[Use of allografts in vascular surgery infections]. / Homograftok használata érsebészeti fertozésekben.

With the growing number of patients with vascular endografts, the number of patients with graft infections has also increased. Septic conditions and the choice of grafts are an important challenge in vascular surgery. The aim of this study was to review the literature of the last 7 years showing allograft use in septic conditions in vascular surgery which helps provide insight into the current results of vascular allografts. Data were collected between 1st January 2016 and 31st December 2022. A systematic search was conducted for publications of cryopreserved allograft usage for vascular infection in PubMed and Medline databases. The results of the publications were reviewed based on the following key endpoints: study design, patient's characteristics, mortality rate, graft related complication and reintervention rate, graft patency, limb salvage, graft reinfection rate and survival rate. After a systematic search, 16 publications were included. The articles were divided into two groups: aortic and peripheral. The aortic group included 12 studies covering the data of 542 patients. Early mortality rate (<30 days) was between 2.8% and 42.8%. Allograft-related reintervention rates ranged between 5.9% and 29% (early and late). The rate of graft reinfection was below 10%. 4 studies were included in the peripheral group covering the data of 252 patients. Early mortality rate (<30 days) was between 2.0% and 38%. Allograft-related reintervention rates ranged between 4.0% and 55% (early and late). Reinfection rate was around 4%, but only poor quality data were available. Infections in vascular surgery remain a challenging problem, however, cryopreserved allografts show low reinfection rate and reasonable durability, thus, allografts may be an acceptable option for reconstruction. Orv Hetil. 2023; 164(32): 1256-1262.

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.

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.

[Open and endovascular repair of iliac artery aneurysms]. / Arteria iliaca aneurysma nyitott és endovascularis kezelése.

INTRODUCTION AND AIM: Iliac artery aneurysms make up 2% of all aneurysms. There are only a few data available on the results of surgical treatment, therefore the optimal treatment is unclear. Our objective was the retrospective analysis of the perioperative morbidity and mortality of patients who underwent iliac artery surgery as well as the comparison of elective open surgery and endovascular iliac aneurysm repair (EVIAR). METHOD: Retrospective analysis of patients who underwent surgery for iliac artery aneurysm between 1 January 2005 and 31 December 2014. RESULTS: During the 10-year period, 62 patients with a mean age of 68.9 years underwent elective surgery for iliac artery aneurysm (54 males, 87.1%). In 10 cases acute surgery was performed due to aneurysm ruptures (13.9%), 3 patients died within the perioperative period (30%). Regarding anatomical localisation, aneurysm developed mostly on the common iliac artery (80.6%). As an elective surgery, 35 patients (56.5%) underwent open surgery, 25 (40.3%) underwent EVIAR and other endovascular interventions were performed in 2 cases (3.2%). Postoperative complications (1 patient [4.0%] vs. 17 patients [48.5%]; p<0.001) and intensive care treatment (29 patients [82.8%] vs. 2 patients [8.0%]; p<0.001) were significantly rarer after EVIAR than after open surgery. Furthermore, EVIAR resulted in considerably shorter postoperative hospital stays (4.7 ± 2.3 days vs. 11.8 ± 12.2 days; p = 0.006) and significantly less blood transfusion demand (1 patient [4.0%] vs. 26 patients [74.2%]; p<0.001). There were no significant differences regarding long-term survival rates between EVIAR and open surgery (81.4% vs. 71.4%; p = 0.95). CONCLUSION: In case of the surgical treatment of iliac artery aneurysms, owing to the lower complication rates and shorter postoperative length of stay, EVIAR is primarily recommended. Orv Hetil. 2018; 159(13): 520-525.

[Role of the homograft bypass in extremity inferior's reconstructions]. / Homograftok szerepe az alsó végtagi érrekonstrukciókban.

INTRODUCTION: Vascular homografts are used for limb salvage in cases of graft infection after previous reconstructive vascular surgery or inadequate autologous veins. During multi-organ donation the thoracic aorta segment, aortic bifurcation, iliac arteries, femoral arteries, popliteal arteries, femoral veins and greater saphenous veins can be harvested. Our aim was to optimize the use of homografts by analyzing the results of previous procedures. METHODS: The patient information was processed retrospectively, using the clinical computer system. 162 procedures were performed on 144 patients between 2007 and 2014. The short- and long-term patency, hemorrhagic complication rate, amputation rate and mortality was examined in our study. The location, graft type and length of cryopreservation were taken into consideration. Aortoiliac and femoropopliteal reconstructions with arterial and venous homografts were examined. RESULTS: The mean age of the patients was 63.6 ± 10.7 years, the mean follow-up period was 36 ± 28 months. The primary patency rates at the postoperative 1, 3 and 6 months were 83.7%, 75.0% and 63.4%. In this study the arterial and deep venous homografts had better primary patency rates compared to the superficial venous homografts: at the postoperative 1, 3, 6 months the arterial homograft results were 85.6%, 78.6% and 74.3%, the greater saphenous vein homograft results were 81.4%, 70.4% and 47.7% in the same intervals. CONCLUSION: The reconstructive surgical procedures in septic area mean serious challenge for the vascular surgeons. The AB0 compatibility of the graft and the recipient did not result better long-term outcomes compared to the non-compatible grafts. According to our data the ideal choice of homogenous graft is an arterial homograft which was not cryopreserved longer than 6 months.

Postconditioning in major vascular surgery: prevention of renal failure.

BACKGROUND: Postconditioning is a novel reperfusion technique to reduce ischemia-reperfusion injuries. The aim of the study was to investigate this method in an animal model of lower limb revascularization for purpose of preventing postoperative renal failure. METHODS: Bilateral lower limb ischemia was induced in male Wistar rats for 3 hours by infrarenal aorta clamping under narcosis. Revascularization was allowed by declamping the aorta. Postconditioning (additional 10 sec reocclusion, 10 sec reperfusion in 6 cycles) was induced at the onset of revascularization. Myocyte injury and renal function changes were assessed 4, 24 and 72 hours postoperatively. Hemodynamic monitoring was performed by invasive arterial blood pressure registering and a kidney surface laser Doppler flowmeter. RESULTS: Muscle viability studies showed no significant improvement with the use of postconditioning in terms of ischemic rhabdomyolysis (4 h: ischemia-reperfusion (IR) group: 42.93 ± 19.20% vs. postconditioned (PostC) group: 43.27 ± 27.13%). At the same time, renal functional laboratory tests and kidney myoglobin immunohistochemistry demonstrated significantly less expressed kidney injury in postconditioned animals (renal failure index: 4 h: IR: 2.37 ± 1.43 mM vs. PostC: 0.92 ± 0.32 mM; 24 h: IR: 1.53 ± 0.45 mM vs. PostC: 0.77 ± 0.34 mM; 72 h: IR: 1.51 ± 0.36 mM vs. PostC: 0.43 ± 0.28 mM), while systemic hemodynamics and kidney microcirculation significantly improved (calculated reperfusion area: IR: 82.31 ± 12.23% vs. PostC: 99.01 ± 2.76%), and arterial blood gas analysis showed a lesser extent systemic acidic load after revascularization (a defined relative base excess parameter: 1(st) s: IR: 2.25 ± 1.14 vs. PostC: 1.80 ± 0.66; 2(nd) s: IR: 2.14 ± 1.44 vs. PostC: 2.44 ± 1.14, 3(rd) s: IR: 3.99 ± 3.09 vs. PostC: 2.07 ± 0.82; 4(th) s: IR: 3.28 ± 0.32 vs. PostC: 2.05 ± 0.56). CONCLUSIONS: The results suggest a protective role for postconditioning in major vascular surgeries against renal complications through a possible alternative release of nephrotoxic agents and exerting a positive effect on hemodynamic stability.

Attenuation of skeletal muscle and renal injury to the lower limb following ischemia-reperfusion using mPTP inhibitor NIM-811.

INTRODUCTION: Operation on the infrarenal aorta and large arteries of the lower extremities may cause rhabdomyolysis of the skeletal muscle, which in turn may induce remote kidney injury. NIM-811 (N-metyl-4-isoleucine-cyclosporine) is a mitochondria specific drug, which can prevent ischemic-reperfusion (IR) injury, by inhibiting mitochondrial permeability transition pores (mPTP). OBJECTIVES: Our aim was to reduce damages in the skeletal muscle and the kidney after IR of the lower limb with NIM-811. MATERIALS AND METHODS: Wistar rats underwent 180 minutes of bilateral lower limb ischemia and 240 minutes of reperfusion. Four animal groups were formed called Sham (receiving vehicle and sham surgery), NIM-Sham (receiving NIM-811 and sham surgery), IR (receiving vehicle and surgery), and NIM-IR (receiving NIM-811 and surgery). Serum, urine and histological samples were taken at the end of reperfusion. NADH-tetrazolium staining, muscle Wet/Dry (W/D) ratio calculations, laser Doppler-flowmetry (LDF) and mean arterial pressure (MAP) monitoring were performed. Renal peroxynitrite concentration, serum TNF-α and IL-6 levels were measured. RESULTS: Less significant histopathological changes were observable in the NIM-IR group as compared with the IR group. Serum K+ and necroenzyme levels were significantly lower in the NIM-IR group than in the IR group (LDH: p<0.001; CK: p<0.001; K+: p = 0.017). Muscle mitochondrial viability proved to be significantly higher (p = 0.001) and renal function parameters were significantly better (creatinine: p = 0.016; FENa: p<0.001) in the NIM-IR group in comparison to the IR group. Serum TNF-α and IL-6 levels were significantly lower (TNF-α: p = 0.003, IL-6: p = 0.040) as well as W/D ratio and peroxynitrite concentration were significantly lower (p = 0.014; p<0.001) in the NIM-IR group than in the IR group. CONCLUSION: NIM-811 could have the potential of reducing rhabdomyolysis and impairment of the kidney after lower limb IR injury.

Postconditioning protects skeletal muscle against a long-lasting vascular occlusion.

PURPOSE/AIM OF THE STUDY: Long-lasting lower limb arterial occlusion is a condition with high incidence and complication rates. With the absence of appropriate treatment to cure advanced complications, mortality rates are high. Postconditioning (PC) might be capable of limiting the degree of ischemic-reperfusion (IR) injuries, thus reducing complications and mortality rates. The aim of this study was to evaluate the impact of postconditioning during the first postoperative day on skeletal muscle after a long-lasting arterial occlusion. MATERIALS AND METHODS: Male Wistar rats (n = 72) underwent 8 hr of infrarenal aortic occlusion followed by 2, 6, 12, or 24 hr of reperfusion. In one group of each reperfusion period, postconditioning was applied. Muscle samples were collected for histological examinations. Furthermore, muscle fiber viability and muscle wet-to-dry ratio were assessed. Blood samples were taken for creatine-kinase measurements. RESULTS: Postconditioning strongly reduced morphological injury compared to the corresponding ischemic-reperfusion group (p < .001). Serum creatine-kinase levels showed a peak at 6 hr post-ischemia (IR: 6702.2 ± 797.5; PC: 5523.3 ± 769.3 IU/l) and decreased to normal level by the end of the experiment (Sham: 171.5 ± 71.6; IR: 186.2 ± 82.7; PC: 174.2 ± 72.4 IU/l). Creatine-kinase levels were significantly reduced by postconditioning (p2hr = .028; p6hr = .06; p12hr = .042). A marked decrease in viability was observed in the ischemic-reperfusion groups (2 hr: 11.0 ± 4.1; 6 hr: 10.3 ± 3.6; 12 hr: 9.4 ± 3.3; 24 hr: 8.6 ± 2.8%), whereas with postconditioning, viability was preserved (2 hr: 26.4 ± 5.5; 6 hr: 24.6 ± 4.5; 12 hr: 24.5 ± 6.8; 24 hr: 26.2 ± 6.1%; p < .001); moreover, a significant decrease in the wet-to-dry ratio was achieved (p < .001). CONCLUSION: Postconditioning was able to reduce local complications after a long-lasting lower limb vascular occlusion.

Collateral circulation of the rat lower limb and its significance in ischemia-reperfusion studies.

PURPOSE: Rats are the most commonly used animal model for studies of acute lower limb ischemia-reperfusion. The ischemia induced by arterial clamping may cause milder damage than the application of a tourniquet if the presence of a possible collateral system is considered. METHODS: Male Wistar rats were randomized into three groups: in group A, the muscle weight affected by ischemia was measured; in group B, the severity of muscle damage caused by the application of a tourniquet and by infrarenal aortic occlusion was examined. Blood and muscle samples were taken from group B to assess the serum necroenzyme, potassium and TNF-α levels, as well as the muscle fiber viability and for histological examinations. In group C, the identification of the lower limb collateral system was performed using corrosion casting. RESULTS: Tourniquet application affected the lower muscle mass and resulted in significantly more severe injury compared to infrarenal aortic occlusion. This difference was reflected in the serum necroenzyme, potassium and TNF-α levels. The histological examination and viability assay confirmed these findings. The corrosion casts showed several anastomoses capable of supplying the lower limb. CONCLUSION: Tourniquet application proved to be capable of inducing absolute lower limb ischemia, in contrast to infrarenal aortic ligation, where a rich collateral system is considered to help mitigate the injury.

Postconditioning of the small intestine: which is the most effective algorithm in a rat model?

BACKGROUND: Mesenteric ischemia is a serious clinical condition requiring immediate surgical intervention. The unavoidable ischemic-reperfusion (IR) injury may be ameliorated using the appropriate postconditioning protocol. The aim of the present study was to investigate the optimal postconditioning algorithm in a rat model of intestinal ischemic-reperfusion injury. MATERIALS AND METHODS: Male Wistar rats were randomized into five groups (n = 10), one sham-operated, one IR, and three postconditioned groups, each with different protocols. The animals were subjected to 60 min of mesenteric ischemia, followed by 60 min of reperfusion. Postconditioning was applied at the onset of reperfusion using three different algorithms. Arterial pressure and mucosal microcirculation were monitored throughout the experiment. Mesenteric pH was determined at the early phase of reperfusion. Blood and tissue samples were taken at the end of reperfusion for histologic evaluation, serum lactate dehydrogenase, serum creatine kinase, serum tumor necrosis factor-α, serum interleukin-6, detailed mucosal antioxidant, and scavenger capacity assays. RESULTS: The shorter and intermediate length cycles of postconditioning enhanced mucosal microcirculation and redox state and significantly delayed the normalization of mesenteric pH. Furthermore, milder histopathologic lesions and lower concentrations of serum necroenzymes and proinflammatory cytokines were detected compared with the IR group. The protective effect of postconditioning using longer cycles could only be seen in a tendentious manner. CONCLUSIONS: In a rat model of intestinal ischemia-reperfusion, the shorter and intermediate length cycles of postconditioning proved to be more effective than the use of longer cycles.

Therapeutic option for managing lung injury induced by infrarenal aortic cross-clamping.

BACKGROUND: Operations on the infrarenal aorta can cause ischemic-reperfusion (IR) injury in local tissues, which could result in remote organ (e.g., lung) damage. Treatment of such injuries remains an unresolved problem. OBJECTIVES: Our aim was to reduce remote lung damage after lower limb IR by means of postconditioning. MATERIALS AND METHODS: Male Wistar rats were divided into three groups: Sham-operated, IR, and Postconditioned (PostC). In the latter two groups rats underwent 180 min of exclusion of the infrarenal aorta. The reperfusion time was 4 h. Serum-free radical levels, tumor necrosis factor-α and interleukin-6 concentrations, histologic changes in the lung, wet/dry-ratio, myeloperoxidase activity, heat shock protein 72 level and blood gas changes were investigated. RESULTS: Postconditioning reduced histological damage in the lung (P < 0.05). Free radical levels and tumor necrosis factor-α concentrations were significantly lower in the PostC group than in the IR group (P < 0.05 and P < 0.01, respectively). Interleukin-6 concentrations did not significantly differ in the PostC group. Compared with the IR group, lung myeloperoxidase activity was lower in the PostC group. Decreased pulmonary heat shock protein 72 level was observed in the PostC group compared with the IR group and the wet/dry-ratio was also significantly lower in the PostC group (P < 0.05). A noticeably higher arterial pO2 level was manifest in the PostC group after 2 and 4 h of reperfusion (P < 0.05). CONCLUSIONS: Postconditioning reduced lung damage under experimental conditions, in the early period of reperfusion after lower limb IR injury.

[Postconditioning can reduce long-term lung injury after lower limb ischemia-reperfusion]. / Alsó végtagi ischaemiás-reperfusiós károsodás hosszú távú tüdoszövodményeinek megelozése posztkondicionálással.

INTRODUCTION: Operation on the infrarenal aorta could cause ischemic-reperfusion (IR) injury in local tissues and remote organs (e.g. the lung). OBJECTIVES: Our aim was to reduce long-term lung damage, after lower limb IR with postconditioning. MATERIALS AND METHODS: Male Wistar rats underwent 180 minutes of bilateral lower limb ischemia. Animals were divided into three groups: Sham-operated, IR, Postconditioned (PostC) and further to two subgroups according to reperfusion time: 24 h and 72 h. Serum free radical and IL-6 levels, histological changes, Wet/Dry (W/D) ratio, tissue myeloperoxidase (MPO) activity and Hsp72 levels were investigated. RESULTS: Postconditioning can reduce histological changes in the lung. Free radical levels are significantly lower in PostC groups than in IR groups (42.9 ± 8.0 vs. 6.4 ± 3.4; 27.3 ± 4.4 vs. 8.3 ± 4.0 RLU%; p < 0.05). IL-6 level (238.4 ± 31.1 vs. 209.1 ± 18.8; 190.0 ± 8.8 vs. 187.0 ± 14.9 pg/ml) and Hsp72 expression did not show any significant difference. Compared to the IR group, lung MPO activity did not change in the PostC groups. W/D ratio in PostC groups is significantly lower at all measured time-points (68% vs. 65%; 72% vs. 68%; p < 0.05). CONCLUSION: Postconditioning may reduce long-term damages of the lung after lower limb ischemic-reperfusion injury.