Pediatric splenic infarction: Assessment of associated clinical conditions and outcome.

Pediatric splenic infarction (SI) is rare yet clinically significant. Publications regarding this complication are mostly limited to case reports. This is a retrospective study examining SI etiology, clinical presentation, management, and outcomes among children. Twenty-two patients (median age: 7.9 years) were included, mostly with pre-existing hematological diseases. Splenomegaly (72%), thrombocytopenia, and anemia were common. Most of the patients did not receive antithrombotic therapy yet only two patients experienced recurrences. During follow up 36% of patients died, however no fatalities were attributed to thrombotic or bleeding complications.

Application of a clinical decision rule and laboratory assays in pediatrics: Adult heparin-induced thrombocytopenia.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is rare among pediatric patients. The diagnosis of HIT depends upon clinical decision tools to assess its pretest probability, supported by laboratory evidence of anti-platelet factor 4 (anti-PF4)/heparin antibodies. AIMS: To compare the use of the 4Ts score clinical decision tool, clinical characteristics, and laboratory findings between pediatric and adult patients with suspected HIT. METHODS: We compiled all pediatric patients in our center for whom HIT testing was performed during the years 2015-2021. These were compared with a cohort of consecutive adult patients. Laboratory diagnosis of HIT was performed with particle gel immunoassay (PaGIA) as screening test and confirmed by an automated latex-enhanced immunoturbidimetric assay (LIA) and/or by functional flow cytometry assay (FCA). RESULTS: The cohort included 34 children (under 18 years) and 105 adults. Adults mostly received heparins for thromboembolism prophylaxis and treatment (72.4%, n = 76), and were more frequently treated with low-molecular-weight heparin (LMWH). Children were mostly exposed during cardiopulmonary bypass and extracorporeal membrane oxygenation (ECMO, 61.8%, n = 21), and were more frequently treated with unfractionated heparin (UFH). Compared with adults, children had significantly higher 4Ts scores. Nevertheless, adults had a slightly higher rate of a positive diagnosis of HIT. Six out of 16 adults with confirmed HIT presented with thrombosis (37.5%), whereas all three pediatric patients with HIT presented with thrombosis (p = .087). CONCLUSIONS: 4Ts scores are higher in children compared with adult patients for whom laboratory tests for HIT were obtained. A potentially higher incidence of thrombosis in children with HIT may be attributable to the severity of underlying illness.

The potential role of emicizumab prophylaxis in severe von Willebrand disease.

BACKGROUND: Severe von Willebrand disease (VWD) may be associated with chronic joint damage and may require prophylactic therapy. Emicizumab is a humanized bispecific antibody, which mimics the function of coagulation factor VIII (FVIII), and it has been approved for prophylaxis in hemophilia A. METHODS: This is the first study assessing the potential future role of emicizumab as an alternative prophylactic treatment in patients with severe VWD, based upon a thrombin generation (TG) ex vivo analysis. We report 51 weeks of successful off label emicizumab prophylaxis in a child with severe VWD and recurrent hemarthroses and progressive arthropathy despite adherence to previous prophylaxis with replacement therapy. RESULTS AND CONCLUSIONS: Our work demonstrated that ex vivo spiking with emicizumab increased TG in plasma from patients with type 3 VWD. Similar TG results were observed in our treated patient, whose therapy was well tolerated without any adverse events. Both in vitro and ex vivo TG data support sufficient hemostasis without exceeding the range seen in healthy volunteers. Further collaborative studies on the efficacy and safety of emicizumab prophylaxis in severe VWD is warranted.

Patent Foramen Ovale Closure among Patients with Hypercoagulable States Maintained on Antithrombotic Therapy.

BACKGROUND: Percutaneous device closure was shown to effectively prevent recurrent strokes in patients with patent foramen ovale (PFO). Whether this protective effect is relevant for patients with hypercoagulable states (HCSs) is unknown as they were not represented in prior studies. METHODS: Data on 136 consecutive patients with a PFO and clinically significant HCS were retrospectively collected. PFO closure and antithrombotic regimen were decided on an individual basis by the treating physicians, and adherence to therapy was routinely evaluated. The outcome was the occurrence of cerebrovascular accident (CVA) or transient ischemic attack (TIA). RESULTS: HCS types consisted of antiphospholipid syndrome (31%), factor-5 Leiden mutation (22%), prothrombin mutation (18%), protein S deficiency (15%), protein C deficiency (7%), methyl-tetra-hydro folate reductase mutation (5%), and essential thrombocytosis (2%). 102 patients (75%) were maintained on anticoagulants and the remaining on antiplatelet therapy. PFO closure was undertaken in 85 (63%); antithrombotic therapy was not interrupted prior to or after the procedures. At a mean follow-up of 46 ± 8 months, 23 patients (17%; 95% confidence interval, 9.3-22%) experienced an outcome event, mainly in the form of CVAs (n = 15, 65%). In multivariable analysis, PFO closure was associated with a 5-fold decrease in the risk of CVA/TIA (p = 0.02). This effect was independent of the type of HCS or antithrombotic therapy. CONCLUSIONS: Among patients with HCSs maintained on anticoagulant or antiplatelet therapies, PFO closure was associated with a significantly lower risk of CVA or TIA.

Prognostic value of JAK2V617F mutation in pseudotumor cerebri associated with cerebral venous sinus thrombosis.

OBJECTIVES: To examine the clinical characteristics and prognosis of cerebral venous sinus thrombosis (CVST) that presented as pseudotumor cerebri (PTC) patients with JAK2V617F mutation. METHODS: Medical records of all consecutive patients that presented with PTC and a JAK2V617F mutation who were treated were retrospectively reviewed. Data regarding demographics and ocular presenting symptoms and signs, neurological signs, hematological factors treatment, and prognosis were collected. RESULTS: The most common presenting symptoms were headache (5 patients, 83.3%) and visual obscurations (5 patients, 83.3%). CVST of the sagittal sinus and sigmoid sinus were the most common site of thrombus. Platelet count and hemoglobin count were higher than normal during follow-up. There was significant change in the disk edema degree as well as decline in retinal nerve fiber layer (RNFL) thickness (P < 0.001, P < 0.001, Matched pairs). There was no significant change in visual acuity (VA) or mean deviation (MD) during follow-up (P = 0.95, 0.64, respectively, Matched pairs). CONCLUSIONS: Pseudotumor cerebri resulting from CSVT in our patients with JAK2V617F mutation was frequent in young patients and needed medical and surgical treatment, without improvement in visual functions and in third caused poor visual outcome. Therefore, we believe that a screening test for JAK2V617F mutation should be considered for patients with CVST without known risk factor presenting with PTC, especially when sagittal sinus or sigmoid sinus involvement or thrombocytosis or high hemoglobin are found upon presentation. This might lead to more aggressive management which may improve the visual prognosis of those young patients.

From thrombasthenia to next generation thrombocytopenia: Neonatal alloimmune thrombocytopenia induced by maternal Glanzmann thrombasthenia.

BACKGROUND: Glanzmann thrombasthenia (GT) is a rare autosomal recessive disorder of platelet function caused by mutations in the genes coding for integrin αIIbß3. The aim of this study was to examine the outcome of newborns of GT mothers, with emphasis on thrombocytopenia and bleeding manifestations and their relation to maternal antiplatelet antibodies. PROCEDURE: Medical files of all female patients with GT treated in a single tertiary center from 1999 to 2017 were searched for details on pregnancy and birth. The medical files of their newborns were retrieved, and data on the postnatal course were collected. RESULTS: Nine babies were born to five patients with GT at our center during the study period. Three of the nine newborns had severe thrombocytopenia, and all three were offspring of GT mothers who were positive for antiplatelet antibodies. CONCLUSION: Pregnant GT patients should be examined for platelet antibodies. Assessment and management protocols (including treatment with intravenous immunoglobulins) for fetal and neonatal alloimmune thrombocytopenia should be considered.

Combination of hemostatic therapies for treatment of patients with hemophilia A and inhibitors.

BACKGROUND: Therapy application and monitoring of patients with hemophilia A (HA) and inhibitors are challenging. In the current study, combined FVIII - bypass therapy was implemented for a cohort of severe HA patients with inhibitors. METHODS: Plasma of 15 HA patients with inhibitors was spiked ex vivo with FVIII, rFVIIa, FEIBA and their combinations and thrombin generation (TG) was studied. Some patients who experienced hemarthroses or required minor surgeries were treated by a combined concomitant administration of FVIII+FEIBA as IV bolus doses. RESULTS: TG spiking studies showed individual responses not correlated to inhibitor titer. Combinations of agents augmented TG as compared to any single agent, while combined FVIII+FEIBA yielded the highest TG, supporting it as a potential treatment. Following emergent successful surgery of child treated by concomitant FVIII+FEIBA, a total of 396 episodes in 7/15 patients were treated with concomitant FVIII+FEIBA. Five patients were treated for bleeding episodes only, whereas 2 were children undergoing immune tolerance induction (ITI) with FEIBA prophylaxis. Four minor surgeries were performed on FVIII+FEIBA repeated infusions. Neither thrombosis nor any other adverse events were documented. CONCLUSION: A combination of FVIII+FEIBA may be effective and safe as an alternative treatment option for some high-responding inhibitor patients.

Assessment of Functional Fibrinolysis in Cord Blood Using Modified Thromboelastography.

BACKGROUND: The fibrinolytic system in newborns is immature and probably impaired. The aim of this study was to prospectively evaluate functional fibrinolytic capacity of newborn's cord blood using a new thromboelastometry (rotational thromboelastogram, ROTEM®) test. METHODS: Infants born at Sheba Medical Center were studied prospectively. Cord blood was obtained immediately after clumping, and ROTEM parameters were assessed applying non-activated TEM (NATEM) assay with increasing concentration of tissue plasminogen activator (tPA, 0-200 U/ml). Baseline clotting time (CT), clot formation time (CFT), alpha angle, and maximum clot firmness (MCF) were compared among infants versus adults. Each infant's demographic information was prospectively followed up until discharge. RESULTS: One hundred one newborns were tested. CT and CFT values were lower and alpha angles were higher among neonate's cord blood compared to adults (n = 23; P = 0.001, 0.03, and 0.02, respectively). The addition of tPA significantly shortened CT and CFT, and reduced alpha angles and MCF in both groups. The lysis index at 30 min (LI30) and lysis onset time (LOT) decreased significantly, and fibrinolysis was more rapid in the newborns. Hematocrit and platelet counts in neonates correlated with LI30 (P = 0.035 and 0.037, respectively) and LOT (P = 0.02) when higher tPA concentrations were used. ROTEM values were unrelated to the occurrence of postnatal complications. CONCLUSIONS: This first report of functional fibrinolysis in cord blood demonstrated that neonatal fibrinolysis may be augmented as compared to adult values. Further studies are required to validate this test and assess its predictive value and clinical relevance.

Elevated International Normalized Ratio and Mortality in Hospitalized Patients Treated with Direct Oral Anticoagulants.

BACKGROUND: Direct oral anticoagulants (DOACs) are associated with a prolongation of the prothrombin time and an increased international normalized ratio (INR). The clinical significance of these changes is unclear. This study aimed to examine the association between an elevated INR on admission and in-hospital death and long-term survival in patients treated with DOACs. METHODS: Data were retrospectively retrieved from records of hospitalized patients at the Sheba Medical Center between November 2008 and July 2023. Patients were selected based on DOAC treatment, coagulation profile, and INR test done within 48 hours of hospitalization. The outcomes were in-hospital mortality and mortality in the year following hospitalization. RESULTS: The study included 11,399 hospitalized patients treated with DOACs. Patients with elevated INR had a 180% higher risk of in-hospital mortality (adjusted odds ratio 2.80; 95% confidence interval, 2.30-3.39) and a 57% increased risk of death during the following year (adjusted hazard ratio 1.57; 95% confidence interval, 1.44-1.71). Similar results were observed in subgroup analyses for each DOAC. CONCLUSIONS: An elevated INR on admission is associated with a higher risk for in-hospital death and increased risk for mortality during the first year following hospitalization in hospitalized patients treated with DOACs. This highlights that elevated INR levels in patients on DOACs should not be dismissed as laboratory variations due to DOAC treatment, as they may serve as a prognostic marker.

Management of surgery in persons with hemophilia A receiving emicizumab prophylaxis: data from a national hemophilia treatment center.

Background: Persons with hemophilia A may require surgical procedures. Real-world data on invasive procedures in persons with hemophilia A receiving emicizumab prophylaxis are limited. Objectives: To evaluate the safety of invasive procedures in persons with hemophilia A receiving emicizumab prophylaxis and their outcomes in a longitudinally followed cohort. Methods: Data from medical records of persons with hemophilia A with and without factor VIII (FVIII) inhibitors longitudinally followed at our tertiary center, who received emicizumab prophylaxis and underwent all types of invasive procedures, were retrieved. Outcomes of interest were bleeding and thrombotic complications. Results: Overall, 35 patients underwent 56 invasive procedures, 18 (32.1%) were major. The median age was 36.3 years (IQR, 8.8-55.9 years); 12 patients (34.3%) were younger than 18 years at the time of procedure; 17 (48.6%) were patients with FVIII inhibitors. Among major procedures, orthopedic surgeries prevailed. All patients who underwent major procedures received factor replacement with either recombinant activated factor VII (patients with inhibitors) or FVIII (patients without inhibitors). Factor concentrates were administered prior to 32 (84.2%) of the minor procedures. Repeated doses were given according to international expert opinion recommendations and patients' condition.There were 7 bleeding events in 6 patients, 5 were major bleeds, including 1 patient who underwent a minor procedure without factor replacement. None of the patients experienced a thrombotic complication. Conclusion: Invasive procedures can be performed safely in patients receiving emicizumab prophylaxis with close surveillance after surgery. Factor concentrates may be advised in selected patients undergoing minor procedures.

Chronic thromboembolic pulmonary hypertension in patients with antiphospholipid syndrome: Risk factors and management.

BACKGROUND: Antiphospholipid syndrome (APS) may cause chronic thromboembolic pulmonary hypertension (CTEPH). Current knowledge regarding prevalence and risk factors for CTEPH among APS patients is limited. We sought to determine clinical features and biomarkers that could identify APS subjects suffering from CTEPH, and describe the prevalence, course and treatment outcomes of patients with APS-CTEPH. METHODS: 504 APS patients were treated in our center during 2008 to 2019. We studied clinical and laboratory features of 69 APS patients, comparing 19 patients diagnosed with CTEPH (APS-CTEPH) and treated accordingly, with 50 consecutive age and gender matched patients with no evidence of pulmonary hypertension (APS-No-CTEPH). RESULTS: CTEPH prevalence was 3.8% in our APS cohort and was linked with the following parameters: primary APS (p < 0.05); prior pulmonary embolism (p < 0.001); recurrent venous thromboembolism (VTE) (p < 0.001); lower platelet counts (p < 0.001); triple anti-phospholipid antibodies positivity (p < 0.001), higher titers of anti-cardiolipin IgG (p < 0.001), anti-B2GPI IgG (p < 0.001), and high Russell viper venom time ratio (RVVT-ratio) (p < 0.05). Additionally, history of catastrophic APS was more prevalent in APS-CTEPH vs APS-No-CTEPH (p < 0.05). Of APS-CTEPH patients, 15/19 underwent pulmonary endarterectomy (PEA): In 12/15 the procedure was elective and resulted in good perioperative and long-term outcomes, while only 1 of 3 patients that underwent urgent PEA survived. CONCLUSIONS: CTEPH is relatively common in APS. Primary APS, prior PE, recurrent VTE, thrombocytopenia and specific anti-phospholipid antibodies predict CTEPH in APS. Active assessment for CTEPH in APS patients should be considered, as PEA was found to be effective and relatively safe, especially if electively performed.

Patterns of Recurrent Thrombosis in Primary Antiphospholipid Syndrome-Multicenter, Real-Life Long-Term Follow-Up.

Background: Antiphospholipid syndrome (APS) is an acquired hypercoagulable condition associated with antiphospholipid antibody (aPL) presence. Data on re-thrombosis following APS-diagnosis are limited. Methods: This is a retrospective analysis of new thrombotic events among primary APS (pAPS) patients followed for up to 15 years in three medical centers in Israel. Results: Among 312 primary-APS patients, 143 (46%) had new thrombotic event classified to three patterns: (1) Arterial-associated with heart valve disease (OR 7.24, 95% C.I. 2.26-24.6), hypertension (OR 3, 95% C.I. 1.44-6.25), elevated anti-B2-GPI IgM (OR 1.04, 95% C.I. 0.996-1.08), arterial thrombosis at presentation (OR 1.74 95% C.I. 0.992-3.26), and older age (41 vs. 34 years, p < 0.001). (2) Venous-linked with venous thrombosis at presentation (OR 12.9, 95% C.I. 5.27-31.6, p < 0.001), heart valve disease (OR 9.81 95% C.I. 1.82-52.9, p = 0.018), aGAPSS (OR 1.15 95% C.I. 1.02-1.29), and younger age (31 vs. 36.5 years, p = 0.001); and (3) Combined pattern-associated with heart valve disease (OR 40.5 95% C.I. 7.7-212) and pulmonary embolism (OR 7.47 95% C.I. 1.96-28.5). A 4th variant "the Breakthrough pattern" defined by re-thrombosis despite prophylactic therapy was observed in 100/143 (70%) patients and linked with heart valve disease (OR 8. 95% C.I. 2.43-26.3), venous thrombosis at presentation (OR 2.61 95% C.I. 1.47-4.66), leg ulcers (OR 12.2, 95% C.I. 1.4-107), hypertension (OR 1.99, 95% C.I. 0.92-4.34), and higher aGAPSS (OR 1.08, 95% C.I. 0.99-1.18). Conclusion: In this real-life observation, re-thrombosis was common among pAPS patients including in those recommended to receive prophylactic therapy. Different patterns of recurrence were identified and linked with presenting symptoms, specific serological markers, APS manifestations, and comorbidities. Studies that will address interventions to prevent recurrences of APS-related events are needed.

Long Term Follow up of Patients With Primary Obstetric Antiphospholipid Syndrome.

Introduction: Primary obstetric antiphospholipid syndrome (OAPS) is defined by specific morbidities and/or losses of pregnancy in the presence of persistent antiphospholipid antibodies (aPL). This variant of APS is usually treated during pregnancy and the post-partum period. Data on occurrence of thrombotic event during long term follow-up of OAPS patients is limited. Methods: A multi-centre retrospectively cohort of female patients with primary APS (pAPS) was assembled during 2004-2019. Patients were grouped according to disease presentation as pure OAPS or thrombotic APS (tAPS) for those presenting with thrombosis. Clinical and serological data were compared between groups. Results: Of 219 pAPS female patients 67 (30.6%) were diagnosed with OAPS and 152 (69.4%) with tAPS. During >10 years of follow-up 24/67 (35.8%) OAPS and 71/152 (50%) tAPS suffered a new thrombotic event (p = 0.06), while obstetric morbidity was more likely in the OAPS group (31.3 vs. 10.5%, p < 0.001) respectively. Among patients with OAPS at presentation heart valve disease and the presence of ANA were related to thrombosis following diagnosis (25 vs. 4.7%, p = 0.02; and 45.8 vs. 20.8%, p = 0.04 respectively). Conclusion: Thrombotic event following diagnosis were common among female patients with pAPS regardless of disease presentation. Heart valve disease and ANA positivity may be risk factors for thrombosis during follow-up of patients presenting with pure OAPS.

Long-term outcome after nonsurgical management of Paget-Schroetter syndrome.

OBJECTIVE: Paget-Schroetter syndrome (PSS) is an uncommon disease with potentially debilitating long-term effects. The optimal therapy for PSS is unclear, and the role of surgical decompression of the thoracic outlet is still being questioned. In this study, we present long-term results of patients treated with catheter-directed thrombolysis (CDT) and anticoagulation without surgical management. METHODS: This is a retrospective case series of all patients who previously underwent treatment of PSS in our institution between the years 2007 and 2019. Patients were evaluated for clinical signs of post-thrombotic syndrome (PTS) using a modified Villalta scoring scale, including measurements of the circumference of the treated and untreated arms. Duplex ultrasound examination of the treated vein was performed, and quality of life was evaluated using the shortened Disabilities of the Arm, Shoulder, and Hand questionnaire. RESULTS: Eighteen consecutive patients previously treated for PSS with CDT and anticoagulation compose the cohort of this study. None underwent surgical thoracic outlet decompression. All were contacted and invited for clinical and ultrasound evaluation. Follow-up was available for all patients. Mean age at diagnosis was 29 years (range, 16-46 years), and 15 (79%) were male. Mean time from the index event to the follow-up clinic visit was 109 months (range, 37-176 months). Patients were treated with anticoagulation for a mean period of 26 months (range, 6-120 months). Seventeen patients (94%) had a Villalta score of 0 to 3, consistent with nonexistence of PTS. Fourteen patients (78%) were completely asymptomatic. Seven patients (39%) had no difference in arm circumference. A difference in arm circumference between the treated arm and the healthy arm of 1 cm and 2 cm was seen in nine (50%) and two (11%) patients, respectively. Based on the shortened Disabilities of the Arm, Shoulder, and Hand score, none of the patients suffered from impaired quality of life. Duplex ultrasound scanning of the affected veins was performed on 16 of the 18 patients (89%). The vein appeared patent in all examined patients. In three patients, the wall of the examined vein was thickened and irregular. CONCLUSIONS: This study suggests that PSS patients can be treated with anticoagulation and CDT alone, without the need for surgical thoracic outlet decompression. This is based on long-term follow-up of these patients objectively evaluated by means of valid scoring systems. These findings suggest that symptoms or signs of PTS rarely develop, the patients do not suffer from impaired quality of life, and patency of the diseased vein is commonly maintained.

The Prognostic Role of Neutrophil-to-Lymphocyte Ratio in Patients Hospitalized with Acute Pulmonary Embolism.

Early risk stratification is essential for determining the appropriate therapeutic management approach of pulmonary embolism (PE). This study aimed to evaluate the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) in patients hospitalized with acute pulmonary embolism by investigating its association with mortality in a large-scale population diagnosed and hospitalized with acute PE. We retrieved all consecutive patients hospitalized in an internal medicine department or an intensive care unit in a tertiary medical center from December 2007 to April 2021 with a discharge diagnosis of pulmonary embolism. A total of 2072 patients were included. Patients with above-median NLR (i.e., 5.12) had a higher 30-day mortality risk (adjusted odds ratio (aOR), 2.82; 95% confidence interval (CI) 2.14-3.70) and higher one-year mortality risk (aOR, 2.51; 95% CI 2.04-3.08). Similar trends were demonstrated in a sub-analysis of patients without cancer and hemodynamically stable (i.e., systolic blood pressure over 90 mmHg). Furthermore, the median hospital length of stay in patients with an elevated NLR was higher, and so was the in-hospital mortality rate. Elevated NLR in acute PE is associated with a worse short-term and long-term prognosis and with a longer duration of hospitalization.

Variable responsiveness to clopidogrel and aspirin among patients with acute coronary syndrome as assessed by platelet function tests.

Unresponsiveness to clopidogrel or aspirin has been reported in patients with acute coronary syndrome (ACS). Platelet aggregometry (PA) and the Impact-R [Cone and Plate(let) Analyzer (CPA) technology, measuring whole blood platelet adhesion under flow conditions] were compared in detecting laboratory unresponsiveness to clopidogrel and aspirin among ACS patients. Platelet-rich plasma (PRP) samples were evaluated in 404 patients by PA using adenosine diphosphate (ADP) and arachidonic acid (AA) and whole blood samples by the Impact-R ADP- and AA-response tests. The first cohort (n=114) was assayed by PA on days 1 and 4 of the onset of ACS. A patient with relative decrease of /=70%. A patient with an absolute value of AA-induced maximal aggregation >/=60% was defined as laboratory NR patient to aspirin. The second cohort (n=290) was tested on day 4 by both systems and results analyzed by receiver operating characteristic curve. The following cut-off values of the Impact-R surface coverage were obtained:

ADAMTS-13 regulates platelet adhesion under flow. A new method for differentiation between inherited and acquired thrombotic thrombocytopenic purpura.

ADAMTS-13 cleaves large and ultra-large von Willebrand factor multimers normally secreted by endothelial cells. Severe deficiency of this enzyme leads to thrombotic thrombocytopenic purpura (TTP). We applied the Impact-R system [Cone and plate(let) Analyzer, CPA] to determine optimal conditions for ADAMTS-13 function, to assess it's activity in TTP patients and to distinguish inherited TTP (inTTP) from acquired TTP (acTTP). The role of ADAMTS-13 in platelet adhesion under different conditions was investigated applying recombinant forms of VWF and ADAMTS-13. rVWF was first treated by rADAMTS-13 either in solution or when immobilized on the surface of the well, under static or flow conditions, in the presence or absence of BaCl2. The resulting cleaved VWF fragments were then immobilized and served to assess type 3 von Willebrand disease whole blood platelet adhesion under flow. Maximal effect of the rADAMTS-13 (decrease of platelet adhesion in the absence compared to the presence of BaCl2), was observed when the rVWF was pre-immobilized and the cleavage step took place under flow (85%). Mixing plasma ofTTP patients with normal blood (1:3) yielded a 1.6- to 2-fold increase of platelet adhesion under flow compared to mixing normal plasma with normal blood, at shear rate range of 1,800 - 2,500 s(-1) . Maximal increase of platelet adhesion was observed under 2,050 s(-1) . Under these conditions, the extent of adhesion was similarly higher in patients with inTTP and acTTP versus control [surface coverage (SC) 14.5 +/- 2.8% and 14.6 +/- 2.5% vs.7.4 +/- 1.7%, respectively]. ADAMTS-13 activity measured by collagen-binding test was similarly low (4.2 +/- 3.8% and 3.5 +/- 2.4% vs. 72.2 +/- 8.0%, respectively). An inverse correlation between SC and ADAMTS-13 activity was observed in a patient with inTTP assayed eight times during plasma infusion treatment. Addition of BaCl2 to the mixture of TTP plasma and normal whole blood yielded a decrease in platelet adhesion in inTTP (by 51%) but not in acTTP. The lack of reduction of platelet adhesion in acTTP could presumably be due to the presence of ADAMTS-13 inhibitor in these patients. These results suggest that VWF immobilization and high shear flow yielded optimal conditions for ADAMTS-13 activity, and that introduction of BaCl2 in the Impact-R (CPA) test may be useful for differentiation between inherited and acquired TTP.

Impaired wound healing in factor XIII deficient mice.

Factor XIII that stabilizes fibrin clots in the final stages of blood coagulation also participates in wound healing, as can be inferred from a delay in wound repair in some patients with inherited FXIII deficiency. In this study we evaluated the effect of FXIII on wound healing in FXIII-deficient mice. Three groups of mice (n = 10) were employed: control group, FXIII-deficient group and FXIII-deficient group treated with FXIII concentrate. Excisional wounds were left unsutured and undressed, and mice were followed for eleven days. FXIII-deficient mice exhibited impaired wound healing as has been demonstrated by 15%, 27% and 27% decrease in percentage of wound closure on day 4, 8 and 11, respectively. On day 11 complete healing was observed in control (100% closure), 73.23% in FXIII-deficient and 90.06% in FXIII deficient/FXIII-treated groups (p = 0.007 by ANOVA and p = 0.001 by t-test between control and FXIII-deficient groups). Scoring system representing maturation rate of the wounds showed that the scores for the control, FXIII-deficient and FXIII deficient/FXIII treated groups were 94.9 +/- 4.7, 61.5 +/- 14.5 and 94.5 +/- 6.4, respectively (p < 0.001 by ANOVA). Histological analysis of the lesions performed at day 11 disclosed delayed reepithelization and necrotized fissure in FXIII-deficient mice and normal healing in FXIII-deficient/FXIII-treated mice. The findings of this study confirm that in FXIII-deficient mice wound healing is delayed and the cellular and tissue defects can be corrected by treatment with FXIII, providing evidence for the essential role of FXIII in wound repair and remodeling.

Comparison of oral vs intravenous phytonadione (vitamin K1) in patients with excessive anticoagulation: a prospective randomized controlled study.

BACKGROUND: Treatment of patients with excessive anticoagulation is routinely done by intravenous phytonadione (vitamin K1). Oral administration of phytonadione has been shown to be an effective alternative to the intravenous route, but these methods have never been compared directly. Our objective was to compare efficacy and safety of intravenous vs oral phytonadione treatment in patients with excessive anticoagulation without bleeding. METHODS: The study was a prospective randomized controlled trial of consecutive patients presenting with excessive anticoagulation without major bleeding. Patients with a baseline international normalized ratio (INR) of 6 to 10 (n = 44, 47 episodes) received either intravenous or oral phytonadione (0.5 mg or 2.5 mg, respectively), and patients with an INR greater than 10 (n = 17, 19 episodes) received 1 mg or 5 mg, respectively. Efficacy and safety end points were sequential INR changes and the proportion of patients achieving therapeutic range (INR, 2-4), overcorrection (INR<2.0), or undercorrection (INR>4.0) INR values. RESULTS: Sixty-six episodes of excessive anticoagulation were studied. In patients with baseline INR 6-10 the response to intravenous phytonadione was more rapid than in the oral group, and the proportion of patients reaching therapeutic range INR at 6 hours (11/24 vs 0/23) and at 12 hours (16/24 vs 8/23) was significantly higher. However, mean +/- SD INR values were similar for both groups at 24 hours (2.9 +/- 0.8 vs 2.6 +/- 0.8). Patients in the intravenous group tended to be more often (7/24 vs 2/23) overcorrected (INR<2). In patients with baseline INR values greater than 10 efficacy and safety were comparable for both routes of administration. CONCLUSION: Oral administration of phytonadione had similar efficacy and safety as intravenously administered phytonadione and may be suitable for treatment of patients with excessive anticoagulation.

Impact of pre-treatment INR level on the effect of intravenous low dose vitamin K in patients with excessive anticoagulation.

Administration of vitamin K is the common mode of treatment in excessively anticoagulated patients. However, patient's response to vitamin K varies, depending on the vitamin K dose and the route of administration. Another potential source of variation is the pre-treatment INR which has not been accounted for in most previous studies. In the present study the effect of baseline INR on the response to a single dose of intravenous vitamin K (0.5 mg) was studied in 95 episodes of excessively anticoagulated patients (n = 76). In 67 episodes of moderately excessive baseline INR (6-10) mean INR declined from 8.0 +/- 1.2 to 2.6 +/- 0.9 at 24 hours, 59/67 (88%) responding within the first 12 hours and not requiring a second dose. In contrast, in 28 episodes with highly excessive baseline INR (> 10) response was slower; mean INR declining from 13.6 +/- 2.7 to 4.0 +/- 2.1 at 24 hours. In 14/28 of these episodes, patients failed to respond to vitamin K in the first 12 hours and required a second vitamin K dose. We conclude that INR at presentation affects the response to vitamin K and that this INR value should be considered in determining appropriate vitamin K doses.