Browsing by Author "Koncar, I. (19337386500)"

Objectives: The study aimed to identify differences and compare anatomical and biomechanical features between elective and ruptured abdominal aortic aneurysms (AAAs). Methods: Data (clinical, anatomical, and biomechanical) of 98 patients with AAA, 75 (76.53%) asymptomatic (Group aAAA) and 23 (23.46%) ruptured AAA (Group rAAA), were prospectively collected and analyzed. Anatomical, morphological, and biomechanical imaging markers like peak wall stress (PWS) and rupture risk equivalent diameter (RRED), comorbid conditions, and demographics were compared between the groups. Biomechanical features were assessed by analysis of Digital Imaging and Communication in Medicine images by A4clinics (Vascops), and anatomical features were assessed by 3Surgery (Trimensio). Binary and multiple logistic regression analysis were used and adjusted for confounders. Accuracy was assessed using receiving operative characteristic (ROC) curve analysis. Results: In a multivariable model, including gender and age as confounder variables, maximal aneurysm diameter [MAD, odds ratio (OR) = 1.063], relative intraluminal thrombus (rILT, OR = 1.039), and total aneurysm volume (TAV, OR = 1.006) continued to be significant predictors of AAA rupture with PWS (OR = 1.010) and RRED (OR = 1.031). Area under the ROC curve values and correct classification (cc) for the same parameters and the model that combines MAD, TAV, and rILT were measured: MAD (0.790, cc = 75%), PWS (0.713, cc = 73%), RRED (0.717, cc = 55%), TAV (0.756, cc = 79%), rILT (0.656, cc = 60%), and MAD + TAV + rILT (0.797, cc = 82%). Conclusion: Based on our results, in addition to MAD, other important predictors of rupture that might be used during aneurysm surveillance are TAV and rILT. Biomechanical parameters (PWS, RRED) as valuable predictors should be assessed in prospective clinical trials. Similar studies on AAA smaller than 55 mm in diameter, even difficult to organize, would be of even greater clinical value. 2023 Koncar, Nikolic, Milosevic, Bogavac-Stanojevic, Ilic, Dragas, Sladojevic, Markovic, Vujcic, Filipovic and Davidovic.

The aim of this study was to demonstrate how fluid dynamic parameters are affected by aortic geometry and flow condition in two cases. Case A included blood flow analysis in aortic system with abdominal aortic aneurysm and left common iliac aneurysm before stent graft placement, while in case B was included stent graft geometry, at the site of the aneurysms. An individual patient-specific geometry and a 3D finite element meshes were reconstructed, based on Computed tomography (CT) scan images. The analysis was performed using the possibilities of computational fluid dynamics. It uses numeric methods and algorithms for the simulation of blood flow by solving the Navier-Stokes equations on computational meshes. The computational simulations of cardiac cycles were performed for average blood properties and blood flow rate. The velocity field, pressure and shear stress, as main fluid dynamics parameters, were visualized and compared for cases A and B. © 2018 S. Djorovic et al.

The aim of this study was to demonstrate how fluid dynamic parameters are affected by aortic geometry and flow condition in two cases. Case A included blood flow analysis in aortic system with abdominal aortic aneurysm and left common iliac aneurysm before stent graft placement, while in case B was included stent graft geometry, at the site of the aneurysms. An individual patient-specific geometry and a 3D finite element meshes were reconstructed, based on Computed tomography (CT) scan images. The analysis was performed using the possibilities of computational fluid dynamics. It uses numeric methods and algorithms for the simulation of blood flow by solving the Navier-Stokes equations on computational meshes. The computational simulations of cardiac cycles were performed for average blood properties and blood flow rate. The velocity field, pressure and shear stress, as main fluid dynamics parameters, were visualized and compared for cases A and B. © 2018 S. Djorovic et al.

Spinal cord ischemia remains the most impressive and colliding complication following open surgical and endovascular aortic procedures. Paraparesis and paraplegia are devastating, having a major invalidating impact on the patient's life. Also for the surgeon and the entire team this dramatic adverse event causes a significant concussion. Surgeons faced this problem in practice in the 1950s when this surgery started being applied. Even A. Carrel in 1910 said, "The main danger of the aortic operation does not come from the heart or from the aorta itself, but from the central nervous system". As the number of these surgeries grew, some were followed by the spinal cord ischemia. Now, in 21st century, problem of spinal cord ischemia still exists. By understanding the reasons of its development we shall be able to find more useful methods for prevention as well as for the treatment. The aim of this article was to search what is behind this dreadful complication, explaining different mechanisms which take part in its development during endovascular and open surgical treatment.

Background: Introduction of novel procedures needs to be planned and modified according to the situation in the society. The first endovascular aortic repair (EVAR) in Serbia was performed in 2004, and this activity was routinely continued in 2007. Aim of the study is to present the problems encountered during the introduction and development of endovascular program in Serbia, and to report the early experience and mid-term results of the two main Serbian vascular centers. Methods: From March 2007 to November 2010, 1650 patients were operated due to abdominal aortic aneurysm (AAA) in the two main vascular centers in the capital of Serbia. Out of them 87 (5.27%) were treated by EVAR and are included in this Serbian bi-centric study that analyze results as well as developing process. Results: Early mortality rate was 2/87 (2.29%). In the early postoperative time and after mid-term follow-up of 17.9 months (range 2-40 months) there was no aneurysm-related death. All patients with unplanned iliac conduit procedure suffered postoperative complications and dyed. Primary technical success and assisted primary technical success were recorded in 81 (93.1%) and 86 (98.85%) patients, respectively. Initial, assisted initial, short term and mid-term clinical success were recorded in 83 (95%), 84 (96.55%), 84 (96.55%) and 81 (93.10%) patients, respectively. Conclusions: Steep learning curve is a consequence of measured and planned introduction of new procedure only in a high volume centers with previous significant experience in treatment of all vascular pathologies and complications. © Springer-Verlag 2011.

Aim. He aim of this paper was to investigate the incidence of and the indications for conversion to general anesthesia (GA) in a large single-center series of patients undergoing carotid surgery under cervical plexus block (CPB). Methods. With IRB approval we retrospectively analyzed the medical records of all patients who underwent carotid surgery under CPB from November 2007 to October 2010. Cervical plexus was blocked at both the superficial and deep levels. An intraluminal shunt was inserted in patients who demonstrated signs of inadequate cerebral perfusion upon carotid clamping (CC). Propofol was given to patients reporting pain or discomfort throughout the procedure. The primary outcomes were the number and percentage of conversions to GA as well as the indications for this intervention. The secondary outcome was the incidence of partial cervical block failure, defined as the need for supplemental propofol administration for pain relief during surgery. Results. In total, 1464 carotid surgical procedures were performed under CPB in 1305 consecutive patients during the investigated period. Conversion to GA was required in 17 (1.2%) patients. The most common reason for conversion to GA was persisting neurological deterioration upon CC and intraluminal shunt insertion, which was recorded in 8/17 (47.1%) procedures. Other indications to convert were systemic toxicity of local anesthetics, pain, general discomfort and restlessness during surgery, and acute myocardial infarction. Conclusion. Cervical plexus block for carotid surgery is associated with a low rate of conversions to GA. Neurological deterioration upon carotid clamping and local anesthetic toxicity are identified as the most common indications for such intervention.

The role of intraluminal thrombus (ILT) has special attention in these studies. One of the papers showed that asymmetrical intraluminal thrombus deposition (ATDI) has an important role in growth of the AAA. The aim of our study was to assess the asymmetrical thrombus deposition index in ruptured and symptomatic aneurysms. We collected data for 33 aneurysms, 21 (63.63%) asymptomatic and 12 (33.37%) ruptured or symptomatic. Asymmetrical thrombus deposition index (ATDI) was measured by Onis DICOM viewer software. Also, lumen's geometrical centre (LGC) was defined and ATDI was considered positive when the LGC was laid on the posterior section of the sac (meaning dominant anterior ILT distribution) and negative when it was laid on the anterior section (meaning dominant posterior ILT distribution). Maximum aneurysm diameter was 63.4mm in average (50-100mm, SD=12.89); 59.8mm in asymptomatic and 71.16mm in symptomatic or ruptured aneurysm (p=0.012). The absolute value of asymmetric thrombus deposition index was significantly higher in symptomatic/ruptured compared to asymptomatic aneurysm, 0.54 and 0.33, respectively (p=0.041), while there was no difference in frequency of positive or negative thrombus deposition (p=0.261). There was no significant correlation between maximal aneurysm size and absolute value of ATDI (p=0.505). Values of thrombus deposition index are correlating with the development of symptomatology or rupture of the AAA. This variable should be included in much wider mathematical rupture prediction model in order to have more accurate rupture risk assessment. © 2015 IEEE.

The role of intraluminal thrombus (ILT) has special attention in these studies. One of the papers showed that asymmetrical intraluminal thrombus deposition (ATDI) has an important role in growth of the AAA. The aim of our study was to assess the asymmetrical thrombus deposition index in ruptured and symptomatic aneurysms. We collected data for 33 aneurysms, 21 (63.63%) asymptomatic and 12 (33.37%) ruptured or symptomatic. Asymmetrical thrombus deposition index (ATDI) was measured by Onis DICOM viewer software. Also, lumen's geometrical centre (LGC) was defined and ATDI was considered positive when the LGC was laid on the posterior section of the sac (meaning dominant anterior ILT distribution) and negative when it was laid on the anterior section (meaning dominant posterior ILT distribution). Maximum aneurysm diameter was 63.4mm in average (50-100mm, SD=12.89); 59.8mm in asymptomatic and 71.16mm in symptomatic or ruptured aneurysm (p=0.012). The absolute value of asymmetric thrombus deposition index was significantly higher in symptomatic/ruptured compared to asymptomatic aneurysm, 0.54 and 0.33, respectively (p=0.041), while there was no difference in frequency of positive or negative thrombus deposition (p=0.261). There was no significant correlation between maximal aneurysm size and absolute value of ATDI (p=0.505). Values of thrombus deposition index are correlating with the development of symptomatology or rupture of the AAA. This variable should be included in much wider mathematical rupture prediction model in order to have more accurate rupture risk assessment. © 2015 IEEE.

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Congenital vascular malformations (CVMs) are not rare disorders, with the overall incidence of 1.5%. Due to their complex embryology and various clinical presentations, there was a long lasting confusion among vascular specialists regarding the etiology, classification, basic principles of evaluation and treatment of these anomalies. The introduction of the Hamburg classification and its adoption by experts around the world made further studies of CVMs and comparison of results among different specialists possible. Precise diagnosis of the type and extent of the malformation is paramount for the choice of adequate treatment. In most instances this can be achieved with a detailed history, careful physical examination and a combination of appropriate non-invasive studies. Invasive tests should be reserved for confirmation of diagnosis and serve as a road map for treatment planning. Modern treatment of CVMs is based on a multidisciplinary team approach involving specialists in vascular surgery, interventional radiology, pediatrics, nuclear medicine, orthopedic surgery, plastic and reconstructive surgery and physical therapy. Surgical and endovascular techniques are used in conjunction to minimize morbidity and improve treatment outcomes.