Mean Flow Volume Research Articles

Visual assessment of cerebrospinal fluid flow dynamics using 3D T2-weighted SPACE sequence-based classification system.

Flow-related signal void artifacts can be visualized on the T2-weighted (T2W) three-dimensional sampling perfection with application-optimized contrast (3D-SPACE) sequence. Flow void artifacts in the cerebral aqueduct and the fourth ventricle can provide information about cerebrospinal fluid (CSF) flow dynamics. In this study, we aimed to test the performance of the T2W 3D-SPACE sequence in assessing the CSF flow in the aqueduct and/or fourth ventricle. A total of 137 patients (age range = 3-89 years) who underwent CSF flow study were included. The amount of signal loss on T2W 3D-SPACE due to flow in the aqueduct and fourth ventricle was assessed and graded using a 4-point scale of 0 (absence of flow void) to 3 (signal void filling the aqueduct and entire fourth ventricle). A correlation was then sought between the quantitative values obtained by phase-contrast magnetic resonance imaging (PC-MRI) and the amount of signal void in the 3D-SPACE sequence. At the aqueduct level, there was a statistically significant difference in the forward flow velocity and the flow volume among different grades (all P < 0.001). In the grade 3 group, CSF peak systolic flow velocity and mean flow volume were found to be significantly higher than in the other grades (P < 0.001). The mean aqueduct area in the grade 0 group was found to be significantly different from that in the other classes (P < 0.001). The amount of signal loss in the fourth ventricle observed on T2W 3D-SPACE is correlated with the peak systolic velocity and flow volume measured quantitatively in PC-MRI.

Hydraulic parameter estimation for district heating based on laboratory experiments

In this paper we consider calibration of hydraulic models for district heating networks based on operational data. We extend previous theoretical work on the topic to handle real-world complications, namely unknown valve characteristics and hysteresis. We generate two datasets in the Smart Water Infrastructure Laboratory in Aalborg, Denmark, on which we evaluate the proposed procedure. In the first data set the system is controlled in such a way to excite all operational modes in terms of combinations of valve set-points. Here the best performing model predicted volume flow rates within roughly 5 and 10 % deviation from the mean volume flow rate for the consumer with the highest and lowest mean volume flow rates respectively. This performance was met in the majority of the operational region. In the second data set, the system was controlled in order to mimic real load curves. The model trained on this data set performed similarly well when evaluated on data in the operational range represented in the training data. However, the model performance deteriorated when evaluated on data which was not represented in the training data.

The effects of different positions on lower extremity hemodynamics during robot-assisted laparoscopic radical prostatectomy for prostate cancer

PurposeThis study aimed to investigate the effects of two different positions on lower extremity hemodynamics during robot-assisted laparoscopic radical prostatectomy (RARP) for prostate cancer.MethodsA total of 196 patients who underwent RARP in our hospital from February 2020 to March 2022 were included in this study. Among them, 98 patients who underwent surgery with the Trendelenburg position and split-leg position with calf reverse arch from March 2021 to March 2022 were assigned to the observation group, while 98 patients who underwent surgery with the Trendelenburg position and low lithotomy position from February 2020 to February 2021 were assigned to the control group. Using an ultrasound diagnostic instrument to detect the internal diameter, mean blood flow velocity, and mean blood flow volume of the left deep femoral vein at different times, such as the supine position (T0), after 5 minutes of placing the patient in the leg spilt or low lithotomy position (T1), after 5 minutes of pneumoperitoneum (T2), after 5 minutes of head-down tilt or head-down tilt and calf reverse arch (T3), 1.5 hours after the start of surgery (T4), before the removal of CO2 gas (T5), and before the patient left the operating room (T6). As well as the patency of deep venous blood flow in both lower extremities before leaving the operating room,ResultsAfter establishment of pneumoperitoneum, the internal diameter of the deep femoral vein increased significantly, while the mean blood flow velocity and mean blood flow volume decreased significantly in both groups(T0) (P<0.001). With the prolongation of surgical time, the impact on lower extremity hemodynamics in the observation group was smaller than that in the control group. From T2 to T6, the internal diameter of the femoral vein in the observation group was smaller than that in the control group, while the mean blood flow velocity and mean blood flow volume were increased compared to the control group (P<0.05). Before leaving the operating room, the patency of deep venous blood flow in the observation group was better than that in the control group (P=0.003).ConclusionPlacing patients in the Trendelenburg position and split-leg position with calf reverse arch during RARP for prostate cancer has a smaller impact on lower extremity hemodynamics than the low lithotomy position, and can relatively reduce the risk of postoperative deep vein thrombosis.

Comparative Study of Small Vessel (under 0.8 mm) Anastomosed Free Flap and Larger Vessel (over 0.8 mm) Anastomosed Free Flap: Does Supermicrosurgery Provide Sufficient Blood Flow to the Free Flap?

This study aimed to quantify the blood flow of free flaps and compare the blood flow of small vessel (<0.8 mm) and larger vessel (>0.8 mm) anastomosed free flaps. This retrospective study included patients treated successfully with a perforator free flap in the lower extremity between June 2015 and March 2017. A color duplex ultrasound system measured the flow volume through the pedicle by analyzing the mean flow peak velocity, flow volume, and flow volume per 100 g of the flap. A total of 69 patients were enrolled in this study. There was no statistical difference in peak velocity between the small vessel anastomosed free flap (25.2 ± 5.6) and larger vessel anastomosed free flap (26.5 ± 5.4). Flow volume (6.8 ± 4.2 vs. 6.3 ± 3.6) and flow volume/100 g (3.6 ± 3.9 vs. 6.2 ± 6.9) also did not show significant differences. Small vessel (<0.8 mm) free flaps showed similar flow velocity and flow volume to larger vessel (>0.8 mm) anastomosed free flaps. Blood flow to the small vessel anastomosed free flap was sufficient despite its small vessel size.

Exploring ureteroscope design with computational fluid dynamics for improved intra-pelvic pressure.

High intra-pelvic pressure (IPP) during ureteroscopy can lead to complications including pyelovenous backflow, bleeding, and infection. Our primary goal was to identify the best cross-section and orientation of a ureteroscope within a Ureteral Access Sheath (UAS) to minimize IPP and maximize outflow. Our secondary goal was to validate our findings with a UAS prototype. To determine the optimal ureteroscope cross-section within a UAS, four ureteroscopes of equivalent cross-sectional area were simulated within a 10Fr UAS using computational fluid dynamics software COMSOL. We then created a corresponding prototype by securing a 3-0 monofilament suture at the inferior aspect of the 12 Fr outer UAS, inducing an offset to the ureteroscope. Mean flow volumes through a 10/12 Fr UAS occupied by a 9.5-Fr single-use flexible ureteroscope were compared (17 iterations) to those through our prototype UAS. During the simulation, the lowest IPP and highest outflow were seen with an offset circular ureteroscope (41% resistance) compared to a ureteroscope centered in the UAS. The unmodified UAS had an average volume of 30.0mL/min (SD ± 0.35) compared to 33.76mL/min (SD ± 0.90) for the modified UAS (p < 0.05). We found that using a circular ureteroscope positioned along the sidewall maximizes outflow through a circular UAS. We made a prototype UAS to offset the ureteroscope and observed a 12.5% increase in outflow. This approach can potentially decrease IPP during ureteroscopy without impacting inflow or the working channel. Although modifying a ureteroscope is more difficult, it could create an offset without reducing UAS cross-section.

Assessment of Cerebral Arterial Flow Volume Changes with Carotid Vertebral Artery Duplex Doppler Ultrasound in Young-Middle-aged Subclinical Hashimoto Thyroiditis Patients.

To demonstrate cerebral arterial flow volume changes during the hypothyroid, euthyroid, and hyperthyroid phases and comparing between laboratory findings and cerebral arterial flow changes with carotid-vertebral duplex Doppler ultrasound (CVA-DUSG) in subclinical Hashimoto thyroiditis (HT) patients. According to the TSH level, 3 groups were constructed between patient cases. Group 1 (n=29) was the subclinical hyperthyroid group. In this group, the TSH level was between 0.0005 and 0.3 IU/ml. Group 2 (n=175) was the euthyroid group. TSH level in this group was between 0.3 and 4.2 IU/ml. Group 3 (n=76) was the subclinical hypothyroid group. In this group, the TSH level was above 4.2 IU/ml. The control-group (group 4) (n=71) included healthy people. In this group, the TSH level was between 0.3 and 4.2 IU/ml. After obtaining at least three consecutive waves from the bilateral internal cerebral artery and bilateral vertebral artery, volume flows were calculated using CVA-DUSG. Volume flows were calculated as peak systolic velocity + end diastolic velocity/2 × mean arterial diameter. The mean ICA(Internal Carotid Artery) and VA(Vertebral Artery) diameter was measured per ICA and VA. Total cerebral artery flow volume was defined as right ICA + right VA flow volume and left ICA + left VA flow volume. We also demonstrated topographic cerebral artery blood flow changes. Total ICA flow volume was used to assess the anterior part of the brain, total VA flow volume was used to evaluate the posterior part of the brain, right ICA + right VA flow volume was used to assess the right part of the brain, and left ICA + left VA flow volume was used to verify the left part of the brain. There were significant differences between RVA(Right Vertebral Artery) flow volume, LICA (Left Internal Carotid Artery) flow volume, total flow volume, TSH, and T3 and T4 levels in all groups according to the Dunn's multiple comparison test.(p<0.001) Mean TSH level was 0.03 (0.005-0.06) IU/ml in group 1, 2.8 (1.8-3.97) IU/ml in group 2, 7.32 (6.14-9.93) IU/ml in group 3, and 1.76 (1.17-2.49) IU/ml in the control group. The mean T3 level was 4.18 (3.55-5.38) in group 1, 2.88 (2.63-3.16) in group 2, 2.82 (2.49-3.15) in group 3, 3.14 (2.92-3.15) in the control group. The mean T4 level was 1.92 (1.29-2.5) in group 1, 1.16(1.03-1.31) in group 2, 1.01 (0.91-1.16) in group 3, 1.12 (0.97-1.30) in the control group (group 4). Mean total flow volume was 793 (745-898) ml/min in group 1, 742 (684.25-822.5) ml/min in group 2, 747 (692-824) ml/min in group 3, and 700 (673-675) ml/min in the control group. We also demonstrated topographic cerebral arterial volume flow changes with CVA-DUSG. There was a significant difference among all groups in the right and anterior parts of the brain (p < 0.001), and there was a significant difference between groups 1 and 4 in the left part of the brain (p = 0.009). This study demonstrated that total cerebral arterial volume flow increased in the hyperthyroid phase of subclinical HT cases without any internal carotid and vertebral artery diameter changes compared with the euthyroid and hypothyroid phases of subclinical HT and healthy cases. We also verified topographic cerebral arterial blood flow changes in subclinical HT cases with a real-time, easily applicable modality (CVA-DUSG) that does not include X-ray or contrast agents. There was a significant difference between all groups in the right and anterior parts of the brain and there was a significant difference between groups 1 and 4 in the left part of the brain.

Effect of Localized Vibration Massage on Popliteal Blood Flow.

There is a broad scope of literature investigating whole-body vibration (WBV) effects on blood flow (BF). However, it is unclear how therapeutic localized vibrations alter BF. Low-frequency massage guns are advertised to enhance muscle recovery, which may be through BF changes; however, studies using these devices are lacking. Thus, the purpose of this study was to determine if popliteal artery BF increases from localized vibration to the calf. Twenty-six healthy, recreationally active university students (fourteen males, twelve females, mean age 22.3 years) participated. Each subject received eight therapeutic conditions randomized on different days with ultrasound blood flow measurements. The eight conditions combined either control, 30 Hz, 38 Hz, or 47 Hz for a duration of 5 or 10 min. BF measurements of mean blood velocity, arterial diameter, volume flow, and heart rate were measured. Using a cell means mixed model, we found that both control conditions resulted in decreased BF and that both 38 Hz and 47 Hz resulted in significant increases in volume flow and mean blood velocity, which remained elevated longer than the BF induced by 30 Hz. This study demonstrates localized vibrations at 38 Hz and 47 Hz significantly increase BF without affecting the heart rate and may support muscle recovery.

Three-dimensional separation over unswept cantilevered wings at a moderate Reynolds number

We conduct experiments on the structure of the 3D flow fields for unswept cantilevered wings at high angle of attack. Stall cell counter-rotating vortices on the suction surface form for a range of aspect ratios (AR), though AR changes the angle of attack at which the flow separates. Analysis of mean flow volume over the suction surface and near wake shows that the arch vortex forms in the wake and connects to the surface at the stall cell foci. Reynolds stress peaks indicate a strong reliance on the arch vortex location in the mean flow. Spectral analysis of the velocity field at select spanwise planes shows that shedding is coherent but intermittent, and varies strongly along the wingspan.

Thermal management for the shear-rate driven flow of Carreau fluid in a ciliated channel

Cilia beating impacts bio-fluid transport, and the channels with ciliated walls are ubiquitous functions. This innovative study investigates the properties of Careau fluid’s heat and mass transport in a ciliated channel. A 2D wavy channel caused by a metachronal wave of cilia beating is taken, and the flow is considered laminar and incompressible. The viscosities of a generalized Newtonian fluid (Carreau fluid) are affected by both infinite and zero shear rates. It is necessary to convert fixed coordinates to moving coordinates. The system is then clarified on the assumption that the half-width of the channel is significantly less than the wavelength of the metachronal wave and Reynolds number Re is lower. Small Reynolds number and wave number hypotheses simplify the constitutive equations. To resolve the simplified system, a perturbation approach using a stream function is employed. In the end, in this work, the relationship between the thermal transfer coefficient and temperature distribution was shown. various physical factors. This research investigates the effects of several boundary layers on fluid flow. Additionally, there are graphs showing the growth in pressure, velocity field, and streamline. The aim is to provide promising outcomes in creating biomaterial and biomedical devices. It is observed that an accelerate in cilia length accelerates horizontal velocity and time mean volume flow rate and that apparent deceleration emerges in the boundary regions.

Curve Flow-duration-Frequency. The flood modelling regime of the Wadi Mazafran catchment in the north of Algeria

Synthetic modelling of the flood regime is based on the overall knowledge of the hydrological regime in a catchment. The Flow-duration-Frequency (QdF) modelling is used to combine three parameters characterising flood with its mean or exceeded flow, its characteristic duration, and occurrence frequency. Which of these can be established locally at the extreme mean volume flow rates of a catchment reference hydrometric station? The determination of the reference QdF model in mean (volume) and exceeded flows requires two characteristics reflecting the flood regime in a catchment. The first is the characteristic flood duration and the second is the 10-year quantile of the annual maximum instantaneous flow. The comparison of the local situation to the reference QdF models enables to develop the final QdF model of the catchment and therefore the baseline QdF for exceeded and synthetic mono-frequency hydrographs. These are essential components in the study of flood risk mapping and the estimation of the instantaneous peak distribution from mean daily streamflow series.

Effect of primary balloon angioplasty on draining vein diameter and volume flow in patients with arteriovenous fistula: A cohort study

BackgroundChronic kidney disease (CKD) and end-stage kidney disease (ESKD) cause major morbidity and mortality in 10% of the global population with CKD. The most common renal replacement therapy is hemodialysis with arteriovenous fistula (AVF) access. AVF often undergoes maturation failure due to feeding artery and draining vein inadequacy. Mechanical dilatation, such as primary balloon angioplasty (PBA), can overcome AVF maturation failure. The volume flow (VF) and diameter of the draining veins in AVF patients must be known to evaluate the effect of PBA on AVF maturation. This study aims to analyze the impact of PBA on VF and draining vein diameter in ESKD patients undergoing AVF surgery. MethodsA retrospective cohort clinical trial was conducted at our institution. A total of 75 participants had AVF with an arterial diameter >1.5 mm or vein diameter at the AVF creation site of 2–4 mm. The subjects were divided into 2 groups: the intervention group undergoing PBA (n = 36) and the control group, without PBA (n = 39). PBA was performed using a Mustang ballon (3–6 mm, Medtronic). Follow-ups were conducted at 1 week, 2 weeks, and 6 weeks after AVF creation. ResultsBased on the data, the diameter and VF of the draining veins were significantly larger in the intervention group than in the control group (p < 0.001). Furthermore, we found significant differences in the mean diameter and VF of the draining veins between the control and intervention groups at all stages of examination, from preoperatively to 6 weeks postoperatively (p < 0.001). The strength of the analysis was more than 80%. ConclusionPBA can increase the diameter and VF of the draining veins in patients with AVF.

Role of CSF flow parameters in diagnosis and management of persistent postoperative hydrocephalus

ObjectiveTo investigate the extent to which preoperative CSF flow parameters through the aqueduct of Sylvius predicted persistent postoperative hydrocephalus (PPH) in patients with posterior fossa (PF) tumors after surgery. MethodsTwenty patients with PF tumors were enrolled in this prospective cohort study between June 2016 and June 2018. Imaging studies included conventional computerized tomography (CT) scan, magnetic resonance imaging (MRI) with and without gadolinium contrast and phase contrast (cine) magnetic resonance imaging (PC-cMRI). The authors determined the clinical predictors and anthropometric characteristics that caused PPH. CSF flow parameters through the aqueduct of Sylvius were analyzed among patients. In addition, the CSF flow parameters of various clinical predictors associated with PPH were evaluated. ResultsOf the 20 patients, 11 were females, and 9 were males. The mean age of patients was 30.4 ± 16.06. Sixteen patients had PPH, while 4 patients did not (PPH-). The mean aqueductal CSF stroke volume (ACSV) was 4.7 ± 2 (µl/sec), and the mean backflow was 4.8 ± 0.8 (µl/sec). ACSV between PPH + and PPH - groups, were significantly correlated (P = 0.038). However, ACSV between patients with preoperative hydrocephalus and those without preoperative hydrocephalus did not correlate (=0.66). Among other CSF parameters such as peak flow volume (P = 0.211), forward flow volume (P = 0.350), mean flow volume (P = 0.767) and net backward flow volume(P = 0.02), only net backward flow revealed a significant correlation between PPH + and PPH- groups. Metastasis (P = 0.47), tumor location (P = 0.37) and sex (P = 0.92) did not correlate with the need for hydrocephalus treatment. However, the presence of papilledema correlated with the need for hydrocephalus treatment (P = 0.002). ConclusionOur findings showed that although a decreased ACSV correlated with the occurrence of PPH, the presence of preoperative hydrocephalus before posterior fossa tumor resection did not suggest hydrocephalus will persist in surgery.

Assessment of Proximal Radio-median Cubital/Radio-Cephalic Arterio-venous Fistula

The present study aims to conducted the Assessment of Proximal radio-median cubital/radio-cephalic Arterio-venous Fistula. Arterio-venous Fistula is life line for long-term hemodialysis for end stage renal disease patients. The order of preference as per National Kidney Foundation/ Kidney Disease Out Come Quality Initiative (KDOQI) is distal Radio Cephalic fistula is considered as gold standard followed by elbow Brachio Cephalic Fistula, transposed Brachio-Basilic Fistula, forearm arterio-venous graft. This is a cross sectional-prospective interventional study, 05/2017 to 04/2019, JNMC, Wardha, MH, with sample size of 66 cases. Out of 66 cases 25 % patients had diabetes mellitus, 48% cases were suffering from chronic glomerulonephritis, 15 % cases were suffering hypertension, 6 % cases had COPD and another 6 % cases had some cardiovascular disease. About 54 % cases had previous access failure. In our study the mean flow volume for AV fistula in proximal forearm was 485± 291 ml/minon postoperative day1, 695 ± 298 on postoperative day 7 and 755± 347 ml/min. Overall postoperative complications in 12% cases was reported in our case study though Yilmiz et al reported postoperative complications in 15% cases.

Smoothing the steep microsurgery learning curve: considering alternative suture sizes for early-stage microsurgery training with in vivo rat models.

BackgroundLaboratory microsurgery training using invivo rat models is essential for clinical operation. However, challenges existin a structured training course when students transition from a non-livingmodel exercise to a living one. In the present article, we first demonstratethis steep learning curve in early-stage microsurgery training. We then proposethe potential solution of using various sizes of sutures for different trainingpurposes.MethodsTwoseparate preliminary studies were included. First, we reviewed the records of25 students enrolled in our basic microsurgery training course. Each studentcompleted exercises in a non-living model before graduating to a live animalmodel where their performance on end-to-end arterial and venous anastomoses wasevaluated. Second, we examined the feasibility of different suture sizes in amillimeter microvascular anastomosis. Four groups of identical procedures inrat femoral artery were completed using sutures from 8-0 to 11-0. Patency rateand mean blood flow at 60 min post-op were measured and compared.ResultsThirty-minute patency rates for firstarterial and venous anastomoses were 18/25 and 14/25. Those students who hadnon-patent anastomoses spent significantly longer time than those who hadpatent ones (p<.05). For varioussuture sizes, all groups achieved a 100% patency rate. No significantdifferences were found between the mean blood flow volume at 60 min post-op (p>.05).ConclusionsSteep learning curve existed in the early-stagemicrosurgery training when transitioning from non-living to living exercisemodels. The feasibility of using various suture sizes in millimeter anastomosismay be a potential solution for instructors to ease this steep learning curve.Level of Evidence: Not gradable

Eye-Neck Integrated Ultrasound in Idiopathic Intracranial Hypertension and Cerebral Venous Sinus Thrombosis.

Background: The clinical presentation of cerebral venous sinus thrombosis (CVST) overlaps with that of idiopathic intracranial hypertension (IIH), but no screening tool exists. We investigated the role of eye-neck integrated ultrasound in the diagnosis and differentiation of IIH and CVST.Methods: Twenty IIH patients, 30 CVST patients, and 40 healthy controls were retrospectively analyzed. The ultrasonographic optic nerve sheath diameter (ONSD) and hemodynamic characteristics of the internal jugular veins (IJVs) were recorded. The cerebrospinal fluid opening pressure was measured after ultrasonic examination.Results: The ONSD was significantly larger in IIH patients than in controls (4.71 ± 0.41 vs. 3.93 ± 0.24 mm, p < 0.001). The ONSD cut-off for IIH diagnosis was 4.25 mm (AUC = 0.978; 95% CI: 0.95–1.0, p < 0.001, sensitivity: 90%, specificity: 93%). In the CVST group, 22 (73.3%) patients had elevated intracranial pressure (ICP); the mean ONSD was significantly higher in patients with increased ICP than in those without (4.43 ± 0.33 vs. 3.95 ± 0.17 mm, p < 0.001). The mean blood flow volume (BFV) was significantly reduced in CVST patients (425.17 ± 349.83 mL/min) compared to that in controls (680.37 ± 233.03 mL/min, p < 0.001) and IIH patients (617.67 ± 282.96 mL/min, p = 0.008). The optimal BFV cut-off for predicting CVST was 527.28 mL/min (AUC = 0.804, 95% CI: 0.68–0.93, p < 0.001, sensitivity: 80%, specificity: 78%). The velocity of the unilateral IJVs-J3 segment decreased or remained constant during deep inspiration (abnormal respiratory modulate blood flow test, ARMT) in 32.5% of controls, with no bilateral ARMT. The prevalence of bilateral ARMT was 25% in IIH patients (χ2 = 12.9, p = 0.005) and 27% in CVST patients (χ2 = 17.6, p = 0.001).Conclusion: Eye-neck integrated ultrasound is an easily available bedside technique to assess ICP and hemodynamic characteristics of IJVs. ONSD measurement can identify patients with increased ICP, and reduced IJV BFV may aid the differentiation of CVST and IIH.

Oversized balloon angioplasty for endovascular maturation of arteriovenous fistulae to accelerate cannulation and to decrease the duration of catheter use.

The functional autologous arteriovenous fistula is considered the best vascular access for patients on hemodialysis. Some fistulae exhibit maturation problems after creation and do not reach adequate vessel diameter and flow in dialysis. The aim of this study was to describe our technique of oversized balloon angioplasty for assisted maturation of arteriovenous fistulae to accelerate the cannulation and to decrease the time of catheter use and its outcome. A retrospective analysis of balloon-assisted procedures for maturation failure was performed in a single center between October 2011 and January 2019. Patients underwent imaging procedures to identify stenosis, followed by angioplasty using oversized high-pressure balloons from the anastomosis to the deep venous outflow tract. The flow volume, time interval of use of the fistula and removal of the catheter, patency rates, and complications rates were evaluated. Seventy-eight patients underwent 124 balloon angioplasty procedures. Technical and clinical success was achieved in 91% of the cases. In patients in whom maturation was successful, the fistula was cannulated in a mean time of 5 days after the procedure (range, 1-20 days). On average, catheter removal was performed 14 days (range, 5-33 days) after the maturation procedure. The mean flow volume in the fistula before the procedure was 276 ml/min (range, 122-488 ml/min) and 24 h after the maturation was 1014 ml/min (range, 760-1800 ml/min).The primary patency rate at 3, 6, and 12 months was 87.3%, 66.2%, and 50.7%, respectively. Assisted primary patency was 100% at 3 months, 92.9% at 6 months, and 90.0% at 12 months. Minor complications occurred in 18% of cases, and major complications in 4.8%. The oversized balloon-assisted arteriovenous fistula maturation technique is safe and effective, allowing the cannulation of the fistulae a few hours or days after the procedure and decreasing the time of catheter use.

VOLume flow assistance for optimizing outcomes of dysfunctional autologous arteriovenous fistula Angioplasty: the VOLA Pilot Study.

To investigate the feasibility of VF-assisted angioplasty (VFA) in dysfunctional AVF using sequential intraprocedural duplex ultrasound (DUS), to utilize intraprocedural VF as a quantifiable, functional endpoint in endovascular treatment. This prospective study included 20 consecutive patients (23 lesions; 16 men; mean age 67 ± 16 years) with dysfunctional AVF undergoing fluoroscopically guided balloon angioplasty between June 2019 and May 2020. Primary endpoints were quantification of outcome using sequential DUS VF analysis following each dilation, 6-month target lesion re-intervention (TLR)-free rate, standard technical success, procedural success (achievement of a postprocedural VF value equal (or 10% less) or superior to the baseline steady-state access), and correlation between procedural success and TLR-free rate. Secondary endpoints included 6-month lesion late lumen loss (LLL), correlation between balloon diameter used and intraprocedural VF values, and correlation between VF and LLL at 6 months follow-up. Mean VF increase was 168.5% ± 102.5% (range: 24.24-493.33%). Procedural success was 80% (16/20 cases). VFA improved procedural success by 20% (4/20 cases) compared to standard assessment (< 30% residual stenosis and palpable thrill). TLR-free rate was 78.3% and 67.3% at 6 and 12 months. Significantly less TLR was noted in cases of procedural success (82.4% vs. 66.7% 6 months; p = 0.041). Unweighted linear regression showed a significant positive relationship between diameter of balloon and VF (146.9 ± 42.3 mL/min VF gain per mm of balloon diameter; p = 0.001, R2 = 0.23) and a significant negative relationship between LLL and VF decline at follow-up (102.0 ± 34.6 mL/min loss per mm of LLL; p = 0.01, R2 = 0.35). Optimal VF cutoff value and percentile increase to predict access failure were 720 mL/min (sensitivity 58.3%, specificity 71.4%) and 153% (sensitivity 66.7%, specificity 85.7%), respectively. Intraprocedural VF assessment could be used to optimize AVF angioplasty. • A newly proposed functional endpoint of angioplasty in dysfunctional dialysis fistula was evaluated and angioplasty outcome was quantified using volume flow (VF) assessment with sequential intraprocedural DUS. • Intraprocedural VF assessment improved immediate procedural success; increased balloon diameter was correlated with VF gain and late lumen loss with VF decline. • Intraprocedural VF values ≥ to baseline steady-state values were correlated with less re-interventions.

Vascular sound visualization system is useful for monitoring and surveillance of vascular access.

Vascular access (VA) is a lifeline for maintenance hemodialysis patients. Monitoring and surveillance of VA, therefore, play an important role for maintaining VA patency. Surveillance needs special apparatus to estimate the VA function, while, monitoring including physical examination does not usually need such devices but highly skill-dependent and qualitative. We report the clinical utility in monitoring and surveillance of VA using a newly developed electronic stethoscope and vascular sound visualization application. One hundred eight patients participated in the study. The vascular sounds were collected using the electronic stethoscope, converted into digital data, sent wirelessly to a personal computer, and then calculated. The units for the calculated intensity of the vascular sound were decibel [dB]. The intensity, however, was normalized as INDEX values ranging from 0 to 99 for practical use. Correlation between INDEX and the mean flow volume (mFV) and resistance index (RI) of brachial artery measured by Doppler ultrasound sonography were examined for VA surveillance. INDEX was continually measured at each dialysis session in ten patients who underwent the angioplasty for VA monitoring. INDEX significantly correlated with the mFV (coefficient of correlation value = 0.68, p < 0.001) and RI (coefficient of correlation value = -0.51, p < 0.001) of brachial artery. Using the calculated cut-off values, the accuracy of INDEX for the diagnosis of AVF dysfunction ranged from 66% to 82%. INDEX attained the peak just after the angioplasty of culprit lesions and gradually decreased from one patient to another. These results suggest that vascular sound visualization system can be useful in VA monitoring and surveillance for detecting and predicting the access stenosis.

Ultrasonographic digital blood flow measurement in professional baseball pitchers – A quantitative and comparative study with non-throwers

BackgroundVascular disorders in throwing athletes can occur from the thoracic outlet to the fingertips. The occurrence of these disorders around the shoulder is well known, and treatment options have been established for them. However, the occurrence of vascular pathology in the digital arteries in elite baseball pitchers is unclear, and treatment options have not yet been established. We hypothesized that asymptomatic professional baseball pitchers often have existing pathological changes in their digital blood flow; therefore, we quantitatively measured the blood flow in the index finger using ultrasonography and compared the results to those of non-baseball players. MethodsSeven asymptomatic professional baseball pitchers (pitcher group) and 11 healthy volunteers (control group) were included. The flow velocity, flow volume and vessel resistance index of the ulnar digital artery of the index finger were measured just distal to the proximal interphalangeal joint using pulsed wave Doppler in two positions: 1) with the proximal interphalangeal (PIP) joint relaxed (10–15° flexed) and 2) with the PIP joint passively extended (0–5°). ResultsThe mean flow velocity and flow volume were lower in the extended position than in the relaxed position in both groups. In the dominant hand, which was the throwing hand in the pitcher group, the mean flow velocity and the flow volume in the relaxed position were significantly lower in the pitcher group than in the control group. The vessel resistance index in the relaxed position of the dominant hand was significantly higher in the pitcher group than in the control group. In the nondominant hand, there was no significant difference in any parameter between the two groups. ConclusionsAsymptomatic professional baseball pitchers may have a pathological change in digital blood flow in the throwing hand. As treatment options for this condition have not yet been established, it is of utmost importance to carry out periodic examination and prevention before the condition progresses to the symptomatic end stage.

Achievable aspiration flow rates with large balloon guide catheters during carotid artery stenting

BackgroundEmergency carotid artery stenting (CAS) is a frequent endovascular procedure, especially in combination with intracranial thrombectomy. Balloon guide catheters are frequently used in these procedures. Our aim was to determine if mechanical aspiration through the working lumen of a balloon occlusion catheter during the steps of a carotid stenting procedure achieve flow rates that may lead to internal carotid artery (ICA) flow reversal which consecutively may prevent distal embolism.MethodsAspiration experiments were conducted using a commercially available aspiration pump. Aspiration flow rates/min with 6 different types of carotid stents inserted into a balloon guide catheter were measured. Measurements were repeated three times with increasing pressure in the phantom. To determine if the achieved aspiration flow rates were similar to physiologic values, flow rates in the ICA and external carotid artery (ECA) in 10 healthy volunteers were measured using 4D-flow MRI.ResultsAspiration flow rates ranged from 25 to 82 mL/min depending on the stent model. The pressure in the phantom had a significant influence on the aspiration volume. Mean blood flow volumes in volunteers were 210 mL/min in the ICA and 101 mL/min in the ECA.ConclusionsBased on the results of this study, flow reversal in the ICA during common carotid artery occlusion is most likely achieved with the smallest diameter stent sheath and the stent model with the shortest outer stent sheath maximum diameter. This implies that embolic protection during emergency CAS through aspiration is most effective with these models.