Transonic Systems Research Articles

Intraoperative Transit-Time Flow as a Predictor of Failure after Infrainguinal Revascularization with Heparin-Bonded Expanded Polytetrafluoroethylene Graft

The heparin-bonded expanded polytetrafluoroethylene (He-ePTFE) conduit is an option for patients requiring infrainguinal revascularization (iIR), but the risk of failure may be unpredictable, especially in cases with poor run-off. Intraoperative transit-time flow (TTF) provides an automated and quantitative analysis of flow and may serve as an adjunct evaluation during surgical revascularization. The aim of this study was to assess TTF in patients undergoing iIR with He-PTFE at 3 referral hospitals and to establish a predictive flow threshold for graft occlusion. A prospective registry initiated in 2020 enrolled patients undergoing iIR using He-PTFE for critical limb ischemia or severe claudication, and TTF measurement was analyzed. Preoperative assessments of anatomical and clinical characteristics were available for all patients. The HT353 Optima Meter (Transonic Systems Inc., Ithaca, NY, USA) was used in all procedures according to a standardized protocol. The institutional ethics committee approved the study. A predictive model using receiver operating characteristic curve analysis was utilized to establish the threshold of flow, and variables were compared. Anatomical and clinical evaluation were reported according to Rutherford grade, Global Limb Anatomic System and Wound, Ischemia, and foot Infection classification. The main outcome considered was the correlation between TTF and graft occlusion. Secondary outcomes included survival, other predictors of graft occlusion, freedom from major adverse cardiovascular events, and freedom from major amputation. Among 68 patients, 55.8% had Rutherford 5-6, 45.6% had Global Limb Anatomic System 3 and 73.5% had Wound, Ischemia, and foot Infection 3-4. Distal anastomosis was at tibial level in 23.5% and mean diameter of conduit was 6.4mm. Basal and postoperative TTF were 27.8±15.6ml/min and 109.0±53.0 ml/min, respectively. After a mean follow-up of 18±13months, 7 (10.9%) patients presented graft occlusion and 5 (7.8%) required major amputation. TTF threshold=80ml/min revealed a sensitivity and specificity of 81.8% (95% confidence interval 48.2-97.7) and 80.7% (95% confidence interval 68.1-90.0) respectively, and it was selected as cut-off for graft occlusion. Freedom from graft occlusion in patients with TTF >80ml/min vs. TTF ≤80ml/min at 6, 12, and 24months was 95.7% (standard error (SE)=0.030) vs. 65.5% (SE=0.115), 95.7% (SE=0.030) vs. 58.9% (SE=0.120) and 90.9% (SE=0.054) vs. 51.6% (SE=0.126), P=0.0003. No statistical difference in primary patency, secondary patency and limb salvage was observed. At multivariate analysis, distal anastomosis at tibial vessel (odds ratio 8.50) and TTF ≤80ml/min (odds ratio 9.39) were independent predictors of graft occlusion. These results suggest that TTF may serve as a valuable tool in the management of iIR. A TTF measurement of ≤80ml/min should be regarded as a predictor of graft occlusion, prompting consideration of additional intraoperative maneuvers to enhance arterial flow. Caution should be exercised in patients requiring direct tibial artery revascularization, as it represents a predictor of failure independent of TTF levels. Larger cohorts of patients and longer follow-up periods are necessary to confirm these findings.

Functional state of the endothelium in men after mine-explosive injury during the war in Ukraine

Mine-explosive trauma (MET) is the most common trauma type and one of the main disability causes of the able-bodied contingent. Among the mechanisms of the cardiovascular and cerebrovascular disorders development after MET, endothelial dysfunction (ED) plays an important role. The study aims - to assess the functional state of the microvessels and large arteries endothelium in men after a mine-explosive injury. Materials and methods: the functional state of the skin microvessels endothelium was determined using a two-channel laser Doppler flowmeter BLF-21D "Transonic Systems Inc" (USA) during the test with the creation of reactive hyperemia. The function of the large arteries endothelium was determined using the D.S. Celermajer test, with post-occlusion reactive hyperemia according to the generally accepted method on the Nemio XG device, SSA-580A (Toshiba) with a high-frequency linear sensor with a central frequency of 7 MHz. We examined men with mild MET (average age 37.7 ± 1.5 years). The control group was represented by 43 practically healthy men without MET (average age 41.8 ± 2.1 years). Results: dysfunction of the microvessels endothelium was found in most persons with MET (69.1%), compared to men without MET (41.9%). Dysfunction of the large vessels endothelium was found in 40.4% of examined persons with MET. Persons with MET have a combination of large and small vessel endothelial dysfunction in 23.4% of cases, at the same time persons without MET have a higher proportion of isolated microvessel endothelial dysfunction (34.9%). Conclusions: men with MET often have arterial endothelial dysfunction with microvascular endothelial dysfunction together, whereas men without MET have predominantly isolated microvascular endothelial dysfunction. ________________________________________________________________________________________ Keywords: mine-explosive injury; functional state of the endothelium; microcirculation.

Beat-by-beat volume calibration refines pressure-volume derived indices of left ventricular function in the rat

Objective: Cardiac pressure-volume studies have advanced much of our understanding of mammalian cardiovascular physiology. Using admittance or conductance technology, the advantage of this technology over other methods to assess cardiovascular function is the ability to derive beat-by-beat pressure-volume loops and generate estimations of myocardial work (stroke work), as well as load-independent systolic (i.e., contractility) and diastolic (i.e., compliance) function from a caval occlusion. While these catheters are capable of extremely accurate recordings of cardiac pressure, volume measurement relies on a series of calibration steps that are oft-performed in isolation or at discrete timepoints. We propose a novel method that enables the refinement of ventricular volume measurement by enabling a beat-by-beat calibration of stroke volume (SV) at baseline and, most importantly, during caval occlusion where both the shape and characteristics of the ventricle are dynamically changing. Hypothesis: We hypothesised that beat-by-beat calibration of SV has a significant effect on PV-catheter derived indices of left ventricle (LV) function. Methodology: Data were collected from 10 rodents that were intubated, ventilated, and urethane anesthetized. We placed an admittance pressure-volume catheter (1.6F Scisense, Transonic Systems, Inc.) into the LV via an apical approach following thoracotomy, a perivascular flow probe (Transonic Systems, Inc.) was placed around the ascending aorta, a blood pressure catheter in the iliac artery, femoral venous lines for fluid/drug infusions, and an arterial line for blood gas analysis. We then assessed baseline and load-independent systolic function using the admittance catheter with and without beat-by-beat volume corrections obtained by integration of the perivascular flow data. Results: Firstly, we confirmed that the standard metrics of load-independent systolic function were increased in response to dobutamine (β1 agonist) and reduced in response to esmolol (β1 blocker). We then found that beat-by-beat volume correction from the perivascular flow probe increased baseline measures of SV and stroke work (SW). Comparing indices of load-independent systolic function calculated from corrected vs. uncorrected values of SV and SW, we found that beat-by-beat volume correction resulted in no significant change in d P/dt max - V ed (P=0.339) but a significant increase in PRSW (from 116±18 to 129±20 mmHg, P=0.020). Conclusions: Standard approaches to PV studies are able to accurately discern changes in contractile state. However, beat-by-beat calibration of the volume signal improves the absolute determination of volume indices and therefore influences derived measures of contractility. This research was funded by an NSERC Alliance grant to CRW and Mitacs Accelerate Postdoctoral Fellowship to OHW. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Impact of Intraoperative Graft Blood Flow Measurement on Early Graft Function

The aim of this study is to evaluate the impact of intraoperative allograft vascular flow on early kidney graft function. A total of 159 patients underwent kidney transplantation from January 2017 to March 2022 at Linkou Chang Gung Memorial Hospital. Graft arterial and venous blood flow was measured separately with a transient time flowmeter (Transonic HT353; Transonic Systems, Inc, Ithaca, NY, United States) after ureteroneocystostomy. The early outcomes, including the postoperative creatinine level, were analyzed accordingly. There were 83 males and 76 females, with a mean age of 44.5 years. The mean graft arterial flow measured was 480.6 mL/min, and the mean venous flow was 506.2 mL/min. Delayed graft function (DGF) incidence was 36.5%, 32.5%, and 40.8% in total, living, and deceased donor groups, respectively. Living donor and deceased donor kidney transplantation were analyzed separately. In the DGF subgroup, there were lower graft venous flows, higher body mass index (BMI), and more male patients in the living kidney transplant group. Similarly, the deceased donor kidney transplantation group with delayed graft function tended to have higher body height, higher body weight, higher BMI, and more diabetes mellitus. The multivariate analysis showed that lower graft venous blood flow (odds ratio [OR]=0.995, P=.008) and higher BMI (OR=1.144, P=.042) were significantly correlated with delayed graft function in living donor kidney transplantations. In the deceased donor group, a multivariate analysis of risk factors showed that BMI had a significant correlation with delayed graft function (OR=1.41, P=.039). Graft venous blood flow was significantly associated with delayed graft function in living donor kidney transplantation, and high BMI was correlated with DGF in all patients receiving kidney transplantation.

Parametric modeling and analysis of transonic aeroelastic systems based on incremental learning

The aerodynamic reduced order model (ROM) is an effective tool for predicting unsteady aerodynamics and aeroelastic responses with high accuracy and low computational costs. However, traditional aerodynamic ROMs with respect to different flow conditions are lack of robustness. How to enhance dramatically the generalization capability of aerodynamic ROMs should be further studied. This paper presents three parametric ROMs based on the least squares support vector regression algorithm (LS-SVR) and two incremental learning algorithms. LS-SVR is used to establish the relationship between aerodynamic inputs and outputs based on training data from high-fidelity flow simulations. And the Mach number is considered as an additional system input to account for varying flow conditions. The main contribution of incremental learning algorithms based on LS-SVR is that it does not need to reconstruct the ROM when adding sample data. For incremental learning algorithm with forgetting mechanism, training samples are added in the manner of a time-window to improve training efficiency. To illustrate the performance of these ROMs, the aerodynamic and aeroelastic responses of a NACA 0012 airfoil with two degrees of freedom are investigated. The simulation results show that both unsteady aerodynamic results and aeroelastic responses computed by using the three ROM-based models agree well with the results of the high-fidelity simulation. The three proposed ROMs have better generalization capacity and modeling efficiency.

Enhanced nonlinear state–space identification for efficient transonic aeroelastic predictions

Transonic aerodynamic systems exhibit strong nonlinearities due to various factors such as flow separations and shock wave oscillations. Thus, transonic aerodynamic modeling methods based on system identifications have attracted increasing attention. However, the dimensions of the models constructed via the current system identification methods are so high that it is difficult to predict transonic flutters and limit cycle oscillations simultaneously. This paper proposes an enhanced nonlinear state–space modeling method to identify a two-dimensional aerodynamic system in the transonic region. At first, the parsimonious linear model with modified inputs is identified by using the eigensystem realization algorithm. The model order is reduced by substituting the generalized displacement of the first-order mode (dominated by plunge) with its generalized velocity in the inputs. The polynomial functions are then used to represent the nonlinearities in the transonic aerodynamic systems. The polynomial functions do not contribute to the system linearization around the equilibrium such that the linear and nonlinear modeling stages are independent. The coefficients of these nonlinear terms are determined via nonlinear optimization. Finally, a nonlinear aerodynamic model is established and applied to aeroelastic applications. To demonstrate the accuracy and efficiency of this method, a two-dimensional, transonic aeroelastic wing with an NACA0012 profile is investigated. The simulation results show that the nonlinear state–space model with modified inputs improves the efficiency and accuracy of transonic aerodynamic nonlinear modeling. Moreover, the aerodynamic model coupled with the structural model can accurately predict the transonic flutter boundary and limit cycle oscillations.

Age features of functional condition of microvessel endothelia

Our research aimed to investigate age-related changes in the functional state of the microvascular endothelium.Матеріали та методи. 390 people were surveyed, divided by age into the following groups: 20-29 (n = 31), 30-39 (n = 22), 40-49 (n = 45), 50-59 (n = 72), 60- 69 (n = 129) and 70-79 years (n = 91). The functional state of the microvascular endothelium was studied by laser Doppler flowmetry (LDF) on the BLF-21D (Transonic Systems Inc, USA) in the middle third of the inner surface of the forearm. The turbidimetric method studied platelet aggregation activity on a two-channel laser platelet aggregation analyzer 23 LA (Biola, Russia). Blood viscosity was determined using a rotary viscometer AKR-2 (Russia) at shear rates of 10-200 s-1 with the calculation of the deformation index (IDE) and erythrocyte aggregation index (IAE). As a result of the research, it was found that there was a statistically significant decrease in the cutaneous rate of skin blood flow volumetric velocity (SBF) at rest and at the peak of post-occlusive reactive hyperemia, as well as a reduction in the recovery time of the CMT to baseline. indicating endothelial dysfunction with ageing from the age of 50-59 years. In persons older than 60 years there is an increase in endothelial dysfunction, which is accompanied by deterioration of hemostasis: increased blood viscosity, increased both spontaneous and induced platelet aggregation activity. Blood viscosity increases statistically significantly from the age of 40. We have drawn the following conclusions: the development of endothelial dysfunction with ageing is characterized by changes in the vasomotor function of the endothelium, its antiplatelet, antiadhesive and antithrombotic properties, which leads to the development of vascular pathology in the elderly. Keywords: functional state of the endothelium; platelet aggregation

The use of microvascular endothelial function indicators to calculate functional age of the microcirculation system

Aim. To find out the possibility of using microvascular endothelial function indicators to determine the biological age (BA) of a person. Materials and methods. 390 patients aged 20–29 years (n = 31), 30–39 (n = 22), 40–49 (n = 45), 50–59 years (n = 72), 60–69 years (n = 129) and 70–79 years (n = 91) were examined. The functional state of the microvascular endothelium was analyzed by laser Doppler flowmetry on a BLF-21D (Transonic Systems Inc, USA) at the internal surface of the middle third of the forearm. Platelet aggregation activity was measured on a two-channel laser platelet aggregation analyzer 23 LA (Biola, Russia) by turbidimetric method, blood viscosity – using a rotational viscometer AKR-2 (Russia) at a shear rate of 10–200 s-1 with the deformation index and erythrocyte aggregation index calculation. Results. There was a statistically significant decrease in the volumetric rate of the skin blood flow (SBF) at rest and at the peak of post-occlusion reactive hyperemia, a reduced recovery time of SBF to baseline values from the age of 50–59 years, indicating endothelial dysfunction with aging. A progression of endothelial dysfunction in persons older than 60 years was accompanied by hemostatic parameters deterioration: increased blood viscosity, increased both spontaneous and induced platelet aggregation activity. Blood viscosity was statistically significantly increased from the age of 40. The formula for calculating BA using indicators of the microvascular endothelium functional state, platelet aggregation capacity and anthropometric indicators was obtained. Conclusions. The formula for calculating human BA using indicators of the microvascular endothelium functional state, platelet aggregation capacity and anthropometric indicators has been developed. Sufficiently high accuracy determination of the microcirculation system functional age based on the developed method has been shown.

Abstract 9386: Marfan Syndrome Mouse Model MgΔ Lpn Presents Alterations in Glomerular Architecture and Increased Renal Vascular Resistance. Losartan Treatment Attenuates These Phenotypes

Introduction: Previously, we have shown that mgΔ lpn murine Marfan syndrome (MFS) model with a fibrillin-1 disruption presents increased Metalloproteinase-9 (MMP-9) expression in the cilliary body in eye. MMP-9 has been related to microfibrils degradation. In this study, we examined the fibrillin-1 and MMP-9 distribution in the kidney and their influence on hemodynamics. Hypothesis: The alteration of fibrillin-1 impacts the glomerular architecture and modify renal hemodynamics. Methods: Female mice at 4 months of age were used: MFS mgΔ lpn mice (n=5); mgΔ lpn treated with losartan for 3 months (n=5); and control wild type mice (n=5). The glomerular structure of the kidney was examined by histology. The distribution and quantification of fibrillin-1 and MMP-9 were analyzed by immunofluorescence assay. Blood flow in the aorta and renal artery was monitored with the probe 2SB-T206 of the Transonic Systems, and the cortical micro-hemodynamic of the kidney was examined by SDF video-microscopy (Sidestream Dark Field Imaging). Results: The mgΔ lpn mice showed reduction of fibrillin-1 deposition and an increase in MMP-9 in the entire kidney tissue, including the glomerular structures. In histologic aspects, the glomerulus showed a reduction of the glomerular area, urinary space, and vascular pole area. The reduced glomerulus dimension possibly squeezes the arteriolar system with a subsequent increase of their vascular resistance. In addition, the cortical microvessels showed a significant reduction in blood flow, and there was an increase in the distribution of microvessels with diameters 6 to 8 μm. Blood flow analysis in the mgΔ lpn showed decreased artery renal flow but did not reveal a difference in aorta blood flow when compared to WT animals. These results indicate vascular resistance in the renal artery. Losartan therapy increased fibrillin-1 and decreased MMP-9 quantifications, improved the glomerulus structures and significantly increased the velocity of the microcirculation blood flow. Conclusions: Alterations in fibrillin-1 modify the glomerular structures and impair kidney hemodynamics. Losartan therapy minimized the renal phenotypes.

Mesenchymal stromal cell treatment of donor kidneys during ex vivo normothermic machine perfusion: A porcine renal autotransplantation study.

Normothermic machine perfusion (NMP) of injured kidneys offers the opportunity for interventions to metabolically active organs prior to transplantation. Mesenchymal stromal cells (MSCs) can exert regenerative and anti-inflammatory effects in ischemia-reperfusion injury. The aims of this study were to evaluate the safety and feasibility of MSC treatment of kidneys during NMP using a porcine autotransplantation model, and examine potential MSC treatment-associated kidney improvements up to 14days posttransplant. After 75min of kidney warm ischemia, four experimental groups of n=7 underwent 14h of oxygenated hypothermic machine perfusion. In three groups this was followed by 240min of NMP with infusion of vehicle, 10million porcine, or 10million human adipose-derived MSCs. All kidneys were autotransplanted after contralateral nephrectomy. MSC treatment did not affect perfusion hemodynamics during NMP or cause adverse effects at reperfusion, with 100% animal survival. MSCs did not affect plasma creatinine, glomerular filtration rate, neutrophil gelatinase-associated lipocalin concentrations or kidney damage assessed by histology during the 14days, and MSCs retention was demonstrated in renal cortex. Infusing MSCs during ex vivo NMP of porcine kidneys was safe and feasible. Within the short posttransplant follow-up period, no beneficial effects of ex vivo MSC therapy could be demonstrated.

The improvement of the functional condition of micro-vascular endothelium among the aged people with metabolic syndrome under quercetin influence

Abstract. The Aim of study is the impact of course application of quercetin on the functional state of the endothelium of the microvessels in elderly people with metabolic syndrome. Materials and methods. We examined 110 patients (55 primary and 55 control patients) with metabolic syndrome (MS). Patients in the main group (n = 55) received quercetin ("Kvertin", chewing tablets manufactured by PJSC "Borshchagovsky KFZ", 80 mg 3 times a day) during 3 months. The control group patients (n = 55) received placebo tablets. The volume velocity of skin blood flow in the region of the middle third of the inner surface of the forearm was determined using the laser doppler flowmetry (LDP) on the apparatus BLF-21D (Transonic Systems Inc, USA). The functional state of the endothelium of microvessels was examined in a sample with post-exclusive hyperemia by clamping shoulder vessels of with a cuff for 3 minutes, in which the pressure exceeded the systolic blood pressure of the subject by 50 mm Hg. Blood pressure was measured by the Erkameter 3000 (Germany) mercury sphygmomanometer on the shoulder artery in accordance with ESH recommendations. Results. In the group of patients receiving quercetin, when performing a test with post-occlusive hyperemia, there was a statistically significant increase in the maximum volumetric velocity of the skin blood flow and the duration of the recovery period, the volumetric velocity of the skin blood flow to the initial level, which indicates an improvement in the vasomotor function of the microvessel endothelium. Improvement of the functional state of the endothelium occurred in 38 of 55 patients (69%) examined and was accompanied by a significant decrease in the level of systolic and diastolic blood pressure. Patients in the control group showed no improvement in the indices of vasomotor function of the microvessel endothelium. Conclusions. Course application of quercetin improves the functional state of the endothelium of microvessels, which helps to lower blood pressure in patients with metabolic syndrome. Key words: metabolic; syndrome; quercetin; functional state of the endothelium; arterial pressure

Precision Banding for High-Flow Hemodialysis Access—Contemporary Outcomes and Failure Predictors

High-flow hemodialysis accesses are increasingly recognized as the source of complications (cardiopulmonary, hand ischemia, access malfunction). Among management strategies (access elongation, revision using distal inflow), precision banding (inflow constriction based on real-time physiologic flow monitoring) offers a technically straightforward approach with potentially low morbidity. However, large contemporary series on banding outcomes (and their predictors) are lacking. Banding was performed with 2-0 doubly looped Prolene over an internal balloon or 3- to 4-mm external mandrel with Transonic thermodilution flow volume monitoring (Transonic Systems, Ithaca, NY). Demographics and clinical characteristics were captured during a 10-year period through prospective databases and some retrospective record review. Multivariable logistic predictive regression models (stepwise selection of clinically relevant variables, P < .10 as entry criterion) were completed for thrombosis within 30 days and rebanding within 1 year as well as during the entire period. In total, 397 patients underwent banding during the study period. One patient had early wound bleeding requiring return to the operating room, and none had discovered complications of band erosion. The infection rate was 0.5% (2/397). Median (interquartile range) follow-up was 157 (52-373) days. Most accesses were upper arm with brachial artery inflow (Table I); half were performed prophylactically on the basis of experienced clinical judgment (mean duplex ultrasound flow 2 L/min), and a third were for steal. Median flow rate reduction was 41%. Among 134 steal patients, only 2 required subsequent ligation to control symptoms. The 30-day thrombosis rate after banding was 13 of 397 (3.3%). Including all thrombotic events (25/397 [6.3%]), median time was 9.5 days (2.0-101.5 days). The rebanding rate within a year was 51 of 397 (13%), and median time from banding to rebanding within 1 year was 133 days; 8 of 397 (2.0%) had to be rebanded within 30 days. During the entire period, 103 of 397 (26%) patients needed rebanding. Multivariate logistic regression analysis showed prosthetic graft as the sole predictor of early thrombosis. After adjustment, only smaller banding diameter was independently associated with any thrombotic event (including those beyond 30 days) and prebanding vein diameter with any need for rebanding (Table II). Precision banding offers an effective, low-morbidity approach for high-flow hemodialysis accesses. Early thrombosis is a rare event after precision banding, although in the long term, one in four patients will require rebanding to control flow.Table IPatient cohort characteristicsVariableTotal cohort (n = 397)Demographic characteristics Median age, years [IQR]59 [48, 73] SexFemale (%)152 (38)Male (%)245 (62) RaceWhite (%)183 (46)Latino (%)132 (33)African-American (%)63 (16)Asian (%)8 (2)Other/unknown (%)13 (3)Comorbidities Hypertension (%)368 (93) Diabetes (%)160 (40) Coronary artery disease (%)129 (32) Dialysis (%)296 (75)Access details SiteForearm (%)50 (13)Upper arm (%)347 (87) TypeAutogenous (%)360 (91)Graft (%)37 (9)Inflow arteryBrachial (%)342 (86)Radial (%)51 (13)Ulnar (%)2 (1) Outflow veinCephalic (%)300 (76)Basilic (%)66 (17)Axillary (%)13 (3)Other (%)16 (4)Access in use at time of banding (%)269 (68) Median preoperative flow rate by Duplex, ml/min [IQR]1975 [1510, 2532]Indication for banding Prophylactic (%)203 (51) Enlarging aneurysm/pseudoaneurysm (%)18 (4) Ischemic steal (%)134 (34) High output heart failure (%)42 (11)Procedural details Time from access creation to banding1234 [534, 2283] Median intraoperative pre-banding flow rate by flow meter, ml/min [IQR]1545 [1210, 2080] Median number of bands [IQR]1 [1, 1] Banding diameter3 [3, 4] Technique of precision bandingIntravascular balloon (%)100 (25)External mandrel (%)297 (75) Median intraoperative post-banding flow rate by flowmeter, ml/min [IQR]640 [445, 865] Median percent flow reduction [IQR]58 [39, 73] Open table in a new tab Table IIUnadjusted univariate and adjusted multivariate logistic regression analysis for association of demographic, access, and procedural characteristics with thrombosis and banding failureVariableThrombosis at 30 daysBanding failure at 1 yearUnadjusted analysisAdjusted analysisUnadjusted analysisAdjusted analysisOdds ratio (95% CI)P valueOdds ratio (95% CI)P valueOdds ratio (95% CI)P valueOdds ratio (95% CI)P valueAge0.97 (0.94-1.0).080.97 (0.94-1.01)0.090.99 (0.97-1.00).080.98 (0.97-1.0).09Male1.4 (0.43-4.66).570.79 (0.44-1.44).45Dialysis at time of banding3.76 (0.48-29.32).210.96 (0.48-1.92).90Access in use at time of banding5.32 (0.68-41.4).111.11 (0.5-2.16).75Indication for banding ProphylacticRefRef Enlarging aneurysm/pseudoaneurysm0.001 (<0.001->999).962.19 (0.58-8.32).72 Ischemic steal0.56 (0.14-2.14).972.39 (1.23-4.64).32 High output heart failure1.22 (0.25-5.95).952.19 (0.84-5.67).63Prosthetic graft5.03 (1.47-17.28).014.96 (1.43-17.25).011.45 (0.57-3.68).44Lower arm access1.30 (0.28-6.05).740.26 (0.06-1.10).070.24 (0.06-1.03).05Inflow artery BrachialRefRef Radial1.23 (0.26-5.71).980.24 (0.06-1.04).98 Ulnar0.001 (<0.001->999).980.001 (<0.001->999).97Outflow vein CephalicRefRef Basilic0.001 (<0.001->999).940.14 (0.66-2.86).20 Axillary2.42 (0.29-20.4).940.57 (0.07-4.54).72 Other4.14 (0.83-20.7).930.46 (0.06-3.58).52Number of bands1.08 (0.32-3.65).911.00 (0.53-1.91).99Pre-banding vein diameter1.00 (0.92-1.09).981.02 (0.98-1.06).31Banding diameter0.47 (0.15-1.51).210.98 (0.56-1.69).93% Flow reduction0.99 (0.97-1.02).631.00 (0.99-1.01).81Intraoperative post-banding flow rate (flowmeter)0.99 (0.99-1.00).571.00 (0.99-1.00).77 Open table in a new tab

P1320ASSESSMENT OF ARTERIOVENOUS FISTULA DYSFUNCTION WITH ACCESS STENOSIS IN HEMODIALYSIS PATIENTS USING SMART-PHONE VIDEOS

Abstract Background and Aims Vascular access dysfunction is one of the leading causes of morbidity and a major contributor to healthcare costs in hemodialysis (HD) patients. Inexpensive, non-invasive tools for routine assessment of vascular access function are needed. Hemodynamically relevant stenoses in arteriovenous fistulas (AVF) lead to a reduction in access flow rate (Qa) and changes in blood flow patterns in the AVF that may be picked up by palpation and auscultation. We hypothesized that these changes in blood flow patterns can not only be felt and heard but also seen, i.e., that they may be detectable in video recordings done with commercially available smartphones after digital motion augmentation. Methods We studied HD patients with AVF dysfunction requiring balloon angioplasty and/or stenting. One-minute video recordings of the skin above the AVF and Qa measurements were conducted before and after the endovascular intervention. Videos were recorded with an iPhone 6S (Apple Inc., Cupertino, CA, USA). Qa was measured by HVT100 endovascular flowmeter (Transonic Systems Inc., Ithaca, NY, USA). Significant access stenosis was defined as a &amp;gt;50% reduction of luminal diameter. Degree of stenosis was assessed by angiography. Frame-to-frame pixel changes in video images were amplified using “Eulerian Video Magnification” (Massachusetts Institute of Technology, MA, USA; http://people.csail.mit.edu/mrub/evm/#code). The time-domain data were then transformed into the frequency-domain signals. Fifty random 10-second segments were sampled per one-minute video, and the frequency with the lowest magnitude (Fmin) was determined in each sample (example shown in Fig. 1). The average Fmin was then assessed for its association with the degree of AVF stenosis. Results Ninety subjects were studied (Table 1). AVF interventions were successful in all patients. Post-intervention Qa (1638 ± 714 ml/min) was on average 1.23-fold higher than pre-intervention Qa (1373 ± 684 ml/min; P&amp;lt;0.01, paired t-test). Subjects were grouped by degree of stenosis, and the number of subjects in each category is shown in Fig. 1B. Higher degrees of stenosis were associated with greater increases in Qa from before to after the intervention (P&amp;lt;0.01, one-way ANOVA; Fig. 1C). Interestingly, the degree of AVF stenosis was also positively related with the change in Fmin from before to after the intervention (P=0.08, one-way ANOVA; Fig. 1D). Conclusion Simple smartphone video recordings of AVF appear to contain frequency-domain information that correlates with hemodynamic changes caused by AVF stenoses. While the Fmin metric employed in our analysis is not ideal, these results should encourage the quest for other parameters that exhibit higher correlations with vascular access dysfunction. If successful, this would allow commercially-available smartphones to be used as ubiquitous tools for quick, non-invasive, ambulatory surveillance of AVF function, thereby allowing timely referrals and avoidance of emergency interventions.

New noninvasive methodology to measure cardiac output in veno-venous extracorporeal membrane oxygenation patients.

Cardiac output (CO) measurement is vital in veno-venous extracorporeal membrane oxygenation patient population to evaluate oxygen delivery and to early identify right heart failure. Standard clinical methods like pulmonary artery thermodilution and transpulmonary thermodilution are known to be inaccurate in the veno-venous extracorporeal membrane oxygenation setting, especially at high levels of recirculation. The aim of the study was to develop a simple noninvasive method to measure CO in patients during veno-venous extracorporeal membrane oxygenation. A mathematical model was developed where CO was analyzed as a combination of two flows: oxygenated blood from extracorporeal membrane oxygenation and less oxygenated mixed venous blood. The system of two mass balance equations for oxygen saturations was introduced to calculate CO. The procedure included measurement of recirculation (ELSA Monitor Transonic Systems Inc. Ithaca, USA) and arterial saturation at two extracorporeal membrane oxygenation flows after temporary pump flow decrease. Mathematic modeling that utilized a crude Monte Carlo method was used to analyze theoretical errors in CO calculations from unknown behavior of venous saturation. The developed concept was retrospectively applied to clinical data archive of 17 adult patients on veno-venous extracorporeal membrane oxygenation that included 52 measurement sessions. Mathematical modeling suggests that proportion of results with error ⩽10% was between 86% and 100% if pre-oxygenated saturation was available and it was between 78% and 86% if pre-oxygenated saturation was not available. Application of two mass balance equation concept to clinical data suggests that as the decrease of the arterial saturation reaches 6% due to flow decrease, then CO calculations becomes highly reliable as 96% (2 standard deviations) of the results has a reproducibility within 6.4%. The mathematical model and clinical retrospective analysis demonstrates that the new methodology has the potential to accurately measure CO in veno-venous extracorporeal membrane oxygenation patients. The next step is validation in animal and clinical settings.

An improved nonlinear reduced-order modeling for transonic aeroelastic systems

In this study, an improved nonlinear reduced-order model composed of a linear part and a nonlinear part is explored for transonic aeroelastic systems. The linear part is identified via the eigensystem realization algorithm and the nonlinear part is obtained via the Levenberg–Marquardt algorithm. The impulsive signal is chosen as the training signal for the linear part and the sinusoidal signal is used to determine the order of the linear part. The training signal for the nonlinear part is selected as the filtered white Gaussian noise with the maximal amplitude and frequency range to be designed via the aeroelastic responses. An NACA64A010 airfoil and an NACA0012 airfoil are taken as illustrative examples to demonstrate the performance of the presented reduced-order model in modeling transonic aerodynamic forces. The aeroelastic behaviors of the two airfoils are obtained via computational fluid dynamics to solve the Euler equation and the Navier–Stokes equation, respectively. The numerical results demonstrate that the presented reduced-order model can successfully predict the nonlinear aerodynamic forces with and without viscous flows. Moreover, the presented reduced-order model is capable of capturing the flutter velocity and modeling complex aeroelastic behaviors, including limit-cycle oscillations, beat phenomena and nodal-shaped oscillations at the transonic Mach numbers with high accuracy.

Off-Design Analysis of Transonic Bypass Fan Systems Using Streamline Curvature Through-Flow Method

Abstract The two-dimensional streamline curvature through-flow modeling of turbomachinery is still a key element for turbomachinery preliminary analysis. Basically, axisymmetric swirling flow field is solved numerically. The effects of blades are imposed as sources of swirl, work input/output and entropy generation. Although the topic is studied vastly in the literature for compressors and turbines, combined modeling of the transonic fan and the downstream splitter of turbofan engine configuration, to the authors’ best knowledge, is limited. In a prior study, the authors presented a new method for bypass fan modeling for inverse design calculations. Moreover, new set of practical empirical correlations are calibrated and validated. This paper is an extension of this study to rapid off-design analysis of transonic by-pass fan systems. The methodology is validated by two test cases: NASA 2-stage fan and GE-NASA bypass fan case. The proposed methodology is a simple extension for streamline curvature method and can be applied to existing compressor methodologies with minimum numerical effort.

Protective effect of Xin-Ji-Er-Kang on cardiovascular remodeling in high-salt induced hypertensive mice: Role ofoxidative stress and endothelial dysfunction

BackgroundXin-Ji-Er-Kang (XJEK) is a Chinese herbal formula that has beenreported to exert effective protection against cardiovascular diseases, such as hypertension and myocarditis. ObjectiveThe aim of the present study was to investigate the effect of XJEK on high-salt-induced hypertensive mice and its possible mechanism. MethodsThe model of hypertension was established through a high-salt diet. Sixty male Kunming mice were randomized into six groups, namely the Control, Model, Low-dose XJEK, Middle-dose XJEK, High-dose XJEK and Fosinopril groups (n=10 per group). Different steady interventions were given to each group: 0.9% Sodium chloride was added to the diet of the Control group and 8% sodium chloride to the diet of the other five groups from the very beginning. An additional 4, 8 and 12 g/kg/day XJEK were intragastrically administered to the Low-dose, Middle-dose and High-dose XJEK groups, respectively, and 2 mg/kg/day fosinopril to the fosinopril group, from the start of week 5. Systolic blood pressure (SBP) was measured weekly from weeks 1 to 8 using the tail-cuff method. At the end of week 8, left ventricular (LV) systolic pressure, LV end-diastolic pressure and rate of rise of LV pressure were examined using a TransonicScisense catheter (Transonic Systems Inc,Ithaca, NY,USA). Endothelium-dependent relaxations induced by acetylcholine were observed in an isolated thoracic aorta ring. Serum and heartsweresampled for the measurement of the following indexes:Serum nitric oxide (NO), superoxide dismutase (SOD) activity and malondialdehyde (MDA) content (determined by colorimetricanalysis); serum angiotensin II(Ang II), endothelin-1, endothelial NO synthase (eNOS), asymmetric dimethylarginine (ADMA), tetrahydrobiopterin (BH4) concentration and l-arginine (determined by enzyme-linked immunosorbent assay); heart to body weight (HW/BW) ratio; myocardial morphological change (determined by HE and VG staining); myocardial eNOS expression (determined by immunofluorescence), and myocardial endothelin receptor A (ETA) expression (determined by western blotting).Results:Statistical data showed that the HW/BW ratio was significantly decreased in the drug treatment group. XJEK treatment could improve the heart systolic and diastolic function and ameliorate hemodynamic parameters and vascular remodeling indexes. Colorimetric results showed that, compared with the model group, XJEK increased serum SOD, NOlevels, and decreased those of serum MDA and Ang II. XJEK reverted changes in cardiac pathology, decreased the myocardial cross-sectional area, collagen volume fraction and perivascular collagen area and improved endothelial dysfunction (ED) by promoting eNOS activity, enhancing NO bioavailability, increasing the expression of BH4 and decreasing ETA content. In addition, treatment with XJEK decreased ADMA content in the myocardium.Conclusion:In conclusion, XJEK mitigates cardiac remodeling in high-salt-induced hypertensive mice. The potential mechanism involves improved oxidative stress and endothelial dysfunction, independently of ameliorating BP.

Effects of quercetin on the indicators of functional state of endothelium of the microvessels in elderly people with metabolic syndrome

Aim. To study the impact of course application of quercetin on the functional state of the endothelium of the microvessels in elderly people with metabolic syndrome.Materials and methods. We examined 50 patients aged 50–75 years with metabolic syndrome (MS). Patients in the main group (n=25) received quercetin («Kvertin», chewing tablets manufactured by P JSC SIC «Borshchahivskiy CPP», 80 mg 3 times a day) during 3 months. The control group patients (n = 25) received placebo tablets. The volume velocity of skin blood flow in the region of the middle third of the inner surface of the forearm was determined using the laser doppler flowmetry (LDP) on the apparatus BLF-21D (Transonic Systems Inc, USA). The functional state of the endothelium of microvessels was examined in a sample with post-exclusive hyperemia by clamping shoulder vessels of with a cuff for 3 minutes, in which the pressure exceeded the systolic blood pressure of the subject by 50 mm Hg.Blood pressure was measured by the Erkameter 3000 (Germany) mercury sphygmomanometer on the shoulder artery in accordance with ESH recommendations.Results. In the group of patients receiving quercetin, a statistically significant increase in the maximum volume velocity of the skin blood flow and the duration of the recovery period of the volume velocity of the skin blood flow to the baseline level were statistically significant, indicating an improvement in the vasomotor function of the endothelium of the microvessels. Functional state Improvement of the endothelium occurred in 52 % of the subjects being accompanied by a decrease in systolic blood pressure by 7.2±1.2 mm Hg. That diastolic blood pressure on 3.24±1.6 mm Hg. The control group patients any improvement in the vasomotor function of the endothelium of the microvessels.Conclusions. Course application of quercetin improves the functional state of the endothelium of microvessels, which helps to lower blood pressure in patients with metabolic syndrome.

Morphophysiological characteristics of skin microcirculation types in patients with Dupuytren’s contracture

Aim– to investigate the patterns of cutaneous microcirculation and their relationship with structural vascular changes in palmar hypoderm in patients with Dupuytren’s disease.Material and methods. In 26 patients with Dupuytren’s contracture aged between 45 and 70 years, the microcirculation of palmar skin was assessed before the planned surgical treatment using ultrasound pulsed Doppler (Minimax-Doppler K, SP Minimax, St. Petersburg, Russia) with a high-frequency sensor of 20 MHz and laser Doppler flowmetry (BLF21, Transonic Systems Inc., USA). The local 3-minute arterial ischemic test was performed in all patients by putting the occlusion cuff on the forearm. Histological analysis of intra-operative tissue specimens was done using light microscopy (Carl Zeiss Primo Star microscope with 3.1 MP UCMOS video camera) MicroCapture Ver 6.6 program was used for data acquisition.Results. The normocirculatory type of hemodynamics (1) was found in 17 % of observations; hyperemic (2) – in 19 %, congestive-spastic (3) – in 42 %, and congestive-static (4) – in 21 %. Histologically type 1 was characterized with initial signs of constrictive arterial remodeling and capillary occlusion, 2 – with marked hyperemia of the microcirculatory bed and diapedesis of blood cells, inflammatory perivascular infiltrates, 3 – with significant narrowing and deformations of lumens in small arteries and hyalinosis of arterioles, 4 – with pronounced polymorphism of capillary loops, significant changes in arteries and veins.Discussion. Hyperemic type of microcirculation reflects high activity of autoimmune inflammation. Congestic-spastic type indicates a significant decrease in the reactivity of precapillary microvessels. Congestic-stasic type is accompanied by the most pronounced constrictive vascular remodeling and denervation of the vascular bed.Conclusion. Dupuytren’s contracture is characterized with predominance of pathological types of microcirculation in palmar skin, which must be taken into account in individualized protocols of additive therapy.

Вазодилататорный эффект сосудистых факторов роста (VEGF) в условиях формирования костной ткани методом дискретной тракции при врожденной сегментарной патологии

The development of the limbs in patients with congenital segmental defects is associated with defects in the vascular system of the same segment. In this case, vascular endothelial growth factors that participate in physiological angiogenesis may have effect on bone tissue formation in ontogenesis and participate in endochondral ossification. In this regard, the aim of the study was to compare the quantitative changes in growth factors (VEGF) and the contractile properties of arterioles under conditions of discrete distraction for congenital pathology of the lower leg bones. Materials and methods Subjects of the study were 12 patients with congenital pseudarthrosis of the lower leg (ICD-10 Q 74.0). Their serum was analyzed using an enzyme immunoassay. Microcirculation in the calf skin was examined by laser flowmetry (BLF21, Transonic Systems Inc., USA). We used the findings obtained from the study of blood serum in 103 somatically healthy people for control. Results Significant imbalance in serum concentrations of endothelial factors and their receptors was detected in the subjects with congenital pathology. As a result of surgical treatment, the imbalance of secretion of vascular growth factors and their receptors increased. Vasodilator effect in the precapillary vessels in the zone of the operated segment in patients with congenital pathology was not revealed by surgical intervention.