Parameters of Haemostasis during Acute Venous Thrombosis

Congenital Thrombophilia in Patients With Superior Mesenteric Venous Thrombosis or Portal Vein Thrombosis

We explored the relationship between abdominal vein thromboses, including portal vein thrombosis (PVT) and superior mesenteric vein thrombosis (SMVT), and thrombophilia. The frequency of thrombophilia, such as antithrombin (AT), protein C (PC), or protein S (PS) gene mutations, was examined in 21 patients with PVT, 6 patients with SMVT, and 6 patients with both PVT and SMVT. Low levels of AT, PC, or PS were frequently detected in patients with PVT or mesenteric vein thrombosis, and 4 mutations in the PS gene, 3 mutations in the PC gene, and 2 mutations in AT the gene were detected. Protein S Tokushima was detected in 3 of 4 patients with a PS gene mutation and was associated with 2 other PS gene mutations. The onset of PVT or SMVT was almost idiopathic in patients with congenital thrombophilia. Both PVT and SMVT were frequently caused by an AT, a PC, or a PS mutation, and the onset of these thromboses due to thrombophilia was frequently idiopathic.

Mesenteric and portal vein thrombosis: treated with early initiation of anticoagulation

OBJECTIVE

Superior mesenteric vein thrombosis (SMVT) is generally difficult to diagnose and can be fatal. Mesenteric and portal vein thrombosis is rare and can be presented as more serious conditions than that of SMVT. We report patients with combined SMVT and portal vein thrombosis (PVT) who were treated successfully with early initiation of anticoagulation.

METHODS

The medical records of six patients (five male, one female) who presented with combined SMVT and PVT in our institute between January 1994 and September 2003 were reviewed retrospectively. All of the patients were treated with early initiation of anticoagulation using unfractionated heparin or low molecular weight heparin.

RESULTS

The mean hospital stay was 31 days and the mean follow-up period was 32 months. Three patients had an antithrombin III deficiency. The most common symptom was diffuse abdominal pain and signs included abdominal distension and tenderness. During the follow-up period, there were two patients who developed stricture of the small bowel necessitating resection and anastomosis of the small bowel. There was no case of peritonitis due to bowel necrosis or mortality.

CONCLUSION

The early initiation of anticoagulation in patients of SMVT combined with PVT could minimise the serious complication such as peritonitis due to bowel necrosis required immediate exploratory laparotomy.

Normal Functional Protein S Activity Does Not Exclude Protein S Deficiency

Protein S (PS) deficiency appears to increase the risk of venous thrombosis. PS deficiency is classified into three phenotypes using antigenic levels and functional activity. By definition, all three phenotypes of PS deficiency should result in low activated protein C cofactor activity. We compared the results of functional PS activity testing to free antigenic PS testing in order to determine if a normal functional PS activity assay result could eliminate the need for free antigenic PS testing. The sensitivity of the functional assay is 45.5% (95% confidence interval, CI, 36-55%), specificity 95.3% (95% CI 93-97%), negative predictive value 88.6% (95% CI 86-91%) with a positive predictive value of 68.5% (95% CI 57-79%). In conclusion, a normal functional PS activity result does not exclude free antigenic PS deficiency. Functional PS activity testing should not be used as a screening test to eliminate free antigenic PS testing for the laboratory diagnosis of PS deficiency.

Antithrombin deficiency: issues in laboratory diagnosis

OBJECTIVE

To review the current understanding of the pathophysiology of antithrombin deficiency and its role in congenital thrombophilia. Recommendations for diagnostic testing of antithrombin function and concentration, derived from the medical literature and consensus opinions of recognized experts in the field, are included. These recommendations specify whom, how, and when to test.

DATA SOURCES

Review of the published medical literature.

DATA EXTRACTION AND SYNTHESIS

A summary of the medical literature and proposed testing recommendations were prepared and presented at the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia. After discussion at the conference, consensus recommendations presented in this article were accepted after a two-thirds majority vote by the participants.

CONCLUSIONS

Antithrombin deficiency is an infrequent genetic abnormality that may be a significant contributing cause of thrombophilia. Antithrombin deficiency also may be observed in conjunction with other genetic or acquired risk factors. Assay of antithrombin plasma levels is appropriate in the laboratory evaluation of individuals with thrombophilia, preferably using a functional, amidolytic antithrombin assay. The diagnosis of antithrombin deficiency should be established only after other acquired causes of antithrombin deficiency, such as liver disease, consumptive coagulopathy, or heparin therapy, are excluded. A low antithrombin level should be confirmed with a subsequent assay on a fresh specimen, and family studies may be helpful to establish the diagnosis. Antigenic antithrombin assays may be of benefit in subclassification of the type of antithrombin deficiency and to confirm the decreased antithrombin level in patients with type I deficiency.

Decrease in sensitivity of D-dimer for acute venous thromboembolism after starting anticoagulant therapy

D-dimer testing is useful for the exclusion of acute venous thromboembolism (VTE). Anticoagulant therapy is expected to reduce D-dimer levels in patients with thrombosis and, consequently, it may not be safe to use D-dimer levels to exclude VTE after anticoagulant therapy has been started. The objectives of this study were to estimate the decrease in D-dimer levels after 24 h of heparin therapy and, applying this estimate to the results of a recent study, to calculate the expected reduction in sensitivity. Using pre-defined criteria, we first performed a literature review to determine whether, and by how much, D-dimer levels decrease within 24 h of starting heparin therapy in patients with acute VTE. Using D-dimer levels that were measured in a prospective study of patients with confirmed deep vein thrombosis and/or pulmonary embolism as baselines, we then determined the change in sensitivity (and specificity) that would result from the fall in D-dimer levels that the literature review suggested would have occurred after 24 h of heparin therapy. On the basis of the literature review, we calculated that mean D-dimer levels decrease by 25%, 24 h after starting heparin therapy in patients with acute VTE. This 25% decrease in D-dimer levels resulted in a decrease in sensitivity from 95.6% (95% confidence interval, 90.0-98.6) to 89.4% (95% confidence interval, 83.7-95.1). There is a decrease in D-dimer levels in patients with acute VTE 24 h after starting heparin therapy that is expected to result in a clinically important drop in sensitivity.

Natural anticoagulants (antithrombin III, protein C, and protein S) in patients with mild to moderate ischemic stroke

BACKGROUND AND PURPOSE

The role of the natural anticoagulants, antithrombin III (AT III), protein C (PC), and protein S (PS), in patients with mild to moderate ischemic stroke remains uncertain. We aimed to find out whether their levels in peripheral blood correlated with the severity of neurological deficit or can predict clinical outcome and recurrence.

METHODS

We studied AT III, PC, and free PS levels in 55 consecutive patients likely to survive the study period on admission, 1 week, 1 month and 3 months after a first-ever ischemic stroke. Sex- and age-matched controls were studied once. All patients underwent a full neurological examination and blood sampling at each study time point; comprehensive stroke risk factors were recorded, and the etiology of the ischemic stroke was determined. All patients were contacted 3 years later for possible recurrent ischemic events.

RESULTS

AT III level was found to be significantly lower at all time points after stroke; PC level was significantly increased on admission and normal at subsequent measurements, and PS level was normal on admission but significantly decreased later. The levels of the natural anticoagulants did not correlate with the etiology of stroke, any stroke risk factor, or neurological scores, except that the AT III level on admission showed significant correlation with stroke severity and disability at 3 months. Natural anticoagulant levels did not predict recurrence of ischemic stroke.

CONCLUSIONS

The measurements of the level of AT III, PC, or PS did not deliver useful information for management of patients with mild or moderate ischemic stroke, expect that AT III level on admission might predict outcome.

Occlusive vascular diseases in oral contraceptive users. Epidemiology, pathology and mechanisms

Despite being an unprecedented departure from normal physiology, the combined oral contraceptive is not only highly effective, but it also has a remarkably good safety record. Concerns over safety persist, though, particularly with regard to venous thromboembolism (VTE), stroke and myocardial infarction (MI). Epidemiological studies consistently show an increase in risk of VTE, but the results are more contentious with regard to arterial diseases. Despite 40 years of research, the mechanisms behind these adverse effects are not understood. In this review, we integrate information from published studies of the epidemiology and pathology of the occlusive vascular diseases and their risk factors to identify likely explanations for pathogenesis in oral contraceptive users. Oral contraceptives induce both prothrombotic and fibrinolytic changes in haemostatic factors and an imbalance in haemostasis is likely to be important in oral contraceptive-induced VTE. The complexity of the changes involved and the difficulty of ascribing clinical significance has meant that uncertainty persists. A seriously under-researched area concerns vascular changes in oral contraceptive users. Histologically, endothelial and intimal proliferation have been identified in women exposed to high plasma estrogen concentrations and these lesions are associated with thrombotic occlusion. Other structural changes may result in increased vascular permeability, loss of vascular tone and venous stasis. With regard to arterial disease risk, epidemiological information relating to dose effects and joint effects with other risk factors, and studies of pathology and changes in risk factors, suggests that oral contraceptive use per se does not cause arterial disease. It can, nevertheless, synergise very powerfully with subclinical endothelial damage to promote arterial occlusion. Accordingly, the prothrombotic effects of the oral contraceptive estrogen intervene in a cycle of endothelial damage and repair which would otherwise remain clinically silent or would ultimately progress - in, for example, the presence of cigarette smoking or hypertension - to atherosclerosis. Future work in this area should focus on modification of the effects of established risk factors by oral contraceptive use rather than modification of the supposed risk of oral contraceptive use by established risk factors. Attempts to understand vascular occlusion in oral contraceptive users in terms of the general features of VTE or with reference to atherosclerosis may be limiting, and future work needs to acknowledge that such occlusions may have unique features. Unequivocal identification of the mechanisms involved would contribute considerably to the alleviation of fears over vascular disease and to the development of even safer formulations.

Selective thrombolysis in acute deep vein thrombosis: evaluation of adjuvant therapy in vivo

PURPOSE

To evaluate in a porcine model of acute deep vein thrombosis (DVT) the efficacy of dalteparin and antithrombin with respect to heparin for local adjuvant therapy during selective thrombolysis, and the utility of nitroglycerin and iloprost as heparin supplements.

METHODS

DVT was induced in both hind limbs using a previously described technique (n = 20). Thirty minutes later, the animal was heparinized (2500 IU IV), and bilateral sequestrated thrombolysis was performed using 8 mg alteplase: both external iliac veins were endoluminally occluded with Swan-Ganz catheters, and a multi-sideport infusion wire coaxially introduced through each catheter and advanced into the ipsilateral popliteal vein. In the control limbs, tissue plasminogen activator (tPA) 8 mg was injected as 0.8-ml boluses at 3-min intervals for 2 hr as a 0. 25-mg/ml solution containing heparin 50 IU/ml (n = 20). On the contralateral side, heparin was substituted with either dalteparin 50 IU/ml (n = 5) or antithrombin 12.5 IU/ml (n = 5), or supplemented with either nitroglycerin 0.075 mg/ml (n = 5) or iloprost (150 ng/ml) (n = 5). Blood samples were taken at predetermined intervals to measure the activated partial thromboplastin time (aPTT), prothrombin time (PT), and fibrinogen concentration. At autopsy, the thrombus mass in the iliofemoral veins was measured, and the extent of residual thrombosis in the venous tributaries graded at four sites.

RESULTS

Bilateral thrombolysis was successfully completed in all animals. The median thrombus mass in the iliofemoral veins after thrombolysis was 0.48 g (range 0.06-1.58 g), 0.95 g (0.59-1.29 g), 0. 74 g (0.52-0.96 g), and 0.29 g (0.0-0.77 g) for dalteparin, antithrombin, iloprost, and nitroglycerin respectively, as compared with 0.53 g (0.18-0.88 g) (p = 0.69), 0.97 g (0.46-1.15 g) (p = 0. 69), 0.53 g (0.48-1.10 g) (p = 0.69), and 0.18 g (0.13-1.04 g) (p = 0.5) for the respective controls. Likewise, the severity of residual thrombosis in the venous tributaries was not affected by the constituents of adjuvant therapy. Nitroglycerin induced a small drop in blood pressure, which was transient. The temporal change in aPTT was similar in all four groups. Invariably PT progressively shortened during thrombolysis (p = 0.0001); this effect was somewhat blunted with antithrombin. Fibrinogen levels demonstrated a time-dependent increase (p = 0.004) that was not influenced by the adjuvant therapy used.

CONCLUSIONS

Dalteparin or antithrombin demonstrated no appreciable advantage over heparin as local adjuvant therapy for selective venous thrombolysis. Supplementation of heparin with iloprost or nitroglycerin also had virtually no effect on thrombolytic efficacy.

Mesenteric and portal vein thrombosis in a young patient with protein S deficiency treated with urokinase via the superior mesenteric artery

A 32-year-old man, who was previously healthy, had acute abdominal pain without peritonitis. Diffuse mesenteric and portal vein thrombosis were shown by means of a computed tomography scan. A protein s deficiency was found by means of an extensive workup for hypercoagulable state. Successful treatment was achieved with urokinase infusion via the superior mesenteric artery without an operation. This represents an attractive alternative approach to treating patients with this disease. The previous standard of operative intervention(1) can now be reserved for complications, such as bowel infarction with peritonitis, or for those patients with absolute contraindications to thrombolytic therapy.

Antiphospholipid antibodies and coagulation regulatory protein abnormalities in children with pulmonary emboli

PURPOSE

To evaluate the demographics, presentation, family history, and laboratory findings in children with clinically recognized pulmonary emboli.

METHODS

Data were collected about children with clinically recognized pulmonary emboli from 1987 to 1994 at two pediatric hematology referral centers.

RESULTS

Sixteen children, mean age 11.8 years (standard deviation 4.69 years) including 11 boys were affected. Lower extremity thromboses were present in 7/14 children evaluated. Eight of the 16 children were apparently well before development of pulmonary emboli; seven were found to have antiphospholipid antibodies. None of the 15 children tested were antithrombin III deficient. One of 14 children tested was protein C deficient. Three of 13 children tested were protein S deficient or had a free protein S antigen at the fifth percentile. One of 10 children tested had an acquired dysfibrinogenemia. Two of nine children tested had the Factor V Leiden mutation.

CONCLUSIONS

Our limited data suggest at least 70% of children with pulmonary emboli referred for hematology evaluation have antiphospholipid antibodies and coagulation regulatory protein abnormalities.

Activation of the coagulation cascade in untreated primary open-angle glaucoma

PURPOSE

The authors studied the coagulation cascade and fibrinolysis pathway in patients with untreated glaucoma (P = 0.00001 and P = 0.0003, respectively) and patients with normal pressure glaucoma ([NPG] P = 0.00001 and P = 0.03, respectively).

METHODS

Forty-two untreated patients with NPG, 25 untreated patients with primary open-angle glaucoma (POAG), and 32 age-matched normal controls were recruited. Patients taking anticoagulant therapy beta blockers or calcium channel blockers were excluded. Venous blood was assessed for markers of the coagulation and fibrinolysis pathways using enzyme-linked immunosorbent assay techniques.

RESULTS

Patients with POAG had elevated levels of prothrombin fragments 1 + 2 and D-dimer compared with both the NPG and controls (P = 0.00001 and P = 0.0003, respectively). Both glaucoma groups had more (P < 0.05) systemic vascular disease than the control group. The patients with POAG had higher (P < 0.05) systemic blood pressure (systolic and pulse pressure) than the control and NPG groups. Both glaucoma groups had greater levels of fibrinogen (which was of borderline statistical significance) than the control group.

CONCLUSION

Elevated levels of prothrombin fragments 1 + 2 and D-dimer indicate activation of the coagulation cascade and fibrinolysis pathway, respectively, leading to a hypercoagulable state in untreated POAG. These findings may contribute to the reported increased prevalence of retinal venous thrombosis in glaucoma and also to the pathogenesis of optic nerve damage in glaucoma.