Postoperative Spinal Cord Ischemia Monitoring: A Review of Techniques Available after Endovascular Aortic Repair.

BACKGROUND: Spinal cord ischemia is one of the complications that can occur after open and endovascular thoracoabdominal aortic repair. This occurs despite various perioperative approaches, including distal aortic perfusion, hybrid procedures with extra anatomical bypasses, motor-evoked potential, and cerebrospinal fluid drainage. The inability to recognize spinal ischemia in a timely manner remains a devastating complication after thoracoabdominal aortic repair.This review aims to look at novel technologies that are designed for continuous monitoring to detect early changes that signal the development of spinal cord ischemia and to discuss their benefits and limitations. METHODS: We conducted a systematic review of the technologies available for continuous monitoring in the intensive care unit for early detection of spinal cord ischemia. Studies were eligible for inclusion if they used different technologies for monitoring spinal ischemia during the postoperative period. All articles that were not available in English were excluded. To ensure that all relevant articles were included, no other significant restrictions were imposed. RESULTS: We identified 59 studies from the outset to December 2022 to be included in our study. New techniques have been studied as potentially useful monitoring tools that could provide simple and effective monitoring of the spinal cord. These include near-infrared spectroscopy, contrast-enhanced ultrasound, magnetic resonance imaging, fiber optic monitoring of the spinal cord, and cerebrospinal fluid biomarkers. CONCLUSIONS: Despite the development of new techniques to monitor for postoperative spinal cord ischemia, their use remains limited. We recommend more future research to ensure rapid intervention for our patients.

Diagnostic Accuracy of FDG PET for the Identification of Vascular Graft Infection.

BACKGROUND: Fluorodeoxyglucose (FDG) positron emission tomography (FDG PET/CT) can be used to identify and localize infection in patients with vascular graft infections (VGI). We aimed to evaluate the diagnostic accuracy of 18F-FDG PET/CT by defining thresholds for standardized uptake value (SUV) and tissue-to-background ratio (TBR) that would accurately identify the presence of vascular graft infection. METHODS: Patients with suspected VGI were prospectively recruited and underwent 18F-FDG PET/CT scans. Diagnosis was based on clinical, laboratory and radiologic findings, and blinded to the results of the PET/CT scan. Receiver operator characteristics (ROC) curve analysis was done to determine optimal thresholds for SUV and TBR. RESULTS: Our final cohort consisted of 28 patients with suspected VGI (mean ± SD age 67 ± 10 years, 61% men), of which 15 patients (54%) had definitive VGI. The cohort included 61% prosthetics grafts and 39% stent-grafts. The type of graft included in this study were biologic (4%), Dacron (64%) and Polytetrafluoroethylene (32%). The location of the implanted grafts was aortic (54%) and peripheral arterial reconstruction (46%). The location of the peripheral graft was 77% in lower extremity and 23% in the upper extremity (arterio-venous grafts for dialysis access). Using ROC analysis, SUV max of 4.5, SUV mean of 3.7, and a TBR of 1.6 gave the best balance between sensitivity and specificity (93%/92%, 100%/92% and 93%/92%, respectively). All thresholds had an area under the curve ≥0.93 and correct reclassification rate ≥93%. CONCLUSIONS: Our data suggests that FDG PET/CT can be used to reliably and accurately diagnose VGI. The dual anatomic-physiologic information from FDG PET/CT can complement clinical diagnosis particularly in uncertain cases.

Vasculink iPhone Application and Risk Prediction Model for Groin Complication in Vascular Surgery.

BACKGROUND: Postoperative groin complication is a common cause of morbidity in vascular surgery. Prophylactic wound adjuncts addressing this issue have been shown to reduce complications in high-risk patients, but their widespread implementation is limited by their high cost. This study introduces a risk prediction model for patients at a high risk for groin complication which can be accessed through the iPhone application, Vasculink. METHODS: A literature search identified risk prediction models for groin complication in vascular surgery. Odds ratios of risk factors that were present in at least 2 published models were calculated with a pooled effect size. The weighted risk for each factor was used to create our model and a cutoff point defining high risk patients was chosen. The initial model was assessed and validated using a split-sample methodology on a cohort identified via a retrospective chart review of all patients undergoing open vascular surgery at our institution between 2017 and 2020. Model performance was assessed using the C-statistic. RESULTS: Risk factors included in our model were female gender, body mass index ≥28 kg/m2, ever-smoker, reoperation, use of prosthetic, emergency, and end-stage renal disease. Of 216 patients, 131 were at a high risk. The overall groin complication rate was 43%, and specific complication rates were 27% infection, 14.8% seroma, and 6.9% hematoma. Our model's sensitivity and specificity were 92.47% and 60.98%, respectively. The C-statistic is 0.768. CONCLUSIONS: By using risk factors identified in the literature we have been able to establish a highly sensitive risk prediction model for groin complication following open vascular surgery. By incorporating our model into an iPhone application, Vasculink, we hope to facilitate preoperative decision making regarding the use of prophylactic wound adjuncts.

Contemporary Review to Reduce Groin Surgical Site Infections in Vascular Surgery.

Surgical site infection (SSIs) in lower extremity vascular procedures is a major contributor to patient morbidity and mortality. Despite previous advancements in preoperative and postoperative care, the surgical infection rate in vascular surgery remains high, particularly when groin incisions are involved. However, successfully targeting modifiable risk factors reduces the surgical site infection incidence in vascular surgery patients. We conducted an extensive literature review to evaluate the efficacy of various preventive strategies for groin surgical site infections. We discuss the role of preoperative showers, preoperative and postoperative antibiotics, collagen gentamicin implants, iodine impregnated drapes, types of skin incisions, negative pressure wound therapy, and prophylactic muscle flap transposition in preventing surgical site infection in the groin after vascular surgical procedures.

Nanotechnology applications for cardiovascular disease treatment: Current and future perspectives.

A large majority of cardiovascular nanomedicine research has focused on fabricating designer nanoparticles for improved targeting as a means to overcome biological barriers. For cardiac related disorders, such as atherosclerosis, hypertension, and myocardial infarction, designer micro or nanoparticles are often administered into the vasculature or targeted vessel with the hope to circumvent problems associated with conventional drug delivery, including negative systemic side effects. Additionally, novel nano-drug carriers that enter circulation can be selectively uptaken by immune cells with the intended purpose that they modulate inflammatory processes and migrate locally to plaque for therapeutic payload delivery. Indeed, innovative design in nanoparticle composition, formulation, and functionalization has advanced the field as a means to achieve therapeutic efficacy for a variety of cardiac disease indications. This perspective aims to discuss these advances and provide new interpretations of how nanotechnology can be best applied to aid in cardiovascular disease treatment. In an effort to spark discussions on where the field of research should go, we share our outlook in new areas of nanotechnological inclusion and integration, such as in vascular, implantable, or wearable device technologies as well as nanocomposites and nanocoatings. Further, as cardiovascular diseases (CVD) increasingly claim a number of lives globally, we propose more attention should be placed by researchers on nanotechnological approaches for risk factor treatment to aid in early prevention and treatment of CVD.

Mimicking cardiac tissue complexity through physical cues: A review on cardiac tissue engineering approaches.

Cardiovascular diseases are the number one killer in the world.1,2 Currently, there are no clinical treatments to regenerate damaged cardiac tissue, leaving patients to develop further life-threatening cardiac complications. Cardiac tissue has multiple functional demands including vascularization, contraction, and conduction that require many synergic components to properly work. Most of these functions are a direct result of the cardiac tissue structure and composition, and, for this reason, tissue engineering strongly proposed to develop substitute engineered heart tissues (EHTs). EHTs usually have combined pluripotent stem cells and supporting scaffolds with the final aim to repair or replace the damaged native tissue. However, as simple as this idea is, indeed, it resulted, after many attempts in the field, to be very challenging. Without design complexity, EHTs remain unable to mature fully and integrate into surrounding heart tissue resulting in minimal in vivo effects.3 Lately, there has been a growing body of evidence that a complex, multifunctional approach through implementing scaffold designs, cellularization, and molecular release appears to be essential in the development of a functional cardiac EHTs.4-6 This review covers the advancements in EHTs developments focusing on how to integrate contraction, conduction, and vascularization mimics and how combinations have resulted in improved designs thus warranting further investigation to develop a clinically applicable treatment.

Nano encapsulated novel compound SA-10 with therapeutic activity in both acute and chronic murine hindlimb ischemia models.

The production dysregulation of reactive oxygen species (ROS) and nitric oxide (NO) in ischemic tissues results in endothelial dysfunction, hyperinflammation and poor blood circulation. Here, we report a hybrid molecule, SA-10 with both NO donating and ROS scavenging abilities that demonstrated potent cytoprotection and tube formation activity in endothelial cells under H2O2-induced oxidative stress. SA-10 loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (SA-10 NPs) were delivered intramuscularly (IM) to two murine hindlimb ischemia models. In the acute mode ischemia/reperfusion (I/R), the muscle damage, hyperinflammation, and lung edema were significantly reduced 3 days post-dose while in the chronic ischemia model, significant improvement of blood perfusion and physical endurance was observed over 30 days (P < 0.05). Elderly patients with acute and chronic limb ischemia have limited options for surgical or endovascular interventions, so we anticipate that a product like SA-10 NPs has potential as one of the therapeutic alternatives to surgery.

Revascularization with Obturator or Hemi-neoaortoiliac System for Partial Aortic Graft Infections.

BACKGROUND: Infections of isolated limbs of prosthetic grafts are challenging. Management can be morbid, involving partial or complete removal of all prosthetic material followed by aortic reconstruction. More limited resections of only infected material and reconstruction of the affected iliac limb has been reported as a viable surgical option. We review 2 academic institution's experiences treating limited aortic graft infections by obturator canal bypass (OCB) or hemi-neoaortoiliac system (H-NAIS). METHODS: A retrospective review of OCB at one institution between 1995 and 2013 and H-NAIS at the other institution between 2003 and 2014 was conducted. Demographics, comorbidities, and postoperative and medium-term events were recorded. Outcomes were patency, limb salvage, graft preservation without reinfection, and survival. RESULTS: OCB was performed in 18 limbs and H-NAIS in 34 limbs. The OCB group had a higher prevalence of cancer (40% vs. 10%; P = 0.04). The most common treatment indication was infection of an aortobifemoral bypass limb in both groups. No differences were seen in overall graft infection, with one patient suffering a late graft reinfection (6% of OCB versus 0% in H-NAIS; P = 0.35). There were no perioperative deaths in either group. Regarding major adverse limb events, there were no amputations performed in the perioperative period in either group. The most frequent organism cultured in both OCB and H-NAIS was Staphylococcus aureus. Surgery duration was similar between the groups (OCB 379 ± 115 minutes vs. H-NAIS 370 ± 137 minutes; P = 0.8) as was the length of stay (OCB 10.5 ± 5.3 days vs. H-NAIS 12.4 ± 10.6 days; P = 0.4). At 36 months, there was no difference in primary patency (OCB 45% vs. H-NAIS 63%; P = 0.7), primary-assisted patency (OCB 51% vs. H-NAIS 61%; P = 0.5), or secondary patency (OCB 68% vs. H-NAIS 63%; P = 0.6) between the groups. Endovascular and open reinterventions occurred more frequently in OCB than in H-NAIS (61.1% vs. 23.5%; P = 0.007). There were no differences in overall survival (OCB 83% vs. H-NAIS 81%; P = 0.6), and no significant difference in amputation rate was seen during the follow-up period (OCB 17% vs. H-NAIS 6%; P = 0.35). CONCLUSIONS: OCB and H-NAIS are effective strategies for treatment of limited aortic graft infections with reasonable patency, survival, and limb salvage at medium-term follow-up. Prudent patient selection and institutional experience with aortic graft infection treatment leads to good outcomes with lifelong follow-up recommended. Further study of the optimal treatment strategy for this complex group of patients is needed.

Contemporary outcomes for ruptured abdominal aortic aneurysms using endovascular balloon control for hypotension.

OBJECTIVE: Ruptured abdominal aortic aneurysm (rAAA) continues to portend significant mortality, despite ruptured endovascular aneurysm repair (rEVAR), enhanced perioperative care, and endovascular balloon control (EBC) for hypotension. We review our academic institution's experience using a protocol of EBC for all hypotensive patients, irrespective of type of repair. METHODS: A retrospective review was conducted of 66 cases of rAAA treated at a single academic institution from 2007 to 2016 using EBC for hypotensive patients. Demographics, comorbidities, intraoperative parameters, and clinical outcomes were recorded. Patients were studied with respect to hemodynamic status, rEVAR, or ruptured open aortic repair in the setting of EBC for hypotension. RESULTS: rEVAR was performed in 43 patients (65%) and ruptured open aortic repair in 23 patients (35%). rAAA was treated in 51 men (77%). Mean rAAA size was 7.6 mm, and mean age of the patients was 73 years. Perioperative survival was 82%. Overall survival at 30 days, 1 year, and 5 years was 71%, 65%, and 52%. Blood transfusion and severe hypotension were significant predictors of mortality at 30 days on multivariable analysis (odds ratio of 1.2 [P = .08] and 39 [P = .03], respectively). Severe hypotension was defined as a mean arterial blood pressure <65 mm Hg and vasopressor use and was present in 59% of the cohort. Normotension was defined as an absence of these conditions and was present in 12%, with 29% of patients exhibiting moderate hypotension. There was no difference in 30-day survival between normotensive and moderately hypotensive patients. The 30-day survival for severely hypotensive patients was 61% vs 85% for moderately hypotensive patients (P = .003), with a significant difference between groups that persisted at 1 year (85% vs 51%; P = .008) and 5 years (66% vs 51%; P = .017). CONCLUSIONS: Good midterm outcomes for moderately hypotensive and normotensive patients can be obtained using an EBC protocol for hypotension with a regionalized transport system directly to the operating room. Severely hemodynamically unstable rAAA patients still pose a significant challenge despite mitigation of hypotension by EBC, suggesting that survival may be compromised by factors other than hypotension alone. We still advocate for the use of EBC for all hypotensive patients as part of a defined rAAA protocol before definitive repair.

Clinical outcomes of obturator canal bypass.

OBJECTIVE: Infected aortofemoral grafts pose a formidable challenge with a significant risk of limb loss and high mortality. Despite successful reports of obturator canal bypass (OCB) for infected aortofemoral graft and complicated groins, the technique has not gained widespread use. We reviewed our experience with OCB and performed a systematic review of the literature. METHODS: A retrospective review of patients who underwent OCB in our institution between 1995 and 2013 was conducted. Demographics of the patients, comorbidities, previous interventions, and postoperative and longer term related events were recorded. Outcomes were primary and secondary patency, limb salvage, and survival rates. For the literature review, all published series in the English language were identified through a PubMed database query. RESULTS: Fifteen patients underwent 18 OCBs during the study period. Mean age was 59.6 ± 12 years, and 11 were men. Indications for surgery were chronic infection in 10 patients and acute bleeding in 5. Polytetrafluoroethylene was used in all cases. Mean clinical follow-up was 57.7 ± 42.3 months (range, 7.4-181). The 30-day complications included three (16.7%) superficial wound infections without any cardiac events, stroke, or death. Midterm outcomes included five late deaths and one myocardial infarction. Regarding major adverse limb events, three patients underwent above-knee amputation. Another procedure was required in 11 of the 18 limbs (61%) at a mean duration of 42 months for reoperation and 35 months for reintervention. One OCB (6%) became infected, requiring removal at 42 months. Primary, primary assisted, and secondary patency was 65%, 71%, and 88% at 24 months, respectively. Overall survival and limb salvage was 83% and 81% at 36 months, respectively. CONCLUSIONS: The OCB can be performed safely with minimal early morbidity and mortality in well-selected patients with infections limited to one femoral anastomosis site. Limb salvage and overall mortality in this series are excellent and in agreement with the reported literature on OCB. Long-term follow-up is recommended because of a significant reoperation and reintervention rate.

Successful Management of Arterial Pseudoaneurysm Caused by Stent Fracture.

Pseudoaneurysm is a relatively common complication of arterial injury. Arterial pseudoaneurysms have many different etiologies, including trauma, iatrogenic injury, vascular repair, infection, and vasculitides. In this case report, we present a pseudoaneurysm created by a fracture of superficial femoral artery (SFA) stent secondary to a mechanical fall. To our knowledge, this is the first report of a symptomatic pseudoaneurysm caused by a SFA stent fracture. The large, unruptured pseudoaneurysm in this case was successfully treated with a covered stent and pseudoaneurysm exclusion.

Inferior Vena Cava Filters: An Overview.

For patients with existing venous thromboembolisms (VTEs), anticoagulation remains the standard of care recommended across multiple professional organizations. However, for patients who developed a deep venous thrombosis (DVT) and/or a pulmonary embolism and cannot tolerate anticoagulation, inferior vena cava (IVC) filters must be considered among other alternative treatments. Although placement of a filter is considered a low-risk intervention, there are important factors and techniques that surgeons and interventionalists should be aware of and prepared to discuss. This overview covers the basics regarding the history of filters, indications for placement, associated risks, and techniques for difficult removal.

Open repair of a proximal left subclavian artery mycotic aneurysm with median claviculectomy.

Surgical repair of a subclavian artery mycotic aneurysm is dependent on aneurysm-specific characteristics and anatomic exposures could require sternotomy, thoracotomy, or supraclavicular incisions. Alternatively, a median claviculectomy can be used. We successfully performed a subclavian artery to axillary artery bypass with median claviculectomy in a 23-year-old man with multiple comorbidities. Postoperative Doppler ultrasound showed a patent left axillary artery with a palpable left radial artery, and the patient demonstrated full left shoulder range of motion without any significant deformities. This case suggests that a median claviculectomy can produce satisfactory outcomes in patients with subclavian artery mycotic aneurysms.

Electrospun Chitosan-Based Nanofibrous Coating for the Local and Sustained Release of Vancomycin.

As the population ages, the number of vascular surgery procedures performed increases. Older adults often have multiple comorbidities, such as diabetes and hypertension, that increase the risk of complications from vascular surgery including vascular graft infection (VGI). VGI is a serious complication with significant morbidity, mortality, and healthcare costs. Here, we aimed to develop a nanofibrous chitosan-based coating for vascular grafts loaded with different concentrations of the vancomycin antibiotic vancomycin (VAN). Blending chitosan with poly(vinyl alcohol) or poly(ethylene oxide) copolymers improved solubility and ease of spinning. Thermal gravimetric analysis and Fourier transform infrared spectroscopy confirmed the presence of VAN in the nanofibrous membranes. Kinetics of VAN release from the nanofibrous mats were evaluated using high-performance liquid chromatography, showing a burst followed by sustained release over 24 h. To achieve longer sustained release, a poly(lactic-co-glycolic acid) coating was applied, resulting in extended release of up to 7 days. Biocompatibility assessment using human umbilical vein endothelial cells demonstrated successful attachment and viability of the nanofiber patches. Our study provides insights into the development of a drug delivery system for vascular grafts aimed at preventing infection during implantation, highlighting the potential of electrospinning as a promising technique in the field of vascular surgery.

Biodesign: Engineering an aortic endograft explantation tool.

Endovascular aortic repair (EVAR) graft failure can be as high as 16% to 30% owing to endoleak, graft migration, or infection, often necessitating explantation, leading to potential morbidity (31%) and mortality (6.3%). Graft prongs frequently tear through the endothelium during explantation, leading to endothelial damage and subsequent fatal bleeding. The current standard of care involves different suboptimal techniques such as the syringe technique in which a cylinder is improvised by cutting a syringe in half and pushed over the graft hooks in a rotating motion, until covered for manual explantation. Because there is no commercially available product to address this shortcoming in graft explantation, we engage in the biodesign process to produce a functional explantation device. We designed and prototyped multiple potential solutions to remove EVAR endografts safely. Silicone tubing with EVAR endografts deployed in the lumen were used to simulate a grafted aorta and test each prototype. Prototypes were compared in their ability to meet design criteria including decrease in graft diameter, prevention of arterial dissection, ease of use, and decrease in procedure time. After determining the single best prototype, surgeon feedback was elicited to iteratively improve the original design. The most effective design uses a tapered lumenal geometry that decreases the EVAR graft diameter and uses stainless steel beads to prevent shear stress to the simulated aorta. A distal grip allows for easy single hand manipulation of the device, while a latching mechanism allows for smooth placement and removal over the endograft. After rigorous prototyping, our device proved feasible and effective for safe EVAR explantation, allowing this procedure to be performed safely.

Telomerase mRNA Enhances Human Skin Engraftment for Wound Healing.

Deep skin wounds represent a serious condition and frequently require split-thickness skin grafts (STSG) to heal. The application of autologous human-skin-cell-suspension (hSCS) requires less donor skin than STSG without compromising the healing capacity. Impaired function and replicative ability of senescent cutaneous cells in the aging skin affects healing with autologous hSCS. Major determinants of senescence are telomere erosion and DNA damage. Human telomerase reverse transcriptase (hTERT) adds telomeric repeats to the DNA and can protect against DNA damage. Herein, hTERT mRNA lipid nanoparticles (LNP) are proposed and evaluated for enhancing cellular engraftment and proliferation of hSCS. Transfection with optimized hTERT mRNA LNP system enables delivery and expression of mRNA in vitro in keratinocytes, fibroblasts, and in hSCS prepared from donors' skin. Telomerase activity in hSCS is significantly increased. hTERT mRNA LNP enhance the generation of a partial-thickness human skin equivalent in the mouse model, increasing hSCS engraftment (Lamin) and proliferation (Ki67), while reducing cellular senescence (p21) and DNA damage (53BP1).

Houston Methodist Ruptured Abdominal Aortic Aneurysm Guidelines.

Ruptured abdominal aortic aneurysm (RAAA) is an acute aortic condition that requires emergent intervention and appropriate continuity of care to optimize patient outcomes. We describe the standardized RAAA protocol at the Houston Methodist Hospital Acute Aortic Treatment Center, developed to navigate critical patient transfer periods safely and efficiently, make crucial decisions about surgical intervention, and clearly communicate these plans with other care team providers. Our workflow is organized into five phases: prehospital, preoperative, intraoperative, postoperative, and post-discharge. We identify the transfer center, anesthesia, operating room nursing staff, surgeons, and intensive care unit as key entities of our acute aortic pathology care team. This systematic protocol for the management of acute aortic emergencies such as RAAA identifies critical decision points, potential complications at each stage, and recommendations for best practice.

Cadaveric aortic aneurysm creation: A life-like model for training endovascular repair.

The recent decline in RAAA incidence and the fast paced scenario with associated challenges regarding training calls for initiative for a better training environment to maximize learning. This led us to the creation of a pulsatile human cadaveric RAAA model. Fresh frozen cadaver was used to create RAAA with BioTissue in hybrid suite with ability to perform CBCTA for sizing. As a proof of concept, the model was used to perform REVAR with proximal CODA balloon control. The model proved to be feasible and we believe it is a better environment to train and gain adequate proficiency in RAAA management.

Targeted biodegradable nanoparticles for drug delivery to smooth muscle cells.

Targeted delivery of therapeutic agents to prevent smooth muscle cell (SMC) proliferation is important in averting restenosis (a narrowing of blood vessels). Since platelet derived growth factor (PDGF) receptors are over-expressed in proliferating SMCs after injury from cardiovascular interventions, such as angioplasty and stent implantation, our hypothesis is that conjugation of PDGF-BB (platelet-derived growth factor BB (homodimer)) peptides to biodegradable poly (D,L-lactic-co-glycolide) (PLGA) nanoparticles (NPs) would exhibit an increased uptake of these NPs by proliferating SMCs. In this study, poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles containing dexamethasone were formulated and conjugated with PDGF-BB peptides. These NPs were stable, biocompatible, and exhibited a sustained drug release over 14 days. Various particle uptake studies using HASMCs (human aortic smooth muscle cells) demonstrated that PDGF-BB peptide-conjugated nanoparticles significantly increased cellular uptake and decreased proliferation of HASMCs compared to control nanoparticles (without conjugation of PDGF-BB peptides). These NPs were internalized primarily by clathrin-mediated endocytosis and macropinocytosis. Our in vitro results suggest that PDGF-BB peptide-conjugated NPs could represent as an effective targeted, sustained therapeutic delivery system to reduce restenosis and neointimal hyperplasia.

Managing an infected femoral artery pseudoaneurysm after thoraco-bifemoral bypass with an innovative configuration.

An infected femoral artery pseudoaneurysm after aortic reconstruction is a devastating surgical complication associated with the morbidity of limb loss and pelvic ischemia with a reinfection rate of ≤10%. In the present case report, we have described a unique approach for an infected femoral pseudoaneurysm after thoraco-bifemoral bypass using an innovative configuration, in addition to an obturator bypass technique, in a patient with a complex vascular history. This unique approach made use of an existing limb of a thoraco-bifemoral bypass graft to provide inflow to two outflow conduits, the external iliac artery and superficial femoral artery, allowing for preservation of both pelvic and lower extremity perfusion.