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In this study, we investigate plaques located at the left coronary bifurcation. We focus on the effect that the resulting changes in wall shear stress (WSS) and wall pressure stress gradient (WPSG) have on atherosclerotic progress in coronary artery disease. Coronary plaques were simulated and placed at the left main stem and the left anterior descending to produce >50% narrowing of the coronary lumen. Computational fluid dynamics analysis was carried out, simulating realistic physiological conditions that show the in vivo cardiac haemodynamic. WSS and WPSG in the left coronary artery were calculated and compared in the left coronary models, with and without the presence of plaques during cardiac cycles. Our results showed that WSS decreased while WPSG was increased in coronary side branches due to the presence of plaques. There is a direct correlation between coronary plaques and subsequent WSS and WPSG variations based on the bifurcation plaques simulated in the realistic coronary models.

This study investigates the hemodynamic changes to various types of coronary stenosis in the left coronary artery bifurcation, based on a patient-specific analysis. Twenty two patients with left coronary artery disease were included in this study. All stenoses involving the left coronary artery bifurcation were classified into four types, according to their locations: A) left circumflex (LCx) and left anterior descending (LAD), B) LCx only, C) left main stem only, and D) LAD only. Computational fluid dynamics (CFD) was performed to analyze the flow and wall shear stress (WSS) changes in all reconstructed left coronary geometries. Our results showed that the flow velocity and WSS were significantly increased at stenotic locations. High WSS was found at >70% lumen stenosis, which ranged from 2.5 Pa to 3.5 Pa. This study demonstrates that in patients with more than 50% stenosis in the left coronary artery bifurcation, WSS plays an important role in providing information about the extent of coronary atherosclerosis in the left coronary artery branch., (Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.)

Purpose: Coronary plaque has been shown to directly affect the blood parameters, however, haemodynamic variations based on the plaque configuration has not been studied. In this study we investigate the haemodynamic effects of various types of plaques in the left coronary bifurcation., Methods: Eight types of plaque configurations were simulated and located in various positions in the left main stem, the left anterior descending and left circumflex to produce a >50% narrowing of the coronary lumen. We analyse and characterise haemodynamic effects caused by each type of plaque. Computational fluid dynamics was performed to simulate realistic physiological conditions that reveal the in vivo cardiac haemodynamics. Velocity, wall shear stress (WSS) and pressure gradient (PSG) in the left coronary artery were calculated and compared in all plaque configurations during cardiac cycles., Results: Our results showed that the highest velocity and PSG were found in the type of plaque configuration which involved all of the three left coronary branches. Plaques located in the left circumflex branch resulted in highly significant changes of the velocity, WSS and PSG (p<0.001) when compared to the other types of plaque configurations., Conclusion: Our analysis provides an insight into the distribution of plaque at the left bifurcation, and corresponding haemodynamic effects, thus, improving our understanding of atherosclerosis., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

This study analyses the hemodynamic variations surrounding stenoses located at the left coronary bifurcation, and their influence on the wall shear stress (WSS) in realistic coronary geometries. Four patients with suspected coronary artery disease were chosen, and coronary models were reconstructed based on high-resolution CT data. The coronary stenoses were observed at the left circumflex and left anterior descending branches, resulting in a lumen narrowing of >50%. Flow analysis was performed using computational fluid dynamics, to simulate the cardiac flow conditions of the realistic individual patient geometry. Blood flow and WSS changes in the left coronary artery were calculated throughout the entire cardiac phases. Our results revealed that the recirculation regions were found at the poststenotic locations. WSS was found to increase at the stenotic positions in all four patients. There is a strong correlation between coronary stenosis and the hemodynamic changes, which are reflected in blood flow pattern and WSS, based on the realistic left coronary geometries.

The aim of this study was to investigate the plaques at the left coronary artery (LCA) and their effect on the haemodynamic and wall shear stress (WSS) in realistic patient models. Three sample patients with left coronary disease were selected based on CT data. The plaques were present at the left anterior descending and left circumflex branches with more than 50 % lumen narrowing. Computational fluid dynamics analysis was used to perform simulation of patient-specific models with realistic physiological conditions that demonstrate in vivo cardiac flow. WSS and blood flow in the LCA were measured during cardiac cycles. Our results showed that WSS was found to increase at the stenotic locations and decrease at pre- and post-plaque locations, whilst the recirculation location was found at post-plaque regions. There is a strong correlation between coronary bifurcation plaques and hemodynamic and WSS changes, based on the realistic coronary disease models.

This study was to investigate the hemodynamic effect of simulated plaques in left coronary artery models, which were generated from a sample patient's data. Plaques were simulated and placed at the left main stem and the left anterior descending (LAD) to produce at least 60% coronary stenosis. Computational fluid dynamics analysis was performed to simulate realistic physiological conditions that reflect the in vivo cardiac hemodynamics, and comparison of wall shear stress (WSS) between Newtonian and non-Newtonian fluid models was performed. The pressure gradient (PSG) and flow velocities in the left coronary artery were measured and compared in the left coronary models with and without presence of plaques during cardiac cycle. Our results showed that the highest PSG was observed in stenotic regions caused by the plaques. Low flow velocity areas were found at postplaque locations in the left circumflex, LAD, and bifurcation. WSS at the stenotic locations was similar between the non-Newtonian and Newtonian models although some more details were observed with non-Newtonian model. There is a direct correlation between coronary plaques and subsequent hemodynamic changes, based on the simulation of plaques in the realistic coronary models.

The purpose of this study was to investigate the hemodynamic effect of variations in the angulations of the left coronary artery, based on simulated and realistic coronary artery models. Twelve models consisting of four realistic and eight simulated coronary artery geometries were generated with the inclusion of left main stem, left anterior descending and left circumflex branches. The simulated models included various coronary artery angulations, namely, 15°, 30°, 45°, 60°, 75°, 90°, 105° and 120°. The realistic coronary angulations were based on selected patient's data with angles ranging from narrow angles of 58° and 73° to wide angles of 110° and 120°. Computational fluid dynamics analysis was performed to simulate realistic physiological conditions that reflect the in vivo cardiac hemodynamics. The wall shear stress, wall shear stress gradient, velocity flow patterns and wall pressure were measured in simulated and realistic models during the cardiac cycle. Our results showed that a disturbed flow pattern was observed in models with wider angulations, and wall pressure was found to reduce when the flow changed from the left main stem to the bifurcated regions, based on simulated and realistic models. A low wall shear stress gradient was demonstrated at left bifurcations with wide angles. There is a direct correlation between coronary angulations and subsequent hemodynamic changes, based on realistic and simulated models. Further studies based on patients with different severities of coronary artery disease are required to verify our results., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Sixty-three patients with inoperable symptomatic non-small cell carcinoma of the bronchus were randomly allocated to receive either vincristine (1.4 mg/m2) or vindesine (3 mg/m2). These drugs were given weekly for four doses, then every 2 weeks for two further doses, and then continued monthly if there had been a response. Only five partial responses (greater than 50% reduction) were obtained with vindesine and none with vincristine. Disabling toxic effects occurred in 13 patients. This was more common with vindesine, but this group also received more prolonged therapy. Vindesine has modest activity against non-small cell carcinoma of the bronchus and may be more effective than vincristine, with similar toxicity.