Search

The stochastic rupture risk assessment of an abdominal aortic aneurysm (AAA) critically depends on sufficient data set size that would allow for the proper distribution estimate. However, in most published cases, the data sets comprise no more than 100 samples, which is deemed insufficient to describe the tails of AAA wall thickness distribution correctly. In this study, we propose a stochastic Bayesian model to merge thickness data from various groups. The thickness data adapted from the literature were supplemented by additional data from 81 patients. The wall thickness was measured at two different contact pressures for 34 cases, which allowed us to estimate the radial stiffness. Herein, the proposed stochastic model is formulated to predict the undeformed wall thickness. Furthermore, the model is able to handle data published solely as summary statistics. After accounting for the different contact pressures, the differences in the medians reported by individual groups decreased by 45%. Combined data can be fitted with a lognormal distribution with parameters μ = 0.85 and σ = 0.32 which can be further used in stochastic analyses., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kracík et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The biomechanical rupture risk assessment (BRRA) of abdominal aortic aneurysms (AAA) has higher sensitivity than maximal diameter criterion (D SEX ) but its estimation is time-consuming and relies on an uncertain estimation of wall thickness. The aim of this study is to test tension-based criterion in the BRRA of AAA which removes the necessity of wall thickness measurement and should be faster. For that, we retrospectively analyzed 99 patients with intact AAA (25 females). Nineteen of them experienced a rupture later. BRRA was performed with wall tension PRRI T as a primary criterion. The ability of criterion to separate intact and ruptured AAAs at 1,3,6,9 and 12 months was estimated. Next, the receiver operating characteristics and the percentage of true negative cases for a different time to an outcome were estimated. Finally, the computational time was recorded. The results were compared to stress-based criterion PRRI and D SEX which served as a reference. All three criterions were able to discriminate between intact and ruptured AAAs up to 9 months (p < 0.05) while none of them could do for a 12 month prediction. PRRI T exhibited a significantly higher percentage of true negatives for 12 and 9 month predictions (45 % and 20 % respectively) and similar to other criteria for other prediction times. The mean computational time for estimating PRRI T was 19 h per patient compared to 67 h for PRRI. The tension- based BRRA of AAA leads to better outcomes for a 9 and 12 month prediction while the computational time drops by more than 70 % compared to PRRI., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: Acute intestinal ischemia is a severe complication of abdominal aortic surgery that is difficult to diagnose early and therefore to treat adequately and timely. In this study the perioperative kinetics of d-lactate and ischemia-modified albumin (IMA) are described and the predictive value of these markers for the early diagnosis of acute intestinal ischemia is assessed., Design & Methods: This non-randomised, single-centre cohort study enrolled 50 patients with abdominal aortic aneurysm (AAA) and 30 patients with aortoiliac occlusive disease (AOID). Serum d-lactate and IMA were assessed pre-, intra-, and postoperatively at eight defined time points., Results: The highest serum d-lactate was at 6 h after complete declamping of the vascular graft. The highest predictive power of d-lactate was at 3 h after complete declamping (AUC 0.857). IMA was found to be higher in the AAA group in ischemic patients 10 min after complete declamping than in the AOID group. The highest predictive values of IMA were at 1 h after aortic cross-clamping (AUC 0.758) and 3 and 6 h after complete declamping (0.745 and 0.721, respectively). Moreover, the multivariate model with both markers at 3 h after complete declamping improved the detection of intestinal ischemia (AUC 0.894)., Conclusions: Serum levels of IMA and d-lactate seem to be influential predictive markers for postoperative intestinal ischemia, especially after 3 h from complete declamping of vascular reconstruction., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

Introduction: Abdominal aortic aneurysm (AAA) is a relatively frequent and serious condition in vascular surgery. The diagnostic and indication process and its treatment are driven by the guidelines which dictate an intervention when the maximum AAA diameter is more than 55 mm. Nevertheless, this approach is not fully sufficient in all AAA cases and thus we have been seeking to develop a modern diagnostic tool using computer modeling and vascular wall stress analysis., Methods: The project has been ongoing in cooperation with engineers from VUT Brno (Brno University of Technology) and V&#352;B Ostrava (Technical University of Ostrava) for ten years. The design of the analytical tool was created during the first, experimental period of the project; this tool is able to assess vascular wall stress from regular CT scans using the finite element method. This primary model was gradually altered and its precision was increased considerably in the course of the years using data from mechanical and histological tests of AAA wall specimens harvested during open repairs. Additionally, other patient specific data are included in the analysis such as blood pressure, gender and material characteristics., Results: The effectiveness of the method was evaluated in a pseudo-prospective study, showing clear superiority of the vascular wall stress analysis over the maximum diameter approach. The method was used in clinical practice for the first time during restrictions due to the COVID-19 pandemic; based on the analysis we were able to assess which AAA cases can be postponed and which had a high risk of rupture and an intervention was required despite the restrictions. The method achieved 100% sensitivity, and its specificity was also much better compared to the maximum diameter approach., Conclusion: The vascular wall stress analysis of AAA seems to be much more precise than the classic indication approach based only on the maximum diameter, and it can be used to determine the therapy based on patient specific parameters.

Background: Postoperative intestinal ischemia is a severe complication in abdominal aortic surgery. Early diagnosis is needed for adequate and timely treatment. We studied the postoperative kinetics of l-lactate in vascular patients to assess its value as a marker for early postoperative intestinal ischemia detection., Material and Methods: We performed a prospective non-randomized single-center observational cohort study in eighty elective patients, fifty operated on for abdominal aortic aneurysm (AAA) and thirty for aortoiliac occlusive disease (AIOD). Serum l-lactate was measured preoperatively, intraoperatively, and postoperatively at defined timepoints up to postoperative day 7. Intestinal ischemia was detected using MRI enterocolography. We have used univariate logistic regression and receiver operating characteristics curves for the evaluation of marker accuracy., Results: We recorded 6 cases of postoperative intestinal ischemia (7.5%), five non-transmural and one transmural. Two patients died because of this complication (mortality 33%). The comparison of AAA and AIOD cohorts showed a significant difference in l-lactate levels at one intraoperative timepoint, which was attributable to procedure differences. The only preoperative factor associated with higher l-lactate levels at some timepoints was chronic kidney disease. Patients suffering postoperative intestinal ischemia had elevated serum l-lactate levels at multiple timepoints. The most accurate timepoint for diagnosis was 24 h after the declamping of the vascular reconstruction (DC24H), the second was 10 min after declamping. Sensitivity, specificity, positive and negative predictive values at timepoint DC24H were 100%, 82%, 32%, and 100%, respectively., Conclusion: Serum l-lactate levels might help in the early detection of postoperative intestinal ischemia after aortic surgery if proper timepoints are used. Cutoff values need to be established in large-scale prospective studies., (Copyright © 2022 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.)

Background and Objective: Estimating patient specific annual risk of rupture of abdominal aortic aneurysm (AAA) is currently based only on population. More accurate knowledge based on patient specific data would allow surgical treatment of only those AAAs with significant risk of rupture. This would be beneficial for both patients and health care system., Methods: A methodology for estimating annual risk of rupture (EARR) of abdominal aortic aneurysms (AAA) that utilizes Bayesian statistics, mechanics and patient-specific blood pressure monitoring data is proposed. EARR estimation takes into consideration, peak wall stress in AAA computed by patient-specific finite element modeling, the probability distributions of wall thickness, wall strength, systolic blood pressure and the period of time that the patient is known to have already survived with the intact AAA. Initial testing of proposed approach was performed on fifteen patients with intact AAA (mean maximal diameter 51mm±8mm). They were equipped with a pressure holter and their blood pressure was recorded over 24 hours. Then, we calculated EARR values for four possible scenarios - without considering any days of survival prior identification of AAA at computed tomography scans (EARR&#95;0), considering past survival of 30 (EARR&#95;30), 90 (EARR&#95;90) and 180 days (EARR&#95;180). Finally, effect of patient-specific blood pressure variability was analyzed., Results: Consideration of past survival does indeed significantly improve predictions of future risk: EARR&#95;30 (1.04%± 0.87%), EARR&#95;90 (0.67%± 0.56%) and EARR&#95;180 (0.47%± 0.39%) which are unrealistically high otherwise (EARR&#95;0 5.02%± 5.24%). Finally, EARR values were observed to vary by an order as a consequence of blood pressure variability and by factor of two as a consequence of neglected growth., Conclusions: Methodology for computing annual risk of rupture of AAA was developed for the first time. Sensitivity analyses showed respecting patient specific blood pressure is important factor and should be included in the AAA rupture risk assessment. Obtained EARR values were generally low and in good agreement with confirmed survival time of investigated patients so proposed method should be further clinically validated., (Copyright © 2020. Published by Elsevier B.V.)

Introduction: Biomechanical rupture risk assessment of abdominal aortic aneurysm (AAA) requires information about failure properties of aneurysmal tissue. There are large differences between reported values. Among others, studies vary in using either axially or circumferentially oriented samples. This study investigates the effect of sample orientation on failure properties., Methods: Aneurysmal tissues from 45 patients (11 females) were harvested during open AAA repair, cut into uniaxial samples (90) and tested mechanically within 3 h. If possible, the samples were cut in both axial (49 samples) and circumferential (41 samples) directions. Wall thickness, First Piola-Kirchhoff strength P ult and ultimate tension T ult were recorded. Influence of sample orientation and other clinical parameters were investigated using non parametric tests., Results: Medians of P ult (values 1100 kPa for circumferential vs. 715 kPa for axial direction, p < 10 -4 ) and T ult (17.4 N/cm in circumferential vs. 11.2 N/cm in axial direction, p < 10 -4 ) were significantly higher in circumferential direction. For paired data, the median of difference was 411 kPa (p < 10 -3 ) in P ult and 7.4 N/cm (p < 10 -4 ) in T ult in favor of circumferential direction., Conclusions: In this first study of anisotropy in AAA wall failure properties using paired comparisons, the strength in circumferential orientation was found to be higher than in axial orientation., (Copyright © 2020. Published by Elsevier Ltd.)

Objective: Several studies of biomechanical rupture risk assessment (BRRA) showed its advantage over the diameter criterion in rupture risk assessment of abdominal aortic aneurysm (AAA). However, BRRA studies have not investigated the predictability of biomechanical risk indices at different time points ahead of rupture, nor have they been performed blinded for biomechanical analysts. The objective of this study was to test the predictability of the BRRA method against diameter-based risk indices in a quasi-prospective patient cohort study., Methods: In total, 12 women and 31 men with intact AAAs at baseline have been selected retrospectively at two medical centers. Within 56 months, 19 cases ruptured, whereas 24 cases remained intact within 2 to 56 months. This outcome was kept confidential until all biomechanical activities in this study were finished. The biomechanical AAA rupture risk was calculated at baseline using high-fidelity and low-fidelity finite element method models. The capability of biomechanics-based and diameter-based risk indices to predict the known outcomes at 1 month, 3 months, 6 months, 9 months, and 12 months after baseline was validated. Besides common cohort statistics, the area under the curve (AUC) of receiver operating characteristic curves has been used to grade the different rupture risk indices., Results: Up to 9 months ahead of rupture, the receiver operating characteristic analysis of biomechanics-based risk indices showed a higher AUC than diameter-based indices. Six months ahead of rupture, the largest difference was observed with an AUC of 0.878 for the high-fidelity biomechanical risk index, 0.859 for the low-fidelity biomechanical risk index, 0.789 for the diameter, and 0.821 for the sex-adjusted diameter. In predictions beyond 9 months, none of the risk indices proved to be superior., Conclusions: High-fidelity biomechanical modeling improves the predictability of AAA rupture. Asymptomatic AAA patients with high biomechanical AAA rupture risk indices have an increased risk of rupture. Integrating biomechanics-based diagnostic indices may significantly decrease the false-positive rate in AAA treatment., Clinical Relevance: Rupture of abdominal aortic aneurysm (AAA) is the tenth leading cause of death in men older than 60 years; however, the currently used maximal diameter criterion has a high false-positive rate. In this study, we have compared this criterion with biomechanical rupture risk assessment on the unique data set of 43 asymptomatic AAAs, of which 19 ruptured later. Moreover, the AAA outcome was blinded to the operator for the first time. Our data demonstrated that the biomechanical rupture risk assessment is superior to maximal diameter in predicting AAA rupture up to 9 months ahead and significantly decreases the false-positive rate., (Copyright © 2019 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.)

Background: Abdominal aortic aneurysm (AAA) includes a variety of morphologies with changing properties. Growth rate is one of the most important factors directly linked to the risk of rupture. Intraluminal thrombus (ILT) covering aortic wall is found in the majority of AAAs. Yet, its role in biomechanical processes in AAA remains unclear. From one point of view ILT can serve as protective factor in reducing wall stress of AAA and thus slow down the growth. Modern concept of multilayered ILT proved active inflammatory processes inside, that can significantly affect the quality of the wall and thus lead to a higher growth rate and higher risk of rupture. The goal of this study was to analyze the effect of ILT on growth rate of AAA and support one of these theories., Methods: Retrospective study of computed tomography angiography scans of AAA of 26 patients was performed. Forty pairs of consecutive scans have been analyzed. Periods between two scans varied. Maximal infrarenal diameter of AAA and size of ILT were measured. AAAs were split into 4 groups according to their initial diameter. Growth rate was calculated for each AAA and linked to the relative size of ILT. These values were statistically evaluated., Results: Negative correlation between relative size of ILT and growth rate was found (P=0.042062). This significant result proved that thicker thrombus slowed down the growth of AAA and vice versa, smaller relative size of ILT was linked to higher growth rate., Conclusions: This finding shows importance of ILT as one of the key factors influencing biomechanical processes inside an AAA. Results of this study may contribute to future researches of this topic.

Purpose: There is no standard for measuring maximal diameter (Dmax) of abdominal aortic aneurysm (AAA) from computer tomography (CT) images although differences between Dmax evaluated from transversal (axialDmax) or orthogonal (orthoDmax) planes can be large especially for angulated AAAs. Therefore we investigated their correlations with alternative rupture risk indicators as peak wall stress (PWS) and peak wall rupture risk (PWRR) to decide which Dmax is more relevant in AAA rupture risk assessment., Material and Methods: The Dmax values were measured by a trained radiologist from 70 collected CT scans, and the corresponding PWS and PWRR were evaluated using Finite Element Analysis (FEA). The cohort was ordered according to the difference between axialDmax and orthoDmax (D a-o ) quantifying the aneurysm angulation, and Spearman's correlation coefficients between PWS/PWRR - orthoDmax/axialDmax were calculated., Results: The calculated correlations PWS/PWRR vs. orthoDmax were substantially higher for angulated AAAs (with D a-o ≥3mm). Under this limit, the correlations were almost the same for both Dmax values. Analysis of AAAs divided into two groups of angulated (n=38) and straight (n=32) cases revealed that both groups are similar in all parameters (orthoDmax, PWS, PWRR) with the exception of axialDmax (p=0.024)., Conclusions: It was confirmed that orthoDmax is better correlated with the alternative rupture risk predictors PWS and PWRR for angulated AAAs (D A-O ≥3mm) while there is no difference between orthoDmax and axialDmax for straight AAAs (D A-O <3mm). As angulated AAAs represent a significant portion of cases it can be recommended to use orthoDmax as the only Dmax parameter for AAA rupture risk assessment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Infection represents a less frequent cause for the development of an abdominal aortic aneurysm. The diagnosis is associated with a high risk of rapir progression and rupture., Case Reports: Case 1 is a female operated on urgently for a ruptured mycotic aneurysm of the abdominal aorta. After resection of the aneurysm, we performed in situ replacement using a rifampicin-soaked vascular prosthesis. In case 2, an asymptomatic aneurysm of the right iliac artery was treated by endovascular implantation of a stent-graft. Both patients were treated with antibiotics concurrently and are still alive., Discussion: The discussion deals with the up-to-date treatment modalities for mycotic aneurysms in the aorto-iliac region. The indication criteria must be adjusted individually., Conclusion: The prognosis of patients with a mycotic aneurysm depends particularly on an early diagnosis., (Georg Thieme Verlag KG Stuttgart · New York.)

Arterial physiology relies on a delicate three-dimensional (3D) organization of cells and extracellular matrix, which is remarkably altered by vascular diseases like abdominal aortic aneurysms (AAA). The ability to explore the micro-histology of the aorta wall is important in the study of vascular pathologies and in the development of vascular constitutive models, i.e., mathematical descriptions of biomechanical properties of the wall. The present study reports and validates a fast image processing sequence capable of quantifying collagen fiber organization from histological stains. Powering and re-normalizing the histogram of the classical fast Fourier transformation (FFT) is a key step in the proposed analysis sequence. This modification introduces a powering parameter w, which was calibrated to best fit the reference data obtained using classical FFT and polarized light microscopy (PLM) of stained histological slices of AAA wall samples. The values of w = 3 and 7 give the best correlation (Pearson's correlation coefficient larger than 0.7, R 2 about 0.7) with the classical FFT approach and PLM measurements. A fast and operator independent method to identify collagen organization in the arterial wall was developed and validated. This overcomes severe limitations of currently applied methods like PLM to identify collagen organization in the arterial wall.

Background: Results of biomechanical simulation of the abdominal aortic aneurysm (AAA) depend on the constitutive description of the wall. Based on in vitro and in vivo experimental data several constitutive models for the AAA wall have been proposed in the literature. Those models differ strongly from each other and their impact on the computed stress in biomechanical simulation is not clearly understood., Methods: Finite element (FE) models of AAAs from 7 patients who underwent elective surgical repair were used to compute wall stresses. AAA geometry was reconstructed from CT angiography (CT-A) data and patient-specific (PS) constitutive descriptions of the wall were derived from planar biaxial testing of anterior wall tissue samples. In total 28 FE models were used, where the wall was described by either patient-specific or previously reported study-average properties. This data was derived from either uniaxial or biaxial in vitro testing. Computed wall stress fields were compared on node-by-node basis., Results: Different constitutive models for the AAA wall cause significantly different predictions of wall stress. While study-average data from biaxial testing gives globally the same stress field as the patient-specific wall properties, the material model based on uniaxial test data overestimates the wall stress on average by 30 kPa or about 67% of the mean stress. A quasi-linear description based on the in vivo measured distensibility of the AAA wall leads to a completely altered stress field and overestimates the wall stress by about 75 kPa or about 167% of the mean stress., Conclusion: The present study demonstrated that the constitutive description of the wall is crucial for AAA wall stress prediction. Consequently, results obtained using different models should not be mutually compared unless different stress gradients across the wall are not taken into account. Highly nonlinear material models should be preferred when the response of AAA to increased blood pressure is investigated, while the quasi-linear model with high initial stiffness produces negligible stress gradients across the wall and thus, it is more appropriate when response to mean blood pressure is calculated., (Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.)

Wall stress analysis of abdominal aortic aneurysm (AAA) is a promising method of identifying AAAs at high risk of rupture. However, neglecting residual strains (RS) in the load-free configuration of patient-specific finite element analysis models is a sever limitation that strongly affects the computed wall stresses. Although several methods for including RS have been proposed, they cannot be directly applied to patient-specific AAA simulations. RS in the AAA wall are predicted through volumetric tissue growth that aims at satisfying the homogeneous stress hypothesis at mean arterial pressure load. Tissue growth is interpolated linearly across the wall thickness and aneurysm tissues are described by isotropic constitutive formulations. The total deformation is multiplicatively split into elastic and growth contributions, and a staggered schema is used to solve the field variables. The algorithm is validated qualitatively at a cylindrical artery model and then applied to patient-specific AAAs (n = 5). The induced RS state is fully three-dimensional and in qualitative agreement with experimental observations, i.e., wall strips that were excised from the load-free wall showed stress-releasing-deformations that are typically seen in laboratory experiments. Compared to RS-free simulations, the proposed algorithm reduced the von Mises stress gradient across the wall by a tenfold. Accounting for RS leads to homogenized wall stresses, which apart from reducing the peak wall stress (PWS) also shifted its location in some cases. The present study demonstrated that the homogeneous stress hypothesis can be effectively used to predict RS in the load-free configuration of the vascular wall. The proposed algorithm leads to a fast and robust prediction of RS, which is fully capable for a patient-specific AAA rupture risk assessment. Neglecting RS leads to non-realistic wall stress values that severely overestimate the PWS.

Introduction: Using retrospective analysis, we sought to investigate the incidence, risk factors and therapeutic outcomes of ischemic colitis in patients after surgical and endovascular repair of abdominal aortic aneurysms (AAA)., Material and Methods: The complete inpatient and outpatient medical records of all patients undergoing surgical or endovascular AAA repair in our Department from January 2005 to December 2009 were retrospectively reviewed. We selected all patients who had developed an acute or chronic form of postoperative large or small bowel ischemia. We carried out data analysis and focused on determining the incidence and risk factors of this complication and the outcomes of its treatment., Results: Two hundred and seven AAA repairs were performed in the 2nd Department of Surgery of St. Anne's University Hospital in Brno and the Faculty of Medicine of Masaryk University in Brno during the studied period. This number includes endovascular AAA repairs (13 patients; 6.3%) as well as one robot-assisted operation, and also the whole clinical spectrum of AAA manifestations, from non-symptomatic forms to ruptured aneurysm forms. The rest of the patients underwent open operation. Bowel ischemia developed in a total of 11 patients (5.3 %), who all underwent open AAA repair. Six of these patients presented with non-ruptured AAA and the remaining 5 with ruptured AAA. In 3 patients, bowel ischemia was diagnosed with a delay of several months from the original revascularization operation in the clinical form of postischemic stricture of the large bowel (2 patients) or postischemic colitis (1 patient). 8 patients were diagnosed with acute ischemic colitis affecting an isolated segment of the small bowel in one patient, extended segments of the large bowel (descending colon + sigmoid colon + rectum) in 2 patients, and typically the descending and sigmoid colon in 5 patients. None of the three patients with late manifestation of ischemic colitis died. Of the 8 patients with acute presentation, resection of the ischemic bowel +/- the rectum was performed in 6 patients. 3 of them died and 3 survived the operation and have been followed up in our outpatient department. 2 patients with acute manifestation did not undergo bowel resection. Both of them died. The overall mortality of all patients with ischemic colitis was 45.5% (5 patients out of 11 died) in our study. When considering only patients suffering from the acute form of ischemic colitis, the mortality rate in our studied cohort amounts to 62.5% (5 patients out of 8 died)., Conclusion: Bowel ischemia after AAA repair remains to be a serious complication. Besides the acute form of ischemic colitis, its possible late clinical manifestation in the form of postischemic stricture of the large bowel or postischemic large bowel colitis must also be kept in mind when following up patients. The analysis of our patient's data shows that conditions requiring the use of vasopressors and an increased need of transfusions (more than 7 units of packed red blood cells) intraoperatively represent important predictors of colon ischemia after AAA repair.

Introduction: Replanting the inferior mesentery artery during infrarenal aortic aneurysm repair is a measure which might prevent development of colon ischemia under certain circumstances. These circumstances and patients who would benefit from this procedure are not well defined., Case Report: 64-year old man underwent an elective operation on infrarenal AAA at our institution in December 2009. From preoperative CT angiography we knew about the accessory right renal artery branching directly from AAA and bilateral occlusion of hypogastric arteries. We performed open resection of AAA with implantation of a bifurcated graft. Proximal anastomosis was situated below renal arteries, distal anastomoses were bilaterally constructed on external illiac arteries. The accessory right renal artery was anastomosed into the right limb of the graft and IMA was replanted into the body of the graft. Postoperative recovery of the patient was uneventful. His follow-ups 3 and 6 months after the operation have been showing good clinical state of the patient, absence of abdominal complaints and normal levels of urea and creatinine. CT angiography which was performed 3 months after the operation discovered an occlusion of the reimplanted IMA, but patent replanted accessory right renal artery., Discussion: Assessment of collateral circulation of large intestine during infrarenal AAA repair is influenced by many preoperative and intraoperative factors. Most surgeons judge the adequacy of the collateral circulation by IMA backbleeding combined with inspection of sigmoid colon after restoring aortic flow. There have been numerous attempts to replace this subjective approach with more objective methods like intraoperative colon mucosal saturation measurement, laser Doppler flowmetry, IMA stump pressures, photophletyzmographic technique. Even though these methods describe conditions when a collateral circulation of rectosigmoid is inadequate after IMA ligature, they are unable to fully eliminate the occurrence of colon ischemia because of its multifactorial nature. Solving the problem of collateral circulation of the large intestine represents only a part of the obstacle presented by colon ischemia after infrarenal AAA repair., Conclusion: IMA replantation during infrarenal AAA repair does not fully prevent an occurance of colon ischemia. On the other side, this moneuver does not increase perioperative morbidity, nor prolongs an operation significantly. Our policy is to replant IMA whenever we thing the circulation of large intestine is under threat or in borderline situations.

Mycotic aneurysm of the abdominal aorta is a rare, but potentially lethal disorder because of the risk of rupture. It presents a permanent problem in vascular surgery. Despite recent advances in endovascular procedures, one of the available surgical interventions generally remains the method of choice. The authors present the case of a patient with a ruptured mycotic aneurysm of the abdominal aorta who urgently underwent aorto-biiliac reconstruction by an autologous superficial femoral vein graft. The patient's post-operative condition with the absence of complications is in agreement with the good results achieved with this technique by surgeons abroad, and gives support to the notion that this approach is superior to other surgical treatments of mycotic aneurysms.

The authors present the results of a retrospective study concerning 96 patients with an abdominal aortic aneurysm rupture who underwent surgery in the 2nd Department of Surgery in Brno in the time period from 1989 to 1999. In 30 cases (31.2%) there was an isolated retroperitoneal rupture, 66 patients (68.8%) also had haemoperitoneum. The mean age of the patients was 74 years and the male/female ratio was 76 (79.2%): 20 (20.8%). Twelve patients (40%) did not survive the retroperitoneal rupture, and 34 patients (51.5%) did not survive the intraabdominal rupture. Total mortality in the study group was 47.9%. The type of the rupture and the size of the haematoma that is in correlation with the time of diagnosis and operation, are among the most decisive prognostic factors. Patients with a small haematoma show higher survival rates. In large retroperitoneal haematomas accompanied by a haemorrhagic shock, the mortality was about 40% in the presented study group, in intraabdominal ruptures the mortality rate increases to values over 50%. The results are in accordance with foreign literature data, and the authors agree with the opinion that haemodynamically unstable patients with suspected abdominal aortic aneurysm rupture should be, after necessary preparations, urgently operated without complementary examinations.