Trends and Factors Associated With Peripheral Vascular Interventions for the Treatment of Claudication From 2011 to 2022: A National Medicare Cohort Study.

BACKGROUND: Previous cross-sectional studies have identified wide practice pattern variations in the use of peripheral vascular interventions (PVIs) for the treatment of claudication. However, there are limited data on longitudinal practice patterns. We aimed to describe the temporal trends and charges associated with PVI use for claudication over the past 12 years in the United States. METHODS AND RESULTS: We conducted a retrospective analysis using 100% Medicare fee-for-service claims data to identify all patients who underwent a PVI for claudication between January 2011 and December 2022. We evaluated the trends in utilization and Medicare-allowed charges of PVI according to anatomic level, procedure type, and intervention settings using generalized linear models. Multinomial logistic regressions were used to evaluate factors associated with different levels and types of PVI. We identified 599 197 PVIs performed for claudication. The proportional use of tibial PVI increased 1.0% per year, and atherectomy increased by 1.6% per year over the study period. The proportion of PVIs performed in ambulatory surgical centers/office-based laboratories grew at 4% per year from 12.4% in 2011 to 55.7% in 2022. Total Medicare-allowed charges increased by $11 980 035 USD/year. Multinomial logistic regression identified significant associations between race and ethnicity and treatment setting with use of both atherectomy and tibial PVI. CONCLUSIONS: The use of tibial PVI and atherectomy for the treatment of claudication has increased dramatically in in ambulatory surgical center/office-based laboratory settings, non-White patients, and resulting in a significant increase in health care charges. There is a critical need to improve the delivery of value-based care for the treatment of claudication.

Comparison of Contralateral vs Ipsilateral Vein Graft for Traumatic Vascular Injury Repair: A Cohort From PROOVIT.

Traumatic injury leading to arterial damage has traditionally been repaired using autologous vein graft from the contralateral limb. This often requires a secondary surgical site and the potential of prolonged operative time for patients. We sought to assess the use of ipsilateral vs contralateral vein grafts in patients who experienced traumatic extremity vascular injury. A multicenter database was queried to identify arterial injuries requiring operative intervention with vein grafting. The primary outcome of interest was need for operative reintervention. Secondary outcomes included risk of thrombosis, infection, and intensive care unit length of stay. 358 patients (320 contralateral and 38 ipsilateral) were included in the analysis. The ipsilateral vein cohort did not display a statistically significant decrease in need for reoperation when compared to the contralateral group (11% vs 23%; OR 0.41, 95% CI -0.07-1.3; P = .14). Contralateral repair was associated with longer median intensive care unit (ICU) LOS (4.3 vs 3.1 days; P < .01).

Utility of motor-evoked potentials in contemporary open thoracoabdominal aortic repair.

OBJECTIVE: Paraplegia remains one of the major complications of contemporary open thoracoabdominal aortic aneurysm (TAAA) repair. Intraoperative motor-evoked potentials (MEPs) act as a surrogate measure for spinal cord homeostasis. The purpose of this study was to evaluate the results of intraoperative neuromonitoring in contemporary TAAA repair and its association with postoperative spinal cord ischemia (SCI). METHODS: Patients who underwent open type 2 or 3 TAAA or completion aortic repair using intraoperative neuromonitoring were identified between May 2006 and November 2023. Patient demographics, comorbidities, indication for the procedure, procedural details, and outcomes were recorded. The groups were divided based on type of repair, and univariate statistics were then used to evaluate the association of these metrics vs the type of repair. RESULTS: Seventy-nine patients underwent open type 2 (N = 41) and 3 (N = 23) TAAA and completion aortic (N = 15; open in 14 and endovascular in 1) repairs by a single surgeon. The cohort was predominantly male (N = 48, 60.8%) with a mean age of 52.5 ± 16.2 years. There was a high incidence of hypertension (N = 53, 67.1%), smoking history (N = 42, 53.1%), and connective tissue disorders (N = 37, 46.8%). Operative indications included dissection-related (N = 50, 63.3%) and degenerative (N = 26, 32.9%) TAAA and dissection-related malperfusion (N = 3, 3.8%). Left heart bypass was often (N = 73, 92.4%) used for distal aortic perfusion, and cerebrospinal fluid drainage (N = 77, 97.5%) was a common adjunct. MEPs were classified as no change (N = 43, 54.4%), reversible change (N = 26, 32.9%), irreversible change (N = 4, 5.1%), and unreliable (N = 6, 7.6%). MEP changes were predominantly bilateral (N = 70, 88.6%) and occurred most often during repair of the abdominal aortic segment (N = 13, 16.5%). The median number of replaced vertebral levels was associated with MEP changes (P = .013). SCI was only observed in repairs greater than 6 replaced vertebral levels with an overall frequency of 17.7%. It was most prevalent in completion aortic repairs (26.7%). Immediate and delayed SCI occurred in 10.1% and 7.6% of patients, respectively; it was most commonly (71.8%) reversible. Permanent paraplegia occurred in four patients (5.1%), with equal immediate and delayed onsets. MEPs demonstrated poor sensitivity (53.9%) and specificity (62.3%) for SCI; however, there was a high negative predictive value (86.4%) in this population. In-hospital mortality occurred in five (6.3%) patients. CONCLUSIONS: No changes in intraoperative MEPs are highly predictive of spinal cord homeostasis. The number of replaced vertebral levels and previous aortic repair should guide intraoperative neuroprotective measures including intercostal reimplantation and should take precedence over intraoperative monitoring, especially when MEP changes occur.

Technical and analytical approach to biventricular pressure-volume loops in swine including a completely endovascular, percutaneous closed-chest large animal model.

Pressure-volume (PV) loop analysis is a sophisticated invasive approach to quantifying load-dependent and independent measures of cardiac function. Biventricular (BV) PV loops allow left and right ventricular function to be quantified simultaneously and independently, which is important for conditions and certain physiologic states, such as ventricular decoupling or acute physiologic changes. BV PV loops can be performed in an entirely endovascular, percutaneous, and closed-chest setting. This technique is helpful in a survival animal model, as a percutaneous monitoring system during endovascular device experiments, or in cases where chest wall compliance is being tested or may be a confounder. In this article, we describe the end-to-end implementation of a completely endovascular, totally percutaneous, and closed-chest large animal model to obtain contemporaneous BV PV loops in 40 to 70 kg swine. We describe the associated surgical and technical challenges and our solutions to obtaining endovascular BV PV loops, closed-chest cardiac output, and stroke volume (including validation of the correction factor necessary for thermodilution), as well as how to perform endovascular inferior vena cava occlusion in this swine model. We also include techniques for data acquisition and analysis that are required for this method.

Raising Systemic Blood Pressure to Delay Irreversible Intestinal Ischemia in a Swine Model of Proximal Superior Mesenteric ArteryOcclusion.

INTRODUCTION: Acute proximal superior mesenteric artery (SMA) occlusion is highly lethal, and adjuncts are needed to mitigate ischemic injury until definitive therapy. We hypothesized that raising mean arterial pressure (MAP) >90 mmHg with norepinephrine may delay irreversible bowel ischemia by increasing gastroduodenal artery (GDA) flow despite possible pressor-induced vasospasm. METHODS: 12 anesthetized swine underwent laparotomy, GDA flow probe placement, and proximal SMA exposure and clamping. Animals were randomized between conventional therapy (CT) versus targeted MAP >90 mmHg (MAP push; MP) where norepinephrine was titrated after 45 min of SMA occlusion. Animals were followed until bowel death or 4 h. Kaplan-Meier bowel survival, mean normalized GDA flow, and histology were compared. RESULTS: 12 swine (mean 57.8 ± 7.6 kgs) were included, six per group. Baseline weight, HR, MAP and GDA flows were not different. Within 5 min following SMA clamping, all 12 animals had an increase in MAP without other intervention from 81.7 to 105.5 mmHg (29.1%, P < 0.01) with a concomitant 74.9% increase in GDA flow as compared to baseline (P < 0.01). Beyond 45 min postclamp, MAP was greater in the MP group as intended, as were GDA flows. Median time to irreversibly ischemic bowel was 31% longer for MAP push animals (CT: 178 versus MP: 233 min, P = 0.006), Hazard Ratio of CT 8.85 (95% CI: 1.86-42.06); 3/6 MP animals versus 0/6 CT animals with bowel survived to predetermined end point. CONCLUSIONS: In this swine model of acute complete proximal SMA occlusion, increasing MAP >90 mmHg with norepinephrine was associated with an increase in macrovascular blood flow through the GDA and bowel survival. Norepinephrine was not associated with worse bowel survival and a MAP push may increase the time window where ischemic bowel can be salvaged.

Automatic 1-year follow-up appointment creation and reminders can improve long-term follow-up after carotid revascularization.

BACKGROUND: Long-term follow-up (LTFU) following carotid revascularization is important for post-surgical care, stroke risk optimization and post-market surveillance of new technologies. METHODS: We instituted a quality improvement project to improve LTFU rates for carotid revascularizations (primary outcome) by scheduling perioperative and one-year follow-up appointments at time of surgery discharge. A temporal trends analysis (Q1 2019 through Q1 2022), multivariable regression, and interrupted time series (ITS) were performed to compare pre-post intervention LTFU rates. RESULTS: 269 consecutive patients were included (151 pre-intervention, 118 post-intervention; mean 71 â€‹± â€‹12 years-old, 39% female, 77% White). The overall LTFU rate improved (64.9%-78.8%; P â€‹= â€‹0.013) after the intervention. After controlling for patient factors, procedures performed after the intervention were associated with increased odds of being seen for 1-year follow-up (OR: 2.2 95%CI: 1.2-4.0). Quarterly ITS analysis corroborated this relationship (P â€‹= â€‹0.01). CONCLUSIONS: Time-of-surgery appointment creation and automated patient reminders can improve LTFU rates following carotid revascularizations.

Mature artificial intelligence- and machine learning-enabled medical tools impacting vascular surgical care: A scoping review of late-stage, US Food and Drug Administration-approved or cleared technologies relevant to vascular surgeons.

Artificial intelligence and machine learning (AI/ML)-enabled tools are shifting from theoretical or research-only applications to mature, clinically useful tools. The goal of this article was to provide a scoping review of the most mature AI/ML-enabled technologies reviewed and cleared by the US Food and Drug Administration relevant to the field of vascular surgery. Despite decades of slow progress, this landscape is now evolving rapidly, with more than 100 AI/ML-powered tools being approved by the US Food and Drug Administration each year. Within the field of vascular surgery specifically, this review identified 17 companies with mature technologies that have at least one US Food and Drug Administration clearance, all occurring between 2016 and 2022. The maturation of these technologies appears to be accelerating, with improving regulatory clarity and clinical uptake. The early AI/ML-powered devices extend or amplify clinically entrenched platform technologies and tend to be focused on the diagnosis or evaluation of time-sensitive, clinically important pathologies (eg, reading Digital Imaging and Communications in Medicine-compliant computed tomography images to identify pulmonary embolism), or when physician efficiency or time savings is improved (eg, preoperative planning and intraoperative guidance). The majority (>75%) of these technologies are at the intersection of radiology and vascular surgery. It is becoming increasingly important that the contemporary vascular surgeon understands this shifting paradigm, as these once-nascent technologies are finally maturing and will be encountered with increasingly regularity in daily clinical practice.

Current Management of Intermittent Claudication.

Peripheral artery disease (PAD) is a common condition representing a spectrum of clinical disease. Intermittent claudication, which is defined as PAD with lower extremity pain on exertion that resolves with rest, represents mild-to-moderate PAD. Intermittent claudication is associated with a low risk of limb loss long-term but is a significant marker of systemic cardiovascular risk. Here, we describe the workup, diagnosis, and management of intermittent claudication.

Corrigendum: Implementation of a patient-centered remote wound monitoring system for management of diabetic foot ulcers.

[This corrects the article DOI: 10.3389/fendo.2023.1157518.].

Endovascular stenting techniques for blunt carotid injury.

OBJECTIVES: While methods of endovascular carotid artery stenting have improved over time, concerns surrounding the safety and efficacy of stenting for blunt carotid injury (BCI) remain. This study aims to present our approach to carotid artery stenting (CAS) by incorporating new technologies such as flow-diverting stents and circuits. METHODS: There is no robust evidence to support routine carotid artery stenting; however, there are several therapeutic options and approaches for treating BCI that currently require an individualized approach. Endovascular stenting and specific stent selection are largely dictated by the disease process the surgeon intends to treat. We will discuss patient selection, medical management, and the most common revascularization techniques, including transfemoral stenting, trans-carotid arterial revascularization using flow reversal, and stent-assisting coiling. RESULTS: It must be stressed that endovascular intervention is not an alternative to or preclusive of antithrombotic or anticoagulant therapy. In the setting of BCI, transfemoral CAS is most appropriate in patients who are symptomatic, have a rapidly progressing or large lesion, and do not have a soft thrombus present due to risk of embolism. Unlike transfemoral CAS, TCAR offers an elegant solution for embolic protection when patients have a soft thrombus present. In the case of a large pseudoaneurysm, we perform stent-assisted coiling. CONCLUSIONS: We practice selective endovascular intervention, stenting lesions that are flow-limiting or have large or rapidly expanding pseudoaneurysms, and only in patients for whom anticoagulation and antiplatelet agents are not contraindicated. As technology and investigation progress, the concerns regarding the safety and the role of endovascular intervention in the treatment of BCI will be more clearly defined.

Acute management of mesenteric emergencies: Tailoring the solution to the problem.

Acute mesenteric ischemia (AMI) constitutes a life-threatening problem that can result in death, multiorgan failure, and severe nutritional disability. Although AMI is a rare cause of acute abdominal emergencies, ranging between 1 and 2 individuals per 10,000, the morbidity and mortality rates are high. Arterial embolic etiology composes nearly one-half of AMIs, with a sudden onset of severe abdominal pain considered the most common symptom. Arterial thrombosis is the second most common cause of AMI, which presents similarly to arterial embolic AMI, although often more severe due to anatomic differences. Veno-occlusive causes of AMI are the third most common and are associated with an insidious onset of vague abdominal pain. Each patient is unique, and the treatment plan should be tailored to their individual needs. This may include considering the patient's age, comorbidities, and overall health, as well as their preferences and personal circumstances. A multidisciplinary approach involving specialists from different fields, such as surgeons, interventional radiologists, and intensivists, is recommended for the best possible outcome. Potential challenges in tailoring an optimal treatment plan for AMI may include delayed diagnosis, limited availability of specialized care, or patient factors that make some interventions less feasible. Addressing these challenges requires a proactive and collaborative approach, with regular review and adjustment of the treatment plan as needed to ensure the best possible outcome for each patient.

Identifying temporal variations in burn admissions.

BACKGROUND: Variations in admission patterns have been previously identified in non-elective surgical services, but minimal data on the subject exists with respect to burn admissions. Improved understanding of the temporal pattern of burn admissions could inform resource utilization and clinical staffing. We hypothesize that burn admissions have a predictable temporal distribution with regard to the time of day, day of week, and season of year in which they present. STUDY DESIGN: A retrospective, cohort observational study of a single burn center from 7/1/2016 to 3/31/2021 was performed on all admissions to the burn surgery service. Demographics, burn characteristics, and temporal data of burn admissions were collected. Bivariate absolute and relative frequency data was captured and plotted for all patients who met inclusion criteria. Heat-maps were created to visually represent the relative admission frequency by time of day and day of week. Frequency analysis grouped by total body surface area against time of day and relative encounters against day of year was performed. RESULTS: 2213 burn patient encounters were analyzed, averaging 1.28 burns per day. The nadir of burn admissions was from 07:00 and 08:00, with progressive increase in the rate of admissions over the day. Admissions peaked in the 15:00 hour and then plateaued until midnight (p<0.001). There was no association between day of week in the burn admission distribution (p>0.05), though weekend admissions skewed slightly later (p = 0.025). No annual, cyclical trend in burn admissions was identified, suggesting that there is no predictable seasonality to burn admissions, though individual holidays were not assessed. CONCLUSION: Temporal variations in burn admissions exist, including a peak admission window late in the day. Furthermore, we did not find a predictable annual pattern to use in guiding staffing and resource allocation. This differs from findings in trauma, which identified admission peaks on the weekends and an annual cycle that peaks in spring and summer.

A Novel Sutureless Anastomotic Device in a Swine Model: A Proof of Concept Study.

INTRODUCTION: Vascular reconstruction requires technical expertise and is often time consuming. As a novel alternative to traditional hand-sewn vascular anastomoses, the VasoLock (VL), is a nonabsorbable, sutureless anastomosis device with traction anchors designed to hold free artery ends together. These anchors do not penetrate the vessel wall but adhere by leveraging the elasticity of the vessels to fasten blood vessels together. This pilot study assesses the performance and patency of this novel device in a porcine model of femoral artery injury. METHODS: Female swine (n = 7) underwent femoral artery exposure for a total of 10 VL implanted. Study animals underwent hemodilution to a target hematocrit of 15% and ROTEM was used to assess coagulopathy, followed by an arterial injury via transection. The VL was inserted without any sutures. Flow-probe monitors were positioned proximal and distal to the device and flow rates were measured continuously for a total of 90 min. Flow was analyzed and presented as a ratio of distal to proximal flow with the slope of this ratio across time subsequently determined. Angiographic assessment was completed to evaluate for patency and technical complications after 90 min of implant. RESULTS: The average animal weight was 44.1 ± 3.2 kg. The average mean arterial pressure at the time of implant was 51.2 ± 7.8 mmHg, median heart rate was 77.4 (IQR = 77.25-157.4) beats per minute, and average temperature was 36.1 ± 1.5°C. The baseline hematocrit was 13.5 ± 3.0%, average pH was 7.20 ± 0.1, average clotting time was 154.1 ± 58.7 s and average clot formation time was 103.4 ± 10.9 s all demonstrating the acidotic, hypothermic, and coagulopathic state of the swine at the time of insertion. During the 90-min observation period, the average flow gradient identified across the VL was 0.99 ± 0.24, indicating no significant change in flow across the VL. The average slope of the gradients was 0.0005 (P = 0.22), suggesting the ratio of proximal and distal flow did not change over the 90 min. Following 90 min of dwell time, all VL were patent without technical complication. Angiographic assessment at 90 min demonstrated no evidence of dissection, device migration, arterial extravasation, or thromboembolism with any of the 10 devices. CONCLUSIONS: This pilot study demonstrated technical feasibility of the novel VL device over a 90-min observation period. All VL were patent and no negative events or complications were identified. This technology demonstrated significant promise in a coagulopathic state: additional investigation, involving long-term survival, is warranted for further validation.

Implementation of a patient-centered remote wound monitoring system for management of diabetic foot ulcers.

Background: Regular clinical assessment is critical to optimize lower extremity wound healing. However, family and work obligations, socioeconomic, transportation, and time barriers often limit patient follow-up. We assessed the feasibility of a novel, patient-centered, remote wound management system (Healthy.io Minuteful for Wound Digital Management System) for the surveillance of lower extremity wounds. Methods: We enrolled 25 patients from our outpatient multidisciplinary limb preservation clinic with a diabetic foot ulcer, who had undergone revascularization and podiatric interventions prior to enrollment. Patients and their caregivers were instructed on how to use the digital management system and asked to perform one at-home wound scan per week for a total of 8 weeks using a smartphone application. We collected prospective data on patient engagement, smartphone app useability, and patient satisfaction. Results: Twenty-five patients (mean age 65.5 ± 13.7 years, 60.0% male, 52.0% Black) were enrolled over 3 months. Mean baseline wound area was 18.0 ± 15.2 cm2, 24.0% of patients were recovering from osteomyelitis, and post-surgical WiFi stage was 1 in 24.0%, 2 in 40.0%, 3 in 28.0%, and 4 in 8.00% of patients. We provided a smartphone to 28.0% of patients who did not have access to one that was compatible with the technology. Wound scans were obtained by patients (40.0%) and caregivers (60.0%). Overall, 179 wound scans were submitted through the app. The mean number of wound scans acquired per patient was 0.72 ± 0.63 per week, for a total mean of 5.80 ± 5.30 scans over the course of 8 weeks. Use of the digital wound management system triggered an early change in wound management for 36.0% of patients. Patient satisfaction was high; 94.0% of patients reported the system was useful. Conclusion: The Healthy.io Minuteful for Wound Digital Management System is a feasible means of remote wound monitoring for use by patients and/or their caregivers.

Association of Year of Surgery and Carotid Stenting Outcomes in High-risk Patients, 2015-2021.

This cohort study quantifies the yearly trends and outcomes of transcarotid artery revascularization vs transfemoral carotid artery stenting among high-risk patients from 2015 to 2021.

A 10-Year Analysis of Representation of Women in Patent Applications and NIH Funding in Vascular Surgery.

BACKGROUND: There has been an increasing focus on gender disparities in the medical field and in the field of vascular surgery specifically. We aimed to characterize gender representation in vascular surgery innovation over the past 10 years, using metrics of patents and National Institutes of Health (NIH) support. METHODS: We performed a retrospective review of all vascular-related patent filings (Google Scholar) and NIH-funded grants (NIH RePORTER) over a 10-year period (January 1st, 2012, to December 31st, 2021). Gender-API (Application Programming Interface) was used to identify the gender of the inventors, with manual confirmation of a 10% random sample. Gender representation for patent inventors and grant principal investigators (PIs) were compared using Chi-squared and Student's t-tests as appropriate. Yearly temporal changes in representation were analyzed using Wilcoxon signed-rank tests and linear regression analyses. RESULTS: We identified 2,992 unique vascular device patents with 6,093 associated inventors over 10 years. Women were underrepresented in patent authorship overall (11.5%), and were least likely to be listed as first inventor (8.9%) and most commonly fourth and fifth inventors (15.5% and 14.1%, respectively) compared to men. There was no significant change in representation of women inventors over time (-0.2% females per year, 95% confidence interval (CI) -0.54 to 0.10). We identified 1736 total unique NIH grants, with 23.8% of funded projects having women PIs. There was an increase in the proportion of women PIs over time (+1.31% per year, 95% CI 0.784 to 1.855; P < 0.001). Projects with women PIs received mean total awards that were significantly lower than projects with men PIs ($350,485 ± $220,072 vs. $451,493 ± $411,040; P < 0.001), but the overall ratio of funding:women investigators improved over time (+$11,531 per year, 95% CI $6,167 to $16,895; P = 0.0011). CONCLUSIONS: While we have made strides in increasing the number of women in the surgical research space, there is still room for improvement in funding parity. In addition, we found substantial and persistent room for improvement in representation of women in surgical innovation. As we enter a new frontier of surgery hallmarked by equalizing gender representation, these data should serve as a call-to-action for initiative aimed at rebuilding the foundation of surgical innovations upon equal gender representation.

Thoracic Endovascular Aortic RepairAcutely Augments Left Ventricular Biomechanics in An Animal Model: A Mechanism for Postoperative Heart Failure and Hypertension.

BACKGROUND: Thoracic aortic stent grafts are thought to decrease aortic compliance and may contribute to hypertension and heart failure after thoracic endovascular aortic repair (TEVAR). Left ventricular (LV) biomechanics immediately after TEVAR, however, have not been quantified. Pressure-volume (PV) loop analysis provides gold-standard LV functional information. The aim of this study is to use an LV PV loop catheter and analysis to characterize the LV biomechanics before and acutely after TEVAR. METHODS: Anesthetized Yorkshire swine (N = 6) were percutaneously instrumented with an LV PV loop catheter. A 20 mm × 10 cm stent graft was deployed distal to the left subclavian via the femoral artery under fluoroscopy. Cardiac biomechanics were assessed before and after TEVAR. As a sensitivity analysis, inferior vena cava occlusion with PV loop assessment was performed pre and post-TEVAR in 1 animal to obtain preload and afterload-independent end-systolic and end-diastolic PV relationships (ESPVR and EDPVR). RESULTS: All animals underwent successful instrumentation and TEVAR. Post-TEVAR, all 6 animals had higher mean LV ESP (106 vs. 118 mm Hg, P = 0.04), with no change in the EDPVR. inferior vena cava occlusion also moved the ESPVR curve upward and leftward, indicating increased LV work per unit time. There was no augmentation of EDPVR following TEVAR (P > 0.05). Postmortem exams in all animals revealed appropriate stent placement and no technical complications. CONCLUSIONS: TEVAR was associated with an acute increase in LV end-systolic pressure and shift in the ESPVR, indicating increased ventricular work. This data provides potential mechanistic insights into the development of post-TEVAR hypertension and heart failure. Future stent graft innovation should focus on minimizing the changes in cardiac physiology.

How to TEVAR swine for scientific research: Technical, anatomic, and device considerations to translate human TEVAR techniques into the large animal laboratory.

OBJECTIVE: Thoracic Endovascular Aortic Repair (TEVAR) is well established in humans. Despite widespread use, additional research questions related to thoracic aortic stenting and endovascular innovation require large animal models. Translating human TEVAR devices and techniques into animal models, however, is a challenge even for experienced endovascular surgeons looking to develop a large animal TEVAR model.This article describes swine-specific strategies to deploy human TEVAR stent grafts, delineate how to select, size, prepare, and re-use human stents and deployment systems in swine, and how to translate human imaging modalities to large animal TEVAR. METHODS: We describe a selection of related TEVAR models and techniques in Yorkshire swine to support scientific inquiry. This includes an animal husbandry and pre-operative preparation and planning program. All imaged specimens in this paper are castrated male Yorkshire swine in the 60-80 kg range and underwent TEVAR with the Medtronic Navion stent and deployment system. RESULTS: To study human aortic stent grafts in swine, the animals generally must be at least 50 kgs to guarantee a 2 cm internal aortic diameter at the left subclavian, and for the iliac arteries to accommodate the human deployment system. Swine will have longer torsos and shorter iliofemoral segments than a human of the same weight which can make human deployment systems too short to reach the left subclavian from the femoral arteries in larger animals. We provide techniques to overcome this, including open iliac access or upside-down carotid TEVAR, which may be particularly useful if the scientific data would be confounded by iliofemoral access.Unlike humans that present clinically with axial imaging, swine will generally not have preoperative imaging, and many translational research laboratories do not have access to inexpensive preoperative CT, or any intraoperative CT scanning, which we are fortunate to have. We describe, therefore, several strategies for imaging in this setting including TEVAR via C-arm fluoroscopy and with or without in-laboratory CT scanning. Due to the low-resource setting of most large animal laboratories, as compared to a human hybrid room, we also describe several techniques to reduce cost and reuse materials, including the stent grafts, which at the end of non-survival experiments can be recovered during necropsy, cleaned, reinserted into the deployment device and reused on additional animals. CONCLUSIONS: This article describes a collection of related techniques and tips to translate human TEVAR imaging, sizing/selection, deployment, and anatomy to swine research. Using this framework alone, an experienced human vascular or endovascular surgeon may develop a complete aortic stenting animal model with strategies for scientific data acquisition.

Exploring Intra-arterial Contrast Administration for Intraoperative Imaging Using a Swine Model.

Intraoperative computed tomography (CT) imaging with endovascular delivery of intra-arterial (IA) contrast could potentially provide higher attenuation with lower contrast volumes than intravenous (IV) administration. We aimed to compare IA and IV contrast use for organ-specific CT abdominal imaging. Five anesthetized swine had external jugular and brachial artery access with ascending aortic pigtail placement. An IV protocol was 100 mL at 5 mL/sec over 20 sec vs 50 mL of IA contrast at 5 mL/sec over 10 sec. Region-of-interest markers were applied to anatomical regions to measure attenuation (HU) over time. IA and IV contrast protocols achieved adequate aortic opacification (IA, 455 ± 289 vs IV, 450 ± 114 HU). The IA contrast aortic attenuation curve reached peak attenuation compared with IV contrast (IA, 8 vs 23 sec; P < .001). Time to peak attenuation was similar between IA and IV contrast in the portal vein (IA, 38 vs IV, 42 sec, P = .25). IA administration achieved a superior contrast-to-noise ratio (CNR) in less time compared with IV (R2 = .94; P < .001). IA contrast achieved adequate opacification with less bolus broadening and a superior CNR compared with IV contrast while using a smaller contrast volume for directed organ-directed imaging.

Contemporary Management and Outcomes of Injuries to the Inferior Vena Cava: A Prospective Multicenter Trial From PROspective Observational Vascular Injury Treatment.

INTRODUCTION: Injuries to the inferior vena cava (IVC), while uncommon, have a high mortality despite modern advances. The goal of this study is to describe the diagnosis and management in the largest available prospective data set of vascular injuries across anatomic levels of IVC injury. METHODS: The American Association for the Surgery of Trauma PROspective Observational Vascular Injury Treatment (PROOVIT) registry was queried from November 2013 to January 2019. Demographics, diagnostic modalities, injury patterns, and management strategies were recorded and analyzed. Comparisons between anatomic levels were made using non-parametric Wilcoxon rank-sum statistics. RESULTS: 140 patients from 19 institutions were identified; median age was 30 years old (IQR 23-41), 75% were male, and 62% had penetrating mechanism. The suprarenal IVC group was associated with blunt mechanism (53% vs 32%, P = .02), had lower admission systolic blood pressure, pH, Glasgow Coma Scale (GCS), and higher ISS and thorax and abdomen AIS than the infrarenal injury group. Injuries were managed with open repair (70%) and ligation (30% overall; infrarenal 37% vs suprarenal 13%, P = .01). Endovascular therapy was used in 2% of cases. Overall mortality was 42% (infrarenal 33% vs suprarenal 66%, P<.001). Among survivors, there was no difference in first 24-hour PRBC transfusion requirement, or hospital or ICU length of stay. CONCLUSIONS: Current PROOVIT registry data demonstrate continued use of ligation extending to the suprarenal IVC, limited adoption of endovascular management, and no dramatic increase in overall survival compared to previously published studies. Survival is likely related to IVC injury location and total injury burden.