E.A.R. Knot

A shift in balance between profibrinolytic and antifibrinolytic factors causes enhanced fibrinolysis in cirrhosis

The aim of this study was to assess the cause of enhanced fibrinolysis in cirrhosis by studying the balance between profibrinolytic and antifibrinolytic proteins in 24 patients with mild or severe cirrhosis. Antigen levels of both tissue-type plasminogen activator and plasminogen-activator inhibitor 1 were increased in mild and severe cirrhosis. Activity levels showed a very wide variability, but median activity levels of both proteins were normal. In most patients, the increase in tissue-type plasminogen activator was counterbalanced by the increased levels of plasminogen-activator inhibitor 1, but in a subgroup of patients the change in balance resulted in extremely high tissue-type plasminogen-activator levels. The specific activity of both proteins (activity/antigen quotient) was reduced in either mild or severe cirrhosis. This finding indicates either that more enzyme-inhibitor complexes circulate in the blood of patients with cirrhosis than in normal individuals or that dysfunctional molecules circulate. Plasminogen and alpha 2-antiplasmin antigen and activity levels were decreased in both mild and severe cirrhosis. The binding of alpha 2-antiplasmin to fibrin was decreased in severe cirrhosis, making fibrin clots more susceptible to lysis. Clot lysis experiments were performed to see if equal decreases in plasminogen and alpha 2-antiplasmin levels, as found in cirrhosis, result in a change in the rate of fibrinolysis. It was found that the proportionate decreases led to enhancement of fibrinolysis, indicating that the inhibitor depletion is more important than the proenzyme depletion. The authors conclude that enhanced fibrinolysis frequently found in cirrhosis may be attributed to an increased tissue-type plasminogen-activator activity relative to plasminogen-activator-inhibitor activity and decreased levels of alpha 2-antiplasmin, resulting in a reduced binding of alpha 2-antiplasmin to fibrin.

Role of the donor liver in the origin of platelet disorders and hyperfibrinolysis in liver transplantation

We investigated the role of the donor liver in the origin of platelet disorders and hemostatic defects in liver transplantation. Eighteen pigs received an orthotopic or a heterotopic, auxiliary liver graft. Liver biopsies were taken for electron microscopic studies 5-10 min after reperfusion in nine animals. Blood samples were taken from the first hepatic outflow and from the systemic circulation before and 5 min after graft recirculation. Electron microscopy did not show any evidence of microthrombi or platelet aggregation in the graft, either after orthotopic liver transplantation or after heterotopic liver transplantation. Most blood platelets, which were lying free in the sinusoids, showed cell processes and many seemed to have lost their granulae, suggesting a degree of platelet activation. There were also signs of phagocytosis of platelets by the Kupffer cells. In the hepatic outflow, platelet count was significantly lower (p < 0.05) and fibrinolytic activity significantly higher (p < 0.01), than systemic post-reperfusion values. There were no important changes in the coagulation parameters. No significant changes were found between the effects on hemostasis of orthotopic and auxiliary graft reperfusion. In the second part of the study evidence for platelet activation was found after graft reperfusion in human liver transplantation. Plasma levels of platelet factor-4 and beta-thromboglobulin increased significantly after graft reperfusion. These studies suggest that platelet disorders and increased fibrinolytic activity are the major components of the hemostatic defect after graft recirculation in liver transplantation. Sequestration of platelets in the graft is probably due to the accumulation of (activated and degranulated) platelets in the sinusoids and phagocytosis by Kupffer cells.

Disseminated intravascular coagulation in liver cirrhosis

UNLABELLED We measured thrombin-antithrombin III complex (TAT), soluble fibrin (SF) and D-dimer levels in 51 patients with liver cirrhosis to determine whether these tests provide new evidence for the presence of disseminated intravascular coagulation (DIC) in liver cirrhosis. TAT levels (median, range) were increased in the patient group (4.2 micrograms/l, 1.8-60.0) compared to the reference group (2.0 micrograms/l, range 1.5-7.6 micrograms/l). SF levels (0 nmol/l, range 0-80 nmol/l) were also increased in the patients as compared to the controls (0 nmol/l, 0), but there was no correlation between TAT and SF levels (r = 0.23, p less than 0.98). TAT levels did not correlate with AT-III levels (r = -0.36, p less than 0.49), but there was an inverse correlation between SF and AT-III (r = 0.60, p less than 0.001). If AT-III levels were above 0.30 U/ml, SF levels remained low, whereas SF levels were increased in patients with AT-III levels below 0.30 U/ml. These findings suggest that if sufficient AT-III is present, thrombin formation is adequately controlled, whereas at low levels of AT-III, thrombin escapes inactivation by AT-III and may act upon fibrinogen, leading to the formation of SF and a low-grade DIC. SF levels correlated well with D-dimer levels (r = 0.55, p less than 0.001), which is consistent with DIC and secondary fibrinolysis. IN CONCLUSION (1) thrombin formation is increased in liver cirrhosis, as indicated by increased TAT levels in 21 of 51 patients; (2) the plasma concentration of AT-III appears to be of major importance for the development of DIC. The present study provides evidence for DIC in severe liver cirrhosis when AT-III levels are less than 0.30 U/ml.

Acid treatment of plasma for the inactivation of plasminogen activator inhibitor-1 (PAI-1)

The present study was initiated to assess the effectiveness of various acid treatments of blood or plasma in the inactivation of PAI-1. It was shown that a frequently used treatment of blood or plasma with 1 M acetate buffer, pH 3.9, only partially inactivated PAI-1. The inactivation of PAI-1 in plasma was found to depend upon pH and temperature, showing an optimal inactivation at a pH less than or equal to 3, at 37 degrees C.

Monitoring heparin and haemostasis during reconstruction of the abdominal aorta

In spite of its unpredictable kinetics, heparin is still not generally monitored during peripheral vascular surgery. To evaluate heparin levels and neutralisation, plasma heparin concentrations were measured using a chromogenic substate method during 20 consecutive operations on the Abdominal Aorta. This was combined with measuring activated partial thromboplastin time (APTT), thrombin time (ThT), prothrombin time (PT), antithrombin-III (AT-III) and fibrinogen concentration. Heparin concentration 5 min after administration and the elimination rate showed a wide variation. Using a standard dosage for all patients resulted in plasma heparin levels that are potentially too low in some patients. The APTT and ThT were found to be unsuitable for an exact calculation of heparin levels. Protamine administration based on the surgeons judgement of haemostasis was inadequate. Furthermore an intraoperative decrease of AT-III and fibrinogen was seen in eight patients. It is advisable and possible to have direct monitoring of heparin concentration during peripheral vascular surgery.

Coagulation and fibrinolysis in the first human auxiliary partial liver transplantation in rotterdam

Abstract Coagulation and fibrinolysis parameters were extensively monitored during and after a case of auxiliary partial liver transplantation (APLT). Preoperative coagulation tests demonstrated a severe liver dysfunction. Routine coagulation tests were prolonged and low levels of fibrinogen, antithrombin III (AT-III), and ( α 2 -antiplasmin ( α 2 -AP) were measured. Pro-urokinase (pro-UK), total Uk-antigen and plasminogen activator inhibitor (PAI) activity were increased (6.2; 5.4 ng/ml and 12.5 IU/ml, respectively). During transplantation no major changes in haemostasis were detected by either standard coagulation tests or thrombelastography and only a minimal increase of fibrinogen degradation products (0.6–1.0 μg/ml) was seen just before graft recirculation up till the end of the operation. PAI levels remained high during the operation and neither tissue-type plasminogen activator (t-PA) nor active urokinase (u-PA) were detectable. After APLT, graft function was reflected by normalisation of coagulation parameters and increase of AT-III and α 2 -AP to normal levels. Pro-Uk and PAI activity levels decreased after transplantation to normal values; a transient increase of t-PA activity (max. 1360 mIU/ml) was seen from the tenth to nineteenth day. It was demonstrated that a heterotopically placed partial liver allograft can provide synthesis of haemostasis factors and inhibitors and restore clearance which is adequate to reverse coagulopathy.

Diagnostic Value of D-Dimer for Deep Venous Thrombosis in Outpatients

We have studied the diagnostic value for deep venous thrombosis (DVT) of an enzyme immunoassay (EIA) for the detection of D-dimer in plasma of 239 consecutive outpatients suspected of having DVT by their general practitioner. DVT was confirmed by impedance plethysmography in 60 patients. Using the 95th percentile range of 42 healthy volunteers, the sensitivity for the detection of DVT was 92%, with a specificity of 21%. In our population with a prevalence of 25%, the D-dimer EIA showed a negative predictive value of 88% and a positive predictive value of 28%. We conclude that this D-dimer ELISA has limited value, either to confirm or to exclude DVT in outpatients.

Correlations between plasma levels of fibrin(ogen) derivatives as quantified by different assays based on monoclonal antibodies

New plasma assays for fibrin(ogen) degradation products have become available which are based upon monoclonal antibodies and can be performed in plasma. In this study we have evaluated four of such specific enzyme immuno assays i.e.: for the total of degradation products of fibrin and of fibrinogen (TDP), fibrin degradation products (D-dimer and FbDP) and fibrinogen degradation products (FgDP) in patients suspected of having deep venous thrombosis of the leg (DVT) and patients with cirrhosis of the liver. DVT was assessed by impedance plethysmography (IPG). In each of the (sub) groups of patients, a very good correlation (0.90 less than r less than 0.98) was observed between the actually measured TDP values and the calculated sum of the separately measured FbDP and FgDP levels. Only 2% (5 patients) of the cases showed a discrepancy of more than a factor two between the found TDP values and the calculated sum of the measured FbDP and FgDP levels. About 90% of the fibrin degradation products were crosslinked. FbDP levels correlated well with the FgDP levels (0.72 less than r less than 0.94) and D-dimer levels (0.82 less than r less than 0.91) in both patients with DVT and cirrhotics. In those patients also a good correlation (0.67 less than r less than 0.83) was observed between FgDP and D-dimer levels, but not in patients suspected of having DVT but with a normal IPG test result. Secondary fibrinolysis appeared to be accompanied by fibrinogenolysis.