Syndromes of thrombosis and hypercoagulability. Congenital and acquired causes of thrombosis

Comparison of Relative Value Units and 30-Day Outcomes Between Primary and Revision Pediatric Spinal Deformity Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of this study was to compare the relative value units (RVUs) and 30-day outcomes between primary and revision pediatric spinal deformity (PSD) surgery.

SUMMARY OF BACKGROUND DATA

PSD surgery is frequently complicated by the need for reoperation. However, there is limited literature on physician reimbursement rates and short-term outcomes following primary versus revision spinal deformity surgery in the pediatric population.

MATERIALS AND METHODS

This study utilizes data obtained from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Pediatric database. Patients between 10 and 18 years of age who underwent posterior spinal deformity surgery between 2012 and 2018 were included. Univariate and multivariate regression were used to assess the independent impact of revision surgery on RVUs and postoperative outcomes, including 30-day readmission, reoperation, morbidity, and complications.

RESULTS

The study cohort included a total of 15,055 patients, with 358 patients who underwent revision surgery. Patients in the revision group were more likely to be younger and male sex. Revision surgery more commonly required osteotomy (13.7% vs. 8.3%, P =0.002).Univariate analysis revealed higher total RVUs (71.09 vs. 60.51, P <0.001), RVUs per minute (0.27 vs. 0.23, P <0.001), readmission rate (6.7% vs. 4.0%, P =0.012), and reoperation rate (7.5% vs. 3.3%, P <0.001) for the revision surgery group. Morbidity rates were found to be statistically similar. In addition, deep surgical site infection, pulmonary embolism, and urinary tract infection were more common in the revision group. After controlling for baseline differences in multivariate regression, the differences in total RVUs, RVUs per minute, reoperation rate, and rate of pulmonary embolism between primary and revision surgery remained statistically significant.

CONCLUSIONS

Revision PSD surgery was found to be assigned appropriately higher mean total RVUs and RVUs per minute corresponding to the higher operative complexity compared with primary surgery. Revision surgery was also associated with poorer 30-day outcomes, including higher frequencies of reoperation and pulmonary embolism.

LEVEL OF EVIDENCE

Level III.

In-Vitro Evaluation of a New Inferior Vena Cava Filter—The Stent-Filter

Inferior vena cava filters are indicated for the prevention of pulmonary embolism when anticoagulation using heparin has failed or is contraindicated. The aim of this study was to assess in an in-vitro setting the efficiency of a new inferior vena cava filter to intercept emboli. The new filter, stent-filter, was inserted into a pulsating flow circuit. Then thrombi were produced by introducing sheep's blood into silicon tubes with 3 mm diameter. A combination of 9% saline solution with 40% glycerol was used as the isosmotic fluid in the circuit. A total of 150 thrombi were introduced into the circuit in 3 stages of 50 events each. The flow rate in each of the 3 stages was altered; initially a rate of 1.0 liter per minute was chosen, and after this, it was increased to 1.5 liters and finally 2.0 liters per minute. The percentage of interceptions was used for statistical analysis. In the in-vitro experiment, the filter captured 94%, 90%, and 92% of the thrombi at flow rates of 1.0, 1.5, and 2.0 liters per second, respectively. In conclusion the new filter was effective in the interception of the thrombi when it was evaluated in in-vitro conditions.

Factor V Leiden Mutation and Other Thrombophilia Markers in Childhood Ischemic Stroke

The aim of this study was to evaluate the association between ischemic childhood stroke and thrombophilia. The prevalence of thrombophilia risk factors in 30 unrelated children with ischemic stroke were compared with 33 age-matched control subjects. Patients and control group were tested for the presence of activated protein C (APC) resistance, antiphospholipid antibodies (APLA), increased factor VIII levels, and for the deficiency of protein C (PC), protein S (PS), and antithrombin. When APCR was detected in patients or in controls, factor V Leiden (FVL) mutation was also tested. Seventeen of 30 patients (56.6%) had at least one thrombophilia marker compared with only 5 of 33 control subjects (15.1%). Three children with ischemic stroke (10%) were affected with a combination of two or more thrombophilia markers whereas none of the children in the control group had a combination of risk factors. Seven of 30 children with ischemic stroke (23.3%) and one of 33 control subjects (3.03%) had APC resistance and in all of them FVL mutation were found. The prevalence of FVL mutation was higher among pediatric stroke patients than among control subjects (p < 0.05). None of the patients but one child from the control group (3.03%) had PS deficiency. Antithrombin and PC deficiencies and the presence of APLA and increased factor VIII levels were more frequent in the pediatric stroke patients than in controls but the difference was not statistically significant (p > 0.05). These data confirm that stroke in children is commonly associated with a combination of multiple risk factors and especially the prevalence of FVL mutation is increased in children with ischemic stroke compared with control subjects.

Therapeutic Update on the Prevention and Treatment of Venous Thromboembolism

Venous thromboembolism (VTE) is a common condition that increases in incidence with age and risk factors. Therapies for VTE are aimed at either preventing the disease in high-risk individuals or treating patients who have developed VTE. Assessing risk and aggressively using the recommended therapies is primacy in preventing VTE in surgical and medical patients. Risk of VTE in medical patients has become more defined in recent years, and prophylaxis in this group can prevent scores of iatrogenic VTE. Treatment of VTE has evolved in the past decade from a condition that required hospitalization for 5 to 7 days to a disease state that can be conveniently and safely treated on an outpatient basis, largely due to the advent of low-molecular-weight heparins and patient self-directed treatment.

Malignant hemispheric cerebral infarction associated with idiopathic systemic capillary leak syndrome

Idiopathic systemic capillary leak syndrome (ISCLS) is a rare condition that is characterized by unexplained episodic capillary hyperpermeability due to a shift of fluid and protein from the intravascular to the interstitial space. This results in diffuse general swelling, fetal hypovolemic shock, hypoalbuminemia, and hemoconcentration. Although ISCLS rarely induces cerebral infarction, we experienced a patient who deteriorated and was comatose as a result of massive cerebral infarction associated with ISCLS. In this case, severe hypotensive shock, general edema, hemiparesis, and aphasia appeared after serious antecedent gastrointestinal symptoms. Progressive life-threatening ischemic cerebral edema required decompressive hemicraniectomy. The patient experienced another episode of severe hypotension and limb edema that resulted in multiple extremity compartment syndrome. Treatment entailed forearm and calf fasciotomies. Cerebral edema in the ischemic brain progresses rapidly in patients suffering from ISCLS. Strict control of fluid volume resuscitation and aggressive diuretic therapy may be needed during the post-leak phase of fluid remobilization.

Pharmacogenetic typing for oral anti-coagulant response among factor V Leiden mutation carriers

CONTEXT

Factor V Leiden mutation is the most common inherited predisposition for hypercoagulability and thereby a common genetic cause for initiation of oral anti-coagulation therapy. There is a dearth of knowledge of coumarin response profile in such thrombophilic population.

AIMS

The current pilot study aims to estimate coumarin sensitivity in an Indian cohort with an inherited thrombophilia risk factor (Factor V Leiden mutation carriers) based on the observed frequency of CYP2C9 (*)2, (*)3 and VKORC1-1639G >A genotype combinations.

SETTINGS AND DESIGN

A retrospective study carried out in a tertiary health care center in India.

MATERIALS AND METHODS

Carriers of FVL mutation were genotyped for CYP2C9 ((*)2, F(*)3) and VKORC1 (-1639G >A) variants by PCR-RFLP technique.

STATISTICAL ANALYSIS USED

Chi-square test to analyze difference in expected and observed genotype frequency.

RESULTS

Sixty-one (n = 61) unrelated carriers of FVL mutation were observed in the 13 years study period. The allele frequency of CYP2C9 (*)2, CYP2C9 (*)3, and VKORC1-1639A in this cohort was 0.06, 0.11, and 0.16, respectively. Six (9.7%) individuals had two of the three variant alleles (heterozygous or homozygous), and 28 (45.9%) were heterozygous for at least one polymorphism.

CONCLUSIONS

Pre-prescription genotyping for coumarin drugs, if introduced in Indians with inherited thrombophilia (in whom oral anti-coagulant therapy may be necessary), is likely to identify 9.7% (hypersensitive) subjects in whom the optimum anti-coagulation may be achieved with reduced dosages, 44.3% (normal sensitivity) who may require higher dose and also 55.6% (hyper and moderate sensitivity) subjects who are likely to experience bleeding episodes.

Antibodies to serine proteases in the antiphospholipid syndrome

It is generally accepted that the major autoantigen for antiphospholipid antibodies (aPL) in the antiphospholipid syndrome (APS) is beta(2)-glycoprotein I (beta(2)GPI). However, a recent study has revealed that some aPL bind to certain conformational epitope(s) on beta(2)GPI shared by the homologous enzymatic domains of several serine proteases involved in hemostasis and fibrinolysis. Importantly, some serine protease-reactive aPL correspondingly hinder anticoagulant regulation and resolution of clots. These results extend several early findings of aPL binding to other coagulation factors and provide a new perspective about some aPL in terms of binding specificities and related functional properties in promoting thrombosis. Moreover, a recent immunological and pathological study of a panel of human IgG monoclonal aPL showed that aPL with strong binding to thrombin promote in vivo venous thrombosis and leukocyte adherence, suggesting that aPL reactivity with thrombin may be a good predictor for pathogenic potentials of aPL.

Postinjury coagulopathy management: goal directed resuscitation via POC thrombelastography

Progressive postinjury coagulopathy remains the fundamental rationale for damage control surgery, but the decision to abort operative intervention must occur before laboratory confirmation of coagulopathy. Current massive transfusion protocols have embraced pre-emptive resuscitation strategies emphasizing administration of packed red blood cells, fresh frozen plasma, and platelets in ratios approximating 1:1:1 during the first 24 hours postinjury, based on US military retrospective experience and recent noncontrolled civilian data. This policy, termed "damage control resuscitation" assumes that patients presenting with life threatening hemorrhage at risk for postinjury coagulopathy should receive component therapy in rations approximating those found in whole blood during the first 24 hours. While we concur with the concept of pre-emptive coagulation factor replacement, and initially suggested this in 1982, we remain concerned for the continued unbridled administration of fresh frozen plasma and platelets without objective evidence of their specific requirement. A major limitation of current massive transfusion protocols is the lack of real time assessment of coagulation function to guide evolving blood component requirements. Existing laboratory coagulation testing was originally designed for evaluation of hemophilia and subsequently used for monitoring anticoagulation therapy. Consequently, the applicability of these tests in the trauma setting has never been proven and the time required to conduct these assays is incompatible with prompt correction of the coagulopathy in the trauma setting. This review examines the current approach to postinjury coagulopathy, including identification of patients at risk, resuscitation strategies, design and implementation of institutional massive transfusion protocols, and the potential benefits of goal-directed therapy by real time assessment of coagulation function via point of care rapid thromboelastography.

Rapid thrombelastography (r-TEG) identifies hypercoagulability and predicts thromboembolic events in surgical patients

BACKGROUND

Despite routine prophylaxis, thromboembolic events (TEs) in surgical patients remain a substantial problem. Furthermore, the timing and incidence of hypercoagulability, which predisposes to these events is unknown, with institutional screening programs serving primarily to establish a diagnosis after an event has occurred. Emerging evidence suggests that point of care (POC) rapid thrombelastography (r-TEG) provides a real-time analysis of comprehensive thrombostatic function, which represents an analysis of both enzymatic and platelet components of thrombus formation. We hypothesized that r-TEG can be used as a screening tool to identify hypercoagulable states in surgical patients and would predict subsequent thromboembolic events.

METHODS

Rapid thrombelastography r-TEG analyses were performed on 152 critically ill patients in the surgical intensive care unit (ICU) during 7 months. Hypercoagulability was defined as clot strength (G)>12.4 dynes/cm(2). Variables of interest for identifying hypercoagulability and thromboembolic events included sex, age, operating hospital service, specific injury patterns, injury severity score (ISS), transfusion within first 24 h, ICU duration of stay, ventilator days, hospital admission days, and thromboprophylaxis. Comparisons between the hypercoagulable and normal groups or between the groups with and without thromboembolic events were performed using Chi-square tests or the Fisher exact test for categorical variables and independent sample t tests or Wilcoxon rank sum tests for continuous variables. Multivariate logistic regression analysis (LR) was performed to identify independent predictors of thromboembolic events. A receiver operating characteristic curve was used to measure the performance of G for predicting the occurrence of a TE event. All tests were 2-sided with significance of P < .05.

RESULTS

In all, 86 patients (67%) were hypercoagulable by r-TEG. More than 85% of patients in the hypercoagulable group and 79% in the normal group received thromboprophylaxis during the study period. The differences between hypercoagulable and normal groups by bivariate analysis included high-risk injuries (52% vs 35%; P = .03), spinal cord injury (27% vs 12%; P = .03), median ICU duration of stay (13 vs 7 days; P < .001), median ventilator days (6 vs 2; P < .001), and median hospital duration of stay (20 vs 13 days; P < .001). A total of 16 patients (19%) of the hypercoagulable group suffered a thromboembolic event, and 10 hypercoagulable patients (12%) had thromboembolic events predicted by prior r-TEG hypercoagulability. No patients with normal coagulability by r-TEG had an event (P < .001). LR analysis showed that the strongest predictor of TE after controlling for the presence of thromboprophylaxis was elevated G value (odds ratio: 1.25, 95% confidence interval [CI]: 1.12-1.39). For every 1 dyne/cm(2) increase in G, the odds of a TE increased by 25%.

CONCLUSION

These results indicate that the presence of hypercoagulability identified by r-TEG is predictive of thromboembolic events in surgical patients. Subsequent study is necessary to define optimal prophylactic treatment strategies for patients with r-TEG proven hypercoagulability.

Pesquisa de marcadores de trombofilia em eventos trombóticos arteriais e venosos: registro de 6 anos de investigação

CONTEXTO: Os autores apresentam uma análise epidemiológica sobre a investigação de marcadores de trombofilia em pacientes que apresentaram eventos trombóticos arteriais e/ou venosos acompanhados no Departamento de Angiologia e de Cirurgia Vascular do CENTERVASC no período de janeiro de 2001 a janeiro de 2007. OBJETIVO: Avaliar a prevalência de marcadores de trombofilias congênitas ou adquiridas nos eventos trombóticos venosos e/ou arteriais. MÉTODOS: Entre janeiro de 2001 e janeiro de 2007, 224 pacientes com eventos trombóticos venosos e/ou arteriais foram submetidos a uma rotina de investigação quanto à presença ou não de marcadores de trombofilia, independentemente da idade e história familiar dos pacientes, topografia do evento e presença ou ausência de fatores trombogênicos extrínsecos. RESULTADOS: Foram detectados marcadores de trombofilia em 112 pacientes (50% dos casos). Nestes, observou-se de modo predominante a positividade para anticorpos antifosfolipídios, anticardiolipina e/ou anticoagulante lúpico (39 casos), bem como a presença do fator V de Leiden (43 casos). O sistema venoso foi significativamente o mais acometido, e a ocorrência associada com condições trombogênicas extrínsecas esteve presente em 56 (50%) dos portadores de marcadores de trombofilias. CONCLUSÕES: A presença de marcadores de trombofilia nos pacientes com eventos trombóticos, venosos e/ou arteriais, independentemente da faixa etária ou da existência de fatores extrínsecos associados, foi significativa.

Novel autoantibodies against the activated coagulation factor IX (FIXa) in the antiphospholipid syndrome that interpose the FIXa regulation by antithrombin

We previously reported that some human antiphospholipid Abs (aPL) in patients with the antiphospholipid syndrome (APS) bind to the homologous enzymatic domains of thrombin and the activated coagulation factor X (FXa). Moreover, some of the reactive Abs are prothrombotic and interfere with inactivation of thrombin and FXa by antithrombin (AT). Considering the enzymatic domain of activated coagulation factor IX (FIXa) is homologous to those of thrombin and FXa, we hypothesized that some aPLs in APS bind to FIXa and hinder AT inactivation of FIXa. To test this hypothesis, we searched for IgG anti-FIXa Abs in APS patients. Once the concerned Abs were found, we studied the effects of the Ab on FIXa inactivation by AT. We found that 10 of 12 patient-derived monoclonal IgG aPLs bound to FIXa and that IgG anti-FIXa Abs in APS patients were significantly higher than those in normal controls (p < 0.0001). Using the mean + 3 SD of 30 normal controls as the cutoff, the IgG anti-FIXa Abs were present in 11 of 38 (28.9%) APS patients. Importantly, 4 of 10 FIXa-reactive monoclonal aPLs (including the B2 mAb generated against beta(2)-glycoprotein I significantly hindered AT inactivation of FIXa. More importantly, IgG from two positive plasma samples were found to interfere with AT inactivation of FIXa. In conclusion, IgG anti-FIXa Ab occurred in approximately 30% of APS patients and could interfere with AT inactivation of FIXa. Because FIXa is an upstream procoagulant factor, impaired AT regulation of FIXa might contribute more toward thrombosis than the dysregulation of the downstream FXa and thrombin.

Venous thromboembolism in elective operations: balancing the choices

BACKGROUND

Venous thromboembolism (VTE) is a recognized cause of morbidity and mortality in hospitalized patients and is reported to account for 250,000 deaths annually. Recent shifts in prophylaxis administration are occurring among surgical specialty groups after observing a lower rate of VTE among patients undergoing elective operation. We report the incidence of VTE from 3 sources to provide an estimate of the true risk of the complication in elective surgery.

METHODS

Data from the Surgical Care Improvement Project (SCIP), University HealthSystem Consortium (UHC), and Kentucky Cabinet for Health and Family Services (CHFS) databases were queried for 2004 for the same operative patient groups.

RESULTS

Of 5,285 operations performed within SCIP 2004, the incidences of deep venous thrombosis (DVT) and pulmonary embolus (PE) were 0.4% and 0.3%, respectively, with no reported deaths. Of 966,474 operations recorded in the UHC 2004 data, rates of DVT and PE were 1.2% and 0.5%, respectively. The incidence rates of DVT and PE among 20,563 patients in the CHFS 2004 database were 0.5% and 0.3%, respectively, and included 3 deaths.

CONCLUSION

VTE and associated mortality rates are extremely low in these 3 large data sources. We believe patients will benefit from an ongoing assessment of real need and complications of carefully risk-adjusted VTE prophylaxis.

Some antiphospholipid antibodies bind to hemostasis and fibrinolysis proteases and promote thrombosis

It is generally accepted that the major autoantigen for antiphospholipid antibodies (aPL) is β2glycoprotein I (β2GPI). Interestingly, some aPL bind to β2GPI and the homologous enzymatic domains of several proteases involved in hemostasis and fibrinolysis, and correspondingly hinder anticoagulant regulation and resolution of clots. These findings are consistent with several early findings of aPL and provide a new perspective about some aPL in terms of their binding specificities and related functional properties in promoting thrombosis. In addition, homologous enzymatic domains of the involved proteases share conformation epitope(s) with β2GPI, thus providing a possible structural basis for some non-mutually exclusive mechanisms of aPL-mediated thrombosis.

Attitudes of Surgical Specialists toward Venous Thromboembolism Prophylaxis in Surgical Patients

Venous thromboembolism (VTE) and pulmonary embolism are serious and potentially life-threatening complications in surgical patients; however, the risk can effectively be lessened using appropriate pharmaceutical and mechanical prophylaxis. Due to the variability in opinions and indications for VTE prophylaxis, proposed guidelines for VTE prophylaxis stratified according to patient- and procedure-oriented risk factors were widely circulated. We investigated to what extent these guidelines were accepted by 147 university and community-based surgeons in mid-America and how the recommendations for prophylaxis compared with recent past surgical practice performed on 5285 patients in Kentucky in 2004. Attitudes varied widely with respect to practice sites, modes, and specialty. Actual practices used in the Surgical Care Improvement Project 2004 varied even more widely and were at substantial variance from recommendations and current Centers for Medicare and Medicaid Services quality measures.

Pulmonary embolism after adult spinal deformity surgery

STUDY DESIGN

Retrospective review.

OBJECTIVE

To determine the incidence and identify the associated risk factors of pulmonary embolism (PE) in patients who receive pharmacologic thromboprophylaxis after adult spinal deformity surgery.

SUMMARY OF BACKGROUND DATA

The risk of PE after adult spinal deformity surgery is reported to be as high as 2.2%. However, the incidence and associated risks of PE in the same patient population who receive postoperative pharmacologic thromboprophylaxis is unknown.

METHODS

The study included 361 adult patients with spinal deformity who underwent 407 corrective spinal procedures for scoliosis, kyphosis, or kyphoscoliosis. The incidence of PE was determined and compared with a study (historical control) of similar patients undergoing similar surgery but without postoperative pharmacologic thromboprophylaxis. Their demographic information, American Society of Anesthesiologists score, operative time, surgical approach, surgical complexity, and intraoperative blood loss were also analyzed to determine the presence of associated risk factors.

RESULTS

Despite universal pharmacologic thromboprophylaxis, 10 pulmonary emboli (2.4%) were diagnosed. Patients undergoing anterior spinal surgery were at a significantly higher risk than those undergoing posterior spinal surgery (P = 0.024). The right-side anterior approach was also associated with a significantly higher incidence of PE compared with the left-sided anterior approach (P = 0.018). Although the rate of PE after posterior spinal surgery did not differ from the historical control, the rate of PE after anterior surgery was reduced by 50% compared with the historical control. Age, gender, estimated blood loss, operative time, revision status, and the number of fusion levels were not significant variables for PE. There were 2 epidural hematomas requiring decompression (0.48%) and 1 wound hematoma (0.24%).

CONCLUSION

Although pharmacologic thromboprophylaxis probably does not have a role after posterior spinal surgery, the data in this study suggest that it does lower the incidence of PE after anterior spinal surgery.

IMAGING DIAGNOSIS?AORTIC THROMBOEMBOLISM ASSOCIATED WITH SPIROCERCOSIS IN A DOG

An 8-year-old neutered female Rhodesian Ridgeback developed acute, nonneurological right pelvic limb lameness. Femoral pulsation was poor, and oscillometric blood pressure measurements between the two pelvic limbs differed markedly. A caudal aortic right external iliac embolus was detected sonographically. Radiographically, there was a caudal esophageal mass and thoracic vertebral spondylitis typical of spirocercosis. Using CT-angiography, a caudal thoracic aortic aneurysm with a mural thrombus was detected. The dog recovered following heparin and aspirin therapy but signs recurred 7 months later. Subsequently, the patient improved on treatment and remains asymptomatic. This report illustrates the value of CT-angiography in detecting aortic thrombosis in dogs with spirocercosis.

Popliteal artery occlusion in a young baseball athlete

Popliteal artery occlusion is a rare vascular complication in athletes and has not been previously documented in baseball players. A 21-year-old male baseball player presented with a 10-month history of progressive claudication because of repeated trauma-induced popliteal artery occlusion from frequently practicing stealing bases by sliding down onto his right leg. He was found to have a transient deficiency in both protein C and protein S. The patient underwent percutaneous transluminal recanalization angioplasty followed by anticoagulation therapy, with good results. This case illustrates the importance of awareness of this potential complication in baseball athletes, work-up for a hypercoagulable state and the feasibility of angioplasty therapy in the management of ischemic limbs after trauma.

Antithrombin Cambridge II (A384S): an underestimated genetic risk factor for venous thrombosis

The antithrombin A384S mutation has a relatively high frequency in the British population but has not been identified in other populations. This variant has been associated with cases of thrombotic disease, but its clinical relevance in venous thrombosis remained unclear. We have conducted a secondary analysis of the prevalence of the mutation in a large case-control study, including 1018 consecutive Spanish patients with venous thromboembolism. In addition, we evaluated its functional consequences in 20 carriers (4 homozygous). This mutation, even in the homozygous state, did not affect anti-Xa activity or antigen levels, and it only slightly impaired anti-IIa activity. Thus, routine clinical methods cannot detect this anomaly, and, accordingly, this alteration could have been underestimated. We identified this mutation in 0.2% of Spanish controls. Among patients, this variant represented the first cause of antithrombin anomalies. Indeed, 1.7% patients carried the A384S mutation, but 0.6% had any other antithrombin deficiency. The mutated allele was associated with an increased risk of venous thrombosis with an adjusted OR of 9.75 (95% CI, 2.2-42.5). This is the first study supporting that antithrombin A384S mutation is a prevalent genetic risk factor for venous thrombosis and is the most frequent cause of antithrombin deficiency in white populations.

Potent and selective TF/FVIIa inhibitors containing a neutral P1 ligand

Inhibition of tissue factor/factor VIIa complex (TF/FVIIa) is an attractive strategy for antithrombotic therapies. We began with an investigation of a non-amidine TF/FVIIa inhibitor based on a modification of amidine compound 1. Optimization of the substituents on the P1 phenyl portion of the compound 1 led to a neutral or less basic alternative for the 4-amidinophenyl moiety. By further optimization of the substituents on the central phenyl ring, a highly potent and selective TF/FVIIa inhibitor 17d was discovered.

Factor V Leiden mutation, deficiency of antithrombin III and elevation of factor VIII in a child with ischemic stroke: a case report

A 4-year-old boy was admitted with left hemiplegia. Thrombophilia marker examination resulted with factor V Leiden mutation heterozygosity, a deficiency of antithrombin III and a high level of factor VIII. Cranial computed tomography scan revealed an ischemic infarct in the region of right anterior cerebral artery. In the literature, combinations of multiple thrombophilia risk factors that trigger cerebral ischemic stroke in children have been emphasized. To our knowledge, this is the first child with these combinations of thrombophilia risk factors and ischemic stroke to be reported in the literature.

Treatment of Acute Pulmonary Embolism: Local Effects of Three Hydrodynamic Thrombectomy Devices in an Ex Vivo Porcine Model

PURPOSE

To report an ex vivo study on the local effects of hydrodynamic thrombectomy for the treatment of acute pulmonary embolism (off-label use).

METHODS

Three devices (6-F AngioJet Xpeedior and 6-F and 8-F Oasis) were used for hydrodynamic thrombectomy inside the arteries of 24 inflated and perfused porcine lung explants. Each system was used at multiple positions inside 4 intact and 4 embolized lungs in vessels measuring 2 to 4 mm, 4 to 6 mm, 6 to 8 mm, and 8 to 10 mm. Angiograms prior to, during, and after catheter positioning and system operation were used to detect arterial wall trauma and to measure local clot removal per 30-second cycle. A total of 21 vessel wall samples were subjected to scanning electron microscopy (SEM) to evaluate non-perforating lesions.

RESULTS

All systems were able to remove clot material. The average recanalized vessel length normalized to 30 seconds for vessel diameters of 2 to 4 and 8 to 10 mm, respectively, was 1.17 and 1.75 cm (AngioJet), 0.97 and 0.25 cm (6-F Oasis), and 2.2 and 1.05 cm (8-F Oasis). Perforations occurred during positioning of the 6-F Oasis (4/78 maneuvers) and 8-F Oasis (13/60), but not the AngioJet (0/89); perforations were also seen during system operation (AngioJet: 21/89 activations, 6-F Oasis: 4/78, and 8-F Oasis: 9/60; all lesions inside vessels <6 mm in diameter). SEM showed 35 lesions, 14 with perforation (contrast extravasation) and 21 without perforation (induced by the tip of the guidewire).

CONCLUSION

The AngioJet was most efficient in clot removal, followed by the 8-F Oasis. The 6-F Oasis was least efficient, but had fewest complications. According to these experiments, the tested hydrodynamic thrombectomy devices may cause perforations in vessels <6 mm in diameter. Changes in catheter design to reduce system-specific complication rates or to improve the efficacy of clot removal are warranted.

Stroke in childhood: experience in Istanbul, Turkey

Our objective was to characterize the etiologic factors and outcome for stroke in children. We retrospectively reviewed the charts of patients between the ages of 40 days and 94 months (36.5 +/- 23.7 months) with stroke seen at Istanbul Medical Faculty, Department of Pediatrics between January 1995 and December 2003. We found 79 cases of stroke: 57 ischemic and 22 hemorrhagic strokes. Seventeen children had vitamin K deficiency dependent hemorrhage. In 14 children stroke occurred as a complication of cardiac disease, 7 had moyamoya disease, 3 had protein C deficiency, 2 had thalassemia, 2 had hyperhomocysteinemia (methylene tetrahydrofolate reductase gene mutation), 2 were heterozygote for factor V Leiden, 3 had Down's syndrome, 1 was diagnosed with antiphospholipid syndrome, 1 had glycogen storage disease, and in 28 children no underlying cause could be found. Multiple risk factors were found in 4 children. The outcome in all 79 stroke patients was as follows: asymptomatic 60%; symptomatic epilepsy or persistent neurologic deficit 37%; death 3%; and recurrent stroke 5%. Thus, an underlying cause for stroke was identified in 65% of the children in the study group; 40% of the children either died or suffered motor and/or cognitive sequelae.

Ischaemic stroke in dogs and humans: a comparative review

Cerebrovascular accidents, also known as strokes, are one of the major causes of disability and mortality among adult humans. The increased availability of magnetic resonance imaging in veterinary medicine means they are being increasingly recognised in dogs, too. Cerebrovascular accident is defined as the sudden onset of non-progressive, focal brain dysfunction as a result of ischaemic infarction or haemorrhage. Focal ischaemic stroke is caused by interruption of the arterial blood flow to a dependent area of brain parenchyma by a thrombus or an embolus. Once the diagnosis of ischaemic stroke is confirmed, potential sources of thrombosis or embolism should be investigated and treated accordingly. Dogs with ischaemic stroke tend to recover within several weeks with supportive care only.

Antithrombotic Therapy for Stroke in Young Adults

Stroke in young adults is a markedly heterogeneous disease, and remains an understudied phenomenon. While advances are being made in our understanding of the pathophysiology of its underlying conditions, treatment concerns are controversial, and clinical trials are sorely lacking. This review presents an overview of some of the relevant management issues in hypercoagulable states, migraine, patent foramen ovale, vascular dissection and venous sinus thrombosis.

Thromboelastography maximum amplitude predicts postoperative thrombotic complications including myocardial infarction

Postoperative thrombotic complications increase hospital length of stay and health care costs. Given the potential for thrombotic complications to result from hypercoagulable states, we sought to determine whether postoperative blood analysis using thromboelastography could predict the occurrence of thrombotic complications, including myocardial infarction (MI). We prospectively enrolled 240 patients undergoing a wide variety of surgical procedures. A cardiac risk score was assigned to each patient using the established revised Goldman risk index. Thromboelastography was performed immediately after surgery and maximum amplitude (MA), representing clot strength, was determined. Postoperative thrombotic complications requiring confirmation by a diagnostic test were assessed by a blinded observer. Ten patients (4.2%) suffered a total of 12 postoperative thrombotic complications. The incidence of thrombotic complications with increased MA (8 of 95 = 8.4%) was significantly (P = 0.0157) more frequent than that of patients with MA < or =68 (2 of 145 = 1.4%). Furthermore, the percentage suffering postoperative MI in the increased MA group (6 of 95 = 6.3%) was significantly larger than that in the MA < or =68 group (0 of 145 = 0%) (P = 0.0035). In a multivariate analysis, increased MA (P = 0.013; odds ratio, 1.16; 95% confidence interval, 1.03-1.20) and Goldman risk score (P = 0.046; odds ratio, 2.39; 95% confidence interval, 1.02-5.61) both independently predicted postoperative MI. A postoperative hypercoagulable state as determined by thromboelastography is associated with postoperative thrombotic complications, including MI, in a diverse group of surgical patients.

Venous thromboembolism prophylaxis in medically ill patients and the development of strategies to improve prophylaxis rates

Venous thromboembolism (VTE) is common but often unrecognized in medically ill patients. Over the past 5 years, three large-scale placebo-controlled trials enrolling a total of 5500 medically ill patients have highlighted the risk of VTE in this group. These trials have helped to define a specific at-risk patient profile, including those admitted to the hospital with severe congestive heart failure, respiratory illness, acute infection, and inflammatory bowel disease. We performed a retrospective review of patients admitted to the medical service at our tertiary care center to define how common the at-risk medical patient is and to evaluate and improve prophylaxis rates in this patient group. The study was conducted in two phases. Based on admission characteristics, patients were stratified into high-risk or low-risk groups for the development of VTE. During the pre-intervention phase, 75% of patients admitted to the medical service were characterized as increased risk for VTE, yet only 43% of these high-risk patients received prophylaxis of any sort. After interventions designed to increase awareness of VTE, we conducted a second review period. In this post-intervention phase, where 79% of patients were at risk for VTE, prophylaxis rates improved to 72%. Based on these results, we conclude that the majority of patients admitted to the medical service at our tertiary care center constitute a high-risk population that warrants consideration for VTE prophylaxis. Implementation of strategies to improve prophylaxis rates, including educational sessions and risk stratification guidelines, can be successful and improve identification and prophylaxis of this population.

Feline arterial thromboembolism: an update

ATE remains a devastating complication of cardiac disease. Despite some improvements in our understanding of the underlying causes and clinical features of this disease, short-term management remains a challenge, and mortality is high. Long-term mortality is primarily attributable to the severe underlying cardiac disease. Many questions remain to be answered regarding the ideal management approach for feline ATE. The authors' preferred diagnostic and therapeutic approaches for these difficult patients are detailed in Box. 1.

Argatroban therapy for antithrombin deficiency and mesenteric thrombosis: case report and review of the literature

Antithrombin deficiency is a hypercoagulable state that can increase the risk for thrombosis, especially in the presence of other procoagulant triggers. Unfractionated heparin and low-molecular-weight heparins may not provide effective anticoagulation since they require antithrombin for activity. Direct thrombin inhibitors, however, work independently of antithrombin. A 21-year-old man with a history of heavy alcohol consumption had thrombosis of the superior mesenteric vein. Infusion with unfractionated heparin was started, and despite repeated boluses and increases to 21 U/kg/hour, the maximum activated partial thromboplastin time reached was 39 seconds. The unfractionated heparin was discontinued, and the direct thrombin inhibitor argatroban was infused at rates of 0.4-0.5 microg/kg/minute. Over the course of several weeks, the patient had numerous operations to remove and repair necrotic bowel. When no further surgery was anticipated, warfarin therapy was started; the argatroban infusion was discontinued when the patient reached the therapeutic target international normalized ratio with warfarin. No recurrent thrombosis or major bleeding occurred. Direct thrombin inhibitors, such as argatroban, seem to be suitable alternatives for acute anticoagulation in patients with antithrombin deficiency.

Suspected pulmonary artery disruption after transvenous pulmonary embolectomy using a hydrodynamic thrombectomy device: clinical case and experimental study on porcine lung explants

PURPOSE

To use porcine lung explants for reconstructing possible situations in which a vessel wall disruption might have occurred in a patient suffering fatal hemoptysis after pulmonary embolectomy with a hydrodynamic thrombectomy device.

METHODS

A 76-year-old woman with massive pulmonary embolism underwent transvenous pulmonary embolectomy using a 6-F AngioJet Xpeedior catheter according to manufacturer's instructions. While activating the device in the middle lobe artery (approximately 8 mm diameter), massive and ultimately fatal arterial bleeding occurred through the tracheal tube. Because no autopsy was authorized, an experimental study was designed to examine possible causes for the vessel disruption. Five fresh porcine heart-lung preparations were examined inside a dedicated chest phantom. Access to the pulmonary vessels was provided through catheters inside the right and left ventricular outlets. A low-flow circulation was maintained with an external pump. The 6-F AngioJet thrombectomy device was activated at 42 sites inside vessels from 2 to 10 mm in diameter; in one lung, 8 activations were made after deliberately withdrawing the guidewire.

RESULTS

Vessels >6 mm in diameter remained intact. Vessel wall disruption occurred in 4 of 7 vessels between 4 and 6 mm in diameter and in 13 of 14 segmental arteries <4 mm in diameter (regardless of whether or not a guidewire was used). The signs of vessel wall disruption included extravasation of contrast material, arteriovenous fistula, and laceration of distal airspaces with contrast inside the bronchus.

CONCLUSIONS

The application of this system has to be considered potentially dangerous when activated inside vessels with diameters <6 mm. The use of this device appears to be safe only inside main branches of the lung vessels at this time. Additional experiments will be required to substantiate these initial results.

Thromboprophylaxis and thrombosis in medical, surgical, trauma, and obstetric/gynecologic patients

The International Consensus and the ACCP Sixth Consensus had a great impact on the clinical acceptance of LMWHs. These recommendations have been instrumental in initiating further clinical trial to answer key questions regarding thromboprophylaxis and in setting a new standard for patient care. Also, the key to cost containment in management of DVT/PE is to (1) define the etiology (blood coagulation protein or platelet defect), institute appropriate long-term therapy as indicated, and assess appropriate family members as indicated if a hereditary defect is found and (2) use LMWH as inpatient management. saving a minimum of 210,000.00 dollars per 1000 patients simply from cost savings of recurrence, saving 17 lives per 1000 patients, and saving exorbitant costs of care for patients with recurrence and development of chronic venous insufficiency. The use of outpatient LMWH will save 4,900,000.00 dollars per 1000 patients if applied to the 70% of patients with DVT who fit the criteria of no comorbid condition requiring hospitalization and who arrive early enough to allow a diagnosis to be sent home or hospitalized for 24 hours or less. The simple defining of defects leading to unexplained thrombosis will add another 3,000,000.00 dollars in savings per 1000 patients with DVT and approximately 350,000.00 dollars per 100 patients with thrombotic stroke. In those with transient ischemic attacks, defining the defect and instituting appropriate antithrombotic therapy, thereby potentially saving approximately 30% from developing a thrombotic stroke, amounts to approximately 350,500.00 dollars (= 30% of 1,168,500.00 dollars) in savings per 100 patients.

Antiphospholipid thrombosis syndromes

Antiphospholipid antibodies are associated strongly with thrombosis and are the most common of the acquired blood protein defects causing thrombosis. Although the precise mechanisms whereby antiphospholipid antibodies alter hemostasis to induce a hypercoagulable state remain unclear, numerous theories, as previously discussed, have been advanced. The most common thrombotic events associated with ACLAs are deep vein thrombosis and pulmonary embolus (type I syndrome), coronary or peripheral artery thrombosis (type II syndrome), or cerebrovascular/retinal vessel thrombosis (type III syndrome), and occasionally patients present with mixtures (type IV syndrome). Patients with type V disease are those with antiphospholipid antibodies and RMS. It is as yet unclear how many seemingly normal individuals who may never develop manifestations of antiphospholipid syndrome (type VI) harbor asymptomatic antiphospholipid antibodies. The relative frequency of ACLAs in association with arterial and venous thrombosis strongly suggests that they should be looked for in any individual with unexplained thrombosis; all three idiotypes (IgG, IgA, and IgM) should be assessed. Also, the type of syndrome (I-VI) should be defined, if possible, because this identification may dictate both the type and the duration of immediate and long-term anticoagulant therapy. Unlike those patients with ACLAs, patients with primary LA-thrombosis syndrome usually have venous thrombosis. Because the aPTT is unreliable in patients with LA (prolonged in only approximately 40%-50% of patients) and usually is not prolonged in patients with ACLAs, definitive tests, including ELISA for ACLA, the dilute Russell's viper venom time for LA, hexagonal phospholipid-neutralization procedure, and B-2-GP-I (IgG, IgA, and IgM) should be ordered immediately when suspecting antiphospholipid syndrome or in individuals with otherwise unexplained thrombotic or thromboembolic events. If these test results are negative, subgroups also should be assessedin the appropriate clinical setting. Most patients with antiphospholipid thrombosis syndrome will fail to respond to warfarin therapy, and except for retinal vascular thrombosis, may fail some types of antiplatelet therapy, so it is of major importance to make this diagnosis so patients can be treated with the most effective therapy for secondary prevention-LMWH or unfractionated heparin in most instances and clopidogrel in some instances.

Anticardiolipin Antibodies and Protein S Deficiency: Two Case Reports

Objective:

To describe episodes of venous thrombosis in two young patients with combined congenital and acquired thrombophilias.

Patients:

Two patients attending a university hospital with episodes of deep vein thrombosis presenting at an unusually young age were studied. Tests for thrombo-philias showed these patients had protein S deficiency combined with high titres of cardiolipin antibodies.

Interventions:

The patients were anticoagulated with oral anticoagulants.

Results:

No further episode of thrombosis was seen in either patient over the following 2 years.

Cnclusions:

A detailed search for inherited and acquired thrombophilias should be undertaken in patients presenting with extensive venous thrombosis at an unusually young age. Oral anticoagulants are effective in managing this clinical problem. Indefinite anticoagulation may be required in patients presenting with combined thrombophilias.