Jiří Moláček

Optimization of the Model of Abdominal Aortic Aneurysm – Experiment in an Animal Model

Background: Many studies have been performed in order to model abdominal aortic aneurysm (AAA) in an experimental animal, most commonly in small laboratory animals. In our study, we tried to find the best AAA model in a pig by using various mechanical and enzymatic mechanisms. Methods: Twenty-two pigs were operated on. We combined 3 mechanisms of creating an AAA, using an intraluminal infusion of porcine pancreatic elastase into the abdominal aortic segment, application of plastic cuff below the renal arteries causing turbulent blood flow, and inserting a patch into the longitudinal aortotomy. Results: We found different results in different groups according to the mechanisms used. In group A, with a combination of the intraluminal elastase infusion and application of a stenosing cuff, AAA developed in all 7 animals (100%). In this group, we also found the largest histological changes in the abdominal aorta samples. Conclusion: The use of intraluminal pancreatic elastase infusion, together with increased turbulent flow caused by the stenosing cuff, seems to be the best model of AAA in pigs. This model is suitable for further research in the etiopathology of AAA. In fact, it is the first successful approach to a large-caliber native aneurysm model.Background: Many studies have been performed in order to model abdominal aortic aneurysm (AAA) in an experimental animal, most commonly in small laboratory animals. In our study, we

Asymptomatic Abdominal Aortic Aneurysms Show Histological Signs of Progression: A Quantitative Histochemical Analysis

Objective: Abdominal aortic aneurysm (AAA) is a serious disease due to its covert nature, relatively high prevalence and fatal prognosis in the case of rupture. To obtain new insights into AAA pathogenesis, we examined the relationships between histopathology, multiplex in vitro immunoassay data, diameter and symptomatology. Methods: In a prospective, non-randomised study, we evaluated samples from 6 normal infrarenal aortae and 65 AAA patients (65 walls, 55 thrombi). The AAA patients were either asymptomatic (n = 44), symptomatic (n = 7) or with ruptured AAA (n = 14). The AAA diameter was classified as small (<5 cm, n = 18), medium (5–7 cm, n = 26) and large (>7 cm, n = 21). We quantified the histopathology of the AAA wall and the adjacent thrombus. We assessed the expression of proteins in the same samples. Results: Asymptomatic AAAs had walls with more abundant inflammatory infiltrates, lower amounts of PAI-1, a higher number of tPA-positive elements, a tendency towards decreased collagen content, whereas the adjacent thrombi had a greater concentration of VCAM-1 and MMP-2 when compared with symptomatic AAAs. Compared with the aneurysmatic aorta, the normal aorta contained less collagen and more elastin, actin, desmin and PAI-1-positive elements; in addition, it was more vascular. Medium-sized AAAs were the most actin and vimentin rich, and large AAAs were the most vascular. Conclusion: Our results show that asymptomatic AAA walls often have more potentially deleterious histopathological alterations than symptomatic AAA walls. This result indicates that a progression from an asymptomatic AAA to rupture can be expected and screening patients who are at risk of rupture could be beneficial.

Low contrast volume run-off CT angiography with optimized scan time based on double-level test bolus technique – feasibility study

PURPOSE To verify the technical feasibility of low contrast volume (40 mL) run-off CT angiography (run-off CTA) with the individual scan time optimization based on double-level test bolus technique. MATERIALS AND METHODS A prospective study of 92 consecutive patients who underwent run-off CTA performed with 40 mL of contrast medium (injection rate of 6 mL/s) and optimized scan times on a second generation of dual-source CT. Individual optimized scan times were calculated from aortopopliteal transit times obtained on the basis of double-level test bolus technique--the single injection of 10 mL test bolus and dynamic acquisitions in two levels (abdominal aorta and popliteal arteries). Intraluminal attenuation (HU) was measured in 6 levels (aorta, iliac, femoral and popliteal arteries, middle and distal lower-legs) and subjective quality (3-point score) was assessed. Relations of image quality, test bolus parameters and arterial circulation involvement were analyzed. RESULTS High mean attenuation (HU) values (468; 437; 442; 440; 342; 274) and quality score in all monitored levels was achieved. In 91 patients (0.99) the sufficient diagnostic quality (score 1-2) in aorta, iliac and femoral arteries was determined. A total of 6 patients (0.07) were not evaluable in distal lower-legs. Only the weak indirect correlation of image quality and test-bolus parameters was proved in iliac, femoral and popliteal levels (r values: -0.263, -0.298 and -0.254). The statistically significant difference of the test-bolus parameters and image quality was proved in patients with occlusive and aneurysmal disease. CONCLUSION We proved the technical feasibility and sufficient quality of run-off CTA with low volume of contrast medium and optimized scan time according to aortopopliteal transit time calculated from double-level test bolus.

Regadenoson-Stress Dynamic Myocardial Perfusion Improves Diagnostic Performance of CT Angiography in Assessment of Intermediate Coronary Artery Stenosis in Asymptomatic Patients.

The prospective study included 54 asymptomatic high-risk patients who underwent coronary CT angiography (CTA) and regadenoson-induced stress CT perfusion (rsCTP). Diagnostic accuracy of significant stenosis (≥50%) determination was evaluated for CTA alone and CTA + rsCTP in 27 patients referred to ICA due to the positive rsCTP findings. Combined evaluation of CTA + rsCTP had higher diagnostic accuracy over CTA alone (per-segment: specificity 96 versus 68%, p = 0.002; per-vessel: specificity 95 versus 75%, p = 0.012) and high overruling rate of rsCTP was proved in intermediate stenosis (40–70%). Results demonstrate a significant additional value of rsCTP in the assessment of intermediate coronary artery stenosis found with CTA.

Tissue levels of interleukins 6, 8 and of tumor necrosis factor alpha in the wall of ruptured and asymptomatic abdominal aortic aneurysms

ZusammenfassungGRUNDLAGEN: Entzündliche Veränderungen der atherosklerotischen Plaques spielen eine wichtige Rolle in der Ätiologie des abdominellen Aortenaneurysmas (AAA), wobei dafür proinflammatorische Zytokine bedeutsam sind. Das Ziel unserer Studie war, die Wichtigkeit der Entzündung für die Entstehung der Aneurysmen zu untersuchen. METHODIK: Cytosolspiegel der Interleukine 6 und 8 (IL 6, IL 8), Tumor-Nekrose-Faktor-α (TNF-α) in der Wand des Aortenaneurysm wurden in einer prospektiv-nicht- randomisierten Studie mit 110 Patienten beurteilt. Gruppe I (Aneurysmenruptur, N = 41), Gruppe II (asymptomatische Aneurysmen, N = 54), Gruppe III (Kontrollgruppe: 15 Nierenspendern). Zur Feststellung der entzündlichen Zellen in der Aorta-Wand dienten die immunohistochemische Untersuchung, sowie Licht- und Elektronenmikroskopie. ERGEBNISSE: In Aneurysmenrupturen fanden sich entzündliche Veränderungen, und wir haben in der Wand erhöhte IL 6 (P < 0,001), IL 8 (P < 0,0003) und TNF-α- Spiegel (P < 0,002) gefunden. Die meisten Zellen in den entzündlichen Infiltraten waren Stammzellen-B (CD 45 und CD 20 Antigen). SCHLUSSFOLGERUNGEN: Die Entzündung spielt eine wichtige Rolle in der Pathogenese des abdominellen Aortenaneurysmas, vorzugsweise bei rupturierten Aneurysmen. Diese Erkenntnisse müssen durch größere klinische Studien bestätigt werden. Möglicherweise können Medikamente, die gegen Zytokine wirksam sind, eine Hemmung der Entzündung im Aneurysma bewirken.SummaryBACKGROUND: Inflammation of abdominal aortic aneurysm (AAA) wall plays an important role in the etiopathogenesis of AAA. Proinflammatory cytokines are probably the key factors in this process. The aim of this study was to evaluate the significance of inflammation for AAA rupture. METHODS: Cytosol levels of interleukin 6, 8 (IL 6, 8), tumor necrosis factor-α (TNF-α) in the AAA walls were evaluated in a prospective non-randomised study including 110 patients: Group I (ruptured aneurysms, N = 41), group II (asymptomatic aneurysms, N = 54), group III (control group) consisted of 15 kidney donors. Aortic walls were examined using immunohistochemistry, light and electron microscopy to detect inflammatory cells. RESULTS: The significant inflammatory changes were found in the walls of the ruptured aneurysms with increased levels of IL 6 (P < 0.001), IL 8 (P < 0.0003) and TNF-α (P < 0.002). The majority of cells within the inflammatory infiltrates was of B-cell origin (CD 45 and CD 20 antigen). CONCLUSIONS: Inflammation plays an important role in the pathogenesis of abdominal aortic aneurysm especially in ruptured aneurysms. Additional clinical studies are needed to support this observation and test if anti-cytokine-drugs may play a role in the prevention of aneurysm rupture.