Computational fluid-structure interaction analysis of the end-to-side radio-cephalic arteriovenous fistula.

BACKGROUND AND OBJECTIVE: In the current work, we present a descriptive fluid-structure interaction computational study of the end-to-side radio-cephalic arteriovenous fistula. This allows us to account for the different thicknesses and elastic properties of the radial artery and cephalic vein. METHODS: The core of the work consists in simulating different arteriovenous fistula configurations obtained by virtually varying the anastomosis angle, i.e. the angle between the end of the cephalic vein and the side of the radial artery. Since the aim of the work is to understand the blood dynamics in the very first days after the surgical intervention, the radial artery is considered stiffer and thicker than the cephalic vein. RESULTS: Our results demonstrate that both the diameter of the cephalic vein and the anastomosis angle play a crucial role to obtain a blood dynamics without re-circulation regions that could prevent fistula failure. CONCLUSIONS: When an anastomosis angle close to the perpendicular direction with respect to the radial artery is combined with a large diameter of the cephalic vein, the recirculation regions and the low Wall Shear Stress (WSS) zones are reduced. Conversely, from a structural point of view, a low anastomosis angle with a large diameter of the cephalic vein reduces the mechanical stress acting on the vessel walls.

Safety and feasibility of emergency robot-assisted transabdominal preperitoneal repair for the treatment of incarcerated inguinal hernia: A retrospective study.

BACKGROUND: Few studies assessed robotic in emergency setting and no solid evidence was demonstrated. The aim of this study was to evaluate the feasibility and safety of robot-assisted transabdominal preperitoneal (R-TAPP) repair for the treatment of incarcerated inguinal hernia. METHODS: We retrospectively searched from a prospectively maintained database patients who underwent R-TAPP or open surgery for incarcerated inguinal hernias from January 2018 to March 2023. The primary endpoint was to assess safety and feasibility of the R-TAPP compared to the standard approach. For eligible patients, data was extracted and analyzed using a propensity score-matching (PSM). RESULTS: Thirty-four patients were retrieved from our database, 15 underwent R-TAPP, while 19 underwent open surgery. Mean age was 73.1 ± 14.6 years, 30 patients (88.2%) were male and mean BMI was 23.5 ± 3.2 kg/m2. No intraoperative complication occurred. Three cases requiring small bowel resection were all in the open surgery group (p = 0.112). The operative time was 108 ± 31 min versus 112 ± 31 min in the R-TAPP and open surgery groups (p = 0.716). Seven postoperative complications occurred, only one classified as severe was in the open surgery group. The length of hospital stay was 2.9 ± 1.8 in the R-TAPP versus 4.2 ± 2.3 min in the open surgery group (p = 0.077). PSM analysis showed similar postoperative outcomes and costs in both groups. CONCLUSIONS: Despite its limitations, our study appears to endorse the safety and feasibility of the robotic-assisted treatment for incarcerated inguinal hernia. This approach yielded comparable results to open surgery, albeit in a limited number of patients, suggesting it might be a viable alternative.

Impact of Multidisciplinary Team Meetings on Decision Making in Vascular Surgery: A Prospective Observational Study.

OBJECTIVE: This cohort study aimed to prospectively determine the impact of multidisciplinary team meetings (MDTs) on treatment plans in vascular patients. METHODS: The weekly MDT at the institution consisted of a structured discussion of vascular cases in the presence of at least one representative of each specialty from vascular surgery, angiology, and interventional radiology. Participants were asked to examine the cases entered on the digital MDT platform and to fill in forms with a detailed open text treatment recommendation for each patient. Individual recommendations were compared with the final MDT decision, which was based on a shared decision after discussion of clinical and radiological data. The primary endpoint was the agreement rate. The rate of decision implementation was determined to verify the adherence to MDT recommendations. RESULTS: Four hundred consecutive case discussions in 367 patients between November 2019 and March 2021 were included, excluding patients needing urgent treatment, yielding MDT discussion in 88.5% of carotid artery cases, 83% of aorto-iliac cases, and 51.7% of peripheral arterial cases, which included 56.9% of the chronic limb threatening ischaemia cases. The overall average agreement rate was 71% ± 41%. Analysis according to the specialty of the attending physician showed agreement rates of 82% ± 30% for senior vascular surgeons, 62% ± 44% for junior vascular surgeons, 71% ± 43% for interventional radiologists, 58% ± 50% for angiologists (p < .001), and 75% ± 38% considering only senior practitioners. The inter-rater agreement, resulted in kappa coefficients of 0.60 - 0.68 for senior vascular surgeons, 0.29 - 0.31 for junior vascular surgeons, 0.39 - 0.52 for interventional radiologists, and 0.25 for angiologists. The MDT treatment decision was implemented in 353 (96.2%) cases. CONCLUSION: The impact of MDT discussion on treatment recommendations and the adherence to MDT recommendations were significant and in line with results reported from other specialties.

SOFA Score as a Reliable Tool to Detect High Risk for Venous Thrombosis in Patients With Critical Stage SARS-CoV-2.

Background: Severe acute respiratory syndrome from coronavirus-2 (SARS-CoV-2) has been associated with an increased risk of venous thromboembolism (VTE). Different anticoagulation protocols have been applied in several studies in the absence of clear evidence. A reliable deep venous thrombosis (DVT) indicator in critical patients with SARS-CoV-2 could guide the anticoagulation treatment; however, it has not yet been identified, and clinical applicability of the most common markers is debatable. The aim of our study was to determine the actual incidence of DVT in critically ill SARS-CoV-2 patients and to find a reliable tool to identify patients who might benefit from therapeutic-intensity anticoagulation. Methods: From March 1, 2020 to May 31, 2020, all patients admitted to the intensive care unit (ICU) for SARS-CoV-2 at Ospedale Regionale di Locarno, Locarno, Switzerland, were prospectively enrolled and screened daily with ultrasound for DVT. Following international consensus, a higher-intensity thromboprophylaxis was administered to all patients who were not at increased risk for bleeding. Sepsis-induced coagulopathy (SIC) and sequential organ failure assessment (SOFA) scores were calculated and time-to-DVT event in a COX proportional-hazard regression model was performed. A receiver operating characteristic (ROC) curve was used to determine sensitivity and specificity and the Youden's Index to establish the best threshold. Results: A total of 96 patients were enrolled. Deep venous thrombosis was detected in 37% of patients. Sepsis-induced coagulopathy and SOFA scores were both correlated to DVT. A SIC score of 1 vs. ≥2 showed a close association with DVT, with sensitivity, specificity, and positive and negative predictive values of 90.0, 48.1, and 49.1, and 89.7%, respectively. Most significantly though, a SOFA score of 1 or 2 points was shown to be the most accurate value in predicting the absence of DVT, indicating no need for therapeutic-intensity anticoagulation. Its sensitivity, specificity, and positive and negative predictive values were 87.9, 100, and 100, and 93.7%, respectively. The D-dimer test showed lower sensitivity and specificity whereas platelet count and aPTT were not found to be correlated to DVT. Conclusions: Patients with SOFA scores of 1 or 2 are at low risk of developing DVT and do not require therapeutic-intensity anticoagulation. Conversely, patients with scores ≥3 are at high risk of developing DVT.

Two-step treatment of dysphagia lusoria: robotic-assisted resection of aberrant right subclavian artery following aortic debranching.

A 69-year-old female suffering from severe dysphagia due to an aberrant right subclavian artery was treated with a two-step approach. A right carotid-subclavian bypass was followed 2 weeks later by a robotic-assisted thoracoscopic resection of the aberrant right subclavian artery. The postoperative course was uneventful, and the patient immediately recovered from her dysphagia. In our case, the robotic-assisted technology offered major advantages and, based on our experience, may be useful in the treatment of this rare disease.

Computational Analysis of Turbulent Hemodynamics in Radiocephalic Arteriovenous Fistulas to Determine the Best Anastomotic Angles.

BACKGROUND: Hemodynamics has been known to play a major role in the development of intimal hyperplasia leading to arteriovenous fistula failure. The goal of our study is to investigate the influence of different angles of side-to-end radiocephalic anastomosis on the hemodynamic parameters that promote intimal dysfunction and therefore intimal hyperplasia. METHODS: Realistic three-dimensional meshes were reconstructed using ultrasound measurements from distal side-to-end radiocephalic fistulas. The velocity at the proximal and distal radial inflows and at specific locations along the anastomosis and cephalic vein was measured through duplex ultrasound performed by a single examiner. A computational parametric study, virtually changing the inner angle of anastomosis, was performed. For this purpose, we used advanced computational models that include suitable tools to capture the pulsatile and turbulent nature of the blood flow found in arteriovenous fistulas. The results were analyzed in terms of velocity fields, wall shear stress distribution, and oscillatory shear index. RESULTS: Results show that the regions with high oscillatory shear index, which are more prone to the development of hyperplasia, are greater and progressively shift toward the anastomosis area and the proximal vein segment with the decrease of the inner angle of anastomosis. These results are specific to distal radiocephalic fistulas because they are subject to proximal and distal radial inflow. CONCLUSIONS: The results of this study show that inner anastomosis angles approaching 60-70° seem to yield the best hemodynamic conditions for maturation and long-term patency of distal radiocephalic fistulas. Inner angles greater than 90°, representing the smooth loop technique, did not show a clear hemodynamic advantage.

Outcome of Tubular Aortoaortic Endografts in Infrarenal Aneurysmal Disease and Penetrating Abdominal Aortic Ulcers-a Long-Term Follow-up.

BACKGROUND: We describe the long-term follow-up of patients treated for infrarenal abdominal aortic aneurysms and penetrating ulcers by placement of tubular aortic endografts at our institution from 2010 to present. METHODS: This is a retrospective study using clinical data of patients treated from 2010 to present by placement of either a single aortic tubular endograft or by two overlapping endografts, using the "trombone technique." Aortic dimensions were measured from the preoperative computed tomography scans using three-dimensional reconstruction. The primary outcome was aortic reintervention. Secondary outcomes were aorta-related mortality, endoleaks, and postoperative complications. RESULTS: Twenty-eight patients were identified. Nine patients were treated for saccular aneurysms, and nineteen patients presented with penetrating aortic ulcers. The median follow-up was 31 months (range: 4-99). Twenty patients were treated with a single tubular device, while eight patients were treated using two overlapping devices. Aortic reintervention occurred in four patients (14.3%), all were treated initially with a single device. No aortic mortality occurred during follow-up. No aneurysm ruptures occurred. Four patients died during follow-up of unrelated causes. Endoleaks occurred in ten patients (35%). Five endoleaks were of type I (17.8%), of which three were of distal type (10.7%). Five endoleaks were of type II (17.8%). Shorter distal landing zones than 20 mm were present in two of the cases with a distal type I endoleak (P = 0.0232). Postoperative complications occurred in three (10.7%) patients including one myocardial infarction and two wound complications from a surgical cut down in the groin. CONCLUSIONS: The technique shows an acceptable postoperative complication rate but is characterized by high rate of occurrence of type I endoleaks and aortic reintervention in our series. Endovascular techniques using tubular endografts should be limited to cases with long proximal and distal sealing zones. The trombone technique seems preferable.

Assessing the Disturbed Flow and the Transition to Turbulence in the Arteriovenous Fistula.

The arteriovenous fistula (AVF) is the main form of vascular access for hemodialysis patients, but its maintenance is very challenging. Its failure is mainly related to intimal hyperplasia (IH), leading to stenosis. The aim of this work was twofold: (i) to perform a computational study for the comparison of the disturbed blood dynamics in different configurations of AVF and (ii) to assess the amount of transition to turbulence developed by the specific geometric configuration of AVF. For this aim, we reconstructed realistic three-dimensional (3D) geometries of two patients with a side-to-end AVF, performing a parametric study by changing the angle of incidence at the anastomosis. We solved the incompressible Navier-Stokes equations modeling the blood as an incompressible and Newtonian fluid. Large eddy simulations (LES) were considered to capture the transition to turbulence developed at the anastomosis. The values of prescribed boundary conditions are obtained from clinical echo-color Doppler (ECD) measurements. To assess the disturbed flow, we considered hemodynamic quantities such as the velocity field, the pressure distribution, and wall shear stresses (WSS) derived quantities, whereas to quantify the transition to turbulence, we computed the standard deviation of the velocity field among different heartbeats and the turbulent kinetic energy.

Filter-Associated Inferior Vena Cava Thrombosis with Duodenal Perforation: Case Report and Literature Review.

BACKGROUND: The aim of this article is to report a case of filter-associated inferior vena cava (IVC) thrombosis with perforation of the duodenum and penetration of a vertebral body by the filter struts. CASE REPORT: A 37-year-old woman with a medical history of Behcet's disease treated with corticosteroids underwent placement of a retrievable IVC filter because of recurrent iliofemoral venous thrombosis regardless of therapeutic levels of anticoagulation. Despite a correct positioning of the filter, the second follow-up computed tomography scan, performed at 1 year, showed a complete thrombosis of the infrarenal IVC segment, with perforation of the vessel wall by the filter struts and penetration in the duodenum. The patient remained asymptomatic. Open surgical removal of the filter with resection of the affected vena cava without vascular reconstruction was planned. The operation was performed under general anesthesia, surgical exposure was performed through a small midline laparotomy, and a duodenal Kocher maneuver was then performed to expose the IVC. The filter struts were found to have completely passed the cava wall in multiple directions. 2 struts penetrated through the duodenal serosa and 1 strut was embedded in the L3 periosteum. The IVC filter was successfully removed en bloc with the segment of the thrombosed and retracted IVC. The stumps were closed with 3-0 running polypropylene sutures and the duodenal lesions were closed with vicryl seromuscular sutures. No vascular reconstruction was necessary due to the marked development of collateral venous circulation. The patient was discharged home on postoperative day 6 and is doing well 6 months after surgery. CONCLUSIONS: Patients with IVC penetration of filter struts are usually asymptomatic, as was our patient. However, a high level of clinical suspicion for perforation should be maintained when facing nonspecific abdominal or back pain, and in episodes of gastrointestinal bleeding in patients with an IVC filter. We recommend that patients with implanted IVC filters, even those who are asymptomatic, should receive regular imaging follow-up, and retrievable filters should be removed as soon as they are no longer needed.

Ultrasound screening for abdominal aortic aneurysms.

QUESTIONS UNDER STUDY: This pilot study aimed to assess the feasibility, acceptance and costs of an ultrasound scan screening programme for abdominal aortic aneurysms (AAA) in the elderly male population resident in Canton Ticino, Switzerland. METHODS: The target population were male patients aged 65-80 years who attended the outpatient clinics of the Lugano Regional Hospital in 2013. The patients showing interest were contacted by phone to verify their eligibility and fix the appointment for the ultrasound scan of the abdominal aorta. Patients with recent examinations suitable for AAA detection were excluded. Aneurysm was defined as an abdominal aorta with sagittal and/or axial diameter  30 mm. Patients' characteristics and study results were presented as descriptive statistics. The chi-squared test was used to compare categorical variables with p <0.05 as a statistical significance threshold. RESULTS: 1634 patients received the screening information leaflet and 745 (45.6%) underwent the ultrasound scan. Among the 1091 eligible patients, the acceptance rate was 68.3%. A previously unknown AAA was diagnosed in 31 patients (4.2%, 95% confidence interval 2.8-5.9%). Age and area of residence had a statistically significant impact on patient's acceptance rate (p <0.05). The mean cost per screened patient was CHF 88. CONCLUSIONS: AAA screening of male patients aged 65-80 years is feasible with limited financial and organisational effort. Adherence might be improved by a larger community-based programme and involvement of general practitioners.

Double osteotomy of mandibula in the treatment of carotid body tumors with skull base extension.

We report two patients with a carotid body paraganglioma that extended to the skull base, a position that is surgically inaccessible by means of a traditional lateral cervical approach. In both patients we were able to remove the lesion by performing a double mandibular osteotomy. Both patients underwent preoperative embolization to reduce the mass. In our experience, this approach has allowed a safe radical excision of exceptionally high lesions with only minor permanent nerve damage. In our opinion this advantage definitely outweighs the consequences of the increased invasiveness of this technique.