Nephrotoxic Contrast Research Articles

INav-based, Automated Coronary Magnetic Resonance Angiography for the Detection of Coronary Artery Stenosis (iNav-AUTO CMRA)

BackgroundCoronary computed tomography angiography (CCTA) is recommended as the first line diagnostic imaging modality in low to intermediate risk individuals suspected of stable coronary artery disease (CAD). However, CCTA exposes patients to ionising radiation and potentially nephrotoxic contrast agents. Invasive coronary angiography (ICA) is the gold-standard investigation to guide coronary revascularisation strategy, however, invasive procedures incur an inherent risk to the patient. Coronary magnetic resonance angiography (Coronary MRA) avoids these issues. Nevertheless, clinical implementation is currently limited due to extended scanning durations, inconsistent image quality, and consequent lack of diagnostic accuracy. Several technical Coronary MRA innovations including advanced respiratory motion correction with 100% scan efficiency (no data rejection), fast image acquisition with motion-corrected undersampled image reconstruction and deep-learning (DL)-based automated planning have been implemented and now await clinical validation in multi-centre trials. MethodsThe objective of the iNav-AUTO CMRA prospective multi-centre study is to evaluate the diagnostic accuracy of a newly developed, state-of-the-art, standardised, and automated Coronary MRA framework compared to CCTA in 230 patients undergoing clinical investigation for CAD. The study protocol mandates the administration of oral beta-blockers to decrease heart rate to below 60bpm and the use of sublingual nitroglycerine spray to induce vasodilation. Additionally, the study incorporates the utilisation of standardised postprocessing with sliding-thin-slab multiplanar reformatting, in combination with evaluation of the source images, to optimize the visualisation of coronary artery stenosis. DiscussionIf proven effective, Coronary MRA could provide a non-invasive, needle-free, yet also clinically viable, alternative to CCTA. Trial RegistrationThis study is registered at clinicaltrials.gov (NCT05473117).

#1983 In vitro iohexol adsorption in cartridges with mesoporous styrene-divinylbenzene sorbent

Abstract Background and Aims Patients with pre-existing chronic kidney disease (CKD) present the highest risk of developing contrast-associated acute kidney injury (CA-AKI). Iodinated contrast agents such as iohexol (molecular weight 821 Da) don't bind to proteins and are easily removed by hemodialysis filters. However, the session time necessary to remove approximately 75% of the injected iohexol load is around six hours. Due to lack of evidence, current guidelines do not recommend to start hemodialysis in CKD patients in conservative management after the administration of iodinated contrast media to prevent or mitigate CA-AKI. Still, a strong rationale supports the removal of iodinated contrast media because of its nephrotoxicity. In this study, we aimed to investigate the capability of a mesoporous styrene-divinylbenzene sorbent to bind iohexol in vitro. Method We used 1,000 mL of saline solution spiked with 40 mL of iohexol 350 mg/mL in a closed-loop configuration. Iohexol concentration was 14 mg/mL. The amount of the iodinated radiocontrast was proportional to the amount used in complex percutaneous coronary interventions (worst-case scenario), around 200 mL, in a 70 kg person with an estimated blood volume of 5,000 mL. The solution circulated through a HA380 mini-module cartridge filled with 75g of mesoporous styrene-divinylbenzene sorbent beads at 250 ml/min. The experiment was carried out twice with the same setup. Samples were collected at eight-time points (0, 5, 10, 15, 20, 30, 40, and 60 minutes) from the reservoir to measure iohexol concentration. The analysis of the samples was carried out in duplicate. The removal ratio (RR) was calculated considering the initial concentration (C(0)) and the variation of the concentration during the experiment (C(t), where t is the time point), as follows: $RR( \% ) = \frac{{C( 0 ) - C( t )}}{{C( 0 )}}100$ Results In the first experiment, the removal ratios after 5, 30, and 60 minutes were 23.4%, 45.8%, and 52.9%, respectively on average. In the second experiment, the reduction ratios after 5, 30, and 60 minutes were 23.4%, 45.5%, and 53.1%, respectively on average. After 30 minutes, the adsorption curved plateaued, indicating cartridge saturation (Fig. 2). Conclusion This in vitro model demonstrated that HA380 sorbent cartridge was effective in removing iohexol. The use of hemoadsorption as a strategy to remove iodinated contrast media warrants further investigation because of its clinical potential to reduce the exposure to nephrotoxic contrast agents and CA-AKI.

Single-Center Retrospective Study on the Efficacy of Contrast-Enhanced Ultrasound for Detection of Endoleak After Endovascular Aortic Repair

Introduction: Surveillance for endoleak after endovascular aortic aneurysm repair with computed tomography angiography has the associated risks of radiation exposure and nephrotoxic contrast agents. The purpose of this study was to evaluate the performance of contrast-enhanced ultrasound in the detection of endoleak post–endovascular aortic aneurysm repair. Methods: A single-center retrospective cohort study was performed evaluating patients with abdominal aortic aneurysm treated with endovascular aortic aneurysm repair between October 29, 2017 and April 21, 2021 and follow-up imaging with both computed tomography angiography and contrast-enhanced ultrasound. The sample included 35 imaging combinations in 28 patients. Positive and negative results for detection of endoleak by contrast-enhanced ultrasound were tabulated as true positive, false positive, true negative, and false negative compared to computed tomography angiography and conventional angiography. Sensitivity, specificity, positive predictive value, and negative predictive value of contrast-enhanced ultrasound were calculated. Results: Out of 35 imaging combinations, endoleak was detected in 24 cases by computed tomography angiography and in 23 cases by contrast-enhanced ultrasound. Using computed tomography angiography as the reference standard, contrast-enhanced ultrasound yielded 96% sensitivity, 100% specificity, 100% positive predictive value, and 92% negative predictive value for endoleak detection. In the 23 cases of endoleak detection by both contrast-enhanced ultrasound and computed tomography angiography, contrast-enhanced ultrasound discerned the correct endoleak type in all 23 cases, while computed tomography angiography identified the correct endoleak type in 20 cases ( P = .2333). Discussion: Endoleak detection by contrast-enhanced ultrasound appears at least equivalent to computed tomography angiography. Some of the advantages of contrast-enhanced ultrasound in the surveillance of endoleak after endovascular aortic aneurysm repair include an avoidance of radiation, elimination of nephrotoxic contrast agents, reduction in costs, real-time imaging, discerning flow directionality, and visualizing endoleaks in regions previously embolized with coils/plugs/liquid embolic agents. Limitations include operator dependence and variables that obscure the visual field including obese body habitus. With these advantages and excellent comparison data, contrast-enhanced ultrasound should be considered as a first-line imaging modality for long-term surveillance of endoleaks after endovascular aortic aneurysm repair. Conclusion: Contrast-enhanced ultrasound is a safe and viable option for long-term surveillance post–endovascular aortic aneurysm repair.

The ARIA trial protocol: a randomised controlled trial to assess the clinical, technical, and cost-effectiveness of a cloud-based, ARtificially Intelligent image fusion system in comparison to standard treatment to guide endovascular Aortic aneurysm repair

BackgroundEndovascular repair of aortic aneurysmal disease is established due to perceived advantages in patient survival, reduced postoperative complications, and shorter hospital lengths of stay. High spatial and contrast resolution 3D CT angiography images are used to plan the procedures and inform device selection and manufacture, but in standard care, the surgery is performed using image-guidance from 2D X-ray fluoroscopy with injection of nephrotoxic contrast material to visualise the blood vessels. This study aims to assess the benefit to patients, practitioners, and the health service of a novel image fusion medical device (Cydar EV), which allows this high-resolution 3D information to be available to operators at the time of surgery.MethodsThe trial is a multi-centre, open label, two-armed randomised controlled clinical trial of 340 patient, randomised 1:1 to either standard treatment in endovascular aneurysm repair or treatment using Cydar EV, a CE-marked medical device comprising of cloud computing, augmented intelligence, and computer vision. The primary outcome is procedural time, with secondary outcomes of procedural efficiency, technical effectiveness, patient outcomes, and cost-effectiveness. Patients with a clinical diagnosis of AAA or TAAA suitable for endovascular repair and able to provide written informed consent will be invited to participate.DiscussionThis trial is the first randomised controlled trial evaluating advanced image fusion technology in endovascular aortic surgery and is well placed to evaluate the effect of this technology on patient outcomes and cost to the NHS.Trial registrationISRCTN13832085. Dec. 3, 2021

Coronary vasospasm testing: escape from the cath lab!

Coronary vasospasm stands as a widely acknowledged and frequent culprit behind chest pain, acute coronary syndrome, and sudden cardiac death, yet it remains a challenging diagnosis. Current guidelines recommend invasive coronary function testing to assess pathophysiology and mechanisms and to define treatment. In reality, this protocol is rarely applied, because it necessitates extended occupation of the cath lab, repetitive administration of nephrotoxic iodine contrast agents, the need for repeated testing on both coronary arteries leading to considerable radiation exposure, and significant direct expenses. The promising perspective for vasospasm testing is a noninvasive approach with advanced echocardiographic techniques, such as transthoracic Doppler echocardiography, with more sensitive indicators of ischemia. Hyperventilation and exercise tests are used for vasospasm directed testing, with assessment of the new parameters: coronary flow velocities and reserve, allowing to see deeper into macro and microvascular pathophysiology. Association between coronary flow, global longitudinal strain and microvascular dysfunction (MVD) and impaired values at hyperemia was previously demonstrated. Reduction in coronary flow velocity (CFV) despite heightened myocardial oxygen consumption and double product during hyperventilation are indicative of coronary vasospasm. Normal coronary angiography finding in patients with documented evidence of ischemia should initiate additional diagnostic testing in order to increase the yield of specific diagnosis in patients with suspected vasospasm, which could help to personalize treatment and prognosis. In order to achieve this, non-invasive provocative stress echocardiography tests should be included in the diagnostic workup. This approach, characterized by its simplicity, feasibility, safety, and efficacy, is currently undergoing extensive testing on a large scale.

Role of intravascular ultrasound and optical coherence tomography in intracoronary imaging for coronary artery disease: a systematic review.

Coronary angiography has long been the standard for coronary imaging, but it has limitations in assessing vessel wall anatomy and guiding percutaneous coronary intervention (PCI). Intracoronary imaging techniques like intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can overcome these limitations. IVUS uses ultrasound and OCT uses near-infrared light to visualize coronary pathology in unique ways due to differences in temporal and spatial resolution. These techniques have evolved to offer clinical utility in plaque characterization and vessel assessment during PCI. Meta-analyses and adjusted observational studies suggest that both IVUS and OCT-guided PCI correlate with reduced cardiovascular risks compared to angiographic guidance alone. While IVUS demonstrates consistent clinical outcome benefits, OCT evidence is less robust. IVUS has progressed from early motion detection to high-resolution systems, with smaller compatible catheters. OCT utilizes near infrared light to achieve unparalleled resolutions, but requires temporary blood clearance for optimal imaging. Enhanced visualization and guidance make IVUS and OCT well-suited for higher risk PCI in patients with diabetes and chronic kidney disease by allowing detailed visualization of complex lesions and ensuring optimal stent deployment and positioning in PCI for patients with type 2 diabetes and chronic kidney disease, improving outcomes. IVUS and recent advancements in zero- and low-contrast OCT techniques can reduce nephrotoxic contrast exposure, thus helping to minimize PCI complications in these high-risk patient groups. IVUS and OCT provide valuable insights into coronary pathophysiology and guide interventions precisely compared to angiography alone. Both have comparable clinical outcomes, emphasizing the need for tailored imaging choices based on clinical scenarios. Continued refinement and integration of intravascular imaging will likely play a pivotal role in optimizing coronary interventions and outcomes. This systematic review aims to delve into the nuances of IVUS and OCT, highlighting their strengths and limitations as PCI adjuncts.

Ultrasound Coded-Excitation Imaging for Endoleak Detection After Complex Endovascular Aortic Repair.

Several imaging modalities have been suggested for surveillance after fenestrated endovascular aortic repair in general and endoleak detection in specific. In the present project a coded excitation-based ultrasound (B-Flow) was investigated for endoleak detection after complex endovascular aortic repair. Patients post complex endovascular aortic repair (FEVAR or T/FEVAR) undergoing follow-up appointments including ultrasonography of the aorta at a vascular and endovascular surgery outpatient center were included in the study. B-Flow was compared with computed tomography angiography (CTA), Duplex ultrasound (DUS), and contrast-enhanced ultrasound (CEUS) regarding agreement and reliability for endoleak detection and characterization. In total, 47 follow-ups were included. They accumulated in a total of 149 imaging investigations. Endoleaks were discovered in 44.7% of B-Flow studies and a majority of these endoleaks were classified as type II. Agreement between B-Flow and other imaging modalities was good (>80.0%) in general. However, with B-Flow 6 and 2 endoleaks would have been missed compared with CEUS and CTA, respectively. Regarding endoleak classification, B-Flow had a strong agreement (94.5%) with CEUS in detected cases. Furthermore, in a limited subset analysis, imaging findings were externally validated using findings from angiography. Ultrasonography allows for endoleak detection and characterization without an invasive procedure or the use of potentially nephrotoxic contrast medium and can reduce radiation exposure. While CEUS mitigates issues of radiation and nephrotoxicity it still requires the intravenous application of contrast enhancers. Ultrasound coded-excitation imaging such as B-Flow could therefore further simplify endoleak surveillance after fenestrated endovascular aortic repair.

Ultrasound Surveillance is Feasible After Endovascular Aneurysm Repair

IntroductionSurveillance after endovascular aneurysm repair (EVAR) is traditionally done with computed tomography angiography (CTA) scans that exposes patient to radiation, nephrotoxic contrast media, and potentially increased risk for cancer. Ultrasound (US) is less labor intensive and expensive and might thus provide a good alternative for CTA surveillance. The aim of this study was to evaluate in real-life patient cohorts whether US is able to detect post-EVAR aneurysm-related complications similarly to CTA. MethodsThis retrospective study compared the outcome of consecutive patients who underwent EVAR for intact abdominal aortic aneurysm (AAA) and were surveilled solely by CTA (CTA-only cohort, n= 168) in 2000-2010 or by combined CTA and US (CTA/US cohort, n= 300) in 2011-2016, as a standard surveillance protocol in department of vascular surgery, Helsinki University Hospital. The CTA-only patients were imaged at 1, 3, and 12 months and annually thereafter. The CTA/US patients were imaged with CTA at 3 and 12 months, US at 6 months and annually thereafter. If there were suspicion of >5 mm aneurysm growth, CTA scan was performed. The patients were reviewed for imaging data, reinterventions, aneurysm ruptures, and death until December 2018. The two groups were compared for secondary rupture, aneurysm- and cancer-related death, reintervention related to AAA, and maximum aneurysm diameter increase >5 mm. The mean follow-up in the CTA-only cohort was 67 months and in CTA/US cohort 43 months. ResultsThe two cohorts were alike for basic characteristics and for the mean aneurysm diameter. The total number of CT scans for detecting aneurysm was 84.1/100 patient years in the CTA-only cohort compared to 74.5/100 patient years for US/CTA-cohort. 40 % of patients under combined CTA/US surveillance received one or more additional CTA scans. The two cohorts did not differ for 1-, 5- and 8-year freedom from aneurysm related death, secondary sac rupture, nor the incidence of rupture preventing interventions. ConclusionBased on the follow up data of this real-life cohort of 468 patients, combined surveillance with US and additional CTA either per protocol or due to suspicion of aneurysm-related complications had comparable outcome with sole CTA-surveillance. Thus, US can be considered a reasonable alternative for the CTA. However, our study showed also that the need of additional CTAs due to suspicion of endoleak or aneurysm non-related reasons is substantial.

Role of Contrast-Enhanced Ultrasound in Evaluation of Cystic Renal Mass.

Contrast-enhanced ultrasound (CEUS) allows excellent delineation of perfusion in septa and nodules without exposure to ionizing radiation or nephrotoxic contrast media. The aim of our study was to evaluate the role of CEUS for the assessment of cystic renal masses and compare its diagnostic performance with that of CECT. Exactly 40 patients diagnosed to have cystic renal masses on CECT scan were prospectively evaluated with CEUS and were assigned a Bosniak class. Based on results of final histopathology and clinical follow-up, internal validity of both CEUS and CECT was evaluated, including agreement between these two modalities. Out of the 40 patients (mean size 3.1 ± 2.5 cm), 23 patients had benign lesions and 17 patients had malignant lesions. For CEUS, the sensitivity and negative predictive value was 100%, the specificity and positive predictive value was 73.9%. For CECT, the sensitivity and negative predictive value were 88.2 and 83.3%, respectively, whereas the specificity and positive predictive value was 87 and 90.9%, respectively. Both imaging modalities had similar accuracy with fair to good agreement with the final diagnosis (Κ = 0.71 and 0.75 for CEUS and CECT, respectively). Concordance between CEUS and CECT was seen in 29 patients (72.5%) with fair agreement between the two modalities (K = 0.66). CEUS has comparable accuracy with CECT and could be used as screening modality to rule out the presence of complex cystic renal masses without exposure of nephrotoxic contrast media and ionizing radiation.

Peripheral Arterial Disease: A Narrative Review.

Peripheral arterial disease (PAD) describes the partial or complete occlusion of blood flow in the distal arteries of the body. A decreased arterial patency may occur due to a reduction in the elasticity or diameter of the vessel. The goal of interventions is to decrease incidence and reduce complications by identifying and minimizing the primary causes. This paper discusses PAD affecting the aortoiliac, common femoral, and femoropopliteal arteries. In a significant portion of the population, PAD may lack usual symptoms such as limb pain, claudication, and diminished pulses. Imaging techniques become crucial to ensuring timely diagnosis, monitoring treatment effectiveness, and preventing recurrence. Duplex ultrasound (DUS) is a cheap and non-invasive preliminary technique to detect atherosclerotic plaques and grade arterial stenosis. Magnetic resonance angiography (MRA) provides the added advantage of minimizing artifacts. Digital subtraction angiography (DSA) remains the gold standard for grading the degree of stenosis but is only employed second-line to DUS or MRA due to the high dose of nephrotoxic contrast. Computed tomography angiography (CTA) is able to overcome the anatomical limitations of DUS and MRA and proves to be a suitable alternative to DSA in patients with renal disease. Preventative measures involve monitoring blood pressure, cholesterol levels, and tobacco usage. First-line treatment options include endovascular procedures as well as surgical interventions in cases of significant arterial involvement. Endovascular treatments involve the use of balloon angioplasty, drug-coated balloons, and drug-coated stents, to name a few, that serve as minimally invasive techniques to manage PAD. Surgical procedures, although more complex, are considered gold-standard treatment options for long and intricate lesions. Endovascular methods are generally preferred over surgical options as the complication risk is severely reduced and the rates of reintervention are comparable to surgical options.

Incidental Findings in Pediatric Patients: How to Manage Liver Incidentaloma in Pediatric Patients

The World Federation for Ultrasound in Medicine and Biology (WFUMB) is addressing the issue of incidental findings (IFs) with a series of publications entitled "Incidental imaging findings-the role of ultrasound". IFs in the liver of newborns and children are rare and much less commonly encountered than in adults; as a result, they are relatively much more frequently malignant and life-threatening, even when they are of benign histology. Conventional B-mode ultrasound is the well-established first line imaging modality for the assessment of liver pathology in pediatric patients. US technological advances, resulting in image quality improvement, contrast-enhanced ultrasound (CEUS), liver elastography and quantification tools for steatosis have expanded the use of ultrasound technology in daily practice. The following overview is intended to illustrate incidentally detected liver pathology covering all pediatric ages. It aims to aid the examiner in establishing the final diagnosis. Management of incidentally detected focal liver lesions (FLL) needs to take into account the diagnostic accuracy of each imaging modality, the patient's safety issues (including ionizing radiation and nephrotoxic contrast agents), the delay in diagnosis, the psychological burden on the patient and the cost for the healthcare system. Moreover, this paper should help the pediatric clinician and ultrasound practitioner to decide which pathologies need no further investigation, which ones require interval imaging and which cases require further and immediate diagnostic procedures.

Global Perspectives in Acute Kidney Injury: Spain.

Global Perspectives in Acute Kidney Injury: Spain.

Aneurysm Geometry Analyzed by the Novel Three-Dimensional Tomographic Ultrasound Relates to Abdominal Aortic Aneurysm Growth

Abdominal aortic aneurysms (AAAs) are increasingly screen-detected and many small aneurysms enter surveillance. Computed tomography identifies characteristics that can predict subsequent AAA growth but ionizing radiation and nephrotoxic contrast disadvantage its use in surveillance. We investigated whether duplex and 3-dimensional tomographic ultrasound identified features associated with AAA growth in patients on AAA surveillance. Duplex and three-dimensional tomographic ultrasound imaging was performed independently by 2 vascular scientists in 128 AAA surveillance patients who all had AAA growth measured over at least 2 years. Diameter, cross-sectional area, length, volume, wall thickness/volume, and intraluminal thrombus were measured. Pulsatility using maximum systolic and minimum diastolic diameters corrected for diameter and distensibility (consisting of strain and stiffness) were also calculated. AAA growth rate correlated with AAA diameter (r 0.43), volume (r 0.46), and cross-sectional area (r 0.42) (P < 0.01). Measuring wall thickness was inaccurate, but wall volume (corrected for AAA volume) inversely related to growth rate (r -0.43, P < 0.01). On a multivariate analysis, diameter and wall volume (r2adjusted 0.22, P < 0.01) improved prediction of growth rate compared with diameter alone (r2adjusted 0.18, P<0.01). Intraluminal thrombus volume, strain distensibility, and elastic distensibility were not significantly associated with AAA growth. AAA growth most strongly related to AAA volume and inversely to wall volume. AAA volume and wall volume may prove useful in the prediction of AAA growth rates.

Abstract No. 370 Single center retrospective study on the efficacy of contrast enhanced ultrasound for detection of endoleak after endovascular aortic repair

Surveillance for endoleak after endovascular aortic aneurysm repair (EVAR) with CT angiography (CTA) commits patients to lifelong radiation exposure and nephrotoxic contrast agents. The purpose of this study was to evaluate the performance of contrast-enhanced ultrasound (CEUS) in the detection of endoleak post-EVAR.

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

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. 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. 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). 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.

Subclavian Artery Calcification: A Narrative Review.

Subclavian artery calcification (SAC) affects 2% of the population and presents a serious risk of developing into subclavian steal syndrome (SSS). Risk factors for plaque formation of the subclavian artery include diabetes, hypertension, and smoking. While SAC generally presents as asymptomatic, symptoms in severe cases may include numbness, pain at rest, and ischemic gangrene. Patients with severe SSS are at high risk of developing neurological symptoms as a result of vertebrobasilar insufficiency affecting posterior cerebral perfusion. On physical examination, SSS is preliminarily diagnosed from bilateral inter-arm systolic blood pressure discrepancy (>10 mmHg), which can be further confirmed with vascular imaging. Duplex ultrasound (DUS) is a cost-effective and non-invasive baseline technique for visualizing luminal stenosis and quantifying peak systolic velocity (PSV). Computed tomography angiography (CTA) provides high-quality, fast, three-dimensional (3D) imaging at the cost of introducing nephrotoxic contrast agents. Magnetic resonance angiography (MRA) is the safest 3D imaging modality, without the use of X-rays and contrast agents, that is useful in assessing plaque characteristics and degree of stenosis. DUS-assisted digital subtraction angiography (DSA) remains the gold standard for grading the degree of stenosis in the subclavian artery and determining the distance between the puncture site and lesion, which can be carried out in a combined procedure with endovascular management strategies. The fundamental treatment options are surgical and endovascular intervention. Endovascular treatment options include percutaneous transluminal angiography (PTA) for recanalization of the stenosed vessel and permanent balloon stenting to prevent collapse after PTA. Overall, the benefits of endovascular management encompass faster recovery, lower stenosis recurrence rate, and lower incidence of complications, making it the treatment of choice in low-risk patients. Surgical interventions, although more complex, are considered gold-standard treatment options.

Abstract 135: A case of acquired Gitelman syndrome presenting as hypokalemic paralysis and AKI

Introduction: Gitelman syndrome is usually an inherited disorder, it is induced by defect in the thiazide sensitive Na –Cl co-transporter in distal tubules. Case reports on hypokalemia, AKI secondary to GS has been discussed in present case report.Clinical Case: A 18 year old female referred from department of General Medicine as a case of AKI having recurrent hypokalemia. She gave history of hypokalemic paralysis. There was no potential cause of dehydration such as diarrhoea, vomiting, nephrotoxic agent intake or contrast exposure. Family history was negative. During current hospitalization, she was normotensive with normal renal function test. Other electrolyte levels including calcium and routine laboratory parameters were determined to be normal. Kidney dimensions and echogenicity were determined to be normal without hydronephrosis in the urinary system as oer USG finding. Further workup for hypokalemia revealed urine potassium creatinine ratio (17 mmol/g), ABG (pH 7.44, bicarbonate 26.5 mmol/l), urine chloride (111.3 mmol/l) and urine calcium creatinine ratio (0.05 mmol/mmol) respectively with serum Mg (1.7 mg/dl) on lower range. Based on above findings, a diagnosis of Gitelman syndrome has been made. Autoimmune etiology were ruled out. These finding suggested that patient had AKI secondary to hypokalemia. She was started on oral potassium supplementation and magnesium supplementation.Conclusion: GS is a rare tubulopathy transmitted as an autosomal recessive trait. It is caused by mutation in thiazide sensitive Na Cl co-transporter coding gene, SLC12A3. Patients may be referred with hypokalemia, hypomagnesemia and metabolic alkalosis associated muscular weakness and cramping. By contrast, worsening hypokalemia and profound volume depletion as the predisposing factors for ischemic AKI appears to coexist.

Use of Duplex Ultrasound Imaging Post-Endovascular Aneurysm Repair (EVAR)

Individuals who undergo endovascular aneurysm repair (EVAR) require annual surveillance to detect endoleaks and guide surgical management. Endoleaks are classified into five categories based on the direction of blood flow in the aneurysmal sac outside the graft, determining prognosis and management. Currently, evaluation with computed tomography angiography (CTA) is favored as the gold standard for evaluation of endoleak. However, there is associated patient exposure to nephrotoxic intravenous contrast as well as radiation. Each of the five subtypes of endoleak can be characterized and subsequently followed on ultrasound. This practice offers a safe and cost-effective alternative to CTA.

Mon faux-ami l'angiographie coronaire

Coronary angiography has been a long-standing friend since the first selective injection by Sones in 1958. More than 400,000 coronary angiographies are performed each year in France for the diagnosis and treatment of ischemic heart disease. In just over 60 years, examinations have become simpler, with imaging that has considerably progressed. Nevertheless, it remains an invasive and radiating examination and requires an injection of a potentially nephrotoxic contrast medium. It is a two-dimensional projection of a luminogram of small arteries, in perpetual movement. The technical realization must be perfect, the analysis of the images must be careful. It is important to be aware of the pitfalls and limitations of the examination, and to rely on complementary techniques to resolve ambiguities, whether functional (FFR, IMR) or morphological (IVUS, OCT). Although non-invasive explorations, such as coroscanner, are in full development, these alternative methods have other limitations (lack of resolution, artifacts related to calcifications) which mean that angiography often remains essential for the diagnosis of coronary artery disease, indispensable for deciding on treatment and guiding revascularization. All of these elements make coronary angiography the definition of a friend: someone you know well... but you love anyway.

Detecting Aortic Valve Anomaly From Induced Murmurs: Insights From Computational Hemodynamic Models.

Patients who receive transcatheter aortic valve replacement are at risk for leaflet thrombosis-related complications, and can benefit from continuous, longitudinal monitoring of the prosthesis. Conventional angiography modalities are expensive, hospital-centric and either invasive or employ potentially nephrotoxic contrast agents, which preclude their routine use. Heart sounds have been long recognized to contain valuable information about individual valve function, but the skill of auscultation is in decline due to its heavy reliance on the physician’s proficiency leading to poor diagnostic repeatability. This subjectivity in diagnosis can be alleviated using machine learning techniques for anomaly detection. We present a computational and data-driven proof-of-concept analysis of a novel, auscultation-based technique for monitoring aortic valve, which is practical, non-invasive, and non-toxic. However, the underlying mechanisms leading to physiological and pathological heart sounds are not well-understood, which hinders development of such a technique. We first address this by performing direct numerical simulations of the complex interactions between turbulent blood flow in a canonical ascending aorta model and dynamic valve motion in 29 cases with healthy and stenotic valves. Using the turbulent pressure fluctuations on the aorta lumen boundary, we model the propagation of heart sounds, as elastic waves, through the patient’s thorax. The heart sound may be recorded on the epidermal surface using a stethoscope/phonocardiograph. This approach allows us to correlate instantaneous hemodynamic phenomena and valve motion with the acoustic response. From this dataset we extract “acoustic signatures” of healthy and stenotic valves based on principal components of the recorded sound. These signatures are used to train a linear discriminant classifier by maximizing correlation between recorded heart sounds and valve status. We demonstrate that this classifier is capable of accurate prospective detection of anomalous valve function and that the principal component-based signatures capture prominent audible features of heart sounds, which have been historically used by physicians for diagnosis. Further development of such technology can enable inexpensive, safe and patient-centric at-home monitoring, and can extend beyond transcatheter valves to surgical as well as native valves.