Mechanical, structural, and physiologic differences between above and below-knee human arteries

Peripheral Artery Disease (PAD) affects the lower extremities and frequently results in poor clinical outcomes, especially in the vessels below the knee. Understanding the biomechanical and structural characteristics of these arteries is important for improving treatment efficacy, but mechanical and structural data on tibial vessels remain limited. We compared the superficial femoral (SFA) and popliteal (PA) arteries that comprise the above-knee femoropopliteal (FPA) segment to the infrapopliteal (IPA) anterior tibial (AT), posterior tibial (PT), and fibular (FA) arteries from the same 15 human subjects (average age 52, range 42-67 years, 87 % male). Vessels were imaged using μCT, evaluated with biaxial mechanical testing and constitutive modeling, and assessed for elastin, collagen, smooth muscle cells (SMCs), and glycosaminoglycans (GAGs). IPAs were more often diseased or calcified compared to the FPAs. They were also twice smaller, 53 % thinner, and significantly stiffer than the FPA longitudinally, but not circumferentially. IPAs experienced 48 % higher physiologic longitudinal stresses (62 kPa) but 27 % lower circumferential stresses (24 kPa) and similar cardiac cycle stretch of <1.02 compared to the FPA. IPAs had lower longitudinal pre-stretch (1.12) than the FPAs (1.29), but there were no differences in the stored elastic energy during pulsation. The physiologic circumferential stiffness was similar in the above and below-knee arteries (718 kPa vs 754 kPa). Structurally, IPAs had less elastin, collagen, and GAGs than the FPA, but maintained similar SMC content. Our findings contribute to a better understanding of segment-specific human lower extremity artery biomechanics and may inform the development of better medical devices for PAD treatment. STATEMENT OF SIGNIFICANCE: Peripheral Artery Disease (PAD) in the lower extremity arteries exhibits distinct characteristics and results in different clinical outcomes when treating arteries above and below the knee. However, their mechanical, structural, and physiologic differences are poorly understood. Our study compared above- and below-knee arteries from the same middle-aged human subjects and demonstrated distinct differences in size, structure, and mechanical properties, leading to variations in their physiological behavior. These insights could pave the way for creating location-specific medical devices and treatments for PAD, offering a more effective approach to its management. Our findings provide new, important perspectives for clinicians, researchers, and medical device developers interested in treating PAD in both above- and below-knee locations.

Evaluation of Arterial and Venous Allografts in Subinguinal Bypasses

BACKGROUND

Autologous saphenous vein is the preferred conduit for below-the-knee bypasses in patients with critical limb-threatening ischemia. Alternative graft must be considered for patients without (autologous saphenous vein). The aim of this article is to evaluate the mid-term performance of arterial allograft (AA) and venous allograft (VA) used as alternative conduits.

METHODS

This retrospective study included patients with critical limb-threatening ischemia, with or without a history of homolateral femoropopliteal bypass, and no autologous veins were available who underwent infrainguinal arterial reconstructions using VA or AA from 2008 to 2018. Patients undergoing revision operations for infected bypasses were excluded. Primary patency (PP), primary assisted patency, secondary patency, major amputation, and death from any cause were the endpoints. For each event, a set of analyses were performed.

RESULTS

Overall, 111 patients (63 VAs and 48 AAs) were included, with 108 having below-the-knee bypass. The median follow-up time was 27.8 months (15.6-37.4). The difference in PP between the 2 allograft types was significant (P = 0.049), with 65.9% (43.7-81.0), 44.1% (24.2-62.3), and 44.1% (24.2-62.3) in the AA group, respectively, at 6, 12, and 18 months, whereas 55.6% (40.0-68.6), 46.0% (30.6-60.2), and 33.2% (18.2-49.0) in the VA group. The choice of an AA over a VA was an independent factor associated with patency (for PP: hazard ratio [HR] = 0.43 [0.24-0.75], P = 0.003); primary assisted patency: HR = 0.52 (0.30-0.89], P = 0.018; and secondary patency: HR = 0.49 (0.27-0.88), P = 0.016. The allograft type did not affect either the incidence of major amputation or death from any cause (respectively, HR = 1.20 [0.49-2.93], and 0.88 [0.37-2.14]).

CONCLUSIONS

The nature of the allograft appears to influence the patency of infrainguinal reconstruction, but not the course of the disease. Performant alternative grafts answering infectious issues are needed.

Venous Reconstruction in Extremity Soft Tissue Sarcoma Is Not Essential

OBJECTIVE

Limb salvage is an important concern following complete oncologic resection for extremity soft tissue sarcoma (STS). Vascular reconstruction is essential for limb salvage. The purpose of this study was to evaluate the outcomes of vascular reconstruction in patients with extremity STS.

METHODS

This is a retrospective, multi-center, case series of consecutive patients who underwent vascular reconstruction during extremity STS resection at 2 major centers in Korea. Demographics, reconstruction methods, type of conduit, surgical complications, graft patency, limb salvage rate, and patient survival were reviewed.

RESULTS

From March 2005 to December 2020, 43 patients underwent vascular reconstructions during STS resection. Among the patients, 22 (51.2%) received arterial only, and 21 (48.8%) received simultaneous arterial and venous reconstructions. For the types of conduits, autologous saphenous veins (56.2%), artificial grafts (26.3%), and cryopreserved allografts (15.8%) were used. During a median follow-up of 23.8 months (interquartile range; 7.7-54.5), the overall primary patency of the reconstructed vessels was significantly higher in arteries than in veins (82.5% vs 56.3% at 12 months, P < .001). According to the type of conduit, the primary patency rate of autogenous vein seemed higher in venous reconstruction, however, there was no statistical significance in both arterial and venous reconstruction. There was no significant difference in primary arterial patency rate (P = .132) or incidence of surgical complications including postoperative edema or wound problem whether or not simultaneous venous reconstruction was performed with arterial reconstruction. The overall limb salvage rate and patient survival were 97.4%, 95.1%, and 89.4% and 91.9%, 81.7%, and 65.4% at 12, 24, and 36 months, respectively.

CONCLUSIONS

Patency rates were poorer in venous reconstruction than in arterial reconstruction. In terms of arterial patency and postoperative complication, the role of simultaneous arterial and venous reconstruction seems not essential, however, it needs to be evaluated in future studies.

Comparison of arterial and venous allograft bypass in chronic limb-threatening ischemia

INTRODUCTION

Femoro-popliteal bypass with autologous vascular graft is a key revascularization method in chronic limb-threatening ischemia (CLTI). However, the lack of suitable autologous conduit may occur in 15-45% of the patients, necessitating the implantation of prosthetic or allogen grafts. Only little data is available on the outcome of allograft use in CLTI.

AIMS

Our objective were to evaluate the long term results of infrainguinal allograft bypass surgery in patients with chronic limb-threatening ischemia (CLTI) and compare the results of arterial and venous allografts.

METHODS

Single center, retrospective study analysing the outcomes of infrainguinal allograft bypass surgery in patients with CLTI between January 2007 and December 2017.

RESULTS

During a 11-year period, 134 infrainguinal allograft bypasses were performed for CLTI [91 males (67.9%)]. Great saphenous vein (GSV) was implanted in 100 cases, superficial femoral artery (SFA) was implanted in 34 cases. Early postoperative complications appeared in 16.4% of cases and perioperative mortality (<30 days) was 1.4%. Primary patency at one, three and five years was 59%, 44% and 41%, respectively, while secondary patency was 60%, 45% and 41%, respectively. Primary patency of the SFA allografts was significantly higher than GSV allografts (1 year: SFA: 84% vs. GSV: 51% p = 0,001; 3 years: SFA: 76% vs. GSV: 32% p = 0,001; 5 years: SFA: 71% vs. GSV: 30% p = 0.001). Both primary and secondary patency of SFA allograft implanted in below-knee position were significantly higher than GSV bypasses (p = 0.0006; p = 0.0005, respectively). Limb salvage at one, three and five years following surgery was 74%, 64% and 62%, respectively. Long-term survival was 53% at 5 years.

CONCLUSION

Allograft implantation is a suitable method for limb salvage in CLTI. The patency of arterial allograft is better than venous allograft patency, especially in below-knee position during infrainguinal allograft bypass surgery.

Long-term outcome in pediatric surgical bypass grafting after traumatic injury and tumor resection: retrospective cohort analysis

Vascular bypass surgery in children differs significantly from adults. It is a rarely performed procedure in the setting of trauma and tumor surgery. Besides technical challenges to reconstruct the small and spastic vessels, another concern in bypass grafting is the adequate limb length growth over time. The primary aim of this study was to assess long-term outcome after pediatric bypass grafting, in a single academic center, focusing on potential effects on limb development. In this retrospective cohort analyses we included all pediatric patients undergoing vascular bypass grafting at our department between 2002 and 2017. All patients ≤ 18 years suffered a traumatic injury or underwent a tumor resection of the lower or upper limb. The youngest female patient was 0.4 years, the youngest male patient was 3.5 years. During the observation period, 33 pediatric patients underwent vascular repair, whereby 15 patients underwent bypass grafting. Median overall follow-up was 4.7 years (IQR ± 9). 8 patients (53%) had a traumatic injury (traumatic surgery group) and 7 patients had a planned orthopedic tumor resection (orthopedic surgery group). In 13/15 (87%) a great saphenous vein (GSV) graft and in 2/15 (13%) a Gore-Tex graft was used for bypassing. Both Gore-Tex grafts showed complete occlusion 12 and 16 years after implantation. No patient died in the early postoperative phase (< 30 days), however 3/7 (43%) in the orthopedic group died during follow-up. Revision surgery had to be performed in 1/15 (7%) patients. A functional use of the extremity was reported in all patients. Normal limb length growth according to the contralateral site, and therefore bypass growth, could be documented in 14/15 patients. Children are surgically challenging. In our study, surgery by a specialized vascular surgery team using GSV grafts led to adequate limb length and bypass growth, and we observed no functional restrictions.

Comparative efficacy of autologous versus cadaveric saphenous vein grafts in cerebral revascularization surgery

OBJECTIVE

Cerebral bypasses are performed for the purpose of either flow augmentation for ischemic cerebrovascular disease or flow replacement for vessel sacrifice during complex aneurysm or tumor surgery. Saphenous vein grafts (SVGs) are commonly used interposition grafts. The authors of this study sought to compare the efficacy of autologous versus cadaveric SVGs in a large series of cerebral bypasses using interposition vein grafts with long-term angiographic follow-up.

METHODS

All intracranial bypass procedures performed between 2001 and 2018 were reviewed. Demographic, clinical, angiographic, and operative data were recorded and then analyzed according to SVG type.

RESULTS

A total of 308 consecutive intracranial bypasses were performed during the study period, 53 (17.2%) of which were bypasses with an interposition SVG (38 autologous, 15 cadaveric). At a median follow-up of 2.2 months (IQR 0.2–29.1), 39 (73.6%) bypasses were patent (26 [68.4%] autologous, 13 [86.7%] cadaveric, p = 0.30). Comparing autologous and cadaveric SVG recipients, there were no statistically significant differences in age (p = 0.50), sex (p > 0.99), history of smoking (p = 0.75), hypertension (p > 0.99), diabetes mellitus (p = 0.13), indication for bypass (p = 0.27), or SVG diameter (p = 0.65). While there were higher intraoperative (autologous, 100.0 ml/min, IQR 84.3–147.5; cadaveric, 80.0 ml/min, IQR 47.3–107.8; p = 0.11) and postoperative (autologous, 142.2 ml/min, IQR 76.8–160.8; cadaveric, 92.0 ml/min, IQR 69.2–132.2; p = 0.42) volumetric flow rates in the autologous SVGs compared to those in the cadaveric SVGs, the difference between the two groups did not reach statistical significance. In addition, the blood flow index, or ratio of postoperative to intraoperative blood flow, for each bypass was similar between the groups (autologous, 1.3, IQR 0.9–1.6; cadaveric, 1.5, IQR 1.0–2.3; p = 0.37). Kaplan-Meier estimates showed no difference in bypass patency rates over time between autologous and cadaveric SVGs (p = 0.58).

CONCLUSIONS

Cadaveric SVGs are a reasonable interposition graft option in cerebral revascularization surgery when autologous grafts are not available.

Mechanically tuned vascular graft demonstrates rapid endothelialization and integration into the porcine iliac artery wall

Mechanical properties of vascular grafts likely play important roles in healing and tissue regeneration. Healthy arteries are compliant at low pressures but stiffen rapidly with increasing load, ensuring sufficient volumetric expansion without overstretching the vessel. Commercial synthetic vascular grafts are stiff and unable to expand under physiologic loads, which may result in altered hemodynamics, deleterious cellular responses, and compromised clinical performance. The goal of this study was to develop an Elastomeric Nanofibrillar Graft (ENG) with artery-tuned nonlinear compliance and compare its healing responses to conventional expanded polytetrafluoroethylene (ePTFE) grafts in a porcine iliac artery model. Human and porcine iliac arteries were mechanically characterized, and an ENG with similar properties was created by utilizing residual strains within electrospun nanofibers. The ENG was tested for implantation suitability and implanted onto n = 5 domestic swine iliac arteries, with control ePTFE grafts implanted onto the contralateral iliac arteries. After two weeks in vivo, all iliac arteries and grafts remained patent with no signs of thrombosis or dilation. The mechanically tuned ENG implants exhibited a more confluent CD31-positive cell monolayer (1.53 ± 0.73 µm²/mm vs 0.52 ± 0.55 µm²/mm, p = 0.042) on the graft lumenal surface and a higher fraction of αSMA-positive cells (16.2 ± 8.6% vs 1.4 ± 0.7%, p = 0.018) within the graft wall than the ePTFE controls. Despite heavy cellular infiltration, the ENG retained its artery-like mechanical characteristics after two weeks in vivo. These short-term results demonstrate potential advantages of mechanically tuned biomimetic vascular grafts over standard ePTFE grafts. STATEMENT OF SIGNIFICANCE: Off-the-shelf synthetic vascular grafts are often the only option available for treating advanced stages of vascular disease. Despite significant efforts devoted to improving their biochemical characteristics, synthetic peripheral arterial grafts continue to demonstrate poor clinical outcomes leading to costly reinterventions. Here, we hypothesized that a synthetic vascular graft with elastomeric mechanical properties tuned to a healthy peripheral artery promotes better healing responses than a synthetic stiff graft. To test this hypothesis, we developed an Elastomeric Nanofibrillar Graft (ENG) with artery-tuned mechanical properties and compared its performance to a commercial ePTFE graft in a preclinical porcine iliac artery model. Our results suggest that mechanically tuned ENGs can offer better healing responses, potentially leading to better clinical outcomes for peripheral arterial repairs.

Immunological Aspects Involved in the Degeneration of Cryopreserved Arterial Allografts

Introduction: Cryopreserved arterial allografts have remained an option in patients requiring distal revascularization or associated with vascular infection, in the absence of a valid autogenous saphenous vein. The objective of this study is to describe the different clinical, anatomopathological, and immunological findings related to vascular transplant rejection.

Methods: In a prospective trial, 35 patients who underwent cryopreserved allogeneic arterial bypass were studied, including demographics and conduit patency. Anti-HLA antibody production was stablished prior to the surgery, 7 days, 1, 3 months, and every 3 months since. Clinical and ultrasound evaluation was added after the first month. Donor HLA-typing was retrieved whenever available, allowing for the characterization and quantification of donor specific antibodies. Cytotoxic crossmatch test was also performed. A second group of patients with allograft degenerations registered during the follow up period was studied. In this group, exclusively for aneurysm description and histopathological analysis, they were included those degenerated vascular transplants from the original series, but also those implanted prior to the beginning of the study and degraded during follow up.

Results: All patients studied displayed an increase in anti-HLA antibodies one month after the intervention, regarding bypass patency. In total, 14 patients fulfilled requirements for the study of donor specific antibodies, equally showing IgG production detectable one month after surgery. The presence of complement-fixing antibodies was also confirmed. Antibody levels were not related to graft degeneration. No specific immune markers able to predict aneurysmal development and evolution were found. From the original group, 3 patients suffered aneurysmal degeneration during follow up, together with 9 bypasses previously implanted. Average time until the first degeneration was 33 ± 19.7 months, with 30.6 ± 17.7 and 54.5 ± 2.5 months for a second and third degeneration, when occurring. Therefore, subsequent vascular transplants frequently augmented the time for new degenerations, despite increasing sensibilization. Samples from eight degenerated allografts were available for analysis, unexpectedly showing inflammatory infiltrate in only four cases and immune complex deposition in 7.

Conclusions: Immune response against vascular transplants was confirmed in all cases, but chronic rejection did not necessarily provoke bypass degradation or reduced the time for new aneurysms to develop in subsequent allografts.

[The place of arterial allograft in reconstructive surgery of the main arteries of the lower extremities]

Critical limb ischemia, especially in the absence of autologous vein, prosthetic and native vascular infections are isolated diseases for which there currently doesn't have best surgical treatment. Vascular allografts may be the treatment of choice for these patients. In this analysis, we tried to reflect the directions of development of vascular allotransplantation, global trends related to indications for their use, methods of conservation, degradation and endothelial dysfunction. At the present time there doesn't have meta-analyzes on the efficiency of using arterial allografts or other options for implantation (synthetic graft, xenografts) for critical limb ischemia and graft and native infections. Now it is wrong to recommend using them always. Further studies of their performance are necessary. In addition, development of graft control techniques is also needed when rejection develops. Currently, there are no special diagnostic markers, the assessment of which could save patients with immune-mediated dilatation and dysfunction of allografts.

Microsurgical Salvage of Acute Lower Limb Ischemia after Iatrogenic Femoral Injury during Orthopedic Surgery in a Pediatric Patient

Acute lower limb ischemia (ALLI) in the pediatric population is rare but may lead to limb loss and life-long complications. We report the technique and outcomes of microsurgical salvage of ALLI in a preterm newborn after open reduction of congenital hip dysplasia. A 2-month-old girl was born premature at week 36 with congenital bilateral hip dysplasia. The initial management attempted was conservative and entailed placement of bilateral Von Rosen splints. The treatment was successful on the left side, but the patient had recurrent unstable hip dislocation on the right side. Subsequently, 2 attempts at close reduction under general anesthesia were done and both were unsuccessful in maintaining the right hip in the acetabulum. Therefore, an open reduction of the right hip was planned through a medial/obturator approach. During the surgical procedure, the neurovascular femoral bundle (including the superficial femoral artery [SFA], femoral vein [FV], and femoral nerve) was accidently transected with subsequent development of ALLI. Therefore, the FV was harvested distally to the injury site and a 4-cm long healthy segment was obtained. It was reversed, flushed with heparin, spatulated at both extremities, and interposed to the SFA in end-to-end fashion using two 9/0 polypropylene interrupted sutures under microscope. Reperfusion of the limb was noted immediately after releasing the vascular clamps. The final ischemia time at completion of the surgical procedure was 6 hr. Thereby, prophylactic 4-compartment fasciotomies were performed in the right leg. The patient tolerated the procedure well and the postoperative clinical course was free from adverse events. Duplex ultrasound examination at 6 weeks after the intervention confirmed sustained clinical success and showed no signs of venous thromboembolism. At the same time, X-ray examination of the right hip confirmed adequate and stable reduction of the joint in the acetabulum. ALLI due to accidental arterial injury during orthopedic surgical procedures for congenital defects in newborns is a rare but potentially devastating complication. Microsurgical salvage is a safe, feasible, and effective option to restore limb flow. Multidisciplinary expertise and meticulous technique are mandatory in order to achieve satisfactory and durable outcomes.

Treatment of lower limb arterial disease by Dardik graft: It takes one to know one

OBJECTIVE

To perform a comprehensive literature review on outcomes achieved with the historical Dardik graft, illustrated with a case report of a patient with 13-years primary patency and limb salvage.

METHODS

A comprehensive literature review was performed through MedLine (PubMed.gov, U.S. National Library of Medicine, National Institute of Health) from 1976 to 2018 using search terms (Umbilical Vein Graft), (Dardik graft), (Glutaraldehyde stabilized human umbilical vein [HUV]) and (HUV) to collected data on clinical use of HUV. Only papers in English and reporting adequate information about indication for surgery, short- and long-term patency and complication rate were included.

RESULTS

Data about a total of 899 patients (977 limbs) were available. Overall, 45% of patients (438 limbs) underwent HUV implantation for critical limb ischemia (rest pain or tissue loss) or for disabling claudication in 12.2% of cases (120 limbs). Others indication for surgery were acute onset limb ischemia, popliteal aneurysms or aneurysmal degeneration of a previously implanted synthetic graft. At a mean follow-up of 4.3 years (range 3-6 years), primary patency and secondary patency were 61.3% and 61%, respectively. Aneurisms formation was detected in 3% of cases (21 limbs), graft's infection in 24.4% of cases (31 limbs) and graft's thrombosis in 25.5% of cases (193 limbs).

CONCLUSION

This article provide a historical review of the use, outcomes and complications of HUV. Even though it is no longer commercially available, the knowledge of this type of substitute still remains inspirational for the development of innovative vascular conduits and fundamental for the new generations of physician both in diagnostics and in the management of complications.

Ten Year Experience of Using Cryopreserved Arterial Allografts for Distal Bypass in Critical Limb Ischaemia

OBJECTIVE/BACKGROUND

In critical limb ischaemia (CLI), current guidelines recommend revascularisation whenever possible, preferentially through endovascular means. However, in the case of long occlusions or failed endovascular attempts, distal bypasses still have a place. Single segment great saphenous vein (GSV), which provides the best conduit, is often not available and currently there is no consensus about the best alternative graft.

METHODS

From January 2006 to December 2015, 42 cryopreserved arterial allografts were used for a distal bypass. Autologous GSVs or alternative autologous conduits were unavailable for all patients. The patients were observed for survival, limb salvage, and allograft patency. The results were analysed with Kaplan-Meier graphs.

RESULTS

Estimates of secondary patency at one, two and five years were 81%, 73%, and 57%, respectively. Estimates of primary patency rates at one, two and five years were 60%, 56%, and 26%, respectively. Estimates of limb salvage rates at one, two and five years were 89%, 89%, and 82%, respectively. Estimates of survival rates at one, two and five years were 92%, 76% and 34%, respectively. At 30 days, major amputations and major adverse cardiac events were one and zero, respectively. Six major amputations occurred during the long-term follow up.

CONCLUSION

Despite a low primary patency rate at two years, the secondary patency of arterial allografts is acceptable for distal bypasses. This suggests that cryopreserved arterial allografts are a suitable alternative for limb saving distal bypasses in the absence of venous conduits, improving limb salvage rates and, possibly, quality of life.

Peripheral artery reconstructions using cryopreserved arterial allografts in infected fields

OBJECTIVE

Cryopreserved human arterial allografts are a recognized acceptable alternative for vascular reconstruction when other traditional conduits are either unavailable or contraindicated. We reviewed our experience using cryopreserved arterial allografts for peripheral artery reconstructions in contaminated and infected surgical fields.

METHODS

A single-center, retrospective review was conducted of 57 patients who underwent a peripheral vascular reconstruction using a cryopreserved arterial allograft from January 2002 through July 2017. Indications for repair included removal of infected prosthetic bypass (n = 29), revascularizations in contaminated fields (n = 11), primary arterial repair in the setting of infection (n = 10), and infected vascular closure devices (n = 7). Aorta-based repairs were excluded. Demographics, index procedural details, postoperative complications, and conduit patency were analyzed. Primary end points included conduit-related mortality and graft failure as measured by reinfection, hemorrhage, or aneurysmal degeneration. Mean follow-up for the study is 27.8 months (range, 2-125 months).

RESULTS

A total of 57 peripheral vascular reconstructions using cryopreserved arterial allografts were performed during the 15-year period. Among the 22 women and 35 men treated, the mean age was 61 years. The vascular beds involved included iliofemoral (n = 39), femoropopliteal or femoral-distal (n = 10), axillosubclavian or brachial (n = 2), mesenteric (n = 3), and carotid (n = 3) arteries. Adjunctive muscle flap coverage of the allograft conduit was performed in the majority of cases (61%; n = 35). The 30-day mortality was 9%; one death was directly related to conduit insertion. The 30-day conduit-related complication rate was 14% and included hemorrhage from the graft requiring return to the operating room (n = 4) and graft infection (n = 4). The late conduit-related complication rate was 15.8% and included graft infection (n = 1), graft thrombosis (n = 3), major amputation resulting from conduit failure (n = 1), pseudoaneurysm degeneration requiring repair (n = 2), graft hemorrhage (n = 1), and symptomatic graft stenosis (n = 1).

CONCLUSIONS

A cryopreserved arterial allograft is a useful alternative conduit for peripheral vascular reconstruction in infected or contaminated surgical fields when other autologous or prosthetic conduits are either unavailable or contraindicated. In the immediate postoperative period, these repairs demonstrate acceptable resistance to graft failure and reinfection, particularly in conjunction with adjunctive rotational muscle flap coverage. Late conduit-related complications appear to be infrequent.

Long-term outcomes after pediatric peripheral revascularization secondary to trauma at an urban level I center

OBJECTIVE

The purpose of this investigation was to determine our limb-related contemporary pediatric revascularization perioperative and follow-up outcomes after major blunt and penetrating trauma.

METHODS

A retrospective review was performed of a prospectively maintained pediatric trauma database spanning January 2010 to December 2017 to capture all level I trauma activations that resulted in a peripheral arterial revascularization procedure. All preoperative, intraoperative, and postoperative continuous variables are reported as a mean ± standard deviation; categorical variables are reported as a percentage of the population of interest.

RESULTS

During the study period, 1399 level I trauma activations occurred at a large-volume, urban children's hospital. The vascular surgery service was consulted in 2.6% (n = 36) of these cases for suspected vascular injury based on imaging or physical examination. Our study population included only patients who received an arterial revascularization, which was performed in 23 of the 36 consultations (1.6% of total traumas; median age, 11 years). These injuries were localized to the upper extremity in 60.9% (n = 14), lower extremity in 30.4% (n = 7), and neck in 8.7% (n = 2). The mean Injury Severity Score in the revascularized cohort was 14.0 (±7.6). Bone fractures were associated with 39.1% of the vascular injuries (90% of blunt injuries). Restoration of in-line flow was achieved by an endovascular solution in one patient and open surgery in the remainder, consisting of arterial bypass in 59.1% and direct repair in 40.9%. Within 30 days of the operation, we observed no deaths, no infections of the arterial reconstruction, and no major amputations. One patient required perioperative reintervention by the vascular team secondary to the development of a superficial seroma without evidence of graft involvement. Mean follow-up in our cohort was 43.3 (±35.4) months. During this phase, no additional deaths, amputations, chronic wounds, or limb length discrepancies were observed. All vascular repairs were patent, and all but one patient reported normal function of the affected limb at the latest clinic visit.

CONCLUSIONS

Traumatic peripheral vascular injury is rare in the pediatric population but is often observed secondary to a penetrating force or after long bone fracture. However, contemporary perioperative and long-term outcomes after surgical revascularization are excellent as demonstrated in this institutional case series.

Cryopreserved saphenous vein as a last-ditch conduit for limb salvage

OBJECTIVE

In patients lacking autogenous vein suitable for infrainguinal bypass, cryopreserved saphenous vein (CSV) allograft (CryoLife, Inc, Kennesaw, Ga) may be an acceptable alternative. The purpose of this study was to examine outcomes of CSV conduit for infrainguinal revascularization.

METHODS

Between February 2008 and August 2015, 70 patients underwent infrainguinal bypass grafts in 73 limbs using CSV. All patients lacked suitable arm or leg vein. Demographic data and patient outcomes were retrospectively collected using electronic medical records.

RESULTS

The mean age of our cohort was 70 ± 14 years, and 36 (51%) were male; 47 (67%) were white, 39 (56%) had coronary artery disease, 27 (39%) had diabetes, 56 (80%) had hypertension, and 50 (71%) were former or current smokers. Median follow-up was 304 days (interquartile range, 130-991 days). Indications for the index operation included rest pain (27%), tissue loss (55%), and prosthetic graft infection (18%); 62 of 73 (85%) bypasses were performed for critical limb ischemia, and 45 of 73 (62%) were redo operations. Distal targets included superficial femoral artery or popliteal (38%), tibial (55%), and pedal (7%). All grafts had a minimum diameter of 3 mm. At 30 days, 55 of 64 grafts (86%) were patent; 9 were lost to early follow-up. The only significant risk factors associated with 30-day failure were ABO mismatch (43% vs 10%; P = .05) and donor blood type B or AB (40% vs 9%; P = .03). Estimated overall 1-year primary patency was 35%. In a multivariate analysis, nonblack race (P = .05), donor B or AB blood type (P = .01), and bypass to a tibial or pedal target (P = .05) were independently associated with loss of primary patency. There were 20 (27%) major amputations, and all grafts in these limbs had occluded at the time of amputation. Of the 33 limbs with ischemic tissue loss that had long-term follow-up, 17 of 33 (52%) went on to graft occlusion, 10 of 33 (30%) had a major amputation, and 24 of 33 (73%) had complete healing of the index wound.

CONCLUSIONS

In the setting of a multidisciplinary team with aggressive wound care, CSV may be a reasonable choice for infrainguinal revascularization in patients with ischemic tissue loss who lack autogenous conduit. However, poor midterm to long-term patency suggests that optimal selection of patients is needed to derive meaningful clinical benefit.

Endovascular Treatment of Aneurysmal Deterioration in Peripheral Arterial Allografts

Purpose:

To report endovascular treatment of 2 patients with aneurysmal deterioration of peripheral arterial allografts.

Case Report:

Two men (65 and 64 years old) who had undergone an arterial allograft reconstruction for infection of prosthetic infrapopliteal bypass grafts 5 and 7 years ago, respectively, were diagnosed with asymptomatic aneurysmal deterioration of the allografts. Stent-graft repair was successful in both cases, completely excluding the aneurysms. At ≥1 year, continued aneurysm exclusion was confirmed by duplex scan, with no evidence of endoleak, migration, or stenosis.

Conclusion:

Endovascular treatment may be a useful therapeutic option when treating patients with late peripheral allograft deterioration.

A novel approach of arteriovenous fistula formation in cultivation of an arm vein for use in infrainguinal surgical bypass grafting

Autologous vein is preferable for use in lower limb arterial bypass rather than synthetic graft material. Suitable vein for grafting is often limited, particularly in patients who have had previous cardiac bypass grafting or varicose veins surgery. This case report describes the use of arteriovenous fistula formation to cultivate an arm vein of a suitable diameter for use in femorotibial bypassing.

Development of a control system for artificially rehabilitated limbs: a review

Development of an advanced control system for prostheses (artificial limbs) is necessary to provide functionality, effectiveness, and preferably the feeling of a sound living limb. The development of the control system has introduced varieties of control strategies depending on the application. This paper reviews some control systems used for prosthetics, orthotics, and exoskeletons. The advantages and limitations of different control systems for particular applications have been discussed and presented in a comparative manner to help in deciding the appropriate method for pertinent application.

Vascular grafts

Autogenous vein is the conduit of choice in the surgical creation of bypasses of small-to-medium-caliber vessels in patients with peripheral occlusive arterial disease and will remain so for the near future. The success rate of bypasses using conduits of diameters greater than 6 mm has been excellent, whereas the majority of bypasses using smaller conduits fail within 5 years. In addition, due to a steep increase in rates of diabetes and decreasing cardiovascular mortality rates, increasing challenges are presented by this population. These facts have motivated much of the research in the cardiovascular arena over the past four decades, with improved techniques and new materials. Strategies to improve outcomes include the use of alternative materials including autologous, nonautologous and prosthetic grafts, utilizing different methods for their harvesting and preservation; tissue engineering, using either polymer- or biological-based scaffolds for cell seeding; endovascular methodologies; and gene therapy. This report presents an overview of the several options currently available in the management of patients with peripheral arterial occlusive disease, as well as the ongoing research directed towards the creation of an artificial engineered vessel, discussing experimental work in which endothelial cells have been seeded on different scaffolds and finally the potential application of gene therapy in the field of vascular reconstruction.

A cost-effectiveness analysis of infrainguinal bypass in the absence of great saphenous vein conduit

BACKGROUND

Good-quality great saphenous vein (GSV) is the preferred conduit for infrainguinal surgical revascularizations, but it is not available in all patients. We sought to identify the alternative conduit that would maximize cost-effectiveness in the context of infrapopliteal bypass for critical limb ischemia and nonhealing foot wounds.

METHODS

A Markov model was used to create a detailed simulation of 10-year outcomes in a hypothetical Edifoligide for the Prevention of Infrainguinal Vein Graft Failure (PREVENT) III-type patient cohort undergoing infrainguinal bypass for nonhealing foot wounds. The following management options were evaluated: (1) conservative therapy (local wound care, amputation as needed); (2) primary amputation; (3) bypass with autologous alternative vein (AAV), including arm or lesser saphenous vein; (4) bypass with GSV <3 mm in diameter; (5) bypass with polytetrafluoroethylene (PTFE); (6) cryopreserved venous allograft; and (7) cryopreserved arterial allograft. Estimates of 10-year total costs were incorporated into the model. Cost-effectiveness was measured in terms of incremental United States dollars per additional year of ambulation.

RESULTS

Bypass with AAV had the highest effectiveness as measured in median years of ambulation. After primary amputation, bypass with PTFE had the lowest total costs. With incremental cost-effectiveness ratios of $5325 and $21,228, bypass with PTFE or AAV appeared to be cost-effective alternatives to conservative therapy for nonhealing ischemic wounds. Primary amputation, GSV <3 mm, and allograft options were dominated (ie, more costly and less effective). Primary amputation was weakly dominated.

CONCLUSIONS

Bypass with PTFE or AAV appears to be a cost-effective option for the management of critical limb ischemia and nonhealing foot wounds when good-quality GSV is not available.

Fifteen years of infrapopliteal arterial reconstructions with cryopreserved venous allografts for limb salvage

OBJECTIVE

The availability of autologous vein grafts remains the limiting factor in infragenual bypass surgery in many patients with critical limb ischemia (CLI). Alternatives such as prosthetic conduits are known to have a poor outcome and most are not resistant to infection. Based on previous experimental work, we started to use cryopreserved saphenous vein allografts for this indication 15 years ago. To evaluate their outcome, we performed a retrospective study of those bypasses with distal anastomosis on a crural or pedal vessel.

METHODS

Between November 1991 and December 2005, 108 cryopreserved great saphenous vein allografts were implanted for in 92 patients (42 women, 50 men) with a mean age of 71 years (range, 39-88 years). All patients received low-dose immunosuppressive therapy for up to 1 year after intervention. Follow-up was conducted until amputation, death, or the end of the study in March 2007.

RESULTS

Nondiabetic atherosclerosis the cause of CLI in 57%, 41% had diabetes, and 2% had Buerger disease. Forty-one conduits were performed for primary reconstructions and 67 for redo reconstructions. During a mean follow-up of 26.4 months, 69 occlusions occurred. Primary and secondary patency rates were 56% and 73% at 1 year, 32% and 60% at 3 years, and 17% and 38.5% at 5 years. Survival rates were 87.4% at 1 year and 64.5% at 5 years. At multivariate analysis, the intake of statins was predictive for improved patency (hazard ratio [HR], 0.09; P = .024) and for prolonged survival (HR, 0.335; P = .045). The presence of diabetes showed a trend for inferior patency (HR, 2.325; P = .116) and for decreased amputation risk (HR, 0.592; P = .078).

CONCLUSION

Cryopreserved saphenous vein allografts are a valuable alternative to prosthetic materials when autologous veins are not available. Our limb salvage and patency rates are higher then those described for prosthetic grafts at the infrapopliteal level in most studies. Moreover, these grafts are resistant to infection when performed for revascularization in patients with an infected ulcer. Better graft and patient selection, better graft surveillance and immunologic matching, and standard use of statins could possibly improve the results even further. Shortage in availability might be a limiting factor for their widespread use.

Non-invasive biomechanical evaluation of implanted human cryopreserved arterial homografts: comparison with pre-implanted cryografts and arteries from human donors and recipients

Native vessels-grafts biomechanical mismatch (BM) is related to graft failure. The BM could be reduced using human cryopreserved/defrosted arteries (cryografts), but post-thaw cryografts' recovery could be associated with an impaired biomechanical behavior. In vitro, we demonstrated that our cryopreservation methods do not affect arteries' biomechanics, but only post-implant studies would allow determining the cryografts' biomechanical performance.

AIM

To characterize the biomechanical properties of implanted cryografts, and to compare them with cryografts pre-implant, recipients' native arteries, and arteries from subjects with characteristics similar to those of the recipients and multiorgan donors (MOD) whose arteries were cryopreserved.

METHODS

Native femoral arteries anastomosed to cryografts, implanted cryografts, and arteries from subjects, recipient-like and MOD-like, were studied. In vitro (pre-implant cryografts) and in vivo non-invasive studies were performed. Arterial pressure, diameter, and wall thickness were obtained to quantify local and regional biomechanical parameters, and to evaluate the arterial remodeling.

CONCLUSION

Implanted cryografts were remodeled, with an increased wall thickness, wall-to-lumen ratio, and wall cross-sectional area. The proximal-distal gradual transition in stiffness remained unchanged. Implanted cryografts were stiffer than MOD-like arteries, but more compliant than recipients' arteries. The cryografts-native arteries biomechanical differences were lesser than those described for venous grafts or expanded polytetrafluoroethylene.

Cold-stored Venous Allografts in the Treatment of Critical Limb Ischaemia

OBJECTIVES

To assess the outcome of cold-stored venous allografts in critically ischemic limbs in patients with no ipsilateral autogenous greater saphenous vein.

DESIGN

A non-randomised, retrospective, single-center study.

METHODS

From September 2000 to June 2006, 46 cold-stored venous allografts obtained during multiorgan harvest were implanted into 44 critically ischaemic limbs of 43 patients. The indication for reconstructions was rest pain (24%) or tissue lost (76%). Sixty-seven percent of procedures were performed as secondary reconstructions, and 61% of veins were anastomosed to tibial or pedal arteries. Thirty-seven percent of patients received prednisone, and 46% tacrolimus as postoperative immunosuppressive therapy. Mean patient follow-up period was 13.3 months (range 1 week to 60 months).

RESULTS

The secondary patency rate for the cohort was 83+/-5.6% at 1 month, 64+/-8.2% at 6 months, 57+/-10.0% at 12 months and 46+/-10.7% at 24 months. Limb salvage rate was 96+/-3.1% at 1 month, 78+/-6.9% at 6 months, 71+/-8.1% at 12 months and 50+/-11.8% at 24 months.

CONCLUSION

Cold-stored venous allografts are an alternative conduit for limb salvage procedures when ipsilateral autogenous vein is unavailable.

Meta-analysis of allograft bypass grafting to infrapopliteal arteries

OBJECTIVE

To determine graft patency and limb preservation after allograft bypass grafting to infrapopliteal arteries for different allograft materials.

DESIGN

Meta-analysis of case series that used survival analysis to describe outcomes.

METHODS

Studies published from 1982 through 2003 were identified from electronic databases and pertinent original articles. Four series of cryopreserved arterial allografts, 10 series of cryopreserved vein allografts, three series of cold-storaged vein allografts, and 16 series of umbilical-cord vein allografts were included in separate random-effects meta-analyses.

RESULTS

A graphical display of pooled survival curves of graft patency showed cold-storaged veins to have the best outcome in the first 4 years, followed by cryopreserved arteries, umbilical-cord veins, and cryopreserved veins. The respective 5-year pooled patency were 24, 21, 30, and 19%. For foot preservation, the best outcome was achieved with cryopreserved arteries followed by cryopreserved veins, umbilical-cord veins, and cold-storaged veins. A reference meta-analysis of polytetrafluoroethlylene grafts occupied the top position for graft patency and the second position for foot preservation.

CONCLUSION

In leg revascularisation for critical ischaemia, graft patency is poor for allografts generally, but using peripheral allografts in repeat attempts at revascularisation is a valid strategy to prevent major amputation. A role for umbilical-cord vein allografts remains uncertain.

Cryopreserved arterial allograft reconstruction for peripheral graft infection

OBJECTIVE

This prospective, observational study evaluated the safety and efficacy of cryopreserved arterial allograft reconstruction in the management of major peripheral arterial graft infections.

METHODS

From April 1996 to May 2003, data from patients with major peripheral arterial graft infection who underwent graft excision and cryopreserved arterial allograft reconstruction were prospectively collected. Arterial allografts were harvested from multiple organ donors and cryopreserved at -80 degrees C. The patients were observed for survival, limb salvage, persistence or recurrence of infection, and allograft patency. The results were calculated with the Kaplan-Meier method.

RESULTS

During the 7-year study period, 17 patients (14 men, 3 women; mean age, 68 years) with major peripheral graft infection underwent graft excision and cryopreserved arterial allograft reconstruction. Eight patients (47%) had systemic sepsis, 5 (29%) had acute ischemia at the time of the allograft reconstruction, and 9 (53%) had experienced anastomotic rupture. Allograft reconstruction was performed as an emergency procedure in 7 patients (41%). There were no perioperative deaths or early amputations. Two patients had allograft ruptures in the groin during the early postoperative period. The mean follow-up period was 34 months (range, 8 to 80 months). There was no persistent or recurrent infection, and none of the patients received long-term (>3 months) antibiotic therapy. Reoperation for allograft revision, excision, or replacement was performed in 2 patients. The 18-month primary and secondary allograft patency rates were 68% and 86%; the overall limb salvage rate was 82% at 2 years.

CONCLUSION

Our experience with cryopreserved arterial allograft in the management of major peripheral bypass graft infection suggests that this technique seems to be a useful option for treating one of the most dreaded vascular complications.

Renal transplantation in patients with abdominal aortic aneurysm--a new surgical approach

An increasing number of abdominal aortic aneurysms occurs in renal failure patients because of an accelerated atherosclerosis process associated with uraemia. When technically feasible, endovascular repair of an abdominal aortic lesion should be considered as the treatment of choice. If a surgical repair is suggested, there are several options to select from. Since November 1999, we performed simultaneous aortic reconstruction using fresh arterial allograft and kidney transplantation in five uraemic patients with asymptomatic abdominal aortic aneurysm. The operative and postoperative course of four patients passed without major complications. One patient had ischaemic colitis early after the operation, which required a partial resection of the colon. One patient died 6 weeks after the operation due to non-vascular causes. In conclusion, the advantage of our single-phase procedure is that both diseases are treated simultaneously during a single hospital stay. Moreover, with our procedure, the risk of vascular graft infection in patients with chronic immunosuppression is low.

Preparation of porcine carotid arteries for vascular tissue engineering applications

Biomaterials derived from tissue continue to offer viable alternatives to synthetic materials when autologous materials are unavailable for transplantation due to their unique chemical and mechanical properties. Tissue processing aims to stabilize the material against host degradation and render it immunologically inert by removing cellular material and crosslinking the structural proteins. It is clear that different approaches taken to achieve these goals have very different chemical and mechanical effects on the material. We describe herein the development of a tissue processing methodology to generate acellular scaffolds for tissue engineering small-diameter vascular grafts. Carotid arteries were isolated from Great White pigs and exposed to various solvent treatments, xylene, butanol, and ethanol to determine optimal parameters for the extraction of host lipids. The tissue was then exposed to a limited proteolysis with trypsin to disrupt cellular protein. This resulted in a controlled digestion that disrupted porcine nuclear DNA and cleared bulk cellular protein, leaving the more resistant structural proteins largely intact and retaining the bulk mechanical properties of the matrix. Histological analysis and scanning electron microscopy illustrated the complete removal of intact cells and nuclear material. The decellularized graft was stabilized by crosslinking with the photooxidative dye methylene green in the presence of 30,000 LUX of broad-band light energy. High-performance liquid chromatography analysis showed that the crosslinked tissue yielded 78.6% less hydroxyproline, compared with control tissue, after 20 h incubation with pepsin. Analysis of the crosslinked vessels' burst-pressure and stress-strain characteristics have shown comparable mechanical properties to those of control vessels. Assessment of in vitro cell adhesion and compatibility was conducted by seeding primary human umbilical vein endothelial cells and adult human vascular smooth muscle cells onto the lumenal and ablumenal surfaces, respectively; these cells were shown to adhere and proliferate under traditional static culture conditions.

Histopathological study of renal transplant artery stenosis: role of rejection and cold ischaemia time in the pathogenesis of intimal hyperplasia in an arterial allograft

INTRODUCTION

Intimal hyperplasia of renal allograft arteries is a cause of hypertension and graft loss and the predisposing factors are poorly understood. We performed a histopathological study focusing on cold ischaemia time and immunological factors and their effect on the donor artery.

METHODS

Primary renal artery branches were obtained from patients undergoing transplant nephrectomy for chronic rejection. Non-transplant patients undergoing nephrectomy served as controls. Clinical information including immunosuppression and rejection episodes, cold ischaemia time and graft survival were collected from the patients' charts. Collagen, smooth muscle cells, T cells, macrophages, and neutrophils were quantified using immunohistochemistry. The intima to media ratio was also calculated using imaging software. Statistical analysis was performed using linear regression and the Mann-Whitney test with P < 0.05 significant.

RESULTS

Nine transplant patients and five controls were included. All transplant patients received maximum immunosuppression according to clinical standards. The median number of acute rejection episodes was 1 (range 0-5). Cold ischaemia time was 24.3 +/- 9.6 h (mean +/- SD). Mean allograft longeviy was 87.4 +/- 72.9 months (mean +/- SD). The intima/media ratio in the transplant group was higher as compared with the control (P = 0.002). The same was true for intima collagen content (P = 0.001) and intima smooth muscle content (P = 0.036). Cold ischaemia time was 19.6 +/- 11.1 h (mean +/- SD) and did not correlate with intima/media ratio. Also the number of rejection episodes did not correlate with the intima/media ratio.

CONCLUSION

Intimal hyperplasia in the allograft artery has a multifactorial aetiology. We were not able to establish an association between intimal hyperplasia and acute rejection episodes or length of cold ischaemia time. It appears that immunosuppression does not prevent the development of intimal hyperplasia.

Meta-analysis of polytetrafluoroethylene bypass grafts to infrapopliteal arteries

CONTEXT

Reports of polytetrafluoroethylene (PTFE) bypass grafting to the infrapopliteal arteries have often used survival analysis of acceptable quality to describe a wide range of long-term results. In theory, these results may be combined if variability between series and time intervals is considered.

OBJECTIVE

Meta-analysis was performed to gain insight into long-term graft patency and foot preservation after PTFE bypass grafting to infrapopliteal arteries.

DATA SOURCE

Studies published from 1982 through 2001 were identified from the PubMed database and pertinent original articles.

STUDY SELECTION

Three investigators selected 43 studies that used survival analysis, reported 2-year patency rates, and included at least 15 bypass procedures. Data extraction and transformation: Based on standard life-tables or survivor curves, an interval success rate was calculated for each month in each series. The monthly success rates were combined across series, enabling construction of pooled survivor curves.

DATA SYNTHESIS

Random-effects meta-analysis yielded 5-year pooled estimates (SE) of 30.5% (7.6%) for primary graft patency, 39.7% (5.5%) for secondary graft patency, and 55.7% (5.0%) for foot preservation. During the entire follow-up, pooled estimates were slightly higher for series of PTFE grafts with adjunctive procedures compared with series of PTFE grafts only. Sensitivity analysis: A simulation using only unfavorable assumptions showed a decrease of less than 5% at 5 years for all outcomes, and smaller differences at subgroup meta-analysis. Funnel plots suggested that publication bias was unlikely.

CONCLUSION

This meta-analysis indicated moderate success for PTFE bypass grafts to infrapopliteal arteries, but the role of adjunctive procedures at the distal anastomosis remains uncertain.

Fresh arterial homograft transplantation: a novel concept for critical limb ischaemia

INTRODUCTION

homografts have been used since the early days of vascular surgery, but have failed to provide long-term success. Arteries supplying organ transplants seldom show signs of biodegradation. We therefore introduced fresh arterial homograft repair with consecutive immunosuppression (ATX).

AIM

to assess feasibility and clinical usefulness of ATX.

SETTING

university teaching hospital.

MATERIAL AND METHOD

conduits were harvested during multi-organ procurement and stored in Custodiol. Implantation followed immediately. Viability of the transplant was documented in all cases. Patients received immunosuppression for the duration of bypass function.

RESULTS

thirteen patients received ATX for critical limb ischaemia (M/F: 11/2, age: 62yr, previous revascularisations: 4.5 (1-8), median run-off index 5, previous organ transplant: n=2. Most bypasses were anastomosed to single tibial or pedal vessels. There was no early failure. Within an average follow up of 12 months there were 6 graft thromboses in 5 patients, successfully revised in 4. Three limbs were lost after 2, 5 and 6 months due to graft failure. Graft rejection was shown in 1 out of 3 explanted grafts.

CONCLUSION

we report a concept, which may circumvent the problem of biologic graft degeneration. Limb salvage was possible in 75% at 12 months in otherwise difficult circumstances.

Prevention of venous graft sclerosis with clopidogrel and aspirin combined with a mesh tubing in a dog model of arteriovenous bypass grafting

OBJECTIVE

to investigate the effect of clopidogrel combined with aspirin or aspirin alone on fibromyointimal hyperplasia (FIMH) in a bypass model with native vein grafts (NVG) and biocompound grafts (BCG).

DESIGN

twelve Beagle dogs were randomised into two equal groups. In each animal NVG and a BCG were interposed in the common carotid arteries. Postoperatively, Group 1 received clopidogrel (200 mg/d) and aspirin (100 mg/d) and Group 2 received aspirin (100 mg/d) alone.

METHODS

the BCG was constructed by sheathing the ipsilateral jugular vein with highly flexible metal mesh tubing. After 30 days the grafts were harvested and pressure fixed. FIMH was determined by morphometry.

RESULTS

the average wall thickness of the BCG was significantly lower than that of the NVG in both groups (0.26 (SD)0.02 mm vs 0.47 (SD)0.15 mm, p = 0.04 and 0.28 (SD)0.05 mm vs 0.70 (SD)0.29 mm, p = 0.01, respectively). For BCG treated with aspirin, the wall cross section area was lower (5.0 (SD)0.6 mm(2)vs 9.1 (SD)3.3 mm(2), p = 0.02) and the lumen larger (25.2 (SD)5.9 mm(2)vs 9.7 (SD)3.4 mm(2), p < 0.01) than for the NVG. There was also a difference in the lumen cross section area of the NVG, which was larger after combined therapy with clopidogrel and aspirin (17.9 (SD)7.8 mm(2)vs 9.7 (SD)3.4 mm(2), p = 0.04).

CONCLUSIONS

in this dog model the sheathing of vein grafts effectively prevents FIMH following bypass surgery. Clopidogrel is effective in NVG.