Peak Systolic Velocity Measurements Research Articles

Simulation for competency assessment in vascular and cardiac ultrasound.

Healthcare providers who use peripheral vascular and cardiac ultrasound require specialized training to develop the technical and interpretive skills necessary to perform accurate diagnostic tests. Assessment of competence is a critical component of training that documents a learner's progress and is a requirement for competency-based medical education (CBME) as well as specialty certification or credentialing. The use of simulation for CBME in diagnostic ultrasound is particularly appealing since it incorporates both the psychomotor and cognitive domains while eliminating dependency on the availability of live patients with a range of pathology. However, successful application of simulation in this setting requires realistic, full-featured simulators and appropriate standardized metrics for competency testing. The principal diagnostic parameter in peripheral vascular ultrasound is measurement of peak systolic velocity (PSV) on Doppler spectral waveforms, and simulation of Doppler flow detection presents unique challenges. The computer-based duplex ultrasound simulator developed at the University of Washington uses computational fluid dynamics modeling and presents real-time color-flow Doppler images and Doppler spectral waveforms along with the corresponding B-mode images. This simulator provides a realistic scanning experience that includes measuring PSV in various arterial segments and applying actual diagnostic criteria. Simulators for echocardiography have been available since the 1990s and are currently more advanced than those for peripheral vascular ultrasound. Echocardiography simulators are now offered for both transesophageal echo and transthoracic echo. These computer-based simulators have 3D graphic displays that provide feedback to the learner and metrics for assessment of technical skill that are based on transducer tracking data. Such metrics provide a motion-based or kinematic analysis of skill in performing cardiac ultrasound. The use of simulation in peripheral vascular and cardiac ultrasound can provide a standardized and readily available method for training and competency assessment.

Fetal middle cerebral artery Doppler to time intrauterine transfusion in red-cell alloimmunization: a randomized trial.

To evaluate whether Doppler measurement of middle cerebral artery peak systolic velocity (MCA-PSV) for timing subsequent intrauterine transfusions (IUTs) in fetuses that had undergone one IUT for anemia secondary to red-cell alloimmunization is non-inferior to timing based on expected decrease in fetal hematocrit (Hct) or fetal hemoglobin level, without compromising infant hemoglobin at birth. This was an international, pragmatic multicenter randomized controlled trial. Women with a pregnancy complicated by fetal anemia secondary to red-cell alloimmunization (due to any antibody alone or in combination), as indicated by the need to undergo a single IUT, were eligible for inclusion. Women were randomized to the determination of timing of further transfusion(s) by Doppler measurement of MCA-PSV (MCA-PSV Group), with a serial upward trend of values >1.5 multiples of the median considered indicative of the need for another IUT, or timing of transfusion by a decrease in fetal Hct (fetal Hct Group), with subsequent IUTs timed according to an estimated fall in fetal Hct of 1% per day or fetal hemoglobin of 0.3 g/dL per day, to maintain fetal hemoglobin level between 7 and 10 g/dL. The primary outcome was infant hemoglobin level measured at birth. A total of 71 women were randomized, 36 to the MCA-PSV Group and 35 to the fetal Hct Group. Median gestational age at randomization was 30.3 weeks, the majority of women were Caucasian and non-smokers, 9.9% of women had Kell alloimmunization, and 14% of fetuses were hydropic at their first IUT. No statistically significant differences between the two treatment groups were observed with regard to mean hemoglobin levels at birth (MCA-PSV Group, 10.36 ± 3.82 g/dL vs fetal Hct Group, 12.03 ± 3.14 g/dL; adjusted mean difference -1.56 g/dL (95% CI, -3.24 to 0.13 g/dL); P = 0.070), or the number of IUTs performed after randomization (MCA-PSV Group, 1.75 ± 1.79 vs fetal Hct Group 1.80 ± 1.32; adjusted relative risk 0.88 (95% CI, 0.61-1.26); P = 0.474). There was no statistically significant difference between the two groups with respect to the risk of adverse infant outcomes related to alloimmunization or procedure-related complications. Both Doppler measurement of MCA-PSV and estimation of the decrease in fetal Hct or hemoglobin can be used to determine the timing of second and subsequent IUTs in fetuses with red-cell alloimmunization. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Uterine artery pulsatility index in the first trimester: assessment of intersonographer and intersampling site measurement differences

Objective: To determine intersonographer, intersampling site pulsatility index differences in the ascending branch of the uterine artery (UtA-PI) and their effect on detection rates (DR) for early onset preeclampsia (PE).Methods: A prospective observational study was conducted including 52 women with singleton viable pregnancy at 11–13 weeks’ gestation. Consecutive bilateral UtA-PI measurements were performed by two sonographers. Both sonographers hold the Fetal Medicine Foundation (FMF) uterine artery Doppler assessment competency certificates. Sonographer “A” underwent mentorship-based specialist training at the FMF; whilst sonographer “B” is a fetal maternal specialist who was deemed competent to measure UtA-PI based on completion of the FMF online course. Both sonographers were unaware of each other’s UtA-PI and peak systolic velocity (PSV) measurements throughout the study. UtA-PI was measured by sonographer “A” at 1, 2 and 3 cm distally from the internal os. UtA-PI minimum (“Low-PI”) and mean (“Mean-PI”) were determined. Intraclass correlation (ICC), Bland–Altman analysis and Wilcoxon signed rank test were performed to determine bias, 95% limits of agreement (LOA) for intersonographer and intersampling site differences. Simulation studies were performed to determine the effect on early onset PE screening DR.Results: (1) Intersite assessment indicated that UtA-PI and PSV decreased by 7–8% per centimeter relative to the measurement taken at the internal os; (2) Sonographer “B” UtA-PI measurements were significantly lower than those of sonographer “A” for “Low-PI” (p = .001), “Mean-PI” (p = .002) and PSV (p = .004) determined by Wilcoxon signed rank test. The mean reduction in “Low-PI”, “Mean-PI” and PSV of sonographer “B” relative to sonographer “A” were 14.04%, 11.09% and 10.99%, respectively; (3) Measurements taken by sonographer “B” at the level of the internal os were comparable to measurements taken by sonographer “A” at 2 cm distal to the internal os (low-PI: p = .98, Mean-PI: p = .49 and PSV: p = .24); (4) Between sonographer ICC for UtA-PI was asymmetrical strong (left ICC = 0.72, 95%CI: 0.51–0.84) to fair (right ICC = 0.38, 95%CI: −0.08–0.64); and (5) The 14% mean intersonographer difference in lowest UtA-PI would have resulted in an 7% difference in PE screening performance.Conclusions: The measurement of UtA-PI is sampling site dependent with the potential for significant intersonographer differences despite the availability of a prescriptive measurement protocol. This is an important observation as it implies that sonographer “B” inadvertently measured the UtA-PI at a distal site, not at the level of internal os, compared to those measured by sonographer “A”, resulting in a lower DR for early onset PE.

Pulmonary Vein Doppler Patterns in Infants with Single Right Ventricle Anomalies After Initial Staged Palliations.

The aim of this study was to describe serial changes in echocardiographic Doppler pulmonary vein flow (PVF) patterns in infants with single right ventricle (RV) anomalies enrolled in the Single Ventricle Reconstruction trial. Measurement of PVF peak systolic (S) and diastolic (D) velocities, velocity time integrals (VTI), S/D peak velocity and VTI ratios, and frequency of atrial reversal (Ar) waves were made at three postoperative time points in 261 infants: early post-Norwood, pre-stage II surgery, and 14months. Indices were compared over time, between initial shunt type [modified Blalock-Taussig shunt (MBTS) and right ventricle-to-pulmonary artery shunt (RVPAS)] and in relation to clinical outcomes. S velocities and VTI increased over time while D wave was stable, resulting in increasing S/D peak velocity and VTI ratios, with a median post-Norwood S/D VTI ratio of 1.14 versus 1.38 at pre-stage II and 1.89 at 14months (P<0.0001 between intervals). MBTS subjects had significantly higher S/D peak velocity and VTI ratios compared to RVPAS at the post-Norwood and pre-stage II time points (P<0.0001) but not by 14months. PVF patterns did not correlate with survival or hospitalization course at 1year. PVF patterns after Norwood palliation differ from normal infants by having a dominant systolic pattern throughout infancy. PVF differences based upon shunt type resolve by 14months and did not correlate with clinical outcomes. This study describes normative values and variations in PVF for infants with a single RV from shunt-dependent pulmonary blood flow to cavopulmonary blood flow.

Personalized treatment with immunoadsorption and intravenous immunoglobulin in a case of severe Rh alloimmunization during pregnancy unresponsive to plasma – exchange

IntroductionDespite prophylaxis, a small proportion of RhD-negative women may develop anti-D antibodies after a sensitizing event occurring during pregnancy or delivery of a D-positive baby. Intrauterine transfusion (IUT) is the treatment of choice in case of fetal anemia, but it cannot be performed early during pregnancy. Combined treatment with therapeutic plasma-exchange (TPE) and intravenous immunoglobulin (IVIG) can avoid or delay IUT. Immunoadsorption (IA) could represent a more effective treatment in selected cases. Case reportWe report a D-negative female with a history of induced abortion and hydrops fetalis, referred at 8 weeks of gestation with a high anti-D titer. Despite implementing a TPE-IVIG protocol, the patient experienced a spontaneous abortion. At the beginning of her fourth pregnancy, only after a partially effective intensive TPE course, cycles of IA-IVIG were performed. Despite a suboptimal response on the anti-D titer, Doppler ultrasonographic measurements of the fetal middle cerebral artery peak systolic velocity first showed evidence of anemia at 30 weeks of gestation and a IUT was required. After the IUT, anemia persisted with a subsequent dramatic rise in titer, requiring an emergent cesarean section. The infant subsequently underwent successful treatment with IVIG, phototherapy and exchange transfusion and was discharged 7 weeks later without neurological deficits. DiscussionThe treatment of high titer anti-D antibodies during pregnancy may require a multidisciplinary approach with utilization of different apheresis strategies in order to have a successful pregnancy outcome.

The efficacy of forceful ankle and toe exercises to increase venous return: A comprehensive Doppler ultrasound study.

Objective Venous stasis is a risk factor for venous thromboembolism. We aimed to determine the efficacy of forceful foot exercises for actuation of the calf muscle pump to counteract stasis. Methods We examined 20 seated healthy subjects. The peak systolic velocity at the level of the popliteal vein was assessed by Doppler ultrasound. Results The mean peak systolic velocity measurements (in cm/s) were as follows: baseline = 5.6; ankle plantar flexion with toe flexion = 91.0; toe touch heel lift = 107.4; ankle dorsiflexion with toe extension = 193.6; isolated flexion of all toes = 118.8; ankle plantarflexion with 100 and 250 Newton forefoot force = 89.9 and 154.5, respectively. Conclusion All exercises achieved significant increases in peak systolic velocity compared to baseline. Ranking showed that forceful ankle dorsiflexion, plantarflexion with 250 Newtons and forceful flexion of all toes yielded the highest mean peak systolic velocity values (193.6, 154.5, and 118.8 cm/s, respectively).

MP41-13 AMNIOTIC FLUID FOR THE TREATMENT OF ERECTILE DYSFUNCTION

You have accessJournal of UrologyStem Cell Research1 Apr 2017MP41-13 AMNIOTIC FLUID FOR THE TREATMENT OF ERECTILE DYSFUNCTION Michael Zahalsky, Gina Dessources, Melissa Marchand, and Jason Levy Michael ZahalskyMichael Zahalsky More articles by this author , Gina DessourcesGina Dessources More articles by this author , Melissa MarchandMelissa Marchand More articles by this author , and Jason LevyJason Levy More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2017.02.1281AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES There is demand for a non-pharmaceutical approach to treating Erectile Dysfunction (ED). Proflo is Amniotic Fluid (AF) which contains various cytokines and growth factors and is believed to facilitate angiogenesis and decrease inflammation. Therefore, it may prove to be a non-pharmacologic, long-term, cost effective alternative to treat ED. To determining the effectiveness of AF as a sustainable treatment for ED METHODS A retrospective chart review of patients injected with ProFlo AF was performed. Proflo is amniotic fluid from a FDA cleared tissue bank, Vivex. It meets all the criteria to be regulated under the Public Health Service Act section 361. It is minimally manipulated, not combined with anything, not dependent on the metabolic activity of living cells, and being used homologously, since it is from the Genitourinary System and being used on the Genitourinary system. According to FDA draft guidance, Amniotic Fluid is a nonstructural biologic product that serves a biochemical role. A Penile Doppler measuring peak systolic velocity (PSV) and the International Index of Erectile Function Questionnaire (IIEF-5) were used to assess changes in erectile function. Patients were injected with 1cc - 2cc's of AF, and followed up to 6 months. RESULTS 35 patients were injected with ProFlo AF. 15 patients injected with AF had pre and post PSV values, 12 patients had pre and post IIEF-5 scores. The average PSV after Trimix injection before administering AF was 26.65 cm/s. After AF injection in follow up, the average PSV was 37.83 cm/s (two-tailed t-test p-value < 0.005). Similarly, an increase was observed in the IIEF score for the group. IIEF score ranged from 5 to 21.5 before the initial AF injection and were between 8 to 24 after AF injection (two-tailed t-test p-value < 0.05). Patients only complaints were of minimal bruising and pain at the injection site for 2-7 days after injections. CONCLUSIONS Our results are very promising and statistically significant. We found improved erections on ultrasound and by patient reporting. The majority of patients expressed satisfaction with overall results following injections. Previously, safety data from multiple institutions has been reported on ProFlo Amniotic Fluid. This is the first study to evaluate the effectiveness of ProFlo AF injections. ProFlo AF needs larger studies but may prove to be a safe, effective and non-invasive treatment in men with ED. © 2017FiguresReferencesRelatedDetails Volume 197Issue 4SApril 2017Page: e540-e541 Advertisement Copyright & Permissions© 2017MetricsAuthor Information Michael Zahalsky More articles by this author Gina Dessources More articles by this author Melissa Marchand More articles by this author Jason Levy More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Blood flow velocity prediction in aorto-iliac stent grafts using computational fluid dynamics and Taguchi method

Covered Endovascular Reconstruction of Aortic Bifurcation (CERAB) is a new technique to treat extensive aortoiliac occlusive disease with covered expandable stent grafts to rebuild the aortoiliac bifurcation. Post stenting Doppler ultrasound (DUS) measurement of maximum peak systolic velocity (PSVmax) in the stented segment is widely used to determine patency and for follow up surveillance due to the portability, affordability and ease of use. Anecdotally, changes in hemodynamics created by CERAB can lead to falsely high PSVmax requiring CT angiography (CTA) for further assessment. Therefore, the importance of DUS would be enhanced with a proposed PSVmax prediction tool to ascertain whether PSVmax falls within the acceptable range of prediction. We have developed a prediction tool based on idealized models of aortoiliac bifurcations with various infra-renal PSV (PSVin), iliac to aortic area ratios (R) and aortoiliac bifurcation angles (α). Taguchi method with orthogonal arrays (OA) was utilized to minimize the number of Computational Fluid Dynamics (CFD) simulations performed under physiologically realistic conditions. Analysis of Variance (ANOVA) and Multiple Linear Regression (MLR) analyses were performed to assess Goodness of fit and to predict PSVmax. PSVin and R were found to contribute 94.06% and 3.36% respectively to PSVmax. The Goodness of fit based on adjusted R2 improved from 99.1% to 99.9% based on linear and exponential functions. The PSVmax predictor based on the exponential model was evaluated with sixteen patient specific cases with a mean prediction error of 9.9% and standard deviation of 6.4%. Eleven out of sixteen cases (69%) in our current retrospective studies would have avoided CTA if the proposed predictor was used to screen out DUS measured PSVmax with prediction error greater than 15%. The predictor therefore has the potential to be used as a clinical tool to detect PSVmax more accurately post aortoiliac stenting and might reduce diagnostic errors and avoid unnecessary expense and risk from CTA follow-up imaging.

Accuracy of Middle Cerebral Artery Doppler Assessment between 34 and 37 Weeks in Fetuses with Red Cell Alloimmunization

Background: The Doppler measurement of middle cerebral artery peak systolic velocity (MCA-PSV) is considered the gold standard for the noninvasive detection of moderate to severe anemia. However, the accuracy of this test has not been evaluated so far, specifically beyond 34 weeks. Objectives: To assess the accuracy of MCA-PSV to detect moderate to severe fetal anemia and to identify risk factors associated with false-positive and false-negative MCA-PSV values after 34 weeks. Study Design: We studied a retrospective cohort of 150 pregnant women with severe alloimmunization who delivered between 2010 and 2014 and correlated MCA-PSV and fetal or neonatal hemoglobin levels. Results: Sensitivity to predict severe anemia was 69%, with a false-negative rate of 3.6%. When MCA Doppler assessment was normal, the identification of serosal effusions increased the detection rate of severe fetal anemia to 94%, with a false-negative rate of 0.8%. False-positive MCA-PSV measurements were more frequent in fetuses with 1 previous intrauterine transfusion (p = 0.0002), but were not associated with MCA resistance index, intrauterine growth restriction and fetal heart rate. Conclusions: Between 34 and 37 weeks, sensitivity of MCA-PSV Doppler assessment alone is 69% and increases to 94% when also considering signs of hydrops. False-positive MCA-PSV measurements are more frequent in case of former fetal transfusion.

Changes in lower extremity blood flow during advancing phases of pregnancy and the effects of special footwear.

Background During pregnancy, a number of changes affecting venous blood flow occur in the circulatory system, such as reduced vein wall tension or increased exposure to collagen fibers. These factors may cause blood stagnation, swelling of the legs, or endothelial damage and consequently lead to development of venous disease. Objectives The aim of this study is to evaluate the effect of special footwear designed to improve blood circulation in the feet on venous blood flow changes observed during advancing phases of pregnancy. Methods Thirty healthy pregnant women participated in this study at 25, 30, and 35 weeks of gestation. Participants were allocated at random to an experimental group (n = 15) which was provided with the special footwear, or a control group (n = 15). At each data collection session, Doppler measurements of peak systolic blood flow velocity and cross-sectional area of the right popliteal vein were performed using a MySonoU6 ultrasound machine with a linear transducer (Samsung Medison). The differences were compared using Cohen’s d test to calculate effect size. Results With advancing phases of pregnancy, peak systolic velocity in the popliteal vein decreased significantly in the control group, whereas it increased significantly in the experimental group. No significant change in cross-sectional area was observed in any of the groups. Conclusions Findings in the experimental group demonstrated that wearing the footwear tested may prevent venous blood velocity from reducing during advanced phases of pregnancy. Nevertheless, there is a need for further investigation of the beneficial effect on venous flow of the footwear tested and its application.

Computer-aided identification of novel ophthalmic artery waveform parameters in healthy subjects and glaucoma patients

Purpose: Arterial waveform parameters (WPs) are commonly used to monitor and diagnose systemic diseases. Color Doppler Imaging (CDI) is a consolidated technique to measure blood velocity profile in some of the major ocular vessels. This study proposes a computer-aided manipulation process of ophthalmic artery (OA) CDI images to classify and quantify WPs that might be significant in the assessment of glaucoma.Methods: Fifty CDI images acquired by four different operators on nine healthy individuals and 38 CDI images of 38 open-angle glaucoma (OAG) patients were considered. An ad-hoc semi-automated image processing code was implemented to detect the digitalized OA velocity waveform and to extract the WPs. Concordance correlation coefficient (CCC), two-sample t-test and Pearson’s correlation coefficient were used to test for similarities, differences and associations among variables.Results: The OA-CDI images manipulation proposed showed a higher concordance between measured peak systolic velocity (PSV) data and extracted PSV data (0.80≤CCC≤0.98) than on end diastolic velocity (EDV) (0.45≤CCC≤0.63) and resistive index (RI) (0.30≤CCC≤0.58) data. In OAG patients, EDV, RI, subendocardial viability ratio (SEVR), period (T), area ratio (f) and normalized distance between ascending and descending limb (DAD/T) were found statistically correlated to at least one of the following factors: gender, age, ocular medications and year of diagnosis. When compared to healthy individuals, OAG patients OA-CDI profiles showed statistically higher values of f (p &lt; 0.001) and DAD/T (p = 0.002) (p-values corrected by age and gender).Conclusion: The proposed computer-aided manipulation of OA-CDI images allowed to identify DAD/T as a novel WP that vary significantly among healthy individuals and OAG patients, and among female and male OAG patients. Future studies on longitudinal OAG data are suggested to investigate the potential of DAD/T to predict severity and progression of the disease.

Peak Systolic Velocity Measurements with Transcranial Doppler Ultrasound Is a Predictor of Incident Stroke among the General Population in China.

Background and ObjectiveIt is necessary to develop an effective and low-cost screening tool for identifying Chinese people at high risk of stroke. Transcranial Doppler ultrasound (TCD) is a powerful predictor of stroke in the pediatric sickle cell disease population, as demonstrated in the STOP trial. Our study was conducted to determine the prediction value of peak systolic velocities as measured by TCD on subsequent stroke risk in a prospective cohort of the general population from Beijing, China.MethodsIn 2002, a prospective cohort study was conducted among 1392 residents from 11 villages of the Shijingshan district of Beijing, China. The cohort was scheduled for follow up with regard to incident stroke in 2005, 2007, and 2012 by a study team comprised of epidemiologists, nurses, and physicians. Univariate and multivariate Cox proportional hazard regression models were used to determine the factors associated with incident stroke.ResultsParticipants identified by TCD criteria as having intracranial stenosis had a 3.6-fold greater risk of incident stroke (hazard ratio (HR) 3.57, 95% confidence interval (CI) 1.86–6.83, P<0.01) than those without TCD evidence of intracranial stenosis. The association remained significant in multivariate analysis (HR 2.53, 95% CI 1.31–4.87) after adjusting for other risk factors or confounders. Older age, cigarette smoking, hypertension, and diabetes mellitus remained statistically significant as risk factors after controlling for other factors.ConclusionsThe study confirmed the screening value of TCD among the general population in urban China. Increasing the availability of TCD screening may help identify subjects as higher risk for stroke.

Developing Duplex Ultrasound Criteria for Diagnosis of Arteriovenous Fistula Stenosis

The purpose of this study was to determine the best color-flow duplex ultrasound (US) criteria for the detection of significant stenoses in arteriovenous fistulas (AVFs) by comparing US with the angiographic gold standard. Included in this retrospective study were all patients who had both US scans and angiograms of their AVFs performed from December 2008 to July 2015. Comparisons were made between the preoperative US peak systolic velocity (PSV) measurements and the angiographic images looking at the percent diameter reduction in the stenosis. The PSV ratio between the area of stenosis and the normal segment on the inflow side of the stenosis (systolic velocity ratio [SVR]) was also compared with the angiograms. Sensitivity and positive predictive values (PPV) with 95% confidence intervals were calculated. This study included 780 cases of stenotic accesses (47 brachiobasilic, 361 brachiocephalic, and 372 radiocephalic). PSVs of ≥500cm/s predicted a 50% or greater stenosis with a sensitivity of 89% (95% confidence interval 87-91) and PPV of 99% (99-100). At lower PSVs, sensitivity and PPV remained high; however, there were an increased number of false positive cases compared with those at 500cm/sec or greater. The SVR was unreliable in predicting the degree of stenosis in AVF. PSVs of ≥500cm/sec are generally reliable in predicting stenosis of 50% or greater in AVFs.

A method to detect tortuosity of vessel using non imaging ultrasound approach in carotid structure.

Stroke is a leading cause of functional impairments. The typical screening mechanism is to measure localized Peak Systolic Velocity (PSV) and diagnose impending risk associated with stoke by characterizing the PSV values. However, an accurate measurement of PSV using Doppler ultrasound is affected due to the tortuous nature of carotid artery in elder population group as the angle at which acoustic beam strikes the vessel is over or under estimated resulting in improper measure the blood flow velocity. Hence, the proposed approach estimates the degree of tortuosity of the carotid vessel and includes this as calibration parameter to compute an accurate PSV. The proposed system consists of low cost custom-built ultrasound probe and algorithms for computation of tortuosity and calibration of PSV. The method is proposed on a phantom as well as data acquired on the human subjects using non-imaging probe. The results obtained are compared with the ultrasound imaging systems and it is observed to have an error tolerance of ± 2 SD units from ground truth. The proposed approach can be used as point of care non imaging device to screen at risk stroke patients more accurately.

Simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis

Objectives: To evaluate a simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis for screening purposes.Material and methods: A total of 9,493 carotid arteries in 4,748 persons underwent carotid ultrasound examination. Most subjects were 65-year-old men attending screening for abdominal aortic aneurysm. The presence of a stenosis on B-mode and/or a mosaic pattern in post-stenotic areas on colour Doppler and maximum peak systolic velocity (PSV) in the internal carotid artery (ICA) were recorded. A carotid stenosis was defined as The North American Symptomatic Carotid Endarterectomy Trial (NASCET) >20% and a significant stenosis as NASCET >50%. The kappa (κ) statistic was used to assess agreement between methods. Sensitivity, specificity, positive predictive (PPV), and negative predictive (NPV) values were calculated for the greyscale/mosaic method compared to conventional assessment by means of PSV measurement.Results: An ICA stenosis was found in 121 (1.3%) arteries; 82 (0.9%) were graded 20%–49%, 16 (0.2%) were 50%–69%, and 23 (0.2%) were 70%–99%. Eighteen (0.2%) arteries were occluded. Overall, the greyscale/mosaic protocol showed a moderate agreement with ICA PSV measurements for the detection of carotid artery stenosis, κ = 0.455. The sensitivity, specificity, PPV, and NPV for detection of >20% ICA stenosis were 91% (95% CI 0.84–0.95), 97% (0.97–0.98), 31% (0.26–0.36), and 97% (0.97–0.97), respectively. The corresponding figures for >50% stenosis were 90% (0.83–0.95), 97% (0.97–0.98), 11% (0.08–0.15), and 100% (0.99–1.00).Conclusion: Compared with PSV measurements, the simplified greyscale/mosaic protocol had a high negative predictive value for detection of >50% carotid stenosis, suggesting that it may be suitable as a screening method to exclude significant disease.

Development of a Duplex Ultrasound Simulator and Preliminary Validation of Velocity Measurements in Carotid Artery Models.

Duplex ultrasound scanning with B-mode imaging and both color Doppler and Doppler spectral waveforms is relied upon for diagnosis of vascular pathology and selection of patients for further evaluation and treatment. In most duplex ultrasound applications, classification of disease severity is based primarily on alterations in blood flow velocities, particularly the peak systolic velocity (PSV) obtained from Doppler spectral waveforms. We developed a duplex ultrasound simulator for training and assessment of scanning skills. Duplex ultrasound cases were prepared from 2-dimensional (2D) images of normal and stenotic carotid arteries by reconstructing the common carotid, internal carotid, and external carotid arteries in 3 dimensions and computationally simulating blood flow velocity fields within the lumen. The simulator displays a 2D B-mode image corresponding to transducer position on a mannequin, overlaid by color coding of velocity data. A spectral waveform is generated according to examiner-defined settings (depth and size of the Doppler sample volume, beam steering, Doppler beam angle, and pulse repetition frequency or scale). The accuracy of the simulator was assessed by comparing the PSV measured from the spectral waveforms with the true PSV which was derived from the computational flow model based on the size and location of the sample volume within the artery. Three expert examiners made a total of 36 carotid artery PSV measurements based on the simulated cases. The PSV measured by the examiners deviated from true PSV by 8% ± 5% (N = 36). The deviation in PSV did not differ significantly between artery segments, normal and stenotic arteries, or examiners. To our knowledge, this is the first simulation of duplex ultrasound that can create and display real-time color Doppler images and Doppler spectral waveforms. The results demonstrate that an examiner can measure PSV from the spectral waveforms using the settings on the simulator with a mean absolute error in the velocity measurement of less than 10%. With the addition of cases with a range of pathologies, this duplex ultrasound simulator will be a useful tool for training health-care providers in vascular ultrasound applications and for assessing their skills in an objective and quantitative manner.

Surveillance Duplex Ultrasonography of Stent Grafts for Popliteal Aneurysms.

Stent grafts, also known as covered stents, have become an increasingly acceptable treatment for popliteal artery aneurysms. However, endovascular exclusion confers lower primary patency compared to traditional open bypass and exclusion. The purpose of this study was to evaluate whether duplex ultrasonography (DU) can reliably diagnose failing stent grafts placed for popliteal artery aneurysms prior to occlusion. Between June 5, 2007, and March 11, 2014, 21 stent grafts (Viabahn; Gore, Flagstaff, Arizona) were placed in 19 patients for popliteal artery aneurysms. All patients had at least 1 follow-up duplex scan postoperatively. Mean follow-up was 28.9 months (9-93 months). Postoperative DU surveillance was performed in our Intersocietal Accreditation Commission noninvasive vascular laboratory at 1 week postprocedure and every 6 months thereafter. Duplex ultrasonography measured peak systolic velocities (PSVs) and ratio of adjacent PSVs (Vr) every 5 cm within the stent graft and adjacent arteries. We retrospectively classified the following factors as "abnormal DU findings": focal PSV > 300 cm/s, uniform PSVs < 50 cm/s throughout the graft, and Vr > 3.0. These DU criteria were derived from laboratory-specific data that we previously published on failing stent grafts placed for lower extremity occlusive disease. Four of the 21 stent grafts presented with symptomatic graft thrombosis within 6 months of a normal DU. Three of these 4 patients presented with rest pain and underwent thrombectomy (2) or vein bypass (1), and 1 elected for nonintervention for claudication. Our results suggest that surveillance DU using criteria established for grafts placed for occlusive disease may not be useful for predicting stent graft failure in popliteal artery aneurysms.

Twin Anemia Polycythemia Sequence: Current Views on Pathogenesis, Diagnostic Criteria, Perinatal Management, and Outcome.

Monochorionic twins share a single placenta and are connected with each other through vascular anastomoses. Unbalanced inter-twin blood transfusion may lead to various complications, including twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS). TAPS was first described less than a decade ago, and the pathogenesis of TAPS results from slow blood transfusion from donor to recipient through a few minuscule vascular anastomoses. This gradually leads to anemia in the donor and polycythemia in the recipient, in the absence of twin oligo-polyhydramnios sequence (TOPS). TAPS may occur spontaneously in 3-5% of monochorionic twins or after laser surgery for TTTS. The prevalence of post-laser TAPS varies from 2% to 16% of TTTS cases, depending on the rate of residual anastomoses. Pre-natal diagnosis of TAPS is currently based on discordant measurements of the middle cerebral artery peak systolic velocity (MCA-PSV; >1.5 multiples of the median [MoM] in donors and 8 g/dL), and at least one of the following: reticulocyte count ratio >1.7 or minuscule placental anastomoses. Management includes expectant management, and intra-uterine blood transfusion (IUT) with or without partial exchange transfusion (PET) or fetoscopic laser surgery. Post-laser TAPS can be prevented by using the Solomon laser surgery technique. Short-term neonatal outcome ranges from isolated inter-twin Hb differences to severe neonatal morbidity and neonatal death. Long-term neonatal outcome in post-laser TAPS is comparable with long-term outcome after treated TTTS. This review summarizes the current knowledge after 10 years of research on the pathogenesis, diagnosis, management, and outcome in TAPS.

Vertebral and internal mammary artery steal syndrome in patients with hemodialysis access.

Increased flow in the subclavian artery feeding a vascular access for hemodialysis can induce steal phenomena in the vertebral (VA) and internal mammary artery (IMA). The aim of this study was to describe the hemodynamic effects of access flow on the VA and IMA in patients with native fistulas and grafts. Peak systolic (PSV) and end diastolic (EDV) velocity measurements of the VA, IMA and carotid arteries, as well as flow volume measurements of the subclavian artery, were performed. Flow measurements at the side of the vascular access were compared with the contralateral side. Fifty-five patients were consecutively included, most with a radio-cephalic fistula on the left arm with a mean shunt volume of 1156 ml/min. Pathologic flow patterns were observed in the ipsilateral VA in four patients (7.3 %); contralateral VA flow was normal in all patients. Peak systolic velocity of the VA was significantly decreased at the side of the shunt arm with a PSV of 42.6 ± 11.8 cm/s compared to 48.4 ± 15.6 cm/s contralateral (p < 0.05). The IMA flow pattern were normal in all patients. The PSV of the IMA was significantly decreased (p < 0.01) at the side of the shunt arm (87.5 ± 29.1 cm/s) compared to the non-shunt arm (95.9 ± 27.4 cm/s). We describe significant hemodynamic effects of fistulas to the vertebral and internal mammary arteries. Doppler spectral analysis of the vertebral and internal mammary arteries should be integrated in ultrasound, especially in patients with cerebrovascular or cardiac symptoms.

Comparison of Anterior Tibial Bone Microvascular Flow, with Macrovascular Flow during Body Tilt

PurposeThis study determined whether bone blood flow in the tibia is linearly proportional to blood flow of the feeding anterior tibial artery (ATA) during various positions of body tilt. We hypothesize bone microvascular flow is linearly proportional to input blood flow in the feeding ATA.MethodsThe IRB of UC San Diego approved the study of 18 healthy subjects, 10 females and 8 males, aged 26 ± 7 years. All subjects assumed sitting, supine, 6° head‐down tilt (HDT), 15° HDT, 6° head‐up tilt (HUT), and 15° HUT positions for 5min using an inversion table. All positions were randomized except the sitting position, which was the first position to be used as the baseline. An Ultrasound Device noninvasively measured peak systolic velocity of the right ATA with subsequent calculation of blood flow. A customized photoplethysmography (PPG) device non‐invasively measured the right leg's tibial bone microvascular flow. Blood pressure (BP) and heart rate (HR) were recorded during the third minute of each position.ResultsATA marcovascular blood flow increased significantly from the sitting to the 15°HDT (p=0.041). Tibial bone microvascular flow increased significantly in supine compared to sitting position (p=0.013). Tibial bone microvascular flow also increased significantly in both 6°HDT and 15°HDT compared to sitting positions (p=0.011, p=0.010). Furthermore, when comparing tibial microvascular bone blood flow to ATA macrovascular blood flow, the normalized slope for microvascular flow increases more than the normalized slope for macrovascular flow (p&lt;0.001) (Figure 1, one way ANOVA) (Figure 1).ConclusionOur results document that the tibial bone microvasculature is more variable and widely regulated than the feeding arterial vasculature, probably due to precapillary vasoreactivity. The findings of this study are novel and may aid the understanding of various skeletal processes such as bone healing and bone homeostasis.Support or Funding InformationThis study was supported by NASA grant number NNX13AJ12G.