ABSTRACT
Objective To conduct a comprehensive study on pulsatile blood flow in arteries by proposing a convenient theoretical research system for hemodynamics. Methods Based on Womersley algorithm for fully developed pulsatile flow, numerical algorithm was introduced to establish the solving and analytical system of hemodynamics based on flow rate in arteries during one cardiac cycle. The flow rate of carotid artery in pig was measured under three blood flow states: the ideal state with a sinusoidal inflow waveform, the normal physiological state and the enhanced external counterpulsation (EECP) state for comprehensive hemodynamic research. Results Important hemodynamic parameters such as the axial speed vector, the wall shear stress (WSS), and the oscillatory shear index (OSI) during one cardiac cycle under the mentioned three flow states were solved respectively. The waveform of flow rate had a certain effect on WSS distributions and OSI level; the EECP performance obviously resulted in a significant increase in the level of WSS (WSS peak in particular) and OSI. Conclusions The solving system developed in this paper can be used for hemodynamics study conveniently and effectively. One of the most important hemodynamic mechanisms that lead to EECP’s good clinical effect may lie in its promotion to WSS level under physiological state, but the effect of OSI on endothelial function of the artery might much smaller than WSS itself; therefore, OSI may not be an ideal hemodynamic index for predicting the lesion of atherosclerosis.
ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of chronic enhanced external counterpulastion (EECP) on gene expression profiles of arterial endothelial cells (ECs) of pigs fed with high-cholesterol diet.</p><p><b>METHODS</b>Eight male pigs were fed with high-cholesterol diet for 12 weeks to induce arteriosclerosis and subjected to EECP for accumulative 36 h (2 h every other day for 18 sessions). Another 8 pigs on cholesterol-enriched diet and 6 normally fed pigs served as the arteriosclerosis model group and normal control group, respectively, and the high-cholesterol diet was maintained until the end of EECP treatment. The coronary artery was then isolated for transmission electro microscopy, and the abdominal aorta was observed using Sudan III staining. The gene expression profiles in ECs from the thoracic aorta using cDNA microarrays.</p><p><b>RESULTS</b>Macrophages and foam cells were detected beneath the ECs in the coronary artery of pigs in the model group, but not in the other two groups. The ratios of Sudan III-positive area in the celiac aorta were significantly lower in normal control and EECP groups than in the model control group (P<0.05). Compared with the normal control group, the gene expressions of integrins-beta1 and CTGF were up-regulated in the model group. Compared with the model group, the expressions of integrins-beta1, CTGF and VCAM-1 were down-regulated and eNOS up-regulated in EECP group.</p><p><b>CONCLUSION</b>Chronic EECP may reduce endothelial injury, down-regulate the gene expression level of integrin-beta1, CTGF and VCAM-1, lower cholesterol uptake and attenuate arterial endothelial inflammation to protect the pigs fed with high-cholesterol diet from arteriosclerosis.</p>