A Comprehensive Literature Review on the Management of Distal Deep Vein Thrombosis

Persistent Peril: Recurrent Deep Vein Thrombosis and Pulmonary Embolism in a Patient With Protein S Deficiency Despite Optimal Anticoagulation Therapies

The clotting system has evolved as an adaptive mechanism to prevent blood loss during vascular damage. However, the intricate nature of the clotting cascade and the complexities of human life can sometimes lead to the unnatural activation of this delicate cascade. This can result in blood clot formation within the cardiovascular system, contributing to a wide range of pathological conditions. Abnormal intravascular coagulation most commonly occurs in the deep veins of the lower extremities, and can emboli to other organs, hence, it is termed "venous thromboembolism" (VTE). In this report, we introduce a challenging case of VTE that poses a dilemma for current medical management. The patient with possible protein S deficiency underwent various guideline-directed medical treatments, yet experienced recurrent VTE episodes, including deep vein thrombosis (DVT) and pulmonary embolism (PE), leading to hospital readmissions. This case report sheds light on our challenges in effectively treating VTE.

COVID-19 vaccine-induced immune thrombotic thrombocytopenia: a review

Rare but serious thrombotic incidents in relation to thrombocytopenia, termed vaccine-induced immune thrombotic thrombocytopenia (VITT), have been observed since the vaccine rollout, particularly among replication-defective adenoviral vector-based severe acute respiratory syndrome coronavirus 2 vaccine recipients. Herein, we comprehensively reviewed and summarized reported studies of VITT following the coronavirus disease 2019 (COVID-19) vaccination to determine its prevalence, clinical characteristics, as well as its management. A literature search up to October 1, 2021 using PubMed and SCOPUS identified a combined total of 720 articles. Following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline, after screening the titles and abstracts based on the eligibility criteria, the remaining 47 full-text articles were assessed for eligibility and 29 studies were included. Findings revealed that VITT cases are strongly related to viral vector-based vaccines, which are the AstraZeneca COVID-19 vaccine (95%) and the Janssen COVID-19 vaccine (4%), with much rarer reports involving messenger RNA-based vaccines such as the Moderna COVID-19 vaccine (0.2%) and the Pfizer COVID-19 vaccine (0.2%). The most severe manifestation of VITT is cerebral venous sinus thrombosis with 317 cases (70.4%) and the earliest primary symptom in the majority of cases is headache. Intravenous immunoglobulin and non-heparin anticoagulant are the main therapeutic options for managing immune responses and thrombosis, respectively. As there is emerging knowledge on and refinement of the published guidelines regarding VITT, this review may assist the medical communities in early VITT recognition, understanding the clinical presentations, diagnostic criteria as well as its management, offering a window of opportunity to VITT patients. Further larger sample size trials could further elucidate the link and safety profile.

Unfractionated heparin versus enoxaparin for venous thromboembolism prophylaxis in intensive care units: a propensity score adjusted analysis

Venous thromboembolism (VTE) is a common complication in hospitalized patients. Pharmacologic prophylaxis is used in order to reduce the risk of VTE events. The main purpose of this study is to compare the prevalence of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients admitted to the intensive care unit (ICU) who received unfractionated heparin (UFH) versus enoxaparin as VTE prophylaxis. Mortality was evaluated as a secondary outcome. This was a Propensity Score Adjusted Analysis. Patients admitted to neurology, surgical, or medical ICUs and screened with venous doppler ultrasonography or computed tomography angiography for detection of VTE were included in the analysis. We identified 2228 patients in the cohort, 1836 (82.4%) patients received UFH and 392 (17.6%) patients received enoxaparin. Propensity score matching yielded a well-balanced cohort of 950 (74% UFH, 26% enoxaparin) patients. After matching, there was no difference in prevalence of DVT (RR 1.05; 95% CI 0.67-1.64, p = 0.85) and PE (RR 0.76; 95% CI, 0.44-1.30, p = 0.31). No significant differences in location and severity of DVT and PE between the two groups were detected. Hospital and intensive care unit stay was similar between the two groups. Unfractionated heparin was associated with a higher rate of mortality, (HR 2.04; 95% CI, 1.13-3.70; p = 0.019). The use of UFH as VTE prophylaxis in ICU patients was associated with a similar prevalence of DVT and PE compared with enoxaparin, and the site and degree of occlusion were similar. However, a higher mortality rate was seen in the UFH group.

Thromboprophylaxis after knee arthroscopy does not decrease the risk of deep vein thrombosis: a network meta-analysis

PURPOSE

The primary aim of this network meta-analysis (NMA) is to compare the incidence of venous thromboembolisms (VTE) and bleeding risk following the use of pharmacological and non-pharmacological thromboprophylaxis for arthroscopic knee surgery (AKS). This study assumed the null hypothesis which was that there will be no difference in the incidence of VTE and bleeding risk when comparing no treatment, pharmacological treatment, and non-pharmacological treatment for preventing VTE events following AKS.

METHODS

A systematic electronic search of CENTRAL, Medline, Embase, and ClinicalTrials.gov was carried out. All English language prospective randomized clinical trials published from date of database inception to November 21, 2021 were eligible for inclusion. All papers addressing arthroscopic knee surgery were eligible for inclusion regardless of timing of surgery, operation, surgical technique, or rehabilitation. Multiple random effects NMAs were conducted to compare all treatments for each outcome. The primary outcome was the incidence of pulmonary embolism (PE) and secondary outcomes consisted of overall deep vein thrombosis (DVT), symptomatic DVT, asymptomatic DVT, and all-cause mortality. Adverse outcomes consisted of major and minor bleeding, as well as adverse events.

RESULTS

A total of nine studies with 4526 patients were included for analysis. There were 1054 patients in the no treatment/placebo group (NT/Placebo), 1646 patients in the graduated compression stockings, 810 patients in the extended-duration (> 10 days) low molecular weight heparin (Ext-LMWH) group, 650 patients in the short-duration (< 10 days) LMWH group (Short-LMWH), and 356 patients in the rivaroxaban group. GCS, Ext-LMWH, Short-LMWH and rivaroxaban all demonstrated low risks of PE, symptomatic DVT, asymptomatic DVT, combined DVT and all-cause mortality. Similarly, all interventions demonstrated a low risk of major bleeding.

CONCLUSION

There is no significant difference in the risk reduction of PEs, symptomatic DVTs, major/minor bleeding, and/or all-cause mortality when using LWMH (including short or extended regimens), rivaroxaban, graduated compression stockings or no treatment following arthroscopic knee surgery. Future primary research on the efficacy of thromboprophylaxis following arthroscopic knee surgery should stratify outcomes based on key patient (i.e., age, sex, comorbidities) and surgical (i.e., major vs. minor surgery) characteristics and should include acetylsalicylic acid as an intervention.

LEVEL OF EVIDENCE

I, network meta-analysis of Level I studies.

Pathogenesis of Two Faces of DVT: New Identity of Venous Thromboembolism as Combined Micro-Macrothrombosis via Unifying Mechanism Based on "Two-Path Unifying Theory" of Hemostasis and "Two-Activation Theory of the Endothelium"

Venous thrombosis includes deep venous thrombosis (DVT), venous thromboembolism (VTE), venous microthrombosis and others. Still, the pathogenesis of each venous thrombosis is not clearly established. Currently, isolated distal DVT and multiple proximal/central DVT are considered to be the same macrothrombotic disease affecting the venous system but with varying degree of clinical expression related to its localization and severity. The genesis of two phenotypes of DVT differing in clinical features and prognostic outcome can be identified by their unique hemostatic mechanisms. Two recently proposed hemostatic theories in vivo have clearly defined the character between "microthrombi" and "macrothrombus" in the vascular system. Phenotypic expression of thrombosis depends upon two major variables: (1) depth of vascular wall damage and (2) extent of the injury affecting the vascular tree system. Vascular wall injury limited to endothelial cells (ECs) in sepsis produces "disseminated" microthrombi, but intravascular injury due to trauma extending from ECs to subendothelial tissue (SET) produces "local" macrothrombus. Pathogen-induced sepsis activates the complement system leading to generalized endotheliopathy, which releases ultra large von Willebrand factor (ULVWF) multimers from ECs and promotes ULVWF path of hemostasis. In the venous system, the activated ULVWF path initiates microthrombogenesis to form platelet-ULVWF complexes, which become "microthrombi strings" that produce venous endotheliopathy-associated vascular microthrombotic disease (vEA-VMTD) and immune thrombocytopenic purpura (ITP)-like syndrome. In the arterial system, endotheliopathy produces arterial EA-VMTD (aEA-VMTD) with "life-threatening" thrombotic thrombocytopenic purpura (TTP)-like syndrome. Typically, vEA-VMTD is "silent" unless complicated by additional local venous vascular injury. A local venous vessel trauma without sepsis produces localized macrothrombosis due to activated ULVWF and tissue factor (TF) paths from damaged ECs and SET, which causes distal DVT with good prognosis. However, if a septic patient with "silent" vEA-VMTD is complicated by additional vascular injury from in-hospital vascular accesses, "venous combined micro-macrothrombosis" may develop as VTE via the unifying mechanism of the "two-path unifying theory" of hemostasis. This paradigm shifting pathogenetic difference between distal DVT and proximal/central DVT calls for a reassessment of current therapeutic approaches.

Prevalence of femoral vein duplication: systematic review and metaanalysis

Background: Duplication of the femoral vein is an important anatomical variation of the venous anatomy which has been shown to have an impact on the diagnosis of deep venous thrombosis by compression ultrasonography. The presence of duplication may result in false negative findings while evaluating for deep venous thrombosis, with serious consequences such as pulmonary embolism and death. This metaanalysis aims to determine the pooled prevalence of duplicated femoral veins. Methods: A systematic search was conducted through the major databases PubMed, Hinari, Embase and Medline to identify studies eligible for inclusion. Appropriate data were extracted and pooled into a random-effects metaanalysis using MetaXL software. The primary and secondary outcomes of the study included the pooled prevalence of duplicated femoral veins and the prevalence of bilaterally duplicated femoral veins, respectively. Results: A total of 11 studies (n = 3,682 limbs) were included. The overall pooled prevalence of duplicated femoral veins was 19.7% (95% CI 11–30). There was a significant difference in prevalence between cadaveric studies (2%, 95% CI 1–4) and imaging studies (25%, 95% CI 17–34). Conclusion: Duplication of the femoral vein is a common variation in the lower limbs. Routine watch-out should be practiced especially when performing lower limb Doppler studies in cases of deep venous thrombosis in order to avoid misdiagnosis and improve diagnostic accuracy.