ARTICLE | doi:10.20944/preprints202203.0193.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: gas embolism; microfluidics; microvasculature; flow pattern
Online: 15 March 2022 (03:13:48 CET)
Gas embolism is a medical condition leading to the blockage of blood flow in the microvasculature by gas bubbles. While reported as rare, gas embolism often has devastating, fatal physiological consequences. Despite this acute importance, the genesis and evolution of air bubbles in blood vessels under different physiological conditions, such as blood viscosity and blood flow rate, is still understudied, largely because of difficult experimentation and in situ visualization. The objective of this work was to study the gas embolism phenomenon in vitro, using a microfluidic system that mimicked the architecture of microvasculature. The microfluidic systems comprised linear channels with two different air inlet types, namely, T- and Y-junctions with three different widths (20 µm, 40 µm, and 60 µm), and a 30 µm width honeycombed network with three bifurcation angles (30°, 60°, and 90°). Three synthetic liquids equivalent to 0%, 20%, and 46% hematocrit that mimicked the physiological blood viscosity and hematocrit concentrations were used. Our results show that: (i) 20 µm and 40 µm width channels had an elevated risk of gas embolism due to wide fluctuations in the total slug sizes; (ii) the resistance to the flow of air bubbles increased with the increase in the equivalent concentration of hematocrit; (iii) gas bubbles causing blockages and dampening of the flow velocity were frequently observed in 20 µm channels, and lastly (iv) increased risk of gas embolism was observed in the honeycomb architecture with 60° and 30° bifurcations. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures opens the possibility of studying this medical condition with high reproducibility and impacts the fact-based medical guidelines for preventing or mitigating iatrogenic occurrences.
ARTICLE | doi:10.20944/preprints201709.0042.v1
Subject: Keywords: fat embolism syndrome (FES); autophagy; rapamycin; rat model
Online: 11 September 2017 (09:59:48 CEST)
As a high fatal disease, fat embolism syndrome is complication, which brought great pain to patient and their family served as a serious social burden. The mechanism of FES remains unclear. Autophagy controls the cell survival and homeostasis by removing the mis-folded proteins and damaged organelles as well as intracellular pathogens through a lysosomal degradation pathway. Increasing research documented that autophagy was wildly involved in variety of human diseases and had huge therapeutic potential. In our study, we first established the rat model of FES with the liquid fat by tail vein injection. We observed the up-regulated MPO expression and activity, increased Wet-to-Dry (W/D) lung weight, promoted quantity of fat granules, and the dominant disorder in the lung rat model of FES, compared to the control group. These observations demonstrated that we successfully build the rat model of FES. Then, we sought to dissect the role of the autophagy in the rat model of FES. The western blots analysis showed that the autophagy was inhibited in the rat model of FES constructed with liquid fat. Furthermore, Rapamycin could restore the repression of autophagy in rat model of FES. These investigations illustrated that autophagy was involved in FES. In addition, our experiments showed that Rapamycin could alleviate the symptoms of FES. Taken together, our study demonstrated the participation of autophagy in FES and further, as a potential therapeutic target, the modulation of autophagy could affect the symptom of rat model of FES.
REVIEW | doi:10.20944/preprints201609.0092.v1
Subject: Materials Science, Biomaterials Keywords: PMMA; bone cement; cardiac embolism; cement leakage; viscosity
Online: 26 September 2016 (10:34:26 CEST)
Percutaneous vertebroplasty procedure is of major importance, given the significant increasing aging population and higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main features of PMMA bone cement on the heart, and the extent of influence of materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case report.
REVIEW | doi:10.20944/preprints202208.0027.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: acute pulmonary embolism; dilemmas; therapeutic treatment; recommendations; clinical application
Online: 2 August 2022 (03:12:56 CEST)
Pulmonary thromboembolism is a very common cardiovascular disease, with a still high mortality rate. Despite the clear guidelines, this disease still represents a great challenge both in diagnosis and treatment. Heterogeneous clinical picture, often without pathognomonic signs and symptoms, represents a huge differential diagnostic problem even for experienced doctors. The decision on the therapeutic regimen also represents a major dilemma in the group of patients who are hemodynamically stable at initial presentation and have signs of right ventricular (RV) dysfunction proven by echocardiography and positive biomarker values (pulmonary embolism of intermediate-high risk). Studies have shown conflicting results about the benefit of using fibrinolytic therapy in this group of patients until hemodynamic decompensation, due to the risk of major bleeding. The latest recommendations give preference to new oral anticoagulants (NOACs) compared to vitamin K antagonists (VKA), except for certain categories of patients (patients with antiphospholipid syndrome, mechanical valves, pregnancy). When using oral anticoagulant therapy, special attention should be paid to drug-drug interactions, which can lead to many complications, even to the death of the patient. Special population groups such as pregnant women, obese patients, patients with antiphospholipid syndrome and cancer represent a great therapeutic challenge in the application of anticoagulant therapy. In these patients, not only the effectiveness of the drugs must be taken into account, but great attention must be paid to their safety and possible side effects, which is why a multidisciplinary approach is emphasized in order to provide the best therapeutic option.
ARTICLE | doi:10.20944/preprints202107.0109.v1
Subject: Medicine & Pharmacology, Allergology Keywords: coagulation impairment; international normalised ratio; mortality; pulmonary embolism; thrombosis
Online: 5 July 2021 (15:36:32 CEST)
Pulmonary embolism (PE) is one of the leading causes of cardiovascular mortality, therefore new parameters regarding risk stratification are sought after. In patients admitted for acute PE we investigated associations between the initial coagulation impairment, expressed by prothrombin time international normalised ratio (INR), and parameters reflecting PE severity. Furthermore, in-hospital, 30-day and long-term mortality were also evaluated. The analysis included 848 patients who were divided into two groups: with normal INR≤1.2, and elevated INR>1.2 (252 patients, 29.7%). The group with elevated INR presented higher incidence of tachycardia and lower systolic blood pressure, higher CRP, d-dimer, and NT-proBNP. This group presented higher estimated systolic pulmonary artery pressure (49 IQR39-62mmHg vs 43 IQR32-53mmHg, p<0.001) and shorter pulmonary artery acceleration time (65 IQR55-85ms vs 81 IQR63-102ms; p<0.001). Patients with elevated INR had more often a sPESI of 1 or higher (78%vs60%, p=0.003). Cox regression model revealed that age, leukocyte level, SBP, neoplasm, and INR are associated with higher risk of death (p<0.001). Finally, elevated INR was associated with higher in-hospital (13%vs3%; p<0.001), 30-day (19%vs6%; p<0.001), and long-term mortality (p<0.001). Summing up, elevated INR on admission is frequent in patients with PE, reflects worse clinical condition and is related to PE severity and prognosis.
ARTICLE | doi:10.20944/preprints202004.0345.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: COVID-19; venous thrombosis; pulmonary embolism; venous thromboembolism; anticoagulants; mortality
Online: 19 April 2020 (13:08:16 CEST)
Coronavirus disease 2019 (COVID-19) can lead to systemic coagulation activation and thrombotic complications. We investigated the incidence of objectively confirmed venous thromboembolism (VTE) in 198 hospitalized patients with COVID-19 in a single-center cohort study. Seventy-four patients (37%) were admitted to the intensive care unit (ICU). At time of data collection, 58 (29%) were still hospitalized and 14% had died. During a median follow-up of 5 days (IQR, 3-9), 33 patients (17%) were diagnosed with VTE of whom 22 (11%) had symptomatic VTE, despite routine thrombosis prophylaxis. The cumulative incidences of VTE at 7 and 14 days were 15% (95% CI, 9.3-22) and 34% (95% CI, 23-46), respectively. For symptomatic VTE, these were 11% (95% CI, 5.8-17) and 23% (95% CI, 14-33). VTE appeared to be associated with death (adjusted HR, 2.9; 95% CI, 1.02-8.0). The cumulative incidence of VTE was higher in the ICU (25% at 7 days 95% CI, 15-36, and 48% at 14 days, 95% CI, 33-61) than on the wards (any VTE and symptomatic VTE 6.5 % at 7 days (95% CI, 1.5-17) and 10% at 14 days (95% CI, 2.9-24)).The observed risk for VTE in COVID-19 is high, particularly in ICU patients, which should lead to a high level of clinical suspicion and low threshold for diagnostic imaging for DVT or PE. Future research should focus on optimal diagnostic and prophylactic strategies to prevent VTE and potentially improve survival.
REVIEW | doi:10.20944/preprints202303.0024.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: COVID-19; SARS-CoV-2 infection; pulmonary in situ thrombosis; embolism; immunothrombosis; inflammation; coagulopathy
Online: 1 March 2023 (11:37:10 CET)
COVID-19, the infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is frequently associated with pulmonary thrombotic events, especially in hospitalised patients. Severe SARS-CoV-2 infection is characterized by a proinflammatory state and an associated disbalance in hemostasis. Immune pathology analysis supports the inflammatory nature of pulmonary arterial thrombi composed by white blood cells, especially neutrophils, CD3+ and CD20+ lymphocytes, fibrin, red blood cells and platelets. Immune cells, cytokines, chemokines and the complement system are key drivers of immunothrombosis, as they induce the damage of endothelial cells and initiate pro-inflammatory and pro-coagulant positive feedback loops. Neutrophil extracellular traps induced by COVID-19-associated “cytokine storm”, platelets, red blood cells, and coagulation pathways close the inflammation-endotheliopathy-thrombosis axis, contributing to SARS-CoV-2 associated pulmonary thrombotic events. The hypothesis of immunothrombosis is also supported by the minor role of venous thromboembolism, chest CT imaging data showing peripheral blood clots associated with inflammatory lesions and the high incidence of thrombotic events despite routine thromboprophylaxis. Understanding the complex mechanisms behind COVID-19-induced pulmonary thrombosis will lead to future combination therapies for hospitalised patients with severe disease, that would target the crossroads of inflammatory and coagulation pathways.
REVIEW | doi:10.20944/preprints202208.0190.v1
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: iron-deficient anemia; IDA; stroke; cerebral venous thrombosis; brain MRI; aortic thrombosis; pulmonary embolism; embolic pattern
Online: 10 August 2022 (04:31:26 CEST)
Background: Anemia is one of the most frequent diseases worldwide, affecting a third of the general population. Anemia in general and in particular, iron-deficient anemia (IDA), has been associated to a higher risk of thrombotic manifestations, including ischemic stroke and cerebral venous thrombosis (CVT), as well as systemic extra cerebral arterial and venous thrombosis. Despite these data, anemia is seldom considered as an etiological factor of stroke. Methods: An individual case encompassing all known neurovascular and systemic arterial and venous thrombotic manifestations related to IDA is presented with the focus on clinical reasoning issues in the diagnostic pathways, starting from the neuroradiological signs. The main questions have been identified and addressed in a narrative review of the most relevant data in the literature from a pragmatic and clinical viewpoint. Results and Discussion: The presented case concerns a 46 years old man admitted to the Stroke Unit because of acute is-chemic stroke with multiple thrombi in large intracranial and extracranial vessels, multifocal ischemic lesions in several arterial territories and the concurrent finding of asymptomatic CVT, pulmonary embolism with lung infarction and aortic thrombosis. An extended diagnostic work-up excluded the main etiologies (arterial dissection, cardiac embolism, genetic and acquired prothrombotic disorders, as cancer and antiphospholipid syndrome), except for a severe IDA, such as to require blood transfusions followed by anticoagulant therapy for the several thrombotic manifestations. Neuroimaging and systemic vascular findings have been analyzed and the main issues proposed by the case in the diagnostic pathway have been identified and discussed in a pragmatic clinical road map reviewing the data provided by the literature. Conclusions: IDA is a common but treatable condition that, independently or synergically, may increase the risk of thrombotic events. The diagnostic and therapeutic approach has not yet defined and each case should be individually addressed in a pragmatic clinical road map.
ARTICLE | doi:10.20944/preprints202204.0163.v1
Subject: Mathematics & Computer Science, Artificial Intelligence & Robotics Keywords: artificial intelligence; deep learning; image-to-image translation; dual-energy computed tomography; pulmonary embolism; emergency radiology
Online: 18 April 2022 (09:45:00 CEST)
Detector-based spectral CT offers the possibility of obtaining spectral information from which discrete acquisitions at different energy levels can be derived, yielding so-called virtual monoenergetic images (VMI). In this study, we aimed to develop a jointly optimized deep learning framework based on dual-energy CT pulmonary angiography (DE-CTPA) data to generate synthetic monoenergetic images (SMI) for improving automatic pulmonary embolism (PE) detection in single-energy CTPA scans. For this purpose, we used two data sets: our institutional DE-CTPA data set D1 comprising polyenergetic arterial series and the corresponding VMI at low-energy levels (40 keV) with 7,892 image pairs, and a 10% subset of the 2020 RSNA Pulmonary Embolism Detection Challenge data set D2, which consisted of 161,253 polyenergetic images with dichotomous slice-wise annotations (PE/no PE). We trained a fully convolutional encoder-decoder on D1 to generate SMI from single-energy CTPA scans of D2, which were then fed into a ResNet50 network for training of the downstream PE classification task. The quantitative results on the reconstruction ability of our framework revealed high-quality visual SMI predictions with reconstruction results of 0.984 ± 0.002 (structural similarity) and 41.706 ± 0.547 dB (peak-signal-to-noise ratio). PE classification resulted in an AUC of 0.84 for our model, which achieved improved performance compared to other naive approaches with AUCs up to 0.81. Our study stresses the role of using joint optimization strategies for deep learning algorithms to improve automatic PE detection. The proposed pipeline may prove to be beneficial for computer-aided detection systems and could help rescue CTPA studies with suboptimal opacification of the pulmonary arteries from single-energy CT scanners.
ARTICLE | doi:10.20944/preprints202210.0100.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: screening after pulmonary embolism; chronic thromboembolic pulmonary disease; chronic thromboembolic pulmonary hypertension; diagnostic work-up of post-pulmonary syndrome
Online: 9 October 2022 (02:09:20 CEST)
Background: The annual mortality of patients with untreated chronic thromboembolism pulmonary hypertension (CTEPH) is approximately 50% unless a timely diagnosis is followed by adequate treatment. In pulmonary embolism (PE) survivors with functional limitation the diagnostic work-up starts with echocardiography. It is followed by lung scintigraphy and right heart catheterization. However, noninvasive test providing diagnostic clues to CTEPH, or ascertain this diagnosis as very unlikely, would be extremely useful since the majority of post PE functional limitations is caused by deconditioning. Methods: Patients after acute PE underwent a structured clinical evaluation with electrocardiogram, routine laboratory tests including NT-proBNP and echocardiography. The aim of study was to verify whether the parameters from echocardiographic or perhaps electrocardiographic examination and NT-proBNP concentration best determine the risk of CTEPH. Results: A total (n = 261, male n = 123) patients after PE were included into the study, in group of 155 patients (59.4%) with reported functional impairment 13 patients (8.4%) had CTEPH and 7 PE survivors had chronic thromboembolic pulmonary disease (CTEPD) (4,5%). Echo parameters differed significantly between CTEPH/CTEPD cases and other symptomatic PE survivors. Patients with CTEPH/CTEPD had also higher level of NT-proBNP (p = 0.022) but concentration of NT-proBNP above 125 pg/ml did not differentiate patients with CTEPH/CTEPD (p>0.05). Additionally, proportion of patients with right bundle brunch block registered in ECG was higher in group with CTEPH/CTED (23.5% vs. 5.8%, p = 0.034) but there were no differences between other ECG characteristics of right ventricle overload. Conclusion: Screening for CTEPH/CTEPD should be performed in patients with reduced exercise tolerance compared to pre PE period, It is not effective in asymptomatic PE survivors. Patients with CTEPH/CTED had predominantly abnormalities indicatingchronic thromboembolism in the echocardiographic assessment. NT-proBNP and electrocardiographic characteristics of right ventricle overload proved to be insufficient in predicting CTEPH/CTEPD development.
ARTICLE | doi:10.20944/preprints202205.0145.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: abdominal aorta; arterial embolism; B-Flow sonography; contrast enhanced ultrasound; endovascular aortic repair; flashlight sign; peripheral arteries; wall adherent floating structures
Online: 11 May 2022 (03:44:41 CEST)
This study aimed on evaluating the potential diagnostic value of a novel, sonographic, B-Flow Imaging (BFI)-based sign (“flashlight sign”, FLS) for the detection of wall-adherent, floating arterial structures (WAFAS). The FLS, characterized by a fast moving, very bright, intraluminal signal was detected in 28 patients with WAFAS. We divided this cohort into three subgroups, depending on the affected vascular segments: (1) peripheral arteries (n = 10), (2) native abdominal aorta (n = 8), and (3) abdominal aorta after endovascular aortic repair (EVAR; n = 10). Clinical characteristics were analyzed and BFI-findings were compared with contrast enhanced ultrasound (CEUS) and computed tomography angiography (CTA). Seven patients (25%) suffered from arterial embolism downstream to the FLS (EVAR, n = 4; native abdominal aorta, n = 1; peripheral arteries, n = 2). WAFAS of the abdominal aorta (native or after EVAR), as indicated by the FLS, were visible by CEUS and CTA in 60% and 93.3%, respectively. Based on the so far largest cohort of patients with WAFAS, we propose a clinically useful, BFI-based sonographic sign for detection of these so far underrated arterial pathologies in the abdominal aorta and the peripheral arteries.