A 74-year-old woman with dyspnoea and a mass in the right atrium

A 74-year-old woman was admitted with pericardial effusion causing haemodynamic instability. On echographic and radiological examination, a mass was identified in the right atrium, extending into the epicardial layer. In the differential diagnosis of a cardiac mass, benign primary lesions like a myxoma must be distinguished from rare primary cardiac malignancies like sarcomas or more frequent secondary tumours. These include localisations of lymphomyeloproliferative disease and metastases of a melanoma or various subtypes of carcinoma. In this case, histopathological examination of a surgical biopsy showed findings consistent with a high-grade angiosarcoma. Because of the size and localisation, as well as the presence of a possible metastasis in the rib, surgical treatment was not possible. After diagnosis, the patient developed multiple additional metastasis. She received palliative radiotherapy to control the pain and died 10 months after the initial diagnosis was made. Median reported survival is 6 months

Numerical evaluation and experimental validation of pressure drops across a patient-specific model of vascular access for hemodialysis

In this work we investigated the possibility to predict the pressure drops across a patient-specific arteriovenous fistula (AVF) by means of an open-source hemodynamics solver aimed at convection-dominated incompressible flows. To account for the very high flow rates that develop in AVFs we considered a wide range of steady input flow conditions (corresponding to Reynolds numbers 100, 200, 550, 1000, 1500, and 2000), and compared with experiments for over 200 flow rates, up to Reynolds 2000. Three meshes for the numerical model, based on a micro-CT acquisition of the in vitro silicon model, were generated, in order to perform a h-refinement study and assess the mesh density allowing to correctly estimate the losses across the anastomosis. For the sake of validation, in addition to pressure assessment, the velocity solutions for Re 550 and 1000 were compared with particle image velocimetry (PIV) acquisitions. Once the solver was validated we also simulated pulsatile input flow conditions to investigate the role of pulsatility in predicting pressure drops. When the finer grid is considered almost all the experimental values for the pressure drop vs. flow measurements are within the standard deviation range of the numerical pressure drops. For the PIV validation, a good agreement is observed between in vitro data and numerical results. The ability to simulate unstable convection-dominated flows in complex 3D geometries is demonstrated and more insight is obtained about the non-common physiological flow conditions induced by fistula creation

Validation of a patient-specific hemodynamic computational model for surgical planning of vascular access in hemodialysis patients

Vascular access dysfunction is one of the main causes of morbidity and hospitalization in hemodialysis patients. This major clinical problem points out the need for prediction of hemodynamic changes induced by vascular access surgery. Here we reviewed the potential of a patient-specific computational vascular network model that includes vessel wall remodeling to predict blood flow change within 6 weeks after surgery for different arteriovenous fistula configurations. For model validation, we performed a multicenter, prospective clinical study to collect longitudinal data on arm vasculature before and after surgery. Sixty-three patients with newly created arteriovenous fistula were included in the validation data set and divided into four groups based on fistula configuration. Predicted brachial artery blood flow volumes 40 days after surgery had a significantly high correlation with measured values. Deviation of predicted from measured brachial artery blood flow averaged 3% with a root mean squared error of 19.5%, showing that the computational tool reliably predicted patient-specific blood flow increase resulting from vascular access surgery and subsequent vascular adaptation. This innovative approach may help the surgeon to plan the most appropriate fistula configuration to optimize access blood flow for hemodialysis, potentially reducing the incidence of vascular access dysfunctions and the need of patient hospitalization