Dragan Cvetković

Unusual Forms of Ruptured Abdominal Aortic Aneurysms

Over 95% of abdominal aortic aneurysms (AAAs) rupture into the retroperitoneal space. Rare types of AAA ruptures comprise ruptures into the inferior vena cava with aortocaval fistula formation (ACF), ruptures into the duodenum with formation of a primary aortoduodenal fistula (ADF), and chronic contained ruptures (CCRs). This article presents a study of 41 cases with unusual forms of ruptured AAA of a series of 506 patients with AAA rupture treated within a 14-year period. There were 11 cases of CCR, 5 cases with ADF, and 25 cases with ACF. The correct preoperative diagnosis was established in 6 (of 11) cases of CCR, in 2 (of 5) cases of primary ADF, and in 13 (of 25) cases of ACF. AAA replacement was performed in 8 cases using a tube graft, whereas a bifurcated graft was used in 31 patients because of the distant extent of the atherosclerotic/aneurysmatic lesions engaging iliac arteries. Two patients had an axillobifemoral bypass. The overall 30-day mortality rate was 19% (8 of 41), with subgroup mortality rates of 0 (CCR), 60% (ADF), and 20% (ACF). Diagnosis and treatment are simplest in cases of CCR and the most complicated in cases of ADF.

False Anastomotic Aneurysms

This retrospective study covers the period from 1991 to 2002, during which 3,623 patients were operated on because of aneurysmal or occlusive disease of aortoiliac and femoropopliteal segments. Among them, 87 patients (2.4%) developed a false anastomotic aneurysm in the 12-year follow-up period and were treated operatively. Most frequently, in 53 patients (6.9%), a false anastomotic aneurysm developed after aortobifemoral bypass performed owing to aortoiliac occlusive disease. The cause of false anastomotic aneurysm was infection in 21 cases (24.7%); resection and revascularization were performed with a Dacron graft in 46 cases (52.9%), with a polytetrafluoroethylene graft in 10 cases (11.5%), and with the great saphenous vein in 16 cases (18.4%). Homograft implantation in 4 patients (4.6%) or extra-anatomic bypasses in 11 cases (12.6%) were performed when graft infection was suspected. Of 87 patients who underwent surgery, 74 (85.5%) had good early results without infection, reintervention, limb loss, and mortality. The presence of infection as a cause of false anastomotic aneurysm and comorbidity increased the mortality rate significantly after the reoperation, whereas the type of graft used in treatment had no influence on early results.

Web-based laboratory for collaborative and concurrent CAD designing, assembling, and practical exercising on distance

Original scientific paper Collaborative CAD of distant modelling is a today’s necessity for realization in a timely manner. This need arises even within educational institutions, where investments in the development of technologies to support collaborative distance learning are still trivial. Most CAD programs used in engineering have modules for collaboration. However, these solutions are expensive, especially for educational institutions that have a large number of students. The mentioned modules generally work within a specific CAD platform and support import and export of a limited number of CAD formats. In this paper, we present an open-source solution that overcomes these problems. It implements practical work at a distance by combining most commonly used CAD platforms in engineering. In this paper, we describe how to use virtual laboratory for rapid designing through execution of practical exercises. The architecture of the proposed solution, the modelling of the laboratory and methods for creating its functions are described. Also, given is a tangible example of collaborative aircraft assembly between distant students, with parts modelled in different CAD packages, and the usability of labs presented through prototype builds on 3D printer and the final test in the wind tunnel. Qualitative and quantitative evaluations were conducted. Conclusions set the direction of the future development using various technologies for building virtual assembly laboratory.

Predicting the movement of robotic platforms based on memory scanning test

This paper presents an overview of a possible new concept that can define the movement of robotic platforms on unstructured terrain in an undefined environment based on the stored sample taken from the scanning IR sensors. The proposed solutions are based on many years of work and research that are conducted at the Faculty of Information Technology, the University Singidunum. The final work presented here was supported by the Serbian Ministry of Education and Science (project III44006).

Model of image decomposition presentation with a quadtree

The paper analyzes the procedure of image decomposition with a quadtree. The main goal of the paper is to present one of the models of image decomposition with a quadtree implemented within the program package Matlab 7.0. A precondition for designing such a model is the durability of the programs that represent various image characteristics and enable particular image processing and transformation. The paper consists of three main chapters: “Image compression and decomposition”, “Decomposition image model with a quadtree” and “Results and analyses of image decomposition with a quadtree”.