SummaryThe distribution of atherosclerotic plaque burden in the human coronary arteries is not uniform. Plaques are located mostly in the left anterior descending artery (LAD), then in the right coronary artery (RCA), circumflex branch (LCx) and the left main coronary artery (LM) in a decreasing order of frequency. In the LAD and LCx, plaques tend to cluster within the proximal segment, while in the RCA their distribution is more uniform. Several factors have been involved in this phenomenon, particularly flow patterns in the left and right coronary artery. Nevertheless, it does not explain the difference in lesion frequency between the LAD and the LCx as these are both parts of the left coronary artery. Branching points are considered to be the risk points of atherosclerosis. In the LCx, the number of side branches is lower than in the LAD or RCA and there are no septal perforators with intramuscular courses like in the proximal third of the LAD and the posterior descending artery (PDA). We hypothesized that septal branches generate disturbed flow in the LAD and PDA in a similar fashion to the myocardial bridge (myocardial bridging effect). This coronary architecture determines the non-uniform plaque distribution in coronary arteries and LAD predisposition to plaque formation.

This review discusses visual and functional evaluation of the hemodynamic significance of the degree of stenosis in coronary angiography, with respect to the indications for revascularization. The concept of the coronary flow reserve is defined, and the theoretical assumptions of the invasive measurement of the fractional flow reserve (FFR) are presented. In the following part, the publication describes the basic steps of numerical stimulations in terms of computational fluid dynamics (CFD) in calculating the fractional flow reserve based on computed tomography (CT) coronary angiography (FFRCT). The numerical FFRCT estimation in correlation with invasive measurements, as well as benefits deriving from FFRCT in the diagnosis of coronary artery disease, is presented in the example of the multicentre prospective DISCOVER-FLOW trial and the DeFACTO project. The CDF method enables to obtain hemodynamic significance of stenosis solely from the coronary anatomy vizualized by CT angiography. The calculation of FFRCT increases the diagnostic reliability of coronary flow reserve estimations. It contributes to the improvement in patients’ qualification for contrast coronarography. If the accuracy of FFRCT is confirmed in clinical practice, and the time required for computational processing is shortened, it may turn out that the algorithms of coronary heart disease diagnosis will be verified and it will be to a greater extent based on the CT results.

IntroductionTranscatheter aortic valve implantation (TAVI) improves prognosis in patients disqualified from surgical valve replacement. Calcifications of the aortic complex can lead to deformation of the prosthesis, resulting in paravalvular leaks (PVL).AimTo evaluate the predictive value of quantitative estimation of volume/weight and geometric distribution of calcifications in multislice computed tomography, for the development of PVL.Material and methodsThis was a retrospective, case-control study on patients with a CoreValve aortic prosthesis. The study group consisted of 20 patients with confirmed significant PVL after TAVI. The control group consisted of 20 patients without significant PVL, matched according to valve type and clinical characteristics. The size spatial distribution and shape of calcifications were measured.ResultsThe average age of patients was 79.9 years (60% women). Cases and controls did not differ in their clinical characteristics. The size of the aortic annulus was significantly larger in cases vs. controls (23.4 ±1.6 vs. 22 ±1.4 mm, p = 0.01). Volume, area and curvature of calcifications were greater in cases vs controls (1.09 ±0.56 vs. 0.59 ±0.41 cm3, p = 0.011; 15.26 ±5.46 vs. 9.50 ±5.29 cm2, p = 0.008; 1.76 ±0.07 vs. 1.68 ±0.13 cm3, p = 0.037). In multivariate analysis, adjusted for aortic annulus size, the area of aortic valve calcifications independently predicted paravalvular regurgitation (OR = 1.41, 95% CI: 0.09–1.92, p < 0.009).ConclusionsMorphometric analysis of aortic valve calcifications predicted the risk of paravalvular leak following TAVI irrespectively of patients’ clinical characteristics.

SummaryAortic valve calcification (AVC) is a common disease of the elderly. It is a progressive disease ranging from mild valve thickening to severe calcification with aortic valve stenosis. Risk factors for AVC are similar to those for atherosclerosis: age, gender, hypercholesterolemia, diabetes, hypertension, smoking and renal failure. AVC shares many similarities to atherosclerosis, including inflammatory cells and calcium deposits, and correlates with coronary plaque burden. Presence of AVC is associated with increased risk of adverse cardiovascular events. The objective for this review is to discuss the clinical features, natural history and prognostic significance of aortic valve calcifications, including mechanical and hemodynamic factors of flow distribution.

Hydrodynamic cavitation caused by the Venturi effect is one of the most promising methods of sewage sludge pre-treatment. This study has been carried out to investigate the effect of hydrodynamic cavitation on disintegration of activated sludge foam and mesophilic fermentation. Cavitation was generated in standard Venturi tube with the diameter ratio β = d0/d1 = 0.30, working at σ = 0.249. Detailed Computational Fluid Design (CFD) analysis in class of k-∈ model of internal flow has been presented. Obtained analytical investigation results confirmed the effect of strong disruption of microorganism cells and release of free organic substance into the liquid phase. After a short (30 minutes) pre-treatment, chemical oxygen demand increased by 8.63 times while Müller's disintegration degree was 50%. Moreover, undertaken mesophilic digestion trials brought significant improvement in biogas production.