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Original Contribution |

Prethrombotic Disorders in Children With Arterial Ischemic Stroke and Sinovenous Thrombosis FREE

Mariana Bonduel, MD; Gabriela Sciuccati, MD; Mirta Hepner, PhD; Aurora Feliú Torres, MD; Graciela Pieroni, PhD; Juan Pablo Frontroth, MLT
[+] Author Affiliations

From the Hematology-Oncology Department, Hospital de Pediatría "Prof. Dr. Juan P. Garrahan," Buenos Aires, Argentina.


Arch Neurol. 1999;56(8):967-971. doi:10.1001/archneur.56.8.967.
Text Size: A A A
Published online

Background  Arterial ischemic stroke (AIS) and sinovenous thrombosis (SVT) are relatively rare events in children. The contribution of prethrombotic disorders to the etiology of these entities has not been completely elucidated.

Objectives  To determine the frequency of inherited and acquired prethrombotic disorders in a pediatric population with AIS and SVT and to report clinical and radiological features.

Methods  From May 1992 to April 1997, 30 consecutive children with AIS and 10 children with SVT were assisted at a single institution. Hemostatic evaluation was performed for all the children. Evaluation included the following assays: protein C, protein S, antithrombin, plasminogen, activated protein C resistance, factor V Leiden mutation, and the detection of antiphospholipid antibodies. Data concerning baseline demographics, risk factors, presenting features, family history of thrombosis, and radiological findings were also recorded.

Results  One or more prethrombotic disorders were present in 9 children (30%) with AIS (inherited protein S deficiency, 2 patients; inherited protein C deficiency, 1 patient; acquired antithrombin deficiency, 2 patients; antiphospholipid antibodies, 3 patients; and antiphospholipid antibodies and plaminogen deficiency, 1 patient) and in 5 children (50%) with SVT (inherited protein S deficiency, 1 patient; acquired antithrombin deficiency, 3 patients; and antiphospholipid antibodies, 1 patient).

Conclusions  Most children studied presented both a variety of risk factors for thrombosis and concomitant prethrombotic disorders. Therefore, a complete hemostatic evaluation for all children with AIS and SVT should be performed, despite the presence of obvious clinical risk factors or lack of family history of thrombosis.

ARTERIAL ISCHEMIC stroke (AIS) and sinovenous thrombosis (SVT) are relatively uncommon events in children,1,2 yet few such epidemiological data have been reported.15 Although the pathogenesis of vascular occlusion is partially understood, inherited and acquired prethrombotic disorders have been identified as a cause of stroke in young people.626

We performed a prospective study, including a complete hemostatic evaluation, to determine the frequency of prethrombotic disorders in a pediatric population with AIS and SVT who were treated at a single center.

From May 1992 to April 1997, a prospective study was performed of 30 consecutive children (13 girls and 17 boys) with AIS and 10 children (3 girls and 7 boys) with SVT, aged 3 months to 18 years, who were treated at the Hospital de Pediatría "Prof. Dr. Juan P. Garrahan", Buenos Aires, Argentina. Cardiological evaluation and echocardiography were performed in all cases. Children with AIS and congenital heart diseases were excluded from further analysis, and newborns were not studied because the authors were not involved in their treatment. Data concerning clinical presentation, underlying diseases and/or circumstantial risk factors, radiological findings, location, and family history of thrombosis were recorded.

Radiological diagnosis of the thrombotic episode and magnetic resonance imaging were made by computed tomography and magnetic resonance angiography, respectively, in all the patients, and by conventional angiography in 15 of 40 patients. Moyamoya syndrome was considered to be present when angiographic findings showed bilateral stenosis of the supraclinoid portion of the internal carotid arteries, profuse collateral network, and progression to complete obstruction of the main arterial channels by sparing of the distal branches.

On admission, laboratory studies included blood cell count; peripheral blood smear; sickle solubility test; serum complement C3 and C4; antinuclear antibodies; rheumatoid factor; and anti-DNA and fasting serum cholesterol, triglycerides, high-density lipoprotein, and low-density lipoprotein levels.

After parental informed consent was obtained, blood samples were collected into 3.2% sodium citrate at a ratio of 9:1 by clean venopuncture. Blood was centrifuged twice at 2500g for 15 minutes. Platelet poor plasma was immediately processed or stored at –70°C. Evaluation for prethrombotic disorders included the following assays in all patients: prothrombin time; activated partial thromboplastin time; thrombin time; reptilase time; fibrinogen; and factors V, VII, and XII activity by standard procedures. Functional activities of protein C, antithrombin, and plasminogen were measured by amidolytic assays (chromogenic substrates; Chromogenix AB, Mölndal, Sweden) and protein C and protein S by clotting assays using a model ST4 coagulometer (Diagnostica Stago, Asnières, France). Immunologic measurements of protein C, protein S (total and free), antithrombin, and plasminogen were made by the Laurell technique27 using polyclonal rabbit antibodies against the respective antigens (protein C, protein S, and antithrombin; Dakopatts, Denmark; Assera plasminogen; Diagnostica Stago). Free protein S was assayed by precipitating bound protein with polyethylene glycol 8000 (3.75%) for 30 minutes at 4°C, followed by electroimmunoassay according to the method by Comp et al.28 Presence of activated protein C resistance (APC-R) was tested using a commercial kit with factor V–deficient plasma as a prediluent for plasma samples (Chromogenix AB). DNA analysis for the factor V Leiden mutation was performed by standard polymerase chain reaction.29

Children having a thrombotic episode before 1994 were called again at a later date for the last 2 tests. The presence of a lupus anticoagulant was determined, based on abnormal screening assay results, mixing studies, and confirmatory assay results, based on the method giving abnormal screening test results.30 Anticardiolipin antibodies IgG and IgM isotypes were performed (Coaliza anticardiolipin IgG and IgM, Chromogenix AB) and calibrated against Harris standards from the University of Louisville, Ky. Serum samples with IgG and IgM values less than 10 µg/mL were defined as negative, 10 to 20 µg/mL as positive at low levels, 20 to 80 µg/mL as positive at moderate levels, and above 80 µg/mL as positive at high levels. Age-appropriate references were used to interpret hemostatic variables.31 Any abnormal result was confirmed with repeat assay 3 to 6 months after the acute thrombosis and 10 days after anticoagulation therapy was ceased.

According to proposed criteria for the antiphospholipid antibody syndrome, only those patients with positive lupus anticoagulant test results and/or positive IgG and/or IgM anticardiolipin antibodies at moderate or high levels in 2 determinations performed more than 8 weeks apart were considered positive for antiphospholipid antibody syndrome.32

Parents were included in the study if any relevant hemostatic abnormality was detected in the child. A positive family history of thrombosis required a first- and/or second-degree relative with thrombosis at a relatively young age.

Table 1 shows baseline demographics, underlying diseases and/or circumstantial risk factors, presenting features, and radiological findings in our cohort. Underlying diseases and/or circumstantial risk factors were detected in 15 children (50%) with AIS and in all children with SVT, 5 of whom had 2 risk factors (Table 1). Seven children had multiple arterial infarcts, and 4 (3 girls and 1 boy) had moyamoya syndrome (1 also had common variable immunodeficiency and 1 presented with Down syndrome). Two of the other 3 patients had acute lymphoblastic leukemia and received Escherichia coli L-asparaginase therapy, and the remaining 1 was a girl with systemic lupus erythematosus (Table 1).

Radiologically, multiple occlusions of the anterior and middle cerebral arteries were detected in the 4 children with moyamoya syndrome and the girl with systemic lupus erythematosus. Multiple occlusions of the middle and posterior cerebral arteries were found in the 2 patients with acute lymphoblastic leukemia and E. coli L-asparaginase therapy (Table 1). Family history of thrombosis was positive for 5 children (Table 1). The laboratory findings of these patients are summarized in Table 2 and Table 3, and their clinical and radiological features are summarized in Table 4.

Table Graphic Jump LocationTable 2. Laboratory Findings for Patients With Arterial Ischemic Stroke*
Table Graphic Jump LocationTable 3. Laboratory Findings for Patients With Sinovenous Thrombosis*
Table Graphic Jump LocationTable 4. Characteristics of Patients With Prethrombotic Disorders*

The incidence of stroke in children is much lower than in adults.1,2 However, the interest in studying this subject in children has increased in recent years.126,33 In our study, some epidemiological data concerning sex predominance, frequency according to age, and frequency of risk factors were similar to other series.14 Prethrombotic disorders may cause or contribute to the pathogenesis of thrombosis.34 Inherited or acquired prethrombotic disorders have been reported in children with AIS or SVT.626 Only one study26 prospectively evaluated a large series of pediatric patients to define the contribution of prethrombotic conditions to cerebral thromboembolism. Therefore, the prevalence of different hemostatic abnormalities in the pediatric population is not well determined.

In our series, 9 (30%) of the 30 children with AIS had prethrombotic disorders. No APC-R or factor V Leiden mutation was found in them. An association between APC-R and factor V Leiden mutation and cerebrovascular disease remains to be determined.3539 Only a few reports have found a relationship in young children between AIS and APC-R and factor V Leiden mutation.2325 We found acquired antithrombin deficiency in children with acute lymphoblastic leukemia or lymphoma who had received E coli L-asparaginase. This drug interferes with protein synthesis, resulting in acquired deficiency of this coagulation protein.40 Plasminogen deficiency is frequently associated with thrombophilia.41 Available studies34 still do not permit definitive statements to be made on the association with a thrombotic risk. In the child of our series with AIS and plasminogen deficiency, the development of thrombosis is thought to be caused by an interaction of this defect with an acquired factor such as antiphospholipid antibodies.34

Compared with previous reports2,4 showing that SVT occurs less often in the absence of predisposing factors, our study showed that all the children had some additional risk factor, and in 5 (50%) of the 10 children, a prethrombotic disorder was detected. The APC-R test and factor V Leiden mutation have been associated with increased risk for venous thrombosis.42 One report43 described these defects as a frequent coagulation abnormality in adults with SVT. Considering the allelic frequency of 1.25% in healthy subjects in Argentina,44 no final conclusion could be obtained in our series because few children were studied.

Lower frequency (13%) of lupus anticoagulant and/or anticardiolipin antibodies was found in our patients with AIS and SVT compared with other pediatric series,13,14,1821 most of which evaluated children with systemic lupus erythematosus.

We did not examine the prothrombin gene that could potentially increase the frequency of abnormalities in young patients with arterial or venous thrombosis.45 Such prethrombotic disorders were regarded as inherited if the family had another member with the same abnormality, whereas a persistent antiphospholipid antibodies positivity pointed to an acquired disorder.

Although no family history of thrombosis was found in 88% of our patients, inherited thrombophilia should not be excluded from consideration because the defect may be caused by a fresh mutation (which is rare) or because affected relatives are still asymptomatic.34

In this prospective study, most children evaluated had underlying risk factors and prethrombotic disorders. Therefore, we recommend performing a hemostatic evaluation of all children with AIS and SVT, despite the presence of obvious clinical risk factors or lack of family history of thrombosis.

Accepted for publication September 12, 1998.

We thank Maureen Andrew, MD, for critical review of the manuscript and Paul Monagle, MD, for helpful comments.

Reprints: Mariana Bonduel, MD, Hospital de Pediatría "Prof. Dr. Juan P. Garrahan," Combate de los Pozos 1881, Buenos Aires, Argentina 1245 (e-mail: garahan@giga.com.ar).

Schoenberg  BSMellinger  JFSchoenberg  DG Cerebrovascular disease in infants and children. Neurology. 1978;28763- 768
Link to Article
de Veber  GAAdams  MAndrew  M Canadian pediatric ischemic stroke registry. Thromb Haemost. 1995;731400
Isler  W Stroke in childhood and adolescence. Eur Neurol. 1984;23421- 424
Link to Article
Barron  TFGusnard  DAZimmerman  RAClancy  RR Cerebral venous thrombosis in neonates and children. Pediatr Neurol. 1992;2112- 117
Link to Article
Brower  MCRollins  NRoach  ES Basal ganglia and thalamic infarction in children. Arch Neurol. 1996;531252- 1256
Link to Article
Israels  SJSeshia  SS Childhood stroke associated with protein C or S deficiency. J Pediatr. 1987;111562- 564
Link to Article
Whitlock  JAJanco  RLPhillips  JA  III Inherited hypercoagulable states in children. Am J Pediatr Hemat Oncol. 1989;11170- 173
Roddy  SMGiang  DW Antiphospholipid antibodies and stroke in an infant. Pediatrics. 1991;87933- 935
Dungan  DDJay  MS Stroke in a early adolescent with systemic lupus erythematosus and coexistent antiphospholipid antibodies. Pediatrics. 1992;9096- 99
Prats  JMGaraizar  CZuazo  ELopez  JPiñán  MAAragües  P Superior sagittal sinus thrombosis in a child with protein S deficiency. Neurology. 1992;422303- 2305
Link to Article
Devilat  MToso  MMorales  M Childhood stroke associated with protein C or S deficiency and primary antiphospholipid syndrome. Pediatr Neurol. 1993;967- 70
Link to Article
Barinagarrementeria  FCantú Brito  CIzaguirre  Rde la Peña  A Progressive intracranial occlusive disease associated with deficiency of protein S: report of two cases. Stroke. 1993;241752- 1756
Link to Article
Göbel  U Inherited or acquired disorders of blood coagulation in children with neurovascular complications. Neuropediatrics. 1994;254- 7
Link to Article
Schöning  MKlein  RKrägeloh-Mann  I  et al.  Antiphospholipid antibodies in cerebrovascular ischemia and stroke in childhood. Neuropediatrics. 1994;258- 14
Link to Article
van Kuijck  MAPRotteveel  JJvan Oostrom  CGNovakova  I Neurological complications in children with protein C deficiency. Neuropediatrics. 1994;2516- 19
Link to Article
Gouault-Heilmann  MQuetin  PDreyfus  M  et al.  Massive thrombosis of venous cerebral sinuses in a 2 year-old boy with a combined inherited deficiency of antithrombin III and protein C [letter]. Thromb Haemost. 1994;72782- 783
Charles  PDFenichel  GM Sneddon and antiphospholipid antibody syndromes causing bilateral thalamic infarction. Pediatr Neurol. 1994;10262- 263
Link to Article
Angelini  LRavelli  ACaporali  RRumi  VNardocci  NMartini  A High prevalence of antiphospholipid antibodies in children with idiopathic cerebral ischemia. Pediatrics. 1994;94500- 503
Uziel  YLaxer  RMBlaser  SAndrew  MScheneider  RSilverman  ED Cerebral vein thrombosis in childhood systemic lupus erythematosus. J Pediatr. 1995;126722- 727
Link to Article
Seaman  DELondino  AVKwoh  CKMedsger  TAManzi  S Antiphospholipid antibodies in pediatric systemic lupus erythematosus. Pediatrics. 1995;961040- 1045
von Scheven  EAthreya  BHRose  CDGoldsmith  DPMorton  L Clinical characteristics of antiphospholipid antibody syndrome in children. J Pediatr. 1996;129339- 345
Link to Article
Kohlhase  BVielhaber  HKehl  HGKececioglu  DKoch  HGNowak-Göttl  U Thromboembolism and resistance to activated protein C in children with underlying cardiac disease. J Pediatr. 1996;129677- 679
Link to Article
Simioni  PDe Ronde  HPrandoni  PSaladini  MBertina  RMGirolami  A Ischemic stroke in young patients with activated protein C resistance: a report of three cases belonging to three different kindred. Stroke. 1995;26885- 890
Link to Article
Nowak-Göttl  UKoch  HGAschka  I  et al.  Resistance to activated protein C (APCR) in children with venous or arterial thromboembolism. Br J Haematol. 1996;92992- 998
Link to Article
Ganesan  VKelsey  HCookson  J  et al.  Activated protein C resistance in childhood stroke [letter]. Lancet. 1996;347260
Link to Article
de Veber  GMacGregor  DCurtis  R  et al.  Prethrombotic disorders in a consecutive cohort of infants and children with cerebral thromboembolism: is testing worthwhile? Thromb Haemost. 1997;(suppl)397
Laurell  CB Electroimmunoassay. Scand J Clin Lab Invest. 1972;2921- 37
Link to Article
Comp  PCNixon  RRCooper  MREsmon  CT Familial protein S deficiency is associated with thrombosis. J Clin Invest. 1984;742082- 2088
Link to Article
Dahlback  B Inherited thrombophilia. Blood. 1995;85607- 614
Brandt  JTTriplett  DAAlvin  BScharrer  I Criteria for the diagnosis of lupus anticoagulants. Thromb Haemost. 1995;741185- 1190
Andrew  MVegh  PJohnston  M  et al.  Maturation of the hemostatic system during childhood. Blood. 1992;801998- 2005
Harris  ENKhamashta  MAHughes  GRV Antiphospholipid antibody syndrome. McCarthy  DJKoopman  WJedsArthritis and Allied Conditions. 12th ed. Philadelphia, Pa Lea & Febiger1991;1201- 1212
Riikonen  RSVahtera  EMKekomäki  RM Physiological anticoagulants and activated protein C resistance in childhood stroke. Acta Paediatr. 1996;85242- 244
Link to Article
Lane  DAMannucci  PMBauer  KA  et al.  Inherited thrombophilia: part 1. Thromb Haemost. 1996;76651- 652
Cushman  MBhushan  FBovill  ETracy  R Plasma resistance to activated protein C in venous and arterial thrombosis. Thromb Haemost. 1994;72647
Ridker  PMHennekens  CHLindpaintner  K  et al.  Mutation in the gene coding for coagulation factor V and the risk of myocardial infarction, stroke and venous thrombosis in apparently healthy men. N Engl J Med. 1995;332912- 917
Link to Article
Kontula  KYlikorkala  AMiettinen  H  et al.  Arg 506 Gln factor V mutation (factor V Leiden) in patients with ischaemic cerebrovascular disease and survivors of myocardial infarction. Thromb Haemost. 1995;73558- 560
van der Bom  JGBots  MLHaverkate  F  et al.  Reduced response to activated protein C is associated with increased risk for cerebrovascular disease. Ann Intern Med. 1996;125265- 269
Link to Article
Emmerich  JAlhenc-Gelas  MAillaud  MF  et al.  Clinical features in 36 patients homozygous for the ARG 506-GLN factor V mutation. Thromb Haemost. 1997;77620- 623
Andrew  MBrooker  LMitchell  L Acquired antithrombin III deficiency secondary to asparaginase therapy in childhood acute lymphoblastic leukemia. Blood Coagul Fibrinolysis. 1994;5(suppl 1)S24- S36
Link to Article
Dolan  GPreston  FE Familial plasminogen deficiency and thromboembolism. Fibrinolysis. 1988;2(suppl 2)26- 34
Link to Article
Zöller  BDahlbäck  B Linkage between inherited resistance to activated protein C and factor V gene mutation in venous thrombosis. Lancet. 1994;3431536- 1538
Link to Article
Martinelli  ILandi  GMerati  G  et al.  Factor V gene mutation is a risk factor for cerebral venous thrombosis. Thromb Haemost. 1996;75393- 394
Hepner  MRoldán  APieroni  G  et al.  Frequency of factor V Arg506 to Gln mutation (FV Leiden) and activated protein C resistance in blood donors in Argentina: a preliminary study. Thromb Haemost. 1997;(suppl)226
Poort  SRRosendaal  FRReitsma  PHBertina  RM A common genetic variation in the 3‘-untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and increase in venous thrombosis. Blood. 1996;883698- 3703

Figures

Tables

Table Graphic Jump LocationTable 2. Laboratory Findings for Patients With Arterial Ischemic Stroke*
Table Graphic Jump LocationTable 3. Laboratory Findings for Patients With Sinovenous Thrombosis*
Table Graphic Jump LocationTable 4. Characteristics of Patients With Prethrombotic Disorders*

References

Schoenberg  BSMellinger  JFSchoenberg  DG Cerebrovascular disease in infants and children. Neurology. 1978;28763- 768
Link to Article
de Veber  GAAdams  MAndrew  M Canadian pediatric ischemic stroke registry. Thromb Haemost. 1995;731400
Isler  W Stroke in childhood and adolescence. Eur Neurol. 1984;23421- 424
Link to Article
Barron  TFGusnard  DAZimmerman  RAClancy  RR Cerebral venous thrombosis in neonates and children. Pediatr Neurol. 1992;2112- 117
Link to Article
Brower  MCRollins  NRoach  ES Basal ganglia and thalamic infarction in children. Arch Neurol. 1996;531252- 1256
Link to Article
Israels  SJSeshia  SS Childhood stroke associated with protein C or S deficiency. J Pediatr. 1987;111562- 564
Link to Article
Whitlock  JAJanco  RLPhillips  JA  III Inherited hypercoagulable states in children. Am J Pediatr Hemat Oncol. 1989;11170- 173
Roddy  SMGiang  DW Antiphospholipid antibodies and stroke in an infant. Pediatrics. 1991;87933- 935
Dungan  DDJay  MS Stroke in a early adolescent with systemic lupus erythematosus and coexistent antiphospholipid antibodies. Pediatrics. 1992;9096- 99
Prats  JMGaraizar  CZuazo  ELopez  JPiñán  MAAragües  P Superior sagittal sinus thrombosis in a child with protein S deficiency. Neurology. 1992;422303- 2305
Link to Article
Devilat  MToso  MMorales  M Childhood stroke associated with protein C or S deficiency and primary antiphospholipid syndrome. Pediatr Neurol. 1993;967- 70
Link to Article
Barinagarrementeria  FCantú Brito  CIzaguirre  Rde la Peña  A Progressive intracranial occlusive disease associated with deficiency of protein S: report of two cases. Stroke. 1993;241752- 1756
Link to Article
Göbel  U Inherited or acquired disorders of blood coagulation in children with neurovascular complications. Neuropediatrics. 1994;254- 7
Link to Article
Schöning  MKlein  RKrägeloh-Mann  I  et al.  Antiphospholipid antibodies in cerebrovascular ischemia and stroke in childhood. Neuropediatrics. 1994;258- 14
Link to Article
van Kuijck  MAPRotteveel  JJvan Oostrom  CGNovakova  I Neurological complications in children with protein C deficiency. Neuropediatrics. 1994;2516- 19
Link to Article
Gouault-Heilmann  MQuetin  PDreyfus  M  et al.  Massive thrombosis of venous cerebral sinuses in a 2 year-old boy with a combined inherited deficiency of antithrombin III and protein C [letter]. Thromb Haemost. 1994;72782- 783
Charles  PDFenichel  GM Sneddon and antiphospholipid antibody syndromes causing bilateral thalamic infarction. Pediatr Neurol. 1994;10262- 263
Link to Article
Angelini  LRavelli  ACaporali  RRumi  VNardocci  NMartini  A High prevalence of antiphospholipid antibodies in children with idiopathic cerebral ischemia. Pediatrics. 1994;94500- 503
Uziel  YLaxer  RMBlaser  SAndrew  MScheneider  RSilverman  ED Cerebral vein thrombosis in childhood systemic lupus erythematosus. J Pediatr. 1995;126722- 727
Link to Article
Seaman  DELondino  AVKwoh  CKMedsger  TAManzi  S Antiphospholipid antibodies in pediatric systemic lupus erythematosus. Pediatrics. 1995;961040- 1045
von Scheven  EAthreya  BHRose  CDGoldsmith  DPMorton  L Clinical characteristics of antiphospholipid antibody syndrome in children. J Pediatr. 1996;129339- 345
Link to Article
Kohlhase  BVielhaber  HKehl  HGKececioglu  DKoch  HGNowak-Göttl  U Thromboembolism and resistance to activated protein C in children with underlying cardiac disease. J Pediatr. 1996;129677- 679
Link to Article
Simioni  PDe Ronde  HPrandoni  PSaladini  MBertina  RMGirolami  A Ischemic stroke in young patients with activated protein C resistance: a report of three cases belonging to three different kindred. Stroke. 1995;26885- 890
Link to Article
Nowak-Göttl  UKoch  HGAschka  I  et al.  Resistance to activated protein C (APCR) in children with venous or arterial thromboembolism. Br J Haematol. 1996;92992- 998
Link to Article
Ganesan  VKelsey  HCookson  J  et al.  Activated protein C resistance in childhood stroke [letter]. Lancet. 1996;347260
Link to Article
de Veber  GMacGregor  DCurtis  R  et al.  Prethrombotic disorders in a consecutive cohort of infants and children with cerebral thromboembolism: is testing worthwhile? Thromb Haemost. 1997;(suppl)397
Laurell  CB Electroimmunoassay. Scand J Clin Lab Invest. 1972;2921- 37
Link to Article
Comp  PCNixon  RRCooper  MREsmon  CT Familial protein S deficiency is associated with thrombosis. J Clin Invest. 1984;742082- 2088
Link to Article
Dahlback  B Inherited thrombophilia. Blood. 1995;85607- 614
Brandt  JTTriplett  DAAlvin  BScharrer  I Criteria for the diagnosis of lupus anticoagulants. Thromb Haemost. 1995;741185- 1190
Andrew  MVegh  PJohnston  M  et al.  Maturation of the hemostatic system during childhood. Blood. 1992;801998- 2005
Harris  ENKhamashta  MAHughes  GRV Antiphospholipid antibody syndrome. McCarthy  DJKoopman  WJedsArthritis and Allied Conditions. 12th ed. Philadelphia, Pa Lea & Febiger1991;1201- 1212
Riikonen  RSVahtera  EMKekomäki  RM Physiological anticoagulants and activated protein C resistance in childhood stroke. Acta Paediatr. 1996;85242- 244
Link to Article
Lane  DAMannucci  PMBauer  KA  et al.  Inherited thrombophilia: part 1. Thromb Haemost. 1996;76651- 652
Cushman  MBhushan  FBovill  ETracy  R Plasma resistance to activated protein C in venous and arterial thrombosis. Thromb Haemost. 1994;72647
Ridker  PMHennekens  CHLindpaintner  K  et al.  Mutation in the gene coding for coagulation factor V and the risk of myocardial infarction, stroke and venous thrombosis in apparently healthy men. N Engl J Med. 1995;332912- 917
Link to Article
Kontula  KYlikorkala  AMiettinen  H  et al.  Arg 506 Gln factor V mutation (factor V Leiden) in patients with ischaemic cerebrovascular disease and survivors of myocardial infarction. Thromb Haemost. 1995;73558- 560
van der Bom  JGBots  MLHaverkate  F  et al.  Reduced response to activated protein C is associated with increased risk for cerebrovascular disease. Ann Intern Med. 1996;125265- 269
Link to Article
Emmerich  JAlhenc-Gelas  MAillaud  MF  et al.  Clinical features in 36 patients homozygous for the ARG 506-GLN factor V mutation. Thromb Haemost. 1997;77620- 623
Andrew  MBrooker  LMitchell  L Acquired antithrombin III deficiency secondary to asparaginase therapy in childhood acute lymphoblastic leukemia. Blood Coagul Fibrinolysis. 1994;5(suppl 1)S24- S36
Link to Article
Dolan  GPreston  FE Familial plasminogen deficiency and thromboembolism. Fibrinolysis. 1988;2(suppl 2)26- 34
Link to Article
Zöller  BDahlbäck  B Linkage between inherited resistance to activated protein C and factor V gene mutation in venous thrombosis. Lancet. 1994;3431536- 1538
Link to Article
Martinelli  ILandi  GMerati  G  et al.  Factor V gene mutation is a risk factor for cerebral venous thrombosis. Thromb Haemost. 1996;75393- 394
Hepner  MRoldán  APieroni  G  et al.  Frequency of factor V Arg506 to Gln mutation (FV Leiden) and activated protein C resistance in blood donors in Argentina: a preliminary study. Thromb Haemost. 1997;(suppl)226
Poort  SRRosendaal  FRReitsma  PHBertina  RM A common genetic variation in the 3‘-untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and increase in venous thrombosis. Blood. 1996;883698- 3703

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The American Medical Association is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. The AMA designates this journal-based CME activity for a maximum of 1 AMA PRA Category 1 CreditTM per course. Physicians should claim only the credit commensurate with the extent of their participation in the activity. Physicians who complete the CME course and score at least 80% correct on the quiz are eligible for AMA PRA Category 1 CreditTM.
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For CME Course: A Proposed Model for Initial Assessment and Management of Acute Heart Failure Syndromes
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