Optimal control problem arising in mathematical modeling of cerebral vascular pathology embolization.

Arteriovenous malformation (AVM) of the brain is a congenital vascular abnormality, in which the arterial and venous blood pools are intertwined and directly connected. This dangerous disease causes a high risk of intracranial hemorrhage and disrupts brain functioning. The preferred method of AVM treating is embolization, which is the endovascular filling of abnormal AVM vessels with a special embolic agent. Despite the fact that this method is widely used in neurosurgery, in some cases its use is accompanied by perioperative AVM vessels rupture. In this regard, the aim of this work is to study the optimal scenarios for multi-stage AVM embolization from the effectiveness and safety of the procedure point of view. Mathematically, the joint movement of blood and embolic agent in the AVM body is described on the basis of a one-dimensional two-phase filtration model, which takes into account the redistribution of blood to surrounding healthy vessels. For the numerical solution of the resulting integro-differential system of equations, a monotonic modification of the CABARET scheme is used. To find optimal embolization scenarios, the optimal control problem with phase constraints arising from medicine is formulated. A modified particle swarm optimization method is used to solve this problem numerically. This technique is used to obtain optimal embolization scenarios on the basis of real patients clinical data collected during neurosurgical operations.

Retroperitoneal teratomas in children: a single institution experience.

PURPOSE: Retroperitoneal teratomas (RPTs) are rare in infants. We report our experience of treating pediatric patients with RPTs over many years at a single institution, with the aim of developing a safe and secure operative strategy for RPTs in infants. METHODS: We reviewed the medical records of patients who underwent treatment for RPTs in our institution between April, 1984 and December, 2017, to analyze their background and clinical data. The diagnosis of RPT was confirmed histologically in all patients. RESULTS: The subjects of this retrospective analysis were 14 pediatric patients (female, n = 11; male, n = 4), ranging in age from 6 days to 12 years, 11 (73.3%) of whom were under 1 year of age. Complete surgical resection was performed in all patients. The tumor ruptured during surgery in four (26.7%) patients and perioperative vessel injuries occurred in six (40.0%) patients, resulting in nephrectomy in one (6.7%). Three (20.0%) patients suffered unilateral renal dysfunction as a surgical complication. Only one patient received postoperative chemotherapy. All patients were free of disease at the time of writing. CONCLUSION: Perioperative complications are not uncommon during surgery for RPTs, despite their benign nature. Preoperative imaging evaluation is important and operative management may be challenging. Because of the favorable prognosis and the frequency of adverse events in surgery, partial resection or split excision is sometimes unavoidable. Meticulous follow-up for recurrence is required for such patients.

Learning from mistakes when reporting urgent and emergency vascular studies.

The majority of out-of-hours cases relate to neurological, chest, and gastrointestinal pathologies with acute vascular cases being encountered less commonly. Trainees and exposure of non-vascular/interventional radiology (IR) consultants to angiographic imaging is often limited in working hours and this may lead to reporting on-call cases outside of normal daytime practice. In a recent local review, a number on-call vascular studies were found to contain a number of vascular-related discrepancies. Vascular reporting is a complex subspecialty, which comprises many clear diagnoses (large vessel occlusions, large vessel aneurysms, or dissections); however, also several subtle and complex abnormalities. These more subtle abnormalities, at times, require dedicated vascular specialist review to ensure subtle findings are communicated appropriately to the clinical team. The recent increased complexity of endovascular treatments and their complications has also provided further challenge for the non-specialist reporter. Similarly, improved imaging techniques have allowed for non-obvious but significant findings that may require urgent management, such as small aneurysms and dissection flaps. We will review a range of key vascular findings that demonstrate learning opportunities, particularly within the acute and on-call settings. These will include gastrointestinal haemorrhage, subtle aortic pathologies, head and neck vascular emergencies, small to mid-sized vessel injuries and imaging of post-procedural complications. Educational hints and tips will be provided to enable learning from mistakes encountered by trainees and non-vascular specialist radiologists in the on-call or urgent reporting settings, and these will be reviewed with reference to the literature.

Efficacy and Safety of Plastic Cannulae Compared with Metal Needles in the Initial Use of an Arteriovenous Fistulae in Incident Hemodialysis Patients: A Randomized Controlled Study.

INTRODUCTION: Successful cannulation of an arteriovenous fistula (AVF) is important in patients starting hemodialysis (HD). Metal needles have been used for decades, but the usefulness of plastic cannulae has recently been demonstrated as a new technique. METHODS: This was a prospective, randomized, open-label study of incident HD patients. Eligible patients were randomized into 2 groups in a 1:1 ratio (n = 45/group). Maturation of the AVF was confirmed using Doppler ultrasound prior to first needling, and 2 well-trained nurses implemented the AVF cannulation. The primary endpoint was the initial cannulation failure rate, defined as the failure of successful completion of 3 consecutive dialysis sessions. The secondary endpoints were time for hemostasis at the end of HD, degree of patients' pain, degree of cannulation difficulty felt by the nursing staffs, and achieving optimal HD adequacy. RESULTS: The mean elapsed time from AVF creation to the first cannulation was 48.1 ± 16.7 days. A total of 17 cases of cannulation failure occurred, and the failure risk tended to be higher in the metal needle group than the plastic cannula group (hazard ratio 2.6, 95% confidence interval 0.95-7.41) after adjusting for age, gender, comorbidities, and AVF location. The overall incidence of vessel injury was higher and time for hemostasis was significantly longer in the metal group than the plastic group. The use of plastic cannula was associated with a better HD adequacy compared to a metal needle. However, the patients' pain score (p = 0.004) and nursing staff's cannulation difficulty score (p = 0.084) were higher in the plastic group, emphasizing the great importance of practice using plastic cannulae. CONCLUSION: The vascular outcomes of plastic cannulae were much favorable compared to metal needles in incident HD patients. The use of plastic cannulae could be a new and innovative way to improve the quality of dialysis.

Contribution of PDGFRα-positive cells in maintenance and injury responses in mouse large vessels.

The maladaptive remodeling of vessel walls with neointima formation is a common feature of proliferative vascular diseases. It has been proposed that neointima formation is caused by the dedifferentiation of mature smooth muscle cells (SMCs). Recent evidence suggests that adventitial cells also participate in neointima formation; however, their cellular dynamics are not fully understood. In this study, we utilized a lineage tracing model of platelet-derived growth factor receptor alpha (PDGFRa) cells and examined cellular behavior during homeostasis and injury response. PDGFRa marked adventitial cells that were largely positive for Sca1 and a portion of medial SMCs, and both cell types were maintained for 2 years. Upon carotid artery ligation, PDGFRa-positive (+) cells were slowly recruited to the neointima and exhibited an immature SMC phenotype. In contrast, in a more severe wire denudation injury, PDGFRa+ cells were recruited to the neointima within 14 days and fully differentiated into SMCs. Under pressure overload induced by transverse aortic constriction, PDGFRa+ cells developed marked adventitial fibrosis. Taken together, our observations suggest that PDGFRa+ cells serve as a reservoir of adventitial cells and a subset of medial SMCs and underscore their context-dependent response to vascular injuries.

Suspension torture and its physical sequelae.

Suspension torture is one of the most common and widespread methods of torture. The objective of the study is to conduct a systematic literature review and produce an overview of suspension torture and its health implications, thus improving the diagnosis of suspension torture victims and documentation of their injuries. The review includes the prevalence, geographical distribution and description of variations of suspension torture. Physical sequelae like nerve injuries, e.g. brachial plexus injuries, scars, joint dislocation and possible causes of death will be described in detail. The results of the review are discussed resulting in recommendations on torture identification and documentation practices and possible future research questions.

Computer Simulation of Platelet Adhesion around Stent Struts in the Presence and Absence of Tissue Defects around Them.

AIM: To predict platelet accumulation around stent struts in the presence or absence of tissue defects around them. METHODS: Computer simulations were performed using virtual platelets implementing the function of the three membrane proteins: glycoprotein (GP) Ibα, GPIIb/IIIa, and GPVI. These platelets were perfused around the stent struts implanted into the vessel wall in the presence or absence of tissue defects around them using within the simulation platform. The number of platelets that adhered around stent struts was calculated by solving the blood flow using Navier-Stokes equation along with the adhesion of membrane protein modeled within the platform. RESULTS: Platelet accumulation around stent struts occurred mostly at the downstream region of the stent strut array. The majority of platelets adhered at the downstream of the first bend regardless of the tissue defect status. Platelet adhesion around stent struts occurred more rapidly in the presence of tissue defects. CONCLUSION: Computer simulation using virtual platelets suggested a higher rate of platelet adhesion in the presence of tissue defects around stent struts.

Macrophage TLR4 and PAR2 Signaling: Role in Regulating Vascular Inflammatory Injury and Repair.

Macrophages play a central role in dictating the tissue response to infection and orchestrating subsequent repair of the damage. In this context, macrophages residing in the lungs continuously sense and discriminate among a wide range of insults to initiate the immune responses important to host-defense. Inflammatory tissue injury also leads to activation of proteases, and thereby the coagulation pathway, to optimize injury and repair post-infection. However, long-lasting inflammatory triggers from macrophages can impair the lung's ability to recover from severe injury, leading to increased lung vascular permeability and neutrophilic injury, hallmarks of Acute Lung Injury (ALI). In this review, we discuss the roles of toll-like receptor 4 (TLR4) and protease activating receptor 2 (PAR2) expressed on the macrophage cell-surface in regulating lung vascular inflammatory signaling.

Design of a robot-assisted system for transforaminal percutaneous endoscopic lumbar surgeries: study protocol.

BACKGROUND: Transforaminal percutaneous endoscopic lumbar surgeries (PELS) for lumbar disc herniation and spinal stenosis are growing in popularity. However, there are some problems in the establishment of the working channel and foraminoplasty such as nerve and blood vessel injuries, more radiation exposure, and steeper learning curve. Rapid technological advancements have allowed robotic technology to assist surgeons in improving the accuracy and safety of surgeries. Therefore, the purpose of this study is to develop a robot-assisted system for transforaminal PELS, which can provide navigation and foraminoplasty. METHODS: The robot-assisted system consists of three systems: preoperative planning system, navigation system, and foraminoplasty system. In the preoperative planning system, 3D visualization of the surgical segment and surrounding tissues are realized using the multimodal image fusion technique of computed tomography and magnetic resonance imaging, and the working channel planning is carried out to reduce the risk for injury to vital blood vessels and nerves. In the navigation system, the robot can obtain visual perception ability from a visual receptor and automatically adjust the robotic platform and robot arm to the appropriate positions according to the patient's position and preoperative plan. In addition, the robot can automatically register the surgical levels through intraoperative fluoroscopy. After that, the robot will provide navigation using the 6 degree-of-freedom (DOF) robot arm according to the preoperative planning system and guide the surgeon to complete the establishment of the working channel. In the foraminoplasty system, according to the foraminoplasty planning in the preoperative planning system, the robot performs foraminoplasty automatically using the high speed burr at the end of the robot arm. The system can provide real-time feedback on the working status of the bur through multi-mode sensors such as multidimensional force, position, and acceleration. Finally, a prototype of the system is constructed and performance tests are conducted. DISCUSSION: Our study will develop a robot-assisted system to perform transforaminal PELS, and this robot-assisted system can also be used for other percutaneous endoscopic spinal surgeries such as interlaminar PELS and percutaneous endoscopic cervical and thoracic surgeries through further research. The development of this robot-assisted system can be of great significance. First, the robot can improve the accuracy and efficiency of endoscopic spinal surgeries. In addition, it can avoid multiple intraoperative fluoroscopies, minimize exposure to both patients and the surgical staff, shorten the operative time, and improve the learning curve of beginners, which is beneficial to the popularization of percutaneous endoscopic spinal surgeries.

Hemostasis vs. homeostasis: Platelets are essential for preserving vascular barrier function in the absence of injury or inflammation.

Platelets are best known for their vasoprotective responses to injury and inflammation. Here, we have asked whether they also support vascular integrity when neither injury nor inflammation is present. Changes in vascular barrier function in dermal and meningeal vessels were measured in real time in mouse models using the differential extravasation of fluorescent tracers as a biomarker. Severe thrombocytopenia produced by two distinct methods caused increased extravasation of 40-kDa dextran from capillaries and postcapillary venules but had no effect on extravasation of 70-kDa dextran or albumin. This reduction in barrier function required more than 4 h to emerge after thrombocytopenia was established, reverting to normal as the platelet count recovered. Barrier dysfunction was also observed in mice that lacked platelet-dense granules, dense granule secretion machinery, glycoprotein (GP) VI, or the GPVI signaling effector phospholipase C (PLC) γ2. It did not occur in mice lacking α-granules, C type lectin receptor-2 (CLEC-2), or protease activated receptor 4 (PAR4). Notably, although both meningeal and dermal vessels were affected, intracerebral vessels, which are known for their tighter junctions between endothelial cells, were not. Collectively, these observations 1) highlight a role for platelets in maintaining vascular homeostasis in the absence of injury or inflammation, 2) provide a sensitive biomarker for detecting changes in platelet-dependent barrier function, 3) identify which platelet processes are required, and 4) suggest that the absence of competent platelets causes changes in the vessel wall itself, accounting for the time required for dysfunction to emerge.

Knee Dislocations in the Morbidly Obese Patient.

Ultra-low-velocity knee dislocations are historically rare but increasingly common events. They occur most frequently in obese, morbidly obese, and super obese patients during everyday activities, but they can be as severe or more severe than high-velocity knee dislocations. Ultra-low-velocity knee dislocations frequently are associated with neurovascular injury and other complications. Diagnosis, early reduction, and identification and treatment of vascular injuries are critical to reducing the risk of limb ischemia and possibly amputation. Given the size of the limb, maintenance of reduction in these patients almost always requires external fixation. Although surgery on morbidly obese patients may be technically challenging, surgical reconstruction leads to improved subjective and objective results and is recommended.

Modeling Clot Formation of Shear-Injured Platelets in Flow by a Dissipative Particle Dynamics Method.

The regions with high non-physiological shear stresses (NPSS) are inevitable in blood-contacting medical devices (BCMDs) used for mechanically assisted circulatory support. NPSS can cause platelet activation and receptor shedding potentially resulting in the alteration of hemostatic function. In this study, we developed a dissipative particle dynamics model to characterize clot formation (platelet-collagen and inter-platelet adhesion) of NPSS-traumatized blood at a vascular injury site. A rectangular tube of 50 × 50 × 200 µm with an 8 × 8 µm collagen-coated area was modeled as a small blood vessel and perfusion with blood. Clot formation dynamics during perfusion was simulated. NPSS-traumatized blood was modeled to have more activated platelet and fewer adhesion receptors with weakened inter-platelet binding. Computational results showed that clots grew at a faster rate while the structure of the clots was less stable and collapsed more frequently for NPSS-traumatized blood compared with normal blood. The finding that NPSS-traumatized platelets could result in quicker but more easily breakable blood clots at injury sites may explain why increased risks of thrombotic and bleeding complications occurred concurrently in patients implanted with BCMDs.

Prospective study of 80 volar wounds of the hand and wrist: Correlations between clinical examination and intraoperative findings.

Hand and wrist volar wounds are a common cause of emergency room (ER) visits. These wounds are explored surgically in the operating room at most hospitals. The main objective of our study was to prospectively assess the correlation between clinical examination in the ER performed by a surgical resident and the tendon, vascular and/or nerve damage found during surgery in hand and wrist volar wounds. The second objective was to describe the lesions based on their mechanism, as well as their topography. Eighty patients from two hand surgery referral centers were included. Patients' past medical history was obtained, as well as records of their physical examination in the ER and description of lesions found during surgery. In 28% of wounds with a normal clinical examination, tendon, vascular or nerve damage was found on surgical exploration. Out of the cases that tested negative for tendon injury in the ER, 16% had partial tendon injury or digital tunnel wound discovered during surgery. Nerve damage was found during surgery in 12% of cases that had not been detected clinically preoperatively. Based on our findings, we recommend performing surgical exploration for all volar hand and wrist wounds in the operating room, as physical examination does not detect all tendons, vascular or nerve injuries.

Cadet Agustín Melgar and military peripheral vascular trauma approach during Chapultepec's Battle.

Trauma to peripheral vascular organ is a very frequent condition during military conflicts. Fortunately, comprehensive understanding of local and systemic pathophysiology, in addition to the development of innovative surgical techniques and technological advances, have improved the outcome regarding to survival and anatomic and functional conservation of the limbs. In this manuscript, we perform an historical and state of the art review related to the approach of the peripheral vascular trauma, on the basis of an heroical episode from the Mexico City's Campaign, during North American invasion 1846-1848: the defense of Chapultepec's Castle by cadet Agustin Melgar.

El trauma del órgano vascular periférico es una condición muy frecuente en los conflictos militares. Por fortuna, la comprensión integral de la fisiopatología local y sistémica, en adición al desarrollo de técnicas quirúrgicas innovadoras y avances tecnológicos, ha mejorado el pronóstico relativo a la sobrevida y la conservación anatómica y funcional de las extremidades. En este trabajo se hace una revisión histórica y del estado actual del abordaje del trauma vascular periférico, sobre la base de un episodio heroico de la Campaña por la Ciudad de México durante la invasión norteamericana de 1846-1848: la defensa del Castillo de Chapultepec por el cadete Agustín Melgar.

Optical coherence tomography imaging after endovascular thrombectomy: a novel method for evaluating vascular injury in a swine model.

OBJECTIVE: Although studies have shown that some degree of iatrogenic endothelial injury occurs during endovascular thrombectomy (EVT), the clinical significance of such injury is uncertain. Furthermore, it is likely that iatrogenic effects such as endothelial denudation, intimal dissection, and tunica media edema will have varying clinical implications. The purpose of this study was to assess the feasibility of endovascular optical coherence tomography (OCT) in quantifying vessel injury in real time after EVT, correlate vessel injury with histological findings, and perform imaging at varying time intervals after EVT to assess the impact of prolonged direct exposure of the vessel to the thrombus. METHODS: Yorkshire swine weighing 35-40 kg were selected for use as the animal model, with a total of 9 vessels from 3 swine examined. Thrombectomy was performed using a second-generation stent retriever 1, 3, and 6 hours after thrombus deposition. The presence and degree of denudation of the endothelium, detachment and separation of the layers of the tunic media, hemorrhage within the media, dissection of the vessels, and thrombus within the lumina were assessed using OCT images acquired immediately after EVT. Bland-Altman analysis indicated that these OCT findings were correlated with postmortem histological findings. RESULTS: OCT image acquisition was technically successful in all cases. Endothelial denudation was present in 65% ± 16%, 87% ± 8%, and 93% ± 7% of the vessel surface 1, 3, and 6 hours, respectively, after thrombus deposition and subsequent EVT. Residual intraluminal thrombus was present in vessels at all time intervals despite complete angiographic revascularization. Bland-Altman plots showed good agreement between OCT and histological analysis with respect to the degree of endothelial denudation and elevation, separation of the tunica media, and hemorrhage within the media. OCT appears to be more specific than histological analysis in detecting endothelial elevation. CONCLUSIONS: OCT is a feasible method that can be used to assess vascular injury after EVT with histological accuracy. Varying degrees of vessel injury occur after EVT, and residual luminal thrombus can be present despite complete angiographic revascularization.

Arterial lesions in osteoarticular trauma of the lower limbs.

OBJECTIVE: To evaluate in-hospital mortality and limb salvage of a series of patients presenting with arterial injury of the lower limbs complicating an osteoarticular trauma, and to determine any preoperative predictive factors of limb salvage. METHODS: Data of consecutive patients treated between 01/2007 and 12/2017 were retrospectively analyzed. Primary outcomes were in-hospital mortality and limb salvage. Multivariate analysis was performed to assess any variable that could affect limb salvage. P values <0.05 were considered statistically significant. RESULTS: The postoperative course, death occurred in 2 patients Lower limb amputation was performed in 13 cases (15.6%). The main factors predicting limb amputation were the timing of staged surgery, in particular when bone stabilization was performed first (P<0.001), and a delay Data concerning 74 patients with 83 traumatized lower limbs were analyzed. Most vascular lesions were located at the popliteal artery (47, 63.5%). Surgical bone stabilization was performed as a first step in 45 patients (60.8% of cases), followed by a delayed arterial repair. The median time to revascularization was 14.3 hours (range from 2 hours to 6 days). In 29 patients (39.2%) vascular repair and bone stabilization were performed simultaneously. During to limb revascularization longer than 6 hours (P<0.001). The location of injury at the popliteal artery (P=0.005), the presence of infection (P<0.001), and the severe ischemic signs at presentation (P=0.001) also were factors associated with amputation. CONCLUSIONS: The timing of staged surgical repair and the revascularization delay were the main predictor factors of limb salvage. KEY WORDS: Osteoarticular trauma, Vascular injury, Limb salvage, Orthopedic trauma.