Treffalls, Rebecca N.

Introduction Lower Extremity Extracorporeal Distal Revascularization (LEEDR) is a novel, preclinically tested technique designed to provide temporary limb perfusion in cases of acute limb ischemia when immediate revascularization is not feasible. Methods LEEDR employs an extracorporeal pump and circuit to draw arterial blood from a proximal inflow site and deliver it to an outflow artery within the ischemic limb. The system is designed for bedside initiation using percutaneous access. Results ALI from embolism, thrombosis, or trauma rapidly leads to irreversible tissue damage. Delays in revascularization are associated with high rates of limb loss and systemic complications. LEEDR offers a time-sensitive intervention aimed at mitigating these risks and preserving limb viability until definitive treatment is available. Conclusion LEEDR is a promising temporary perfusion strategy for limb salvage in ALI. This manuscript outlines its procedural components, technical considerations, and anticipated role in bridging patients to definitive revascularization.

Objectives Traditionally, acute mesenteric ischemia studies are performed by utilizing an open superior mesenteric artery (SMA) occlusion, which is an invasive technique with potentially devastating effects. A new endovascular technique for SMA occlusion using a catheter-balloon system was designed and compared to the open SMA occlusion to test its efficacy and animal safety. Methods All animals underwent open instrumentation of the superior mesenteric vein (SMV) for blood flow monitoring. The animals were grouped into an open SMA occlusion technique group and an endovascular SMA occlusion group. The open SMA occlusion technique group involved exposure of the SMA via left medial visceral rotation with vascular clamping. In the endovascular group, an endovascular balloon was placed in the SMA and inflated to produce occlusion. Results Complete cessation of flow to the SMV was observed in the endovascular group, compared to the residual SMV flow in the open occlusion group. Following a 30-min post-occlusion period, the MAP in the endovascular group increased, compared to a decline of MAP in the open occlusion group. Conclusions This study indicates the endovascular technique provides a more potent SMA occlusion, with insignificant consequences on the overall health of the animal, in contrast to the open vascular clamping.

Background: Traumatic carotid artery pseudoaneurysms (PSAs) represent a vascular anomaly with potential for serious complications, including stroke. Traditional treatments involve endovascular stenting, which may not be ideally suited to otherwise healthy vessels that have the potential to remodel. Given the limitations of smaller animal models in replicating human vasculature and the need for improved treatment modalities, this study introduces a novel swine model for the creation and evaluation of carotid PSAs. Methods: The PSAs were created from bovine dura and anastomosed in an end-to-side fashion to bilateral carotid arteries. The PSAs were radiologically followed up post-operatively and were harvested at 3 and 10 days for histological analysis. Results: Pseudoaneurysms were successfully created in both animals without intra-operative or immediate post-operative complications. Radiological analysis showed well-perfused PSAs with intra-aneurysmal turbulence, hemodynamically mimicking human carotid artery PSAs. There was no evidence of thrombus or arterial stenosis. Histological examinations revealed thrombus maturation and tight anastomosis of the PSA sac with the native artery. Conclusions: This PSA swine model offers a replicable, cost-effective, and easily implemented tool with the potential to advance carotid PSA management and educational efforts in vascular surgery. Clinical Impact The model presented in this methodology paper allows for a standardized PSA animal model allowing for the standardization of a clinical entity which is frequently heterogenenous in morphology. This can allow for the development of new therapies or provide a ground truth for computer modelling for further in silico study.

Background: Autologous arteriovenous fistulas (AVF) are the preferred choice for hemodialysis access due to their longevity, lower complication rates, and mortality benefit. Their use is limited by vein size and necessary maturation period, excluding up to a third of patients. A novel solution to this problem is pump-assisted vein dilation (PAVD), where the vein is “pre-matured” using a miniatured centrifugal pump that draws blood from a central vein, delivering it into the recipient vein (e.g., cephalic) under pressure. The aim of this study is to report the initial safety studies in sheep and a first-in-human (FIH) pilot study as a prelude to a phase 2 clinical study. Methods: Preclinical Study: Three anesthetized male sheep (50-70 kg) underwent cephalic PAVD using the Amplifi Vein Dilation System for 7 days (mean). These subjects and two control animals (no-PAVD) underwent brachiocephalic AVF creation and observation for 6 weeks, with weekly surveillance fistulagrams and duplex ultrasound (U/S). AVFs were then explanted for histological analysis. Clinical Study: Ten patients were recruited for a phase 1 study. They underwent cephalic PAVD for 7 days (mean), followed by brachiocephalic AVF creation and surveillance at 2 and 6 wks. Data on vein diameter and flow rates of the AVF were collected, as well as safety data on complications such as bleeding, infection, and embolism. Results: Preclinical Study: PAVD increased mean±SD vein diameter (mm) from 4.5±1.0 to 8.4±1.0 (p=0.005); leading to greater cephalic vein diameter at the time of AVF creation in the PAVD group vs no-PAVD (8.2±1.3 vs. 3.3±0.7; p<0.05). After 6 wks of maturation, mean vein diameter was still greater in the PAVD group compared to no-PAVD (12.8±2.8 vs. 8.4±0.7; p<0.05). Mean flow increased at 41 mL/min/day versus control animals at 5.2 mL/min/day. Clinical Study: All subjects saw an increase in vein diameter with PAVD at baseline vs. at 6 wks (2.3±0.5 vs. 5.2±0.7; p<0.05), as well as mean flows (mL/min) (285±30 vs. 724±149). There were no Amplifi-related or procedure-related serious adverse events. Conclusion: The translation of PAVD for AVF creation from bench-to-bedside provides safety and efficacy data on a novel solution that can increase the availability of autologous AVFs in patients excluded due to size criteria. The Amplifi vein dilation system can effectively and rapidly dilate peripheral veins without stimulating neointimal hyperplasia. PAVD should be explored in a phase 2 clinical study.

Background: Acute limb ischemia (ALI) requires prompt revascularization to preserve the extremity and minimize the effects of systemic reperfusion. Once ALI is recognized, delays in revascularization are generally due to system issues (e.g., transfer) and there is a need for a method of temporary extremity perfusion to reduce warm ischemic time. Lower Extremity Extracorporeal Distal Revascularization (LEEDR) is a percutaneous technique that uses a pump and circuit to deliver oxygenated blood into a pedal artery. Hypothesis: Extracorporeal perfusion can improve survival from ALI. Aims: The aim of this study is to use a swine model of prolonged hindlimb ischemia to compare survival and functional outcomes of LEEDR versus control (warm ischemia). Methods: Anesthetized female Yorkshire swine (40-60kg) underwent hindlimb ischemia using endovascular balloon occlusion and were randomized to control (n=6) or LEEDR (n=6). Controls underwent 9 hours of ischemia. LEEDR animals underwent contralateral femoral and ipsilateral posterior tibial artery cannulation followed by 8 hours of extracorporeal perfusion into the ischemic limb. Subjects were revascularized by removing the endovascular balloons, restoring extremity blood flow, and undergoing a 4-hour critical care period before extubation and observation for 48 hours. Primary outcome was survival and secondary outcomes included functional extremity scores (Tarlov Gait Score), compartment pressures (mmHg) and biochemical markers of reperfusion. Results: Survival was higher in animals undergoing LEEDR (83% vs. 0%; p=0.001), with most control animals succumbing to acute lung injury. LEEDR animals had a higher functional gait score (5.9±0.3 vs. 2.5±0.7; p<0.001) and lower compartment pressure (8±2 vs. 28±4; p=0.002) compared to controls. Biochemically, the LEEDR group had lower potassium (4.5±0.3 vs. 5.3±0.4; p=0.001) and lactate (1.2±0.5 vs. 2.0±0.7; p<0.001) measurements compared to controls during reperfusion and recovery. Conclusion: LEEDR can effectively mitigate 8 hours of extremity ischemia in a swine model, reducing mortality from reperfusion, while improving functional gait score and eliminating compartment syndrome. This percutaneous approach to ALI opens a new field of extracorporeal limb salvage, which can temporize extremity perfusion improving outcomes in patients who have traditionally had limited options due to prolonged warm ischemia.

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.

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 (R 2 = .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.