Parameter estimation to study the immediate impact of aortic cross-clamping using reduced order models

Aortic cross-clamping is a common strategy during vascular surgery, however, its instantaneous impact on hemodynamics is unknown. We, therefore, developed two numerical models to estimate the immediate impact of aortic clamping on the vascular properties. To assess the validity of the models, we recorded continuous invasive pressure signals during abdominal aneurysm repair surgery, immediately before and after clamping. The first model is a zero-dimensional (0D) three-element Windkessel model, which we coupled to a gradient-based parameter estimation algorithm to identify patient-specific parameters such as vascular resistance and compliance. We found a 10% increase in the total resistance and a 20% decrease in the total compliance after clamping. The second model is a nine-artery network corresponding to an average human body in which we solved the one-dimensional (1D) blood flow equations. With a similar parameter estimation method and using the results from the 0D model, we identified the resistance boundary conditions of the 1D network. Determining the patient-specific total resistance and the distribution of peripheral resistances through the parameter estimation process was sufficient for the 1D model to accurately reproduce the impact of clamping on the pressure waveform. Both models gave an accurate description of the pressure wave and had a high correlation (R2 >.95) with experimental blood pressure data.Fil: Ventre, Jeanne. Centre National de la Recherche Scientifique; FranciaFil: Politi, Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Fernández, Juan M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Ghigo, Arthur R.. Université de Toulouse; FranciaFil: Gaudric, Julien. Centre National de la Recherche Scientifique; Francia. Université de Toulouse; FranciaFil: Wray, Sandra. Universidad Favaloro; ArgentinaFil: Lagaert, Jean Baptiste. Université Paris Sud; FranciaFil: Armentano, Ricardo Luis. Universidad de la República; UruguayFil: Capurro, Claudia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Fullana, José Maria. Centre National de la Recherche Scientifique; FranciaFil: Lagrée, Pierre Yves. Centre National de la Recherche Scientifique; Franci

Morphometry of thoracic aortic aneurysms : from CT scan anatomy to numerical model

Rationnel : L’étude de l’anatomie de la crosse aortique a évolué pour optimiser le traitement des anévrismes par endoprothèse.Objectifs : I : caractériser les modifications morphométriques de la crosse induites par un anévrisme. II : évaluer la faisabilité des dispositifs endovasculaires actuels pour traiter les anévrismes de la crosse. III : créer un outil automatisé de mesure pour évaluer les angulations induites par ces déformations. IV : valider un modèle numérique de simulation 0D de la mécanique vasculaire en le confrontant à des données in vivo.Résultats : I : nous avons montré sur une étude scannographique que les anévrismes thoraciques s’accompagnaient d’un étirement bi directionnel de la paroi et d’une rotation de la crosse antérieure ou postérieure selon la localisation de l’anévrisme. II : parmi 56 malades opérés chirurgicalement d’anévrismes de la crosse, l’étude rétrospective de leur scanner montrait qu’aucun n’avait les critères anatomiques pour permettre une endoprothèse branchée. III : nous avons créé un logiciel de calcul automatisé des points de courbure maximale de l’aorte à partir d’une analyse continue du rayon de courbure de la ligne centrale. Sa pertinence a été validée par sa concordance avec la détermination visuelle des points. IV : nous avons confronté la déformation de l’onde de pression artérielle après clampage et déclampage de l’aorte chez 11 patients avec une bonne corrélation et accord entre un modèle numérique et des enregistrements continus intravasculaires. Conclusion : Les progrès dans l’analyse de la conformation de l’aorte et de la mécanique vasculaire sont nécessaires à l’adaptation de nouveaux substituts endovasculaires.Rational: Research on the anatomy of the aortic arch has been fueled by the need of a comprehensive analysis of this structure in the setting of endovascular repair. Aneurysmal disease causes distortions in areas where the implantation of stent grafts undergo major stress. Objectives: I: To characterize the morphometric modifications of the aortic arch induced by a thoracic aneurysm. II: To evaluate the feasibility of current endovascular devices in treating aortic arch aneurysms. III: To create an automated measurement tool for assessing the angulations induced by these deformations. IV: To validate a 0D numerical simulation model of vascular mechanics by comparing its predictions with in vivo data.Results: I: In a study of 78 CT scan, thoracic aneurysms were associated with bi-directional wall stretching and anterior or posterior rotation according to the aneurysm’s location. II: A retrospective study of the CT scans of 56 patients who underwent aortic arch aneurysm surgical repair showed that none of these patients had the anatomical criteria for a stent graft implantation. III: An automated software for calculating the aortic angulations from a continuous analysis of the curvature radius of the central line was developed and validated against the visual assessment of points. IV: Changes in the morphology of blood pressure waves after aortic clamping and unclamping were studied in 11 patients with a good correlation and agreement between the numerical model and continuous intravascular measurements. Conclusion: Advances in the analysis of aortic geometry and the simulation of vascular mechanics are necessary for the adaptation of new endovascular devices

Etude de la migration proximale des endoprothèses aortiques après exclusion endovasculaire des anévrismes de l'aorte abdominale

LILLE2-BU Santé-Recherche (593502101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Correlation between Ultra-Wide-Field Retinal Imaging Findings and Vascular Supra-Aortic Changes in Takayasu Arteritis

International audience(1) Background: Takayasu arteritis (TA) is a chronic inflammatory large-vessel vasculitis. Ultra-wide-field imaging allows describing the retinal lesions in these patients and correlating them with vascular supra-aortic stenosis. (2) Methods: In total, 54 eyes of 27 patients diagnosed with TA were included, and a complete ophthalmological examination was performed, including UWF color fundus photography (UWF-CFP), fluorescein angiography (UWF-FA), and computed tomography angiography measuring supra-aortic stenosis. Eleven patients underwent Doppler ultrasound imaging assessing the blood flow velocity (BFV) in the central retinal artery (CRA). (3) Results: Microaneurysms were detected in 18.5% of eyes on fundus examination, in 24.4% of eyes on UWF-CFP, and in 94.4% of eyes on UWF-FA. The number of microaneurysms significantly correlated with the presence of an ipsilateral supra-aortic stenosis (p = 0.026), the presence of hypertension (p = 0.0011), and the duration of the disease (p = 0.007). The number of microaneurysms per eye negatively correlated with the BFV in the CRA (r = −0.61; p = 0.003). (4) Conclusions: UWF-FA improved the assessment of TA-associated retinal findings. The significant correlation between the number of microaneurysms and the BFV in the CRA gives new insight to our understanding of Takayasu retinopathy. The total number of microaneurysms could be used as an interesting prognostic factor for TA

Importance of Early Diagnosis and Care in Knee Dislocations Associated with Vascular Injuries

International audienceBackground: Arterial injury secondary to acute knee dislocation (KD) is a rare but devastative complication. The aim of this study is to evaluate functional sequelae and factors of poor prognosis.Methods: A retrospective monocentric series of consecutive KD with acute ischemia by popliteal artery injury was analyzed between 2005 and 2017. The main outcome was the amputation rate.Results: Sixteen dislocations were included. Nine (56%) were due to public road accidents, 5 (31%) were due to falls from height, and 2 (13%) were due to sports injuries. Dislocation had occurred in the posterior location in 8 (50%) cases. Regarding arterial injury, there were 7 (44%) ruptures, 7 (44%) dissections, and 2 (13%) isolated thromboses. Eleven (69%) KDs with vascular trauma were associated with signs of acute ischemia. Revascularization was achieved by anatomical venous bypass in 14 (88%), resection and direct anastomosis in one (6%), and isolated thrombectomy in one (6%). Median time to surgery (time between trauma and vascular repair) was 7 hours (3.25-60.92 hours). Primary revascularization was performed in 12 (75%) cases. In three cases (19%), orthopedic reduction and stabilization were performed first. In one case, (6%) three-step management with vascular shunt at first, then with knee stabilization, and finally vascular bypass was carried out. Stabilization was achieved by using an external fixator in 13 (82%) cases, by open reduction and internal fixation in one case (6%), by ligamentoplasty in one (6%), and by using a long leg cast in one (6%). Fasciotomy was required in 12 (75%) cases. Two patients had early vascular complications, and 2 had early systemic complications. Three secondary transfemoral amputations were performed. Median follow-up duration was 23 months. No secondary amputation was recorded. At the end of follow-up, functional outcomes were evaluated using the Oxford Knee Score (OKS). The median OKS was 30 versus the pretrauma median OKS of 47 (P < 0.00028). No risk factor associated with limb amputation has been highlighted.Conclusions: Analysis of these results provided indications for therapeutic management of this condition. This study shows poor functional outcomes because of severity of vascular lesion in patients with orthopedic trauma but with healthy arteries

Calculation of the aortic arch angles from three-dimensional reconstructions of computed tomography scans: Comparison between an automated program and visual assessment

Background: The curvature of the aortic arch is associated with the risk of endoleak formation after thoracic endovascular aortic repair (TEVAR). However, the adequate assessment of the angles of the aorta continues to represent a major difficulty. We developed a new program based on three-dimensional (3D) reconstructions of computed tomography (CT) scans to objectively identify the location of the aortic points of maximum curvature, and to automatically calculate the main aortic arch angles, comparing final values with visual assessment methods. Methods: This is a cross-sectional validation study of a convenience sample of subjects with multislice CT angiography scans of the thoracic aorta from an institutional imaging database. The center lumen line (CLL) of the aorta was determined semi-automatically using Endosize software. The points of maximum curvature on the CLL were determined by two methods: visually by two physicians and through a custom program. Results: The study enrolled 9 subjects: 4 with thoracic aneurysms and 5 with normal aortas. The inter-observer and inter-method correlation, agreement and reliability for each of the 3D spatial coordinates of the points of maximum curvature were appropriate. However, the aortic angles determined by visual assessment showed a very low to moderate correlation and reliability with those determined by our custom program. Conclusion: An automated custom program can reflect clinician's intuitive assessment of the location of points of maximum curvature and translate it into aortic angles with an apparently higher precision, reducing potential error and user time.Fil: Gaudric, Julien. Université Pierre et Marie Curie; Francia. Hôpitaux Universitaires La Pitié-Salpêtrière; Francia. Sorbonne University; FranciaFil: Politi, María Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Fernández, Juan Manuel Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Carre, Emmanuelle. Sorbonne University; FranciaFil: Capurro, Claudia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Fullana, Jose Maria. Sorbonne University; Franci