Blood Flow Stasis Research Articles

A latent bleeding complication in ipsilateral common femoral puncture involving delayed diagnosis: a case report

BackgroundThe trans femoral ipsilateral approach is often adopted for endovascular treatment (EVT) for better steerability of guidewires or better device deliverability. However, contrary to the trans femoral contralateral approach, ipsilateral antegrade puncture sometimes causes peculiar bleeding complications.Case presentationA 76-year-old female underwent EVT for chronic occlusion of the left superficial femoral artery (SFA) via the ipsilateral antegrade approach. After guidewire passage, we inflated the drug-coated balloons, but angiography showed blood flow stasis at the mid segment of the SFA. We also ensured prolonged balloon inflation, which resulted in favorable blood flow. While trying to ensure hemostasis, the blood pressure remained decreased, but neither bleeding nor superficial hematoma were observed at the puncture site. After hemostasis was achieved, we removed the surgical drape and noticed a swelling in the mid-portion of the thigh, distant from the puncture point. We then approached the left common femoral artery (CFA) contralaterally. Angiography showed continuous bleeding from a little bit distally to the sheath insertion point that was spreading through an intramuscular space. We stopped the bleeding with balloon tamponade inside the CFA. Angiography after hemostasis demonstrated blood flow stasis at the mid-segment of the SFA, similarly as that seen before. We confirmed compression of the SFA by a large hematoma using both intra- and extra- vascular ultrasound. Therefore, we deployed a self-expandable stent at the compressed SFA position. Finally, we achieved favorable blood flow on angiography.ConclusionWe encountered a case that latent bleeding unrecognized in the surgical field persisted while prolonged inflation of DCB was conducted at just proximal SFA. We could have avoided bailout stenting by noticing the bleeding incident in a timely manner. Prediction and prevention are essential for all kinds of procedural complications in EVT.

A neoteric approach to understanding thrombosis

Pathophysiology of thrombosis. Thrombosis, a leading cause of morbidity and mortality worldwide, results from an imbalance between procoagulant, anticoagulant, and fibrinolytic factors. Virchow?s triad - endothelial injury, stasis of blood flow, and hypercoagulability - has long been the cornerstone for understanding thrombosis. However, evolving knowledge has refined our interpretation of how these factors contribute to venous and arterial thrombosis. Arterial thrombosis. Historically, arterial and venous thromboses were viewed as distinct pathophysiological entities. Over the past two decades, research has highlighted the complexity of etiopathogenesis of the thrombotic process, recognizing mutual risk factors offering a more comprehensive understanding the pathophysiological mechanism behind these diseases. Venous thrombosis. Recent insights focus on thrombotic potential, defined as an individual?s susceptibility to thrombosis resulting from a combination of congenital and acquired risk factors.. It has become clear that the interaction of these factors is not merely additive but synergistic, significantly increasing the risk of thrombosis. The significant social impact of thrombosis underscores the necessity of thoroughly understanding its underlying mechanisms to develop effective preventive and therapeutic strategies.

COVID-19 shed light on Virchow's law of thrombosis.

Virchow's law of thrombosis states that thrombosis in a vessel occurs as a combination of the following: (i) injury to the vessel wall, (ii) stasis of blood flow, and (iii) blood hypercoagulability. Injury to the wall includes infection/inflammation and/or injury to the resident cells of the wall. We postulate that in COVID-19, the SARS-CoV-2 virus directly infects the alveolar type II cell or directly or indirectly infects/injures the pericyte, promoting inflammation and interaction with endothelial cells, thereby causing a cascade of events leading to our observation that thrombosis occurred within the walls of the pulmonary vessels and not in the lumen of the vascular circulation.

Model construction and thrombolytic treatment of rat portal vein thrombosis.

To construct a stable rat portal vein thrombosis (PVT) model and explore the time window of urokinase thrombolytic therapy on this basis. Constructing a rat PVT model by combining anhydrous ethanol disruption of portal endothelium with stasis of blood flow. Forty-eight rats after PVT modeling were divided into control group and experimental group, with 24 rats in each group. The experimental and control groups were given urokinase treatment and saline tail vein injection, respectively. The two groups of rats were observed and compared for PVT formation at 1, 3 and 5 days after modeling, respectively. A stable rat PVT model was successfully constructed. No significant differences were found in PVT length, portal vein wet weight, and percentage of luminal occlusion area in the control rats at 1, 3, and 5 days after successful modeling (P > 0.05). Compared with control rats 1 day after modeling, the percentage of non-organized thrombus luminal area was significantly decreased (P < 0.0001), and the percentage of organized thrombus luminal area was significantly increased (P < 0.0001) in the PVTs of control rats at 3 and 5 days after modeling. After thrombolytic treatment with urokinase, plasma fibrinogen (FBG) levels were significantly decreased in the experimental group of rats compared with the control group (P < 0.0001), and plasma D-dimer (D2D) levels were significantly increased in the experimental group of rats compared with the control group (P < 0.0001). In addition, we observed prolongation of prothrombin time (PT) in the experimental group at 1, 3 and 5 days after modeling compared to the control group (P = 0.0001). Compared with the control group, portal vein wet weight and PVT length were significantly decreased in the experimental group of rats at 1 day after modeling (P < 0.05), whereas these differences were not found in the two groups of rats at 3 and 5 days after modeling (P > 0.05). The percentage of non-organized thrombus area in the experimental group was significantly decreased compared with that in the control group at 1, 3, and 5 days after modeling (P < 0.05), whereas there was no significant difference in the percentage of lumen area of organized thrombus between the two groups (P > 0.05). The method of producing a rat PVT model by destroying the endothelium of the portal vein by anhydrous ethanol combined with blood flow stasis is feasible and reproducible. In addition, the optimal time window for thrombolysis in the treatment of PVT in rats using urokinase is the early stage of thrombosis, when the fibrin content is highest.

Changes in cerebral hemodynamic parameters for patients with encephalopathies of different genesis

Mental function impairment is a common sign of encephalopathies, which various factors, including neurological disorders and cerebral hemodynamics, can cause.The purpose of the study was to establish changes in cerebral hemodynamic parameters in patients with encephalopathies of various origins.Material and methods. 520 patients with chronic traumatic encephalopathy (CTE, n=145), vascular encephalopathy in chronic brain ischemia (CVE, n=145), chronic alcoholic encephalopathy (CAE, n=102) and post-infectious encephalopathy (PIE, n=128) were examined. The patients were receiving inpatient treatment on the basis of the communal non-profit enterprise "Ternopil Regional Clinical Psychoneurological Hospital" during the period of 2021-2022. The cerebral blood flow was assessed using transcranial doppler scanning of intracranial and extracranial brachiocephalic vessels on a Philips HDI device.Research results. The most frequent disorders of cerebral hemodynamics in patients with CTE are the following: insufficient blood flow (44.83%), angiospasm (44.14%) and stenosis (40.69%); in patients with CVE – stenosis (67.59%), insufficient blood flow (66.21%) and venous stasis (64.83%); in patients with CAE – insufficient blood flow (32.35%), angiospasm (31.37%) and venous stasis (30.39%); in patients with PIE - angiospasm (45.31%), blood flow insufficiency (37.50%) and vertebro-basilar insufficiency (30.47%). Comparing the parameters of cerebral hemodynamics in patients with encephalopathies of various genesis, it was established that angiospasm in patients with CVE was recorded more often (by 23.11%) than in patients with CAE. A similar trend was noted in patients with CTE and PIE relative to the CAE group. The frequency of registration of blood flow insufficiency in patients with CVE probably exceeded the data of groups of CTE, CAE, and PIE (by 21.38, 33.86, and 28.71%, respectively). At the same time, the presence of changes within two distribution zones - carotid cerebral and vertebral-basilar in patients with CVE probably exceeded the data of the CAE and PIE groups. Regarding the comparison of the characteristics of stenoses, the frequency of detection of this phenomenon in patients with CTE probably exceeded the data of the CTE, CAE, and PIE groups (by 26.90, 53.86, and 64.46%, respectively). At the same time, the proportion of patients with significant stenosis in the CTE group probably exceeded the data of the CVE, CAE and PIE groups. The highest frequency of registration of venous stasis was established in patients with CTE (64.83%), which probably exceeded the data of the CTE, CAE and PIE groups. Vertebro-basilar insufficiency was not detected in patients with CAE, and in the PIE group its frequency of registration was 14.61% higher than the data of the CVE group and 18.06% higher than the data of the CTE group.Conclusions. The obtained results indicate the heterogeneity and polymorphism of the parameters of cerebral hemodynamics in patients with encephalopathies of various genesis, which requires further research to find possible relationships between them and cognitive dysfunction.

Principles Treatment Of Septic Arthritis Of The Knee: A Brief Review

Septic arthritis is an emergency condition in which infection occurs in the synovial joints, resulting in the formation of pus in the synovial spaces. Theincidence of septic arthritis increases in patients with an increased risk such as rheumatoid arthritis. The etiology of septic arthritis is mainly bacterial. Risk factors include iatrogenic procedures (surgery, implant placement, joint puncture) and systemic conditions (diabetes mellitus, rheumatoid arthritis receiving immunosuppressants, etc). Pathophysiology of septic arthritis is due to blood flow stasis in metaphyseal areas especially in children and intraarticular minimal blood circulation. Clinical pictures include sudden onset of fever, malaise, localized pain in the infected joint, joint swelling, and reduced range of motion. Examination for septic arthritis is a physical examination carried out are inspection (see), palpation (touch), and movement. supporting examinations include blotestsest, PCR, radiological and joint fluid tests. Treatments include non-pharmacological such as rest and physical therapy, pharmacological the form of antibiotics, and surgicaltherapy such as drainage incision. This study is a brief review of the current Principles Treatment Of Septic Arthritis Of The Knee. The reference to this review was taken from the latest journal up to 5 years and the latest book up to 10 years.

The novel left atrial appendage strain parameters are associated with thrombosis risk in patients with non-valvular atrial fibrillation.

We sought to explore a novel left atrial appendage (LAA) strain parameter which could represent the cumulative adverse impact of chronic Atrial fibrillation (AF) on the LAA function, and the relationship between the LAA strain parameter and thrombosis risk in patients with non-valvular AF. We enrolled 268 patients with non-valvular AF and 58 sinus rhythm subjects who underwent transesophageal echocardiography in the study. LAA longitudinal strain amplitude (LAA LSA) was defined as the sum of the value of the maximum positive peak strain (LAA PLS) and the absolute value of the minimum negative peak strain (LAA NLS). Dense spontaneous echo contrast (SEC) was defined as grade 3 or 4 SEC. Compared to sinus rhythm group, the global LAA strain parameters were significantly lower in paroxysmal AF (n = 148), and the lowest of them were found in persistent AF (n = 120), which suggested that the global LAA strain parameters could evaluate LAA function in sinus rhythm, paroxysmal AF and persistent AF. Compared with patients in AF without SEC/thrombus (n = 113), the regional and global LAA strain parameters were significantly depressed in AF with SEC/thrombus (n = 155). Multivariate logistic regression analyses showed that LAA global LSA (OR 0.768; 95% CI:0.569, 0.970; p = 0.027) was an independent predicter of the SEC/thrombus. Compared with patients in AF without dense SEC or thrombus (n = 210), the regional and global LAA strain parameters were significantly impaired in the patients with dense SEC/thrombus(n = 58). LAA global LSA (AUC 0.884) had the best predictable accuracy for dense SEC or thrombus, and outperformed LAA PLS, LAA NLS, CHA2DS2-VASc score and conventional LAA functional parameters that have been used in the evaluation blood flow stasis in LAA. LAA LSA showed excellent interobserver and intra-observer agreement beyond LAA PLS and LAA NLS. The novel LAA strain parameters, which were feasible and reproducible parameters for evaluation LAA mechanic function, had good predictive accuracy for blood flow stasis in LAA beyond conventional LAA functional parameters.

Lower Extremity Reconstruction with Anterolateral Thigh Free-Flap Anastomoses: A Computational Fluid Dynamic Analysis.

The anterolateral thigh free flap is an option for repairing soft tissue defects of the distal lower extremity. This flap uses the descending branch of the lateral circumflex femoral (LCF) artery as the flap vessel. The recipient vessel in these flaps is often the anterior tibial (AT), posterior tibial (PT), or peroneal (P) arteries. Computational fluid dynamic (CFD) evaluation of anastomoses between these vessels can optimize outcomes. Thirty-eight CFD models were created to model end-to-side (ETS) and end-to-end (ETE) anastomoses for lower extremity reconstruction. Seven out of thirty-eight models represented ETS anastomoses between the LCF and AT arteries with varying anastomotic angles. Nine out of thirty-eight models represented 45-degree ETS anastomoses between varying diameters of the LCF and AT, PT, and P arteries. Nine out of thirty-eight models represented stenosis on the flap vessel and recipient vessel, pre- and post-bifurcation. Nine out of thirty-eight models represented ETE anastomoses, rather than ETS, with varying vessel diameters. Four out of thirty-eight models represented ETE anastomoses with varying regions and levels of stenosis. Stasis of blood flow in ETS models increased as anastomotic angle increased in a logarithmic relationship (R 2 = 0.918). Flow was optimized overall as flap and recipient vessel diameters approached one another. In ETS models, flap vessel and postbifurcation recipient vessel stenosis were found to substantially increase stasis. Selection of flap and recipient vessels with similar diameters can optimize outcomes in microvascular anastomoses. In the context of lower extremity reconstruction with the ALT flap, the PT artery can be recommended as a first-line recipient vessel due to its similar vessel caliber to the LCF and relative ease of surgical access compared with the P artery. Avoidance of areas of stenosis is recommended to ensure laminar flow and reduce the operative difficulty associated with performing anastomoses on nonpliable arteries. Striving for increased acuity of anastomotic angles is recommended to optimize the flow in ETS microvascular anastomoses.

Benefits of early mobilization in patients with deep venous thrombosis: a scope review

Objective: Deep venous thrombosis (DVT) is a blood flow obstruction caused by the formation of a thrombus in deep system veins, with higher prevalence in lower limbs. Bed restriction has been indicated in patients with DVT in order to avoid pulmonary embolism caused by displacement of the thrombus. However, immobility has recently been considered a risk factor for DVT, not only due to blood flow stasis, but also by secondary complications as muscle atrophy and weakness. Objective was to review the possible benefits of early mobilization in patients with DVT in the intensive care unit. Methods: A scope review of literature was conducted. The following keywords were used: deep venous thrombosis, early mobilization and physical therapy. The search was made on Pubmed and Scielo databases. Results: 20 studies were found and 7 articles were included in the review using the exclusion criteria. Conclusion: Early mobilization association with anticoagulation and compression was described as essential in the treatment of DVT, reducing deleterious effects of immobility, pain, edema, and promoting quality of life improvement.

Usefulness of a Novel Vascular Access Management Method Using a Laser Blood Flowmeter

Introduction: Various methods for vascular access (VA) management have been studied. We investigated the usefulness of a new, simple, and quantitative VA management method using the Pocket LDF® laser blood flowmeter (hereinafter “LDF”) that noninvasively measures peripheral circulation flow. Methods: Peripheral circulation flow was measured in 82 patients (43 men) on maintenance hemodialysis with an arteriovenous fistula (AVF). The shunt symmetry index (SSI) was calculated as peripheral circulation flow in the AVF limb divided by that in the non-AVF limb. SSI was used for microcirculation evaluation and also compared by AVF site. Patients undergoing vascular access interventional therapy (VAIVT) underwent ultrasound evaluation (Doppler ultrasonography) of the AVF and SSI measurement before and after VAIVT. SSI was compared between those who did and did not require VAIVT, and the cutoff value for SSI was determined by receiver operating characteristic curve (ROC) analysis. Results: As many as 86% of the patients who were measured peripheral circulation flow had SSI <1.0, which indicates that AVF reduced peripheral circulation flow. All patients who underwent VAIVT showed a decrease in SSI to <1.0 after VAIVT, probably due to improvement of stenosis. SSI differed significantly between patients who did and did not require VAIVT (1.20 ± 0.49 vs. 0.65 ± 0.33, p < 0.001), which indicates that SSI is affected by the presence of stenosis in the proximal vein of the VA anastomosis. In patients with SSI ≥1.0, stenosis of the proximal vein of the AVF caused stasis of blood flow, resulting in increased peripheral blood flow. AVF site seems to have no impact on peripheral circulation flow. The SSI cutoff value for the screening of proximal vein stenosis was 1.06 (sensitivity: 0.69, specificity: 0.93, area under the curve: 0.81). Conclusion: Based on the ROC analysis, we recommend considering AVF ultrasound for SSI >1.06. Our results suggest the usefulness of the described VA management method using the LDF.

Challenges for anaesthesia for robotic-assisted surgery in the elderly

Steep and reverse Trendelenburg positions are often used in robotic-assisted surgery (RAS) to improve surgical access. The elderly are particularly vulnerable to the cardiovascular effect of the combination of pneumoperitoneum and these extreme positions. Falls in both cardiac output (CO) and mean arterial pressure (MAP) caused by pneumoperitoneum are enhanced in reverse Trendelenburg. Hypotension with dangerous cerebral and myocardial hypoperfusion may occur. Caution should be exercised in patients with low cardiac reserve and the degree of peri-operative risk should dictate the level of haemodynamic monitoring employed. The effects of pneumoperitoneum on CO are less pronounced in the standard Trendelenburg position due to gravity, but head-down combined with pneumoperitoneum can increase both MAP and systemic cardiovascular resistance. However, in patients with impaired myocardial contractility, the head-down position may lead to cardiac failure. In addition, the adverse respiratory effects of pneumoperitoneum, which include reduction of pulmonary compliance and functional residual capacity, may be exacerbated by steep Trendelenburg. At the same time, hypercarbia resulting from CO2 insufflation can lead to an increase in stasis of brain blood flow and intracranial pressure with possible repercussions on cognitive functions in the elderly. Another problem is the increase in intra-ocular pressure during steep Trendelenburg, and injury to the optic nerve has been reported after robot-assisted prostatectomy. Finally, strategies to use the lowest possible pneumoperitoneum pressure are considered to reduce possible complications. Moreover, the extreme positions should be limited only to the time strictly necessary for surgery and should be avoided in high-risk patients.

Evaluation of hemodynamic effects of different inferior vena cava filter heads using computational fluid dynamics.

Inferior vena cava (IVC) filters are used to prevent pulmonary embolism in patients with deep vein thrombosis for whom anticoagulation is unresponsive. The head is a necessary structure for an Inferior vena cava filter (IVCF) in clinic use. At present, there are various head configurations for IVCFs. However, the effect of head pattern on the hemodynamics of IVCF is still a matter of unclear. In this study, computational fluid dynamics is used to simulate non-Newtonian blood flows around four IVCFs with different heads inside an IVC model, in which the Denali filter with a solid and hooked head is employed as a prototype, and three virtual variants are reconstructed either with a no-hook head or with a through-hole head for comparison. The simulation results show that the through-hole head can effectively avoid the recirculation region and weaken the blood flow stasis closely downstream the IVCF head. The shape change of the filter head has no significant effect on the blood flow acceleration inside the IVCF cone as well as little influence on the wall shear stress (WSS) distribution on the filter wire surface and IVC wall. The structure pattern of filter head greatly affects the flow resistance of its own. However, the flow drag of filter head only occupies a small proportion of the total resistance of IVCF. Therefore, to reduce the flow resistance of an IVCF should optimize its whole structure.

Pharmacokinetic study comparing doxorubicin concentrations after chemoembolization or intravenous administration in dogs with naturally occurring nonresectable hepatic carcinoma.

BackgroundChemoembolization is a viable treatment option for patients with nonresectable hepatic carcinoma (HC) and may allow delivery of chemotherapeutic drugs with decreased systemic toxicity.Hypothesis/ObjectiveCompare the serum concentrations of doxorubicin after chemoembolization or IV administration in the same patient. We hypothesized that locoregional delivery may result in increased tumor chemotherapeutic drug concentrations, reflected by decreased measurable serum drug concentrations. Adverse hematological events were hypothesized to be decreased after locoregional delivery.AnimalsSeventeen client‐owned dogs with incompletely resectable HC.MethodsProspective, single‐arm clinical trial. Drug‐eluting bead transarterial chemoembolization was performed to varying levels of blood flow stasis (NO STASIS, STASIS). Intravenous doxorubicin (IVC) subsequently was administered in selected patients. Systemic exposure was quantified by area under the serum doxorubicin concentration time curve (AUC), maximum serum doxorubicin concentration (Cmax), and time doxorubicin was last above the limit of quantitation (Tlast). Nadir test results after treatments were used to evaluate adverse hematological events.ResultsThirteen NO STASIS treatments, 15 STASIS treatments, and 9 IVC treatments were performed. Maximum serum doxorubicin concentration, AUC, and Tlast were significantly lower when comparing NO STASIS or STASIS to IVC treatments. Of the patients with nadir results available, no adverse hematological events were observed after NO STASIS or STASIS treatments. Two patients developed adverse hematological events after IVC treatment.Conclusions/Clinical RelevanceDrug‐eluting bead transarterial chemoembolization offers a viable treatment option for patients with incompletely resectable HC with the potential for increased local tumor doxorubicin concentrations, decreased systemic chemotherapeutic exposure, and fewer adverse hematological events.

Development of an In-bed Exercise Program to Prevent Postoperative Complications that can be Performed Immediately after Surgery: Experimental Study of Healthy Elderly Participants

Background:Continuous postoperative bed rest causes decreased peripheral perfusion stasis of venous blood flow in the lower extremities and, decreased intestinal peristalsis and muscle mass. We aimed to develop an exercise program that could be carried out immediately after surgery and verified its usefulness in a preliminary study targeting healthy elderly individuals. Methods: Healthy elderly individuals were included in this prospective study. This comparative study was conducted from November 2021 to March 2022. The program consisted of grip movement of the fingers, active movement of the lower limbs, and lower limb trunk exercises. The participants were in a supine position on the bed, exercised for about 10 minutes based on the devised program, and the perfusion index and vital signs such as SpO2, blood pressure, and pulse rate were measured for 1 h every 5 minutes. Dyspnea and feeling tired were evaluated before, immediately after, and 10 min after the exercises using unmarked new 100 visual analog scale (VAS) sheets. Results: Both the upper and lower limbs showed significant improvement in peripheral perfusion immediately after exercise and lasted for 5–10 min. The pulse rate was significantly elevated for 5 min after finishing the exercises, but blood pressure and SpO2 remained unchanged. The VAS score of feeling tired was significantly higher immediately after exercise than before exercise, and no difference was observed before and 10 min after exercise, and the VAS scores for dyspnea did not differ between the three points. Conclusion: The exercise program devised in this study was expected to improve peripheral perfusion without straining the participants in this study, targeting healthy elderly individuals. This verification provided valuable data and proved that it could be developed into an intervention study for patients undergoing surgery.

Effect of Leaflet Type and Leaflet-Stent Attachment Height on Transcatheter Aortic Valve Leaflet Thrombosis Potential

Abstract Transcatheter aortic valve replacement devices vary in leaflet material and in the height for which leaflets attach to the stented valve frame. Combinations of these features can influence leaflet dynamics, neo-sinus geometries, and fluid dynamics, thereby reducing or exacerbating the potential for blood flow stasis and leaflet thrombosis. To investigate these interconnected relationships, this study evaluated the effects of transcatheter valve leaflet type [porcine versus bovine pericardium] and the leaflet-stent attachment height (low, mid, and high) on flow stasis and potential for leaflet thrombosis. Transcatheter valve models were manufactured and tested within an aortic simulator under pulsatile left heart hemodynamic conditions. Transvalvular hemodynamics, leaflet kinematics, and flow structures were evaluated by direct measurement, high-speed imaging, and two differing techniques of particle image velocimetry. Transcatheter valves with porcine pericardial leaflets were observed to be less stiff, exhibit a lesser resistance to flow, were associated with reduced regions of neo-sinus flow stasis, and superior sinus washout times. More elevated attachments of the leaflets were associated with less neo-sinus flow stasis. These initial results and observations suggest combinations of leaflet type and stent attachment height may reduce transcatheter aortic valve flow stasis and the potential for leaflet thrombosis.

The potential of high-frequency ultrasound Dopplerography in the assessment of microcirculatory disorders in post-COVID-19 patients with a cardiovascular profile

Introduction. Patients with cardiovascular diseases have endothelial dysfunction and a higher risk of severe course of COVID-19, and thrombotic complications. Associated endotheliitis caused by virus penetration and cytokines storm leads to the release of tissue factor, the formation of excess thrombin and fibrin and thrombosis. The aim. To identify the potential of high-frequency ultrasound Dopplerography (HFUDG) for the assessment of microcirculatory disorders in post-COVID-19 patients with cardiovascular profile and to assess the microcirculatory bed condition before and after treatment with sulodexide. Materials and methods. 49 patients recovered from moderate-severe COVID-19 one month ago, aged 20–80, were examined. 24 patients, received prophylaxis with POACs for 1 month, formed group I, group II – 25 patients without prophylaxis. The nail bed of the upper limb 1st finger was examined using HFUDG and a 25 MHz sensor. Shape and spectrum of curves taken from dopplerograms were analyzed. The control examination was performed 4 weeks after therapy. Results. In patients after COVID19, depletion of spectral characteristics was revealed in comparison with dopplerograms of healthy individuals. The predominantly red part of the spectrum corresponding to the fastest particles was recorded. Slow-moving particles corresponding to the lighter part of the spectrum were nearly non-existent. In patients administrated POAC prophylaxis, amplitude indices were higher. Significant increase in D-dimer, antithrombin III, and soluble fibrin monomer complexes (SFMC) was also detected. The remaining parameters of the coagulogram were within the norm before and after treatment. After a course of sulodexide therapy, the spectral characteristics and coagulogram parameters returned to normal. Conclusion. HFUDG allows to detect stasis of capillary blood flow, the appearance of shunt blood flow corresponding to microtrombosis. Microcirculation indicators in post-COVID-19 patients improved after a course of preventive therapy with sulodexide.

4D Flow MR Imaging of the Left Atrium: What is Non-physiological Blood Flow in the Cardiac System?

Most cardiac diseases cause a non-physiological blood flow pattern known as turbulence around the heart and great vessels, which further worsen the disease itself. However, there is no consensus on how blood flow can be defined in disease conditions. Especially, in the left atrium, the fact that vortex flow already exists makes this debate more complicated. 3D time-resolved phase-contrast (4D flow) MRI is expected to be able to capture blood flow patterns from multiple aspects, such as blood flow velocity, stasis, and vortex quantification. Previous studies have confirmed that physiological vortex flow is predominantly induced by the higher-volume flow from the superior left pulmonary vein. In atrial fibrillation, 4D flow MRI reveals a non-physiological blood flow pattern, which information may add value to well-established clinical risk factors. Currently, the research target of LA analysis has also widened to lung surgeons, pulmonary vein stump thrombosis after left upper lobectomy. 4D flow MRI is expected to be utilized for many more variable diseases that are currently unimaginable.

Prone Positioning as a Potential Risk Factor for Deep Vein Thrombosis in COVID-19 Patients: A Hypothesis Generating Observation.

Aims of the study: Virchow’s triad with stasis, activated coagulation, and endothelial damage is common in SARS-CoV2. Therefore, we sought to retrospectively assess whether the duration of prone position may serve as a risk factor for deep vein thrombosis in critically ill patients. Methods: In this single center retrospective study of a tertiary referral hospital, patients with acute respiratory distress syndrome (ARDS) due to COVID-19 pneumonia admitted to critical care underwent venous ultrasound screening for deep vein thrombosis (DVT). Data on DVT diagnosis, duration of prone positioning, demographic, respiratory, and laboratory parameters were retrospectively collected and compared between DVT and non-DVT patients. Results: 21 patients with ARDS from COVID-19 pneumonia were analyzed. DVT was detected in 11 (52%) patients (76.2% male, median age 64 (58; 68.5) years, median body mass index 31 (27; 33.8) kg/m2). In patients diagnosed with DVT, median prone ventilation had been maintained twice as long as compared to patients without DVT (57 (19; 72) versus 28 (0; 56.3) h, p = 0.227) on ICU day 5 with a trend towards longer prone position time (71 (19; 104) versus 28 (0; 73) h, p = 0.06) on ICU day 7. Conclusions: Prone ventilation and constitutional factors may constitute an additional risk factor for DVT in COVID-19 patients. Since recent studies have shown that therapeutic anticoagulation does not impact the occurrence of thromboembolic events, it may be worthwhile to consider mechanical factors potentially affecting blood flow stasis in this high-risk population. However, due to the limited number of patients, our observations should only be considered as hypothesis-generating. Future studies, sufficiently powered and preferably prospective, will be needed to confirm our hypothesis.

Methods for making animal models of retinal vein occlusion

Retinal vein occlusion (RVO) is divided into branch retinal vein occlusion and central retinal vein occlusion. It is characterized by retinal vein dilatation and tortuosity, blood flow stasis, bleeding and edema. It is often accompanied by macular edema (ME) and neovascularization. Neovascular glaucoma is the most serious complications. RVO is the second most common cause of visual loss classified under retinal vascular disorders after diabetic retinopathy. So far, the number of patients suffering from retinal vein occlusion has increased, but the pathogenesis of retinal vein occlusion has not been fully understood and there are no treatments that are very long-lasting. The research of animal models on the pathogenesis and treatment of the RVO is very important. Therefore, this article gives a briefly review to the animals and model making methods used in retinal vein occlusion experiments, and discusses the advantages and disadvantages of various RVO animal models.

Abstract 111: Vein-Chip Is A New Experimental Model To Predict Pathophysiology Of SARS-CoV-2 Induced Thrombosis

There is a serious limitation of experimental models that can improve our limited knowledge of the mechanisms that regulate endotheliopathy and venous thrombosis (VT) clinically observed frequently amongst the most severe COVID-19 patients. Also, while observation and study of VT in humans are difficult due to the deep-lying nature of the deep veins in which VT develops, lab animal models do not include the venous valves, which are the sites for thrombus development in humans. We develop a Vein-chip microfluidic platform that includes venous valve architecture, endothelial cells (ECs), and whole blood flow, which can include the three factors of Virchow’s triad - endothelial inflammation, stasis of blood flow, and coagulable nature of blood. Our in silico and in vitro observations with Vein-Chip reveal that incompetent valves and thrombosis changes the blood flow pattern in and around the venous valves. We show that healthy endothelium at the venous valve cusps adapt to the complex flow patterns and have an anti-thrombotic phenotype compared to the venous lumen. But exposure of the lumen to living and replicating SARS-CoV-2 virus and inflammatory cytokines found in COVID-19 patient samples inflames the lumen and the valve endothelium becomes pro-thrombotic. Interestingly, when we directed our investigation to analyze the ACE2 expression on these cells, as ACE2 is the functional receptor of the SARS-CoV-2 virus, we found that ACE2 expression was poor under a static culture, but increased dramatically when venous ECs were exposed to shear stress within the vein-chip. This data supports our hypothesis that ACE2 expression (and therefore, SARS-CoV-2 entry into the endothelium) is dependent on venous hemodynamics and the Vein-Chip model is a highly dissectible platform that will help us to unravel the molecular mechanisms that lead to VT and its treatment strategies for COVID-19 and beyond.