Thrombus Volume Research Articles

Percutaneous pulmonary thrombectomy in hemodynamically unstable pediatric patient

An 11-year-old girl was referred to interventional radiology with a suspected pulmonary embolism (PE) 10 days post-resection of a benign craniopharyngioma. Acute massive PE was confirmed through computed tomography (CT) with extensive thrombus burden and CT evidence of high-grade right ventricular strain. Due to profound hypoxemia and hemodynamic instability, the patient was placed on extracorporeal membrane oxygenation and emergency percutaneous mechanical thrombectomy through the FlowTriever® System (Inari Medical, Irvine, CA) was pursued. A large volume of thrombus was extracted through aspiration without the need for thrombolytics. Postprocedure pulmonary angiography confirmed complete restoration of blood flow to both lungs and resolution of pulmonary symptoms continues 9 months after the procedure.

Low-density vulnerable thrombus/plaque volume on preoperative computed tomography predicts for spinal cord ischemia after endovascular repair for thoracic aortic aneurysm

BackgroundSimilar to open surgical repair, thoracic endovascular aortic repair (TEVAR) carries a risk of spinal cord ischemia (SCI). However, the generally lower incidence of SCI after TEVAR compared with that after open surgical repair, despite the inability to preserve the intercostal arteries, indicates different pathophysiologic mechanisms with the two procedures. We hypothesized that a microembolism from an aortic mural thrombus is the main cause of SCI. Thus, we evaluated the association between the density of a mural thrombus in the descending thoracic aorta and the development of SCI. MethodsA retrospective review of a prospectively assembled database was performed for all patients who had undergone surgery at a single institution from October 2008 to December 2018. Patient demographics and procedure-related variables were collected. The volume and Hounsfield unit (HU) value of mural thrombi in the whole descending thoracic aorta were estimated on preoperative computed tomography using a three-dimensional workstation. Logistic regression analysis was performed to identify the risk factors for SCI development. ResultsOf the 367 patients who had undergone TEVAR during the study period, 155 were excluded because of previous arch surgery (n = 59), previous descending thoracic aortic surgery (n = 6), previous TEVAR (n = 6), unavailability of optimal preoperative computed tomography data (n = 17), double-barreled dissection (n = 40), and other reasons. The mean ± standard deviation age of the remaining 212 patients was 75.8 ± 6.4 years, and 42 (19.8%) were women. Of the 212 patients, 14 (6.6%) developed SCI after TEVAR. The low mean density of the mural thrombus, total thrombus volume, low-density (≥−100 HU but <30 HU) thrombus volume, intermediate-density (≥30 HU but <150 HU) thrombus volume, treatment length, urgent surgery, and baseline dialysis differed significantly between patients with and without SCI. Although subsequent multivariate analysis could not be performed owing to the small number of SCI events, vulnerable low-density thrombus/plaque was a stronger predictor among the aneurysm-related factors of SCI after TEVAR on univariate analysis. Well-known risk factors, such as distal coverage between T8 and L1, left subclavian artery coverage, previous abdominal aortic surgery, and prophylactic spinal drainage, did not show significant differences. ConclusionsThe results from the present study have demonstrated that among aneurysm-related factors, a lower density mural thrombus/plaque in the descending thoracic aorta is a predictor of SCI development after TEVAR. These results suggest that microembolism is one of the important mechanisms of SCI after TEVAR, which might change the prophylactic strategy.

Bivalirudin vs. Heparin on Radial Artery Thrombosis during Transradial Coronary Intervention: An Optical Coherence Tomography Study.

Objectives This study aimed to evaluate the antithrombotic efficacy between bivalirudin and unfractionated heparin (UFH) on radial artery thrombosis (RAT) during transradial coronary intervention (TRI) by optical coherence tomography (OCT). Methods and Results We consecutively reviewed a total of 307 patients who underwent radial artery OCT inspection after TRI in our centre from October 2017 to January 2019; afterwards, 211 screened patients were divided into the UFH group (n = 144) and the bivalirudin group (n = 67) according to their anticoagulation strategy during TRI. The thrombosis in the radial artery was observed in 51 cases (24.17%) with a median thrombus volume of 0.054 mm3 (0.024, 0.334) and median thrombus score of 7 (4, 15). Thrombus occurred in 28 cases in the bivalirudin group with an incidence of 41.8%, which was significantly higher than that in the UFH group (n = 23, 16.0%, P < 0.001). This difference was even more remarkable after propensity score matching (bivalirudin group n = 22, 42.3% vs. UHF group n = 11, 13.9%, P < 0.001). Multivariate logistic analysis revealed that bivalirudin increased the RAT risk by 3.872 times (95% CI 2.006–8.354, P < 0.001) after adjustment for the other predictors. Conclusion In this present study, the use of bivalirudin was associated with a higher risk of RAT than UFH. It highlighted UFH should be a more considerable choice to prevent radial artery access thrombosis in TRI.

Correlation between Post-Procedure Residual Thrombus and Clinical Outcome in Deep Vein Thrombosis Patients Receiving Pharmacomechanical Thrombolysis in a Multicenter Randomized Trial

PurposeTo evaluate relationships between immediate venographic results and clinical outcomes of pharmacomechanical catheter-directed thrombolysis (PCDT). Materials and MethodsVenograms from 317 patients with acute proximal deep vein thrombosis (DVT) who received PCDT in a multicenter randomized trial were reviewed. Quantitative thrombus resolution was assessed by independent readers using a modified Marder scale. The physician operators recorded their visual assessments of thrombus regression and venous flow. These immediate post-procedure results were correlated with patient outcomes at 1, 12, and 24 months. ResultsPCDT produced substantial thrombus removal (P < .001 for pre-PCDT vs. post-PCDT thrombus scores in all segments). At procedure end, spontaneous venous flow was present in 99% of iliofemoral venous segments and in 89% of femoral–popliteal venous segments. For the overall proximal DVT population, and for the femoral–popliteal DVT subgroup, post-PCDT thrombus volume did not correlate with 1-month or 24-month outcomes. For the iliofemoral DVT subgroup, over 1 and 24 months, symptom severity scores were higher (worse), and venous disease-specific quality of life (QOL) scores were lower (worse) in patients with greater post-PCDT thrombus volume, with the difference reaching statistical significance for the 24-month Villalta post-thrombotic syndrome (PTS) severity score (P = .0098). Post-PCDT thrombus volume did not correlate with 12-month valvular reflux. ConclusionsPCDT successfully removes thrombus in acute proximal DVT. However, the residual thrombus burden at procedure end does not correlate with the occurrence of PTS during the subsequent 24 months. In iliofemoral DVT, lower residual thrombus burden correlates with reduced PTS severity and possibly also with improved venous QOL and fewer early symptoms.

Clinical Evaluation for the Role of High-Sensitivity C-Reactive Protein in Combination with D-Dimer and Wells Score Probability Test to Predict the Incidence of Deep Vein Thrombosis Among Cancer Patients.

BackgroundDeep vein thrombosis (DVT) is a frequent complication in cancer patients and is the second leading cause of death. The high level of C-reactive protein (CRP) is an acute phase reactant that induces tissue factor (TF) expression in monocytes, smooth muscle cells, and endothelial cells. The CRP level positively correlates with the incidence, extension, and volume of thrombus. TF expression triggers the coagulation system including the formation of thrombin and circulating fibrin such as prothrombin fragment 1+2 (F1 + 2) and D-dimer.ObjectiveTo determine the diagnostic value of high-sensitivity (hs)-CRP, D-dimer, and Wells score combination to predict the incidence of DVT on clinically suspected DVT (Wells score ≥2) cancer patients.Subjects and MethodsThis study was a cross-sectional study on a diagnostic test to determine the diagnostic value of hs-CRP and D-dimer for early detection of DVT on clinically suspected DVT (Wells score ≥2) cancer patients. It was conducted in Dr. Kariadi Hospital, Semarang Indonesia on 35 subjects. The diagnosis of DVT was confirmed by color duplex sonography. The diagnostic accuracy of combination of hs-CRP, D-dimer, and Wells score was analyzed by logistic regression.ResultsDVT was confirmed in 10 subjects (28,6%). The cut-off point of hs-CRP levels for probable DVT was ≥51.05 mg/L and for D-dimer was ≥5030 µg/L. The median levels of both variables were higher in the subjects with DVT compared with the subjects without DVT, but it was not statistically significant. The combination of hs-CRP (≥51.05 mg/L), D-dimer (≥5030 µg/L), and Wells score ≥3 had the high accuracy (94.1%) to predict the incidence of DVT compared with hs-CRP (65.0%), D-dimer (54.7%), and combination of hs-CRP and D-dimer (71.0%).ConclusionThe combination of hs-CRP (≥51.05 mg/L), D-dimer (≥5030 µg/L), and Wells score ≥3 can predict the incidence of DVT in cancer.

Anticoagulation Using Rivaroxaban for VTE Treatment: Dose Adjustment According to Thrombus Volume

Anticoagulation Using Rivaroxaban for VTE Treatment: Dose Adjustment According to Thrombus Volume

Gender differences of morphological and hemodynamic characteristics of abdominal aortic aneurysm

BackgroundGender difference in cardiovascular diseases (CVDs) is an important topic in the field of cardiovascular medicine. In this study, we focused on the mortality difference of abdominal aortic aneurysms (AAA), which is higher for female than that of male. The aim of this study was to verify whether morphological and hemodynamic factors play their roles in this phenomenon.MethodsPatient-specific AAA models of 11 females and 23 males with similar age and body mass index (BMI) have been reconstructed based on clinical computed tomography (CT) data. Firstly, the morphological parameters (diameters, curvature, intraluminal thrombus volume, etc.) of AAA models and lumbar vertebrae models were collected and analyzed. Then, based on statistical results of morphological parameters, uniformed male and female AAA models were reconstructed, and hemodynamic simulations were conducted respectively. In post-processing, the hemodynamic performances induced by gender-different morphological geometries were analyzed and compared.ResultsThe comparison of morphological parameters revealed that the average curvature of lumbar vertebrae and AAA centerline of female AAA models were obviously higher than that of the male. The amount of intraluminal thrombus in female AAA models was relatively lower than that of the male. According to the hemodynamic simulation, the uniform female AAA model has higher peak pressure, lower oscillatory shear stress index (OSI), and lower relative residence time (RRT) than that of the male model, all of which put female AAA to a relatively higher risk hemodynamic situation.ConclusionsThe morphological and hemodynamic features of AAA have very obvious gender differences that would induce higher risk of rupture for female AAA biomechanically. These findings would help to explore the mechanism of gender differences in AAA and draw attention to gender-specific consideration for AAA treatment. More morphological and hemodynamic indictors are suggested to be involved in the future guidelines.

Further evidence on the relationship between abdominal aortic aneurysm and periodontitis: A cross-sectional study.

Periodontitis is a chronic inflammatory disease characterized by Gram-negative bacteria responsible for the degradation of tissues surrounding tooth. Moreover, periopathogens can invade the bloodstream, disseminate and promote cardiovascular disease, such as the link between Porphyromonas gingivalis and atherosclerosis. The aim of this study was to explore the relationship between the severity of periodontitis and of abdominal aortic aneurysm (AAA). This cross-sectional study compared patients with stable AAA (n = 30) and patients with unstable AAA (n = 31) based on aortic diameter, growth rate, and eligibility for surgical intervention. Periodontal clinical parameters were recorded as well as the Periodontal Inflamed Surface Area and the Periodontal Index for Risk of Infectiousness (PIRI). Microbiological analyses were performed on saliva and supragingival and subgingival plaque. Quantification of Tannerella forsythia (Tf), Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), and Prevotella intermedia (Pi) was done by quantitative polymerase chain reaction. The two AAA groups were homogeneous for age, sex, and most risk factors except hypertension and chronic obstructive pulmonary disease. Periodontal parameters were comparable but the proportion of patients with high PIRI scores was greater in those with unstable AAA (51.6% versus 23.3%). The probing depth (PD) and the proportion of PD >6 mm were positively correlated with AAA size and thrombus volume. Several associations were found between periopathogens such as Pg and AAA diameters and volumes, but no difference could be evidenced between stable and unstable AAA groups. Periodontitis was highly prevalent in both stable and unstable AAA patients. Severe and progressive periodontitis (stage IV and grade C) tended to be more frequent in the group of patients with unstable AAA. Moreover, Pg was observed in all the samples (saliva, supragingival, and subgingival plaque) and was correlated with AAA diameters and volumes. The study evidenced potential relationships between periodontitis severity and size of AAA.

Feasibility and accuracy of a novel automated three-dimensional ultrasonographic analysis system for abdominal aortic aneurysm: comparison with two-dimensional ultrasonography and computed tomography

BackgroundAccurate measurement of the maximum aortic diameter (Dmax) is crucial for patients with abdominal aortic aneurysm (AAA). Aortic computed tomography (CT) provides accurate Dmax values by three-dimensional (3-D) reconstruction but may cause nephrotoxicity because of contrast use and radiation hazard. We aimed to evaluate the accuracy of a novel semi-automated 3-D ultrasonography (3-D US) system compared with that of CT as a reference.MethodsPatients with AAA (n = 59) or individuals with normal aorta (n = 18) were prospectively recruited in an outpatient setting. Two-dimensional ultrasonography (2-D US) and 3-D US images were acquired with a single-sweep volumetric transducer. The analysis was performed offline with a software. Dmax and the vessel area of the Dmax slice were measured with 2-D US, 3-D US, and CT. The lumen and thrombus areas of the Dmax slice were also measured in 40 patients with intraluminal thrombus. Vessel and thrombus volumes were measured using 3-D US and CT.ResultsThe Dmax values from 3-D US demonstrated better agreement (R2 = 0.984) with the CT values than with the 2-D US values (R2 = 0.938). Overall, 2-D US underestimated Dmax compared with 3-D US (32.3 ± 12.1 mm vs. 35.1 ± 12.0 mm). The Bland-Altman analysis of the 3-D US values, revealed better agreement with the CT values (2 standard deviations [SD], 2.9 mm) than with the 2-D US values (2 SD, 5.4 mm). The vessel, lumen, and thrombus areas all demonstrated better agreement with CT than with 2-D US (R2 = 0.986 vs. 0.960 for the vessel, R2 = 0.891 vs. 0.837 for the lumen, and R2 = 0.977 vs. 0.872 for the thrombus). The thrombus volume assessed with 3-D US showed good correlation with the CT value (R2 = 0.981 and 2 SD in the Bland-Altman analysis: 13.6 cm3).ConclusionsOur novel semi-automated 3-D US analysis system provides more accurate Dmax values than 2-D US and provides precise volumetric data, which were not evaluable with 2-D US. The application of the semi-automated 3-D US analysis system in abdominal aorta assessment is easy and accurate.

Changes in Neck Angle, Neck Length, Maximum Diameter, Maximum Area and Thrombus after Endovascular Aneurysm Repair.

PurposeThe correlation of initial anatomy of the aneurysm, aneurysmal remodeling and endoleaks is controversial. We performed a retrospective study to measure aneurysmal remodeling with time, and to assess the structural changes in the aneurysm neck after endovascular aneurysm repair (EVAR).Materials and MethodsFrom January 2013 to February 2018, 108 patients with abdominal aortic aneurysms (AAA) underwent EVAR. Follow-up computed tomography images were available for 90 patients. Anatomic variables, including the neck angle, neck length, maximal diameter, maximal area, and thrombus volume were measured. Temporal changes were measured preoperatively, immediate postoperatively (within 1 week after EVAR), and at 6 months, 1 year, and 2 years post-EVAR. Correlation between the variables according to the temporal changes and presence of type Ia endoleaks (T1aE) was analyzed.ResultsThe mean follow-up period was 10.63±20.34 months. Significant decreases in neck angle and length occurred immediately postoperative (P<0.001 and 0.036). Maximum diameter decreased at 6 months post-EVAR (P=0.003), but no significant changes in the maximal area occurred over time (P=0.142). Thrombus volume in the aneurysm sac increased immediately post-EVAR (P=0.008). There was no significant relationship between T1aE and neck changes in the group and time comparison (P=0.815 and 0.970).ConclusionChanges in neck angle, length and thrombus volume occurred immediately after EVAR, whereas a change in the maximum diameter of the AAA was noted 6 months after EVAR. Preoperative anatomic variables related with T1aE were not found.

Quantitative Volumetric Comparison of Direct Oral Anticoagulant and Vitamin K Antagonist Treatment for Pulmonary Thrombus Reduction During the Acute Phase in Symptomatic Patients

Recent clinical trials' findings have revealed the therapeutic noninferiority of direct oral anticoagulant (DOAC) to standard therapy with vitamin K antagonist (VKA) in patients with pulmonary thromboembolism (PTE). However, few studies have quantitatively analyzed thrombus reduction in the pulmonary artery. This observational study included 38 symptomatic PTE patients with stable hemodynamics. All patients received an intravenous heparin bolus followed by continual heparin injections immediately after the PTE diagnosis. The heparin was discontinued after edoxaban therapy began in the DOAC group (n=22) or after the therapeutic range for the prothrombin time-international normalized ratio was achieved in the VKA group (n=16). The thrombus volumes in the pulmonary arteries were quantitatively analyzed using contrast-enhanced computed tomography scans, and they were compared at baseline and at 2 weeks after admission. The pulmonary thrombus volumes declined in the VKA and DOAC groups from 7.9 to 4.2 cm3 (P=0.048) and from 7.1 to 3.7 cm3 (P < 0.01), respectively, and the thrombus reduction rates did not differ significantly between the groups (-34% vs. -64%, respectively; P=0.38). The fibrinogenolysis parameter changes during the14 days after admission were similar in both groups. Compared with the VKAgroup, the average hospital stay was 9days shorter in the DOAC group. There were no in-hospital deaths, and 1 case experienced major bleeding in the VKA group. In relation to pulmonary artery thrombus volume reduction, DOAC monotherapy for PTE may be comparable with standard therapy involving VKAs.

Influence of Patient-Specific Characteristics on Transcatheter Heart Valve Neo-Sinus Flow: An In Silico Study.

Thrombosis in post-transcatheter aortic valve replacement (TAVR) patients has been correlated with flow stasis in the neo-sinus. This study investigated the effect of the post-TAVR geometry on flow stasis. Computed tomography angiography of 155 patients who underwent TAVR using a SAPIEN 3 were used to identify patients with and without thrombosis, and quantify thrombus volumes. Six patients with 23-mm SAPIEN 3 valves were then selected from the cohort and used to create patient-specific post-TAVR computational fluid dynamic models. Regions of flow stasis (%Volstasis, velocities below 0.05m/s) were identified. The results showed that all post-TAVR anatomical measurements were significantly different in patients with and without thrombus, but only sinus diameter had a linear correlation with thrombus volume (r = 0.471, p = 0.008). A linear correlation was observed between %Volstasis and thrombus volume (r = 0.821, p = 0.007). The combination of anatomy and valve deployment created a unique geometry in each patient, which when combined with patient-specific cardiac output, resulted in distinct flow patterns. While parametric studies have shown individual anatomical or deployment metrics may relate to flow stasis, the combined effects of these metrics potentially contributes to the biomechanical environment promoting thrombosis, therefore hemodynamic studies of TAVR should account for these patient-specific factors.

Reducing state attenuates ectodomain shedding of GPVI while restoring adhesion capacities of stored platelets: evidence addressing the controversy around the effects of redox condition on thrombosis.

Thrombosis involves different stages including platelet adhesion to the site of injury, aggregatory events governed by integrin activation, pro-inflammatory responses recruiting leukocytes and finally, pro-coagulant activity which results in fibrin generation and clot formation. As important signaling agents, reactive oxygen species (ROS) reduce thrombus volume and growth, however given such a multistage mechanism, it is not well-elucidated how ROS inhibition modulates thrombosis. PRP-platelet concentrates (PCs) were either treated with ROS-reducing agents (1mM NAC or 30μM NOX inhibitor, VAS2870) or kept untreated during storage. Shedding and expression of platelet adhesion receptors in presence of inhibitors, agonists and CCCP (as controls) were analyzed by flow cytometery and western blot respectively. Besides above parameters, platelet adhesion to collagen in stored platelets was examined in presence of ROS inhibitors using fluorescence-microscopy. Highest levels of adhesion receptors shedding were achieved by ionophore and CCCP while collagen induces much more GPVI shedding than that of GPIbα. ROS inhibition reduced receptors shedding from day 3 of storage while enhanced their expressions. ROS inhibition not only did not reduce platelet adhesion capacity but it also enhanced platelets adhesion (in presence of NAC) or spreading (in presence of VAS2870) in 5days-stored PCs. While reducing state significantly inhibits platelet aggregation and thrombus growth, our results indicated that as a first stage of thrombosis, platelet adhesion is resistance to such inhibitory effects. These findings highlight the fact that integrin-dependent platelet activation is much more vulnerable to the inhibition of ROS generation than GPVI-dependent platelet adhesion. Presumably, inhibition of platelet activating signals by ROS inhibitors preserves platelet adhesiveness to collagen due to lessening GPVI shedding.

Post-implantation syndrome: the impact of different devices for endovascular abdominal aortic aneurysm repair and related etiopathogenetic implications.

Postimplantation syndrome (PIS) is a systemic inflammatory response occurring in early phase after abdominal aortic aneurysm (AAA) endovascular repair (EVAR). PIS can also occur after endovascular aneurysm sealing (EVAS) with Nellix system which prevent new onset of mural thrombus inside. Aim was to compare the incidence of PIS after EVAS and EVAR to evaluate the possible role of the new-onset thrombus inside the aneurysmal sac. Secondary aims were to assess the effect of AFX (Endologix) endoskeleton compared with other commercially available exoskeleton PTFE stent grafts on inflammatory response and its relationship with the clinical outcomes. From 2013 to 2017, data on 60 elective EVAS with Nellix system (Endologix, Irvine, CA, USA) and 110 EVAR with ePTFE devices (56 AFX devices and 54 other stent grafts) for AAA patients were retrospectively collected. PIS was defined as composite of body temperature ≥38 °C coinciding with leukocyte count >12,000/mL and hs-CPR >10 mg/L. New-onset thrombus volume after EVAR was calculated by: endograft volume - preoperative luminal volume=volume of new-onset thrombus, whereas post-EVAS thrombus volume was calculated from difference between AAA volume and volume of Nellix endobags, including balloon expandable stents. Nonparametric χ2 distribution with corresponding P values were used to assess differences among categorical variables with regard to endograft type. Threshold of statistical significance was P<0.05. Subgroup analysis of outcomes by stent-graft design was performed using independent-samples t-test. EVAS with Nellix system was associated with lower incidence of PIS compared to EVAR using both AFX device and other endografts (8.3%, 30%, 35%, respectively, P=0.001). No significant new-onset of mural thrombus occurred following EVAS while an avarage new-onset thrombus of 21% and 14% was found in EVAR group A and group B, respectively. No statistically significant difference of PIS incidence was observed after endoskeleton AFX device deployment compared with other EVAR exoskeleton endografts. During follow-up, major complications were proportionally but not significantly (P=0.43) less frequent after EVAS (10.3%) than after EVAR and after EVAR using AFX device (8.9%) than after EVAR with other PTFE stent grafts (16.4%). The etiology and pathophysiology of PIS is not yet well understood. It is speculated that the type of the stent graft or the mural thrombus within the AAA may play a role in determing this inflammatory response. In this study, PIS was significantly less frequent after EVAS than EVAR. The lower inflammatory reaction observed after EVAS might be related to the endobags of Nellix system which completely seal the aneurysm sac reducing the new onset of mural thrombus. This could confirm the role of new-onset mural thrombus in the genesis of PIS. The systemic inflammatory response does not significantly differ after endoskeleton AFX device deployment compared with other EVAR exoskeleton stent grafts. PIS does not seem to have any significant prognostic implications in terms of major adverse events.

Location of Reentry Tears Affects False Lumen Thrombosis in Aortic Dissection Following TEVAR

Purpose: To report a study that assesses the influence of the distance between the distal end of a thoracic stent-graft and the first reentry tear (SG-FRT) on the progression of false lumen (FL) thrombosis in patients who underwent thoracic endovascular aortic repair (TEVAR). Materials and Methods: Three patient-specific geometrical models were reconstructed from postoperative computed tomography scans. Two additional models were created by artificially changing the SG-FRT distance in patients 1 and 2. In all 5 models, computational fluid dynamics simulations coupled with thrombus formation modeling were performed at physiological flow conditions. Predicted FL thrombosis was compared to follow-up scans. Results: There was reduced false lumen flow and low time-averaged wall shear stress (TAWSS) in patients with large SG-FRT distances. Predicted thrombus formation and growth were consistent with follow-up scans for all patients. Reducing the SG-FRT distance by 30 mm in patient 1 increased the flow and time-averaged wall shear stress in the upper abdominal FL, reducing the thrombus volume by 9.6%. Increasing the SG-FRT distance in patient 2 resulted in faster thoracic thrombosis and increased total thrombus volume. Conclusion: The location of reentry tears can influence the progression of FL thrombosis following TEVAR. The more distal the reentry tear in the aorta the more likely it is that FL thrombosis will occur. Hence, the distal landing zone of the stent-graft should be chosen carefully to ensure a sufficient SG-FRT distance.

Quantifying Physical Thrombus Characteristics on Cardiovascular Biomaterials Using MicroCT.

Hemocompatibility is a critical consideration when designing cardiovascular devices. Methods of assessing hemocompatibility range from in vitro protein adsorption and static platelet attachment to in vivo implantation. A standard preclinical assessment of biomaterial hemocompatibility is ex vivo quantification of thrombosis in a chronic arteriovenous shunt. This technique utilizes flowing blood and quantifies platelet accumulation and fibrin deposition. However, the physical parameters of the thrombus have remained unknown. This study presents the development of a novel method to quantify the 3D physical properties of the thrombus on different biomaterials: expanded polytetrafluoroethylene and a preclinical hydrogel, poly(vinyl alcohol). Tubes of 4–5 mm inner diameter were exposed to non-anticoagulated blood flow for 1 hour and fixed. Due to differences in biomaterial water absorption properties, unique methods, requiring either the thrombus or the lumen to be radiopaque, were developed to quantify average thrombus volume within a graft. The samples were imaged using X-ray microcomputed tomography (microCT). The methodologies were strongly and significantly correlated to caliper-measured graft dimensions (R2 = 0.994, p < 0.0001). The physical characteristics of the thrombi were well correlated to platelet and fibrin deposition. MicroCT scanning and advanced image analyses were successfully applied to quantitatively measure 3D physical parameters of thrombi on cardiovascular biomaterials under flow.

Combining Volumetric and Wall Shear Stress Analysis from CT to Assess Risk of Abdominal Aortic Aneurysm Progression.

Background Despite known limitations, the decision to operate on abdominal aortic aneurysm (AAA) is primarily on the basis of measurement of maximal aneurysm diameter. Purpose To identify volumetric and computational fluid dynamics parameters to predict AAAs that are likely to progress in size. Materials and Methods This study, part of a multicenter prospective registry (NCT01599533), included 126 patients with AAA. Patients were sorted into stable (≤10-mL increase in aneurysm volume) and progression (>10-mL increase in aneurysm volume) groups. Initial AAA characteristics of the derivation cohort were analyzed (maximal diameter and surface, thrombus and lumen volumes, maximal wall pressure, and wall shear stress [WSS]) to identify relevant parameters for a logistic regression model. Model and maximal diameter diagnostic performances were assessed in both cohorts and for AAAs smaller than 50 mm by using area under the receiver operating characteristic curve (AUC). Results Eighty-one patients were included (mean age, 73 years ± 7 years [standard deviation]; 78 men). The derivation and validation cohorts included, respectively, 50 and 31 participants. In the derivation cohort, there was higher mean lumen volume and lower mean WSS in the progression group compared with the stable group (60 mL ± 14 vs 46 mL ± 18 [P = .005] and 66% ± 6 vs 53% ± 9 [P = .02], respectively). Mean lumen volume and mean WSS at baseline were correlated to total volume growth (r = 0.47 [P = .002] and -0.42 [P = .006], respectively). In the derivation cohort, a regression model including lumen volume and WSS to predict aneurysm enlargement was superior to maximal diameter alone (AUC, 0.78 vs 0.52, respectively; P = .003); although no difference was found in the validation cohort (AUC, 0.79 vs 0.71, respectively; P = .51). For AAAs smaller than 50 mm, a regression model that included both baseline WSS and lumen volume performed better than maximal diameter (AUC, 0.79 vs 0.53, respectively; P = .01). Conclusion Combined analysis of lumen volume and wall shear stress was associated with enlargement of abdominal aortic aneurysms at 1 year, particularly in aneurysms smaller than 50 mm in diameter. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Mitsouras and Leach in this issue.

Removal of tumor thrombus from the azygos vein in an esophageal squamous cell carcinoma patient

BackgroundEsophageal squamous cell carcinoma with tumor thrombus in the arch of the azygos vein has not been reported to date. Neoadjuvant chemotherapy can decrease the stage in patients with advanced preoperative tumor staging, regaining surgical opportunities and significantly prolonging progression-free survival and overall survival. Herein, we present a case of esophageal squamous cell carcinoma accompanied by tumor thrombus in the arch of the azygos vein, and the patient underwent radical surgery after neoadjuvant chemotherapy.Case presentationA 63-year-old male with esophageal squamous cell carcinoma was found to have tumor thrombus formation in the arch of the azygos vein. Four courses of neoadjuvant chemotherapy with the TP regimen (paclitaxel plus nedaplatin) were given. Reexamination revealed a significant reduction in tumor and tumor thrombus volume. Therefore, McKeown radical resection for esophageal cancer and removal of the tumor thrombus in the arch of the azygos vein were performed. Postoperative pathology suggested complete remission of the esophageal tumor and the presence of small focal cancer tissues in the arch of the azygos vein.ConclusionWe report a case of esophageal squamous cell carcinoma with tumor thrombus formation in the azygos vein. We conducted radical resection after 4 rounds of neoadjuvant chemotherapy, and the pathological results revealed complete remission of the tumor. We report our experience addressing this rare case, and we hope to find the underlying mechanism of tumor thrombus formation and whether it has any effects on prognosis in our future study.

A Comparative Study of Biomechanical and Geometrical Attributes of Abdominal Aortic Aneurysms in the Asian and Caucasian Populations.

In this work, we provide a quantitative assessment of the biomechanical and geometric features that characterize abdominal aortic aneurysm (AAA) models generated from 19 Asian and 19 Caucasian diameter-matched AAA patients. 3D patient-specific finite element models were generated and used to compute peak wall stress (PWS), 99th percentile wall stress (99th WS), and spatially averaged wall stress (AWS) for each AAA. In addition, 51 global geometric indices were calculated, which quantify the wall thickness, shape, and curvature of each AAA. The indices were correlated with 99th WS (the only biomechanical metric that exhibited significant association with geometric indices) using Spearman's correlation and subsequently with multivariate linear regression using backward elimination. For the Asian AAA group, 99th WS was highly correlated (R2 = 0.77) with three geometric indices, namely tortuosity, intraluminal thrombus volume, and area-averaged Gaussian curvature. Similarly, 99th WS in the Caucasian AAA group was highly correlated (R2 = 0.87) with six geometric indices, namely maximum AAA diameter, distal neck diameter, diameter-height ratio, minimum wall thickness variance, mode of the wall thickness variance, and area-averaged Gaussian curvature. Significant differences were found between the two groups for ten geometric indices; however, no differences were found for any of their respective biomechanical attributes. Assuming maximum AAA diameter as the most predictive metric for wall stress was found to be imprecise: 24% and 28% accuracy for the Asian and Caucasian groups, respectively. This investigation reveals that geometric indices other than maximum AAA diameter can serve as predictors of wall stress, and potentially for assessment of aneurysm rupture risk, in the Asian and Caucasian AAA populations.

Effects of Long-term Thrombin Inhibition (Dabigatran Etexilate) on Spontaneous Thrombolytic Activity during the Progression of Atherosclerosis in ApoE-/--LDLR-/- Double-Knockout Mice.

Background and ObjectivesAtherosclerosis is characterized by a hypercoagulable state, during which coagulation and fibrinolytic factors are activated simultaneously. However, details regarding the thrombolytic pathway in this context remain unknown. Here we investigated how direct long-term inhibition of thrombin influenced spontaneous thrombolytic activity during atherosclerotic progression in apolipoprotein E (ApoE)–/––low density lipoprotein receptor (LDLR)–/– double-knockout mice.MethodsAll mice received either standard chow (placebo group) or dabigatran-containing chow for 22 weeks, after which we evaluated them. The amount of atherosclerosis was estimated as the ratio of the atherosclerotic area to the total aortic intimal area. In addition, we used immunohistochemistry to analyze the expression of tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), thrombin activatable fibrinolysis inhibitor (TAFI), and endothelial nitric oxide synthase (eNOS) in atherosclerotic regions. To evaluate thrombolysis, we used a He–Ne laser to induce thrombosis in vessels of the cremaster muscle and then measured the thrombus volume over time.ResultsThe atherosclerotic area was smaller and thrombolytic activity greater in the dabigatran-treated group than in the placebo group. Furthermore, according to the thrombolysis model, spontaneous thrombolytic activity was increased in the dabigatran-treated mice compared with the placebo mice. In support of these results, immunohistochemistry demonstrated decreased expression of PAI-1 and TAFI but increased expression of eNOS in the dabigatran group compared with the placebo group. However, t-PA expression did not differ between groups.ConclusionsDirect long-term inhibition by dabigatran etexilate of thrombin led to an increase in spontaneous thrombolytic activity decreasing the expression of PAI-1 and TAFI.