Value of the duplex waveform at the common femoral artery for diagnosing obstructive aortoiliac disease

Can Common Femoral Artery Doppler Waveform Analysis Reliably Predict Hemodynamically Significant Disease of the Aortoiliac Arteries? A Systematic Review and Meta-Analysis

BACKGROUND

Many guidelines recommend duplex scanning as the first-line investigation for peripheral arterial disease. Qualitative evaluation of the common femoral artery (CFA) waveform provides information regarding the likely presence of significant aortoiliac disease. Certain centers use a "triphasic-and-down" policy, proceeding directly to antegrade endovascular intervention of infra-inguinal disease if the CFA waveform is triphasic. Others mandate cross-sectional imaging regardless of CFA waveform to exclude occult aortoiliac disease. This review aims to analyze the reliability of CFA waveform in excluding significant aortoiliac disease.

METHODS

MEDLINE, Embase, Cochrane library, and reference lists were searched for studies comparing CFA waveform analysis with reference tests assessing aortoiliac disease. Triphasic waveforms were considered "normal", while biphasic/monophasic were considered "abnormal." Meta-analyses using a bivariate model produced pooled diagnostic accuracy metrics, including negative and positive predictive values, sensitivity, and specificity.

RESULTS

Eight studies with 1,139 limbs were included. Where reported, the mean age was 67, 64.4% had claudication and 35.6% had critical limb ischemia, 42.3% were smokers, and 33.3% were diabetic. Reference investigations were catheter or cross-sectional angiography(n = 5), aortoiliac duplex(n = 2), and intra-arterial pressures(n = 1). The pooled negative predictive value was 84.7% (95% confidence interval [CI]: 59.3%-97.0%), meaning a triphasic waveform correctly excludes significant aortoiliac disease 84.7% of the time, and positive predictive value was 71.3% (95% CI: 36.1%-93.1%). Sensitivity was 0.86 (95% CI: 0.78-0.92), indicating 14% of patients with significant aortoiliac disease had triphasic waveforms, and specificity was 0.78 (95% CI: 0.61-0.89).

CONCLUSION

The best data available suggests Doppler waveform analysis lacks precision in identifying and excluding significant aortoiliac disease compared to heterogenous reference tests. A low threshold for cross-sectional imaging before antegrade endovascular intervention may be appropriate.

Nutcracker Syndrome Revealed by Hematuria in a Young Woman: A Case Report and Literature Review

Nutcracker syndrome is a rare condition that arises from the left renal vein getting compressed between the aorta and the superior mesenteric artery. Despite its clinical significance, this syndrome is often challenging to diagnose and is frequently overlooked. Its key clinical presentations include hematuria and pelvic or back pain. This condition involves elevated pressure on the left renal vein, leading to various signs and symptoms, with hematuria being a common manifestation. Herein, we report a 28-year-old woman with no medical history who presented with hematuria for two months. Abdominal CT revealed compression of the left renal vein between the superior mesenteric artery and abdominal aorta, with dilated left ovarian vein and pelvic varices, consistent with nutcracker syndrome.

Leriche syndrome: Clinical and diagnostic approach of a rare infrarenal aortoiliac occlusive disease

Leriche syndrome is an aortoiliac occlusive arterial disease comprising decreased peripheral pulses, claudication, and erectile dysfunction. We present a case of a 60-year-old male with abdominal pain and hematochezia who was diagnosed with hemorrhoids. The patient also had associated leg cramps on both sides and lower limb weakness. Further evaluation of the patient with imaging revealed occlusion of the distal descending abdominal aorta below the level of renal arteries and the iliac arteries. An incidental finding of Leriche syndrome was evident. This case report contributes to the current literature when any patient with abdominal pain and bilateral lower limb weakness, Leriche syndrome should be considered to avoid complications as it has high morbidity and mortality.

The Role of Ultrasound Examination in the Assessment of Suitability of Calcified Arteries for Vascular Access Creation-Mini Review

Arterial calcifications are present in 20-40% of patients with end-stage kidney disease and are more frequent among the elderly and diabetics. They reduce the possibility of arterio-venous fistula (AVF) formation and maturation and increase the likelihood of complications, especially distal ischemia. This review focuses on methods for detecting arterial calcifications and assessing the suitability of calcified arteries for providing inflow before the construction of an AVF. The importance of a clinical examination is stressed. A grading system is proposed for quantifying the severity of calcifications in the arteries of the arm with B-mode and Doppler ultrasound exams. Functional tests to assess the suitability of the artery to provide adequate inflow to the AVF are discussed, including Doppler indices (peak systolic velocity and resistive index during reactive hyperemia). Possible predictors of the development of distal ischemia are discussed (finger pressure, digital brachial index, acceleration and acceleration time), as well as the outcomes of AVFs placed on calcified arteries. It is concluded that a noninvasive ultrasound examination is probably the best tool for a morphologic and functional assessment of the arteries. An arterial assessment is of utmost importance if we are to create distal radiocephalic AVFs in our elderly patients whenever possible without burdening them with futile surgical attempts.

Phasicity and resistance of the arterial spectral Doppler waveform in a canine femoral focal artery stenosis model

INTRODUCTION

This study aims to evaluate changes in the arterial spectral Doppler waveform in a canine artery stenosis model.

METHODS

Canine femoral artery stenosis models were established in 12 beagle dogs. Doppler waveforms were recorded in the femoral artery preoperatively and postoperatively in the femoral artery and at the ankle after formation of a 50%, 70%, and 90% stenosis or occlusion. Major descriptors for arterial Doppler waveform were used to analyse waveforms.

RESULTS

The proportion of multiphasic waveforms proximal to a moderate stenosis decreased compared to normal baseline, although the difference was not statistically significant, whereas the decreases at the stenosis, distal to the stenosis, and at the ankle were significant (p < 0.05). The decreases in arteries with a more severe stenosis or occlusion were significant at all locations (p < 0.05). The proportion of high resistive waveforms decreased significantly at the ankle in the arteries with a moderate stenosis (50%) (p = 0.002), but the decreases proximal to, at, and distal to the stenosis were not significant. The decreases were significant at all locations in the arteries with a more severe stenosis (p < 0.05). The decrease was significant at the ankle in the arteries with an occlusion (p < 0.001) but not significant pre, at, and post an occlusion.

CONCLUSIONS

Phasicity and resistance of Doppler waveforms alter in canine femoral arteries with a stenosis. Phasicity change seems more sensitive in response to an arterial stenosis than resistance change. Additional information on arterial resistance could be obtained using end-diastolic ratios, resistive indices, and potentially end-systolic notch velocity measurements.

Artificial intelligence for the evaluation of peripheral artery disease using arterial Doppler waveforms to predict abnormal ankle-brachial index

BACKGROUND

Patients with peripheral artery disease (PAD) are at increased risk for major adverse limb and cardiac events including mortality. Developing screening tools capable of accurate PAD identification is a necessary first step for strategies of adverse outcome prevention. This study aimed to determine whether machine analysis of a resting Doppler waveform using deep neural networks can accurately identify patients with PAD.

METHODS

Consecutive patients (4/1/2015 - 12/31/2020) undergoing rest and postexercise ankle-brachial index (ABI) testing were included. Patients were randomly allocated to training, validation, and testing subsets (70%/15%/15%). Deep neural networks were trained on resting posterior tibial arterial Doppler waveforms to predict normal (> 0.9) or PAD (⩽ 0.9) using rest and postexercise ABI. A separate dataset of 151 patients who underwent testing during a period after the model had been created and validated (1/1/2021 - 3/31/2021) was used for secondary validation. Area under the receiver operating characteristic curves (AUC) were constructed to evaluate test performance.

RESULTS

Among 11,748 total patients, 3432 patients met study criteria: 1941 with PAD (mean age 69 ± 12 years) and 1491 without PAD (64 ± 14 years). The predictive model with highest performance identified PAD with an AUC 0.94 (CI = 0.92-0.96), sensitivity 0.83, specificity 0.88, accuracy 0.85, and positive predictive value (PPV) 0.90. Results were similar for the validation dataset: AUC 0.94 (CI = 0.91-0.98), sensitivity 0.91, specificity 0.85, accuracy 0.89, and PPV 0.89 (postexercise ABI comparison).

CONCLUSION

An artificial intelligence-enabled analysis of a resting Doppler arterial waveform permits identification of PAD at a clinically relevant performance level.

Management of chronic peripheral artery disease patients with indication for endovascular revascularization

With an increasing global burden of patients with chronic peripheral artery disease (PAD) the safe and effective provision of lower limb revascularisation is a growing medical need. Endovascular procedures for the treatment of PAD have become a crucial cornerstone of modern vascular medicine, and the first line revascularisation approach if technically feasible and taking patient choice into consideration. With the increasing age of patients with PAD and the increasing number of comorbidities open vascular surgery is also often not feasible. We outline a framework of key messages, endorsed by the board of the European Society of Vascular Medicine for pre-, peri- and post procedural management of patients requiring endovascular arterial procedures of the lower limbs. These key messages emphasize the important and increasing role of interventional vascular physicians.

Commentary: Demystifying Doppler – revisiting a vital diagnostic tool

Doppler is the most commonly utilised vascular assessment tool by podiatrists in Australia and the United Kingdom. Doppler is a key component of many international guidelines for vascular assessment. Used alongside pressure measurements such as ankle and toe-brachial indices, Doppler assists podiatrists to diagnose, triage and subsequently manage patients with peripheral arterial disease. This commentary aims to clarify the importance, technique, and interpretation of continuous wave handheld Doppler in podiatry practice. This commentary presents discussion on the equipment and optimal test conditions for use of Doppler, and guidance on the technique required in podiatry clinical practice. Furthermore, there is a focus on interpretation of the output from Doppler including both audio and visual output. There is in depth discussion about identifying pathology and integration into the clinical management plan.

Use of a Pre-Trained Neural Network for Automatic Classification of Arterial Doppler Flow Waveforms: A Proof of Concept

BACKGROUND

Arterial Doppler flow waveform analysis is a tool recommended for the management of lower extremity peripheral arterial disease (PAD). To standardize the waveform analysis, classifications have been proposed. Neural networks have shown a great ability to categorize data. The aim of the present study was to use an existing neural network to evaluate the potential for categorization of arterial Doppler flow waveforms according to a commonly used classification.

METHODS

The Pareto efficient ResNet-101 (ResNet-101) neural network was chosen to categorize 424 images of arterial Doppler flow waveforms according to the Simplified Saint-Bonnet classification. As a reference, the inter-operator variability between two trained vascular medicine physicians was also assessed. Accuracy was expressed in percentage, and agreement was assessed using Cohen's Kappa coefficient.

RESULTS

After retraining, ResNet-101 was able to categorize waveforms with 83.7 ± 4.6% accuracy resulting in a kappa coefficient of 0.79 (0.75-0.83) (CI 95%), compared with a kappa coefficient of 0.83 (0.79-0.87) (CI 95%) between the two physicians.

CONCLUSION

This study suggests that the use of transfer learning on a pre-trained neural network is feasible for the automatic classification of images of arterial Doppler flow waveforms.

Inter-rater Reliability of a 13-Category Arterial Doppler Waveform Classification and Practice of French Vascular Physicians

Background: Arterial Doppler Ultrasound waveform (DW) analysis allows the detection and evaluation of lower extremity peripheral artery disease. The high heterogeneity of the reported description of DW is reduced by the use of classification. However, the reliability of these classifications is either unknown or low to moderate and practices of vascular caregivers regarding the use of these classifications remain unknown. Aims: This study aims to assess the inter-observer reliability of the Saint-Bonnet classification, a 13-category DW classification. The secondary objective was to determine the utilization rate of the most common classifications and the ability of these classifications to describe DW. Methods: A national survey was conducted among all vascular physicians of French society of vascular medicine. They were invited by email to describe on a website 20 DW without and with the display of the Saint-Bonnet classification. The reliability of this classification was estimated by Fleiss' Kappa expressed with [95% confidence interval]. A semantic analysis allowed us to classify the physicians' responses according to the terms used. Finally we have evaluated for each classification the rate of misuse, i.e., the addition of a complementary term to the defined categories. Results: One hundred and ten physicians participated and only 5% of these were familiar with Saint-Bonnet classification. Fifty-four percent of vascular physicians used no classification at all. Vascular physicians used the Spronk (four-category), Descotes (five-category) and Saint-Bonnet (13-category) classifications for respectively, 31, 10, and 5%. Kappa coefficient of Fleiss (κ) was 0.546 [0.544-0.547] (p < 0.001). Reliability by category ranges from κ of 0.075 to 0.864. In multivariate analysis, the use of a classification was associated with fewer years of experience and was dependent on geographic location. Misuse rate by classification was 88, 82, and 5% using Spronk, Descotes and Saint-Bonnet classifications respectively. Conclusion: The reliability of Saint-Bonnet classification is weak to moderate by vascular physicians who are not familiar with its use. However, unlike the other classifications, it seems to be sufficiently precise so that the user does not need to complete its description. There is a significant heterogeneity in the use of arterial Doppler classifications in France.

Arterial Doppler Waveforms Are Independently Associated With Maximal Walking Distance in Suspected Peripheral Artery Disease Patients

Objective: Arterial Doppler waveform recordings are commonly used to assess lower extremity arterial disease (LEAD) severity. However, little is known about the relationship between arterial Doppler waveform profiles and patients' walking capacity. The purpose of this study was to assess whether arterial Doppler waveforms are independently associated with maximal walking distance (MWD) in patients experiencing exertional limb symptoms. Materials and Methods: This cross-sectional study included suspected LEAD patients experiencing exertional limb symptoms. In both lower extremities, arterial Doppler waveforms and ankle-brachial index (ABI) values were obtained from the pedis and tibial posterior arteries. Each arterial flow measurement was ranked using the Saint-Bonnet classification system. Treadmill stress testing (3.2 km/h, 10% slope) coupled with exercise oximetry (Exercise-TcPO2) were used to determine MWD. Delta from rest oxygen pressure (DROP) was calculated. Following treadmill stress testing, post-exercise ABI values were recorded. Univariate and multivariate analyses were used to determine the clinical variables associated with MWD. Results: 186 patients experiencing exertional limb symptoms (62 ± 12 years and 26.8 ± 4.5 kg/m2) were included between May 2016 and June 2019. Median [25th; 75th] treadmill MWD was 235 [125;500]m. Better arterial Doppler waveforms were associated with better walking distance (p = 0.0012). Whereas, median MWD was 524 [185;525]m in the group that yielded the best Doppler waveforms, it was 182 [125,305]m in the group with the poorest Doppler waveforms (p = 0.0012). MWD was significantly better (p = 0.006) in the patients with the best ABIs. However, arterial Doppler waveforms alone were significantly associated with MWD (p = 0.0009) in the multivariate model. When exercise variables (post-exercise ABI or DROP) were incorporated into the multivariate model, these were the only variables to be associated with MWD. Conclusion: Of the various clinical parameters at rest, Doppler flow waveform profiles were associated with MWD in suspected LEAD patients. A stronger link was however found between exercise variables and MWD.

Comparison of the Use of Arterial Doppler Waveform Classifications in Clinical Routine to Describe Lower Limb Flow

BACKGROUND

Characterisation of arterial Doppler waveforms is a persistent problem and a source of confusion in clinical practice. Classifications have been proposed to address the problem but their efficacy in clinical practice is unknown. The aim of the present study was to compare the efficacy of the categorisation rate of Descotes and Cathignol, Spronk et al. and the simplified Saint-Bonnet classifications.

METHODS

This is a multicentre prospective study where 130 patients attending a vascular arterial ultrasound were enrolled and Doppler waveform acquisition was performed at the common femoral, the popliteal, and the distal arteries at both sides. Experienced vascular specialists categorized these waveforms according to the three classifications.

RESULTS

of 1033 Doppler waveforms, 793 (76.8%), 943 (91.3%) and 1014 (98.2%) waveforms could be categorized using Descotes and Cathignol, Spronk et al. and the simplified Saint-Bonnet classifications, respectively. Differences in categorisation between classifications were significant (Chi squared test, p < 0.0001). Of 19 waveforms uncategorized using the simplified Saint-Bonnet classification, 58% and 84% were not categorized using the Spronk et al. and Descotes and Cathignol classifications, respectively.

CONCLUSIONS

The results of the present study suggest that the simplified Saint-Bonnet classification provides a superior categorisation rate when compared with Spronk et al. and Descotes and Cathignol classifications.

Inter-rater Reliability of 4-Item Arterial Doppler Waveform Classification System for Description of Arterial Doppler Waveforms

Background: Non-invasive Doppler waveform (DW) analysis is a widely adopted method for detecting and evaluating lower extremity peripheral artery disease (PAD). Previous investigations have reported that broad heterogeneity in the description of Doppler waveforms is reduced by using a classification method. The reliability of arterial Doppler classification, however, is unknown.

Purpose: The purpose of this study is to assess the reliability of a 4-category arterial DW classification method among Chinese sonographers.

Methods: During a national ultrasound conference in China attendees were invited to classify thirty arterial Doppler waveforms. After viewing a 4-category (triphasic, biphasic, monophasic, and other) arterial Doppler waveform descriptor presentation, attendees were asked to classify 15 continuous wave (CW) and 15 pulsed wave (PW) Doppler waveforms. Their responses were recorded via mobile phone and the reliability of this 4-category classification was estimated by Fleiss' Kappa inter-rater statistical analysis.

Results: One hundred and seventy-eight attendees participated in the analysis. The Kappa coefficient of Fleiss (κ) for all attendees was 0.522 (p < 0.005) with 95% confidence interval (CI): 0.520–0.523. The reliability of the waveform descriptor triphasic was the highest (κ = 0.621, p < 0.005), and other was the lowest (κ = 0.341, p < 0.005).

Conclusion: The inter-rater reliability of a 4-category arterial Doppler waveform classification by Chinese sonographers is considered weak (κ = 0.522, CI95%: 0.520–0.523, p < 0.005). This study reinforces the importance of assessing DW classification reliability and the development of DW descriptors that are more accurately predictive of clinical hemodynamic events.

Novel Evaluation Method for Lower Extremity Peripheral Artery Disease With Duplex Ultrasound - Usefulness of Acceleration Time

BACKGROUND

Duplex ultrasound scanning (DUS) plays a major role in less invasive diagnosis and assessment of lesion severity in lower extremity peripheral artery disease (PAD). In this study, we evaluated the efficacy of each DUS parameter measured in patients with PAD and established a simple method for PAD evaluation.

METHODS AND RESULTS

We retrospectively investigated 211 patients (270 limbs) who underwent assessment with both angiography and DUS. During DUS of the common femoral artery (CFA) and popliteal artery, we measured 3 parameters: acceleration time (AcT), peak systolic velocity (PSV), and waveform contour. We compared these parameters with the degree of angiographic stenosis. AcT at the CFA had a significantly higher value in prediction of aortoiliac artery lesions with >50% stenosis (c-index, 0.85; 95% confidence interval (CI), 0.79-0.91), with a sensitivity of 0.82 and specificity of 0.76 at the best cutoff point, compared with PSV and waveform contour (P<0.001, respectively). For femoropopliteal lesions, the ratio of AcT at the popliteal artery to AcT at the CFA is the most predictive parameter, with sensitivity of 0.86 and specificity of 0.92 at the best cutoff point (c-index, 0.93; 95% CI, 0.90-0.97), compared with others (P<0.001, respectively).

CONCLUSIONS

For the assessment of PAD with DUS, AcT and AcT ratio are simple and reliable parameters for evaluating aortoiliac and femoropopliteal artery disease.

Interpretation of peripheral arterial and venous Doppler waveforms: A consensus statement from the Society for Vascular Medicine and Society for Vascular Ultrasound

This expert consensus statement on the interpretation of peripheral arterial and venous spectral Doppler waveforms was jointly commissioned by the Society for Vascular Medicine (SVM) and the Society for Vascular Ultrasound (SVU). The consensus statement proposes a standardized nomenclature for arterial and venous spectral Doppler waveforms using a framework of key major descriptors and additional modifier terms. These key major descriptors and additional modifier terms are presented alongside representative Doppler waveforms, and nomenclature tables provide context by listing previous alternate terms to be replaced by the new major descriptors and modifiers. Finally, the document reviews Doppler waveform alterations with physiologic changes and disease states, provides optimization techniques for waveform acquisition and display, and provides practical guidance for incorporating the proposed nomenclature into the final interpretation report.

Vascular Tests for Dermatologists

Dermatologists encounter patients with a variety of lower extremity ulcers including those related to venous insufficiency and peripheral arterial disease. Vascular studies, including ankle brachial pressure index, toe pressure, toe brachial index, Doppler arterial waveform, Duplex ultrasonography, and angiography, play an essential role in the prevention, diagnosis, and management of vascular diseases. In fact, dermatologists are often the first medical providers to see patients with complex vascular conditions. Knowledge of the appropriate indications, interpretations, limitations, and advantages of the various vascular studies is critical to the successful and swift management of each patient presenting with a lower extremity ulcer. This study reviews the most commonly ordered arterial and venous studies and discusses the appropriate indications and interpretation of these studies.

Modeling of a fast-response magnetic-sensitive hydrogel for dynamic control of microfluidic flow

A magnetic-sensitive hydrogel-based microfluidic system is designed via a magneto-chemo-hydro-mechanical model for replicating various physiological and pathological conditions in the human body, by which the desired flow patterns can be generated in real time due to the fast-response deformation of the magnetic hydrogel. In the model, the fluid-structure interaction is characterized between the deformable magnetic hydrogel and surrounding fluid flow through the fully coupled arbitrary Lagrangian-Eulerian (ALE) method. Moreover, the physicochemical mechanisms including hydrogel magnetization, fluid diffusion, fluid flow, and hydrogel large deformation are characterized. After validation of the present model with both the finite difference and experimental results in the open literature, the transient behavior of the magnetic hydrogel is investigated, and the results show that the response time for the magnetic hydrogel is improved significantly in a uniform magnetic field compared with that of a hydrogel without the magnetic effect. Furthermore, various patterns of pulsatile flow are generated for mimicking the cell physiological microenvironment experienced by bone marrow stromal cells, and also for the pathological condition at the femoral artery during diastole and systole, respectively. Therefore, the present magnetic-sensitive hydrogel-based microfluidic system via the multiphysics model may provide a relevant humanized manipulation platform to investigate cell behavior and function through microfluidic chips.

Heterogeneity of Doppler waveform description is decreased with the use of a dedicated classification

BACKGROUND

The analysis of Doppler ultrasound waveforms (DW) provides a method for detecting and evaluating arterial stenosis in the lower limb arteries but no recommendation exists on how to describe the DWs. Aims of this study were to assess the heterogeneity of the description of DWs among vascular residents and the impact of the use of a 4-item classification.

METHODS

Thirty different DWs were presented to residents using Microsoft PowerPoint^® slides. They were invited to describe the 30 DWs before and after the presentation of a 4-item classification (triphasic, biphasic, monophasic, and others). The heterogeneity was assessed by the number of different answers used by the residents. Nineteen residents with six to eighteen months of vascular medicine training and ultrasound experience were included.

RESULTS

The average of different answers was 9 ± 4 for the whole analysis of the 30 DWs without the use of a specific classification, whereas the average was 2 ± 1 using the 4-item classification (p < 0.005). There was a significant difference in correct answers, i. e. in combined continuous waveforms and pulsed waveforms between experienced residents and younger residents (p < 0.05).

CONCLUSIONS

Using a 4-item classification for DWs reduced the heterogeneity of the DW description. There is an urgent need to standardize the DW description in order to improve the patients care with peripheral artery disease.

Effectiveness of a multicenter training programme to teach point-of-care vascular ultrasound for the detection of peripheral arterial disease in people with diabetes

Background

The primary aim of this study was to evaluate the effectiveness of a training programme to teach a focused bedside ultrasound scan (PAD-scan; Podiatry Ankle Duplex Scan) for the detection of arterial disease in people with diabetes.

Methods

Five podiatrists and one diabetologist across two hospitals were enrolled in a structured training programme consisting of a training course (1-day), supervised scanning (5-weeks), independent scanning (3-weeks) and a final evaluation of performance (1-day).

Time, technical skills (Duplex Ultrasound Objective Structured Assessment of Technical Skills tool (DUOSATS); minimum score = 6, maximum score = 26) and accuracy (level of agreement with vascular scientist PAD-scan assessment) were assessed for every supervised scan and again for the final evaluation of performance.

Results

A total of 90 PAD-scans in 65 patients were performed during the supervised phase. Participants demonstrated significant improvements in median time (19 min(IQR 13.9–25.5) vs 9.3 min (IQR 7.3–10.5);p = 0.028) and DUOSATS scores (17.5 (IQR 16.8–21) vs 25 (IQR 24–25.3); p = 0.027). At the final evaluation, participants completed scans in 5.4 min (IQR 5.3–5.9), achieved full DUOSAT scores and perfect agreement with the vascular scientist.

Conclusion

A structured training programme, integrated into diabetic foot clinics, was effective in teaching the PAD-scan

Electronic supplementary material

The online version of this article (10.1186/s13047-018-0283-0) contains supplementary material, which is available to authorized users.

A novel computer-aided diagnostic approach for detecting peripheral arterial disease in patients with diabetes

Peripheral arterial disease (PAD) is an important manifestation of systemic atherosclerosis, with diabetes being one of its most significant risk factors. Owing to medial arterial calcification (MAC), the ankle–brachial index (ABI) is not always a reliable tool for detecting PAD. Arterial Doppler flow parameters, such as systolic maximal acceleration (ACCmax) and relative pulse slope index (RPSI), may serve as effective surrogates to detect stenosis-induced flow alteration. In the present study, ACCmax and RPSI were prospectively evaluated in 166 patients (304 arteries) with clinical suspicion of PAD, including 76 patients with and 90 patients without diabetes. In the overall sample, the sensitivity of ACCmax (69%) was superior to that of ABI (58%) and RPSI (56%). In patients with diabetes, the sensitivity of ACCmax (57%), ABI (56%) and RPSI (57%) were similar, though a parallel test taking both ACCmax and RPSI into account further increased sensitivity to 68%. The specificity (98%) and accuracy (78%) of ACCmax were superior to those of ABI (83% and 70%, respectively), as were the specificity (95%) and accuracy (77%) of RPSI in patients with diabetes. The diagnostic properties of ACCmax and RPSI were superior to those of ABI for detecting PAD in patients with diabetes. Our acceleration algorithm (Gefäßtachometer^®) provides a rapid, safe, noninvasive tool for identifying PAD in patients with diabetes.

[College of the French Vascular Medicine Teachers (CEMV) statement: Arterial Doppler waveforms analysis (simplified Saint-Bonnet classification)]

Lower extremity peripheral artery disease is a frequent disease. Arterial Doppler waveforms analysis is a key element in vascular medicine, especially to diagnose lower peripheral artery disease. Although Doppler waveforms are often used, descriptions are highly heterogeneous. This review presents the simplified Saint-Bonnet classification that is tought to vascular medicine residents in order to homogenize arterial flow description.

Transduction of Repetitive Mechanical Stimuli by Piezo1 and Piezo2 Ion Channels

Several cell types experience repetitive mechanical stimuli, including vein endothelial cells during pulsating blood flow, inner ear hair cells upon sound exposure, and skin cells and their innervating dorsal root ganglion (DRG) neurons when sweeping across a textured surface or touching a vibrating object. While mechanosensitive Piezo ion channels have been clearly implicated in sensing static touch, their roles in transducing repetitive stimulations are less clear. Here, we perform electrophysiological recordings of heterologously expressed mouse Piezo1 and Piezo2 responding to repetitive mechanical stimulations. We find that both channels function as pronounced frequency filters whose transduction efficiencies vary with stimulus frequency, waveform, and duration. We then use numerical simulations and human disease-related point mutations to demonstrate that channel inactivation is the molecular mechanism underlying frequency filtering and further show that frequency filtering is conserved in rapidly adapting mouse DRG neurons. Our results give insight into the potential contributions of Piezos in transducing repetitive mechanical stimuli.

Discrepancies in Prevalence of Peripheral Arterial Disease between Lower Extremities at Rest and Postexercise

Background  Lower extremity peripheral arterial disease (PAD) is a common medical condition causing substantial morbidity. Limited data exist on whether discrepancies in PAD prevalence exist between the lower extremities using resting ankle-brachial indices (ABIs) and postexercise pressures. Objective  We predicted the prevalence of PAD between the lower extremities. Methods and Results  Consecutive patients who had undergone a noninvasive arterial lower extremity study at Mayo Clinic, Rochester, MN, between January 1996 and December 2012 with suspected PAD were retrospectively reviewed. We identified 12,312 consecutive patients who underwent an arterial lower extremity and an exercise treadmill study. Prevalence of PAD was assessed at rest and after exercise using two criteria: a resting ABI ≤ 0.90 and a postexercise pressure decrease of > 30 mm Hg. Mean age was 67 ± 12 years and there were 4,780 (39%) women studied. At rest, we found a higher prevalence of PAD on the left extremity (27.4%) compared with the right (24.6%) ( p  < 0.0001). After exercise, we found a higher prevalence of PAD on the right extremity (25.1%) compared with the left (19.0%) ( p  < 0.0001). These discrepancies between the prevalence of PAD at rest and after exercise were present in women and men. Conclusion  Using validated criteria of a resting ABI of ≤ 0.90 and postexercise ankle pressure decrease > 30 mm Hg, our results suggest that there is a significantly higher prevalence of PAD in the left lower extremity at rest, in contrast to a greater prevalence of abnormal postexercise testing in the right lower extremity. The reason(s) of these discrepancies remain to be studied.

Spectral analysis of femoral artery blood flow waveforms of conscious domestic cats

The qualitative and quantitative aspects of femoral artery blood flow waveform spectra were evaluated in 15 male and 15 female Persian and mixed breed domestic cats (Felis catus), which were healthy and not sedated, using duplex Doppler ultrasonography (DDU). Spectral Doppler demonstrated a biphasic characteristic in 16 (53.34%) of the animals evaluated, and a triphasic characteristic in the 14 (46.66%) remaining animals. The systolic blood pressure and heart rate values were within the normal range for the species. The quantitative parameters evaluated, based on the spectral Doppler, were as follows: systolic velocity peak (SVP), recent diastolic velocity peak (RDVP), end diastolic velocity peak (EDVP), mean velocity (MV), integral velocity time (ITV), artery diameter (AD), femoral flow volume (FFV), pulsatility index (PI), resistive index (RI), systolic peak acceleration time (AT) and deceleration time (DT). The respective mean values were: 36.41 ± 7.33 cm/s, 4.69 ± 0.90 cm/s, 10.74 ± 2.74 cm/s, 23.06 ± 4.86 cm/s, 3.91 ± 1.05 cm, 0.17 ± 0.04 cm, 0.11 ± 0.08 cm(3), 3.85 ± 0.19, 1.40 ± 0.20, 39.84 ± 7.38 ms, and 114.0 ± 22.15 ms. No significant differences were found between males and females. The analyses carried out on the femoral artery flow spectrum obtained by DDU showed that it is easy to use and highly tolerated in non-sedated, healthy cats. It appears that DDU may be a useful diagnostic technique, but further studies are needed to evaluate how it compares with invasive telemetric methodology or high-definition oscillometric waveform analytic techniques.

Triphasic umbilical artery waveform: association with severe fetal growth restriction, fetal demise, and extreme velamentous cord insertion

Extreme Doppler abnormalities of the umbilical artery such as absent or reversed end diastolic velocity are associated with adverse perinatal outcomes. We present a case of a triphasic umbilical artery waveform identified at 24 weeks. The fetus was severely growth restricted with an estimated fetal weight of 314 g. A week later, fetal demise occurred. Placental pathology revealed a placental weight of 83 g, an extensive maternal floor infarction, and an extreme velamentous cord insertion 7 cm from the edge of the placental disc, with vessels entering at opposite poles of the placental disc and a single anastomotic bridging vessel on the chorionic plate connecting these two vascular poles. A triphasic umbilical artery waveform may be associated with a premorbid state and severe placental vascular abnormality. We hypothesize that the third and positive component in late diastole is present due to forward flow across the communicating bridging vessel into the contralateral entering vessel.

Magnetoactive sponges for dynamic control of microfluidic flow patterns in microphysiological systems

We developed a microfluidic flow-control system capable of dynamically generating various flow patterns on demand. The flow-control system is based on novel magnetoactive sponges embedded in microfluidic flow channels. Applying a non-uniform magnetic field compresses the magnetoactive sponge, significantly reducing porosity and hydraulic conductivity. Tuning the applied magnetic field can dynamically vary the flow rate in the microfluidic channel. Pulsatile and physiological flow patterns with frequency between 1 and 3 Hz, flow rates between 0.5 and 10 μL min(-1) and duration over 3 weeks have been achieved. Smooth muscle cells in engineered blood vessels perfused for 7 days aligned perpendicular to the flow direction under pulsatile but not steady flow, similar to the in vivo orientation. Owing to its various advantages over traditional flow-control methods, the new system potentially has important applications in microfluidic-based microphysiological systems to simulate the physiological nature of blood flow.

The value of Doppler waveform analysis in predicting major lower extremity amputation among dialysis patients treated for diabetic foot ulcers

AIMS

This study examined the predictors for lower extremity amputation (LEA) in patients with diabetic foot ulcers according to kidney function and, in the case of dialysis patients, specifically evaluated the vasculature with the ankle-brachial index (ABI) and Doppler waveforms.

METHODS

Among 658 diabetic patients admitted to the Diabetic Foot Care Center, 286 had an estimated glomerular filtration rate (eGFR)≥ 60 ml/min per 1.73 m(2), 275 had an eGFR<60, and 97 patients were under maintenance dialysis. All clinical variables were analyzed. A specialist retrospectively reviewed Doppler images of 78 of the patients in dialysis to evaluate peripheral arterial disease.

RESULTS

Forty-two percent of patients with eGFR<60 presented with ABI≤0.90. For ABI values>1.40, the proportion of dialysis patients (31.3%) was greater than the proportion of patients with eGFR<60 (5.3%). Wagner wound classifications, reduced serum albumin levels, and low ABI values were the predictors for major LEA among patients in the non-dialysis groups. Nevertheless, these indicators were not predictive of the risk of amputation in diabetic patients on dialysis. The presence of poor monophasic waveforms in the dorsalis pedis artery or posterior tibial artery served as an independent predictor (odds ratio: 7.61; P=0.008) for major LEA among dialysis patients. The sensitivity and specificity were 88.0% and 59.6%, respectively.

CONCLUSIONS

Poor monophasic Doppler waveforms of below-the-knee arteries, commonly found among dialysis patients in treatment for diabetic foot ulcers, can serve as an independent predictor for major LEA.

Traditional Peripheral Arterial Doppler Waveform Descriptors

Traditional peripheral arterial waveforms have been inconsistently defined and classified. This investigation compares waveform categorization scores from two comparable groups of sonography participants. Group 1 interpreted continuous-wave (CW) and pulsed-wave (PW) Doppler waveforms based on standard text definitions. Group 2 performed the same task following 10 minutes of detailed waveform characterization instructions with accompanying illustrations. Each group comprised 157 participants with an equal number of students, registered sonographers, and physicians. Significant differences were noted between groups 1 and 2 for 60% of CW waveforms and 33% of PW waveforms ( P < .05). In group 2, American Registry for Diagnostic Sonography (ARDMS)–registered sonographers had significantly higher CW scores than students and physicians ( P < .0001); registered vascular technologists and multispecialty ARDMS-certified sonographers had significantly higher PW scores than students, Registered Diagnostic Medical Sonographer (RDMS)–certified sonographers, and physicians ( P = .0086 and P = .0295, respectively). This study emphasizes the contribution of sonographers in arterial Doppler waveform categorization and underscores the need for standardization and education.

Echocardiographic evaluation of aorto-iliac occlusive disease

Several studies demonstrated feasibility of visual assessment of the common femoral artery Doppler waveform, in an indirect evaluation of aorto-iliac segment stenosis. Patients with cardiac diseases referred for echocardiography often have coexistent arterial pathology. Since many of them are potential candidates for endovascular procedures, we decided to study, whether echocardiography can be useful for detection of aorto-iliac occlusive disease. We evaluated 92 patients with abdominal aortic aneurysm or peripheral artery occlusive disease, referred from the vascular surgery department for cardiac evaluation before surgery. At the end of an echocardiographic examination, evaluation of flow in the distal external iliac arteries with an echocardiographic probe was performed. The Doppler waveform was classified into normal—with early diastolic flow reversal or abnormal—without early diastolic flow reversal. Echocardiographic results were compared in a blinded fashion with reports from computed tomography angiography. Overall there were 58 iliac segments with significant (≥70%) area stenosis or occlusion and 126 iliac segments without significant disease on computed tomography angiography. Abnormal Doppler waveform was found in 56 out of 58 abnormal iliac segments—sensitivity 97%, and normal waveform was found in 106 out of 126 normal iliac segments—specificity 84%. Positive predictive value of abnormal Doppler waveform for significant iliac disease was 74%, and negative predicting value was 98%. Detection of significant stenoses in aorto-iliac segments is feasible with echocardiography. Further studies are necessary to evaluate its potential utility in a population of patients with cardiac disease referred for echocardiographic study.

Do Doppler waveforms at the common femoral artery accurately predict iliac stenosis?

OBJECTIVE

Evaluate whether common femoral artery (CFA) Doppler waveform assessment predicted the presence of significant iliac artery stenosis as visualised on magnetic resonance angiography (MRA).

METHOD

Three-year retrospective study of patients investigated using CFA Doppler waveforms and MRA. The patients were identified from vascular/radiology databases. Waveforms were reported real time as monophasic, biphasic or triphasic. Results were compared with MRA findings.

RESULTS

In 76 patients, 119 waveforms were assessed. MRA demonstrated 37 iliac vessels with significant stenosis. 32 (86%) had abnormal waveforms (monophasic/biphasic), 5 were triphasic. In 82 cases where MRA showed no significant stenosis, waveforms were abnormal in 35 (43%). Abnormal CFA waveforms have sensitivity of 86% and specificity of 57%. Monophasic waveforms alone were more specific (88%) but less sensitive (57%) for predicting iliac lesions.

CONCLUSION

Whilst CFA waveform morphology is a useful adjunct in detection of iliac disease, normal triphasic waveforms do not exclude iliac stenosis.

Confusion of Peripheral Arterial Doppler Waveform Terminology

Characterization of peripheral arterial waveforms is basic to the diagnosis of vascular disease. Surveys indicate inconsistent application of traditional waveform descriptors. This study reviews literature to identify areas of confusion. Publications were reviewed to determine whether triphasic, biphasic, and monophasic terms were defined; if biphasic was linked with diastolic flow reversal; whether pandiastolic flow was associated with biphasic or monophasic terminology; and whether waveform illustrations had a zero baseline. Ninety-four publications were reviewed. Triphasic and monophasic were defined in 81%, biphasic in 48%. Biphasic was classified with flow reversal in 38%. Pandiastolic flow was not addressed in 57% but associated with monophasic in 47% and biphasic in 5%. Twenty-one percent of the publications had an illustration without a zero-flow baseline. This review suggests a lack of consensus when classifying arterial blood flow with traditional waveform descriptors. Waveform characterization inconsistencies are undermining comprehension of Doppler principles and may lead to inappropriate testing. A multisocietal consensus panel should accept responsibility for resolving this issue.

Análise espectral segmentar no seguimento de pacientes revascularizados

CONTEXTO: Pacientes tratados por revascularização arterial (enxertos e angioplastias) nos membros inferiores acometidos por doença arterial oclusiva periférica foram seguidos por até 2 anos pós-tratamento usando ultrassom vascular (análise espectral segmentar, AES). OBJETIVO: Demonstrar que a AES pode ser utilizada no seguimento dos pacientes tratados por doença arterial oclusiva periférica. MÉTODOS: As medidas de AES realizadas foram: velocidade sistólica de pico, índice de pulsatilidade e forma da onda de velocidade de fluxo. Essas foram comparadas em cada paciente no pré e pós-tratamento (com intervalos de 3 meses) para diagnóstico de perviedade. RESULTADOS: Medidas realizadas no pós-operatório nas artérias imediatamente distais aos segmentos tratados mostraram aumento consistente de velocidade sistólica de pico e índice de pulsatilidade com mudanças na forma da onda de velocidade de fluxo de unifásica para bi ou trifásica. A velocidade sistólica de pico e o índice de pulsatilidade aumentaram respectivamente em 92,26 e 98,2% (tratamentos no segmento aorto-ilíaco), em 112,83 e 62,39% (tratamentos no segmento fêmoro-poplíteo) e em 149,08 e 28,8% (tratamentos no segmento poplíteo-tibial). Tais mudanças nos padrões de velocidade de fluxo ocorreram em todos os pacientes e permaneceram quase inalteradas enquanto os tratamentos estivessem pérvios. Quando ocorria falência nos tratamentos (oclusões ou estenoses hemodinamicamente significantes), os parâmetros caíam a níveis similares aos de antes do tratamento. Se a falência do tratamento era corrigida por nova revascularização (enxerto ou angioplastia), os parâmetros de AES voltavam a se comportar como após o tratamento inicial. CONCLUSÃO: A AES pode ser usada no seguimento dos pacientes com revascularização dos membros devido a doença arterial oclusiva periférica, demonstrando tanto a perviedade quanto a falência do tratamento.

Kissing stents in the aortic bifurcation--a valid reconstruction for aorto-iliac occlusive disease

OBJECTIVE

To evaluate outcome and patency predicting factors of kissingstent treatment for aorto iliac occlusive disease (AIOD).

METHODS

Patients treated with kissingstents for AOID between 1995 and 2004 at a tertiary referral center were identified through local databases. Chart review and preoperative images were used for TASC and Fontaine classification. Follow-up consisted of clinical exams, ABI and/or duplex. Patency rates were estimated by Kaplan-Meier analysis, and Cox multivariate regression was used to determine factors associated with patency.

RESULTS

173 consecutive patients (46% male, mean 64 years) were identified. TASC distribution was: A 15%, B 34%, C 10%, D 41%. Mean follow-up was 36 months (range: 1-144). 30-day mortality was 1% (2 patients), and 1-year survival was 91% (157 patients). 2 patients underwent late, open conversion and 13 patients suffered minor puncture site complications. Primary, assisted primary and secondary patency was: 97%, 99% and 100%, and 83%, 90% and 95% at twelve and 36 months respectively. There was no significant difference in patency between the TASC groups. Patency was significantly worse for patients in Fontaine class III.

CONCLUSIONS

Aortoiliac kissing stents is a valid alternative to open repair for TASC A-D lesions. The procedure has low mortality and morbidity and good patency at 3 years.

Internal thoracic artery-caudal epigastric artery as a collateral pathway in a dog with aortic occlusion: a case report

Aortic occlusion is a rare vascular disorder in the dog. This report describes the clinical feature of an aged Boxer with complete occlusion of the abdominal aorta caused by an intraluminal thrombus. Angiography evidenced a collateral circulation, represented by the internal thoracic artery, the cranial epigastric artery and the caudal epigastric artery, providing adequate blood flow to the pelvis and pelvic limbs. This vascular network has only recently been recognised as one of the major collateral pathways for arterial blood supply to the pelvis and lower extremities in humans with chronic aorto-iliac occlusive disease (CAOD). Furthermore, a femoral artery Doppler waveform, characterised by low amplitude, a monophasic systolic wave with blunted parabolic flow profile and a small spectral window, peculiar to humans with CAOD, is documented for the first time in a dog with aortic occlusion.

Color and pulsed Doppler sonography for arterial bleeding detection

OBJECTIVE

Hemorrhage resulting from penetrating injuries in the extremities is the leading cause of preventable death in the modern battlefield. Development of methods for detection and localization of vascular bleeding is needed that could be applied emergently without special training outside the hospital setting. Our objective was to assess whether Doppler sonography can provide quantitative parameters that characterize the bleeding site in the extremities.

METHODS

Twenty-four rabbit femoral arteries (diameter of approximately 1 mm) were punctured transcutaneously with an 18-gauge needle. Doppler interrogations were performed at 5 locations in the injured vessels (site of injury, distal and proximal locations relative to the injury, and neck and tip of the bleeding jet).

RESULTS

Compared with the normal signals obtained before the vessel was punctured, pulsed Doppler observations of the injury site showed a statistically significant increase in the systolic and diastolic velocities (systolic: mean +/- SD, 30.1 +/- 12.5 cm/s [injury] versus 15.1 +/- 4.2 cm/s [normal]; diastolic: 17.8 +/- 6.5 cm/s [injury] versus 0.7 cm/s [normal]). Similar increases in velocities were observed at the neck of the bleeding jet, whereas the tip of the bleeding jet showed venouslike patterns. These patterns are unique only at the bleeding site. Color Doppler observations showed turbulence (in the form of checkered color patterns) localized at the injury site.

CONCLUSIONS

Our results indicate that both color and pulsed Doppler sonography can be used to accurately localize the site of injury, which may facilitate application of hemorrhage control therapies in battlefield situations.