Surveillance duplex ultrasound prompted interventions after carotid endarterectomy.

OBJECTIVE: Current societal guidelines recommend duplex ultrasound (DUS) surveillance beyond 30 days after carotid endarterectomy (CEA) for patients with risk factors for restenosis or who underwent primary closure. However, the appropriate duration of this surveillance has not yet been identified, and the rate at which DUS surveillance prompts intervention is unknown. Multiple calls for decreasing health care spending that does not provide value, including unnecessary testing, have been made. The purpose of this study was to examine the rate of intervention prompted by surveillance DUS on the ipsilateral or contralateral carotid artery after CEA and determine the value of continued surveillance by determining the rate of DUS-prompted intervention. METHODS: A single-center, retrospective chart review of all patients older than 18 years who had undergone CEA from August 2009 to July 2022 was performed. Patients with at least one postoperative duplex in our Intersocietal Accreditation Council-accredited ultrasound lab were included. Exclusion criteria were patients with incomplete medical charts or patients who underwent a concomitant procedure. The primary end point was return to the operating room for subsequent intervention based on abnormal surveillance DUS findings. Secondary end points were the number of postoperative surveillance duplexes, duration of surveillance, and incidence of perioperative stroke. The study participant data were queried for patients who had a diagnosis of stroke that occurred following their procedure. RESULTS: A total 767 patients, accounting for 771 procedures, were included in this study, which resulted in 2145 ultrasound scans. A total of 40 (5.2%) patients required 44 subsequent interventions that were prompted by DUS surveillance scans. The average number of ultrasound scans per patient was 2.8 (range: 0-14), and the average duration of surveillance was 26.4 months (range: 0-155 months). Of the 767 patients, 669 (87.2%) had a unilateral CEA. A total of 62 of 767 (8.1%) patients had planned endarterectomies on the contralateral side based on initial imaging, not prompted by interval DUS surveillance scans. Of 767 patients, 28 (3.7%) patients who underwent CEA had a subsequent procedure for progression of contralateral disease, which was prompted by duplex surveillance scans. The average duration between index CEA and intervention on contralateral carotid was 29.57 months (range: 3-81 months). A total of 11 patients, accounting for 12 procedures, underwent a subsequent procedure for restenosis of their ipsilateral carotid, prompted by duplex surveillance scans. The average duration between index CEA and reintervention on the ipsilateral carotid was 17.9 months (range: 4-70 months). Three of 767 (0.4%) patients in total were identified as having a perioperative stroke. CONCLUSIONS: The overall rate of ipsilateral reintervention after CEA is low. A small percentage of patients will progress their contralateral disease, ultimately requiring surgical intervention. These data suggest that regular duplex surveillance after CEA is warranted for patients with at least moderate contralateral disease; however, the yield is low for ipsilateral restenosis after 36 months based on this single institution study. Further study is needed to better delineate which patients need follow-up to decrease unnecessary testing while still targeting patients most at risk of restenosis or contralateral progression of disease.

Optimizing the diagnostic approach of functional popliteal artery entrapment syndrome.

OBJECTIVE: Functional popliteal artery entrapment syndrome (fPAES) is an underdiagnosed and undertreated etiology of atypical claudication. Symptoms of fPAES include deep posterior muscle cramping and pain with exercise and, unlike anatomic PAES, there are seldom vascular complications. Common noninvasive diagnostic modalities include ankle-brachial index, arterial duplex Doppler ultrasound (DUS) examination, and cross-sectional imaging such as magnetic resonance angiography (MRA). Entrapment can be difficult to reproduce during diagnostic testing, requiring provocative maneuvers. Because we believed different provocative maneuvers provide different diagnostic efficacy, we sought to optimize our diagnostic approach to fPAES. METHODS: We performed a retrospective review of patients before and after optimizing our noninvasive imaging protocol comparing patients with fPAES versus other atypical claudicants with chronic compartment syndrome. RESULTS: Arterial DUS examination and exercise ankle-brachial index were important components of our protocol with a significant decrease in systolic posterior tibial blood pressure of -14 mm Hg after exercise, whereas nonentrapment release patients had an overall increase of 8 mm Hg (P = .006). Arterial DUS examination of the distal PA with forced plantarflexion demonstrated a trend toward an increase in the measured velocity ratio, especially in the middle and distal PA. MRA with stressed plantar flexion findings were positive in 6 of 11 patients with fPAES, with false negatives likely owing to patients' inability to maintain a provocative position for the duration of the MRA. CONCLUSIONS: Diagnosing fPAES is challenging owing to a lack of standardized diagnostic testing and provocative maneuvers. Different maneuvers demonstrated varying diagnostic yields for fPAES. Exercise ABIs were the most reliable vascular laboratory test to detect changes attributable to fPAES and to distinguish it from chronic compartment syndrome. Segmental PA DUS examination seems to be promising as a means of detecting PA impingement. Stress positional MRA effectively demonstrates anatomic PAES, but has a false-negative rate for fPAES.

Discrepancies in clavicle-to-carotid bifurcation length measurements for transcarotid artery revascularization using different imaging modalities.

OBJECTIVE: Transcarotid artery revascularization (TCAR) has emerged as an effective method for carotid artery stenting. However, anatomic eligibility for TCAR is most often limited by an inadequate clavicle-to-carotid bifurcation length of <5 cm. Preoperative clavicle-to-carotid bifurcation distances may be underestimated when using conventional straight-line measurements on computed tomographic angiography (CTA) imaging. We therefore compared clavicle-to-carotid bifurcation lengths as measured by straight-line CTA, center-line CTA, and intraoperative duplex ultrasound (US), to assess potential differences. METHODS: We conducted a single-center, retrospective review of consecutive TCAR procedures performed between 2016 and 2019 for atherosclerotic carotid disease. For each patient, we compared clavicle-to-carotid bifurcation lengths measured by straight-line CTA, center-line CTA using TeraRecon image reconstruction, and intraoperative duplex US with neck extension and rotation. We further assessed patient and imaging characteristics in individuals with a ≥0.5 cm difference among the measurement methods. In particular, common carotid artery (CCA) tortuosity, defined as the inability to visualize the entire CCA from clavicle to carotid bifurcation on both a single coronal and sagittal imaging cut, was examined as a contributing factor for these discrepancies. RESULTS: Of the 70 TCAR procedures identified, 46 had all three imaging modalities available for review. The median clavicle-to-carotid bifurcation length was found to be 6.4 cm (interquartile range [IQR], 5.4-6.7 cm) on straight-line CTA, 7.0 cm (IQR, 6.0-7.5 cm) on intraoperative duplex US, and 7.2 cm (IQR, 6.5-7.5 cm) on center-line CTA (P < .001). Patients with a ≥0.5 cm difference between their straight-line CTA and either their intraoperative duplex US or center-line CTA measurements were more likely to have tortuous CCAs (60.0% vs 19.1%; P = .01; 51.4% vs 0.0%; P = .01). There were no notable differences in age, gender, prior neck/cervical spine surgery, or neck immobility among these individuals. In patients with tortuous CCAs, duplex US and center-line CTA measurements added 1.0 cm (IQR, 0.6-1.5 cm) and 1.1 cm (IQR, 0.9-1.6 cm) more in length than straight-line CTA measurements, respectively. There was a strong linear correlation between the additional lengths provided by duplex US measurements and those provided by center-line CTA measurements for each individual within the tortuous CCA group (r = 0.83). CONCLUSIONS: The use of straight-line CTA during preoperative planning can underestimate the clavicle-to-carotid bifurcation lengths in patients undergoing carotid revascularization, particularly in those with tortuous CCAs. Both duplex US performed with extended-neck surgical positioning and center-line CTA provide similar and longer carotid length measurements, and should be utilized in patients with tortuous carotid vessels to better determine TCAR anatomic eligibility.

Changes in renal-mesenteric duplex ultrasound velocities after fenestrated and branched endovascular aortic aneurysm repair.

OBJECTIVE: Stenting of renal and mesenteric vessels may result in changes in velocity measurements due to arterial compliance, potentially giving rise to confusion about the presence of stenosis during follow-up. The aim of our study was to compare preoperative and postoperative changes in peak systolic velocity (PSV, cm/s) after placement of the celiac axis (CA), superior mesenteric artery (SMA) and renal artery (RAs) bridging stent grafts during fenestrated-branched endovascular aortic repair (FB-EVAR) for treatment of complex abdominal aortic aneurysms (AAA) and thoracoabdominal aortic aneurysms. METHODS: Patients were enrolled in a prospective, nonrandomized single-center study to evaluate FB-EVAR for treatment of complex AAA and thoracoabdominal aortic aneurysms between 2013 and 2020. Duplex ultrasound examination of renal-mesenteric vessels were obtained prospectively preoperatively and at 6 to 8 weeks after the procedure. Duplex ultrasound examination was performed by a single vascular laboratory team using a predefined protocol including PSV measurements obtained with <60° angles. All renal-mesenteric vessels incorporated by bridging stent grafts using fenestrations or directional branches were analyzed. Target vessels with significant stenosis in the preoperative exam were excluded from the analysis. The end point was variations in PSV poststent placement at the origin, proximal, and mid segments of the target vessels for fenestrations and branches. RESULTS: There were 419 patients (292 male; mean age, 74 ± 8 years) treated by FB-EVAR with 1411 renal-mesenteric targeted vessels, including 260 CAs, 409 SMAs, and 742 RAs. No significant variances in the mean PSVs of all segments of the CA, SMA, and RAs at 6 to 8 weeks after surgery were found as compared with the preoperative values (CA, 135 cm/s vs 141 cm/s [P = .06]; SMA, 128 cm/s vs 125 cm/s [P = .62]; RAs, 90 cm/s vs 83 cm/s [P = .65]). Compared with baseline preoperative values, the PSV of the targeted vessels showed no significant differences in the origin and proximal segment of all vessels. However, the PSV increased significantly in the mid segment of all target vessels after stent placement. CONCLUSIONS: Stent placement in nonstenotic renal and mesenteric vessels during FB-EVAR is not associated with a significant increase in PSVs at the origin and proximal segments of the target vessels. Although there is a modest but significant increase in velocity measurements in the mid segment of the stented vessel, this difference is not clinically significant. Furthermore, PSVs in stented renal and mesenteric arteries were well below the threshold for significant stenosis in native vessels. These values provide a baseline or benchmark for expected PSVs after renal-mesenteric stenting during FB-EVAR.

Effects of plaque characteristics and artery hemodynamics on the residual stenosis after carotid artery stenting.

OBJECTIVE: Carotid artery stenting (CAS) has become an alternative strategy to carotid endarterectomy for carotid artery stenosis. Residual stenosis was an independent risk factor for restenosis, with the latter affecting the long-term outcomes of CAS. This multicenter study aimed to evaluate the echogenicity of plaques and hemodynamic alteration by color duplex ultrasound (CDU) examination and investigate their effects on the residual stenosis after CAS. METHODS: From June 2018 to June 2020, 454 patients (386 males and 68 females) with a mean age of 67.2 ± 7.9 years, who underwent CAS from 11 advanced stroke centers in China were enrolled. One week before recanalization, CDU was used to evaluate the responsible plaques, including the morphology (regular or irregular), echogenicity of the plaques (iso-, hypo-, or hyperechoic) and calcification characteristics (without calcification, superficial calcification, inner calcification, and basal calcification). One week after CAS, the alteration of diameter and hemodynamic parameters were evaluated by CDU, and the occurrence and degree of residual stenosis were determined. In addition, magnetic resonance imaging was performed before and during the 30-day postprocedural period to identify new ischemic cerebral lesions. RESULTS: The rate of composite complications, including cerebral hemorrhage, symptomatic new ischemic cerebral lesions, and death after CAS, was 1.54% (7/454 cases). The rate of residual stenosis after CAS was 16.3% (74/454 cases). After CAS, both the diameter and peak systolic velocity (PSV) improved in the preprocedural 50% to 69% and 70% to 99% stenosis groups (P < .05). Compared with the groups without residual stenosis and with <50% residual stenosis, the PSV of all three segments of stent in the 50% to 69% residual stenosis group were the highest, and the difference in the midsegment of stent PSV was the largest (P < .05). Logistic regression analysis showed that preprocedural severe (70% to 99%) stenosis (odds ratio [OR], 9.421; P = .032), hyperechoic plaques (OR, 3.060; P = .006) and plaques with basal calcification (OR, 1.885; P = .049) were independent risk factors for residual stenosis after CAS. CONCLUSIONS: Patients with hyperechoic and calcified plaques of the carotid stenosis are at a high risk of residual stenosis after CAS. CDU is an optimal, simple and noninvasive imaging method to evaluate plaque echogenicity and hemodynamic alterations during the perioperative period of CAS, which can help surgeons to select the optimal strategies and prevent the occurrence of residual stenosis.

Meta-Analysis of Duplex Surveillance Following Lower Limb Endovascular Intervention.

INTRODUCTION: The aim of this systematic review was to identify the evidence in the literature for limb salvage with the introduction of duplex surveillance. METHODS: A systematic review and meta-analysis was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines (PRISMA) methodology for all studies which compared a group undergoing clinical surveillance with a group undergoing combined clinical and duplex surveillance after endovascular therapy for peripheral arterial disease. MEDLINE, EMBASE, the Cochrane Database for Systematic Reviews, and ClinicalTrials.gov were searched for relevant studies by 2 reviewers. Studies were quality assessed using the ROBINS-I tool. An individual patient data survival analysis and meta-analysis for 1- and 2-year amputation outcomes using a random-effects model were performed. RESULTS: Two low-quality nonrandomized studies met the inclusion criteria. There was a statistically and clinically significant reduction in major amputation in patients undergoing combined clinical and duplex surveillance (log-rank p<0.001). The number needed to treat to prevent 1 amputation at 2 years was 5 patients. At 1 year, the odds ratio (OR) for amputation was 0.22, 95% confidence interval (CI)=0.10-0.48, with no statistical heterogeneity. At 2 years, the numbers of patients were low and the effect on amputation was less certain OR=0.25, 95% CI=0.04-1.58. CONCLUSIONS: Preliminary, low-quality data suggests that there may be a clinically significant reduction in major amputation with the introduction of duplex surveillance. It is recommended that a randomized controlled trial is performed to confirm these findings and identify the anatomical subgroups that benefit the most from surveillance. CLINICAL IMPACT: "Two low-quality studies reveal a significant clinical impact: combined clinical and duplex surveillance markedly reduces major amputations (log-rank p<0.001). At 1-year, the odds ratio for amputation is 0.22 (95% CI=0.10-0.48), emphasizing limb salvage benefits. Despite less certainty at 2-years, a notable absolute risk reduction of 19% is seen, with a number needed to treat of 5. This underscores the urgent need for a randomized controlled trial to validate findings and identify key subgroups. The meta-analysis strongly advocates implementing duplex surveillance for a year post-endovascular interventions, especially in patients fit for reintervention, with important considerations for cost-effectiveness and focused clinical trials."

Quantitative Techniques of Ultrasonography in the Assessment of Femoropopliteal Atherosclerotic Lesions Using Peak Systolic Velocity Ratio: Results From the TURN-UP Study.

PURPOSE: Duplex ultrasound (DUS)-measured peak systolic velocity ratios (PSVRs) are commonly used to evaluate arterial stenosis in lower extremity artery disease (LEAD). However, these measurement methods have not yet been standardized. This study aimed to reveal the influence of measuring methods on PSVR values. METHODS: A 132 femoropopliteal lesions with PSVR ranging from 1.5 to 3.5 evaluated using method A (angle correction 60°, the direction of blood flow, the no or few atherosclerotic changes closest to the lesion proximal side was defined as the nonstenotic area) were included. The following 4 different methods were then compared with method A: method B, angle correction 45°; method C, angle correction 60° measured along the vessel wall; D, angle correction 60°, with the nonstenotic area the lowest peak systolic velocity area; and E, angle correction 60°, with the reference point fixed at 2 cm proximal to the target lesion area. The difference in PSVR values was analyzed using the Bland-Altman method. RESULTS: The mean PSVR value measured by method A was 2.27±0.51, those measured by methods B, C, D, and E were 2.21±0.55, 2.31±0.66, 2.34±0.63, and 2.11±0.63, respectively. The 95% prediction intervals of the differences in PSVR measurements versus A were -0.64 to +0.53 for method B, -0.59 to +0.68 for method C, -0.77 to +0.91 for method D, and -1.12 to +0.79 for method E. CONCLUSION: PSVR values considerably differed between measuring methods. PSVR values by DUS are largely dependent on the measurement methods, which could considerably affect the judgment of LEAD. CLINICAL IMPACT: Due to differences in several DUS measurement methods, the PSVR results could be changed. Therefore, to need further investigations and unification of measurement method.

Effect of anterior communicating artery patency on the flow velocity in bilateral carotid artery stenosis after carotid endarterectomy.

BACKGROUND: The effect of anterior communicating artery (ACoA) patency on the flow velocity of the extracranial carotid arteries is unclear. METHODS: A total of 285 patients with carotid artery stenosis were included between January 2019 and January 2021. All patients received unilateral carotid endarterectomy (CEA). The patients were classified into ACoA-patent (161) and ACoA-nonpatent (124) groups using digital subtraction angiography (DSA) and/or computed tomography angiography (CTA). The peak systolic velocity (PSV) and end-diastolic velocity (EDV) measured by carotid duplex ultrasonography (CDU) were compared between both groups, pre- and post-CEA. RESULTS: There was no significant difference in the risk factors for cerebrovascular disease between the two groups. Within 1 week after CEA, the PSV and EDV on operative and nonoperative carotid (contralateral carotid in the same patient) arteries decreased significantly (both p < 0.01). Comparison of nonoperative carotid artery pre- and post-CEA between the two groups showed that post-CEA PSV and EDV in the ACoA-patent group were significantly lower than that of pre-CEA (PSV and EDV, t = 11.507 and 6.716, respectively, both p < 0.001) (according to the Society of Radiologists in Ultrasound Consensus Conference [SRUCC] PSV standard). There was no significant difference in the ACoA-nonpatent group (PSV: t = 1.924, p = 0.057; EDV: t = 1.237, p = 0.218). In the nonoperative carotid artery of the ACoA-patent group, the degree of stenosis assessed by CDU was inconsistent with that of DSA/CTA (κ = 0.294), whereas that in the ACoA-nonpatent group had a high consistency (κ = 0.982). Among 161 ACoA-patent cases, 68 showed overestimated stenosis. CONCLUSIONS: The patent ACoA increases PSV and EDV, causing an overestimation of carotid artery stenosis.

Mesenteric and renal arterial duplex ultrasound: A review.

Duplex ultrasound examinations of the mesenteric and renal circulations are commonly used to detect disease as well as to follow up patients after open surgery or endovascular intervention. The aims of this review were to present essential elements of these duplex ultrasound examinations as well as conduct a literature review of diagnostic criteria. Documentation of appropriate images and data will aid in an accurate interpretation. Spectral Doppler waveforms from various segments of these arterial systems can contribute both direct and indirect evidence of the presence of disease. Various studies have validated the duplex ultrasound diagnostic criteria which more recently have expanded to include specific criteria for stented vessels. This review presents a summary of the fundamental exam components and diagnostic criteria utilized for mesenteric and renal duplex ultrasound.

Contrast enhanced duplex ultrasound for early postoperative follow-up after endovascular aneurysm repair: Relation to patient's initial risk of complications.

OBJECTIVES: Current guidelines recommend initial postoperative follow-up with computed tomography angiography (CTA) after endovascular aneurysm repair (EVAR). However, CTA has risks associated with ionizing radiations and nephrotoxic contrast agents. We investigated possibilities to replace the initial postoperative CTA with contrast enhanced duplex ultrasound (CE-DUS) in selected patients. METHODS: Out of the 273 consecutive patients who underwent EVAR, 173 were excluded and the 100 patients who underwent CTA and CE-DUS imaging concurrently (≤1 month interval between CTA and CE-DUS imaging) within 60 days after EVAR were analyzed. Patients who underwent EVAR outside the manufacturer's instructions for use or who had endoleaks discovered on intraoperative angiography were classified as the high-risk group, otherwise, they were classified as the low-risk group. Measurements of diagnostic values of CE-DUS ​​related to the detection of complications were calculated using CTA as the gold standard. McNemar's test was performed to compare these values and Pearson correlation coefficient was derived to compare CE-DUS measurements of sac diameters with CTA. RESULTS: In the low-risk group, no difference was observed between CE-DUS and CTA in the detection of EVAR-related complications (sensitivity = 0.95, specificity = 0.93). In the high-risk group, CE-DUS was not as accurate as CTA for the detection of overall EVAR-related complications (sensitivity = 0.57, specificity = 0.86, p = 0.04) and for the detection of complications other than endoleaks (p = 0.02). Regarding sac diameter measurement, there was good agreement between CE-DUS and CTA (r = 0.92, p < 0.001). CONCLUSIONS: First postoperative CE-DUS was reliable for the evaluation of EVAR-related complications compared to CTA in selected patients. Individualized EVAR follow-up strategy using CE-DUS based on the initial risk of EVAR-related complications should be considered.

Artificial intelligence and duplex ultrasound for detection of carotid artery disease.

OBJECTIVE: The aim of this study is to evaluate the feasibility, applicability and accuracy of artificial intelligence (AI) in the detection of normal versus carotid artery disease through greyscale static duplex ultrasound (DUS) images. METHODS: A prospective image acquisition of individuals undergoing duplex sonography for the suspicion of carotid artery disease at a single hospital was conducted. A total of n = 156 images of normal and stenotic carotid arteries (based on NASCET criteria) were evaluated by using geometry group network based on convolutional neural network (CNN) architecture. Outcome was reported based on sensitivity, specificity and accuracy of the network (artificial intelligence) for detecting normal versus stenotic carotid arteries as well as various categories of carotid artery stenosis. RESULTS: The overall sensitivity, specificity and accuracy of AI in the detection of normal carotid artery was 91%, 86% and 92%, respectively, and for any carotid artery stenosis was 87%, 82% and 90%, respectively. Subgroup analyses demonstrated that the network has the ability to detect stenotic carotid artery images (<50%) versus normal with a sensitivity of 92%, specificity of 87% and an accuracy of 94%. This value (sensitivity, specificity and accuracy) for group of 50-75% stenosis versus normal was 84%, 80% and 88% and for carotid artery disease of more than 75% was 90%, 83% and 92%, respectively. CONCLUSION: This study demonstrates the feasibility, applicability and accuracy of artificial intelligence in the detection of carotid artery disease in greyscale static DUS images. This network has the potential to be used as a stand-alone software or to be embedded in any DUS machine. This can enhance carotid artery disease recognition with limited or no vascular experience or serve as a stratification tool for tertiary referral, further imaging and overall management.

Impact of stent compression in patients with non-thrombotic iliac vein lesions on iliac vein blood flow and related symptoms.

OBJECTIVES: To study outcomes in patients with non-thrombotic iliac vein lesions (NIVLs) treated by stents. METHODS: We performed a retrospective study that collected 109 patients from January 2016 to August 2020 diagnosed with symptomatic NIVLs. The patients underwent endovenous stenting using the Wallstents. Clinical severity was assessed using the venous clinical severity score and the Villalta scores. The patency was assessed using duplex ultrasound, while the diameters and the blood flow velocities (BFVs) in the proximal, middle, and distal stented segments were recorded simultaneously. RESULTS: A total of 128 stents were placed in 115 limbs (median age, 61 years), with a mean follow-up of 32 months. At 36 months, the Villalta scores went from 12.17 to 3.64 (p < .001). The VCSS went from 9.41 to 3.31 (p < .001). The mean diameters in the proximal, middle, and distal stented segments were 8.52 ± 2.15 mm, 10.13 ± 1.75 mm, and 10.17 ± 1.69 mm in the first month, while the mean BFVs were 31.17 ± 13.66 cm/s, 31.07 ± 11.90 cm/s, and 36.39 ± 18.41 cm/s, respectively. Repeated-measures analysis in 55 consecutive patients from 1 month to 3 years after procedure revealed a decrease of the stent diameter in the proximal stented segment (p = .004); a stabilization of the stent diameter in the middle (p = .43) or distal (p = .45) stented segment; a steadiness of the BFVs in the proximal (p = .40), middle (p = .93), and distal (p = .25) stented segments; and an improvement in the VCSS (p = .03) and Villalta scores (p = .006). CONCLUSIONS: BFVs in stented segments remained steady and the symptoms in lower extremities improved after surgery, while stent compression was observed in the diameter of the proximal stented segment, with no impact on BFVs or symptoms.

Critical analysis of vertebral artery flow patterns/subclavian steal detected by cerebrovascular duplex ultrasound examinations and its clinical implications.

BACKGROUND: The prevalence of subclavian steal (defined as retrograde/bidirectional vertebral artery flow) in the general population and in patients undergoing cerebrovascular duplex ultrasound (CDUS) examinations is variable. This is the largest study to date to analyze the incidence of duplex-suggested subclavian steal in 5615 CDUS examinations over a 1-year period and to examine its clinical implications. PATIENT POPULATION AND METHODS: All consecutive CDUS examinations performed over a 1-year period were analyzed for the presence of subclavian steal. Indications of testing, presence of posterior cerebral circulation/subclavian steal symptoms, and any interventions for subclavian steal were analyzed. RESULTS: A total of 171 of 5615 (3.1%) CDUS examinations were found to have subclavian steal (duplex-suggested). One hundred seventeen (2.1%) had retrograde flow and 54 (1%) had bidirectional flow. Of 171, 104 (60.8%) were left sided. Indications for CDUS were post-carotid endarterectomy/carotid artery stenting surveillance in 39 patients (22.8%), surveillance for progression of carotid stenosis in 76 patients (44.4%), transient ischemic attack/stroke in 26 patients (15%), asymptomatic screening/carotid bruit in 18 patients (10.5%), and isolated posterior cerebral circulation symptoms in 12 patients (7%). A total of 63% patients had associated >50% carotid stenosis. The mean arm Doppler pressure gradient was 32.2 mm Hg for asymptomatic patients vs 37 mm Hg for patients with posterior circulation symptoms (P = .3254). There were significant differences between the mean systolic arm pressure for patients with retrograde vs antegrade vs bidirectional flow (105 mm Hg vs 146 mm Hg vs 134 mm Hg, respectively, P < .0001). All patients with retrograde flow had >50% subclavian stenosis or occlusion (100 of 117 had subtotal/total occlusion) except for one patient. Meanwhile, 52 of 54 patients with bidirectional flow had >50% subclavian stenosis (6 of 54 with subtotal/total occlusion), whereas two patients were normal/<50% stenosis (P < .0001). Overall, 26 of 171 patients (15.2%) had interventions for disabling symptoms. Eleven of 26 of all interventions were for disabling arm claudication, and only 10 of 171 patients (5.8%) were intervened for disabling posterior circulation symptoms with complete resolution of symptoms in all except one. At a late follow-up with a mean of 18 months (range: 1-37 months), there was no late major stroke with only two lacunar infarcts (not subclavian steal related). There were also seven late deaths, none stroke related. CONCLUSIONS: The incidence of subclavian steal in patients who undergo CDUS is relatively rare. Most of these patients are asymptomatic and can be treated conservatively, and only a few may need intervention for disabling symptoms with good symptom resolution.

Duplex ultrasound and clinical outcomes of medical management of pediatric lower extremity arterial thrombosis.

OBJECTIVES: Natural history and duplex ultrasound (DU) findings of pediatric lower extremity arterial thrombosis (PLEAT) are not well-defined. We describe acute and short-term DU findings of PLEAT to aid duplex interpretation and patient management. METHODS: From August 2018 to April 2021 children with suspected PLEAT were identified prospectively. All had DU studies and were divided into group 1 (with DU-confirmed PLEAT) and group 2 (without DU-confirmed PLEAT). Patient demographics and DU findings were compared. Those with PLEAT and follow-up DU studies were also evaluated for recanalization and post recanalization DU findings. RESULTS: We included 76 children (102 limbs) who had suspected PLEAT; 32 in group 1 and 44 group in 2. Fifty-seven percent had congenital heart disease, 26% a history prematurity (87%, 34% group 1; 11%, 14% group 2), with 14% of group 1 premature at PLEAT diagnosis and 68% aged less than 3 years-29 (94%) in group 1 and 23 (52%) in group 2. None had an arterial procedure to restore flow. Limb salvage was 100% with five group 1 mortalities unrelated to PLEAT. In group 1, 12 PLEATs were associated with an arterial line and 15 with cardiac catheterization. Occluded arteries included 7 external iliac, 20 common femoral, and 5 superficial femoral arteries (SFA). Peak systolic velocities (PSVs) distal to occluded segments in group 1 were lower than corresponding group 2 PSVs. SFA 18 ± 21 cm/s vs 84 ± 39 cm/s; popliteal artery (PA) 24 ± 18 cm/s vs 78 ± 38 cm/s; posterior tibial artery (PTA) 10 ± 8 cm/s versus 49 ± 27 cm/s (all P < .001). Twenty-one patients in group 1 had follow-up studies. Twelve (57%) were recanalized: 4 (19%) in less than 1 week and 10 (48%) by 6 months. Eighty-one percent of PLEATs were treated with anticoagulation (AC) and 57% recanalized. Fifty-nine percent of patients on AC recanalized, and 60% not on AC recanalized. Age, primary diagnosis, instrumentation type, and AC were not associated with failure to recanalize. After recanalization, PSVs in the CFA were not different than PSVs found in group 2 in the CFA (109 ± 50 cm/s vs 107 ± 57 cm/s; P = .88), but remained decreased in the SFA, PA, and PTA (SFA 68 ± 32 cm/s vs 83 ± 38 cm/s [P = .04]; PA 33 ± 13 cm/s vs 78 ± 37 [P = .0004]; and PTA 21 ± 8 cm/s vs 43 ± 20 cm/s [P = .0008]). CONCLUSIONS: PLEAT occurs in young children, results in low distal PSVs, and often does not recanalize, but does not lead to short-term limb loss or mortality or necessarily require AC for recanalization. Normalization of CFA PSVs indicates recanalization while PSVs in segments distal to the CFA do not seem to return to normal.

Cost-effectiveness of computed tomography versus ultrasound-based surveillance following endovascular aortic repair of intact infrarenal abdominal aortic aneurysms.

BACKGROUND: While Society for Vascular Surgery guidelines recommend computed tomography angiography (CTA) or ultrasound for surveillance following infrarenal endovascular aortic repair (EVAR), there is a lack of consensus regarding optimal timing and modalities. We hypothesized that ultrasound-based approaches would be more cost-effective and developed a cost-effectiveness analysis to estimate the lifetime costs and outcomes of various strategies. METHODS: We developed a decision tree with nested Markov models to compare five surveillance strategies: yearly CTA, yearly CDU, yearly CEU, CTA at first year followed by CDU, and CTA at first year followed by CEU. The model accounted for differential sensitivity, specificity, and risk of acute kidney injury after CTA, and was implemented on a monthly cycle with a willingness-to-pay threshold of $50,000 per quality-adjusted life year (QALY) and 3% annual discounting. RESULTS: Under base case assumptions, the CTA-CDU strategy was cost effective with a lifetime cost of $77950 for 7.74 QALYs. In sensitivity analysis, the CTA-CDU approach remained cost-effective when CEU specificity was less than 95%, and risk of acute kidney injury following CTA was less than 20%. At diagnostic sensitivities below 75% for CEU and 55% for CDU, a yearly CTA strategy maximized QALYs. CONCLUSIONS: A hybrid strategy in which CTA is performed in the first year and CDU is performed annually thereafter is the most cost-effective strategy for infrarenal EVAR surveillance in patients with less than a 20% risk of contrast-induced nephropathy. If the sensitivity of CEU and CDU are at the lower end of plausible estimates, a yearly CTA strategy is reasonable. Further research should aim to identify patients who may benefit from alternative surveillance strategies.

Validation of a Standardised Duplex Ultrasound Classification System for the Reporting and Grading of Peripheral Arterial Disease.

OBJECTIVE: Duplex ultrasound (DUS), a non-invasive means of arterial mapping, allows for the reliable diagnosis of peripheral arterial disease (PAD). One of the authors (C.P.O.), developed a standardised DUS based scoring system, devised for rapid detection and reporting of PAD. The purpose of this study was to validate this system, and to determine the diagnostic performance both overall and per disease severity. METHODS: In total, 250 participants were recruited, based on diagnosis of (n = 125) or absence of PAD (n = 125) from general practice registers. Right and left legs per subject were handled as independent readings, determining actual PAD status via ankle brachial pressure index (ABPI) < 0.9, and then further grading disease severity using suggested ABPI ranges. Data were excluded if no corresponding ABPI value was obtained per DUS determination or if the ABPI reading was > 1.4, owing to the risk of false negatives due to incompressible vessels. Diagnostic sensitivity and specificity were obtained overall, and per severity classification. Furthermore, inter-rater agreement between ABPI and DUS determined PAD severity was determined by linear weighted Cohen's kappa. RESULTS: The sensitivity and specificity in the detection of disease overall was 81.0% (95% confidence interval [CI] 73.4 - 87.2) and 86.3% (95% CI 82.3 - 89.8), respectively. From mild to severe PAD, sensitivity increased from 71.1% (95% CI 55.7 - 83.6) to 89.3% (95% CI 71.8 - 97.7). Furthermore, a Cohen's kappa value of 0.63 (95% CI 0.57 - 0.69) was obtained, indicating moderate agreement between the two diagnostic methods. CONCLUSION: The findings of this study validate the diagnostic performance of the standardised DUS scoring system, as well as its capacity to grade severity of disease, offering a potential tool for the identification of PAD in community/research settings following initial screening methods. Confirmatory work could include a comparison of DUS determined disease with gold standard methods of non-invasive angiography, and novel tools such as toe flex near infrared spectroscopy and multisite photoplethysmography.

Surveillance for jugular venous thrombosis in astronauts.

BACKGROUND: Thrombosis of the left internal jugular vein in an astronaut aboard the International Space Station was recently described, incidentally discovered during a research study of blood flow in neck veins in microgravity. Given this event, and the high incidence of flow abnormalities, the National Aeronautics and Space Administration (NASA) instituted an occupational surveillance program to evaluate astronauts for venous thrombosis. METHODS: Duplex ultrasound of the bilateral internal jugular veins was conducted on all NASA astronauts terrestrially, and at three points during spaceflight. Respiratory maneuvers were performed. Images were analyzed for thrombosis and certain hemodynamic characteristics, including peak velocity and degree of echogenicity. RESULTS: Eleven astronauts were evaluated with matching terrestrial and in-flight ultrasounds. No thrombosis was detected. Compared to terrestrial ultrasound measurements, in-flight peak velocity was reduced and lowest in the left. Six of 11 astronauts had mild-moderate echogenicity in the left internal jugular vein during spaceflight, but none had more than mild echogenicity in the right internal jugular vein. Two astronauts developed retrograde blood flow in the left internal jugular vein. CONCLUSION: Abnormal flow characteristics in microgravity, most prominent in the left internal jugular vein, may signal an increased risk for thrombus formation in some individuals.

Manifestations of circulatory assist devices in noninvasive arterial duplex evaluation: A pictorial review.

Spectral Doppler and plethysmographic waveforms vary significantly in the presence of circulatory assist devices. Understanding the effect these devices have on the waveforms and flow characteristics is necessary for the appropriate interpretation of duplex ultrasound and other noninvasive vascular studies. We review the different arterial waveforms that can be seen with circulatory assist devices.

Machine learning-based classification of arterial spectral waveforms for the diagnosis of peripheral artery disease in the context of diabetes: A proof-of-concept study.

BACKGROUND: Point-of-care duplex ultrasound has emerged as a promising test for the diagnosis of peripheral artery disease (PAD). However, the interpretation of morphologically diverse Doppler arterial spectral waveforms is challenging and associated with wide inter-observer variation. The aim of this study is to evaluate the utility of machine learning techniques for the diagnosis of PAD from Doppler arterial spectral waveforms sampled at the level of the ankle in patients with diabetes. METHODS: In two centres, 590 Doppler arterial spectral waveform images (PAD 369, no-PAD 221) from 305 patients were prospectively collected. Doppler arterial spectral waveform signals were reconstructed. Blinded full lower-limb reference duplex ultrasound results were used to label waveform according to PAD status (i.e., PAD, no-PAD). Statistical metrics and multiscale wavelet variance were extracted as discriminatory features. A long short-term memory (LSTM) network was used for the classification of raw signals, and logistic regression (LR) and support vector machines (SVM) were used for classification of extracted features. Signals and feature vectors were randomly divided into training (80%) and testing (20%) sets. RESULTS: The highest overall accuracy was achieved using a logistic regression model with a combination of statistical and multiscale wavelet variance features, with 88% accuracy, 92% sensitivity, and 82% specificity. The area under the receiver operating characteristics curve (AUC) was 0.93. CONCLUSION: We have constructed a machine learning algorithm with high discriminatory ability for the diagnosis of PAD using Doppler arterial spectral waveforms sampled at the ankle vessels.

Popliteal cysts are not a risk factor for lower extremity deep vein thrombosis.

BACKGROUND: Popliteal cysts (PC) result from distension of the gastrocnemio-semimembranosous bursa. Published reports indicate coincident PC and deep vein thrombosis (DVT). Whether the presence of PC increase the risk of deep vein thrombosis (DVT) remains unclear. METHODS: Lower extremity venous Duplex ultrasound (DUS) reports were evaluated across the Mayo Clinic Enterprise (Rochester, Minnesota, Jacksonville, Florida, Scottsdale, Arizona, and the Mayo Clinic Health System) in patients ≥ 18 years of age. Natural language processing (NLP) algorithms were created and validated to identify acute lower extremity DVT and PC from these reports. To determine whether there is a link between PC and lower extremity DVT, the frequency of PC among cases (ultrasounds with acute DVT) were compared to controls (ultrasounds without acute DVT). RESULTS: A total of 357,703 lower extremities venous DUS were performed in 237,052 patients (mean age 63.3 ± 16.6, 54.4% were female) between 1992 and 2021. Acute DVT was identified in 32,572 (9.1%) DUS, and PC in 32,448 (9.1%). PC were seen in a lower frequency (8.0%) of ultrasounds with acute DVT than those without (9.2%) acute DVT (OR: 0.85, 95% CI: 0.82 to 0.89, p < 0.001). In a multivariate logistic regression model after adjusting for age, sex, and race, PCs were not positively associated with acute DVT (adjusted OR: 0.84, 95% CI: 0.81 to 0.88). CONCLUSIONS: PC are an incidental finding or an alternative diagnosis on lower extremity venous DUS, a finding that increases significantly with age. PC were not a risk factor in the development of lower extremity DVT.