Is Virchow's triad complete?

Update on management of cerebral venous thrombosis

PURPOSE OF REVIEW

This review intends to systematize the diagnostic and treatment approach to cerebral venous thrombosis (CVT), highlighting key studies that have been recently published.

RECENT FINDINGS

In light of the recent pandemic, new risk factors for CVT have emerged. Contrast-enhanced MRI and susceptibility-weighted imaging have been shown to offer increased sensitivity for detecting cortical vein thrombosis.Dabigatran seems to be as effective and well tolerated as warfarin for long-term anticoagulation. Partial venous recanalization often occurs in patients treated with anticoagulation only, as early as 8 days after treatment onset. For patients with CVT and impending brain herniation, two-thirds of those who undergo decompressive craniectomy survive, with one-third being functionally independent 6 months after diagnosis.

SUMMARY

CVT is an unusual type of cerebrovascular disease that mostly affects women of fertile age. Risk factors should be identified and addressed. Diagnosis relies on confirmation of venous sinus and/or vein thrombosis, usually by CT venography or MRI. Anticoagulation is the cornerstone of treatment. Despite the lack of high-quality evidence, endovascular treatment is often considered in severe cases. Special populations require tailored approaches. About 80% achieve mRS 0-1, but residual symptoms often affect quality of life and the ability to return to work.

RhoA/rho kinase pathway activation in age-associated endothelial cell dysfunction and thrombosis

The small GTPase RhoA and the downstream Rho kinase (ROCK) regulate several cell functions and pathological processes in the vascular system that contribute to the age-dependent risk of cardiovascular disease, including endothelial dysfunction, excessive permeability, inflammation, impaired angiogenesis, abnormal vasoconstriction, decreased nitric oxide production and apoptosis. Frailty is a loss of physiological reserve and adaptive capacity with advanced age and is accompanied by a pro-inflammatory and pro-oxidative state that promotes vascular dysfunction and thrombosis. This review summarises the role of the RhoA/Rho kinase signalling pathway in endothelial dysfunction, the acquisition of the pro-thrombotic state and vascular ageing. We also discuss the possible role of RhoA/Rho kinase signalling as a promising therapeutic target for the prevention and treatment of age-related cardiovascular disease.

A snake venom-analog peptide that inhibits SARS-CoV-2 and papain-like protease displays antithrombotic activity in mice arterial thrombosis model, without interfering with bleeding time

BACKGROUND

(p-BthTX-I)₂ K, a dimeric analog peptide derived from the C-terminal region of phospholipase A2-like bothropstoxin-I (p-BthTX-I), is resistant to plasma proteolysis and inhibits severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strains with weak cytotoxic effects. Complications of SARS-CoV-2 infection include vascular problems and increased risk of thrombosis; therefore, studies to identify new drugs for treating SARS-CoV-2 infections that also inhibit thrombosis and minimize the risk of bleeding are required.

OBJECTIVES

To determine whether (p-BthTX-I)₂ K affects the hemostatic system.

METHODS

Platelet aggregation was induced by collagen, arachidonic acid, and adenosine diphosphate (ADP) in the Chronolog Lumi-aggregometer. The coagulation activity was evaluated by determining activated partial thromboplastin clotting time (aPTT) and prothrombin time (PT) with (p-BthTX-I)₂ K (5.0-434.5 µg) or 0.9% NaCl. Arterial thrombosis was induced with a 540 nm laser and 3.5-20 mg kg^- 1 Rose Bengal in the carotid artery of male C57BL/6J mice using (p-BthTX-I)₂ K. Bleeding time was determined in mouse tails immersed in saline at 37 °C after (p-BthTX-I)₂ K (4.0 mg/kg and 8.0 mg/kg) or saline administration.

RESULTS

(p-BthTX-I)₂ K prolonged the aPTT and PT by blocking kallikrein and FXa-like activities. Moreover, (p-BthTX-I)₂ K inhibited ADP-, collagen-, and arachidonic acid-induced platelet aggregation in a dose-dependent manner. Further, low concentrations of (p-BthTX-I)₂ K extended the time to artery occlusion by the formed thrombus. However, (p-BthTX-I)₂ K did not prolong the bleeding time in the mouse model of arterial thrombosis.

CONCLUSION

These results demonstrate the antithrombotic activity of the peptide (p-BthTX-I)₂ K possibly by kallikrein inhibition, suggesting its strong biotechnological potential.

Percutaneous transluminal angioplasty for suspected vertebral artery stump syndrome

Vertebral artery stump syndrome is a rare disease associated with a posterior circulation stroke after vertebral artery origin occlusion. However, few reports have addressed its management. We herein present a case involving a patient with vertebral artery stump syndrome who underwent successful intravascular intervention. We also present a literature review of previous cases of this rare disease. The present case involved a 91-year-old man with acute onset of vertigo and disturbance of consciousness. Diffusion-weighted imaging showed an acute ischaemic stroke in the bilateral cerebellar hemispheres. Magnetic resonance angiography revealed left vertebral artery origin occlusion. Angiography detected a nearly occluded left vertebral artery site, with distal antegrade collateral flow via the deep cervical artery at the C6 level. We observed intravascular stasis at the proximal end of the left vertebral artery via the collateral flow. We performed percutaneous transluminal angioplasty towards the occluded left vertebral artery site. The flow from the left vertebral artery was significantly improved. This is the first report of percutaneous transluminal angioplasty performed for vertebral artery stump syndrome. Although vertebral artery stump syndrome has a high risk of recurrence and a poor prognosis, endovascular intervention showed a better outcome than pharmacotherapy in our patient. However, such cases are rare and further investigations are needed.

Thrombotic Risk in Cancer Patients: Diagnosis and Management of Venous Thromboembolism

Venous thromboembolism (VTE) represents a major health problem, especially in cancer patients, who experience a significantly higher incidence of both deep vein thrombosis and pulmonary embolism compared to the general population. Indeed, patients with cancer have a prothrombotic state resulting in both increased expression of procoagulants and suppression of fibrinolytic activity. In addition, VTE increases the morbidity and mortality of these patients. For all these reasons, the prevention and treatment of VTE in cancer setting represent major challenges in daily practice. In general, low-molecular-weight heparin monotherapy is the standard of care for the management of cancer-associated VTE, as Vitamin K antagonists are less effective in this setting. Direct oral anticoagulants offer a potentially promising treatment option for cancer patients with VTE, since recent studies demonstrated their efficacy and safety also in this peculiar setting.

Circulating and tissue microRNAs as a potential diagnostic biomarker in patients with thrombotic events

Venous and arterial thrombosis are conditions that have a considerable burden if left untreated. The hypoxia-induced by the occluded vessel can disrupt the circulation of any organ, the cornerstone of treating thrombosis is rapid diagnosis and appropriate treatment. Diagnosis of thrombosis may be made by using laboratory tests or imaging techniques in individuals who have clinical manifestations of a thrombotic event. The use of serum micro ribonucleic acids (RNAs) has recently been applied to the diagnosis of thrombosis. These small RNA molecules are emerging as new diagnostic markers but have had very limited applications in vascular disease. Most of the articles provided various microRNAs with different levels of accuracy. However, there remains a lack of an appropriate panel of the most specific microRNA in the literature. The purpose of the present review was to summarize the existing data on the use of microRNAs as a diagnostic biomarker for venous thrombosis.

Incidence and risk of venous thromboembolism in patients following appendectomy: a nationwide cohort study

Surgery may lead to poor blood flow and hypercoagulation. Few studies have investigated the incidence of venous thromboembolism (VTE) in Asian patients following appendectomy. We conducted a nationwide cohort study to investigate the risk of VTE in patients who underwent appendectomy compared with those who did not in Taiwan. We studied the entire hospitalized population in Taiwan from 2000 to 2012, with a follow-up period extending to the end of 2013. We identified patients who underwent appendectomy in Taiwan's National Health Insurance Research Database as the appendectomy cohort, and selected a nonappendectomy cohort from the general population that was 4:1 frequency-matched by age (5-year interval), sex, and index year for each appendectomy case. We used Cox models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for symptomatic VTE in the appendectomy cohort for comparison with the nonappendectomy cohort. The appendectomy cohort exhibited a higher incidence of symptomatic VTE than the nonappendectomy cohort (5.90 vs. 3.29 per 10,000 person-years). After adjustment for covariates, a 1.68-fold HR for symptomatic VTE was observed in the appendectomy cohort (95% CI 1.56-1.81). Compared with the nonappendectomy cohort, the patients who underwent open appendectomy had a 1.73-fold increased adjusted HR for symptomatic VTE (95% CI 1.61-1.87). Laparoscopic appendectomy was not significantly associated with symptomatic VTE. An 8.15-fold higher adjusted HR for VTE was observed in patients who underwent appendectomy within the first month after surgery compared with the nonappendectomy cohort. Open appendectomy carried an increased risk of symptomatic VTE. Laparoscopic appendectomy was not significantly associated with symptomatic VTE.

Upper Extremity Deep Venous Thrombosis Prophylaxis After Elective Upper Extremity Surgery

Historically, upper extremity deep venous thromboses (DVTs) have been rare; however, their incidence has increased as awareness has increased. Patients who develop upper extremity DVTs often have multiple comorbidities. However, in the past decade, studies have found a small risk of upper extremity DVTs associated with orthopedic procedures involving the upper extremity. The risk of complications following a DVT, including postthrombotic syndrome and pulmonary embolism, is substantially higher with a DVT of the upper extremity compared with a DVT of the lower extremity. Furthermore, there is no consensus regarding the role and efficacy of prophylactic measures in preventing upper extremity DVT after upper extremity surgery. This article discusses the use of prophylactic agents after elective upper extremity surgery, with an emphasis on the efficacy of commonly used interventions. [Orthopedics. 2018; 41(1):21-27.].

Genetic Analysis of Venous Thromboembolism in UK Biobank Identifies the ZFPM2 Locus and Implicates Obesity as a Causal Risk Factor

BACKGROUND

UK Biobank is the world's largest repository for phenotypic and genotypic information for individuals of European ancestry. Here, we leverage UK Biobank to understand the inherited basis for venous thromboembolism (VTE), a leading cause of cardiovascular mortality.

METHODS AND RESULTS

We identified 3290 VTE cases and 116 868 controls through billing code-based phenotyping. We performed a genome-wide association study for VTE with ≈9 000 000 imputed single-nucleotide polymorphisms. We performed a phenome-wide association study for a genetic risk score of 10 VTE-associated variants. To assess whether obesity is a causal factor for VTE, we performed Mendelian randomization analysis using a genetic risk score instrument composed of 68 body mass index-associated variants. The genome-wide association study for VTE replicated previous findings at the F5, F2, ABO, F11, and FGG loci. We identified 1 new locus-ZFPM2 rs4602861-at genome-wide significance (odds ratio, 1.11; 95% confidence interval, 1.07-1.15; P=4.9×10^-10) and a new independent variant at the F2 locus (rs3136516; odds ratio, 1.10; 95% confidence interval, 1.06-1.13; P=7.60×10^-9). In a phenome-wide association study, a 10 single-nucleotide polymorphism VTE genetic risk score was associated with coronary artery disease (odds ratio, 1.08; 95% confidence interval, 1.05-1.10 per unit increase in VTE odds; P=1.08×10^-9). In a Mendelian randomization analysis, genetically elevated body mass index (a 1 SD increase) was associated with 57% higher risk of VTE (odds ratio, 1.57; 95% confidence interval, 1.08-1.97; P=0.003).

CONCLUSIONS

For common diseases such as VTE, biobanks provide potential to perform genetic discovery, explore the phenotypic consequences for disease-associated variants, and test causal inference.

Cancer-associated venous thromboembolism: Burden, mechanisms, and management

Venous thromboembolism (VTE) is a significant health problem in the general population but especially in cancer patients. In this review, we discuss the epidemiology and burden of the disease, the pathophysiology of cancer-associated VTE, and the clinical treatment options for both primary prevention and acute treatment. Overall, the development of VTE in cancer patients is related to increases in morbidity, mortality, and medical costs. However, the incidence of cancer-associated VTE varies due to patient-related factors (e.g. thrombophilia, comorbidities, performance status, history of venous diseases), tumour-related factors (e.g. cancer site, stage, grade), and treatment-related factors (e.g. surgery, chemotherapy, anti-angiogenesis treatment, hormonal and supportive treatment). Furthermore, blood count parameters (e.g. platelets and leukocytes) and biomarkers (e.g. soluble P-selectin and D-dimer) are predictive markers for the risk of VTE in cancer patients and have been used to enhance risk stratification. Evidence suggests that cancer itself is associated with a state of hypercoagulability, driven in part by the release of procoagulant factors, such as tissue factor, from malignant tissue as well as by inflammation-driven activation of endothelial cells, platelets, and leukocytes. In general, low-molecular-weight heparin (LWMH) monotherapy is the standard of care for the management of cancer-associated VTE, as vitamin K antagonists are less effective in cancer patients. Direct oral anticoagulants (DOACs) offer a potentially promising treatment option for cancer patients with VTE, but recommendations concerning the routine use of DOACs should await head-to-head studies with LMWH.

Common Carotid Artery Stump Syndrome Due to Mobile Thrombus Detected by Carotid Duplex Ultrasonography

Carotid stump syndrome is a cause of recurrent embolic stroke following occlusion of the ipsilateral internal carotid artery. The present report describes a case of recurrent cerebral embolism ipsilateral to a chronically occluded left common carotid artery (CCA), i.e., "CCA stump syndrome." Doppler color flow imaging showed anterograde flow in the left internal and external carotid arteries, which were supplied by collateral flow from the superior thyroid artery inflowing just proximal to the left carotid bifurcation. According to carotid duplex ultrasonography (CDU), a low-echoic mobile thrombus was noted at the distal stump of the occluded CCA, which presumably caused distal embolism. The low-echoic mobile thrombus dramatically changed to a homogenously high-echoic thrombus, and there was no recurrence of stroke after antiplatelet and anticoagulant therapy. This is the first report to demonstrate a CDU-verified temporal change in the thrombus at the stump in CCA stump syndrome. CDU is a noninvasive and useful technique to characterize hemodynamics, thrombus morphology, and the response to therapy.

Progestin isoforms provide different levels of protein S expression in HepG2 cells

INTRODUCTION

Use of combined oral contraceptives (COCs) results in acquired protein S (PS) deficiency, a well-established risk factor for venous thromboembolism (VTE). The risk of VTE due to COCs containing newer-generation progestins is double compared with COCs containing older-generation progestins, although there is little difference in estrogen contents between the generations. In contrast, progestin-only contraceptives do not confer an increased risk of VTE. In this study, we aimed to investigate how different isoforms of progestin in COCs affect the risk of VTE by measuring PS expression.

MATERIALS AND METHODS

The effect of progestin, levonorgestrel (LNG) or drospirenone (DRSP), on PS mRNA expression in HepG2 cells was measured using reverse transcription-quantitative PCR; PS level was determined using Western blot analysis. PROS1 promoter activity, PS mRNA stability, and de novo synthesis of PS mRNA were examined in HepG2 cells after treatment with progestin.

RESULTS AND CONCLUSIONS

In the presence of progestins, PS mRNA and protein expressions were significantly upregulated in HepG2 cells due to the augmentation of de novo PS mRNA expression modulated by RNA polymerase II (Pol II), thereby facilitating PS transcription elongation. Moreover, the transcription elongation inhibitor blocked progestin-mediated de novo PS mRNA expression. Conversely, progestin did not affect PROS1 promoter activity and PS mRNA stability. Pol II elongation efficiency in the newer-generation progestin (DRSP) treatment was not as strong compared with older-generation progestin (LNG), suggesting the difference in VTE risk between COC generations.

Recanalization of symptomatic vertebral ostial occlusion in patients with acute or subacute stroke

SUMMARY

Vertebral artery recanalization in symptomatic stenosis/occlusion remains controversial, as no definite evidence exists regarding this topic. There are only a few reports regarding the feasibility and safety of recanalization in the first segment of the vertebral artery with atherosclerotic vertebral ostial occlusion. We report our experience treating first segment occlusion in 8 patients and present a balloon protection technique used to reduce the thromboembolic burden during the stent placement procedure. The outcome at 3 months showed an mRS ≤2 except for a patient with a poor initial status with basilar artery occlusion. Revascularization of a rather long first segment occlusion is technically feasible and can be safely performed by use of embolic protection methods.

Effects of disturbed flow on vascular endothelium: pathophysiological basis and clinical perspectives

Vascular endothelial cells (ECs) are exposed to hemodynamic forces, which modulate EC functions and vascular biology/pathobiology in health and disease. The flow patterns and hemodynamic forces are not uniform in the vascular system. In straight parts of the arterial tree, blood flow is generally laminar and wall shear stress is high and directed; in branches and curvatures, blood flow is disturbed with nonuniform and irregular distribution of low wall shear stress. Sustained laminar flow with high shear stress upregulates expressions of EC genes and proteins that are protective against atherosclerosis, whereas disturbed flow with associated reciprocating, low shear stress generally upregulates the EC genes and proteins that promote atherogenesis. These findings have led to the concept that the disturbed flow pattern in branch points and curvatures causes the preferential localization of atherosclerotic lesions. Disturbed flow also results in postsurgical neointimal hyperplasia and contributes to pathophysiology of clinical conditions such as in-stent restenosis, vein bypass graft failure, and transplant vasculopathy, as well as aortic valve calcification. In the venous system, disturbed flow resulting from reflux, outflow obstruction, and/or stasis leads to venous inflammation and thrombosis, and hence the development of chronic venous diseases. Understanding of the effects of disturbed flow on ECs can provide mechanistic insights into the role of complex flow patterns in pathogenesis of vascular diseases and can help to elucidate the phenotypic and functional differences between quiescent (nonatherogenic/nonthrombogenic) and activated (atherogenic/thrombogenic) ECs. This review summarizes the current knowledge on the role of disturbed flow in EC physiology and pathophysiology, as well as its clinical implications. Such information can contribute to our understanding of the etiology of lesion development in vascular niches with disturbed flow and help to generate new approaches for therapeutic interventions.

Anticoagulation therapy for vertebral artery stump syndrome

There are very few reports describing the presence of a stump embolism after vertebral artery occlusion. We describe three patients who presented with posterior circulation ischemic strokes after vertebral artery occlusion. These patients were successfully treated with anticoagulation therapy without surgical or endovascular treatment.

[Perioperative thromboprophylaxis in adults]

According to the concept of Virchow, alterations of the blood flow, vascular injury and hypercoagulability of the blood (due to inherited or acquired thrombophilia or as a consequence of perioperative coagulation activation) are causally related to the risk of venous thrombosis. The overall risk of venous thromboembolic events in the perioperative setting ranges between <10% and >50%. The risk is highest in patients undergoing major orthopaedic surgery or cancer surgery. The aim of perioperative thrombosis prophylaxis is to reduce perioperative morbidity and mortality. The article discusses patient- and intervention-dependent thromboprophylactic measures. Recent recommendations for non-pharmacological and pharmacological prophylaxis are presented including the information on the beginning and duration of anticoagulation. Management strategies for patients undergoing abdominal and orthopaedic surgery as well as special aspects of the neurosurgical population and of cancer surgery are highlighted.