Maurizio Domanin

Blood Flow Velocity Field Estimation Via Spatial Regression With PDE Penalization

We propose an innovative method for the accurate estimation of surfaces and spatial fields when prior knowledge of the phenomenon under study is available. The prior knowledge included in the model derives from physics, physiology, or mechanics of the problem at hand, and is formalized in terms of a partial differential equation governing the phenomenon behavior, as well as conditions that the phenomenon has to satisfy at the boundary of the problem domain. The proposed models exploit advanced scientific computing techniques and specifically make use of the finite element method. The estimators have a penalized regression form and the usual inferential tools are derived. Both the pointwise and the areal data frameworks are considered. The driving application concerns the estimation of the blood flow velocity field in a section of a carotid artery, using data provided by echo-color Doppler. This applied problem arises within a research project that aims at studying atherosclerosis pathogenesis. Supplementary materials for this article are available online.

Role of bypass, endarterectomy, extra-anatomic bypass and endovascular surgery in unilateral iliac occlusive disease: a review of 1257 cases.

Some 1257 patients who had undergone revascularization procedures for unilateral iliac occlusions were reviewed retrospectively. A total of 824 patients were operated upon using conventional operations, 165 patients had femorofemoral bypass and 268 were treated using endovascular surgery techniques. Revascularization was performed through an extraperitoneal approach by means of iliac thromboendarterectomy (560) or iliac femoral bypass (264) if there was a total occlusion of either the common or external iliac artery (group 1). A femorofemoral crossover bypass was inserted when the operative risk was considered to be high (group 2). Endovascular procedures (percutaneous transluminal angioplasty 234, laser percutaneous transluminal angioplasty 11, stenting 22, atherectomy one) were used in recent years to treat stenoses or occlusions of 3 cm or less (group 3). The indications for operation were severe claudication in 79.7% in group 1 and 92.6% in group 3, whereas in group 2 66.7% of patients presented with symptoms of more advanced ischaemia. The immediate patency rate was 97.0% after extraperitoneal reconstructive surgery. 96.9% in the femorofemoral group and 92.1% in patients having an endovascular procedure. The operative mortality rate was 0.7, 4.2 and 0.3% for groups 1–3. respectively. The 5-year patency rate, analysed by the life-table method, was 77.9% in group 1, 75.3% in group 2 and 73.7% in group 3 (P= n.s., log rank test) The different revascularization techniques were chosen on the basis of the type of disease present and the patients general condition. All procedures appeared to be effective when correctly selected.

Impact of hemodynamics on lumen boundary displacements in abdominal aortic aneurysms by means of dynamic computed tomography and computational fluid dynamics

The aim of the present work is to quantitatively assess the three-dimensional distributions of the displacements experienced during the cardiac cycle by the luminal boundary of abdominal aortic aneurysm (AAA) and to correlate them with the local bulk hemodynamics. Ten patients were acquired by means of time resolved computed tomography, and each patient-specific vascular morphology was reconstructed for all available time frames. The AAA lumen boundary motion was tracked, and the lumen boundary displacements (LBD) computed for each time frame. The intra-aneurysm hemodynamic quantities, specifically wall shear stress (WSS), were evaluated with computational fluid dynamics simulations. Co-localization of LBD and WSS distributions was evaluated by means of Pearson correlation coefficient. A clear anisotropic distribution of LBD was evidenced in both space and time; a combination of AAA lumen boundary inward- and outward-directed motions was assessed. A co-localization between largest outward LBD and high WSS was demonstrated supporting the hypothesis of a mechanistic relationship between anisotropic displacement and hemodynamic forces related to the impingement of the blood on the lumen boundary. The presence of anisotropic displacement of the AAA lumen boundary and their link to hemodynamic forces have been assessed, highlighting a new possible role for hemodynamics in the study of AAA progression.

Guidelines for Venous Thromboembolism and Clinical Practice in Italy: A Nationwide Survey

Venous thromboembolism (VTE) is a common health problem for todays society, and considering the role that it plays in surgical patients (general surgery, gynecology, and orthopedics), new advances in our understanding of the procedures and trauma characteristics are relevant and necessary. The most important and recently published guidelines concerning this problem have been taken into consideration, leading to articulate investigations and data evaluation. This project has proposed a data-survey framework available as a questionnaire in order to investigate application of the guidelines for VTE throughout the national territory. Of the total 714 Italian centers, a random sample of 214 were contacted and asked to take part in this study; of these, 146 replied (20.4% of total and 68.2% of the sample): 48 departments of general surgery, 46 departments of gynecology, and 52 departments of orthopedics. About 70% of the centers has appropriate information about surgery as a risk factor for VTE. The answers have provided evidence of an adequate knowledge of the instrumental and laboratory diagnostic pathways, useful to confirm the diagnosis of TE (80%). Data waiting compared with morbidity and mortality rates related to deep vein thrombosis and pulmonary embolism showed an increase of mortality associated with the diagnostic data timing of supply, with an exponential trend linked to the data acquisition delay. Both risk stratification and adequate application of prophylaxis together with treatment devices represent a real tool to control morbidity and mortality for VTE. Moreover, diagnostic data waiting significantly influences adequate prophylaxis. In Italy, only 40% of the centers are ready to provide diagnostic data within 12 hr.

Pharmacokinetics of enteric‐coated aspirin and inhibition of platelet thromboxane A2 and vascular prostacyclin generation in humans

We evaluated whether an enteric‐coated aspirin formulation showed a “presystemic” component in its antiplatelet effect and if so would spare vascular cyclooxygenase. In six healthy volunteers, 30 to 45 minutes after ingestion of 325 mg enteric‐coated aspirin, platelet thromboxane A2 generation was inhibited by about 20% before any drug could be detected in the peripheral venous blood. A further decline in thromboxane A2 generation occurred with appearance of aspirin in blood between 60 and 240 minutes. No presystemic component could be detected after 325 mg aspirin tablets. Ten patients undergoing saphenectomy received 325 mg of either aspirin tablet or enteric‐coated aspirin; 12 hours later platelet thromboxane A2 and peripheral vascular prostacyclin generation were significantly reduced by 98% and 58%, respectively. The effects of the two aspirin formulations were not different. Aspirin formulations with “presystemic” component in their antiplatelet effect may not necessarily result in sparing of peripheral vascular cyclooxygenase.

Large eddy simulations of blood dynamics in abdominal aortic aneurysms

We study the effects of transition to turbulence in abdominal aortic aneurysms (AAA). The presence of transitional effects in such districts is related to the heart pulsatility and the sudden change of diameter of the vessels, and has been recorded by means of clinical measures as well as of computational studies. Here we propose, for the first time, the use of a large eddy simulation (LES) model to accurately describe transition to turbulence in realistic scenarios of AAA obtained from radiological images. To this aim, we post-process the obtained numerical solutions to assess significant quantities, such as the ensemble-averaged velocity and wall shear stress, the standard deviation of the fluctuating velocity field, and vortical structures educed via the so-called Q-criterion. The results demonstrate the suitability of the considered LES model and show the presence of significant transitional effects around the impingement region during the mid-deceleration phase.

Spontaneous Rupture of Multiple Occipital Artery Aneurysms in a Patient With Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF-1) is an autosomal dominant genetic disorder, mainly characterized by skin and peripheral nervous system abnormalities. Uncommonly, NF-1 may be associated with peripheral or supra-aortic trunks artery aneurysms. We report a case of symptomatic multiple occipital artery aneurysms detected in a 53-year-old woman affected by sporadic NF-1. An endovascular approach was performed to exclude aneurysms and to stop laterocervical spontaneous hematoma.

Acute hemifacial ischemia as a late complication of carotid stenting

Concerns about carotid artery stenting (CAS) center primarily on procedural complications like acute occlusion, stroke, and long-term intrastent restenosis. External carotid artery (ECA) thrombosis is observed during CAS follow-up, but it often remains asymptomatic or, at worst, results in jaw claudication. We report here a case of late occlusion of the ECA after CAS with symptoms of acute homolateral facial ischemia as well as pain, cyanosis, tongue numbness, and skin coldness. The patient was submitted to local thrombolysis and balloon angioplasty with regression of symptoms after recanalization. With this report, we add a caveat about blockage of the ECA ostium during CAS.

Emergency Hybrid Approach to Ruptured Femoral Pseudoaneurysm in HIV-positive Intravenous Drug Abusers

BACKGROUND Chronic traumatism of the common femoral artery due to intravenous injection in drug abusers, in association with local infections and arterial wall weakening caused by human immunodeficiency virus (HIV), can lead to the development of pseudoaneurysms (PSAs). Rupture of PSA is a dramatic event in such patients, and its correction is difficult and controversial. Most of the cases reported describe open surgical elective options, which consist in ligation, repair, or substitution of the damaged arterial segment, using when possible biological grafts. In literature, few cases describe an endovascular repair with covered stent deployment. METHODS We present 2 cases of HIV-positive intravenous injection in drug abusers who needed emergency treatment for active bleeding in ruptured PSA of the right common femoral artery. In both cases, under general anesthesia needed for lack of patients compliance and unstable hemodynamics, a short dissection to the distal superficial femoral artery was required. RESULTS Then, maintaining a manual compression on the bleeding site to stop hemorrhage, we deployed a covered stent graft in the site of the arterial breakdown through a retrograde approach. CONCLUSIONS The favorable results and progressive healing of wound and local infections persuaded us not to perform any further surgical correction. The absence of recurrences and late complications, after 3 years in the first case and 1 year in the second one, lead us to consider this hybrid endovascular approach as a valuable alternative to open surgery in HIV intravenous injection in drug abuser patients, in particularly when emergency conditions occur.

A Rare Cause of Juvenile Stroke: Extracranial Carotid Artery Aneurysm with Venous Complete Reconstruction of the Carotid Bifurcation

Extracranial carotid artery aneurysms (ECAA) are a rare cause of embolic stroke. The underlying etiology is variable, with atherosclerosis being the most common entity in older subjects. Several treatments have been developed over the last 20 years, but the preferred method remains unknown. Notwithstanding the widespread use of endovascular techniques, surgical reconstruction by means of a bifurcated venous bypass graft should be applied in younger patients. In this way, it is possible to avoid major concerns about the development of long-term intrastent restenosis, and also to spare the external carotid artery which represents the main branch for the ipsilateral cerebral and facial perfusion. We propose ECAA resection and interposition of the inverted great saphenous vein to both the internal and external carotid artery by means the use of a tributary, i.e., the Giacomini vein.