Prevention and treatment of atherothrombosis: Potential impact of nanotechnology

Complications with atherosclerosis can often lead to fatal clot formation and blood vessel occlusion - also known as atherothrombosis. A key component to the development of atherosclerosis and atherothrombosis is the endothelium and its ability to regulate the balance between prothrombotic and antithrombotic activities. Endothelial surface glycocalyx has a critical role in maintenance of vascular integrity. The endothelial glycocalyx, nitric oxide, prostacyclins, heparan sulfate, thrombomodulin, and tissue factor pathway inhibitor all prevent thrombosis, while P-selectin, among many other factors, favors thrombosis. However, endothelial dysfunction gives rise to the acceleration of thrombotic development and eventually the requirement of antithrombotic therapy. Most FDA-approved anticoagulant and antiplatelet therapies today carry a side effect profile of major bleed. Within the past five years, several preclinical studies using different endothelial targets and nanotechnology as a drug delivery method have emerged to target the endothelium and to enhance current antithrombosis without increasing bleed risk. While clinical studies are required, this review illustrates the proof-of-concept of nanotechnology in promoting a greater safety and efficacy profile through multiple in vitro and in vivo studies.

Post-Discharge Prophylactic Anticoagulation in COVID-19 Patients: A Clinical Dilemma

COVID-19 pandemic has taken a great toll on the health care system worldwide. Along with the pandemic, there is also a concern regarding post COVID-19 complications in recovered patients. Thromboembolism (TE) has been reported as a fatal complication in recovered patients with COVID-19. There is still a great dilemma in post-discharge TE prophylaxis and its long-term benefits. We reported three cases of post COVID-19 with complications related to both diseases as well as post discharge anticoagulant therapy. The first case is about a 60-yr-old male who developed Covid-19 pneumonia (moderate disease) and was discharged on rivaroxaban after initial improvement. 3 weeks later, the patient was readmitted with lower gastro-intestinal bleeding. The other two cases developed pulmonary thromboembolism within a span of 2-3 months (after recovered from Covid-19 pneumonia). Both these patients were not prescribed anticoagulants for TE prophylaxis. There is an imperative need for effective guidelines for post discharge TE prophylaxis in COVID-19.

Common Conditions Requiring Long-Term Anticoagulation in Neurosurgical Patients

Long-term anticoagulant therapy prevents thrombosis. Management of neurosurgical patients with conditions such as atrial fibrillation, mechanical heart valves, and other prothrombotic states necessitates application of a strategy to mitigate hemorrhagic complications of anticoagulation. Development of direct oral anticoagulants, which include the direct thrombin and factor X inhibitors, yields new considerations to be had, in particular, the introduction of reversal agents. This article reviews the more common chronic clinical entities that require the use of prolonged anticoagulant therapy with special consideration for neurosurgical patients. It also includes a discussion of established treatment strategies across available treatment options.

Fetal stroke and cerebrovascular disease: Advances in understanding from lenticulostriate and venous imaging, alloimmune thrombocytopaenia and monochorionic twins

Fetal stroke is an important cause of cerebral palsy but is difficult to diagnose unless imaging is undertaken in pregnancies at risk because of known maternal or fetal disorders. Fetal ultrasound or magnetic resonance imaging may show haemorrhage or ischaemic lesions including multicystic encephalomalacia and focal porencephaly. Serial imaging has shown the development of malformations including schizencephaly and polymicrogyra after ischaemic and haemorrhagic stroke. Recognised causes of haemorrhagic fetal stroke include alloimmune and autoimmune thrombocytopaenia, maternal and fetal clotting disorders and trauma but these are relatively rare. It is likely that a significant proportion of periventricular and intraventricular haemorrhages are of venous origin. Recent evidence highlights the importance of arterial endothelial dysfunction, rather than thrombocytopaenia, in the intraparenchymal haemorrhage of alloimmune thrombocytopaenia. In the context of placental anastomoses, monochorionic diamniotic twins are at risk of twin twin transfusion syndrome (TTTS), or partial forms including Twin Oligohydramnios Polyhydramnios Sequence (TOPS), differences in estimated weight (selective Intrauterine growth Retardation; sIUGR), or in fetal haemoglobin (Twin Anaemia Polycythaemia Sequence; TAPS). There is a very wide range of ischaemic and haemorrhagic injury in a focal as well as a global distribution. Acute twin twin transfusion may account for intraventricular haemorrhage in recipients and periventricular leukomalacia in donors but there are additional risk factors for focal embolism and cerebrovascular disease. The recipient has circulatory overload, with effects on systemic and pulmonary circulations which probably lead to systemic and pulmonary hypertension and even right ventricular outflow tract obstruction as well as the polycythaemia which is a risk factor for thrombosis and vasculopathy. The donor is hypovolaemic and has a reticulocytosis in response to the anaemia while maternal hypertension and diabetes may influence stroke risk. Understanding of the mechanisms, including the role of vasculopathy, in well studied conditions such as alloimmune thrombocytopaenia and monochorionic diamniotic twinning may lead to reduction of the burden of antenatally sustained cerebral palsy.

Testing for thrombophilia in mesenteric venous thrombosis - Retrospective original study and systematic review

The aim was to perform a local study of risk factors and thrombophilia in mesenteric venous thrombosis (MVT), and to review the literature concerning thrombophilia testing in MVT. Patients hospitalized for surgical or medical treatment of MVT at our center 2000-2015. A systematic review of observational studies was performed. In the local study, the most frequently identified risk factor was Factor V Leiden mutation. The systematic review included 14 original studies. The highest pooled percentage of any inherited thrombophilic factor were: Factor V Leiden mutation 9% (CI 2.9-16.1), prothrombin gene mutation 7% (CI 2.7-11.8). The highest pooled percentage of acquired thrombophilic factors were JAK2 V617F mutation 14% (CI -1.9-28.1). The wide range of frequency of inherited and acquired thrombophilic factors in different populations indicates the necessity to relate these factors to background population based data in order to estimate their overrepresentation in MVT. There is a need to develop guidelines for when and how thrombophilia testing should be performed in MVT.

Evaluation of hypercoagulability state in perinatal arterial ischemic stroke with rotation thromboelastometry

BACKGROUND

Perinatal arterial ischemic stroke (PAIS) is an important cause of pediatric morbidity and mortality. The etiology of PAIS remains unknown. Several maternal-neonatal disorders, and especially prothrombotic risk factors, have been reported in infants with perinatal stroke (PS). Rotation thromboelastometry (ROTEM) can analyze the coagulation system, from the beginning of coagulation, through clot formation, and ending with fibrinolysis. The aim of this study was to evaluate the hypercoagulability state in PAIS patients using ROTEM.

METHODS

Patients were obtained by evaluating hospital files retrospectively. Twenty patients with PAIS and 19 healthy controls were included in the study. Prothrombotic risk factors and standard coagulation parameters were collected for all patients. Thromboelastometry (TEM) analysis was performed with the ROTEM® Coagulation Analyzer model Gamma 2500 (Tem International, Munich, Germany). Patients were separated into two groups; Group 1 included PAIS patients with prothrombotic risk factors and Group 2 included patients with no prothrombotic risk factors.

RESULTS

Group 1 includes six patients and Group 2 includes fourteen. Maternal risk factors were reported in 55 % and prothrombotic risk factors were detected in 30 % of the patients. ROTEM analyses were done mean age of 11.2 ± 9.4 months. ROTEM analysis showed that maximum clot firmness (MCF) value on both groups was significantly higher than in the control group, which is consistent with a hypercoagulable state. There was no statistical difference between the MCF values of Group 1 and Group 2. No significant correlations were found between the ROTEM parameters and the hematological parameters.

CONCLUSION

The etiology of PAIS is still unclear. Prothrombotic risk factors may be an important etiology for PAIS. However, standard hematological tests for evaluating prothrombotic risk factors are limited. In our study, ROTEM analyses showed higher maximum clot firmness in PAIS patients compared to controls. ROTEM analyses may suggest a hypercoagulable state due to abnormal fibrinolysis in PAIS patients. Normative data and further research is needed to validate our findings.

Acute subdural hematoma secondary to cerebral venous sinus thrombosis: Case report and review of literature

Cerebral venous sinus thrombosis is a rare type of stroke primarily affecting young women. Diagnosis is generally delayed or overlooked due to a wide spectrum of clinical symptoms. Subdural hematoma secondary to cerebral venous sinus thrombosis is very rare. We report a case of 40-year-old female with cerebral venous sinus thrombosis who presented to us with an acute subdural hematoma and subarachnoid hemorrhage besides venous infarct. Management of such patients is complicated due to the rarity of the condition and contraindication for the use of anticoagulation. We conducted a thorough literature search through PubMed and could find only nine cases of spontaneous subdural hematoma secondary to cerebral venous sinus thrombosis.

Cancer-Associated Stroke: The Bergen NORSTROKE Study

Background

Underlying malignancy can cause ischemic stroke in some patients. Mechanisms include the affection of the coagulation cascade, tumor mucin secretion, infections and nonbacterial endocarditis. The release of necrotizing factor and interleukins may cause inflammation of the endothelial lining, creating a prothrombotic surface that triggers thromboembolic events, including stroke. The aims of this study were to assess the occurrence of cancer in patients who had recently suffered an ischemic stroke and to detect possible associations between stroke and cancer subtypes.

Methods

All ischemic stroke patients registered in the Norwegian Stroke Research Registry (NORSTROKE) as part of the ongoing Bergen NORSTROKE study were included. Blood samples were obtained on admission. Stroke etiology was determined by the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria, and the severity of stroke was defined according to the National Institute of Health Stroke Scale score. Information about cancer disease after stroke was obtained from patient medical records and The Cancer Registry of Norway.

Results

From a total of 1,282 ischemic stroke patients with no history of cancer, 55 (4.3%) patients were diagnosed with cancer after stroke. The median time from stroke onset to cancer diagnosis was 14.0 months (interquartile range 6.2-24.5). Twenty-three (41.8%) patients were diagnosed with cancer within 1 year and 13 (23.6%) within 6 months. The most common cancer type was lung cancer (19.0%). By Cox regression analysis, cancer after stroke was associated with elevated D-dimer levels on admittance (p < 0.001), age (p = 0.01) and smoking (p = 0.04).

Conclusions

Cancer-associated stroke is rare, and routine investigation for cancer seems unwarranted in acute ischemic stroke. However, in stroke patients with elevated levels of blood coagulation factors, C-reactive protein, higher age and a history of smoking, underlying malignancy should be considered. Our study suggests that an unknown stroke etiology does not predict malignancy.

Venous thrombosis and prothrombotic factors in inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) may have an increased risk of venous thrombosis (VTE). PubMed, ISI Web of Knowledge and Scopus were searched to identify studies investigating the risk of VTE and the prevalence of acquired and genetic VTE risk factors and prothrombotic abnormalities in IBD. Overall, IBD patients have a two- to fourfold increased risk of VTE compared with healthy controls, with an overall incidence rate of 1%-8%. The majority of studies did not show significant differences in the risk of VTE between Crohn’s disease and ulcerative colitis. Several acquired factors are responsible for the increased risk of VTE in IBD: inflammatory activity, hospitalisation, surgery, pregnancy, disease phenotype (e.g., fistulising disease, colonic involvement and extensive involvement) and drug therapy (mainly steroids). There is also convincing evidence from basic science and from clinical and epidemiological studies that IBD is associated with several prothrombotic abnormalities, including initiation of the coagulation system, downregulation of natural anticoagulant mechanisms, impairment of fibrinolysis, increased platelet count and reactivity and dysfunction of the endothelium. Classical genetic alterations are not generally found more often in IBD patients than in non-IBD patients, suggesting that genetics does not explain the greater risk of VTE in these patients. IBD VTE may have clinical specificities, namely an earlier first episode of VTE in life, high recurrence rate, decreased efficacy of some drugs in preventing further episodes and poor prognosis. Clinicians should be aware of these risks, and adequate prophylactic actions should be taken in patients who have disease activity, are hospitalised, are submitted to surgery or are undergoing treatment.