Viability of Human Arterial Grafts Monitored by Comet Assay.

An analytical method for studying DNA degradation by electrophoresis after cell lysis and visualization of DNA fragments with fluorescent dye, comet assay, was used to evaluate the viability of the endothelial layer of human arterial grafts with the aim of identifying the procedure that will least damage the tissue before cryopreservation. Four groups of samples were studied: cryopreserved arterial grafts that were thawed in two different ways, slowly lasting 2 hours or rapidly for approx. 7 minutes. Arterial grafts that were collected as part of multiorgan procurement with minimal warm ischemia time. Cadaveric grafts were taken as part of the autopsy, so they have a more extended period of warm ischemia. The HeadDNA (%) parameter and others commonly used parameters like TailDNA (%). TailMoment, TailLength, OliveMoment, TailMoment to characterize the comet were used to assess viability in this study. The ratio of non-decayed to decayed nuclei was determined from the values found. This ratio for cadaveric grafts was 0.63, for slowly thawed cryopreserved grafts 2.9, for rapidly thawed cryopreserved grafts 1.9, and for multi-organ procurement grafts 0.68. The results of the study confirmed the assumption that the allografts obtained from cadaveric donors are the least suitable. On the other hand, grafts obtained from multiorgan donors are better in terms of viability monitored by comet assay. Keywords: Arterial grafts, Cryopreservation, Cadaveric, Multiorgan procurement, Viability, Comet assay.

Long-term outcomes of autologous vein bypass for repair of upper and lower extremity major arterial trauma.

OBJECTIVE: Autologous vein is the preferred bypass conduit for extremity arterial injuries owing to superior patency and low infection risk; however, long-term data on outcomes in civilians are limited. Our goal was to assess short- and long-term outcomes of autologous vein bypass for upper and lower extremity arterial trauma. METHODS: A retrospective review was performed of patients with major extremity arterial injuries (2001-2019) at a level I trauma center. Demographics, injury and intervention details, and outcomes were recorded. Primary outcomes were primary patency at 1 year and 3 years. Secondary outcomes were limb function at 6 months, major amputation, and mortality. Multivariable analysis determined risk factors for functional impairment. RESULTS: There were 107 extremity arterial injuries (31.8% upper and 68.2% lower) treated with autologous vein bypass. Mechanism was penetrating in 77% of cases, of which 79.3% were due to firearms. The most frequently injured vessels were the common and superficial femoral (38%), popliteal (30%), and brachial arteries (29%). For upper extremity trauma, concomitant nerve and orthopedic injuries were found in 15 (44.1%) and 11 (32.4%) cases, respectively. For lower extremities, concomitant nerve injuries were found in 10 (13.7%) cases, and orthopedic injuries in 31 (42.5%). Great saphenous vein was the conduit in 96% of cases. Immediate intraoperative bypass revision occurred in 9.3% of patients, most commonly for graft thrombosis. The in-hospital return to operating room rate was 15.9%, with graft thrombosis (47.1%) and wound infections (23.5%) being the most common reasons. The median follow-up was 3.6 years. Kaplan-Meier analysis showed 92% primary patency at 1 year and 90% at 3 years. At 6 months, 36.1% of patients had functional impairment. Of patients with functional impairment at 6 months, 62.9% had concomitant nerve and 60% concomitant orthopedic injuries. Of those with nerve injury, 91.7% had functional impairment, compared with 17.8% without nerve injury (P < .001). Of patients with orthopedic injuries, 51.2% had functional impairment, vs 25% of those without orthopedic injuries (P = .01). On multivariable analysis, concomitant nerve injury (odds ratio, 127.4; 95% confidence interval, 17-957; P <. 001) and immediate intraoperative revision (odds ratio, 11.03; 95% confidence interval, 1.27-95.55; P = .029) were associated with functional impairment. CONCLUSIONS: Autologous vein bypass for major extremity arterial trauma is durable; however, many patients have long-term limb dysfunction associated with concomitant nerve injury and immediate intraoperative bypass revision. These factors may allow clinicians to identify patients at higher risk for functional impairment, to outline patient expectations and direct rehabilitation efforts toward improving functional outcomes.

Contemporary outcomes for arterial reconstruction with non-saphenous vein cryo-preserved conduits.

OBJECTIVE: Cryopreserved (CP) products are utilized during challenging cases when autogenous or prosthetic conduit use is not feasible. Despite decades of experience with cadaveric greater saphenous vein (GSV), there is limited available data regarding the outcomes and patency of other CP products, specifically arterial and deep venous grafts. This study was designed to evaluate outcomes of non-GSV CP conduits in patients undergoing urgent, emergent, and elective arterial reconstruction at our institution. We hypothesized that non-GSV CP allografts have adequate patency and outcomes and are therefore a feasible alternative to GSV in settings where autologous graft is unavailable or prosthetic grafts are contraindicated. METHODS: This study was approved by the Institutional Review Board at our institution. We retrospectively reviewed charts of patients undergoing arterial reconstructions using CP conduits from 2010 to 2022. Data collected included demographics, comorbidities, smoking status, indications for surgery, indication for CP conduit use, anatomic reconstruction, urgency of procedure, and blood loss. Time-to-event outcomes included primary and secondary graft patency rates, follow-up amputations, and mortality; other complications included follow-up infection/reinfection and 30-day complications, including return to the operating room and perioperative mortality. Time-to-event analyses were evaluated using product-limit survival estimates. RESULTS: Of 96 identified patients receiving CP conduits, 56 patients received non-GSV conduits for 66 arterial reconstructions. The most common type of non-GSV CP product used was femoral artery (31 patients), followed by aorto-iliac artery (22 patients), and femoral vein (19 patients), with some patients receiving more than one reconstruction or CP product. Patients were mostly male (75%), with a mean age of 63.1 years and a mean body mass index of 26.7 kg/m2. Indications for CP conduit use included infection in 53 patients, hostile environment in 36 patients, contaminated field in 30 patients, tissue coverage concerns in 30 patients, inadequate conduit in nine patients, and patient preference in one patient. Notably, multiple patients had more than one indication. Most surgeries (95%) were performed in urgent or emergent settings. Supra-inguinal reconstructions were most common (53%), followed by extra-anatomic bypasses (47%). Thirty-day mortality occurred in 10 patients (19%). Fifteen patients (27%) required return to the operating room for indications related to the vascular reconstructions, with 10 (18%) cases being unplanned and five (9%) cases planned/staged. Overall survival at 6, 12, and 24 months was 80%, 68%, and 59%, respectively. Primary patency at 6, 12, and 24 months was 86%, 70%, and 62%, respectively. Amputation freedom at 6 months, 12 months, and 24 months was 98%, 95%, and 86%, respectively for non-traumatic indications. CONCLUSIONS: Non-GSV CP products may be used in complex arterial reconstructions when autogenous or prosthetic options are not feasible or available.

Modeling human anti-pig xenoimmune responses in a pig artery tissue grafted humanized mouse model.

BACKGROUND: Blood vessels that contain endothelial cells (ECs) on the surface are in direct contact with host blood and are the first target of xenograft rejection. Currently, our understanding of human anti-pig vessel immune responses is primarily based on in vitro assays using pig ECs. Therefore, it is necessary to develop an animal model that permits in vivo study of human immunological rejection of pig vessels. METHODS: Pig artery tissues (PAT) were transplanted into human immune system (HIS) mice or immunodeficient NSG mice (as controls). Intragraft human immune cell infiltration and antibody deposition were quantified using histology and immunohistochemistry. Donor antigen-specific immune responses were quantified using a mixed lymphocyte reaction and a complement-dependent killing assay. RESULTS: Pig CD31+ ECs were detected and increased 2-fold from weeks 3 to 5 in PAT xenografts from immunodeficient NSG mice. However, compared with NSG mice, PAT xenografts in HIS mice had significantly lower numbers of porcine CD31+ ECs and showed a marked reduction from week 3 to week 5. PAT xenograft rejection in HIS mice is associated with intensive infiltration of human immune cells, deposition of human IgM and IgG antibodies, and the formation of a tertiary lymphoid structure. Robust donor pig antigen-specific human T cells and antibody responses were detected in PAT-transplanted HIS mice. CONCLUSION: We have developed a humanized mouse model to evaluate human anti-pig xenoimmune responses by PAT transplantation in vivo. This model is expected to facilitate the refinement of pig gene-editing strategies (the expression on EC surface) and the testing of local immunosuppressive strategies for clinical pig organ xenotransplantation.

Fresh arterial allograft as a replacement for an infected common femoral prosthetic graft and recurrent false aneurysm.

Replacing an infected vascular prosthetic conduit with an allograft is a possible solution of this complication given the low recurrence of infection. It is most commonly utilized for cases where the use of autologous tissue is not an option. We present the case of a 70-year-old patient who had undergone repeated vascular reconstructions in the right lower limb. He was admitted to our department due to a progressively growing mass in the right groin and subsequently placed on the waiting list for a fresh allograft. The patient had the infected false aneurysm and prosthetic material of the femoral bifurcation replaced with an arterial allograft. The previous femoral popliteal autovenous bypass graft was reimplanted into the allograft. There were signs of sepsis during the operation; however, the blood culture was negative. Cultures from neither the wound nor the drain revealed the presence of any bacteria. The patient was discharged on the seventh post-operative day with prophylactic antibiotics. An early followup confirmed that there were no signs of recurrent infection and that the reconstruction remained patent. Seven and half months after the surgery, the femoral popliteal bypass graft became occluded and a conservative approach was chosen. A small thrombosed false aneurysm of the graft was revealed two years after the surgery due to transient non-compliance of the patient to immunosuppression therapy. It was treated conservatively. Two and a half years after the surgery, the allograft still remains open and the limb is preserved.

Mycobacterium Bovis Causing Mycotic Aneurysm Secondary to Intravesical Treatment with Bacillus Calmette-Guérin: A Case Report.

BACKGROUND: Bacillus Calmette-Guerin (BCG) is a live, attenuated strain of Mycobacterium bovis that is used in the treatment of non-muscle invasive bladder cancer (NMIBC). Vascular complications, including mycotic aneurysms, after BCG therapy are exceedingly rare. In this patient population, the diagnosis of mycotic aneurysms can be delayed or missed due to their non-specific clinical and radiologic presentation. Literature review reveals management of mycotic aneurysms attributable to BCG therapy is widely varied.2,5-8,12,15 CASE REPORT: We report a patient who presented with mycotic aneurysm formation secondary to BCG treatment for bladder cancer that was repaired with in-line reconstruction utilizing cryoartery and buttressed with omental flap. We suggest this as an alternative treatment to in-line prosthetic graft or extra-anatomic reconstruction.

REDV-modified decellularized microvascular grafts for arterial and venous reconstruction.

Recently, a decellularized microvascular graft (inner diameter: 0.6 mm) modified with the integrin α4ß1 ligand, REDV, was developed to provide an alternative to autologous-vein grafting in reconstructive microsurgery, showing good early-stage patency under arterial flow in rats. This consecutive study evaluated its potential utility not only as an arterial substitute, but also as a venous substitute, using a rat-tail replantation model. Graft remodeling depending on hemodynamic status was also investigated. ACI rat tail arteries were decellularized via ultra-high-hydrostatic pressure treatment and modified with REDV to induce antithrombogenic interfaces and promote endothelialization after implantation. Grafts were implanted into the tail artery and vein to re-establish blood circulation in amputated Lewis rat tails (n = 12). The primary endpoint was the survival of replants. Secondary endpoints were graft patency, remodeling, and regeneration for 6 months. In all but three cases with technical errors or postoperative self-mutilation, tails survived without any evidence of ischemia or congestion. Six-month Kaplan-Meier patency was 100% for tail-artery implanted grafts and 62% for tail-vein implanted grafts. At 6 months, the neo-tunica media (thickness: 95.0 µm in tail-artery implanted grafts, 9.3 µm in tail-vein implanted grafts) was regenerated inside the neo-intima. In conclusion, the microvascular grafts functioned well both as arterial and venous paths of replanted-rat tails, with different remodeling under arterial and venous conditions.

Cryopreservation moderates the thrombogenicity of arterial allografts during storage.

INTRODUCTION: Management of vascular infections represents a major challenge in vascular surgery. The use of cryopreserved vascular allografts could be a feasible therapeutic option, but the optimal conditions for their production and use are not precisely defined. AIMS: To evaluate the effects of cryopreservation and the duration of storage on the thrombogenicity of femoral artery allografts. METHODS: In our prospective study, eleven multi-organ-donation-harvested human femoral arteries were examined at five time points during storage at -80°C: before cryopreservation as a fresh native sample and immediately, one, twelve and twenty-four weeks after the cryopreservation. Cross-sections of allografts were perfused with heparin-anticoagulated blood at shear-rates relevant to medium-sized arteries. The deposited platelets and fibrin were immunostained. The thrombogenicity of the intima, media and adventitia layers of the artery grafts was assessed quantitatively from the relative area covered by fibrin- and platelet-related fluorescent signal in the confocal micrographs. RESULTS: Regression analysis of the fibrin and platelet coverage in the course of the 24-week storage excluded the possibility for increase in the graft thrombogenicity in the course of time and supported the hypothesis for a descending trend in fibrin generation and platelet deposition on the arterial wall. The fibrin deposition in the cryopreserved samples did not exceed the level detected in any of the three layers of the native graft. However, an early (up to week 12) shift above the native sample level was observed in the platelet adhesion to the media. CONCLUSIONS: The hemostatic potential of cryopreserved arterial allografts was retained, whereas their thrombogenic potential declined during the 6-month storage. The only transient prothrombotic change was observed in the media layer, where the platelet deposition exceeded that of the fresh native grafts in the initial twelve weeks after cryopreservation, suggesting a potential clinical benefit from antiplatelet therapy in this time-window.

Posterior auricular artery free flap reconstruction of the retroauricular sulcus in microtia repair.

BACKGROUND: Autologous repair using costal cartilage grafts remains the most widely accepted method of microtia reconstruction. A major complication of current techniques is loss of ear shape caused by scarring, contracture and cartilage absorption. We present a new surgical technique utilizing the posterior auricular artery free flap in microsurgical reconstruction of the retroauricular sulcus in microtia. METHOD: Reconstruction is performed in two stages. In the first stage, a fabricated costal cartilage framework is inserted into a skin pocket as described by Nagata. In the second stage, the ear framework is elevated from the scalp and held by an additional cartilage wedge. Following indocyanine green angiography perforator mapping, a posterior auricular artery perforator flap is harvested from the contralateral (normal) ear and used to reconstruct the posterior auricular sulcus covering the cartilage framework and elevating wedge. RESULTS: The technique was applied to three patients aged 11-15 years with a follow-up time of 8 months to 3 years. The average flap artery diameter was 0.73 mm and the vein was 0.7 mm. Venous congestion occurred in one case and was resolved with a vein graft leading to complete flap recovery. Good ear shape, elevation, projection, skin color and texture were achieved in all the cases. CONCLUSION: Posterior auricular artery flap reconstruction of the retroauricular sulcus in microtia repair is a useful alternative to the current skin graft and tissue expander-based techniques. It provides the ideal skin color and texture match and may improve the overall results of microtia reconstruction by enhancing vascularity.

Results of cryopreserved arterial allograft replacement for thoracic and thoracoabdominal aortic infections.

BACKGROUND: Primary and secondary thoracic aortic infections are rare but associated with high morbidity and mortality. There is currently no consensus on their optimal treatment. Arterial allografts have been shown to be resistant to bacterial colonization. Complete excision of infected material, especially synthetic grafts, combined with in situ aortic repair is considered the best treatment of abdominal aortic infections. The aim of this study was to assess the management of thoracic and thoracoabdominal aortic infections using arterial allografts. METHODS: Between January 2009 and December 2017, all patients with thoracic and thoracoabdominal aortic native or graft infections underwent complete excision of infected material and in situ arterial allografting. The end points were the early mortality and morbidity rates and early and late rates of reinfection, graft degeneration, and graft-related morbidity. RESULTS: Thirty-five patients with a mean age of 65.6 ± 9.2 years were included. Twenty-one (60%) cases experienced graft infections and 14 (40%) experienced native aortic infections. Eight (22.8%) patients had visceral fistulas: 5 (14.4%) prosthetic-esophageal, 1 (2.8%) prosthetic-bronchial, 1 (2.8%) prosthetic-duodenal, and 1 (2.8%) native aortobronchial. In 12 (34.3%) cases, only the descending thoracic aorta was involved; in 23 (65.7%) cases, the thoracoabdominal aorta was involved. Fifteen (42.8%) patients died during the first month or before discharge: 5 of hemorrhage, 4 of multiorgan failure, 3 of ischemic colitis, 2 of pneumonia, and 1 of anastomotic disruption. Eleven (31.5%) patients required early revision surgery: 6 (17.1%) for nongraft-related hemorrhage, 3 (8.6%) for colectomy, 1 (2.9%) for proximal anastomotic disruption, and 1 (2.9%) for tamponade. One (2.9%) patient who died before discharge experienced paraplegia. One (2.9%) patient experienced stroke. Six (17.1%) patients required postoperative dialysis. Among them, four died before discharge. The mean length of stay in the intensive care unit was 11 ± 10.5 days; the mean length of hospital stay was 32 ± 14 days. During a mean follow-up of 32.3 ± 23.7 months, three allograft-related complications occurred in survivors (15% of late survivors): one proximal and one distal false aneurysm with no evidence of reinfection and one allograft-enteric fistula. The 1-year and 2-year survival rates were 49.3% and 42.5%, respectively. CONCLUSIONS: Although rare, aortic infections are highly challenging. Surgical management includes complete excision of infected tissues or grafts. Allografts offer a promising solution to aortic graft infection because they appear to resist reinfection; however, the grafts must be observed indefinitely because of the risk of late graft complications.

Free neurosensory flap based on the accompanying vessels of lateral sural cutaneous nerve: anatomic study and preliminary clinical applications.

BACKGROUND: The posterior aspect of the leg is an ideal donor site for flap surgery. In this study, the anatomy was investigated of the lateral sural cutaneous nerve (LSCN) and its accompanying artery, superficial lateral sural artery (SLSA), and a lateral sural neurocutaneous flap was designed. METHODS: Five fresh adult cadaver legs perfused with red latex were dissected to observe the course and relationship between LSCN and SLSA. The outer diameter of SLSA at its origin was measured. Then a lateral sural neurocutaneous flap was designed and used to repair soft tissue defects in six patients. RESULTS: The anatomic results showed that the SLSA gave rise to branches that followed the LSCN and ramified into terminals at the ramification of the nerve. It originated directly from the popliteal artery 4.2 ± 0.2 mm above the fibular head, where its outer diameter was 0.96 ± 0.23 mm. Several perforators penetrated from the crural fascia and anastomosed to the SLSA, creating a fine anastomotic network. The clinical results showed that the size of the flap ranged from 12 × 6 cm to 25 × 8 cm. All six flaps survived completely without complications. Follow-up ranged from 6 to 18 months with 11 months on average. The overall contour and sensory recovery of the flap were satisfied. CONCLUSION: A free innervated flap may be elevated safely based on the LSCN and its accompanying vessels. It provides an alternative in reconstruction of soft tissue defects where sensory recovery is important.

Autogenous Arteriovenous Bundle Implantation Maintains Viability Without Increased Immune Response in Large Porcine Bone Allotransplants.

BACKGROUND: Transplantation of living allogeneic bone segments may permit reconstruction of large defects, particularly if viability is maintained without immunosuppression. Development of a new autogenous osseous blood supply accomplishes this goal in rodent experimental models. This study evaluates potential systemic and local inflammatory responses to this angiogenesis in a large-animal model. METHODS: Vascularized allogeneic tibia segments were transplanted orthotopically into matched tibial defects in Yucatan minipigs. Microvascular anastomoses of bone nutrient artery and vein were supplemented by intramedullary placement of an autogenous arteriovenous (AV) bundle in group 1. Group 2 served as a no-angiogenesis control. A 3-drug immunosuppression regimen was withdrawn after 2 weeks. During the 20-week survival period, periodic leukocyte counts and inflammatory cytokine levels were measured. Thereafter, osteocyte survival was quantified and transplant rejection graded by histologic examination and quantitative real-time polymerase chain reaction of immunologic markers. RESULTS: Both groups developed an initial systemic response, which resolved after 4 to 6 weeks. No differences were seen in blood cytokine levels. Interleukin 2 expression was diminished in group 1 tibiae. As expected, nutrient pedicles had thrombosed without sustained immunosuppression, occluded by intimal hyperplasia. In group 1, angiogenesis from the autogenous AV bundle resulted in significantly less osteonecrosis (P = .04) and fibrosis (P = .02) than group 2 allotransplants. CONCLUSIONS: Systemic immune responses to large-bone allotransplants were not increased by generation of an autogenous osseous blood supply within porcine tibial bone allotransplants. Implanted AV bundles diminished inflammation and fibrosis and improved bone viability when compared to no-angiogenesis controls.

The Medial Sural Artery Perforator Flap: Lessons Learned from 200 Consecutive Cases.

BACKGROUND: The medial sural artery perforator flap is a versatile option in reconstructive microsurgery. However, most reports of this flap have been limited by sample size. This study reviews the experience of a single large-volume center using the medial sural artery perforator flap and its variants for a variety of reconstructive purposes. METHODS: A retrospective review of all patients who received the medial sural artery perforator flap reconstruction between March of 2006 and July of 2014 was performed. RESULTS: Two-hundred medial sural artery perforator flaps were used at three anatomical regions: head and neck (n = 129), upper extremity (n = 47), and lower extremity (n = 24). Flaps were transferred as free (n = 189) and pedicled (n = 11). Overall flap survival was 96 percent. Flap variants used included chimeric flap (n = 11) and dual skin paddle (n = 2). Plantaris tendon and saphenous/sural nerve graft were harvested in conjunction in 20 and seven patients, respectively. In 5 percent of the cases harvested in the conventional manner, a reliable perforator could not be found. CONCLUSIONS: The medial sural artery perforator flap is a reliable, alternative workhorse flap for nearly any small- to medium-size defect. It can be harvested as free or pedicled and the option to include multiple tissue components further expands its versatility. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

[The state of the art for arterial coronary artery bypass grafting].

The selection of conduit has always been one of the most perennially debated topic in the field of coronary artery bypass grafting (CABG) . Arterial grafts have demonstrated excellent biological characteristics and long-term patency in CABG. Clinical observations and randomized clinical trials over the past two decades have shown that the internal thoracic artery is the gold standard graft. Multi-arterial and total-arterial CABG significantly improves patients' long-term survival, but there are technical challenges and concerns of sternal complication. Currently multi-arterial and total-arterial CABG are strongly advocated and increasingly applied worldwide. Several guidelines have been published and updated, as well as Chinese expert consensus. Coronary surgery in China is paving anupper stage of quality improvement. Arterial coronary artery bypass grafting should be carried out more broadly in China as evidence accumulation and excellent long-term clinical results.