III (107% to 132%); t-PA levels did not increase significantly (6.0 to 16.0 mU/ml; p greater than 0.1). There were significant (p less than 0.02) falls in fast-acting t-PA inhibitor (132% to 75%) and fibrinogen (2.4 to 1.8 g/l). Surgery reversed the changes in fibrinolytic activity seen preoperatively in the stanozolol-treated patients, and similar changes were seen in the heparin-treated group. In this dosage, stanozolol does not appear to prevent the fibrinolytic shutdown which occurs after elective major surgery.     

The anatomical distribution of plasma fibrinolytic activity in man during cardiac catheterisation.

Regional circulating plasma levels of fibrinolytic activity were assessed in 15 patients undergoing cardiac catheterisation. The euglobulin clot lysis time (ECLT) was longer in the abdominal aorta (AA) than the inferior vena cava (IVC), (median difference -17.5 min, p = 0.008). This was associated with higher inhibition of plasminogen activator activity (PAI) in the AA than IVC, -1.75 IU/ml, p = 0.002. In the venous circulation the ECLT was higher in the peripheral venous sample than in the IVC, -25.5 min, p = 0.003, with higher PAI peripherally than in the IVC, -1.9 IU/ml, p = 0.001. There were no differences in ECLT, PAI, PAI-1:Ag or t-PA:Ag throughout the arterial circulation. These results demonstrate higher fibrinolytic activity with lower inhibitor activity in the venous compared to the arterial circulation. Within the venous circulation fibrinolytic activity is lower peripherally with increased inhibitor activity.     

Acute effects of retinoids on fibrinolysis before and after venous occlusion in healthy humans

The effects of acitretin and etretinate on the fibrinolytic system have been investigated in a double-blind, placebo-controlled cross-over study in twelve healthy volunteers. Euglobulin fibrinolytic activity, euglobulin clot lysis time, tissue-type plasminogen activator (t-PA) activity and antigen concentration in plasma were measured before and after 10 min of venous occlusion (VO), three hours after ingestion of the compounds. The plasminogen activator inhibitor (PAI) activity was also measured in each session before fibrinolysis stimulation. None of the parameters studied was significantly affected by the two retinoids in comparison with placebo. Our study demonstrates that a single oral dose of 100 mg of etretinate or acitretin, investigated 3 hours after drug administration does not significantly influence the fibrinolytic system in vivo in humans. This observation does not exclude an effect of retinoids after prolonged intake.     

Systematic elucidation of effects of tranexamic acid on fibrinolysis and bleeding during and after cardiopulmonary bypass surgery.

The aim of this study was to systematically elucidate the effects of tranexamic acid on fibrinolysis and bleeding during and after cardiopulmonary bypass (CPB) surgery. Twenty-two patients undergoing CPB surgery were randomized to receive 100 mg/kg tranexamic acid or an equal volume of saline after anesthesia induction and prior to skin incision. Plasma levels of tissue plasminogen activator (t-PA) antigen and activity, crosslinked fibrin degradation products (D-dimer), alpha2-antiplasmin-plasmin complex, and plasminogen activator inhibitor-1 (PAI-1) antigen were measured. Blood samples were obtained after induction of anesthesia, before, during, and after CPB, at the end of surgery, and the next morning after surgery. Intraoperative and postoperative blood loss during 24 h after surgery was recorded. Patients' demographics were similar between the two groups. No patients suffered from thrombotic complications after surgery. In the tranexamic acid group, fibrinolytic activity and secondary fibrinolysis as measured by t-PA activity and D-dimer were markedly suppressed during CPB surgery (P=.042 and P=.015, respectively). Decreased fibrinolytic activity and fibrinolysis were accompanied by reduction of perioperative bleeding in the tranexamic acid group. We could also find a good positive correlation between the peak levels of t-PA activity and D-dimer (r(2)=.4203, P=.0011). No differences in the t-PA antigen, PAI-1 antigen release, and plasmin inhibition by alpha2-antiplasmin were apparent between the two groups. In a randomized, prospective trial of patients undergoing CPB surgery, we demonstrated that the synthetic antifibrinolytic drug tranexamic acid effectively suppresses fibrinolysis by inhibiting t-PA and plasmin activity with clear reduction of perioperative blood loss. While tranexamic acid had no effects on the other important fibrinolytic inhibitors like PAI-1 and alpha2-antiplasmin.     

The diurnal increase in euglobulin fibrinolytic activity in women using oral contraceptives and in normal women, and the generation of intrinsic fibrinolytic activity

The diurnal fluctuations in plasma euglobulin fibrinolytic activity in women on oral contraceptives and in normal women showed similar patterns of increase. Following inactivation of inhibitors by flufenamate the individual increases and the evening levels did not differ. The diurnal increase was related to an increase in extrinsic (tissue-type) plasminogen activator (t-PA) activity, which contributes little to the total activity of the euglobulin fraction but induces an activation of the intrinsic system.     

Enhanced tissue factor pathway activity and fibrin turnover in the alveolar compartment of patients with interstitial lung disease

Bronchoalveolar lavage fluids (BALF) from patients with hypersensitivity pneumonitis (HP; n = 35), idiopathic pulmonary fibrosis (IPF, n = 41) and sarcoidosis (SARC, n = 48) were investigated for alterations in the alveolar hemostatic balance. Healthy individuals (n = 21) served as Controls. Procoagulant activity (PCA), tissue factor (TF) activity and F VII activity were assessed by means of specific recalcification assays. The overall fibrinolytic activity (FA) was measured using the (125)I-labeled fibrin plate assay. Fibrinopeptide A (FP-A), D-Dimer, plasminogen activators (PA) of the urokinase (u-PA) or tissue type (t-PA), PA-inhibitor I (PAI-1) and alpha2-antiplasmin (alpha2-AP) were determined by ELISA technique. As compared to Controls, all groups with interstitial lung disease (ILD) displayed an increase in BALF PCA by approximately one order of magnitude, and this was ascribed to enhanced TF activity by >98%. Accordingly, F VII-activity was increased in all ILD groups, and elevated FP-A levels were noted. There was no significant difference in procoagulant activities between the different ILD entities, but the increase in TF was significantly correlated with deterioration of lung compliance. Overall fibrinolytic activity did not significantly differ between ILD entities and Controls, although some reduction in IPF subjects was observed. Nevertheless, changes in the profile of the different pro- and antifibrinolytic compounds were noted. U-PA, but not t-PA levels were significantly reduced in all ILD groups. alpha2-AP was markedly elevated throughout, whereas PAI-1 levels were lowered. As a balance of     

Protraction of whole blood and plasma clot lysis in patients with high levels of an inhibitor of tissue-type plasminogen activator

The influence of the newly discovered, fast-acting inhibitor of tissue-type plasminogen activator (t-PA) on the lysis time of plasma clots was studied by visual observation of lysis of clotted citrated plasma after addition of purified t-PA. To a series of plasma samples with various concentrations of naturally occurring PA-inhibitor purified t-PA was added to a final concentration, which in pooled normal plasma is sufficient to induce clot lysis within a few hours. In those plasma samples with a high free inhibitor level, determined by measuring the recovery of the activity of added purified t-PA, clot lysis was retarded. Whole blood clots were made by clotting freshly collected non-anticoagulated blood with thrombin after admixture of a trace amount of radiolabeled fibrinogen and a fixed amount of t-PA. Lysis rate, read from the appearance of radioactivity in the serum after centrifugation, was significantly lower in clots obtained from subjects with a high free inhibitor level than in those with a low inhibitor level. It is concluded that the PA-inhibitor protracts clot lysis and may be relevant for physiological fibrinolysis.     

Absence of synergism between tissue-type plasminogen activator (t-PA), single-chain urokinase-type plasminogen activator (scu-PA) and urokinase on clot lysis in a plasma milieu in vitro

A potential synergic effect of tissue-type plasminogen activator (t-PA), single-chain urokinase-type plasminogen activator (scu-PA) or urokinase on clot lysis was investigated in a whole human plasma system in vitro. The system consisted of a human plasma clot labeled with 125I-fibrinogen, immersed in citrated whole human plasma, to which the thrombolytic agents were added. Clot lysis was quantitated by measurement of released 125I, and activation of the fibrinolytic system in the surrounding plasma by measurements of fibrinogen and alpha 2-antiplasmin. t-PA, scu-PA and urokinase induced a dose-dependent and time-dependent clot lysis; 50 percent lysis after 2 h was obtained with 5 nM t-PA, 20 nM scu-PA and 12 nM urokinase. At these concentrations no significant activation of the fibrinolytic system in the plasma was observed with t-PA and scu-PA, whereas urokinase caused significant alpha 2-antiplasmin consumption and concomitant fibrinogen degradation. The shape of the dose-response curves was different; t-PA and urokinase showed a log linear dose-response whereas that of scu-PA was sigmoidal. Combinations of t-PA and scu-PA, of t-PA and urokinase or of scu-PA and urokinase at thrombolytic doses of each showed no synergism for thrombolysis. Fifty percent clot lysis in 2 h was obtained at total concentrations of the combined agents of 5 to 15 nM with molar ratios ranging from 1:4 to 4:1.(ABSTRACT TRUNCATED AT 250 WORDS)