Hereditary Protein S Deficiency and Venous Thrombo-Embolism

Protein S, a vitamin K-dependent coagulation factor, is involved in the regulation of the anticoagulant activity of activated protein C.

Using an immunoradiometric assay for total protein S in plasma we identified 14 patients (7 male and 7 female) in three unrelated Dutch families as fulfilling the criteria for an isolated protein S deficiency. In 9 patients who were not receiving oral anticoagulant treatment the mean total protein S antigen concentration was 0.50 ± 0.08 U/ml (± S.D.) and the calculated free protein S concentration was 0.15 ± 0.01 U/ml (± S.D.). In the five patients who were on oral anticoagulant treatment the mean total protein S antigen was 0.23 ± 0.05 U/ml (± S.D.).

Seven of the 14 patients had a history of venous thromboembolism occurring at a mean age of 25 years and often without an apparent cause. Protein S deficiency is inherited as an autosomal dominant trait.

Homozygosity for a Novel Missense Mutation in the Prothrombin Gene Causing a Severe Bleeding Disorder

A patient with a severe bleeding tendency and hypoprothrombin-emia (Factor II activity 2%, Factor II antigen 5%) was screened for the presence of alterations in his prothrombin gene. Direct sequencing of PCR fragments derived from the coding and flanking regions of the prothrombin gene, revealed that the patient was homozygous for an A ⟶ G substitution in exon 3. This substitution predicts the replacement of Tyr 44 (TAC) by Cys (TGC) in the prothrombin molecule. Both parents were found to be heterozygous for the same mutation. Further family studies revealed complete cosegregation of the mutation with the prothrombin deficiency. Only the five homozygous brothers and sisters of the propositus were clinically affected (severe hemorrhages including epistaxis, soft tissue, muscle and joint bleedings in all, and severe hemorrhages in the two women). The bleeding tendency therefore seems to inherit as an autosomal recessive trait.

A comparative analysis of different automated von Willebrand factor glycoprotein Ib-binding activity assays in well typed von Willebrand disease patients

Essentials Von Willebrand ristocetin cofactor activity (VWF:RCo) is not a completely reliable assay. Three automated VWF activity assays were compared within a von Willebrand disease (VWD) cohort. Raw values for all three assays were virtually the same. An overall problem within type 2A/IIE VWD using VWF:GPIb-binding activity/VWF:Ag was observed.

SUMMARY

Background von Willebrand disease (VWD) is an inherited bleeding disorder caused by quantitative (type 1 and 3) or qualitative (type 2) von Willebrand factor (VWF) defect. VWD diagnosis and classification require numerous laboratory tests. VWF: glycoprotein Ib (GPIb)-binding activity assays are used to distinguish type 1 from type 2 VWD. Objectives Three different automated VWF:GPIb-binding activity assays were compared. Patients and methods BC-VWF:RCo (Siemens Healthcare Diagnostics), HemosIL® VWF:RCo (Instrumentation Laboratory) and INNOVANCE® VWF:Ac (Siemens Healthcare Diagnostics) were performed in a well typed VWD cohort (n = 142). Results Based on the three most used VWD parameters (FVIII:C, VWF:Ag and VWF:GPIb-binding activity) and using a cut-off of <0.70 for type 2 VWD revealed sensitivity and specificity of, respectively, 92% and 72.4% for VWF:RCo/VWF:Ag, 84% and 89.7% for VWF:GPIbR/VWF:Ag, and 92% and 85.1% for VWF:GPIbM/VWF:Ag, whereas a lowered cut-off of < 0.60 resulted in reduced sensitivity with increased specificity for all assays. Conclusion VWD classification based on FVIII:C, VWF:Ag and VWF:GPIb-binding activity revealed an overall problem with normal VWF:GPIb-binding activity/VWF:Ag within type 2, especially type 2A/IIE. Although all assays were practically identical, BC-VWF:RCo had higher %CV compared with both new assays but comparable lower limit of quantification (LLOQ) ~4 IU dL-1 . No clear improved distinction between type 1 and 2 VWD with new assays was seen.

BC-VWF

RCo and HemosIL® are ristocetin dependent, whereas INNOVANCE® does not rely upon ristocetin and is not influenced by VWF polymorphisms increasing VWF:GPIb-binding activity levels. INNOVANCE® seems to be the best choice as a first-line VWF:GPIb-binding activity assay, providing the best balance between sensitivity and specificity for type 2 VWD.

Duplex ultrasound, clinical score, thrombotic risk, and D-dimer testing for evidence based diagnosis and management of deep vein thrombosis and alternative diagnoses in the primary care setting and outpatient ward

Deep vein thrombosis (DVT) has an annual incidence of 0.2% in the urban population. First episodes of calf vein thrombosis (CVT) and proximal DVT are frequently elicited by risk factors, including varicose veins, cancer, pregnancy/postpartum, oral contraceptives below the age of 50 years, immobility or surgery. Leg pain and tenderness in the calf and popliteal fossa on physical examination may result from other conditions than DVT labeled as alternative diagnosis (AD) Congenital venous thrombophilia is present in every third first DVT, increased FVIII in every fourth first DVT, and FV Leiden/FII mutation in 40% of women on oral anticonceptive pill before reaching the menopause. Routine thrombophilia testing for FV Leiden/prothrombin mutation and FVIII as main risk factor for venous thrombosis is recommended. Primary superficial venous thrombosis (SVT) and DVT patients with a autosomal dominant family history of DVT are candidates for thrombophilia testing for congenital AT, PC and PS deficiency. The requirement for a safe diagnostic strategy of CVT and DVT should be based on an objective post-test incidence of venous thromboembolism (VTE) of less than 0.1% with a negative predictive value for exclusion of DVT of 99.9% during 3 months follow-up. Modification of the Wells score by elimination of the "minus 2 points" for AD is mandatory and will improve the diagnostic accuracy of CVT/DVT suspicion in the primary care setting and outpatient ward. The sequential use of complete DUS, ELISA D-dimer testing and modified clinical Wells' score assessment is safe and effective for the exclusion and diagnosis of CVT, DVT and AD. About 10% to 20% of patients with DVT develop overt post-thrombotic syndrome (PTS) at one year post-DVT, and both PTS and DVT recurrences further increase to about 30% during long-term follow-up. Objective risk stratification of PTS complications using DUS for recanalization and reflux and D-dimer testing will become an integral part in routine clinical practice to assess the optimal duration of wearing medical elastic stockings and anticoagulation for the prevention DVT recurrence as the best option to reduce the incidence and costs of suffering from irreversible PTS.

Application of PRV-1 mRNA expression level and JAK2V617F mutation for the differentiating between polycytemia vera and secondary erythrocytosis and assessment of treatment by interferon or hydroxyurea

Increased PRV-1 mRNA expression and the presence of Jak2(V617F) mutation in peripheral blood granulocytes are specific markers for chronic myeloproliferative disorders (MPD), which facilitate the differential diagnosis between polycythemia vera (PV) and secondary erythrocytosis (SE) and may be helpful for monitoring treatment efficacy in MPD patients. We evaluated the presence of the Jak2V617F mutation and increased PRV-1 mRNA expression along with previously established markers - erythropoietin (EPO) independent colony formation (EEC) and erythropoietin level for diagnosis of PV and assessment of treatment efficiency. Increased PRV-1 expression was found in 37 out of 46 patients diagnosed with PV (80%), in 4 out of 15 patients diagnosed with essential thrombocythemia (ET) (27%) and in 4 out of 8 patients with chronic idiopathic myelofibrosis (CIMF) (50%), and increased PRV-1 expression plus EEC formation was observed in 19 of 36 examined MPD patients indicating the superiority of PVSG and WHO bone marrow criteria for the diagnosis of ET, PV and CIMF. We could confirm a very high sensitivity, specificity and utility of the Jak2(V617F) mutation for differential diagnosis between PV and SE. Spontaneous EEC, serum EPO levels, PRV-1 expression was evaluated in 22 PV patients who carried the Jak2(V617F) mutation. A concordance of increased PRV-1 expression and presence of Jak2(V617F) mutation in 19/22 (85%); of increased PRV-1/Jak2/EEC in 14/22 (63%); and of Jak2/PRV-1/EEC/low Epo level in 10/22 (45%) patients was found indicating the superiority of the presence of Jak2(V617F) mutation for the diagnosis of PV. IFN-alpha therapy in patients with PV was more effective then hydroxyurea treatment and significantly reduced increased PRV-1 expression together with higher levels of Jak2(V617F) mutation (50-100%) in PV patients treated with hydroxy urea (HU) and lower levels of Jak2(V617F) mutation (35-90%) in PV patients treated with IFN-alpha. Normal PRV-1 expression level was observed in 44% of PV patients who achieved clinical remission and only in 3% of patient who did not. These preliminary observations indicate that the Jak2(V617F) mutation in particular and PRV-1 overexpression appear to be suitable markers for monitoring treatment efficiency in prospective randomised clinical studies comparing pegylated interferon and hydroxyurea in well defined PV patients with a clear indication for cytoreductive therapy.

JAK2(V617F) positive early stage myeloproliferative disease (essential thrombocythemia) as the cause of portal vein thrombosis in two middle-aged women: therapeutic implications in view of the literature

The present study describes portal vein thrombosis (PVT) in two women as the first and single presenting symptom of latent or masked myeloproliferative disease (MPD). Essential thrombocythemia (ET) was suspected by a sustained increase in platelet count (>400 x 10(9)/l) and slight splenomegaly on echogram. ET could be diagnosed by the presence of large platelet in peripheral blood smear, an increase in clustered large megakaryocytes in bone marrow smear and the presence of the JAK2(V617F) mutation. A subsequent biopsy specimen was consistent with the diagnosis of true ET. In patients with a first episode of splanchnic vein thrombosis (SVT), analysis of any venous thrombophilic risk factors as well as a JAK2(V617F) mutation status indicative for MPD is warranted. Administration of heparin followed by oral anticoagulation with vitamin K antagonists is the treatment of choice in patients with SVT. Anticoagulation therapy combined with low-dose aspirin and proper treatment of the MPD is recommended in patients with SVT associated with the JAK2(V617F) mutation.

A unified definition of clinical resistance/intolerance to hydroxyurea in essential thrombocythemia: results of a consensus process by an international working group

A widely accepted definition of resistance or intolerance to hydroxyurea (HU) in patients with essential thrombocythemia (ET) is lacking. An international working group (WG) was convened to develop a consensus formulation of clinically significant criteria for defining resistance/intolerance to HU in ET. To this aim, an analytic hierarchy process (AHP), a multiple-attribute decision-making technique, was used. The steps consisted of selecting the candidate criteria for defining resistance/intolerance; identifying the motivations that could influence the preference of the WG for any individual criterion; comparing the candidate criteria in a pair-wise manner; and grading them according their ability to fulfill the motivations. Every step in the model was derived by questionnaires or group discussion. The WG proposed that the definition of resistance/intolerance should require the fulfillment of at least one of the following criteria: platelet count greater than 600,000/micro l after 3 months of at least 2 g/day of HU (2.5 g/day in patients with a body weight over 80 kg); platelet count greater than 400,000/micro l and WBC less than 2500/micro l or Hb less than 10 g/dl at any dose of HU; presence of leg ulcers or other unacceptable muco-cutaneous manifestations at any dose of HU; HU-related fever.

Current diagnostic criteria for the chronic myeloproliferative disorders (MPD) essential thrombocythemia (ET), polycythemia vera (PV) and chronic idiopathic myelofibrosis (CIMF)

The clinical criteria for the diagnosis of essential thrombocythemia (ET) according to the polycythemia vera study group (PVSG) do not distinguish between ET and thrombocythemia associated with early stage PV and prefibrotic chronic idiopathic myelofibrosis (CIMF). The clinical criteria of the PVSG for the diagnosis of polycythemia vera (PV) only detects advanced stage of PV with increased red cell mass. The bone marrow criteria of the World Health Organization (WHO) are defined by pathologists to explicitly define the pathological criteria for the diagnostic differentiation of ET, PV, and prefibrotic and fibrotic CIMF. As the clinical PVSG and the pathological WHO criteria show significant shortcomings, an updated set of European Clinical and Pathological (ECP) criteria combined with currently available biological and molecular markers are proposed to much better distinct true ET from early PV mimicking ET, to distinguish ET from thrombocythemia associated with prefibrotic CIMF, and to define the various clinical and pathological stages of PV and CIMF that has important therapeutic and prognostic implications. Comparing the finding of clustered giant abnormal megakaryocytes in a representative bone marrow as a diagnostic clue to MPD, the sensitivity for the diagnosis of MPD associated with splanchnic vein thrombosis was 63% for increased red cell mass, 52% for low serum EPO level, 72% for EEC, and 74% for splenomegaly indicating the superiority of bone marrow histopathology to detect masked early and overt MPD in this setting. The majority of PV and about half of the ET patients have spontaneous EEC, low serum EPO levels and PRV-1 over-expression and are JAK2 V617F positive. The positive predictive value for the diagnosis of PV of spontaneous growth of endogenous erythroid colonies (EEC) of peripheral blood (PB) and bone marrow (BM) cells is about 80-85% when either PB or BM EEC assays, and up to 94% when BM and PB EEC assays were performed. The diagnostic impact of low serum EPO levels (ELISA assay) in a large study of 186 patients below the normal range (<3.3 IU/l) had a sensitivity specificity and positive predictive value of 87%, 97% and 97.8%, respectively, for the diagnosis of PV. There is a significant overlap of serum EPO levels in PV versus control and controls versus SE. The specificity of a JAK2 V617F PCR test for the diagnosis of MPD is high (near 100%), but only half of ET and MF (50%) and the majority of PV (up to 97%) are JAK2 V617F positive. The use of biological markers including JAK2 V617 PCR test, serum EPO, PRV-1, EEC, leukocyte alkaline phosphatase score and peripheral blood parameters combined with bone marrow histopathology has a high sensitivity and specificity (almost 100%) to diagnose the early and overt stages of ET, PV and CIMF in JAK2 V617F positive and negative MPDs.

[From gene to disease; primary erythermalgia--a neuropathic disease as a consequence of mutations in a sodium pump gene]

Primary erythermalgia is a rare autosomal dominant inherited disorder characterized by recurrent attacks of red, warm and painful burning extremities. The gene involved in primary erythermalgia, SCN9A, encodes for a voltage dependent sodium channel alpha subunit (NaV1.7). NaV1.7 is located in dorsal root ganglions and in nociceptive peripheral neurons. It has been hypothesized that mutations lead to a gain of function and hyperexcitability of peripheral sensory neurons contributing to symptoms in primary erythermalgia.

Among inflammation and coagulation markers, PAI-1 is a true component of the metabolic syndrome

OBJECTIVE

To investigate whether leukocyte count, fibrinogen, von Willebrand factor (vWF) and plasminogen activator inhibitor-1 activity (PAI-1) are increased in subjects with the metabolic syndrome as defined by the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) and the World Health Organisation (WHO).

DESIGN

Cross-sectional study.

SUBJECTS

A total of 520 overweight and obese subjects: 379 women and 141 men, visiting the weight management clinic of a University Hospital.

SUBJECTS AND MEASUREMENTS

Waist circumference, triglycerides, HDL cholesterol, blood pressure and fasting glucose were determined, and the presence or absence of the metabolic syndrome according to the NCEP-ATPIII criteria was assessed. In 349 subjects, data on the waist-to-hip ratio (WHR) and albumin excretion rate were available and the WHO criteria were applied. Insulin resistance was defined using the HOMA-IR index.

RESULTS

Subjects with the metabolic syndrome according to the NCEP-ATPIII criteria had significantly higher levels of leukocyte count (P < 0.001) and PAI-1 (P < 0.001), while no significant differences were found for fibrinogen or vWF (P > 0.05). Using the WHO criteria, similar results were found except for vWF, where higher levels were found in subjects with the metabolic syndrome. When subjects were classified according to the number of components of the metabolic syndrome, levels of leukocyte count, vWF and PAI-1 activity were significantly different (P < 0.05). In logistic regression analysis PAI-1, gender and leukocyte count were independent determinants of the metabolic syndrome (P < 0.001).

CONCLUSION

Evidence for being a true component of the metabolic syndrome is strong for PAI-1, less for leukocyte count and weak for vWF and fibrinogen.

A critical appraisal of non-invasive diagnosis and exclusion of deep vein thrombosis and pulmonary embolism in outpatients with suspected deep vein thrombosis or pulmonary embolism: how many tests do we need?

The requirement for a safe diagnostic strategy should be based on an overall posttest incidence of venous thromboembolism of less than 1% during 3 month follow-up. Compression ultrasonography (CUS) has a negative predictive value (NPV) of 97% to 98% indicating the need of repeated CUS testing. Serial CUS testing is safe but you have to repeat 100 CUS to find 1 or 2 CUS positive for deep vein thrombosis (DVT), which is not cost-effective indicating the need to improve the diagnostic work-up of DVT by the use of clinical score assessment and D-dimer testing. The combination of a less sensitive D-dimer test (SimpliRed) and low clinical score does not, whereas the combination of a sensitive D-dimer test (ELISA VIDAS or Tinaquant) and low clinical score does safely exclude DVT without the need of CUS. The combination of a first negative CUS and a negative less sensitive D-dimer test (SimpliRed) or a sensitive ELISA D-dimer at a higher cut off level of 1,000 ng/ml safely excludes DVT with a NPV of > 99% without the need to repeated CUS in about 60%. The sequential use of a sensitive D-dimer and clinical score assessment will safely reduce the need for CUS testing by 40% to 60%. Large prospective outcome studies demonstrate that one negative examination with complete duplex color ultrasonography (CCUS) of the proximal and distal veins of the affected leg with suspected DVT is safe to withhold anticoagulant treatment with a NPV of 99.5%. This indicates that CCUS is equal or superior to serial CUS or the combined use of clinical score, D-dimer testing and CUS. Pulmonary angiography is the gold standard for segmental pulmonary embolism (PE) but not for subsegmental PE. A normal perfusion lung scan and a normal rapid ELISA VIDAS D-dimer test safely exclude PE. Helical spiral CT detects all clinically relevant PE and a large number of alternative diagnoses in symptomatic patients with a non-diagnostic ventilation perfusion scan (VP-scan) or a high probability VP-scan. Single-slice helical CT as the primary diagnostic test in patients with suspected PE in 5 retrospective studies and in 3 prospective management studies indicate that the NPV of a normal helical spiral CT, a negative CUS of the legs together with a low or intermediate pretest clinical probability is 99%. Helical spiral CT can replace both the VP-scan and pulmonary angiography to safely rule in and out PE. The combination of clinical assessment, a rapid ELISA VIDAS D-dimer followed by CUS will reduce the need for helical spiral CT by 40% to 50%.

Thrombophilia and venous thromboembolism. International consensus statement. Guidelines according to scientific evidence

Thrombophilia is the term now used to describe predisposition to increased risk of venous and occasionally arterial thromboembolism due to hematological abnormalities. It can be a multifactorial disorder where congenital defects of anticoagulant or procoagulant factors may be combined with acquired hematological abnormalities. It should be considered in patients with a documented unexplained thrombotic episode or a positive family history. The aim of this document is to provide guidelines for investigation and management of patients with thrombophilia in the presence or absence of venous thromboembolism (VTE).

Non-invasive diagnosis of pulmonary embolism, anno 2005

Pulmonary angiography is the gold standard for segmental pulmonary embolism (PE) but no longer for subsegmental PE, because the inter-observer agreement for angiographically documented subsegmental PE is only 60%. Two non-invasive tools exclude PE with a negative predictive value of >99% : a normal perfusion lung scan and a normal rapid ELISA VIDAS D-dimer test. The positive predictive value is 85 to 88% for a high probability ventilation-perfusion lung scan (VP-scan) and >95% for helical spiral CT. The prevalence of PE in management studies of symptomatic patients with a non-diagnostic VP-scan is 20 to 24%. Helical spiral CT detects all clinically relevant PE and a large number of alternative diagnoses in symptomatic patients with a non-diagnostic VP-scan or a high probability VP-scan. Single-slice helical CT as the primary diagnostic test in patients with suspected PE in three retrospective studies and in two prospective management study indicate that the negative predictive value of a normal helical spiral CT, a negative compression ultrasonography of the legs (CUS) together with a low or intermediate pre-test clinical probability is >99%. Therefore, helical spiral CT can replace both the VP-scan and pulmonary angiography to safely rule in and out PE. The combination of clinical assessment, a rapid ELISA VIDAS D-dimer followed by CUS will reduce the need for helical spiral CT by 40 to 50%.

Diagnosis of deep vein thrombosis: how many tests do we need?

The requirement for a safe diagnostic strategy should be based on an overall post-test incidence of venous thromboembolism (VTE) of less than 1% during 3 month follow-up. Compression ultrasonography (CUS) has a negative predictive value (NPV) of 97 to 98% indicating a post-CUS incidence of deep vein thrombosis (DVT) of 2 to 3%. A post-CUS DVT incidence of 3% implicates that 90 to 120 DVTs per 1 million inhabitants will be overlooked each year indicating the need to improve the diagnostic work-up of DVT as much as possible. The qualitative D-dimer test (SimpliRed) has a sensitivity of 82 to 89% and a negative predictive value of 94 to 95% indicating a 5 to 6% post-test incidence of DVT, which is not sensitive enough for venous thrombosis exclusion. The post-test DVT incidence could be reduced from 3.2% to 0.6% in one study and from 11% to 2% in another study by the combination of a normal CUS and low clinical score and from 4.5% to 1.6% by the combination of low clinical score and a negative SimpliRed test in one study. The combination of a negative CUS and a negative SimpliRed test reduced the post-test incidence of DVT from 2.6% to < 1% or even < 1% in two management studies without the need of a repeated CUS on the basis of which anticoagulant therapy can safely be withheld. The rapid quantitative turbidimetric D-dimer assay (Tinaquant) has a sensitivity and a negative predictive value (NPV) of 97.7% with a 2.3% post-test incidence of DVT. The combination of a normal Tinaquant D-Dimer test result plus a low to moderate clinical score reduces the post-test incidence of DVT from 2.3 to 0.6% without the need of CUS testing in 29% of patients with suspected DVT. The rapid ELISA VIDAS D-dimer assay has a sensitivity and NPV of 98.6 and 99.5% in two management studies for the exclusion of DVT irrespective of clinical score. The combination of a normal ELISA VIDAS D-Dimer test with clinical score assessment will reduce the post-test DVT incidence of less than 0.5% and the need for CUS testing by 40 to 50%. It is concluded that the sequential use of a rapid quantitative D-dimer test, clinical score and CUS appears to be safe and the most cost-effective diagnostic work-up of DVT.

Platelet-mediated microvascular inflammation and thrombosis in thrombocythemia vera: a distinct aspirin-responsive arterial thrombophilia, which transforms into a bleeding diathesis at increasing platelet counts

Erythromelalgia is the main, pathognomonic and presenting symptom in patients with essential thrombocythemia and thrombocythemia associated with polycythemia vera. Complete relief from erythromelalgic and acrocyanotic pain is obtained with the cyclooxygenase inhibitors aspirin and indomethacin, but not with sodiumsalicylate, dipyridamol, sulfinpyrozone and ticlopedine. Thus, cyclooxygenase metabolites are necessary for erythromelalgia to develop. Local platelet consumption in erythromelalgic areas became evident by the demonstration of arteriolar fibromuscular intimal proliferation and occlusions by platelet-rich thrombi in skin biopsies, by the findings of shortened platelet survival times, significant higher levels of platelet activation markers beta-thromboglobulin, thrombomoduline and increased urinary thromboxane B2 excretion in thrombocythemia patients suffering from erythromelalgia. Aspirin treatment of erythromelalgia in thrombocythemia patients resulted in the disappearance of the erythromelalgic, thrombotic signs and symptoms, correction of the shortened platelet survival times, and a significant reduction of the increased levels of beta-TG, PF4, TM and urinary TxB2 excretion to normal. Erythromelalgia is frequently preceded or followed by atypical transient neurologic, ocular or coronary ischemic symptoms, which specifically respond to low-dose aspirin or reduction of platelet counts to normal. The broad spectrum of acropareshesias, erythromelalgia and acrocyanotic ischemia together with the episodic and transient atypical TIAs and ocular or coronary ischemic symptoms are caused by spontaneous activation and aggregation of hypersensitive platelets in the end-arterial microvasculature involving the peripheral, cerebral and coronary circulation of thrombocythemia patients. These microvascular circulation ischemic disturbances in thrombocythemia vera already occur at platelet counts in excess of 400 x 10(9) l(-1). Low-dose aspirin is highly effective and safe in the cure and prevention of thrombotic and ischemic events and does not elicit bleedings at platelet counts below 1000 x 10(9) l(-1). Spontaneous hemorrhages usually occur at very high platelet counts far in excess of 1000 x 10(9) l(-1) (HT) due to an acquired von Willebrand factor deficiency at increasing platelet counts. At platelet counts between 1000 and 2000 x 10(9) l(-1), thrombosis and bleeding (ETT and HT) frequently occur in sequence or paradoxically and low-dose aspirin does prevent thrombotic complications but aggravates or may elicit bleeding symptoms. Reduction of the platelet count to below 1000 x 10(9) l(-1) by platelet lowering agents usually results in the disappearance of the bleeding tendency and improvement of the von Willebrand syndrome, but the thrombotic tendency persists as long as platelet counts are above the upper limit of normal.

Non-invasive exclusion and diagnosis of pulmonary embolism by sequential use of the rapid ELISA D-dimer assay, clinical score and spiral CT

Pulmonary angiography is the gold standard for segmental pulmonary embolism (PE) but no longer for its subsegmental PE, because the inter-observer agreement for angiographically documented subsegmental PE is only 60%. Two non-invasive tools exclude PE with a negative predictive value of > 99%: a normal perfusion lung scan and a normal rapid ELISA VIDAS D-dimer test. The positive predictive value of a high probability ventilation-perfusion lung scan (VP-scan) is only 85% to 87%. The combination of a low clinical score and a non-diagnostic VP-scan safely exclude PE without the need of angiography. The prevalence of PE and that of an alternative diagnosis in symptomatic patients with a non-diagnostic VP-scan are 10% to 20% and 30% to 45%, respectively. Helical spiral computed tomography (CT) detects all clinically relevant PE and a large number of alternative diagnoses in symptomatic patients with a non-diagnostic or high probability VP-scan. The positive predictive value of the spiral CT is > 95%. Single-slice helical CT as the primary diagnostic test in patients with suspected PE in retrospective outcome studies and in prospective multicenter management studies indicate that the negative predictive value of a negative spiral CT preceded or followed by a negative compression ultrasonography (CUS) is > 99%. Therefore, a helical spiral CT can replace both the VP-scan and pulmonary angiography to safely rule in and out PE. A negative rapid ELISA VIDAS D-dimer test result will reduce the need for helical spiral CT by 25% to 35%.

Aspirin-responsive painful red, blue, black toe, or finger syndrome in polycythemia vera associated with thrombocythemia

Five patients with red, purple blue, or black toes or fingers due to thrombocythemia associated with polycythemia vera (polycythemia and thrombocythemia vera) in four and essential thrombocythemia (thrombocythemia vera) in one are described. The microvascular erythromelalgic syndrome of thrombocythemia was overlooked and progressed to cold blue swollen and painful fingers or black toes in three patients with polycythemia and thrombocythemia vera due to arteriographically documented occlusions of digital or large peripheral arteries with no evidence of preexistent atherosclerotic vascular disease. Concomitant erythromelalgia of the hand palm could be confirmed by the histopathological findings of arteriolar thrombotic lesions in the reticular dermis in two patients with polycythemia and thrombocythemia vera. The increased hematocrit in the presented patients with polycythemia and thrombocythemia vera contributed to the progression of the microvascular syndrome of thrombocythemia to major occlusive ischemic events of the extremities. Standard therapy with oral anticoagulants and reduction of the hematocrit to normal by bloodletting did not affect the platelet-mediated microvascular erythromelalgic, ischemic symptoms in the patients with polycythemia vera because thrombocythemia vera persisted. Complete relief of pain and restoration of the ischemic acral circulation disturbances in patients with thrombocythemia vera or thrombocythemia associated with polycythemia vera in maintained remission by bloodletting could be obtained by long-term treatment with low-dose aspirin.

Bilateral adrenal swelling as a cause of chest, back, and upper abdominal pain in essential thrombocythemia and polycythemia vera is due to microvascular ischemic thrombosis rather than to hemorrhage

Bilateral massive adrenal swelling (BAS) on computed tomography (CT) scan with no enhancement after injection of intravenous contrast media has been observed in two completely different clinical settings. On the one hand, BAS is the result of ischemic necrosis and subsequent hemorrhagic infarction in patients with sepsis and hypotension in critically ill situations. On the other hand, BAS is the result of microvascular thrombosis, ischemia, and secondary inflammatory swelling in the setting of thrombotic conditions such as antiphospholipid syndrome (APS), heparin-induced thrombocytopenia and thrombosis (HITT), and thrombocythemia. In this study we present evidence that the etiology of unilateral or BAS in reported cases of essential thrombocythemia (ET) and polycythemia vera (PV) is similar to the etiology of microvascular circulation disturbances in thrombocythemia caused by platelet-mediated inflammation and thrombosis in the peripheral, cerebral, and/or coronary endarterial microvascular circulation.

Distal deep venous thrombosis in a hemophilia A patient with inhibitor and severe infectious disease, 18 days after recombinant activated factor VII transfusion

We describe a 38 year old hemophilia A patient with a factor VIII inhibitor who was admitted to our Hematology Department in January 2001 with a seriously infected and bleeding perianal ulcer. To treat infection and bleeding the patient received broad spectrum antibiotics and recombinant activated factor VII (rFVIIa) (Novoseven(R)) for about 1 month (see detailed time of administration and dosing schedule of rFVIIa further in text). Eighteen days after his last rVIIa infusion the patient developed an ultrasound proven right calf vein thrombosis. In the whole period of admission, preceding the thrombotic event the patient biologically showed a picture of severe systemic inflammatory disease as indicated by persistent increased levels of D-dimer and fibrinogen (table). It is an interesting point of discussion whether the calf thrombosis was provoked as a consequence of rFVIIa infusion (with symptoms 18 days after the last infusion) or as a consequence of long-standing immobilization and severe inflammatory disease immobilization and severe infection are conditions well known for promoting venous thromboembolic disease.

Comparison of antiplatelet effect of loading dose of clopidogrel versus abciximab during coronary intervention

Randomized clinical trials have evidently shown that the addition of thienopyridines or abciximab to standard aspirin results in a significant reduction of ischaemic complications after coronary stent implantation. A head-to-head comparison of these antithrombotic drug regimens during coronary intervention is, however, lacking, and this was the main aim of the present study. Thirty-nine patients with angina pectoris who were scheduled for coronary stent implantation were assigned to either group 1 (160 mg aspirin + 500 mg ticlopidine post-stent), group 2 (160 mg aspirin + abciximab + 500 mg ticlopidine post-stent) or group 3 (160 mg aspirin + loading dose (375/450 mg) clopidogrel pre-stent and 75 mg clopidogrel post-stent). A loading dose of 450 mg clopidogrel was found to be more effective than the standard loading dose of 375 mg. Platelet aggregation induced by 4 micromol/l adenosine diphosphate (ADP) was assessed in samples collected before intervention and 10 min, 4 h and 20 h after intervention. Before intervention, a moderate antiplatelet effect because of aspirin intake was observed (ADP aggregation level, +/- 50%) in all study groups. After intervention, platelet aggregation tended to be enhanced in group 1 while it was strongly inhibited in the groups pre-treated with clopidogrel or abciximab: ADP induced an aggregation level early after intervention of 60 +/- 12% in group 1 (ticlopidine post-stenting) versus 30 +/- 10% in group 3 (loading dose clopidogrel) versus 3 +/- 6% in group 2 (abciximab). Abciximab achieved a more complete inhibition of aggregation than clopidogrel (P = 0.007). The overall complication rate was low with only one major bleeding and one death due to side-branch occlusion with re-infarction occurring, both in the abciximab group. Platelet aggregation during coronary intervention is strongly inhibited by both abciximab and by high loading dose of clopidogrel. Although abciximab showed a stronger antiplatelet effect than clopidogrel, it remains to be established whether this ex vivo superiority of abciximab also translates into an overall clinical benefit in patients with elective stent implantation.

Exclusion and diagnosis of deep vein thrombosis in outpatients by sequential noninvasive tools

Phlebography is the reference gold standard for the diagnosis of deep vein thrombosis (DVT), but due to its invasive nature and associated side effects it has been replaced by compression ultrasonography (CUS). Patients suspected of DVT are subjected to leg vein CUS that actually confirms DVT in only 16 to 28% of outpatients in large prospective management studies. CUS has a high positive predictive value of more than 98% for proximal DVT but usually misses calf vein thrombosis. Its negative predictive value for proximal DVT is about 97-98%, on the basis of which repeated scanning at day 7 after a negative first CUS (serial CUS) in outpatients with a first suspicion of DVT is advocated. Serial ultrasonography is costly and can be simplified and improved by the addition of clinical score and D-dimer testing. The safe exclusion of DVT by a rapid sensitive D-dimer test in combination with clinical score and/or CUS requires a negative predictive value of >99%. The negative predictive value for DVT is determined by the sensitivity of the rapid ELISA D-dimer test and the prevalence of DVT in subgroups of outpatients suspected of the condition. The prevalence of DVT in outpatients with a low, moderate and high clinical score varies widely from 3-10%, 15-30% and >70%, respectively. The combination of a low clinical score (prevalence DVT 3-5%) and a negative rapid ELISA D-dimer alone test will have a very high negative predictive value of >99.9% to exclude DVT without the need of CUS testing. The combination of a negative CUS and a negative rapid ELISA D-dimer test safely excludes DVT in patients with suspected DVT irrespective of the clinical score. The combination of a negative CUS, a low clinical score and a positive ELISA D-dimer but <1000 ng/ml excludes DVT with a negative predictive value of >99% without the need to repeat CUS. Patients with a negative CUS, scan but a positive ELISA D-dimer, and a moderate or high clinical score are still at risk with a probability of DVT of 3-5% and 20-30%, respectively and are thus candidates for repeated ultrasound scanning. The rapid ELISA D-dimer first followed by risk-based no, single or repeated CUS will be the most cost-effective strategy.

Acquired von Willebrand syndromes: clinical features, aetiology, pathophysiology, classification and management

Acquired von Willebrand syndrome (AVWS) associated with hypothyroidism is of type I, results from a decreased synthesis of factor VIII and von Willebrand factor (VWF), responds to desmopressin with normal half-life times for factor VIII and VWF parameters, and disappears after treatment with I-thyroxine. AVWS type I or III, which occurs in a minority of patients with Wilms' tumour in the complete absence of an inhibitor against VWF and no absorption of factor VIII or VWF onto nephroblastoma cells, responds to chemotherapy and/or tumour resection. Hyaluronic acid produced by nephroblastoma cells may be the causative factor in atypical AVWS in Wilms' tumour. AVWS associated with thrombocythaemia of various myeloproliferative disorders is characterized by normal factor VIII and von Willebrand factor antigen (VWF: Ag) levels and a selective deficiency of functional ristocetin co-factor activity (VWF: RCo) and collagen-binding activity (VWF: CBA). AVWS type II in thrombocythaemia is caused by a platelet-dependent proteolysis of large VWF multimers, given the inverse relationship between platelet count and large VWF multimers in plasma and specific increases in the number of proteolytic VWF fragments in plasma. The laboratory findings of AVWS associated with systemic lupus erythematosus or IgG benign monoclonal gammopathy are characterized by a prolonged bleeding time and activated partial thromboplastin time, decreased or absent ristocetin-induced platelet activity, low to very low levels of factor VIII coagulant activity (mean 15%), VWF: Ag (mean 10.7%) and VWF: RCo (mean 6.2%), and a type II multimeric pattern of VWF. Neutralizing and non-neutralizing anti-VWF autoantibodies, usually IgG, have been detected in patient plasma either free or tightly bound to the intermediate and high molecular weight VWF factor VIII particles. The bound auto antibody-antigen complex is rapidly cleared from the circulation, resulting in low levels of factor VIII, VWF parameters as documented by a poor response to desmopressin and VWF factor VIII concentrate. High-dose intravenous immunoglobulin transiently corrects the factor VIII coagulant and VWF levels, lasting for a few weeks in AVWS type II associated with systemic lupus erythematosus or IgG benign monoclonal gammopathy. Prednisolone is effective in AVWS associated with autoimmune disorder. Prednisolone and chemotherapy will not affect AVWS associated with IgG benign monoclonal gammopathy because the monoclonal IgG protein remains to act as an anti-VWF autoantibody. An absorption of VWF to malignant cells has been documented in a few patients with various lymphoproliferative disorders or adrenal carcinoma and suggested to result in a depletion of VWF. The clinical picture of AVWS associated with early-stage IgG multiple myeloma, chronic lymphocytic leukaemia or non-Hodgkin's lymphoma without a paraprotein or no detectable underlying disorder is similar to that of AVWS type II in IgG benign monoclonal gammopathy but poorly documented with regard to the underlying immune mechanism of AVWS. The mechanical destruction of large VWF multimers may be of relevance in conditions in which the shear rate of flowing blood is increased, as may occur in cases of aortic stenosis, other heart valve defects or stenosed vessels. Drug-induced AVWS has been described in association with the use of pesticides valproic acid, ciprofloxacin, griseofulvin, tetracycline, thrombolytic agents and hydroxyethyl starch.

The primary erythermalgia-susceptibility gene is located on chromosome 2q31-32

Primary erythermalgia is a rare disorder characterized by recurrent attacks of red, warm, and painful hands and/or feet. The symptoms are generally refractory to treatment and persist throughout life. Five kindreds with multiple cases of primary erythermalgia were identified, and the largest was subjected to a genomewide search. We detected strong evidence for linkage of the primary erythermalgia locus to markers from chromosome 2q. The highest LOD score (Z) was obtained with D2S2330 (Z(max) = 6.51). Analysis of recombination events identified D2S2370 and D2S1776 as flanking markers, on chromosome 2q31-32. This defines a critical interval of 7.94 cM that harbors the primary erythermalgia gene. Affected members within the additional families also shared a common haplotype on chromosome 2q31-32, supporting our linkage results. Identification of the primary erythermalgia gene will allow a better clinical classification of this pleomorphic group of disorders.

Strategies for the safe and effective exclusion and diagnosis of deep vein thrombosis by the sequential use of clinical score, D-dimer testing, and compression ultrasonography

Patients with suspected deep vein thrombosis (DVT) are subjected to leg vein compression ultrasonography (CUS) that confirms DVT in only 20 to 30% of patients. A positive CUS is consistent with DVT irrespective of clinical score. The sequential use of a simple clinical score assessment, a rapid sensitive enzyme-linked immunosorbent assay (ELISA) D-dimer test and CUS to safely exclude DVT is promising. The clinical score is a validated clinical model of complaints, signs, and symptoms, on the basis of which a pretest clinical probability for DVT can be estimated as low, moderate, and high. The safe exclusion of DVT by a rapid sensitive D-dimer test in combination with clinical score or CUS necessitates a negative predictive value of more than 99%. The negative predictive value for DVT is determined by the sensitivity of the rapid ELISA D-dimer test and the prevalence of DVT in subgroups of outpatients with suspected DVT. The prevalence of DVT in outpatients with a low, moderate, and high clinical score varies widely from 3 to 10%, 15 to 30% and more than 70%, respectively. A negative rapid ELISA D-dimer and a low clinical score (prevalence DVT 3 to 5%) will have a very high negative predictive value of more than 99.5% to exclude DVT without the need of CUS testing. A negative ELISA D-dimer test and a first-negative CUS safely exclude DVT in patients with a moderate clinical score with a negative predictive value of more than 99.5%, therefore obviating the need to repeat CUS. The use of a rapid ELISA D-dimer testing in patients with a high clinical score is not recommended. A negative CUS, a low clinical score, and a positive ELISA D-dimer, even less than 1000 ng/mL exclude DVT with a nega tive predictive value of more than 99%. Patients with a negative CUS, but a positive ELISA D-dimer, and a moderate or high clinical score have a probability of DVT of 3 to 5% and 20 to 30%, respectively, and are thus candidates for repeated CUS testing. The proposed sequential use of the clinical score assessment, a rapid ELISA D-dimer test, and CUS will be the most cost-effective diagnostic strategy for DVT because of a significant reduction of CUS examinations and gain of time for the patient and physician in charge.

Acquired von Willebrand syndrome type 1 in hypothyroidism: reversal after treatment with thyroxine

In 16 cases, acquired von Willebrand syndrome (AvWS) and hypothyroidism have been described that occur with each other: 15 women and one man, at a mean age of 32 years, range, 13 to 82 years of age. Activated partial thromboplastin time (APTT) was normal in six patients, and five patients had factor VIII concentration (factor VIIIc) levels in excess of 60%. The bleeding time was prolonged in nine of 13 evaluable patients. Activated partial thromboplastin time was prolonged in seven patients, and five of these had factor VIIIc levels between 18 and 45%, with two patients having levels in excess of 60%. A deficiency of other coagulation factors, including factor VII, V, IX, and X, caused by a generalized diminution in protein synthesis in hypothyroidism, may have contributed to the prolongation of the APTT. The AvWS was very likely type 1 in all cases because of a normal von Willebrand factor antigen/ristocetin cofactor (vWF Ag/RCF) ratio. Acquired von Willebrand syndrome was documented via cross immunoelectrophoresis in three patients and via multimeric analysis of vWF in six patients. A definite diagnosis of AvWS type I has to be confirmed by a normal response to 1-desamino-8-D-arginine vasopressin (DDAVP). Treatment of hypothyroidism with thyroxine was associated with the disappearance of the AvWS and the bleeding diathesis. Decreased factor VIIIc, vWF Ag and vWF RCF levels (50%, 33%, and 36% respectively) before thyroxine treatment increased to normal values (97%, 93%, and 107% respectively) after treatment. The absence of bleeding, or mild bleeding, symptoms, in relation to those more commonly recognized with hypothyroidism, has led to the complication of acquired vWF deficiency being underdiagnosed. Acquired von Willebrand syndrome type I should be considered whenever hypothyroidism is diagnosed and thyroid biopsy or surgery is contemplated. The complete relief of AvWS via treatment of hypothyroidism with thyroxine is the final proof of this association and causal relationship.

Acquired von Willebrand syndrome in systemic lupus erythematodes

Acquired von Willebrand syndrome (AvWS) in systemic lupus erythematodes (SLE) is caused by autoantibodies directed against the circulating von Willebrand factor (vWF)/factor VIII (FVIII) complex. The autoantibody-vWF/FVIII antigen complex is cleared rapidly from the circulation, leading to a moderate to severe quantitative and qualitative deficiency of both vWF and FVIIIc. Consequently, AvWS in SLE is featured by a prolonged bleeding time and normal platelet count, a prolonged activated partial thromboplastin time (APTT) and normal prothrombin time (PT), decreased or absent ristocetin-induced platelet aggregation (RIPA), and type II vWF deficiency on multimeric analysis of the vWF protein. Acquired von Willebrand syndrome type II in SLE responds poorly to 1-desamino-8-D-arginine vasopressin (DDAVP) and FVIII concentrate, but responds transiently well to high-dose gammaglobulin given intravenously. All reported cases of AvWS in SLE were cured by appropriate treatment of the underlying autoimmune disease with prednisone or immunosuppression.

Carboxypeptidase U at the interface between coagulation and fibrinolysis

In 1988, Hendricks et al. first reported on the presence of carboxypeptidase U (U refers to the unstable nature of the enzyme) in human serum. One decade later, the importance of carboxypeptidase U (CPU) in the regulation of fibrin clot dissolution is well documented. CPU circulates in plasma as an inactive zymogen, proCPU, that is converted to its active form during coagulation and fibrinolysis. CPU cleaves off C-terminal lysine residues exposed on fibrin partially degraded by the action of plasmin. Because these C-terminal lysine residues are important for upregulating the fibrinolytic rate, CPU thus slows down fibrinolysis.

Effectiveness of anagrelide in the treatment of symptomatic patients with essential thrombocythemia

We prospectively evaluated the effect of anagrelide on platelet counts and the clinical manifestations of microvascular circulation disturbances in 17 newly diagnosed patients with essential thrombocythemia. Ten patients had symptoms related to thrombocythemia, eight at the time of starting anagrelide treatment. The platelet counts before anagrelide treatment and during maintained remission of essential thrombocythemia by anagrelide were 980 (range, 610-2030) and 378 (range, 212-546) x 10(9)/L, respectively. Spontaneous platelet aggregation was found in 6 patients (35%), which disappeared on remission of essential thrombocythemia in five cases (P = 0.02). Essential thrombocythemia-related microvascular thrombotic and hemorrhagic symptoms disappeared with the normalization of platelet count in all cases during maintained remission of essential thrombocythemia by long term continuous anagrelide treatment with a follow-up period of between 2 and 6 years. However, ET-related symptoms reappeared in three patients, coinciding with increased platelet count up to 600 x 10(9)/L caused by anagrelide dose reduction. We conclude that reduction of increased platelet to normal (< 400 x 10(9)/L) in symptomatic patients with essential thrombocythemia through use of maintained anagrelide treatment is associated with the disappearance of spontaneous platelet aggregation and the complete relief of thrombotic and hemorrhagic manifestations.

Acquired hemophilia A in women postpartum: clinical manifestations, diagnosis, and treatment

Acquired hemophilia A in women postpartum is diagnosed by a prolonged activated partial thromboplastin time (APTT), low plasma levels of coagulant factor VIII, and the detection of an inhibitor against factor VIII in the Bethesda assay. Effective treatment of bleeding symptoms should be based upon the clinical situation and depends on the inhibitor characteristics against human and porcine factor VIII. Immunosuppression usually does not significantly affect the disappearance of the factor VIII inhibitor antibody. The natural history of acquired hemophilia postpartum is independent of immunosuppressive treatment and featured by spontaneous disappearance of the inhibitor against factor VIII in the majority of cases.

Spontaneous proliferative megakaryocytopoiesis and platelet hyperreactivity in essential thrombocythemia: is thrombopoietin the link?

Essential thrombocythemia (ET) is one of the less rare variants of the chronic myeloproliferative disorders (MPD). The present review questions the possible link between spontaneous megakaryocytopoiesis, platelet hyperreactivity, and the occurrence of platelet-mediated vascular manifestations in acquired and hereditary ET. In acquired ET, the role of thrombopoietin (TPO) is crucial to the observed hypermegakaryocytopoiesis, which is characterized by an increased proliferation of megakaryocyte (MK) progenitors, even in conditions of culture without addition of any known megakaryocyte colony-stimulating factors. An increased reactivity of megakaryocyte progenitors to TPO remains to be precisely delineated. A defective clearance of TPO by megakaryocytes and platelets because of a reduced number of TPO receptors is possible. TPO is able to enhance platelet aggregation induced by ADP, thrombin, and collagen. A point mutation in the TPO gene as the cause of increased TPO production in hereditary ET can readily explain both spontaneous megakaryocytopoiesis and platelet-mediated microvascular manifestations simulating the phenotype of acquired ET. Nevertheless, to date, no mutation of the TPO structural gene, as shown in two families with hereditary ET, and no mutations in the TPO receptor have been found in patients with acquired ET. There is good evidence that the microvascular circulation disturbances in ET are caused by intravascular activation and aggregation of hypersensitive platelets, with sludging or occlusion of the endarterial microvasculature. In this process, the generation of platelet-derived products, endothelial cell damage, fibromuscular intimal proliferation, and platelet thrombi are essential and can be inhibited by a platelet-specific regimen of aspirin, thus providing a rationale for using low-dose aspirin as an antithrombotic agent in thrombocythemia. In contrast, the generation of thrombin appears not to be essential for the formation of platelet thrombi, thereby explaining the inefficacy of coumadin derivatives and heparin in the treatment and prevention of microvascular circulation disturbances in hereditary and acquired ET.

Exclusion and diagnosis of pulmonary embolism by a rapid ELISA D-dimer test and noninvasive imaging techniques within the context of a clinical model

A negative rapid ELISA D-dimer test alone in out-patients with a low to moderate clinical probability (CP) on pulmonary embolism (PE) is predicted to safely exclude pulmonary embolism. The combination of a negative rapid ELISA D-dimer test and a low to moderate CP on PE followed by compression ultrasonography (CUS) for the detection of deep vein thrombosis (DVT) is safe and cost-effective as it reduces the need for noninvasive imaging techniques to about 50% to 60% of outpatients with suspected PE. A high probability ventilation-perfusion (VP) scan or a positive spiral CT consistent with PE and the detection of DVT by CUS are currently considered to be clear indications for anticoagulant treatment. Subsequent pulmonary angiography (PA) is the gold standard diagnostic strategy to exclude or diagnose PE in suspected outpatients with a negative CUS, a positive rapid ELISA D-dimer test, and a nondiagnostic VP scan or negative spiral CT to prevent overtreatment with anticoagulants. However, the willingness of clinicians and the availability of resources to perform PA is restricted, a fact that has provided an impetus for clinical investigators to search for alternative noninvasive strategies to exclude or detect venous thromboembolism (VTE). Serial CUS testing for the detection of DVT in patients with a low to moderate CP on PE and a nondiagnostic VP scan or negative spiral CT is predicted to be safe and will reduce the need for PA to less than 10% or even less than 5%. This noninvasive serial CUS strategy restricts the need for invasive PA to a minor group of patients (< 5%) with the combination of a low CP on PE and high probability VP scan or the combination of a nondiagnostic VP scan or negative spiral CT and a high CP on PE. Prospective evaluations are warranted to implement and to validate the advantages and the disadvantages of the various combinations of noninvasive strategies and to compare serial CUS testing versus PA in randomized clinical management studies of outpatients with suspected pulmonary embolism.

Diagnosis and treatment of polycythemia vera and possible future study designs of the PVSG

The present study describes clinicopathological criteria to distinguish the 5 sequential stages proposed by Wasserman et al in the natural history of newly diagnosed PV patients. The European Working Group on MPD (EWG.MPD) extended and modified the PVSG diagnostic criteria of PV by including bone marrow histopathology. From the results of prospective randomized studies in PV it became evident that new clinical trials in previously untreated PV patients should focus on comparing interferon-alpha, a non-leukemogenic approach, versus a potential leukemogenic myelosuppressive treatment modality. Hydroxyurea appears to be the least leukemogenic myelosuppressive agent in long-term prospective clinical PV-studies extending observation periods of more than 10 years. The rational for using IFN-alpha as a first-line treatment option in newly diagnosed PV-patient include its effectiveness to abate constitutional symptoms and to induce a complete remission thereby avoiding phlebotomy, iron deficiency, and macrocytosis associated with hydroxyurea. Moreover IFN-alpha may prevent or delay the development of postpolycythemic myelofibrosis if used early in the course of the disease. Clinicians will be reluctant to postpone the use of hydroxyurea in early stage PV as long as a conservative approach using phlebotomy aiming at a hematocrit below 0.45, plus low-dose aspirin for the control platelet function or anagrelide for the control platelet number is used to keep the patient healthy. Low-dose aspirin will prevent the microvascular thrombotic complications of thrombocythemia associated with PV in remission after phlebotomy, but lacks myelosuppressive activity. Control of megakaryocyte maturation and reduction of platelet production to normal (<400 x 10(9)/l) by relatively low doses of anagrelide will predict a significant reduction of vascular complications in the early stages of PV, may prevent progression to myelofibrosis during follow-up of PV and very probable will postpone the use of hydroxyurea treatment for controlling the platelet count in PV. Large scale randomized clinical trials in PV are proposed, which should aim not only for clinical and hematological response, safety, efficacy, but should also assess toxicity, the need for phlebotomy and whether the development of progressive disease such as splenomegaly, pruritus, myelofibrotic myeloid metaplasia, spent phase, myelodysplasia and acute leukemia can be delayed or prevented by IFN-alpha as compared to a conservative approach of phlebotomy plus low-dose aspirin or anagrelide followed by hydroxyurea when signs of myeloproliferative activity became evident.

Aspirin and platelet-lowering agents for the prevention of vascular complications in essential thrombocythemia

Low-risk essential thrombocythemia patients include patients aged 18 to < 80 years with no vascular risk factor or previous thrombosis, no associated disease, a normal life expectancy, and a platelet count between 400 and 1,000 x 10(9)/L up to 1,500 x 10(9)/L. Asymptomatic essential thrombocythemia patients may be at risk for microvascular circulation disturbances. The indication for low-dose aspirin in asymptomatic essential thrombocythemia patients is uncertain, therefore randomization for aspirin 50 mg versus placebo is recommended. Symptomatic essential thrombocythemia patients with erythromelalgia and its ischemic complications, atypical transient ischemic attacks, minor stroke, visual disturbances and "superficial thrombophlebitis" in the absence of bleeding, vascular risk factors, or vascular disease have a clear indication for aspirin in a regular dose. To determine whether 50 mg/day is as effective as 100 mg/day for the prophylaxis of microvascular circulation disturbances in essential thrombocythemia, a randomized trial comparing low-dose aspirin 50 mg versus 100 mg at platelet counts between 400 and 1,000 up to 1,500 x 10(9)/L is recommended. To address the question whether reduction of the platelet count to normal (< 350 x 10(9)/L) is as effective as low-dose aspirin for the long-term relief of microvascular circulation disturbances, a randomized study comparing low-dose aspirin with the correction of platelet count to normal by anagrelide is recommended. High-risk essential thrombocythemia patients have a clear indication for platelet reductive therapy, including: (a) platelets > 1,500 x 10(9)/L, history of major thrombosis (myocardial infarction, stroke, peripheral occlusive vascular disease), or presence of vascular disease (e.g., arteriosclerosis); (b) history or presence of spontaneous or major bleedings, bleedings elicited by low-dose aspirin for the secondary prevention of vascular complications in essential thrombocythemia at platelet counts < 1500 x 10(9)/L, and side effects of long-term aspirin treatment such as gastritis; and progression from low- to high-risk essential thrombocythemia patients during follow-up or progressive myeloproliferative disease such as significant splenomegaly, myelofibrosis, leukocytosis, etc. To address the question of optimal treatment of high-risk essential thrombocythemia patients, randomization for anagrelide versus interferon at < 65 years of age and anagrelide versus hydroxyurea at an age > 65 years is recommended.

Acquired von Willebrand disease due to increasing platelet count can readily explain the paradox of thrombosis and bleeding in thrombocythemia

The arterial microvascular thrombotic events in thrombocythemia including erythromelalgia, atypical and typical cerebral and ocular transient ischemic attacks, and acute coronary syndromes already occur at platelet counts > 400 x 10(9)/L and are sensitive to low-dose aspirin, which does not elicit bleedings at platelet counts < 1,000 x 10(9)/L. An increasing platelet count in thrombocythemia to above 1,000 x 10(9)/L is accompanied by the acquisition of a von Willebrand factor deficiency due to the loss of intermediate and large von Willebrand factor multimers. The arterial thrombotic condition in thrombocythemia changes into an overt spontaneous bleeding tendency at mean platelet counts of about 2,000 +/- 1,000 x 10(9)/L due to an acquired von Willebrand disease type II with normal values for von Willebrand factor antigen concentration but absence of intermediate and large von Willebrand factor multimers in plasma. At platelet counts between 1,000 and 2,000 x 10(9)/L, thrombosis and bleeding frequently occur in sequence or paradoxically, and low-dose aspirin does prevent thrombotic complications but aggravates or may elicit bleeding symptoms. Reduction of the platelet count < 1,000 x 10(9)/L significantly restores the von Willebrand factor deficiency with the reappearance of the intermediate and some of the large von Willebrand factor multimers and the disappearance of the bleeding tendency, but the thrombotic tendency persists as long as platelet counts are above the upper limit of normal. The acquisition of von Willebrand factor deficiency at increasing platelet counts can readily explain the paradox of thrombosis and bleeding in thrombocythemia and has important clinical implications.

Acquired von Willebrand disease in monoclonal gammapathies: effectiveness of high-dose intravenous gamma globulin

The reported underlying lymphoproliferative disorders associated with acquired von Willebrand disease (AvWD) include benign monoclonal gammapathy, multiple myeloma, Waldenström disease, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and hairy cell leukemia. The AvWD in patients with a monoclonal gammapathy and/or a lymphoproliferative disorder is featured by a prolonged bleeding time, normal platelet count, and a decreased or absent ristocetine-induced platelet aggregation in combination with a prolonged aPTT and normal PT due to low levels of factor VIII/von Willebrand factor (vWF) parameters in the absence of a factor VIII inhibitor in the Bethesda assay. In vitro and vivo experiments consistently showed that the anti-vWF autoantibodies in monoclonal gammapathies cause a rapid clearance of the factor VIII/vWF complex from the circulation after DDAVP and factor VIII/vWF concentrate infusion. Multimeric analysis of the vWF usually show a type II-like AvWD due to the absence of large vWF multimers as the consequence of the rapid clearance of the anti-vWF-factor VIII/vWF complex from the circulation. There is a poor response to intravenous DDAVP and factor VIII/vWF concentrate infusion, but high dose intravenous gamma globulin (1 g/kg for 2 days) usually induces a transient correction of the factor VIII/vWF parameters for 1 to a few weeks.

Exclusion and diagnosis of deep vein thrombosis by a rapid ELISA D-dimer test, compression ultrasonography, and a simple clinical model

The classical clinical signs of deep vein thrombosis (DVT) are unspecific and may be found in several other conditions besides DVT. Therefore, patients suspicious of DVT are subjected to elaborate invasive or noninvasive evidence-based procedures that actually confirm DVT in only 20% to 30% of patients in this setting. However, simple laboratory tests and noninvasive strategies to exclude and diagnose DVT are becoming available in the clinical emergency setting of outpatients. In the presented literature, a sound basis is provided for quantifying clinical judgment for the diagnosis of acute proximal DVT. The number of positive clinical findings at time of first suspicion of DVT appears to correlate directly with the probability of acute proximal DVT. The modified clinical model of Landefeld and Wells for DVT allows reasonable accurate classification of patients into low, moderate, and high probability for suffering DVT. The rapid automated enzyme-linked immunoabsorbant assay (ELISA) VIDAS D-dimer presently available can be rapidly performed in daily practice and emergency situations and is accurate to a high degree, especially in ruling out ongoing venous thromboembolic processes. The sequential use of the rapid ELISA VIDAS D-dimer test and compression ultrasonography in a well-designed clinical setting using a simple clinical model predicts a significant improvement due to a high sensitivity near 100% for the exclusion and diagnosis of DVT in the majority of outpatients with suspect DVT. A prospective decision analysis management study is proposed to exclude and diagnose DVT based on the rapid ELISA VIDAS D-dimer test and compression ultrasonography within the context of a ready-to-use simple clinical model. The proposed simple model of a rational diagnosis of deep vein thrombosis (RADIA DVT) has to be tested in a large multicenter study of more than 1,000 outpatients with suspected DVT. This model would be less expensive, easy to perform, and likely yield a significant simplification and improvement of highly accurate evidence-based exclusion or diagnosis of DVT on the basis of which clear-cut indications of anticoagulation could be appropriately initiated or safely withheld.

Diagnosis, pathogenesis and treatment of the myeloproliferative disorders essential thrombocythemia, polycythemia vera and essential megakaryocytic granulocytic metaplasia and myelofibrosis

According to strict clinical, hematological and morphological criteria, the Philadelphia (Ph) chromosome negative chronic myeloproliferative disorders essential thrombocythemia (ET), polycythemia vera (PV), and agnogenic myeloid (megakaryocytic/granulocytic) metaplasia (AMM) or idiopathic myelofibrosis (IMF) are three distinct disease entities with regard to clinical manifestations, natural history and outcome in terms of life expectancy. As clonality studies have clearly demonstrated that fibroblast proliferation in AMM, as well as in many other conditions such as advanced stages of Ph(+)-essential thrombocythemia, Ph(+)-granulocytic leukemia, and Ph(-)-polycythemia vera, is polyclonal indicating that myelofibrosis is secondary to the megakaryocytic granulocytic metaplasia in these various conditions, AMM is illogically labeled as IMF. As abnormal megakaryocytic granulocytic metaplasia is the essential feature preceding the early prefibrotic stage of AMM, the term essential megakaryocytic granulocytic metaplasia (EMGM) can readily be used to characterize this condition more appropriately at the biological level. Clinical, hematological and morphological characteristics, in particular megakaryocytopoiesis and bone marrow cellularity, reveal diagnostic features, which enable a clear-cut distinction between ET, PV and EMGM or classical IMF. The characteristic increase and clustering of enlarged megakaryocytes with mature cytoplasm and multilobulated nuclei and their tendency to cluster in a normal or only slightly increased cellular bone marrow represent the hallmark of ET. The characteristic increase and clustering of enlarged mature and pleiomorphic megakaryocytes with multilobulated nuclei and proliferation of erythropoiesis in a moderate to marked hypercellular bone marrow with hyperplasia of dilated sinuses are the specific diagnostic features of untreated PV. EMGM, including the early prefibrotic stages as well as the various myelofibrotic stages of classical IMF appear to be a distinct neoplastic dual proliferation of abnormal megakaryopoiesis and granulopoiesis. The histopathology of the bone marrow in prefibrotic EMGM and in classical IMF is dominated by atypical, enlarged and immature megakaryocytes with cloud-like immature nuclei, which are not seen in ET and PV at diagnosis and during follow-up. Myelofibrosis in ET, PV and EMGM is graded into: no reticulin fibrosis (MF0), early reticulin fibrosis (MF1), advanced reticulin sclerosis with minor or moderate collagen fibrosis (MF2) and advanced collagen fibrosis with osteosclerosis (MF3). Myelofibrosis is not a feature of ET at diagnosis and during long-term follow-up. Myelofibrosis may be present in a minority of PV-patients at diagnosis and usually becomes apparent during long-term follow-up in the majority of PV-patients. Myelofibrosis secondary to the abnormal megakaryocytic and granulocytic myeloproliferation constitutes a prominent feature in the majority of EMGM/IMF at time of diagnosis and usually progresses more or less rapidly during the natural history of the disease. Life expectancy is normal in ET, normal during the 1st ten years and compromised during the 2nd ten years follow-up in PV, but significantly shortened in the prefibrotic stage of EMGM as well as in the various myelosclerotic stages of classical IMF. First line treatment options in prospective randomized clinical trials of newly diagnosed MPD-patients are control of platelet function with low-dose aspirin versus reduction of platelet count with anagrelide, interferon or hydroxyurea in ET; control of platelet and erythrocyte counts by interferon alone versus bloodletting plus hydroxyurea on indication in PV; interferon versus no treatment in the early stages of EMGM; a wait and see strategy in the fibrotic stages of EMGM or classical IMF with favorable prognostic factors, and bone marrow transplantation in classical IMF with poor prognostic factors at presentation or during short-term follow-up.

Thromboxane-dependent platelet activation in vivo precedes arterial thrombosis in thrombocythaemia: a rationale for the use of low-dose aspirin as an antithrombotic agent

The clinical course of patients with polycythaemia vera (PV) and essential thrombocythaemia (ET) is frequently complicated by arterial thrombotic events. The pathogenesis is not clearly understood but attributed to abnormalities in platelet function. An increase in platelet thromboxane formation has been described in the majority of asymptomatic patients with thrombocythaemia, probably reflecting spontaneous platelet activation in vivo. In the present study we prospectively investigated whether an increase in platelet thromboxane formation actually precedes arterial microvascular thrombosis. In addition, we studied the effect of selective inhibition of platelet thromboxane formation on clinical outcome by reinstitution of low-dose aspirin (50 mg/ d). Six ET patients and one PV patient participated in this study. Within 10 d after withdrawal of aspirin, three patients developed arterial microvascular thrombosis of extremities (erythromelalgia), which was preceded by a 3-30-fold increase in urinary thromboxane excretion as compared with patients who remained asymptomatic. The increased urinary thromboxane excretion and clinical signs could be inhibited by a platelet-specific aspirin regimen of 50 mg/d without affecting vascular cyclooxygenase, indicating that platelets were the main source of the increased thromboxane generation. These data suggest that in symptomatic patients an enhanced formation of thromboxane by platelets, reflecting platelet activation in vivo, precedes the development of arterial microvascular thrombosis. These data provide a rationale for using low-dose aspirin as an antithrombotic agent in thrombocythaemia.

Diagnosis, pathogenesis and treatment of the myeloproliferative disorders essential thrombocythemia, polycythemia vera and essential megakaryocytic granulocytic metaplasia and myelofibrosis

According to strict clinical, hematological and morphological criteria, the Philadelphia (Ph) chromosome negative chronic myeloproliferative disorders essential thrombocythemia (ET), polycythemia vera (PV), and agnogenic myeloid (megakaryocytic/granulocytic) metaplasia (AMM) or idiopathic myelofibrosis (IMF) are three distinct disease entities with regard to clinical manifestations, natural history and outcome in terms of life expectancy. As clonality studies have clearly demonstrated that fibroblast proliferation in AMM, as well as in many other conditions such as advanced stages of Ph(+)-essential thrombocythemia, Ph(+)-granulocytic leukemia, and Ph(-)-polycythemia vera, is polyclonal indicating that myelofibrosis is secondary to the megakaryocytic granulocytic metaplasia in these various conditions, AMM is illogically labeled as IMF. As abnormal megakaryocytic granulocytic metaplasia is the essential feature preceding the early prefibrotic stage of AMM, the term essential megakaryocytic granulocytic metaplasia (EMGM) can readily be used to characterize this condition more appropriately at the biological level. Clinical, hematological and morphological characteristics, in particular megakaryocytopoiesis and bone marrow cellularity, reveal diagnostic features, which enable a clear-cut distinction between ET, PV and EMGM or classical IMF. The characteristic increase and clustering of enlarged megakaryocytes with mature cytoplasm and multilobulated nuclei and their tendency to cluster in a normal or only slightly increased cellular bone marrow represent the hallmark of ET. The characteristic increase and clustering of enlarged mature and pleiomorphic megakaryocytes with multilobulated nuclei and proliferation of erythropoiesis in a moderate to marked hypercellular bone marrow with hyperplasia of dilated sinuses are the specific diagnostic features of untreated PV. EMGM, including the early prefibrotic stages as well as the various myelofibrotic stages of classical IMF appear to be a distinct neoplastic dual proliferation of abnormal megakaryopoiesis and granulopoiesis. The histopathology of the bone marrow in prefibrotic EMGM and in classical IMF is dominated by atypical, enlarged and immature megakaryocytes with cloud-like immature nuclei, which are not seen in ET and PV at diagnosis and during follow-up. Myelofibrosis in ET, PV and EMGM is graded into: no reticulin fibrosis (MF0), early reticulin fibrosis (MF1), advanced reticulin sclerosis with minor or moderate collagen fibrosis (MF2) and advanced collagen fibrosis with osteosclerosis (MF3). Myelofibrosis is not a feature of ET at diagnosis and during long-term follow-up. Myelofibrosis may be present in a minority of PV-patients at diagnosis and usually becomes apparent during long-term follow-up in the majority of PV-patients. Myelofibrosis secondary to the abnormal megakaryocytic and granulocytic myeloproliferation constitutes a prominent feature in the majority of EMGM/IMF at time of diagnosis and usually progresses more or less rapidly during the natural history of the disease. Life expectancy is normal in ET, normal during the 1st ten years and compromised during the 2nd ten years follow-up in PV, but significantly shortened in the prefibrotic stage of EMGM as well as in the various myelosclerotic stages of classical IMF. First line treatment options in prospective randomized clinical trials of newly diagnosed MPD-patients are control of platelet function with low-dose aspirin versus reduction of platelet count with anagrelide, interferon or hydroxyurea in ET; control of platelet and erythrocyte counts by interferon alone versus bloodletting plus hydroxyurea on indication in PV; interferon versus no treatment in the early stages of EMGM; a wait and see strategy in the fibrotic stages of EMGM or classical IMF with favorable prognostic factors, and bone marrow transplantation in classical IMF with poor prognostic factors at presentation or during short-term follow-up.

Normal life expectancy and thrombosis-free survival in aspirin treated essential thrombocythemia

Focusing on platelet-mediated erythromelalgia as a specific, presenting, and single sign of essential thrombocythemia (ET) we were able to define the characteristic peripheral blood and bone marrow findings in ET patients. From 1974 to 1986 we treated 20 symptomatic ET patients with microvascular circulation disturbances including erythromelalgia (N = 18), atypical or typical transient ischemic attacks (N = 6), or acute coronary ischemic syndrome (N = 3) with aspirin and one course of busulfan. The mean platelet counts before and after busulfan treatment were 1,009 (range 545-1,525) and 241 (range 159-315) x 10(9)/L, respectively. After induction of a complete remission, treatment with busulfan and aspirin was discontinued until symptoms returned. All 20 patients remained asymptomatic as long as ET was in maintained remission (platelet < 350 x 10(9)/L) for 4 to 61 (mean 36) months. Eight patients became symptomatic and 4 patients remained asymptomatic at relapse of ET after a follow-up period of 19 to 61 and 31 to 46 months, respectively. Platelet counts at time of symptomatic relapse in the 8 patients were 410, 450, 490, 500, 515, 545, 548, and 635 x 10(9)/L and at time of asymptomatic relapse in 4 ET patients 577, 600, 648, and 725 x 10(9)/L. Based on these observations, since 1986 we followed the strategy to treat ET patients with aspirin as long as the platelet count was between 400 and 1,000 up to 1,250 x 10(9)/L. Clear indications to reduce the platelet count were bleeding, aspirin side effects, and platelets counts above 1500 x 10(9)/L. This nonleukemogenic or least toxic approach in ET is the rationale behind the normal life expectancy and subsequent thrombosis-free survival in 68 ET patients after a mean follow-up period of 6.2 years.

Phenotype variability of the dominant beta-thalassemia induced in four Dutch families by the rare cd121 (G-->T) mutation

Eight patients who were carriers of beta-thalassemia induced by the cd121 (G-->T) mutation are described in four nonrelated Dutch families. This mutant, which is considered rare and inherited in a dominant manner, is expressed in a different way among each of the four families and even among carriers of the same family. The symptoms vary from an hemolytic anemia of intermediate gravity with hepatosplenomegaly, inclusion bodies and erythroblastosis, to a mild anemia with minor hematological abnormalities. We report the analytical procedures used for the detection of the mutant, the hematological and clinical data of the four families and discuss the variable physiopathology of this molecular defect. We also compare the variation in fetal hemoglobin expression in relation to the haplotypes of the beta-gene cluster and to the different hematological conditions. The presence of this rare mutant in four nonrelated Dutch families could derive from a single mutation or from multiple events. The existence of the four mutations in three different haplotypes suggests the occurrence of at least two independent events. The presence of five abnormal hemoglobins and the beta-thalassemia defect on different haplotypes at cd121 also suggests a relatively increased rate of mutations at this particular site.

The place of D-dimer testing in an integrated approach of patients suspected of pulmonary embolism

When a patient is suspected of having pulmonary embolism (PE), the first procedure performed in most institutions is lung scintigraphy. Here we propose an alternative diagnostic strategy based on the following sequential combination of procedures: clinical assessment, D-dimer measurement, ultrasonography of lower limbs, and lung scan. This integrated approach may rule out PE in the majority of outpatients suspected of PE and permits district hospitals without lung-scan facilities to manage approximately 50% of outpatients without referral. D-dimer alone will exclude PE in about 30% of patients at low cost. This stepwise strategy is especially useful because only 20-35% of patients suspected of PE really have the disease. Thus, in the majority of patients, ruling out the disease has replaced ruling in the disease.